U.S. patent application number 12/264890 was filed with the patent office on 2009-02-19 for flying object with tandem rotors.
This patent application is currently assigned to SILVERLIT TOYS MANUFACTORY, LTD.. Invention is credited to Kei Fung Choi, Alexander Jozef Magdalena Van de Rostyne.
Application Number | 20090047862 12/264890 |
Document ID | / |
Family ID | 36950880 |
Filed Date | 2009-02-19 |
United States Patent
Application |
20090047862 |
Kind Code |
A1 |
Van de Rostyne; Alexander Jozef
Magdalena ; et al. |
February 19, 2009 |
FLYING OBJECT WITH TANDEM ROTORS
Abstract
A flying object with tandem rotors, in particular a helicopter,
has a main rotor and a tandem rotor each with propeller blades
which are driven by a rotor shaft and which is hinge-mounted to
this rotor shaft. The angle between the surface of rotation of the
main rotor and the rotor shaft may vary. A swinging manner on an
oscillatory shaft is essentially transverse to the rotor shaft of
the main rotor and is directed transversally to the longitudinal
axis of the vanes. The main rotor and the tandem rotor each have an
auxiliary rotor connected respectively to the main rotor and tandem
rotor by a mechanical link. The swinging motions of the auxiliary
rotor controls the angle of incidence (A) of at least one of the
propeller blades of the main rotor and tandem rotor. There is an
acute angle of displacement when viewing the propeller blades
relative to the vanes in a direction perpendicular to their
respective rotational planes.
Inventors: |
Van de Rostyne; Alexander Jozef
Magdalena; (Bornem, BE) ; Choi; Kei Fung;
(Quarry Bay, HK) |
Correspondence
Address: |
GREENBERG TRAURIG LLP (LA)
2450 COLORADO AVENUE, SUITE 400E, INTELLECTUAL PROPERTY DEPARTMENT
SANTA MONICA
CA
90404
US
|
Assignee: |
SILVERLIT TOYS MANUFACTORY,
LTD.
Causeway Bay
HK
|
Family ID: |
36950880 |
Appl. No.: |
12/264890 |
Filed: |
November 4, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11736506 |
Apr 17, 2007 |
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12264890 |
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11462177 |
Aug 3, 2006 |
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11736506 |
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11465781 |
Aug 18, 2006 |
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11462177 |
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Current U.S.
Class: |
446/38 |
Current CPC
Class: |
B64C 27/43 20130101;
B64C 27/82 20130101; A63H 30/04 20130101; A63H 27/06 20130101; A63H
27/12 20130101 |
Class at
Publication: |
446/38 |
International
Class: |
A63H 27/133 20060101
A63H027/133 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 19, 2006 |
BE |
2006/0043 |
Claims
1. A remote control toy helicopter comprising: a body; a main rotor
with propeller blades driven by a first rotor shaft on which the
blades are mounted, and a main motor for rotating the main rotor; a
tandem rotor with propeller blades driven by a second rotor shaft
mounted at a distance relative to the first rotor shaft, and a
tandem motor for rotating the tandem rotor; an auxiliary rotor
driven by the first rotor shaft of the main rotor in the same sense
of rotation of the main rotor; the auxiliary rotor being mounted in
a swinging relationship on an oscillatory shaft and the swinging
motion being relatively upwardly and downwardly about the
oscillatory shaft, and which oscillatory shaft is provided
essentially transverse to the rotor shaft of the main rotor; the
main rotor and the auxiliary rotor being connected to each other by
a mechanical link, such that the swinging motion of the auxiliary
rotor controls the angle of incidence of at least one of the
propeller blades of the main rotor; the first rotor shaft and the
tandem rotor shaft being essentially upwardly directed and the
plane of rotation of the main rotor propeller blades and the tandem
rotor propeller blades being essentially to create upward lift; and
the diameter of the propeller blades of the main rotor and the
propeller blades of the tandem rotor being about equal; wherein the
main rotor and the tandem rotor rotate in the same direction; and a
battery for the main rotor and tandem rotor, and the main rotor and
the tandem rotor being controllable by a remote controller remote
from the body.
2. A helicopter as claimed in claim 1, wherein the body includes a
front end and the extent of the body at the front end is
substantially at the same position as the outer circumferential
position of the main rotor, and wherein the body includes a rear
end and the extent of the body at the rear end is substantially the
same position as the outer circumferential position of the tandem
rotor.
3. A helicopter as claimed in claim 1, wherein the body includes a
rear end and the extent of the body at the rear end is
substantially the same position as the outer circumferential
position of the tandem rotor.
4. A helicopter as claimed in claim 1, wherein at least one of the
first rotor shaft for the main rotor or the second rotor shaft for
the tandem rotor is relatively inclined in relation to a vertical
axis through the body, the inclination being opposite to each other
relative to the vertical axis, and including a linkage between the
first rotor shaft and the tandem rotor shaft and including a motor
for moving the linkage whereby the relative angle of the first
rotor shaft and the second rotor shaft is selectively variable
relative to the vertical axis.
5. A helicopter according to claim 1, wherein the auxiliary rotor
includes elongated members, the elongated members being for driven
for rotation with the first rotor, and wherein the elongated
members have a generally longitudinal axis located at an acute
angle relative to a generally longitudinal axis of one of the
respective propeller blades of the main rotor, and wherein each
propeller blade has a profile wherein along the direction of its
generally longitudinal axis of each propeller blade there is a
first longitudinal convex curve from a position towards the first
rotor shaft to a position towards an end area of the blade.
6. A helicopter according to claim 1, including an auxiliary rotor
driven by the second rotor shaft of the tandem rotor in the sense
of rotation of the tandem rotor, the auxiliary rotor of the tandem
rotor being mounted in a swinging relationship on an oscillatory
shaft and the swinging motion being relatively upwardly and
downwardly about the oscillatory shaft, and which oscillatory shaft
is provided essentially transverse to the rotor shaft of the tandem
rotor, the tandem rotor and the auxiliary rotor being connected to
each other by a mechanical link, such that the swinging motion of
the auxiliary rotor controls the angle of incidence of at least one
of the propeller blades of the tandem rotor.
