U.S. patent application number 10/774728 was filed with the patent office on 2005-08-11 for transonic hull and hydrofield (part iii-a).
Invention is credited to Alvarez-Calderon F., Alberto.
Application Number | 20050172881 10/774728 |
Document ID | / |
Family ID | 34827036 |
Filed Date | 2005-08-11 |
United States Patent
Application |
20050172881 |
Kind Code |
A1 |
Alvarez-Calderon F.,
Alberto |
August 11, 2005 |
Transonic hull and hydrofield (part III-A)
Abstract
A transonic hull having a bow, a stern, a longitudinal length
therebetween, side surfaces extending from the bow to outboard
portions of the stern, a lower surface extending between the side
surfaces, the transonic hull having a submerged volume with an
approximately triangular shape in planview with apex adjacent the
bow and a base adjacent the stern, and an approximately triangular
shape in side view when in motion with a base adjacent the bow and
an apex adjacent the stern.
Inventors: |
Alvarez-Calderon F., Alberto;
(La Jolla, CA) |
Correspondence
Address: |
LAW OFFICES OF ADAM H. JACOBS
PATENT ATTORNEY
SUITE 726
1904 FARNAM STREET
OMAHA
NE
68102
US
|
Family ID: |
34827036 |
Appl. No.: |
10/774728 |
Filed: |
February 9, 2004 |
Current U.S.
Class: |
114/283 |
Current CPC
Class: |
Y02T 70/125 20130101;
B63B 1/20 20130101; B63B 1/14 20130101; Y02T 70/10 20130101; B63B
1/40 20130101 |
Class at
Publication: |
114/283 |
International
Class: |
B63B 001/20 |
Claims
I claim:
1. A multihull craft comprising a principal hull of displacement
type and a lateral hull of semi-planning type.
2. The craft of claim 1 in which said lateral hull is of the semi
displacement type.
3. The craft of claim 1 in which said lateral hull is of the
transonic hull type.
4. The craft of claim 1 in which all hulls are of the transonic
hull type.
5. The craft of claim 1 in which lateral wing support extends
between said lateral hull and said principal hull.
6. A multihull configuration comprising a principal hull, a lateral
hull, and a supporting structure therebetween, with hydrodynamic
impellers mounted on said supporting structure to capture the
rearward flow between said principal and lateral hulls and impel
said rearward flow in a rearward direction at a higher speed.
7. A man powered craft having a principal body and a lateral
elongated body articulated on a side of said principal body, said
elongated body adapted to be moved between an upper level
disposition, and a lower level disposition in which the volume of
said lateral body can generate a lateral change of buoyant forces
when said principal body is heeled.
8. A slender man-powered craft having an aerodynamic impeller
driven by an electric motor powered by batteries for selective use
by said man.
9. The craft of claim 8 having solar cells to recharge said
batteries.
10. The craft of claim 9 in which said craft has a wing of large
chord and large area supporting a lateral hull with said area
providing substantial additional area for increased number of solar
cells.
11. A multihull having a principal displacement type hull and a
lateral hull of transonic hull shape, with the speed/length ratios
of outer hull being larger than that of principal hull by a factor
greater than approximately 1.5.
12. The multihull of claim 11 in which said multihull is of a
man-powered type.
13. A multihull having a principal hull and a lateral hull
connected to said principal hull by an approximately horizontal
structure when operating in the water, said structure being
articulated at its root at an approximately longitudinal
articulation which permits change of inclination of said structure
in front view.
14. A multihull having a principal hull, and a lateral hull with
each of said hulls having similar triangular waterplane planform
shapes with narrow end forward and broad end rearwards, and with
each said multihulls having, at any given speed, a speed/length
ratio of said outer hull no less than approximately 1.5 times that
of the principal hull.
15. A vessel having a body with a bow, a stern, a longitudinal
length, and a waterplane in hydrostatic condition, said water plane
having a substantially triangular shape with a pointed end adjacent
said bow and a broad end adjacent said stern, said vessel further
characterized in that the waterplane of said broad end has outboard
ends and a center region, with said center region being upstream of
said outboard ends, forming in planform a shallow Vee therebetween.
Description
SUMMARY OF THE INVENTION
[0001] The present invention specifies new unique design shapes,
features, and methods of operation which qualitatively improve and
extend the scope of the transonic hull TH and the transonic
hydrofield TH inventions of patent application Ser. Nos. 08/814,418
and 08/814,017. The scope of the present invention is summarized
below:
[0002] 1. An extension of the operational speed envelope of TH over
a very broad speed range increase by means of new design
characteristics and new hydrodynamic regimes beyond the previous
subcritical and supercritical regimes in the displacement modes,
namely: the hypercritical, the transplanar, and the x-regimes. With
these improvements, a single TH hull can operate with good
efficiency over a large speed spectrum which otherwise would
require two or three ships with different conventional hulls; for
example, a conventional displacement ship at lower range of speed
and a vee-bottom or semi-planing hull for higher speeds.
[0003] 2. Another important feature of the invention pertains to
hull characteristics and shapes above and below calm-water
waterplane which are critical to permit successful operation over
the broad speed regime in adverse seas, preferably also in optional
combination with special longitudinal distribution of heavy mass
components inside the hull, such as engines, fuel, and weapons.
[0004] 3. A third feature of the invention pertains to special
shapes, trim, balance, center of gravity location, location of
longitudinal center of flotation, and various kinds of flaps and
streaks needed to make feasible and enhance and improve the
performance and maneuverability of the transonic hull in calm water
and adverse seas.
[0005] 4. Additionally, other important features of the invention
are its hull shapes which have inherent low detectability by radar
and other sensors, as well as a wake of low visibility and thermal
content, which yields stealth properties to the hull which are
nevertheless compatible with efficient hydrodynamics and good
behavior in adverse seas.
[0006] Thus, the new invention is an all weather stealth transonic
hull capable of operating in new high speed hydrofield regimes of
the transonic hull, which now includes the hypercritical,
transplanar, and X regimes. For simplicity, the hull of the present
invention is also referred to in certain important cases as TH-II,
and its broadened hydrofield is TH-II. Other embodiments of the
present invention are improvements applicable to TH and TH-II.
[0007] Because the invention is broad and powerful, it is not
necessary to incorporate in a single vessel each and all features
and methods of the inventions and improvements, nor is it necessary
to incorporate each of them in all claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIGS. 1, 2, 3 and 4 are examples of the prior art related to
this invention; are views of the cover planform and profile view of
TH, and planview of TH of the present invention;
[0009] FIGS. 5, 7a, 7b, 9, 10, 11, 12a, 12b and 14f cover examples
shown in previously filed application Ser. No. 08/814,418; and
[0010] FIG. 8 specifies the relation between drag and V/{square
root}L for TH and IACC hulls;
[0011] FIGS. 13a and 13b disclose the TH-II and TH-II in
hypercritical regime;
[0012] FIGS. 14a and 14b disclose the TH-II and TH-II in
transplanar regime;
[0013] FIGS. 14c and 14d disclose the stern profile and flap;
[0014] FIG. 14e discloses the combination of the stern flap and
profile thereof;
[0015] FIG. 15 discloses the TH-II and TH-II in X-regime;
[0016] FIG. 16 discloses the stern and side flap for control;
[0017] FIG. 17 discloses the TH and TH in sea waves with lateral
flaps for control;
[0018] FIGS. 18a-g disclose the TH 3-D shape for operation in
adverse seas and stealth operation;
[0019] FIGS. 19-28c disclose further embodiments and structures
associated with the TH and TH of the present invention; and
[0020] FIGS. 29-49 disclose further additional embodiments and
structures associated with the TH and TH of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] The nature and scope of the present invention can be better
understood by reviewing the principal characteristics of
conventional hulls, which have certain serious inherent problems in
calm water and in an adverse sea, and examining also the limits and
potential of transonic hulls TH and their hydrofields in patent
application Ser. Nos. 08/814.418 and 08/814.417, all which sets the
conceptual inquiry solved by the present invention.
[0022] 1. Characteristics and Problems of Conventional Hulls.
[0023] It is necessary for this review to separate the conventional
hull designs by hull types in accordance to their operational speed
envelopes. The envelopes are expressed for each hull type in terms
of weight-to-drag ratios as function of speed-to-length ratios,
best considered together with their corresponding volumetric
coefficients, which are indicative of longitudinal surface and
volume distributions responsive to their speed envelopes.
[0024] 1a. Displacement Hulls.
[0025] Displacement hulls sustain boat weight by buoyant lift. As
designed in the past and present, they have an upper speed limit
called "hull speed," near and above which hydrodynamic resistance
(drag) grows at a high exponential rate, for example, as in FIG. 1.
The "hull speed" occurs when the length between bow and stern waves
generated by and traveling with the translating hull equals the
geometric length of the hull. This situation is expressed
numerically when the ratio of boat speed in knots divided by square
root of boat length in feet equals 1.34.
[0026] Displacement hulls are very efficient well below hull speeds
with weight-to-drag ratio of over 100. At extremely low speeds, the
efficiency ratio increases to much higher values, because drag
approaches zero but weight remains constant. However, near or above
hull speed, their weight-to-drag ratio decreases rapidly and
becomes physically and economically unacceptable. Therefore, higher
speeds of displacement hulls is attainable principally by
increasing hull length. Unfortunately, the speed advantage of
length is not large. For example, the nominal "hull speed" of a 50
foot hull is 9.5 knots, but for 300 foot hull speed, it is only 23
knots.
[0027] The "hull speed" limit is intrinsic of displacement hulls,
because of their wave generation properties as they translate in
the water, i.e., "wave making." When the length of waves generated
by the hull exceed the geometric length of the hull, as shown in
FIG. 2, the situation becomes critical. The increasing size of bow
wave with increasing speed induces a further drop of the trough
near midbody, leading to incremental sinkage of the hull and an
increase of hull's angle of attack. There is also the additional
sinkage with speed increase due to the curvature of the hull below
local water levels. The increase of angle of attack impedes further
speed increase unless very large power is available to climb over
the bow wave and enter the planing regime, the limitations of which
will be discussed later on.
[0028] The high drag due to wave-making adds to and can exceed
friction drag, and is a very serious problem in the economics of
maritime transportation. Accordingly, considerable research has
been done in various ways to overcome it, unfortunately with only
minor improvements. For example, a bulbous bow may slightly
decrease drag at certain speeds. Also, long slender hulls are less
sensitive than beamy hulls, but carry less cargo, and have other
problems, as will be reviewed later on.
[0029] The principal characteristics of displacement hulls which
cause and determine their maximum operational speed envelopes are
available in various sources (for example, "A Comparative
Evaluation of Novel Ship Types," by MIT's Professor Philip Mandel)
and is summarized on the left side of FIGS. 3 and 4. The
operational speed envelope covers speed-to-length ratios of 0.8 to
about 1.0 or 1.1 for commercial ships, which is well below their
"hull speeds" of 1.34. Military ships have speed envelopes that
include "hull speed" (for example, a cruiser ship at 1.35) and even
above "hull speed" (for example, the slender destroyer operating at
speed-to-length ratio of about 1.7). Above the speed ratios
described, the required size and weight of conventional power
plants and hydrodynamic problems of propulsion at the lower
weight-to-drag ratios become unacceptable for the missions of the
ships.
[0030] Accordingly, there remains an urgent need for improving the
high speed efficiency and range of displacement hulls, at least
within their current speed limits and preferably in a breakout
above those limits. A practical solution is needed, especially if
it is able to eliminate wave-making drag of the type which limits
conventional hulls, without recourse to conventional hydrodynamic
planing.
[0031] 1b. Planing Hull.
[0032] There is a widely held view that a different type of hull,
called planing hull, in which weight is supported by a hydrodynamic
lift force from momentum change (as distinct from buoyant lift),
can overcome the speed limits of displacement hulls, and
furthermore that they are efficient at high speed. Actually, while
planing permits high boat speed, it does so only for boats with an
approximately flat underbody having relatively light weight and
equipped with large propulsive thrust. The limiting characteristics
of this hull is the presence of dynamic drag due to momentum
change, shown in FIG. 5 for the limiting case of inviscid planing.
In practice, these hulls operate at angles of attack of 3.degree.
to 6.degree.. The inviscid weight-to-drag ratio for optimum flat
plate planing case is 19 and 9.5 respectively.
[0033] When viscous drag is added to dynamic drag, the fact is that
planing is a grossly inefficient hydrodynamic regime, since the
best ratio of boat weight to resistance is in the order of 6 to 9,
as shown on the right sides of FIGS. 3 and 4. This is less than
half that of a modern jet transport flying about 10 times faster,
and only {fraction (1/10)}.sup.th (or less) that of a displacement
hull of "reasonable" length near, but below, hull speed. The
operational speed envelope of planing hulls are best exemplified by
the ski boats and similar sports craft which below their planing
speeds (for example, below a speed-to-length ratio of about 4)
require a nose-high attitude with large wave-making drag in
displacement mode, a condition similar to that shown for the lowest
but longer hull in FIG. 2.
[0034] Although the decrease of weight-to-drag ratio with speed in
FIG. 3 appears to be continuous with increasing speed-to-length
ratio, the left and right sides in FIG. 3 are not continuous, but
discontinuous as to shape and type of hulls--displacement and
planing--which have discontinuous and widely different volumetric
coefficients, as is clearly shown in FIG. 4. Thus, on the left in
FIGS. 3 and 4, displacement hulls, if one includes destroyers,
cover an operational speed-to-length envelope from about 0.8 to
1.8, in which the weight-to-drag ratio decreases smoothly from over
120 (higher for slow tankers) to about 25, which the corresponding
volumetric coefficient decreasing smoothly from about 80 (higher
for slow tankers) to about 55 for destroyers. In contrast, on the
right sides in FIGS. 3 and 4, planing hulls have an operational
speed-to-length ratio of the order of 3 to well above 4 (FIG. 3),
but with weight-to-drag ratios of about 6-8, and with a volumetric
coefficient of above 100 (FIG. 4), which is evidently much higher
than displacement hulls only because the latter are much longer.
The higher volumetric coefficient reflects the fact that planing
designs are not intended for nor are capable of sustained operation
near or below "hull speed" in which their low weight-to-drag ratio
would be prohibitive compared to displacement hulls.
[0035] As reviewed above, the displacement hull has a wave-making
drag component which increases strongly with speed near and above
hull speed, in addition to an approximately constant wetted area
generating friction drag which increases roughly with square of
speed. These drag sources combine into a high total exponential
drag growth near and above "hull speed" which was shown in FIG. 1.
As a result, operational speed-to-length ratios are about one for
commercial ships and somewhat below two for military ships.
[0036] The percent distribution of frictional resistance and
wave-making resistance, often referred to as residuary resistance
because it may include other minor resistance components, is shown
in FIG. 6. It shows that above "hull speed" of 1.34 more than 60%
of resistance is residuary--mostly wave making drag.
[0037] In hydrodynamic contrast, pure planing hulls, having a
dynamic lift roughly equal to weight, and a high dynamic drag
component dependent on a significant angle of attack required for
vertical equilibrium, and hopefully a decreasing friction drag
percentage with speed, operate at speed-to-length of order of 3.5
or more, with low weight-to-drag ratio of the order of 8 or less,
with operations at lower speed-to-length ratios being an
inefficient transient condition, which also have very poor
weight-to-drag ratio.
[0038] Various hybrid vessels attempting to mix displacement and
planing hull characteristics of monohulls have been proposed in the
past in an attempt to arrive at a single ship type capable of
operating efficiently over speed envelope, unfortunately without
much success, as is reviewed below.
[0039] 1c. Semi-Planing Hulls.
[0040] Unlike displacement hulls which have upwardly curved sterns
and curvatures at the bow, causing suction which sinks their center
of gravity with forward speed (increasing their apparent weight),
and unlike planing hulls having mostly flat undersurfaces and a CG
which tends to rise with forward speed, the semi-planing hull
usually has a Vee bottom and, for practical reasons, is heavier
than a pure planing hull. Although the semi-planing hulls can
generate the appearance of a "flat" wake at high speeds, their lift
is generated by a combination of buoyancy and dynamic forces, which
is inherently inefficient. These hybrids are longer and have lower
volumetric coefficient compared to those of planing hulls, but are
nevertheless much higher than for displacement hulls, as shown, for
example, at the middle of FIG. 4.
[0041] The borders of the wakes of semi-planing hulls, as seen from
an aerial view, appear flat and join together at some distance
behind the stern, generating a trailing "hollow" on the water's
surface, which can be interpreted, from the viewpoint of a fish
trained in hydrodynamics, as an virtual displacement hull of larger
length than that of the dynamic waterplane of the operational
semi-planing hull. The conventional semi-planing hull is an
inefficient hybrid: at slow speeds, it has excessive drag compared
to a good displacement hull. It requires very large power to reach
semi-planing speed, at which regime it is not as fast and is less
efficient than a pure planing hull. On the other hand, a deep-vee
semi-planing hull provides smoother ride for a greater payload in a
rough sea, and is more seaworthy than a planing hull. However, it
has a rougher ride than a displacement hull, with less favorable
sea keeping characteristics, and is commercially not viable for
most large maritime applications.
[0042] 1d. Semi-Displacement Hulls.
[0043] As length-to-beam ratio is increased in slender hulls,
wave-making drag decreases. According to Saunders, slender
displacement power boats were common in the 1910s. Later on, the
German Schnell Boote (fast boat), having a round-bottom hull, was
successfully developed as an S-boat for WWII, performing well at
high speeds in the rough North Sea. However, as the length-beam
slenderness ratio of semi-displacement boats is further increased,
the lateral stability and payload capacity is further decreased. In
the extreme, an 8-man rowing shell relies on oars for lateral
stability. With a length-to-beam ratio of about 30, its wave-making
resistance is only 5% of the total at 10 knots, but its
weight-to-drag ratio is only 20, approximately. An appropriate
comparison in aircraft is the modern sailplane with a wing
span-to-chord ratio of 25. It can operate at weight-to-drag ratio
of 40, at 6 times the speed.
[0044] In the limit as the beam of slender hull approaches zero,
wave-drag tends towards zero, but viscous drag subsists and payload
capacity vanishes. Accordingly, recent development of high speed
semi-displacement boats have proposed a mixed lift mode, using
complex lateral or other additions to the slender hull, to generate
a hydrodynamic lift component at higher speeds, in order to
decrease buoyant lift component and its wave-making drag, and to
compensate other shortcomings of the slender hull at high speeds,
for example, lateral instability and/or a tendency for nose high
attitude and its high drag due to lift. As is the case for
semi-planing hulls, their speed potential is less than planing
hulls, and their ratio of weight-to-drag is not very satisfactory,
and in consequence, payload is not large. Although they appear to
have performance advantages over semi-planing near or above "hull
speeds" and are less sensitive in pitch, their complex shapes
appear to have an inherent size limit, as well as a lower speed
potential.
[0045] 1e. Additional Resistance of Monohulls Due In Adverse Sea
Conditions.
[0046] The various types of monohulls reviewed above have different
responses to sea conditions, which sets crucial additional limits
to their efficiencies in most practical operations. This is an
important subject, since it can and does set crucial limits of
operational speed envelopes and impose structural weight and power
penalties which are different and significantly lower than would be
the case for designs of the same hulls operating only for calm
water.
[0047] In this writer's view, the drag and structural penalties in
an adverse sea for displacement and semi-displacement hulls
originate in their inherently unfavorable longitudinal distribution
of volume and of their buoyancy reserves, which are traditional and
perhaps applicable at slower speed envelopes for ships designed to
climb waves and which have inadequate speed margins relative to the
propagation speed of ocean waves. Moreover, the inertia values of
conventional ships would penalize their performance in respect to
the higher speed envelopes, if such higher speeds were otherwise
attainable with conventional displacement and semi-displacement
hulls. Obviously, a breakthrough to decrease the added drag and
weight penalties of displacement-related hulls in a sea is highly
desirable, particularly if it does not incur into the even worse
penalties which planing-related hulls encounter in an adverse sea,
such as their well-known "slamming" in an opposing sea. Slamming
occurs when quasi-instantaneous, large increases of angle of attack
relative to an oncoming wave are encountered, reaching off-design,
very large transient angles, which blunt speed and enormously
increases the structural loads and weight of the hull.
[0048] 1f. Multi-Hulls.
[0049] The wave-making and other adverse drag problems of the
various types of monohulls reviewed above--including added
resistance in a sea--are so serious that considerable recent
efforts have been applied for the development of new multihulls.
Although this field is outside the scope of this document on
monohulls, a few remarks are in order. A pair of very narrow
slender displacement hulls of a catamaran, widely spaced laterally
for stability, have been successfully developed and are being used
at high speed for various commercial applications, especially in
Asia. The calculation of their volumetric coefficients can be
deceptive, since there are two hulls, each with half the weight but
of full length. Hence, each hull has a more favorable volumetric
coefficient than a monohull, but has two such hulls. Published
information on lift-to-drag ratios of modern catamarans are not
readily available. Nevertheless, drag estimates based on installed
power and operating weight indicate that weight/drag ratios of the
order of 10 are feasible for large semi-planing light catamarans at
speeds of 50 knots and ratios of 16 for 25 knots, but with very
small payloads relative to their overall length and overall weight.
These weight/drag ratios are not high and are close to those of
planing hulls, but are achieved at higher speeds than for
conventional monohull displacement hulls.
[0050] Trimarans may have similar characteristics with some
structural gains, and they also have large traditional buoyancy
reserves forward, but only on the center hull. Recent multihull
trends are exploring trimarans with a very long displacement center
hull to retain a low speed-to-length ratio of the center hull, with
small, narrow, lateral hulls at high speed-to-length ratio for roll
stability, and to support a wide deck. Wave-piercing multihulls may
have a center body which has water contact only in swells,
providing the usual large buoyancy reserves in adverse seas, but
permitting wave piercing in middle seas. SWATHS are also multihulls
which rely on totally submerged primary displacement for smooth
riding, with penalties in wetted area and speed.
[0051] These multihull developments and other high speed hull
developments (see, for example, Jane's High Speed Marine Craft)
have so far been restricted to special commercial or military
applications, highlighting the need for ship manufacturers for a
new monohull design. Such has been specified in my Transonic
Hydrofield TH and Transonic Hull TH invention of patent application
Ser. Nos. 08/814.418 and 08/814.417, capable of efficient operation
in subcritical and supercritical speeds as defined therein, with
drawings in which the water level is shown in calm conditions.
[0052] 2. Transonic Hull Characteristics, application Ser. Nos.
814,418 and 814,417.
[0053] As stated earlier, to understand the nature and scope of
present invention, it is also necessary to review, in addition to
the problems of conventional hulls, the limits and potential of the
transonic hull TH and its hydrofield TH of patent application Ser.
Nos. 08/814.418 and 08/814.417, which precede the present
Application in filing date, including a review of results of tow
tank tests.
[0054] 2a. Characteristics and Features of TH and TH.
[0055] The TH is characterized in having a submerged portion with a
triangular waterplane shape with apex forward in static and in
dynamic conditions, a triangular profile, or modified triangular
profile in side view with maximum draft forward and minimum draft
aft, and planar lateral surfaces at large inclination or vertical
to the water. Thus, the submerged portion has a double-wedge volume
distribution with a fine narrow entry angle in planview and a fine
exit angle aft in profile view. Thus, the shape of TH, and its
associated hydrofield TH, is characterized in absence of surface
wave-making sources such as shoulder, midbody, or quarter
curvatures in planview; they have a narrow entry forward which
minimizes the water volume displaced per unit of time, and induces
special inboard underbody flow, favoring flow subduction which
eliminates the conventional wave-making pattern of displacement
hulls, and allows for new types of hydrodyamic ray phenomenon of
very reduced size and an absence of midbody trough. TH has a
favorable anti-planing propulsive pressure component at its
undersurface; favorable contracting streamline on the sides;
favorable gravitational pressure gradients on the hull's lower
surface; broad stern underflow which prevents pitch up and
eliminate stern wave, and favors the recovery of underbody energy
as well as that from following seas.
[0056] Accordingly, a very important feature of TH and TH as
specified in my prior patent application Ser. No. 08/814,418 is the
elimination of the below-water wave-making sources for high speed
operation in calm water within its displacement mode, thus
preventing or reducing the high exponential rise of wave-making
drag which characterizes conventional hulls near and above their
"hull speed." As explained previously, nominal "hull speed" is 1.34
when expressed with speeds in knots divided by square root of boat
length in feet. In this speed range, for example as in FIG. 1, the
wave drag component of total drag of conventional hulls grows
significantly, and hence the total drag grows in a high exponential
manner, typically by powers of the order of three or more,
depending on hull shape, beam loadings, and Froude number range
(Froude number is defined as speed in Ft./Sec. divided by the
square root of gravity acceleration times engaged water line length
in feet).
[0057] Hence, if the principal sources of wave-making drag growth
with speed are removed, as is the case of TH and of TH's archetype
shape of my patent application Ser. No. 08/814.418, then TH's
principal remaining source of drag growth with speed is that due to
friction, it being noted that (a) TH has no pressure drag problems
at the stern since it has a clean water exit, and (b) TH has
greatly reduced form drag, because it has no curved surface to
significantly increase local and therefore average dynamic pressure
along its wetted surfaces.
[0058] Summarizing, it is the objective and feature of TH's
archetype that near and above its "hull speed" while in the
displacement mode, its total drag grows with only the second power
of speed. The displacement operational mode is characterized in
patent application Ser. No. 08/814.418 and 08/814.417 in its
figures related to the supercritical and subcritical speeds. For
example, in TH:
[0059] The wetted surface remains approximately constant for a
given weight;
[0060] The water flow on the hull's sides continue as small rays,
and the lateral wetted surface remains approximately constant, as
is shown in FIGS. 13 and 14 of original application Ser. No.