7. A helicopter according to claim 1, wherein the main rotor and
tandem rotor each include two propeller blades, the blades of each
rotor being situated essentially in line with each other, and the
two blades for each rotor being elongated, and wherein each
propeller blade includes a transverse convex curve in a profile on
its top face from a position towards a leading edge towards a
position towards a trailing edge, and a transverse convex curve
preferably being present over a substantial generally longitudinal
length of the blade.
8. A helicopter according to claim 7, wherein each propeller blade
includes a transverse concave curve in a profile on its bottom face
from a position towards a leading edge towards a position towards a
trailing edge, and the transverse convex curve preferably being
present over a substantial generally longitudinal length of the
blade.
9. A helicopter as claimed in claim 1, wherein at least one of the
rotor shaft for the main rotor or the rotor shaft for the tandem
rotor is relatively inclined in relation to a vertical axis through
the body, and including a motor for changing the axis of the first
rotor shaft or the second rotor shaft, whereby the relative angle
of the first rotor shaft or the second rotor shaft is selectively
variable relative to the vertical axis.
10. A helicopter as claimed in claim 1, wherein the first shaft and
the second shaft are relatively inclined to the vertical axis
through the body, and wherein the inclination of the first rotor
shaft and the second rotor shaft are oppositely inclined relative
to the vertical axis and including a motor for changing the axis of
the first rotor shaft or the second rotor shaft, whereby the
relative angle of the first rotor shaft or the second rotor shaft
is selectively variable relative to the vertical axis.
11. A remote control toy helicopter comprising: a body; a main
rotor with propeller blades which is driven by a first rotor shaft
and which is mounted on the first rotor shaft, and a main motor for
rotating the main rotor; a first auxiliary rotor operable with the
main rotor, the auxiliary rotor being provided with two elongated
members, the motion of the first auxiliary rotor controlling the
angle of incidence of at least one of the propeller blades of the
main rotor; a tandem rotor with propeller blades driven by a second
rotor shaft mounted at a distance relative to the rotor shaft of
the main rotor, and a tandem motor for rotating the tandem rotor; a
second auxiliary rotor with the tandem rotor, and the second
auxiliary rotor being provided with two elongated members, the
motion of the second auxiliary rotor controlling the angle of
incidence of at least one of the propeller blades of the tandem
rotor; wherein the body or an extension of the body extends
substantially to the circumferential end of the main rotor and the
circumferential end of tandem rotor; and a battery for the main
rotor and tandem rotor, and the main rotor and the tandem rotor
being controllable by a remote controller remote from the body
12. A helicopter according to claim 11, wherein the main rotor and
the tandem rotor rotate in the same direction.
13. A helicopter according to claim 11, wherein the first and
second auxiliary rotors are mounted such that the longitudinal axis
of one of the propeller blades of the main rotor and tandem rotor
is located relative to the longitudinal axis of the respective
elongated members of the first and second auxiliary rotors, such
that the acute angle between the plane of rotation of the main
rotor and the first rotor shaft and the tandem rotor and the second
rotor shaft is variable; and wherein the longitudinal axis of one
of the propeller blades of the main rotor and tandem rotor is
located at an acute angle relative to the longitudinal axis of a
respective elongated member of the first and second auxiliary
rotor, and wherein the main rotor and the tandem rotor rotate in
the same direction.
14. A helicopter according to claim 11, wherein the auxiliary
rotors respectively include elongated members, the elongated
members being for driven for rotation with the first rotor, and
wherein the elongated members have a generally longitudinal axis
located at an acute angle relative to a generally longitudinal axis
of one of the respective propeller blades of the main rotor and
tandem rotor, and wherein each propeller blade has a profile
wherein along the direction of its generally longitudinal axis of
each propeller blade there is a first longitudinal convex curve
from a position towards the first rotor shaft to a position towards
an end area of the blade and wherein the main rotor and the tandem
rotor rotate in the same direction.
15. A helicopter according to claim 11, wherein the main rotor and
tandem rotor each include two propeller blades, the blades of each
rotor being situated essentially in line with each other, and the
two blades for each rotor being elongated, and wherein each
propeller blade includes a transverse convex curve in a profile on
its top face from a position towards a leading edge towards a
position towards a trailing edge, and the transverse convex curve
preferably being present over a substantial generally longitudinal
length of the blade and wherein the main rotor and the tandem rotor
rotate in the same direction.
16. A helicopter as claimed in claim 11, wherein at least one of
the first rotor shaft for the main rotor or the second rotor shaft
for the tandem rotor is relatively inclined in relation to a
vertical axis through the body.
17. A helicopter as claimed in claim 11, wherein the first shaft
and the second shaft are relatively inclined to the vertical axis
through the body, and wherein the inclination of the first rotor
shaft and the second rotor shaft are oppositely inclined relative
to the vertical axis, and including a motor for changing the axis
of the first rotor shaft or the second rotor shaft, whereby the
relative angle of the first rotor shaft or the second rotor shaft
is selectively variable relative to the vertical axis.
18. A remote control toy helicopter comprising: a body; a main
rotor with propeller blades which is driven by a first rotor shaft
and which is mounted on the first rotor shaft, and a main motor for
rotating the main rotor; a first auxiliary rotor operable with the
main rotor, the auxiliary rotor being provided with two elongated
members, the motion of the first auxiliary rotor controlling the
angle of incidence of at least one of the propeller blades of the
main rotor; a tandem rotor with propeller blades driven by a second
rotor shaft mounted at a distance relative to the rotor shaft of
the main rotor, and a tandem motor for rotating the tandem rotor; a
second auxiliary rotor with the tandem rotor, and the second
auxiliary rotor being provided with two elongated members, the
motion of the second auxiliary rotor controlling the angle of
incidence of at least one of the propeller blades of the tandem
rotor; wherein the body or an extension of the body extends
substantially to the circumferential end of the main rotor and the
circumferential end of tandem rotor, a battery for the main rotor
and tandem rotor, and the main rotor and the tandem rotor being
controllable by a remote controller remote from the body; and
wherein the first shaft and the second shaft are relatively
inclined to the vertical axis through the body, and wherein the
inclination of the first rotor shaft and the second rotor shaft are
oppositely inclined relative to the vertical axis, and including a
third motor for changing the axis of the first rotor shaft or the
second rotor shaft, whereby the relative angle of the first rotor
shaft or the second rotor shaft is selectively variable relative to
the vertical axis, and wherein the third motor is located
relatively closer to either the first rotor shaft or the second
rotor shaft.