08/814,418; and
[0061] The undersurface of the hull has an approximately constant
negative angle of attack to the water surface, and actually
contributes a forward propulsive pressure force component, which is
opposing the retarding pressure components of the water acting on
the submerged sides of TH, as is shown in FIG. 13 of original
application Ser. No. 08/814,418 and in FIG. 7 of the present
Application.
[0062] 2b. Tank Test Data of TH and TH.
[0063] Curves from tow tank test of a TH archetype model (no
appendages) are shown in FIG. 8 of the present Application, showing
that, in the supercritical regime, which begins at about the speed
corresponding to the critical hull speed of a conventional
displacement hull, TH's total drag grows substantially with second
power of speed above "hull speed," within the speed limits of the
test, during which hull's pitch angle had no significant change,
and bottom and side wetted surface was observed to have no
substantial change. The drag growth to the second power can only
occur in the absence of growth of wave-making drag within that
speed range. The critical speed of a conventional hull occurs when
the length between the bow wave and its corresponding stern wave is
equal to hull's waterline length, and this occurs at a ratio of
speed in knots to quare root of length in feet of 1.35.
[0064] By way of comparison, the drag behavior of a refined
International America's Cup Class hull (canoe only; no appendages)
tested in same tank at equal length, beam and weight as TH is also
shown in FIG. 8, showing substantially equal drag as TH at the
critical "hull speed" of a conventional hull, but a drag growth
above its "hull speed" greater than the second power and much
greater than TH, the IACC hull having experienced also a
significant increase of angle of attack with speed.
[0065] The test data of FIG. 8 indicates that the IACC hull has 40%
more drag than the TH archetype at a speed-to-length ratio of about
1.55, and 28% more drag at a speed-to-length ratio of about 1.75.
Due to speed limits of carriage, tests of TH model could not
investigate hydrofields at speed/length ratio greater than about
1.8.
[0066] The initial design speed to be selected for the square speed
growth of TH's total drag depends on TH's shape and on its ratio of
boat weight to cube of hull length, and can be lower than the 1.35
shown in FIG. 7, for example, by changing the angle in planview of
the sides of TH or changing the weight. For example, a 20% weight
reduction lowered the starting speed/length ratio of TH's
supercritical speed regime to 1.1, above which drag growth follows
only the second power of speed.
[0067] 2c. Characteristics of TH as to Shapes and Propulsion.
[0068] patent application Ser. No. 08/814,417 as originally filed
included several drawings of critical alternative shapes of the
lower surface of TH below water and the shape of TH above water
surfaces, which were not shown in Ser. No. 08/814,418, and which
are important in relation to the stealth characteristics of the
present invention, and of the hull shape of the present invention
in relation to TH's ability to negotiate and successfully operate
in adverse seas. The review of these previous features and their
extension and improvements under the present invention will be made
in a later part of the present specification.
[0069] 3. Conceptual Inquiry on Conventual Hulls Leading To Present
Invention.
[0070] The above review on the speed envelopes and limiting
characteristics of the various types of conventional hulls covered
in Sections 1-6 of the present Application, and of the transonic
hull covered its Section 7, leads to the following conceptual
inquiries, to which the present invention responds.
[0071] 3a. Considering FIGS. 3 and 4, which shows that three
different types of optimized conventional hulls, having well-known
hydrodynamic regimes such as displacement, semi-displacement, and
planing, are required to operate in calm water in a speed-to-length
envelope of less than 1 to greater than 5, is it possible to design
a single hull capable of operating in that broad speed
envelope?
[0072] 3b. If the answer to 3a is positive, would one expect that
the weight-to-drag ratios of the three types of hull types
optimized separately, efficiently, and covering by segments the
total breadth of speed-to-length ratios of FIG. 3, could be equaled
with a single hull type covering the same total broad speed range,
or at least approached over principal segments of the total speed
range; or could the weight-to-drag ratio of the new hull decrease,
or be improved, at least in part of the broad speed range?
[0073] 3c. If the single new hull type is established, for example,
as in the present TH-II and TH-II invention, capable of operating
over the broad speed range currently requiring two or three
different hull types, each optimized in over 100 years of
development, could that new hull type have penalties in speed and
weight in an adverse sea which are larger than the penalties
suffered by the three types of hulls optimized also for adverse
seas in their respective speed envelopes, or could the penalties
for the new hull be less severe, or perhaps mostly eliminated?
[0074] 3d. Assuming that a revolutionary new hull type achieves the
favorable characteristics described in 3a and/or 3b or to 3c above,
how should it be trimmed and controlled, and by what methods driven
and steered in a calm sea and in an adverse sea?
[0075] The above conceptual inquiry is ambitious, and it has been
focused and investigated, with the transonic hull TH of patent
application Ser. No. 08/814.418 as a starting reference point, as
reviewed below.
[0076] A reformulation of the conceptual inquiries of 3a to 3c is
focused below in more concrete terms:
[0077] 3e. Is there an upper speed range in which practical
operation of TH patent application Ser. No. 08/814,418 in the
displacement mode encounters diminishing efficiency returns?
[0078] 3f. If 3e is the case, qualitative changes or improvements
or methods or discoveries needed and feasible for TH and TH of
application Ser. No. 08/814,418.
[0079] In respect to 3e, the writer first considers the
supercritical regime with absence of wave-making drag growth with
speed. There has to remain drag growth with speed of viscous
origin, imperfectly referred to as friction drag, which for a given
hull size grows necessarily with the second power of speed. Hence,
there could be encountered practical limits due to due to
powerplant size requirements, weight and costs which occur because
power is a cube function of speed growth, even if drag growth of TH
is a second power of speed, since power equals drag times
velocity.
[0080] Moreover, there could be a performance limits as speed
increases, because TH archetype's propulsive pressure force
component in its lower surface shown in FIG. 7a is substantially
constant, because the hull's weight is substantially constant.
Hence, there is a diminishing percentage contribution of the
propulsive pressure force -N sin .beta. shown in FIG. 7a, compared
to overall propulsive needs, which must oppose a friction drag
growth responding to the second power of speed.
[0081] 3g. Diminishing Benefits of TH's Propulsive Pressure Force
With Speed Increase
[0082] The quasi-constant magnitude of propulsive pressure force
component of TH is a problem of significance for TH's overall power
requirement, which is illustrated below with a specific
example:
[0083] Assume a reasonable weight-to-drag ratio of 100 for a 700
foot long TH ship in displacement mode at a speed-to-length ratio
of 1.2 with a weight of 30,000 tons. According to FIG. 72, the TH
hull of application Ser. No. 08/814.418 experiences in this regime
a propulsive pressure force component in its lower surface -N sin
.beta.. The high weight-to-drag ratio indicates that low total
power is required.
[0084] The total drag for the example above is evidently
30,000/100=300 tons at a reference speed of 1.2{square
root}700=31.75 knots. The dynamic pressure based on remote speed is
2,879 lb/ft.sup.2. The gross propulsive pressure force, GPF, on
undersurface is -N sin .beta., according to FIG. 7a, where .beta.
is a negative of the undersurface to remote water. If .beta. is
--4.degree., the GPF=2,097 tons, canceled in great part by opposing
rearward components of pressure forces on sides of TH shown in FIG.
7b. Therefore, the net propulsive force NPF on the undersurface is
by definition much smaller than GPF, and much smaller than the 300
ton total drag. Assume the NPF opposes 20% of total drag, i.e., 60
tons.
[0085] We assume in this example that total drag growth with speed
for the TH archetype corresponds to that of an optimum TH
hydrofield; namely, drag growth is only that due to friction above
"hull speed," and that it increases only with square of speed. This
assumption has been verified by test data ad shown in FIG. 8 up to
a speed-to-length ratio of 2, and is extrapolated beyond that ratio
in this example, in order to determine the effects of increase of
speed in the relative impotence of propulsive pressure force on the
weight-to-friction drag ratio of TH.
[0086] If we double the initial speed to 63.5 knots, the drag would
be four times, i.e., 1,200 tons, the weight-drag ratio decreases to
50 without accounting for changes in propulsive pressure force, and
the speed-to-length ratio increases to 63.5{square
root}700=63.5/26.45=2.40. The corresponding dynamic pressure is
11,516 lb/ft.sup.2. However, the NPF, which remains a constant
function of weight at constant angle of attach of the hull, is now
diminished from 20% to 10% of total drag.
[0087] If we triple the speed to 92.25 knots, the drag would go up
by a factor of (92.25/31.75).sup.2=9, reaching 2,700 tons, and the
weight-drag ratio is lowered substantially to 11.1, with a
speed-to-length ratio 92.25/26.45=3.48. The corresponding remote
dynamic pressure is 25,911 lb/ft.sup.2, and the contribution of NPF
becomes negligible percentage of the total propulsive force
needed.
[0088] If we quadruple speed to 127 knots, the drag would be
(127/31.75).sup.2 higher, i.e., 16 times higher, yielding 4,800
tons, and the weight-to-drag ratio would decrease to
30,000/4,800=6.25 at a speed-to-length ratio of 127/{square
root}700=4.80. The remote dynamic pressure is now 46,064
lb/ft.sup.2, and the percentile NPF contribution is virtually
zero.
[0089] The above analysis permits the determination of the
following limiting characteristics of the TH archetype of patent
application Ser. No. 08/814,418, answering part of the conceptual
inquiry of 3a and 3e of the present application:
[0090] 3h. The friction drag term D for the weight-to-total-drag
ratio at higher speed-to-length ratio reaches very high values
under enormous remote dynamic pressure q. The viscous drag D.sub.f
is governed by the equation D.sub.f=KC.sub.fqA, in which A is
wetted area, C.sub.f is a viscous coefficient dependent on Reynolds
number, and K is a factor to account for form drag and pressure
drag. At speeds-to-length ratios of the order of two to four times
higher than "hull speed," the weight-to-drag ratio of the assumed
TH archetype decreases and could be as low as that of a planing
hull, about 8 or less for the example analyzed.
[0091] 3i. The propulsive pressure force on the lower surface of
TH, which is important in the displacement mode near "hull speed"
and necessarily a function of the apparent weight of TH and the
sine of the negative angle .beta. of TH's lower surface, becomes
less and less significant as percentage of total propulsive thrust
needed to overcome drag as speed increases, since the viscous drag,
which total thrust must overcome, continues to grow with the square
of speed at constant wetted area, whereas changes of weight with
speed, even considering apparent weight increases under subduction
flows at high dynamic pressure, and therefore of net propulsive
underbody pressure forces, are obviously not as significant.
[0092] 3j. The subduction flows--for example, flows f in FIG. 14c
of patent application Ser. No. 08/814.418--consequent of the
negative angle of attack of the hull's undersurface, has the
potential of increasing the apparent weight of the hull and
increasing propulsive pressure force components, but would increase
the wetted area of sides of the hull, which is unfavorable.
[0093] 3k. Benefits of TH With Diminishing Percentile Propulsive
Pressure Force.
[0094] Notwithstanding the diminishing percent of propulsive
pressure force with increasing speed, reviewed under ______ above,
if it were possible to reach high speeds for TH under a
displacement mode with reasonable powerplant cost and weight, it
would have the very important benefit that even if the
weight-to-drag of TH were to be as unfavorable at high speeds as
that of a planing hull, TH, unlike planing hulls, has a very
favorable weight-to-drag ratio at lower speeds, including the "hull
speed" range; and
[0095] Also, a broad speed envelope with comparable efficiencies
could be attainable with a single TH hull instead of two or three
types of conventional hulls, provided trim and control were
adequate for the TH case, and behavior in an adverse sea
acceptable.
[0096] 3l. Summary of Results of Conceptual Inquiries Above.
[0097] The answer to the conceptual inquiry of section 3e is, yes,
there are improvements needed in TH and TH of application Ser. No.
08/814.418 to overcome problems of increasing viscous drag with
speed (causing diminishing results of propulsive pressure force
components. And in respect to inquiry 3d, the answer is also yes,
in respect to trim, control, and effect of adverse seas. The
solutions to these problems, though difficult in the extreme, has
been attained theoretically and experimentally and is covered by
the teachings and embodiments of the present invention described in
the following section.
4. OBJECTIVES OF PRESENT INVENTION
[0098] The objectives of the TH-II and TH-II invention follow from
the need of a solution of the conceptual inquiries, namely:
[0099] 4a. Establish new hydrodynamic conditions and speed regimes
for TH in which weight-to-drag ratio for increasing speed-to-length
ratio beyond 2 have improved efficiency.
[0100] 4b. Achieve objective 5a in a manner that does not
deteriorate the favorable results already achieved for TH under
application Ser. No. 08/814,418 at speed-to-length ratio below
2.
[0101] 4c. Consequent to 5a and 5b extend the speed regimes of
operation of a single transonic hull TH-II, as may be needed with
special shapes, features, powered propulsive means, and various
design devices, to cover, with acceptable efficiency, a broad speed
range normally requiring more than one type of conventional hulls;
for example, the speed-to-length range of a. conventional efficient
displacement hull under 1.35 plus that of a conventional planing
hull above 3.