Description
RELATED APPLICATIONS
[0001] This application is a Continuation of U.S. Utility patent
application Ser. No. 11/736,506 filed on Apr. 17, 2007, which in
turn is a Continuation-in-Part of both U.S. Utility patent
application Ser. No. 11/462,177 filed on Aug. 3, 2006 and U.S.
Utility patent application Ser. No. 11/465,781 filed on Aug. 18,
2006, all of which claim priority to Belgian Patent Application No.
2006/0043 filed on Jan. 19, 2006. The contents of these
applications are incorporated by reference herein.
BACKGROUND
[0002] The present disclosure concerns an improved flying object
with tandem rotors, in particular a helicopter.
[0003] The disclosure concerns a helicopter generally. In
particular, but not exclusively, it is related to a toy helicopter
and in particular to a remote-controlled model helicopter or a toy
helicopter.
[0004] A helicopter is a complex machine, which is generally
unstable and as a result difficult to control. Significant
experience is required to safely operate helicopters without
mishaps.
[0005] Typically, a helicopter includes a body, a main rotor and a
tail rotor. In other cases a helicopter includes a body, a main
rotor and a second tandem rotor. The disclosure is concerned
primarily with a helicopter having a main rotor and a tandem
rotor.
[0006] Tandem helicopters have two rotors of more or less similar
diameter. The rotors are disposed along the helicopter body
typically towards each end. The tips of the rotor paths may overlap
to a certain extend. In that case one rotor is positioned higher
than the other to avoid collision of the rotor blades.
[0007] It has been shown that the counter rotation of rotors on a
tandem configuration, where the rotor axes are at a certain
distance from each other, have destabilizing and asymmetrical
effects. Yaw changes induce fore/aft drift, and the rotors push the
tandem to lean over and slip. Different lift forces are required
for example to move the helicopter forward or backward, and thereby
different torques between the two rotors create undesired yaw
effects. The combination of all these effects makes it hard to find
a natural trim of the tandem for stable hover without pilot
correction on the fore/aft and sideways dimension.
[0008] The main rotor and tandem rotor provide an upward force to
keep the helicopter in the air, as well as a lateral or forward or
backward force to steer the helicopter in required directions. This
can be achieved by making the angle of incidence of the propeller
blades of the rotors vary cyclically with revolutions of the
rotors.
[0009] The rotors have a natural tendency to deviate from its
position, which may lead to uncontrolled movements and to a crash
of the helicopter if the pilot loses control over the steering of
the helicopter.
[0010] Solutions make use of the known phenomenon of gyroscopic
precession caused by the Coreolis force and the centrifugal forces
to obtain the desired effect.
[0011] In general, the stability of a tandem helicopter includes
the result of the interaction between:
[0012] the rotation of the rotor blades; the movements of any
possible stabilizing rods;
[0013] the system, such as a gyroscope or the like, to compensate
for small undesired variations in the resistance torque of the
rotors; and
[0014] control of the helicopter, which controls the rotors.
[0015] When these elements are essentially in balance, the pilot
should be able to steer the helicopter as desired.
[0016] This does not mean, however, that the helicopter can fly by
itself or on auto pilot and can thus maintain a certain flight
position or maneuver, for example, hovering or making slow
movements without the intervention of a pilot.
[0017] Moreover, flying a helicopter usually requires intensive
training and much experience of the pilot, for both a full size
operational real helicopter as well as a toy helicopter or a
remote-controlled model helicopter.
SUMMARY
[0018] The present disclosure aims to minimize one or several of
the above-mentioned and other disadvantages by providing a simple
and cheap solution to auto stabilize a flying object with tandem
rotors, in particular a helicopter. Operating the helicopter
becomes simpler and possibly reduces the need for long-standing
experience of the pilot.
[0019] The flying object with tandem rotors, in particular a
helicopter, should meet the following requirements to a greater or
lesser degree:
[0020] (a) it can return to a stable hovering position, in case of
an unwanted disturbance of the flight conditions. Such disturbance
may occur in the form of a gust of wind, turbulences, a mechanical
load change of the body or the rotors, a change of position of the
body as a result of an adjustment to the cyclic variation of the
pitch or angle of incidence of the propeller blades of the rotors;
and
[0021] (b) the time required to return to the stable position
should be relatively short and the movement of the helicopter
should be relatively small.
[0022] The disclosure concerns a flying object with tandem rotors,
in particular a helicopter, including a body with a main rotor with
propeller blades which are driven by a rotor shaft and which are
mounted to the rotor shaft by a joint. The angle between the
surface of rotation of the main rotor and the rotor shaft may vary.
There is also a tandem rotor which has propeller blades which are
driven by a rotor shaft and which are mounted to the rotor shaft by
a joint. The angle between the surface of rotation of the tandem
rotor and the rotor shaft may vary.
[0023] The helicopter includes the autostable rotors as described
in U.S. patent application Ser. No. 11/462,177, filed on Aug. 3,
2006 and entitled HELICOPTER, and No. 11/465,1781, filed on Aug.
18, 2006 entitled HELICOPTER.
[0024] In one form of the disclosure, the helicopter has both the
main rotor and the tandem rotors spinning in the same direction. In
another form of the disclosure, the helicopter has the main rotor
and the tandem rotors spinning in opposite directions.
[0025] When an external yaw disturbance causes the body to rotate,
then both rotors see the same amount of decrease or increase in
rotation speed for rotors rotating in the same direction. When the
rotors are counter-rotating, the amount is similar but the changes
are opposite. This is about equal to the rotation speed of the
body.
[0026] The two rotors, namely the main rotor and the tandem rotor,
are located at a certain horizontal distance one from another.
Those rotors are inclined in the case of same direction turning
rotor, such that they essentially compensate for the torque effects
induced by the spinning rotors.
[0027] The effects of yaw, pilot induced or uninitiated/unwanted,
essentially overcomes drift in the for/after dimension, and
undesired inclination of the body. The spiral thrust essentially
does not incline or cause sideways drift the body when rotors turn
in same direction.
[0028] In one form of the disclosure, the helicopter main and
tandem rotors are each provided with an auxiliary rotor which is
driven by the shaft of the respective main rotor or tandem rotor.