[0102] 4d. Achieve favorable objectives 5a, 5b and 5c in a manner
and with design characteristics that do not deteriorate in presence
of adverse seas any more than, and preferably less than,
conventional hulls.
[0103] 4e. Achieves most or all objectives above in a TH-II
configuration that is stealthy in respect to radar and other
sensing methods.
[0104] 4f. Achieve the above objectives, or a combination of these
objectives, with hull shapes, trim features, control devices, and
power arrangements that permit favorable operation and maneuvers of
TH-II under various sea conditions, including adverse seas and
winds, to achieve an all weather operational capability.
5. SUBSTANCE AND DETAILS OF THE PRESENT INVENTION
[0105] In order to specify the new speed regimes which extends TH
hydrofield to TH-II, and the innovative improvements, refinements,
and certain crucial characteristics of TH-II, which have been
developed by R&D work of this writer, there is first reviewed
the hydrodynamics and speed regimes of TH of application Ser. No.
08/814,418 shown in FIGS. 10 and 11 of the present Application,
within the scope of the former application:
[0106] 5a. Review of Supercritical Regime within TH application
Ser. No. 08/814.418.
[0107] This is the preferred hydrodynamic design condition of the
submerged transonic hydrofield for speed-to-length ratio near and
above hull speed under application Ser. No. 08/814,418. Its surface
appearance is shown in FIG. 10: the surface flow on the wake region
is approximately flat and tends on equipotential in the
gravitational sense in the region aft of the stern, but it includes
molecular agitation, because of friction below the undersurface of
TH emerging aft of the stern. Nevertheless, region 1 continues to
expand in a unique way, because of its highly directional steady
momentum, indicative of successful anti-wave subduction for optimum
performance of TH. The flow due to the principal volume displaced
by the translating TH emerges principally in region 1, with the
minimal surface alteration appearing as left and right
three-dimensional rays 3 and 5, having the minimal elevation shown
by hump 7 at downstream wake cut 9. This has been observed in tow
tank tests up to speed-to-length ratio of 2, which was a tank speed
limit.
[0108] 5b. Review of Subcritical Regime Within Scope of application
Ser. No. 08/814,418.
[0109] This speed regime is shown in FIG. 11, in which surface flow
fields of TH are approximately flat in region 11. But undersurface
viscosity forces, relative to momentum content of flow at
subcritical speeds, limits the shape and area of the wake at 11 to
a gothic arch type with aft border 11. Rays 13 and 15 have larger
humps. Downstream of flat wake 11, there is some eddy and hump
formations 17 and a central hump 21. In this sub-critical regime,
there may be in some cases drag growth with speed higher than
second power of speed, because of the eddies and elevations, even
though for TH there are no transverse stern wave nor a bow wave of
the type of conventional displacement hulls.
[0110] In both the supercritical and subcritical speeds, the
undersurface of TH in application Ser. No. 08/814,418 is at a
substantial negative angle to the remote flow and experience a
significant propulsive force.
[0111] 5c. Development of Hypercritical Regime for TH-II and
TH-II.
[0112] To achieve operational capabilities of TH beyond the
supercritical range tested, new tests were necessary beyond
speed/length ratio of 2 to verify the theoretical view that the
underbody angle of TH should be governed to change from its initial
large negative angle to the surface, towards a much smaller
negative angle in order to generate a new hydrodynamic
characteristics in which, at constant weight, it was nevertheless
estimated that the lateral wetted surface of TH should be greatly
decreased in the presence of a decreased flow subduction. This
would lead to a more efficient, different 3-D flow behavior with
increasing speeds and dynamic pressures, since there was retained,
with a decreased lateral wetted area, the following:
[0113] A hydrofield and hull without shoulders, midbody or quarter
curvatures;
[0114] Lack of lateral outward flow and spray.
[0115] These characteristics were achieved with new and improved
hydrodynamic characteristics in the tow tank, trading off a
diminishing percentage of propulsive underbody pressure force, for
a significantly reduced drag from reduced lateral wetted surface,
resulting in a higher weight-to-drag ratios than otherwise for
speed-to-length ratios beyond 2 and of the order of 3. This special
different regime is called hypercritical to mark the fact in that
(a) no dynamic lift is possible since the undersurface of TH
remains at a greatly reduced but still negative angle, but (b)
nevertheless there occurs a decrease of lateral wetted surface. The
regime is uniquely efficient and to a critical measure a unique
property of the special triangular planform of TH, and its profile,
under effect of higher levels to achieve the higher dynamic
pressure in hypercritical regime, as will be described later on in
greater detail with aid of FIG. 13.
[0116] 5.d Development of the Transplanar Regime for TH-II and
TH-II.
[0117] In the new model tests, as speed was further increased
beyond the hypercritical with the underbody governed to attain a
very small and critical positive angle which nevertheless provides
significant dynamic lift due to the very the high dynamic pressure
acting on a very large wetted planform, i.e., a low planform
loading, there resulted a fourth hydrodynamic condition and speed
regime, which nevertheless has a substantial decrease of wetted
length of the lower surface of the TH-II hull, compared to the
hypercritical case. I call this regime "transplanar" in that it
retains some lateral in-flow characteristic of the supercritical
regime of the transonic hull; that is, the flow direction does not
generate the predominantly outward flows typical of planing, which
are shown in FIG. 14f.
[0118] Summarizing, in this writer's R&D on transonic hulls,
the operational regimes, which in patent application Ser. No.
08/814,418 were established to cover subcritical and supercritical
cases, are now extended and specified to much higher speed ranges,
named hypercritical and transplanar, which have weight-to-drag
ratios substantially more favorable and require less power than
would be the case if the TH of Ser. No. 08/814,418 were powered to
achieve, in the displacement mode, the same speed/length ratio
range.
[0119] 5e. The Supercritical Regime as a Preamble to Hypercritical
Case.
[0120] FIG. 12a shows, by way of referral, the hydrostatic
(V/{square root}L=O), waterplane 24 representative of a TH having a
length/beam ratio of 4.25 (beam not shown), and stern draft 23 with
a draft-to-beam ratio of approximately 0.015 for a weight/length
ratio (tons/[length in feet/100].sup.3 of the order to 60. The
undersurface has a negative angle .beta. establishing a draft at
the bow much larger than at the stern.
[0121] In dynamic condition above "hull speed," the side elevation
in respect to remote waterplane of TH in supercritical regime
changes to that shown in FIG. 12b. Notice that although dynamic
stern draft 25 is zero, the undersurface angle .beta. and draft at
bow as well as deck angle remains substantially unchanged, but
propulsive pressure 27 is significant. The corresponding surface of
the hydrofield is shown already in FIG. 10.
[0122] 5f. Specification of (for) TH-II Body and TH-II Flow in
Hypercritical Regime
[0123] To increase speed beyond speed/length ratio of 2, this
writer theorized that the higher momentum content of the wake of
TH-II permitted and justified a rearward shift of the center of
gravity, shown in FIG. 13a as an increase in the hydrostatic
(V/{square root}L=O) draft 29 with a draft-to-beam ratio of about
0.02, still retaining a deep draft at the bow. However, in the
dynamic condition, while the hydrodynamic draft relative to the
stern's wake becomes substantially zero in FIG. 13b, as in FIG.
12b, the undersurface angle is reduced to 1 in FIG. 13b,
substantially smaller than f in FIG. 12b. , while negative, can
approach zero. This change of angle of attack is not predictable
with a bow and shoulder wave of a conventional hull (see FIG. 2),
because there is no shoulder wave on TH-II, and its bow wave is
minimal. The small angle .beta. reduces the total propulsive force,
but it was confirmed in new model tests that it reduces also the
viscous or friction drag on the sides of TH. While the surface
appearance of the corresponding flow appeared as in FIG. 10, it has
different three-dimensional flow field components which cannot be
related to planing, as no surface component of the hull has
positive angle of attack with respect to the remote flow, but
nevertheless reduces the wetted area in the sides of TH. The
attainment of this condition, in which hydrostatic weight must be
substantially equal to displaced water, is altered in respect to
FIG. 12b by the reduction of apparent weight due to greatly
decreased subduction, and a decrease of propulsive pressure force
without significant deterioration in surface or wake of the
hydrofield. The new regime is named "hypercritical," and was
attained with propulsive thrust approximately parallel and below
the undersurface located as in prop shaft 33 to provide nose up
pitch up couple with respect to TH-II's drag with arm 37 of
approximately 0.5 units (0.007% LOA). Alternately, if thrust line
is inclined upward as in prop shaft 35, it can provide a lifting
force equal to thrust times sine of angle 39. For example, if
weight-to-drag ratio were 75, drag would be W/75 and a 10.degree.
angle at 39 would result in a lift force of 0.0024W.
[0124] The specifications for FIG. 13b differs from and is improved
in respect to FIG. 12b as follows: large change of angle of
undersurface from .beta. to .beta..sup.1; a large reduction of bow
draft from approximately length 26 to a much smaller value 38; a
substantial reduction of lateral wetted area and of propulsive
pressure on the undersurface, an increase of dynamic pressures and
momentum content on the wake, and an aft shift of center of
gravity, combined with certain effects of thrust line in this case
from propeller but could be water jets as well. The complex
combined action of the changes above produce the hypercritical
regime and results in greatly improved weight-to-drag ratio for
speed/length ratio of order of 3, or more, that is, in the range
usually assigned to larger vee-bottom semi-planing boats. Notice,
however, that the performance in the hypercritical regime has not
impaired the surface appearance of the wake of FIG. 10, but TH-II
now operates in three regimes: subcritical, supercritical, and
hypercritical, and prevents a wake with a significantly depressed
surface.
[0125] The above description of FIG. 13b is feasible for and unique
to the TH configuration because its flat sides are devoid of
shoulder, mid-body, and quarter curvatures which are usual
wave-making sources, and because the maximum beam of TH is adjacent
the stern, and therefore collects the entire underbody momentum
flows and discharges it in flat exit wake with high momentum
content which continues to prevent transverse stern wave
formation.
[0126] A word of caution in respect to FIG. 13b is the limit of
center of gravity shift to the rear, since it has to meet both
supercritical and hypercritical regimes. Wrong choice can produce a
tendency for self-sustained pitch oscillations similar to an
aircraft "phugoid" mode, which can become unstable and divergent.
The CG location for FIG. 13b requires certain limits, reviewed
later on.
[0127] 5g. Specification of TH Body and Flow in Transplanar Regime
for TH-II and TH-II.
[0128] When speed of TH is further increased beyond the
hypercritical regime of FIG. 13b, an entirely new hydrodynamics was
theorized, named herein "transplanar" in that it permits a uniquely
efficient partial dynamic lift condition without the type of
outward lateral flow which penalizes conventional semi-planing or
Jul. 3, 2000 planing, while retaining the transonic hull features
which also yield and permit supercritical, and hypercritical
regimes. The hydrodynamics and hull conditions are described with
the aid of FIG. 14. Before describing FIG. 14, however, a review is
made of conventional planing boat design of advanced design, for
example, that of FIG. 14f, so that the qualitative differences of
the transplanar regime can be appreciated. Conventional planing is
characterized as follows:
[0129] A planing hull below the planing speed sinks at the stern,
increasing angle of attack due to large bow and shoulder waves as
shown on bottom of FIG. 2.
[0130] If the boat's underbody has suitable surfaces and there is
sufficient power, the planing boat climbs over its bow and shoulder
wave and enters the planing regime of FIG. 14f.
[0131] Outward flow 41 in FIG. 14f with lateral spray is a
consequence of lift requirement by momentum change of conventional
planing shapes.
[0132] Minimal planing area Ap shown as 43 in FIG. 14f in contact
with water provides lift with minimum wetted area, resulting in
high area loading, a quotient made by dividing boat weight W by
planing area Ap.
[0133] Relatively high planing angle of attack caused by small area
Ap; results in high momentum drag component due to lift, as was
explained already with the aid of FIG. 5.
[0134] Small planing area Ap, 43, compared to overall area of
hull's planform 43+45, results in high slamming loads in an adverse
sea on area 45, causing high pitch oscillations, amplified by large
hull volume above area 45.
[0135] High beam loading at stern, a quotient obtained by dividing
weight W by beam 47, results in a deep wake and high angle of
attack.
[0136] A disturbed wake comprising, in cross-section view, hollows
49 and protrusions 51, are symptoms of high momentum drag in
addition to lateral flow losses.
[0137] A wake planform that, unless disturbed by propeller
slipstream, has a hollow which usually closes downstream of the
stern with a large hump 53, a symptom of drag.
[0138] As explained earlier, the large area portion 45 and
associated volume above it, which is dry only in calm water but
becomes engaged repeatedly in waves, causes high slamming loads
plus large change of buoyant forces, leading to excessive cyclic
structural loads, severe pitch and heave accelerations which can be
intolerable for occupants and cargo, and require slowing the
operational speed of conventional planing hulls in adverse sea.
[0139] Overcoming all of the above problems of conventional planing
hulls, TH-II of FIG. 14 is shown in its transplanar regime in
profile in FIG. 14b and in planview in FIG. 14a. The contrasts and
large benefits of TH-II's transplanar regime are evident in the
following description:
[0140] There is no shoulder wave on TH over which TH must climb to
enter a transplanar regime.
[0141] Large planing area Ap, 61, compared to small dry planform
area 63, permits the generation of adequate momentum lift with a
small positive angle .alpha., which cannot become large because of
the location of max beam at stern of TH-II.
[0142] Low transplanar area loading, W/Ap, because Ap 61 is
large.
[0143] Inherent low angle of attack .alpha. of the hull, feasible
for adequate lift with low area loading, W/Ap.
[0144] Low momentum drag with adequate momentum lift, due to
inherent small value of .alpha..
[0145] Lack of lateral energy dissipating flows from TH-II in the
transplanar regime, in favor of typical TH's side rays, not
withstanding adequate momentum lift, a unique advantage of the
TH-II planform in transplanar flow.
[0146] Low beam loading at stern, achieved by placing a large
maximum beam at stern, allowing also low area loading.
[0147] Superior low energy wake achieved with low .alpha., low W/Ap
;low W/B.sup.1, lack of outward flow, with low energy rays instead,
and absence of outward lateral spray flows, as is pointed out in
pertinent transplanar claims.
[0148] Excellent behavior in adverse sea because the ratio of dry
planform area 63, to wetted planing area 61, and to total area
63+61, is small in smooth seas, whence the dry volume corresponding
to area 61 is also small, whereby slamming loads and added buoyant
lift in adverse seas produce minimal effects in pitch, thereby
avoiding high structural loads and accelerations, as is pointed out
in pertinent transplanar claims.
[0149] Specifically, FIG. 14a shows in planform a transonic hull
having its archetype triangular shape, similar to that of FIGS. 10
and 11. However, the hydrodynamic regime in FIG. 14a is entirely
different from FIG. 12, and also different from conventional
planing hull. In FIG. 14b in the transplanar regime, the hull is at
a very small positive angle .beta..sup.11, shown with numeral 65,
with a wetted length 61 and a dry length 67. It is evident that,
contrary to a conventional high speed planing hull, the dry area 69
is considerably smaller than 61, which greatly reduces slamming
loads in an adverse sea. Also, volume above length 69 is much
smaller than above length 67, reducing added buoyant forces in an
adverse sea. In a calm sea, surface of wake shows a unique absence
of lateral spray, indeed retaining lateral rays of the type of FIG.
10, which is contrary to, and not possible in, conventional planing
hull. These unique features of TH-II's are the subject of pertinent
transplanar claims.
[0150] Certain critical geometric relations leading to the unique
hydrodynamics and superior sea keeping of TH-II, which apply to the
hypercritical and transplanar regimes, and the x-regime (see later
on), are illustrated in the following example, specified not by way
of limitation. In the example, the numerals pertain to FIG. 14, and
the numbers identified as units could be feet, tens of feet, meters
or other units:
LWL=LOA=numerals 67+69=70 units
B, beam numeral 62=16 units
LWL/B=4.375
Entry planform angle 60=13 degrees
Planing length, numeral 67=35 units
Dry length in FIG. 14, numeral 69=35 units
Hull's total planform area=560 units squared
Waterplane area wetted, subcritical, supercritical,
hypercritical=560 units squared
Dry planform forward transplanar, calm water=140 units squared
Wetted planform transplanar, calm water, 560-140=420 units
squared
% waterplane area loaded hypercritical=100%
% waterplane area with additional load in adverse seas=0%
% waterplane area loaded calm water, transplanar, 420/560=75%,
transplanar
% area with transient additional load transplanar in adverse
seas=140/560=25%
Weight of boat=W
Planform loading=W/420, calm water, transplanar
Planform loading=W/560, hypercritical
Beam loading all conditions W/16
Average free board height, numeral 64=5 units
Volume above waterplane, transplanar=2100 units cubed
Volume above forward dry planform, transplanar=700 units cubed,
partially engaged only in rough water
Ratio of volume forward to volume above waterplane
700/2100=0.33
[0151] The above design criteria and characteristics of TH, though
not limiting, are unique. Moreover, they require, for safe
transplanar operation, a proper location of center of gravity (CG),
longitudinal center of flotation (LCF), and thrust line, such that
the behavior in calm and adverse seas are adequate. The center of
gravity needed to meet the required conditions in transplanar flow
depend on hull shape in planform in profile, and thrust line
location. A good value for CG location for the above example is 28
units measured forward from the stern, i.e., 40% of LWL, with the
thrust line approximately parallel to the undersurface and 1.25
units below it, i.e., 2.85% LWL below it. The above unique features
are characteristics for claims.
[0152] Furthermore, to achieve a transition from hypercritical to
transplanar regimes on TH-II with a stable CG, the corresponding
aft profile shape is shown as 71 in FIG. 14c, for approximately the
last 2.0 units of length of the undersurface, shown as 73, having a
length of 2.5-3.5% of LWL which should be inclined upwards at
approximately -5 degrees, as shown by angle -.alpha.. This is
qualitatively different and contrary practice to profile shape of
high speed planing boats, which recommend opposite downward camber
at stern to facilitate planing without excessive angle of attack,
and also reduce hump drag before planing; for example, to alleviate
nose-up tendency at bottom of FIG. 2.
[0153] The critical importance of hull shape, CG, and control flaps
to be specified in next sections can be better understood by
recognizing the variables involved in pitch equilibrium as
hydrodynamic regimes change from zero speed to transplanar in calm
water and in a sea. Consideration has to be given to hydrostatic
center of buoyancy, hydrodynamic center of buoyancy during hull
motion, longitudinal center of flotation (LCF, area centroid of
waterplane) which changes radically in transplanar regime, center
of dynamic pressure forces due to momentum change, effect of change
of hull's angle of attack on hydrodynamic subduction, the
respective interaction of all the above in calm water and in an
adverse sea.
[0154] For example, in the example reviewed above in which the CG
is 28 units from stern, i.e., 40% LWL, the center of longitudinal
flotation (waterplane area centroid) varies from 23.3 units from
stern (33% of LWL) in supercritical regime, to roughly 15 units
from stern (21% of LWL) in transplanar regime. Accordingly, the
critical distance between CG and LCF vary from (28-23.3) units=4.7
units for supercritical and hypercritical regimes, which is 6.7%
LOA, to (28-15) units=13 units, which is 18.5% of LOA, in the
transplanar regime. An approximate position is shown as numeral 70
in FIG. 14a.
[0155] These important parameters and relationships pertaining to
longitudinal trim, stability, and control have been exemplified for
the transonic hull of the proportions reviewed, with a trailing
flap of the type shown in FIG. 14d described later on, with the
hull having rounded corners between sides and bottom surfaces of
radius 1 unit, which is 6.25% of stern's beam.
[0156] Variations of the hull's geometry in the example above will
alter somewhat the parameters and relations of longitudinal trim,
stability, and control. They are also dependent on ratio of weight
to volume, for example, weight in tons to cube of length in
feet/100. The example given is a guide for ratios in the order of
50 to 85. By way of reference, a ship of 30,000 tons and 750 feet
LWL has a weight-to-volume ratio of 71.1. In this respect, it is
important to distribute the loading of transonic hull to cause a
much greater hydrostatic draft at bow than at stern.
[0157] To realize the unusual features of TH and TH-II if flotation
with a static waterplane were made such that TH's undersurface were
parallel to the waterplane, as is usual for conventional ships, the
center of buoyancy would fall at about 33% LOA, requiring the same
position of CG, it would cause excessive drag in displacement
supercritical regime, and would negate the large distances between
CG and LCF of transonic hull in its various regimes, and would
cause an unstable pitch situation at higher speeds. Also, TH's
stern's wake in supercritical regime would be destroyed. With such
parallel flotation, the remedy to move CG forward for pitch
stability would require a submerged nose bulb on a transonic hull,
which would impair drag and be undesirable in an adverse sea,
resulting in slamming loads and large variations of structural
bending moments at midbody.
[0158] 5h. Stern Devices to Make a Single TH Operational in Various
Speed Regimes.
[0159] To make feasible a flexible and efficient use of the single
transonic hull TH over its entire broad speed range--i.e.,
subcritical, supercritical, hypercritical, and transplanar
regimes--variable geometry stern profile is of critical and optimum
results, for example, with a trailing edge flap at the stern, but
used in a qualitatively different critical and opposite way than
stern tabs on conventional planing or semi-planing boats.
[0160] FIG. 14d shows TH's undersurface with a flat aft profile 75
adjacent stern 77, with a stern flap 76 mounted smoothly at the
corner of surfaces 77 and 75, with an upward flap angle Sf of about
-6.degree., and a stern flap chord of 2.5% LWL. This negative angle
is needed to generate and govern the critical small angle 65 in
FIG. 14b in transplanar regime with a stable 40% CG, and in certain
cases in subcritical regimes, but not desired in supercritical or
hypercritical regimes.
[0161] FIG. 14e shows the stern flap of FIG. 14d installed in the
type of stern of FIG. 14c modified to accept an optimized hull aft
profile. Specifically, there is flat profile aft of hull 78 which
curves gently to the rear in sector 79 of 4.2% LOA, thereby
reducing stern's draft about 0.18, thereby increasing immersed
volume contribution of rear of TH-II, without excessive local stern
draft. At corner 83 there is hinged a stern flap 82 of about 2.1%
chord operated from torque tube 86 by a connecting rod between arm
85 and bracket 84. The flap has an angle of about -5.degree. for
transplanar flow, and optionally for subcritical flow up to about
-8.degree.. However, the flap reverses the effect of downwards
curvature 79 to about zero exit angle at stern flap position 88 for
supercritical and hypercritical regimes, and has a special brake
position 89 which buries the bow of TH and raises its stern for a
drag increment from both sources, especially beneficial for braking
in hypercritical and transplanar speed regimes.
[0162] I have reviewed with the aid of FIGS. 12, 13, and 14, the
specifications for shape, hydrostatic and hydrodynamics of TH in
supercritical, hypercritical, and transplanar regimes, center of
gravity and LCF locations and thrust line locations, planform and
beam loadings, rear profile shape of TH, stern flap for TH and
their combinations, the distribution of dry and wetted undersurface
areas and corresponding volumes, and their effects on hull behavior
in adverse seas. For the latter case, an increase of weight permits
a more aft CG location; for example, for weight-to-length ratio of
76, the CG can be moved back from 0.40 to 0.39, and also at lighter
weight-to-length ratio to permit easier entry to the transplanar
regime.
[0163] 5i. Additional X-Speed Regime of TH
[0164] FIG. 15 shows a new regime which has been developed by this
writer's R&D on a transonic hull. It is of such a peculiar
nature that even its relation to the transonic hydrofield premises
and understandings are not entirely explored, although the absence
of shoulder, midbody, and quarter curvatures of TH remains critical
and most beneficial. But the water-surface conditions appear to
defy full understanding, and is therefore identified as the
X-regime, encountered in the higher range of speeds, testimony of
which are photographs showing the surface conditions specified in
FIG. 15 at, around, and to rear of the stern 91 of TH body 90. The
wake has a flat even depression with a smooth left edge 93 and a
smooth right edge 97 which project rearwards as water extensions of
the flat sides of body 90. Wake cross-sections at 96 and 95 show a
flat surface of wake below the level of undisturbed flat
water-surface areas 92 outboard of depression at 97, and 94
outboard of depression 95. There is no evidence in the wake of rays
projecting to rear of transom 91, except as borders of the
depressed wake zone. For this x-regime, it is noted, TH has a
deeper draft forward as outlined with dash-lines in FIG. 15. The
pervasive flat surfaces of the flow field outside the confines of
the wake, as well as inside the wake, is evidence of an
extraordinary hydrodynamic regime, in which it is possible to
postulate a fully lateral flow component in the wake of V sin 4
with V being boat speed and with 4 being half the planform's bow
angle.
[0165] 5j. Roll Control for TH with Stern and Lateral Flaps and
Bottom Streaks.
[0166] FIG. 16 shows trim and control devices for TH of special
value for turns of TH in the hypercritical and transplanar modes.
On TH 13, there is wide stern 100 having at its lower edge three
stern flap segments hinged at collinear axis 107. The center flap
segment 103 acts principally to provide nose-up trim during a turn,
and is therefore raised up by angle 102 in respect to a projection
of flat lower TH surface 112. The flaps are shown for right turn.
Right flap 101 is raised by angle 104 larger than 102, to sink
right side of hull 113, and left flap 105 is lowered by angle 106
in opposite direction than angle 104, to raise the left side of TH
113. Accordingly, TH banks to the right and the bottom surface of
TH experiences, when yawed to the right under action of
conventional rudder, a centripetal force component to the right,
which generates a curved path to the right, under Newton's second
law. (Rudder not shown in FIG. 16.)