The auxiliary rotor is provided with two vanes extending
essentially in line or at an acute angle relative with their
longitudinal axes. This acute angle of displacement is determined
when viewing the propeller blades relative to the vanes in a
direction perpendicular to their respective rotational planes.
[0029] In some other forms of the disclosure, there may be an
auxiliary rotor on only one of the main rotor or the tandem
rotor.
[0030] The `longitudinal` axis is seen in the plane of rotation of
the main rotor, and is essentially parallel to the longitudinal
axis of at least one of the propeller blades of the main rotor or
is located at a relatively small acute angle with the latter
propeller blade axis. As such each vane of the auxiliary rotor is
relatively offset from the respective propeller of the main rotor
when viewed perpendicular to the plane of rotation of the main
rotor and the auxiliary rotor.
[0031] This auxiliary rotor is provided in a swinging manner on an
oscillatory shaft which is provided essentially transversal to the
rotor shaft of the main and tandem rotor respectively. This is
directed essentially transverse to the longitudinal axis of the
vanes.
[0032] The main rotor and the auxiliary rotor are connected to each
other through a mechanical link, such that the swinging motions of
the auxiliary rotor control the angle of incidence of at least one
of the propeller blades of the main rotor. The tandem rotor and the
auxiliary rotor are connected to each other through a mechanical
link, such that the swinging motions of the auxiliary rotor control
the angle of incidence of at least one of the propeller blades of
the main rotor.
[0033] In some cases, the yaw control of the tandem helicopter is
enhanced by extending the body forwardly and/or rearwardly by using
a fin extension and/or extending the body itself in at least one of
those directions. Having both the front and the rear extended is an
effective yaw control.
[0034] In practice, it appears that such an improved tandem
helicopter is more stable and stabilizes itself relatively quickly
with or without a restricted intervention of the user.
[0035] The main rotor with propeller blades is driven by a rotor
shaft on which the blades are mounted. The auxiliary rotor is
driven by the rotor shaft of the main rotor and is provided with
vanes from the rotor shaft in the sense of rotation of the main
rotor.
[0036] The auxiliary rotor is mounted in a swinging relationship on
an oscillatory shaft and the swinging motion being relatively
upwardly and downwardly about the auxiliary shaft. The auxiliary
shaft is provided essentially transverse to the rotor shaft of the
main rotor. The main rotor and the auxiliary rotor are connected to
each other by a mechanical link, such that the swinging motion of
the auxiliary rotor controls the angle of incidence of at least one
of the propeller blades of the main rotor.
[0037] The angle of incidence of the rotor in the plane of rotation
of the rotor and the rotor shaft may vary; and an auxiliary rotor
rotatable with the rotor shaft is for relative oscillating movement
about the rotor shaft. Different relative positions are such that
the auxiliary rotor causes the angle of incidence the main rotor to
be different. A linkage between the main and auxiliary rotor causes
changes in the position of the auxiliary rotor to translate to
changes in the angle of incidence.
[0038] The propeller blades of the main rotor and the vanes of the
auxiliary rotor respectively are connected to each other with a
mechanical linkage that permits the relative movement between the
blades of the propeller and the vanes of the auxiliary rotor.
DRAWINGS
[0039] In order to further explain the characteristics of the
disclosure, the following embodiments of an improved helicopter
according to the disclosure are given as an example only, without
being limitative in any way, with reference to the accompanying
drawings, in which:
[0040] FIG. 1 represents a perspective view of an embodiment of the
helicopter with the rotors turning in the same direction;
[0041] FIG. 2 represents a top view of the embodiment of the
helicopter with the rotors turning in the same direction;
[0042] FIG. 3 represents a bottom view of the embodiment of the
helicopter with the rotors turning in the same direction;
[0043] FIG. 4 represents a front view of the embodiment of the
helicopter with the rotors turning in the same direction;
[0044] FIG. 5 is a rear view of the embodiment of the helicopter
with the rotors turning in the same direction;
[0045] FIG. 6 is a right view of the embodiment of the helicopter
with the rotors turning in the same direction;
[0046] FIG. 7 is a left view of the embodiment of the helicopter
with the rotors turning in the same direction;
[0047] FIG. 8 is a sectional side view of the embodiment of the
helicopter with the rotors turning in the same direction;
[0048] FIG. 9 is a sectional front view through the front rotor
structure of the helicopter with the rotors turning in the same
direction.
[0049] FIG. 10 represents another configuration of a tandem
helicopter as viewed from the side with the rotors turning opposite
to each other;
[0050] FIG. 11 represents another configuration of a tandem
helicopter as viewed from the top with the rotors turning opposite
to each other;
[0051] FIG. 12 represents a typical diagrammatic configuration of a
tandem helicopter as viewed from the top with the rotors turning
opposite to each other;
[0052] FIG. 13 represents a typical diagrammatic configuration of a
tandem helicopter as viewed from the side with the rotors turning
opposite to each other with the stabilizer removed for clarity;
[0053] FIG. 14 represents a typical diagrammatic configuration of a
tandem helicopter as viewed from the top with the rotors turning in
the opposite direction, with the stabilizer omitted for
clarity;
[0054] FIG. 15 represents a typical diagrammatic configuration of a
tandem helicopter as viewed from the front with the rotors turning
in the opposite direction, with the stabilizer omitted for
clarity;
[0055] FIG. 16 represents a typical diagrammatic configuration of a
tandem helicopter as viewed from the top with the rotors turning in
the same direction;
[0056] FIG. 17 represents a typical diagrammatic configuration of a
tandem helicopter as viewed from the front with the rotors turning
in the same direction, with the stabilizer omitted for clarity;
[0057] FIG. 18 represents another configuration of a tandem
helicopter as viewed from the side;
[0058] FIG. 19 represents another configuration of a tandem
helicopter as viewed from the side, with the stabilizer omitted for
clarity with the rotors turning in the same direction;
[0059] FIG. 20 represents a configuration of a tandem helicopter of
FIG. 19 as viewed from the top, with the stabilizer omitted for
clarity with the rotors turning in the same direction;
[0060] FIG. 21 represents a configuration of a tandem helicopter of
FIG. 19 as viewed from the top, with the stabilizer omitted for
clarity with the rotors turning in the same direction;
[0061] FIG. 22 represents another configuration of a tandem
helicopter as viewed from the side, with the stabilizer omitted for
clarity with the rotors turning in the same direction;
[0062] FIG. 23 represents another configuration of a tandem
helicopter as viewed from a perspective side position, with the
rotors and stabilizer omitted for clarity with the rotors turning
in the same direction;
[0063] FIG. 24A represents the configuration of a tandem helicopter
of FIG. 23 as viewed from the front, with the rotors and stabilizer
omitted for clarity with the rotors turning in the same
direction;
[0064] FIG. 24B represents the configuration of a tandem helicopter
of FIG. 23 as viewed from the rear, with the rotors and stabilizer
omitted for clarity with the rotors turning in the same
direction;
[0065] FIG. 25 represents yet another configuration of a tandem
helicopter as viewed in perspective with the rotors and stabilizer
omitted for clarity with the rotors turning in the same
direction;
[0066] FIG. 26 represents the system for controlling yaw in a
tandem helicopter with the rotors turning in the same
direction;
[0067] FIG. 27 represents a detail of the main rotor and auxiliary
rotor;
[0068] FIG. 28 is a further representation of the main rotor and
auxiliary rotor;
[0069] FIG. 29 is a further detailed representation of the main
rotor and auxiliary rotor and linkages between them; and
[0070] FIG. 30 is a further detailed representation of the main
rotor and auxiliary rotor.
DETAILED DESCRIPTION
[0071] A helicopter comprises a body, a main rotor with propeller
blades which is driven by a rotor shaft on which the blades are
mounted. There is a tandem rotor driven by a second rotor shaft. In
some cases the rotor shafts are directed substantially parallel to
the rotor shaft of the main rotor. In other cases, the rotor shafts
can be inclined relative to each other. One shaft can incline to
the left, and the other shaft can incline to the right as viewed
from the front or the rear of the helicopter or vice versa.
[0072] An auxiliary rotor is driven by the rotor shaft of the main
rotor and is provided with vanes from the rotor shaft for rotation
in the sense of rotation of the main rotor. The auxiliary rotor is
mounted in a swinging relationship on an oscillatory shaft and the
swinging motion is relatively upwardly and downwardly about the
auxiliary shaft.
[0073] The diameter of the auxiliary rotor is smaller than the
diameter of the main rotor. The main rotor and the tandem rotor
rotate in the same direction.
[0074] The auxiliary shaft for the main rotor is provided
essentially transverse to the rotor shaft of the main rotor. The
main rotor and the auxiliary rotor are connected to each other by a
mechanical link, such that the swinging motion of the auxiliary
rotor controls the angle of incidence of at least one of the
propeller blades of the main rotor.
[0075] There is also an auxiliary rotor driven by the rotor shaft
of the tandem rotor. There are vanes from the tandem rotor shaft
for rotation in the sense of rotation of the tandem rotor. The
auxiliary rotor is mounted in a swinging relationship on an
oscillatory shaft and the swinging motion being relatively upwardly
and downwardly about the auxiliary shaft. There are configurations
where only one of the two rotor is equipped with an auxiliary
rotor.
[0076] The auxiliary shaft for the tandem rotor is provided
essentially transverse to the rotor shaft of the tandem rotor. The
tandem rotor and the auxiliary rotor are connected to each other by
a mechanical link, such that the swinging motion of the auxiliary
rotor controls the angle of incidence of at least one of the
propeller blades of the tandem rotor
[0077] The main rotor and tandem rotor each includes two propeller
blades situated essentially in line with each other in some cases.
In other cases, the rotor shafts are inclined relative to each
other.
[0078] The propeller blades of the main rotor, and the vanes of the
auxiliary rotor are connected to the main rotor with a mechanical
linkage that permits the relative movement between the blades of
the main propeller and the vanes of the auxiliary rotor. There is a
joint of the main rotor to the propeller blades formed of a
spindle, which is fixed to the rotor shaft of the main rotor.
[0079] The propeller blades of the tandem rotor, and the vanes of
the auxiliary rotor for the tandem rotor are connected to the
tandem rotor with a mechanical linkage that permits the relative
movement between the blades of the tandem propeller and the vanes
of the auxiliary rotor. There is a joint of the tandem rotor to the
propeller blades formed of a spindle, which is fixed to the rotor
shaft of the tandem rotor.
[0080] The spindle of the main rotor and tandem rotors extend
essentially in the longitudinal direction of the propeller blade of
the main rotor and tandem rotors respectively. This is parallel to
one of the vanes or is located at an acute angle relative to the
longitudinal direction.
[0081] The mechanical link includes a rod hinge mounted to a vane
of the auxiliary rotor with one fastening point and is
hinge-mounted with another fastening point to the propeller blade
of the main rotor. The fastening point of the rod is situated on
the main rotor at a distance from the axis of the spindle of the
propeller blades of the main rotor, and the other fastening point
of the rod is situated on the auxiliary rotor at a distance from
the axis of the oscillatory shaft of the auxiliary rotor. The rod
is fixed to lever arms with its fastening point respectively part
of the main rotor and of the auxiliary rotor A similar construction
applies between the propeller blade of the tandem rotor and the
vanes of the auxiliary rotor of the tandem rotor
[0082] The distance between the fastening point of the rod on the
main rotor and the axis of the spindle of the propeller blades of
the main rotor is larger than the distance between the fastening
point of the rod on the auxiliary rotor and the axis of the
oscillatory shaft of the auxiliary rotor. A similar construction
and configuration applies for the propeller blade of the tandem
rotor and the vanes of the auxiliary rotor of the tandem rotor
[0083] The longitudinal axis of the vanes of the auxiliary rotor in
the plane of rotation is located at an acute angle relative to each
other. This angle can be about 10.degree. to about 17.degree. with
the longitudinal axis of one of the propeller blades of the main
rotor. In another form, the longitudinal axis of one of the
propeller blades of the main rotor in the plane of rotation, is
located at an acute angle with the axis of a spindle mounting these
propeller blades to the rotor shaft.
[0084] The `longitudinal` axis is seen in the plane of rotation of
the main rotor, and is essentially parallel to the longitudinal
axis of at least one of the propeller blades of the main rotor or
is located at a relatively small acute angle with the latter
propeller blade axis. Each vane of the auxiliary rotor is
relatively offset from the respective propeller of the main rotor
that is closest to it.