[0167] An alternative turning method is shown in FIG. 16,
comprising a retractable lateral flap 108 hinged at an axis 109
inclined in profile view to have a positive angle of attack .alpha.
relative to the flow on the sides of TH. The deployed position of
flap 108 shown in FIG. 16 causes an added lift on right side of TH
113, and since the left flap 114 remains retracted, the right side
of TH is raised, causing a turn to the left. For rectilinear
motion, right flap 108 is retracted by its actuation piston 111 and
is nested smoothly in depression 109 on the side of TH.
[0168] Another detail of FIG. 16 is the cross-sectional curvature
used at the lateral lower corner of the hull. The right side
curvature corresponds to a local ellipse sector with major axis
vertical and 2:1 ratio used in certain speed regimes of FIG. 14a to
minimize sinking effects of subduction. A different embodiment is
shown at left side with a nearly sharp corner 116, which is best
used for x-regime of FIG. 15. As a consequence, the left lateral
flap 114 can be placed at a lower position on the sides of TH 113,
with more powerful effect.
[0169] The mode of usage of stern flaps of FIG. 16 is described in
tabular form below in which f represents angles relative to the
rearward projection of hull's undersurface 112 in degrees.
1 Flap position Left flap Center flap Right flap Subcritical, -4 -4
-4 straight Hypercritical, -5 -5 -5 straight Hypercritical, right
+2 -7 -10 turn
[0170] Transplanar and supercritical use of stern flaps for right
turns is similar to hypercritical.
[0171] The regimes of use of lateral flaps of FIG. 16 are in the
supercritical, hypercritical, and transplanar regimes, with a
longitudinal length that can be optimized, if desired, for the
preferred speed regime, for example, as outlined below.
[0172] 5k. Lateral Flaps for Hydrodynamic Functions.
[0173] FIG. 17 shows lateral devices which have various
applications, as follows:
[0174] a. Dry deck function: the lateral flaps on TH 120 are
deployed when operating in adverse waters, for example, in presence
of wave 122, compared to calm water level 121. Under these
conditions, a properly designed TH will penetrate the swells with
minimal loss of speed, but there may be some water from the swells
reaching the top of the freeboard during the penetration. This
situation is minimized by right and left lateral flaps 123 forward,
124 at midbody, and 125 aft. The flaps may be similar to flaps 108
in FIG. 16.
[0175] b. Pitch control function. In high speed regimes in chopped
water or in swells, or even in calm water, selective use of lateral
flaps can be used for pitch control; for example, deploying the
forward lateral flap pair 123 only for pitch up, or the aft lateral
flap pair 125 for nose down pitch of the hull.
[0176] c. Lateral control function. Only one flap of midbody flap
pair 124 can be used for roll of the hull without pitch effects, or
only one flap of pair 125 can be deployed for roll towards the
opposite side, which would not have its flaps deployed, and nose
down pitch.
[0177] d. Heave control. In the high speed range, the deployments
of the entire flap set will generate some heave, or the deployment
of midbody flap pair 124 will generate midbody heave adjacent CG
with minimal pitch effects.
[0178] e. Fixed lateral flaps as walking paths: As an alternative
(of lower cost), and at some loss of calm water performance,
permanent lateral flaps can be used for operation in normal and
adverse seas, and also to serve as paths to have crew walk on them
in the fore and aft direction for inspection of window seals for
forward anchor manipulations forward, etc.
[0179] 5l. Roll Control with Vertical Undersurface Fences.
[0180] FIG. 17 also shows a vertical fence-like surface 127, which
can be adapted to be retractable bottom flap for minimum drag in
rectilinear motion. When rudder 126 is rotated, it will generate a
centrifugal force at the stern, say outward of the paper. This will
yaw the stern towards the right. As outward motion is developed, a
lateral water flow component inwards towards fence 127 is developed
which raises the pressure on the right side of fence 127 and
therefore rolls TH right side upwards. The combined action of yaw
by the rudder and roll by fence 127 causes the generation of a
centripetal force on the hull towards the left, causing a left turn
path in accordance to Newton's second law. The centripetal force
has two parts: one is the inward component on the bottom of the
hull, and the other is the inward force on the right side of the
hull. Combined they can generate very tight radius of turn.
[0181] 5m. Unique Size Effect on Efficiency of Full Size TH
Vessels.
[0182] My analysis of my tests, I further discovered a very subtle
but very important advantage in estimating the weight-to-drag ratio
of a TH ship applicable to certain hydrodynamic regimes of TH, as
determined in model tests. The advantage is a unique function of
size increases for TH's hull, which is not present in the increase
of size for conventional hulls. Since the drag growth with speed of
TH in displacement supercritical, hypercritical, and hydrofield
regimes is principally of viscous origin and wave-making phenomena
or drag of momentum change is much less significant over these
speed ranges compared to conventional displacement or planing hulls
in the same speed range, TH's weight-to-drag ratio improves with
increasing size for various reasons; one important reason is that
viscous drag decreases strongly with Reynolds number as size
increase at constant Froude number. For example, if drag
coefficient with increasing scale from model to ship decreases 50%,
and if, for simplicity, the viscous drag were estimated with the
cube of the scale, it would be diminished by 50%, but he
wave-making drag and the weight would be calculated with the cube
of the scale. Moreover, since a wetted area increases with the
square of the scale, there would be a further reduction of viscous
drag. The practical consequences of TH's reduction of wave-making
drag in displacement mode in model tests is that the W/D ratio of a
TH ship predicted from model tests can be estimated to be 20% or
more than that predicted from model tests of a conventional
displacement ship at same speed, size, and weight.
[0183] 5n. TH Shapes for Solving General Problems in Adverse
Seas.
[0184] Ships and displacement boats have been designed in the past
and present with substantial buoyancy reserves, and these are
larger from about midbody up to the bow, which reserves are
transiently engaged in adverse seas, to raise the ship's bow when
encountering waves. Even displacement ships such as destroyers
having a sharp entry at the bow at waterplane level and narrow
waterplanes are nevertheless flared outwards and forward above
waterplane to provide buoyancy reserves, as well as permit open
decks forward protected from adverse seas by fences above deck
level.
[0185] Monohulls with vee bottoms and planing boats also have
substantial buoyancy reserves and planing type surface reserves
from midbody to the bow, for the same purposes.
[0186] It has also been the practice of conventional ships and
boats to place heavy components amid-ships, to reduce pitch
inertia.
[0187] The TH design departs from, and is contrary to, these
traditional monohull approaches in respect to shapes and volumes
for adverse seas, with several important departing TH design
features, exemplified in FIGS. 18a to 18g.
[0188] FIG. 18a shows planview 130 of TH with a length of 70 units
and max beam aft of 16 units. FIG. 18b shows side view contour 132
above static water 134; and submerged profile line 136. FIGS. 18c
to 18g show cross-sections of TH. The following unique features are
noted:
[0189] A very sharp total entry angle in planform into waves at all
levels above and below waterplane as shown in FIG. 18a, and
confirmed by cross-section 18c, 18d, 18e.
[0190] A reduced free-board and profile height above static
waterplane in the forward third of hull as shown in FIG. 18b.
[0191] A greatly reduced volume in forward region of the hull above
static waterplane, evident in the transverse cross-section FIGS.
18c to 18f.
[0192] A traverse cross-sectional shape distribution above static
waterplane in the forward region of the hull that has falling
shoulders or an inverted vee shape to dissipate vertical loads from
waves being pierced, as shown in FIGS. 18c to 18f.
[0193] An enclosed habitable volume in the forward portion of the
hull to permit piercing of waves as shown in FIGS. 18c to 18f,
instead of conventional designs taking in water on top of an open
forward deck.
[0194] The specific shapes of TH successfully tested in adverse
seas are shown in FIGS. 18 reviewed above, characterized further in
the following:
[0195] In FIG. 18a, an entry angle extending to the sides of hull
below and above waterplane at total angle 138 of approximately
13.degree., over the entire length of the hull
[0196] Low profile with vertical freeboard forward of approximately
4.2% of the length of hull at 80% station from stern, as in FIGS.
18b and 18d
[0197] Cross-section of hull above waterplane with inverted vee as
in FIGS. 18d and e, or inverted U as in FIG. 18f, with a smooth low
overall profile with a maximum height above waterplane of
approximately 7% of overall length.
[0198] A critical parameter is the resulting volume of buoyancy
reserve in the forward region of the hull above calm waterplane 134
which can be displaced as a transient condition, for example,
during a transient diving encounter into a large wave, such as wave
131 in FIG. 18b. This additional volume should be related to the
water volume displaced by the weight of the ship in calm water.
Successful tests of TH have been made with volume ratios in the
order of 13% for the additional volume between 80% station and bow
in FIG. 18b, and on the order of 32% for the additional volume
between station 57% and station 80%, with a hull's center of
gravity at approximately 40% station. These ratios were obtained by
graphic estimates which are necessarily rough in nature, and can be
refined by computerized calculations with software having wave
simulation, although the latter criteria is incomplete because the
asymmetry of the forward aft area of waterplane. These ratios
result in minimum heave and pitch disturbances.
[0199] Referring bag to the TH-II planform and profile in FIG. 18,
it is very important and critical to clarify that the dynamic
loading at high speeds of the hull, for example, under action of
wave 131, is considerably smaller than conventional very slender
boats, such as that shown in Sea Horse publication of November
1994, for the following reasons:
[0200] At high speed, TH has near-zero or a very small angle of
attack such as in FIGS. 13 and 14, and therefore the change of
vertical momentum of TH is much smaller than with very slender
hulls having dynamic lift assist and which at speed tend to ride
nose high with a large portion of the hull's dry area and volume
exposed to wave's impact and therefore capable of generating very
large loads.
[0201] Furthermore, the planview of TH is much sharper for a given
hull beam, because it is triangular with max beam at stern, rather
than with lenticular sides with max beam near midship, as is shown
in other U.S. patents. Thus, for a given profile, the volume of
buoyancy reserves of TH is less in forward region.
[0202] Cross-section forward has an inverted vee shape to prevent
extremely high local loads under dynamic water impact when piercing
a wave or from waves breaking on top of the hull such as would be
in the case if, instead of having an inverted vee, there would be
an inverted cup.
[0203] With TH geometric properties, it becomes especially
advantageous to distribute the heavy components of the ship to
maximize the longitudinal moment of inertia, i.e., that about a
transverse axis through the center of gravity at 40% station in
FIG. 18b, and an alternative one through the longitudinal center of
flotation at 33% of station in FIGS. 18a and b, although the latter
criteria is incomplete because of he asymmetry of the fore and aft
areas of waterplane. Placing powerplant, heavy weapons, fuel tanks,
and other heavy areas adjacent bow and stern are important. The
model tests have shown very favorable results with as much as 40%
of the total boat weight assigned near the hull's ends. This may
necessitate, in certain cases, the unusual powerplant distribution
shown in FIG. 19.
[0204] 5o. Weight Distribution of TH.
[0205] FIG. 19a shows in side view a TH 150 having a forwardly
located engine 152 driving a midbody propeller 154 driven through a
conventional shaft, both protected by vertical fin 156 which can
also provide good tracking and centripetal forces in a yaw. At the
rear are a pair of left and right engines, only one of which is
shown as engine 156. It drives a vertical shaft 158 which is
submerged in rudder 160 to drive propeller 168 mounted on the
rudder, or separate and ahead of the rudder. The power plant system
can comprise therefore three engines. Fuel tanks 151 and 153 are
also located at extremes of the hull, so that heavy components
maximize pitch inertia of the hull. The upper part 161 of hull 150
is similar to that of FIG. 18 in the forward half, but in the aft
half there is an open deck having two additional features which
combine uniquely with the broad stern beam: one is a helicopter
landing pad 164 above deck. Another is a stern garage 170 in FIG.
19b for launching and retrieving an auxiliary powerboat 172, while
the TH ship is in motion. FIG. 19b also shows how to fit right
engine 156 and tank 151 on right side of garage with left engine
174 with left tank 176 on left of garage, and stairway 178 out of
garage. All of which is uniquely possible by max beam at stern.
[0206] 5p. Stealth and Low Observable Characteristics of TH
[0207] Returning to FIG. 18, I now describe-the stealth anti-radar
surface arrangement of Th above waterplane 134. Specifically, the
envelope of the hull follows a faceted criteria of low radar
signature, which I review on the right side of the hull, having
flat panels shown in the cross-sectional views 18c to 18g,
comprising flat panels 138 inclined at about 45.degree. to the
waterplane, flat panel 139 inclined at about 90.degree. to the
waterplane and top flat panel 140. Thus, directly from above the
hull presents only three panels: 138 left and 138 right, both
inclined at 45.degree., and flat panel 140, approximately
horizontal. From an oblique side view from above on right, there
are only three significant panels: 138 right, 139, and 140. From
the front view, by its nature, the TH shape is extremely stealthy.
From the rear, it's detectability is limited to four dispersing
oblique surfaces: 141 and 142 on the right, and corresponding pair
on the left, without numerals.