[0085] When viewed perpendicular to the plane of rotation of the
main rotor and the auxiliary rotor this offset is a small acute
angle. In some case each vane and its respective closest or related
propeller are aligned and not offset. The vanes can be of any size
and shape. The vanes can have a shape as a blade. In some
situations there can be a rod which is at a relatively small angle,
for instance about 17 degrees relative to the propeller. The blades
of the vanes can have any suitable profile as viewed from an end, a
cross-section laterally through the vane or longitudinally through
the vane or longitudinally from a side. In some cases the rods are
cylindrical elements and may have weights disposed at different
points on the rods.
[0086] In a different manner, there is provided a helicopter having
a body; and a main rotor with propeller blades which is driven by a
rotor shaft and which is mounted on this rotor shaft. The system
permits the angle of incidence of the main rotor in the plane of
rotation of the rotor and the rotor shaft to vary. An auxiliary
rotor is rotatable with the rotor shaft and is for relative
oscillating movement about the rotor shaft. Different relative
positions are established so that the auxiliary rotor causes the
angle of incidence the main rotor to be different.
[0087] In yet a different manner, a helicopter has a body; and a
main rotor with propeller blades which is driven by a rotor shaft
and which is mounted on this rotor shaft. The angle between the
plane of rotation of the main rotor and the rotor shaft may vary.
An auxiliary rotor is driven by the rotor shaft of the main rotor
and is provided with two vanes. The main rotor and the auxiliary
rotor are connected to each other by a mechanical link, such that
the motion of the auxiliary rotor controls the angle of incidence
of at least one of the propeller blades of the main rotor. There is
a tandem rotor which is driven by a second rotor shaft which is
directed substantially parallel to the rotor shaft of the main
rotor.
[0088] The helicopter can be such the main rotor and the tandem
rotor rotate in the same direction. Alternatively the main rotor
and the tandem rotor rotate in the opposite.
[0089] The helicopter 1 represented in the figures generally by way
of example is a remote-controlled helicopter which essentially
includes a body 2 which can include some form of a landing gear.
There is a first system 4 being a main rotor 4a; an auxiliary rotor
5a driven synchronously, and also a second system 5 being a tandem
rotor 4b; an auxiliary rotor 5b driven synchronously. The auxiliary
rotors 5a and 5b and related controls, being the drive and/or
control rods from respectively two stabilizers for the
helicopter.
[0090] The main rotor 4a is provided by a rotor head 7a on a first
upward directed rotor shaft 8a which is bearing-mounted in the body
2 of the helicopter 1 in a rotating manner. This is driven by a
motor 9a and a transmission 10a, including gearing. The motor 9a is
for example an electric motor which is powered by an electric
microprocessor and battery 11. The tandem rotor system is similarly
constructed, namely there is a motor 9b and a transmission 10b,
whereby the motor 9b is for example an electric motor which is
powered by a battery 11.
[0091] The main rotor 4a in this case has two propeller blades 12a
which are in line or practically in line, but which may just as
well be composed of a larger number of propeller blades 12a. The
tandem rotor 4b in this case has two propeller blades 12b which are
in line or practically in line, but which may just as well be
composed of a larger number of propeller blades 12b.
[0092] The tilt or angle of incidence A, as shown in detail in FIG.
27, of the propeller blades 12a, in other words the angle A which
forms the propeller blades 12a as represented with the plane of
rotation 14 of the main rotor 4a, can be adjusted as, the main
rotor 4a is hinge-mounted on this rotor shaft 8a by means of a
joint, such that the angle between the plane of rotation of the
main rotor and the rotor shaft may freely vary. A similar, but not
necessarily identical, configuration and operation is provided for
the tandem rotor system. For instance, the tandem rotor may be more
or less more or less weight in the auxiliary rotor, or a different
size or shape relative to the main rotor system.
[0093] In the case of the example of a main rotor 4a with two
propeller blades 12a, the joint is formed by a spindle 15a of the
rotor head 7a. A similar configuration and operation is provided
for the tandem rotor system with regard to rotors 4b and 5b, and
blades 12b.
[0094] The axis 14a of the auxiliary rotor 5a preferably forms an
acute angle B with the longitudinal axis 13a of the rotor 4a. A
similar configuration and operation is provided for the tandem
rotor system with regard to rotors 4b and 5b and blades 12b. There
is a similar relationship with axis 13b and 14b.
[0095] The helicopter 1 is also provided with an auxiliary rotor 5a
which is driven substantially synchronously with the main rotor 4a
by the same rotor shaft 8a and the rotor head 7a. A similar
configuration and operation is provided for the tandem rotor system
with regard to rotors 4b and 5b.
[0096] The auxiliary rotor 5a in this case has two vanes which are
essentially in line with their longitudinal axis 14a. The
longitudinal axis 14a, seen in the sense of rotation R of the main
rotor 4a, is essentially parallel to the longitudinal axis 13a of
propeller blades 12 of the main rotor 4a or encloses a relatively
small acute angle B with the latter. Both rotors 4a and 5a extend
more or less parallel on top of one another with their propeller
blades 12 and vanes 5a. A similar configuration and operation is
provided for the tandem rotor system with regard to rotors 4b and
5b. In FIG. 2 the angle is between axis 14a and the hinging line of
rotor 13 going through the spindle 15. The hinging line, not
represented, is parallel to the longitudinal axis, but may be
varied to alter or tune the stability system. In the case
represented the angles B and F are about the same so that the angle
G is about Zero degrees.
[0097] The diameter of the auxiliary rotor 5a is preferably smaller
than the diameter of the main rotor 4a as the vanes 5a have a
smaller span than the propeller blades 12, and the vanes 5a are
substantially rigidly connected to each other. This rigid whole
forming the auxiliary rotor 5a is provided in a swinging manner on
an oscillating shaft 30 which is fixed to the rotor head 7a of the
rotor shaft 8a. This is directed transversally to the longitudinal
axis of the vanes 12 and transversally to the rotor shaft 8a. A
similar configuration and operation is provided for the tandem
rotor system with regard to rotors 4b and 5b.
[0098] The main rotor 4a and the auxiliary rotor 5a are connected
to each other by a mechanical link such that the angle of incidence
A of at least one of the propeller blades 12 of the main rotor 4a
is set. In the given example this link is formed of a rod 31. A
similar configuration and operation is provided for the tandem
rotor system with regard to rotors 4b and 5b.
[0099] This rod 31 is hinge-mounted to a propeller blade 12 of the
main rotor 4a with one fastening point 32 by means of a joint 33
and a lever arm 34 and with another second fastening point 35
situated at a distance from the latter, it is hinge-mounted to a
vane of the auxiliary rotor 5a by means of a second joint 36 and a
second lever arm 37. A similar configuration and operation is
provided for the tandem rotor system with regard to rotors 4b and
5b.
[0100] The fastening point 32 on the main rotor 4a is situated at a
distance D from the axis 16 of the spindle 15 of the propeller
blades 12a of the main rotor 4a, whereas the other fastening point
35 on the auxiliary rotor 5a is situated at a distance E from the
axis 38 of the oscillatory shaft 30 of the auxiliary rotor 5a. A
similar configuration and operation is provided for the tandem
rotor system with regard to rotors 4b and 5b.
[0101] The distance D is preferably larger than the distance E.
Distance E is represented in FIGS. 2, 29 and 30 and the distance
between the axis of oscillatory shaft 30 and the axis of lever arm
37. Distance D is about double the distance of E. Both fastening
points 32 and 35 of the rod 31 are situated. This is in the sense
of rotation R on the same side of the propeller blades 12a of the
main rotor 4a or of the vanes 28 of the auxiliary rotor 5a. In
other words they are both situated in front of or at the back of
the propeller blades 12a and vanes 5a, as seen in the sense of
rotation. A similar configuration and operation is provided for the
tandem rotor system with regard to rotors 4b and 5b.
[0102] Also preferably, the longitudinal axis 14a of the vanes 5a
of the auxiliary rotor 5a, seen in the sense of rotation R,
encloses an angle B with the longitudinal axis 13a of the propeller
blades 12a of the main rotor 4a, which enclosed angle B is in the
order, of magnitude of about 10.degree. to about 17.degree.,
whereby the longitudinal axis 14a of the vanes 5a leads the
longitudinal axis 13a of the propeller blades 12a, seen in the
sense of rotation R. Different angles in a range of, for example,
5.degree. to 25.degree. could also be in order. A similar
configuration and operation is provided for the tandem rotor system
with regard to rotors 4b and 5b.
[0103] The auxiliary rotor 5a is provided with two stabilizing
weights 39 which are each fixed to a vane 5a at a distance from the
rotor shaft 8. A similar configuration and operation is provided
for the tandem rotor system with regard to rotors 4b and 5b.
[0104] Further, the helicopter 1 is provided with a receiver, so
that it can be controlled from a distance by means of a remote
control, which is not represented. A similar configuration and
operation is provided for the tandem rotor system with regard to
rotors 4b and 5b.
[0105] As a function of the type of helicopter, it is possible to
search for the most appropriate values and relations of the angles
B by experiment; the relation between the distances D and E and G
and F which are described below; the size of the weights 39 and the
relation of the diameters between the main rotor 4a and the
auxiliary rotor 5a so as to guarantee a maximum auto stability. A
similar configuration and operation is provided for the tandem
rotor system with regard to rotors 4b and 5b.
[0106] The operation of the improved helicopter 1 according to the
disclosure is as follows:
[0107] In flight, the rotors 4a and 5a are driven at a certain
speed, as a result of which a relative air stream is created in
relation to the rotors, as a result of which the main rotors 4a and
5a generate an upward force so as to make the helicopter 1 rise or
descend or maintain it at a certain height, and the rotors develop
a laterally directed force which is used to steer the helicopter 1.
A similar configuration and operation is provided for the tandem
rotor system with regard to rotors 4b and 5b.
[0108] It is impossible for the main rotor 4a to adjust itself, and
it will turn in the plane 114a in which it has been started,
usually the plane perpendicular to the rotor shaft 8a. Under the
influence of gyroscopic precession, turbulence and other factors,
it will take up an arbitrary undesired position if it is not
controlled. A similar configuration and operation is provided for
the tandem rotor system with regard to rotors 4b and 5b.
[0109] The surface of rotation of the auxiliary rotor 5a may take
up another inclination in relation to the surface of rotation 114a
of the main rotor 4a, whereby both rotors 5a and 4a may take up
another inclination in relation to the rotorshaft 8a.
[0110] This difference in inclination may originate in any internal
or external force or disturbance whatsoever.
[0111] In a situation whereby the helicopter 1 is hovering stable,
on a spot in the air without any disturbing internal or external
forces, the auxiliary rotor 5a keeps turning in a plane which is
essentially perpendicular to the rotor shaft 8a.
[0112] If, however, the body 2 is pushed out of balance due to any
disturbance whatsoever, and the rotor shaft 8 turns away from its
position of equilibrium, the auxiliary rotor 5a does not
immediately follow this movement, since the auxiliary rotor 5a can
freely move round the oscillatory shaft 30.
[0113] The main rotor 4a and the auxiliary rotor 5a are placed in
relation to each other in such a manner that a swinging motion of
the auxiliary rotor 5a is translated almost immediately in the
pitch or angle of incidence A of the propeller blades 12 being
adjusted. A similar configuration and operation is provided for the
tandem rotor system with regard to rotors 4b and 5b.
[0114] For a two-bladed main rotor 4a, this means that the
propeller blades 12 and the vanes 28 of both rotors 4a and 5a must
be essentially parallel or, seen in the sense of rotation R,
enclose an acute angle with one another of for example 10.degree.
to 17.degree. in the case of a large main rotor 4a and a smaller
auxiliary rotor 5a. A similar configuration and operation is
provided for the tandem rotor system with regard to rotors 4b and
5b.
[0115] This angle can be calculated or determined by experiment for
any helicopter 1 or per type of helicopter, and this angle can be
different for the rotor and the tandem rotor.
[0116] If the axis of rotation 8a takes up another inclination than
the one which corresponds to the above-mentioned position of
equilibrium in a situation whereby the helicopter 1 is hovering,
the following happens: A similar configuration and operation is
provided for the tandem rotor system with regard to rotors 4b and
5b.
[0117] A first effect is that the auxiliary rotor 5a will first try
to preserve its absolute inclination, as a result of which the
relative inclination of the surface of rotation of the auxiliary
rotor 5a in relation to the rotor shaft 8a changes. A similar
configuration and operation is provided for the tandem rotor system
with regard to rotors 4b and 5b.