[0208] 5q. Center of Gravity and Waterplane Centroid of TH
[0209] Other important details in FIG. 18 is the center of gravity
145 CG location at 40% of hull length from stern, and the
longitudinal center of flotation 143 LCF at 33% of length from
stern, really a waterplane centroid, providing thereby a dynamic
stabilizing arm between CG and LCF of 40%-33%=7% of boat length in
displacement mode, as already mentioned for other figures and which
is a radically larger number than possible for conventional
displacement ships, and is uniquely feasible with, and advantageous
for, TH. In the transplanar mode, this margin is increased
substantially above 7%, and can reach the order of 14% in reference
to transplanar LCF 143TP.
[0210] 5r. Undersurface Shape and Construction Methods for TH
[0211] As specified in original patent application Ser. No.
08/814,417, modern construction methods using composite, or stamped
metal sheet and/or welded plates can be used for TH; also wood can
be utilized.
[0212] However, TH can be designed for low cost fabrication
methods, taking advantage of its unique simplicity of shape,
especially with the use of prefabricated composite sheets, marine
plywood or sheet metal, which can be used in flat elements, and/or
with gentle single curvature panels, to obtain hydrodynamically
smooth surfaces.
[0213] Original patent application Ser. No. 08/814,417 also
specified FIGS. 20a, 20b, 21, 22, 23, 24, 25, 26 and 27, without
change (except sequential numerals and minor grammatical
corrections).
[0214] FIG. 20a shows an isometric bottom view of TH comprising
flat rectangular lateral sides 200 and 203, converging at bow 204
in triangular planform; a flat triangular bottom 205, with
centerline 202; and a flat stern region 206. This shape, with a
wetted triangular profile, as reviewed earlier, transcends
wave-making drag of conventional hulls , but may have excessive
wetted area and viscous drag.
[0215] FIG. 20b shows TH refined with simple construction methods
to reduce viscous drag by introducing additional triangular flat at
the undersurfaces of the hull, modified to have a hull with flat
trapezoidal sides 221 and 223 converging at bow 224. The
undersurface comprises three triangular flats 229 at left, 225 at
middle with centerline 222, and 227 at right. The triangles
terminate in flat stern region 226.
[0216] FIG. 21 shows a pure triangle surface development of TH in
which its sides and undersurfaces of the hull are defined by
triangular flat surface elements 231, 232, 233, 234, 235, and 236
converging at bow 237 and terminating at stern region 238.
[0217] FIG. 22 shows a shape developed from FIG. 21, but more
refined to further reduce viscous drag. Its undersurface and side
surfaces comprise main quasi-triangular surfaces 241, 243, 245 and
247, between some of which there are trapezoidal or triangular
fairing strips 242, 244 and 246, all of which blend in bow 248, now
extending at an angle 250 to the vertical to reduce the rate of
volume engagement per unit of time as function of draft. Surfaces
242, 243, 244, 245 and 246 extend rearwardly towards a flat transom
249 of little depth, shown vertical only for clarity of drawing.
The upper deck surface adjacent to the transom is now at an angle
240 to the forward deck surface, defining a rearward sub-triangular
termination to side surfaces 241. For ease of construction, in FIG.
22 elements 242-246, and even 244, could be rectangles of very high
aspect ratio, the principal gain being lower cost of
fabrication.
[0218] FIG. 23 shows a variation of TH, in which, when there are
practical restrictions to hull length and/or hull beam (such as
design rules, or available dock length for docking, or maximum beam
for trailering purposes, all of which may impact on water length
and/or righting moments for a given displacement). It may be
necessary to modify the TH archetype of FIG. 19. For example, hull
shape shown in FIG. 20 meets greater displacement for a given
maximum beam with a modified quasi-triangular arrangement for a
given maximum beam.
[0219] Specifically, in FIG. 23 the main component of the hull
comprises a main triangular body of length 254 extending between
bow 251 and the triangle's base station 252 in the manner shown in
previous figures. But, in FIG. 23 the hull is now extended aft with
an aft body of length 255, extending between triangle's base
station 252 and stern region 253. Note that although the extension
is quasi rectangular in planform at deck level along 255, the
submerged undersurface remains flat with main triangular surface
components 256 and 257, and flat near triangular surface components
258 and 259, extending to transom 260.
[0220] A special feature for TH shown in FIG. 23 is the use of
vertical or anhedraled winglets 261 and 262 at the rear and of the
hull, to extract energy from the fan-like submerged flow field
along surfaces 258 and 259, thereby increasing the hull's effective
beam at transom 260, without increasing its geometric trailerable
beam for the case of vertical winglets. If these winglets are
inclined by an ahedral angle as on the left side of FIG. 23, they
can begin to act as rear hydrofoils supporting part of the weight
otherwise supported by hull extension 255, and they can also serve
for directional control.
[0221] It is noted that in FIGS. 20 to 23 the submerged
undersurface have been flat or nearly flat, guided by surface
elements and hydrodynamic waterplanes having triangular features,
with decreasing draft and increasing beam as the water moves
towards the rear, setting a favorable gravitational hydrostatic
pressure gradient for the flow which remains active in hydrodynamic
condition.
[0222] The development of shapes using flat surface components
reduces fabrication costs and helps illustrate design features.
Penalties are small by reason of unique cooperation between the
simple shapes of the TH archetype permitting use of flat and/or
single curvature elements to attain a reasonably smooth double
wedge TH body.
[0223] 5s. Some Special TH Shapes for Sailboats
[0224] FIG. 24 shows a further variation of the TH archetype, this
time modified in order to meet arbitrary rules such as IACC:
minimum girths, and underbody slopes which require bow and stern
overhang from the waterline length at centerplane. For TH, the
stern overhang can be important, as is exemplified in FIG. 24,
developed from 23. Specifically, the TH archetype extends on main
hull body length 274, from bow 271 to maximum beam at triangle's
base at station 272, having a center line 276 on its undersurface.
Aft hull extension 275 extends from station 272 to 273, for the
centerline on its undersurface has to be inclined by angle 276 for
rule overhang purposes, no more than approximately 12.degree.,
defining a 200 mm distance 280 at an aft girth station 279. The
stern is Vee-shaped in planform, to permit a suitable girth 282
within IACC rule.
[0225] FIG. 26 shows my archetype hull in inverted position for
clarity, having lower surface triangles 290r and 290L, and a
modified stern with inverted Vee or diagonal transom sides 293 and
294, defining an internal a triangular stern exit with a forwardly
oriented apex at centerplane. This reduces wetted area without
decreasing heeled waterline. Netting 291 supported by tubular
member 292 effective "deck" area, but with a decreased hull
weight.
[0226] The hull (canoe) of FIG. 26 is designed to be able to
operate under sail, engaging left or right hydrodynamic waterplanes
on one or the other half of its undersurfaces, 290L or 290R, which
decreases wetted area. Planing may be desirable if it increases
hydrodynamically the hull's hydrostatic righting moment, or
otherwise decreases total drag.
[0227] FIG. 27 is a unique development of this writer's TH hull
with a very deep-v transom cuts 296 and 297 defining a triangular
recess for flow exit at the stern. The deep-V geometrically
parallels, with stager, the triangular bow entry of the hull. Under
sail when upright, it has decreased wetted area. When upwind or
reaching, the hull of FIG. 27 should be heeled to one side or the
other, establishing engaged hydrodynamic waterplane shapes 297a
when rear end 297 is engaged by the water, and 296a when side of
196 is engaged. A large weight savings and wetted area reduction
results from the deep Vee, with a large effective "deck" area
retained by bar 298 and netting 298a.
[0228] FIG. 27 also shows special appendages for TH hull under
sail, comprising a rotating fin keel 299 which can be moved along
arc 299c, and right and left rudders 299b and 299a, either of which
is engaged when sailing upwind; for example, 299b when side 197 is
engaged according to waterplane 297a. In that case, the trailing
edge of both fin 299 and rudder 299b should be rotated to the right
in the figure, or clockwise. Rotating fin keel 299 could be
substituted by a non-rotating narrow fin and a large rotating flap.
Foil rotation permits operating the TH hull at a trans-leeway angle
shown in FIG. 28, instead of the usual leeway angle, with
decreasing hydrodynamics drag due to rectilinear leeward canoe
shape and increasing sail thrust by increasing gap 300 between jib
301 and main sail 302 when sailing close hauled. Also shown in FIG.
28 are the corresponding rudder foil angle positions, with 299a out
of the water.
[0229] FIG. 28A shows a multihull using two parallel TH hulls 301
and 303 which at supercritical speeds and above have no wake
interference in the vicinity of the vessel, as can be seen by
inboard ray patterns 309 and 311. Outboard rays are 313 and 315.
The hulls are driven by propellers 305 and 307. Hence, the
hydrodynamic TH benefits are retained in full.
[0230] FIG. 28B shows a radically different multihull approach
exemplified with TH hulls, but applicable to other hulls.
Specifically, right and left hulls 310 and 312 have their
longitudinal axis of symmetry outwardly oriented in a toe out angle
in respect to a general axis of symmetry. As a consequence,
outboard rays 320 and 322 have diminished size and drag effect,
with less wetted side surface, but inboard rays 324 and 326 tend to
interfere tending to raise water level and drag, and increase
inboard wetted surfaces. This may be recovered by favorable
interference at the rear end of hulls 310 and 312. However, the
multihull of FIG. 28B is equipped with water accelerating
propulsive means 330 shown as a battery of five water jets between
the hulls which when operational recover certain energy content of
rays 324 and 326, reducing their tendency to increase water level,
reducing their drag contribution, reducing inboard lateral wetted
surfaces, and increasing efficiency of thrust generation in that in
addition no boundary layer from hulls falls into the powerplant.
The clean accelerative flow appears as 332.
[0231] FIG. 28C is a trimaran with three TH hulls 340, 342, and
344, but also could be conventional hulls with no toe out, since
for either case, the two propulsion batteries 346 and 348, each of
the type in FIG. 28B, which provide unique interactive benefits of
decreasing drag and increasing thrust. For smaller multihulls, the
power groups can be made with batteries of outboard marine engines.
The following additional remarks pertain to FIGS. 28A: For a given
overall length and weight, the catamaran configuration offers
unique benefits to TH, in that the beam loading, for a given hull
length and entry angle, is halved, facilitating the more rapid
transition from supercritical to transplannar hydrodynamic regimes
on both hulls.
[0232] In respect to FIG. 28B, the benefits of toe out angle need
not be restricted to hulls having longitudinal axis of symmetry,
and an asymmetric planform can replace the angle of tow out, or
diminish it, it being understood that the asymmetric shape of the
hull would be symmetric in respect to a central longitudinal
line.
[0233] In respect to FIGS. 28B and 28C, the word "batteries" is
used to indicate a single flow propulsor, or multiple flow
propulsion, mounted between the hulls of multihulls of the referred
figures, for example, the five water jets of group 332 in FIG. 28B,
or the pair of two water jets 346 and 348 in FIG. 28C.
[0234] I refer now to FIG. 29 showing a long center TH hull 360 and
the much shorter lateral TH hulls 361 and 362 forming a TH
trimaran, with unique cooperation between the three hulls
components, exemplified in the following quantified analysis:
Lc, length of center hull=350 feet
Lc/Bc=7
Bc, beam center hull=50 feet
{square root}Lc=18.70
Speed/length ratio, V/{square root}L=4.27
Speed=80 knots
Lo, length of outboard hulls=125 feet
Bo, beam of outboard hulls=25 feet
Lo/Bo=125/5=5
Speed=80 knots, same as center hull
V/{square root}Lo=80/{square root}125=80/11.18=7.15
Ratio of lengths Lc/Lo=350/125=2.8
Ratio of speed/length ratios, center/outboard=4.27/7.15=0.60
Lc/Boa=350/175=2, where Boa is overall beam
[0235] Important hydrodynamic characteristics of FIG. 29 are as
follows: minimal interference drag, for example, between non
colliding principal rays 363 and 364 good alignment of hydrostatic
centers of buoyancy of the three hulls for good hydrostatic lateral
stability lower length/beam ratio of outer hulls, compared to
center hull, to decrease beam loading and therefore the induced
drag of outer hulls.
[0236] The importance of the latter feature is indirectly
exemplified in FIG. 30 showing drag curves, which is qualitative in
nature. Curve (a) shows the drag growth between speed/length ratios
of 4.27 and 7.15, which is large at constant beam loading, but when
beam loading is decreased by increasing beam relative to length,
and/or by decreasing weight, as in curve (b), drag is reduced.
[0237] A different and less favorable situation is shown on the
left side of trimaran of FIG. 31, having a slender central
displacement hull 371 with a high length/beam ratio to facilitate
wave piercing, and a left lateral hull 373 also of slender type,
with a similar length beam ratio. Their first problem is a high
friction drag which increases with square of speed, as shown in
qualitative curve (c) of FIG. 30. When operating at a speed/length
ratio of up to about 3, drag is not excessive, and decreasing
weight has small benefits as shown in curve (d). However, when
speed increases to speed/length ratio of 5, which is the case for
hull 393, friction drag level becomes unacceptable in both curves
(c) and (d). Also, wave making drag becomes significant, due to
shoulder curvature in the planform of conventional hulls. Thus, the
shorter length of hull 373 has an inherent problem.
[0238] A quantified example of FIG. 31 is presented below:
Length of conventional center hull=350 feet and its square root is
18.7
Speed/length ratio, V/{square root}L=3
V=3.times.18.7=56 knots
Beam of center hull=30 feet
Length/beam ratio 350/30=11.7
[0239] The outboard hull of conventional design has a very
different hydrodynamic situation:
Length=125 feet; its square root is 11.8
Length/beam remains same as center hull 11.7
V=56 knots, as in center hull
However, speed/length=56/11.18=5.0
[0240] Its drag level at speed/length ratio of 5, for hull 373 is
therefore very high along curve (c) of FIG. 30, even if it had
smaller size and weight compared to center hull, for example along
curve (d).
[0241] In theory, a conventional planning hull, such as 375 shown
in dash lines in FIG. 31, could have less drag in the planning
condition at 56 knots, compared to conventional displacement hull
373 at the same speed, for example as shown in curve (e) in FIG.
30, but only in flat water. In normal ocean conditions, or in
adverse seas, planning hull 375 would have unacceptable drag due to
wave encounter, and high structural load as well rendering it
impractical.
[0242] A more favorable situation applies for a trimaran hull using
a slender central displacement hull such as 371 in FIG. 31 at
speed/length ratio of 3 but with outboard hulls of transonic hull
shape such as 377 in FIG. 31 of same or similar length as 373, but
with a wider beam. Hull 377 could operate at high speed/length
ratio of about 5, but its drag on curve (a) or (b) in FIG. 30 would
be much lower than the conventional outboard displacement hull, as
curves (c) and (d) shown in FIG. 30 for the speed/length ratio of
5.
[0243] As stated earlier, the drag curves of FIG. 30 are
qualitative in nature, as their precise value for central and
outboard hulls would depend on relative weights, beam loadings,
length/weight ratios, and similar characteristics which are
dependent on specific design choices. However, FIG. 30 are useful
guides for a person familiar with multihull design theory and
practice, to guide specific design choices.
[0244] In the prior review of problems of trimarans, the effect of
rough ocean conditions has been mentioned in respect to wave
piercing and structural loads, which in case of planning outboard
hulls could be of the "slam load" type. This problem is alleviated
if the wings supporting the outboard hulls are hinged at their
root, for example by hinge 368 with toe in FIG. 29, or hinge 369
parallel to center line of FIG. 29. This type of arrangement, seen
from the rear in FIG. 32, could be applicable to conventional, or
THE, or planning hulls. This generic case shown by way of example
in FIG. 32: wing 380 is hinged at its root hinge 381 to permit
angular motion 383 while its outboard hull 381 accepts lateral
ocean wave 382 with minimal slam loads and drag growth due to wave
encounter. Hull 381 could be of slender displacement type, or
alternatively, conventional planning, or TH type. Wing 380 is
mounted on center hull 379, which could be of any of the above hull
types, at hinge 381. Its angular excursion could be powered by the
lateral wave, and/or by hydraulic piston 383, or a combination of
power and damping by a hydraulic piston system similar to 383.
[0245] The prior FIGS. 28 A to 32 described TH multihull
applications to large craft, but also representative of medium size
craft such as passenger boat, ferries, and military patrol and
coast guard boats, by scaling down as appropriate.
[0246] Moreover, TH multihulls are not size dependent, and can also
be applied to small boats and man powered craft with or without
auxiliary or emergency power devices. This is exemplified in a
kayak type craft specified first as a monohull, with additions of
lateral hulls thereafter.
[0247] Specifically FIG. 33 shows a monohull manpowered kayak type
hull 390 with flat sides and faceted top surfaces for ease of
manufacture, and/or assembly in the case of a kayak kit. Open
cockpit is shown as 391 and stern at 392. While manpowered speed
may barely reach supercritical range, the TH configuration as kayak
offers three important benefits: one is the feasibility for a
person to climb aboard in deep waters from the stern end, without
rolling the hull, improving in this unique way safety in an
emergency deep-water condition. Another is the ability of an arm to
execute paddle motion from a narrow cabin, enabling the arm to
remain close to the body, while retaining a broader beam for
lateral stability aft of the cabin. This is directly contrary to
usual kayak design, in which a maximum beam is at the cockpit. The
third advantage is smoother ride with less drag growth due to
encounter with a choppy sea surface, due to the very sharp entry
angle of the hull. The inch dimensions of a TH kayak are shown
below by way of example:
length overall=162
water line length=162
maximum beam at stern=35
[0248] The flat sides of FIG. 33 can be generally vertical.
Alternatively, they can be inclined outwardly, for example, by
changing the bow angle to 393, similar to 395. This slides the
deck's planform 394 forward relative to planform of bottom surface,
signified as 396, thereby slanting the flat right side 397, and the
opposite side outwardly, as shown in FIG. 34.
[0249] Returning to FIG. 33, its typical crosssection 348 is also
shown in FIG. 35 as 398. However, FIG. 35 also shows hinged lateral
bodies to enhance lateral stability when deployed, by way of
example, on a TH hull, but applicable to all types of kayaks and
similar craft. FIG. 35 shows retracted right body 400 hinged at
axis 401 substantially above waterplane 402, so that the body 400
does not interfere with water surface 403 when the craft is in
motion. However, when lateral stability needs to be increased, for
example at slow speeds, or stationary, or in adverse seas, it is
deployed to position 400', with its lower surface when deployed
adjacent the water's level 402. When 400 is in position 400', the
center of buoyancy of the craft will shift asymmetrically when the
craft is heeled or rolled, volume of 400 is submerged, generating a
restoring moment to the craft, for example with water level 403
representative of the heeled condition.
[0250] FIG. 36 shows an isometric view of the body of FIG. 33 with
lateral stability bodies of FIG. 36 in the 400 retracted condition.
FIG. 37 shows the same craft with the stability bodies in the
deployed 400' condition.
[0251] Prior discussion of manpowered TH type kayak has mentioned
lateral stability issues and auxiliary or emergency propulsion.
[0252] Lateral stability can be improved for a TH kayak, or any
type of kayaks, by means of an asymmetric auxiliary hull, or "proa"
configuration, such as shown in FIG. 38 with main hull 405, and a
lateral or auxiliary hull 406, supported by wing 407. Body 405
should be small so as not to generate drag and weight. Hence, there
is special benefit for 406 to be of TH type, because at or near
critical speed of main hull 405, auxiliary hull 406 is evidently
operating in transplannar regimes, due to its short length.
Moreover, it can encounter water chop of large size relative to its
length and beam, which means that the TH offers a separate gain,
compared to conventional slender displacement shape used for a
lateral hull. The TH shape of auxiliary body 46 is specified in
FIG. 39.
[0253] Specifically FIG. 39 shows the top view of main TH hull 405,
side wing 407 and lateral body 406, with the corresponding side
view in FIG. 40. Coordinates and dimensions are in inches for a
manpowered craft, but could be feet for a small ferry or military
craft, and meters for a larger craft, with different top
surfaces.
[0254] The coordinates and sections of lateral TH body 406 are
shown in FIG. 41. The X (longitudinal) and Y (lateral) coordinates
can be increased for a lateral body of greater buoyancy, for
example, with a factor up to about 1.6 and the X coordinates for a
more slender body, for example, with a factor of up to 2.0,
approximately, without change in principal TH hull. The asymmetric
shape is designed to reduce tendency of adverse roll on a lateral
sea.
[0255] FIG. 42 shows a TH trimaran with auxiliary or emergency
propeller, the inventive aspect of which is described below:
[0256] The use of air propellers, ducted propellers, and air fans
for moving water craft is known, but has been restricted to special
fields, for example boats for use in swamps and shallow waters,
usually with hulls having rectangular planforms and large beams,
with length to beam ratios of approximately four. Air propellers
have also been used on ground effect machines, also of similar
rectangular planforms, capable of operating over the water or land,
such as Hovercraft. Moreover, air propellers have been proposed and
used for propulsion of hulls of seaplanes, which are slender but
have wing aerodynamic lift at high speeds.
[0257] On the other hand, manned powered watercraft such as rowing
shells, kayaks, and similar boats have used oars, paddles, and even
the interesting moving fins as used in the very efficient
propulsion unit of Hobie Mirage kayaks. All these boats are
slender.
[0258] Kayaks and similar boats have also considered the use of
marine propellers powered by leg motion, as shown in the internet
under various names, and even the use of electric driven marine
propellers as auxiliary power plants, or as emergency power plant,
or as alternative power plant, requiring batteries to drive the
electric motors which drive marine propellers. One serious
impediment is encountered when beaching such manpowered craft with
marine propellers protruding below the surface of the water,
normally requiring that they be retractable, which adds complexity
and cost to such craft. They also add drag when motion is
restricted to oars or paddles, and batteries of standard type,
though low in cost are very heavy, and can reach the weight of an
entire single place kayak. However, air propellers to provide
auxiliary driving thrust with battery power of slender craft is
unprecedented, until the present invention.
[0259] Hence the present invention pertains to the use of
aerodynamic propellers, or ducted propellers, or fans, hereafter
referred to as aerodynamic impellers, in an unprecedented and
unique application for slender manpowered vessels, as alternative,
auxiliary, or emergency powerplants, using batteries which can be
charged on shore, or charged/recharged with solar panels on the
surface of the manpowered craft.
[0260] Special slender TH boat configuration which provides new
unique features are specified in FIGS. 42 and 43. The principal
features of FIG. 42 are as follows: Principal TH hull 409 support
lateral wings 411 and 410, which in turn support outboard TH hulls
413 and 412. Rear deck 414 supports electric motor 420 which drives
air propeller 415 using battery 421.
[0261] The large upper surface area of the TH trimaran should be
used for solar panels in the figured shaded area 416 (top of
forward deck), 417 (top of wings), and 418 (top of rear deck), to
charge batteries when on route on top of a car or on a trailer,
when stationary on a beach, or when rowing. The inclined panels 416
and 418 have a shallow angle, up to 45.degree., to optimize capture
of solar energy early morning or late afternoon.
[0262] Also, the wings can be folded upwards for transportation
about hinge 419, or downwards relative to hull 409, to catch
afternoon rays of the sun, for example by tilting hull 409 on the
beach, or by heeling the hull in the water.
[0263] Because air propeller 415 could create problems for persons
not used to propeller driven vehicles, it is preferred, and
recommended by this writer, that aerodynamic propulsion should use
a shroud or duct. Small light electric motor 420 is powered by
batteries 421 mounted at a low position inside the hull, thus
avoiding need to have a transmission. A brushless motor is
preferred for greater efficiency and cool running temperature.
Light weight batteries such as nickel-metal hydride, or even
better, expensive ion-lithium batteries, would minimize vehicle
weight. High efficiency of battery and electric motor will be key
for light weight needed in a man powered craft, because it needs to
be carried, often by hand from shore to a car. Added cost provides
added safety, and with the propeller as in FIG. 42, there is no
obstacle to beaching the TH trimaran.
[0264] Moreover, unique added features are needed surrounding the
propeller's disc, to prevent accident. A safe alternative is the
use of a ducted propeller shown in FIG. 43, comprising duct 423
mounted on rear deck of hull 409, with an internal impeller 425 and
a frontal louver or mesh 426, to impede accidental insertion of a
hand, or air-driven rags. A similar mesh should be used on the
ducts rear mouth, which can also have an air rudder 428. The
external upper and side surfaces of the duct can also have solar
panels symbolized as 429, further increasing solar panel area.
[0265] The folding feature of the wings supporting the lateral
hulls is shown, by way of example, in FIG. 44, for the "proa" of
FIG. 38, with hand retracted position over and across the hull, and
hand driven deployment path 430 for deployed position of FIG. 38.
FIG. 45 shows half of the retracted position for the trimaran of
FIGS. 42 and 43, with deployment path 431. Similar retracting and
deployment methods can use electric or hydraulic acceleration,
specially for larger craft.
[0266] FIG. 46 shows a new type of stern planform for TH
configuration using a vee exit. The flow below the hull now has
different subcritical pattern shown in FIG. 47, comprising two
separate semi-gothic arch wake planforms 432 and 433 which occur at
different Froude numbers than for a rectilinear stern planform, as
has been established experimentally. The subcritical flow becomes a
single supercritical wake between rays 434 and 435 at a different
Froude number, compared to that for a supercritical regime of a
non-vee TH stern planform.
[0267] The numerical values of the design criteria mentioned above
are representative for the hull characteristics reviewed, and may
be adjusted for specific TH hull shapes with full size weights,
corresponding thrust line positions, and other design features
within the spirit of the invention and its claims.
[0268] The specifications and drawings pertain to hydrodynamics and
TH shapes and does not cover structural details of mechanisms, and
because model tests are not sufficient for determining stability of
full size manned TH of unknown weight, or other safety related
matter, these matters should be investigated and determined solely
by licensed manufacturers, who have the sole responsibility in such
matters.
[0269] Changes can be made on the drawings and specifications
without departing from the teachings as covered in the claims of
the invention.
* * * * *