[0118] As a result, the rod 31 will adjust the angle of incidence A
of the propeller blades 12, so that the upward force of the
propeller blades 12 will increase on one side of the main rotor 4a
and will decrease on the diametrically opposed side of this main
rotor. A similar configuration and operation is provided for the
tandem rotor system with regard to rotors 4b and 5b.
[0119] Since the relative position of the main rotor 4a and the
auxiliary rotor 5a are selected such that a relatively immediate
effect is obtained. This change in the upward force makes sure that
the rotor shaft 8a and the body 2 are forced back into their
original position of equilibrium.
[0120] A second effect is that, since the distance between the far
ends of the vanes and the plane of rotation 14 of the main rotor 4a
is no longer equal and since also the vanes 28 cause an upward
force, a larger pressure is created between the main rotor 4a and
the auxiliary rotor 5a on one side of the main rotor 4a than on the
diametrically opposed side. A similar configuration and operation
is provided for the tandem rotor system with regard to rotors 4b
and 5b.
[0121] A third effect plays a role when the helicopter begins to
tilt over to the front, to the back or laterally due to a
disturbance. Just as in the case of a pendulum, the helicopter will
be inclined to go back to its original situation. This pendulum
effect does not generate any destabilizing gyroscopic forces as
with the known helicopters that are equipped with a stabilizer bar
directed transversally to the propeller blades of the main rotor.
It acts to reinforce the first and the second effect.
[0122] The effects have different origins but have analogous
natures. They reinforce each other so as to automatically correct
the position of equilibrium of the helicopter 1 without any
intervention of a pilot.
[0123] If necessary, this aspect of the disclosure may be applied
separately, just as the aspect of the auxiliary rotor 5a can be
applied separately to a helicopter having a main rotor 4a combined
with an auxiliary rotor 5a. A similar configuration and operation
is provided for the tandem rotor system with regard to rotors 4b
and 5b.
[0124] In practice, the combination of both aspects makes it
possible to produce a helicopter which is very stable in any
direction and any flight situation and which is easy to control,
even by persons having little or no experience.
[0125] It is clear that the main rotor 4a and the auxiliary rotor
5a are not necessarily be made as a rigid whole. The propeller
blades 12a and the vanes 5a can also be provided on the rotor head
7a such that they are mounted and can rotate relatively separately.
In that case, for example, two rods 31 may be applied to connect
each time one propeller blade 12a to one vane 5a. A similar
configuration and operation is provided for the tandem rotor system
with regard to rotors 4b and 5b.
[0126] It is also clear that, if necessary, the joints and hinge
joints may also be realized in other ways than the ones
represented, for example by means of torsion-flexible elements.
[0127] In the case of a main rotor 4a having more than two
propeller blades 12, one should preferably be sure that at least
one propeller blade 12a is essentially parallel to one of the vanes
5a of the auxiliary rotor. The exact angle is determined by testing
and can be different from zero. The joint of the main rotor 4a is
preferably made as a ball joint or as a spindle 15 which is
directed essentially transversely to the axis of the oscillatory
shaft 30 of the auxiliary rotor 5a and which essentially extends in
the longitudinal direction of the one propeller blade 12a concerned
which is essentially parallel to the vanes 5a. A similar
configuration and operation is provided for the tandem rotor system
with regard to rotors 4b and 5b.
[0128] In another format, the helicopter comprises a body, and a
main rotor with propeller blades which is driven by a rotor shaft
on which the blades are mounted. An auxiliary rotor is driven by
the rotor shaft of the main rotor and is provided with vanes from
the rotor shaft in the sense of rotation of the main rotor.
[0129] The auxiliary rotor is mounted in a swinging relationship on
an oscillatory shaft and the swinging motion being relatively
upwardly and downwardly about the auxiliary shaft. The auxiliary
shaft is provided essentially transverse to the rotor shaft of the
main rotor. The main rotor and the auxiliary rotor are connected to
each other by a mechanical link, such that the swinging motion of
the auxiliary rotor controls the angle of incidence of at least one
of the propeller blades of the main rotor.
[0130] The angle of incidence of the rotor in the plane of rotation
of the rotor and the rotor shaft may vary. An auxiliary rotor
rotatable with the rotor shaft is for relative oscillating movement
about the rotor shaft. Different relative positions are such that
the auxiliary rotor causes the angle of incidence the main rotor to
be different. A linkage between the main and auxiliary rotor causes
changes in the position of the auxiliary rotor to translate to
changes in the angle of incidence.
[0131] The propeller blades of the main rotor and the vanes of the
auxiliary rotor respectively are connected to each other with a
mechanical linkage that permits the relative movement between the
blades of the propeller and the vanes of the auxiliary rotor. A
joint of the main rotor to the propeller blades is formed of a
spindle that is fixed to the rotor shaft of the main rotor.
[0132] The mechanical link includes a rod hinge mounted to a vane
of the auxiliary rotor with one fastening point and is
hinge-mounted with another fastening point to the propeller blade
of the main rotor.
[0133] Tandem helicopters have two rotors of more or less similar
diameter the rotors are disposed along the helicopter body
typically one at each end. The tip rotor paths may be overlapping
to a certain extend. In that case one rotor is positioned higher
than the other to avoid that the rotor blades collide.
[0134] FIG. 7 represents a typical configuration. Both rotors
exercise a lift force to compensate for the weight of the body. If
the combined lift force exceeds the weight of the tandem, there
will be lift off.
[0135] Stability and equilibrium of the tandem helicopter can be
analyzed in 4 dimensions that need control to keep the tandem on a
spot in space, or along a desired trajectory. These controls can be
active (by the pilot, or assisted by electronics), or passive (by
aerodynamic and mechanical design).
[0136] These dimensions are represented in FIGS. 10 and 11. [0137]
forward/backward (100) [0138] sideward left/right (200) [0139]
up/down vertical (300) [0140] yaw (400)
[0141] These 4 dimensions have no absolute reference in space.
Therefore, constant corrections have to be performed in flight to
keep the tandem flying as desired. Both in real size and hobby/toy
tandems, it is generally known that this implies very specific and
complicated set of stabilizing devices like gyro's and feedback
systems, on top of permanent pilot controls.
[0142] To accomplish stability in dimension 100 and 200, and to a
certain extent dimension 400, the tandem helicopter is equipped
with autostable rotors as described in FIGS. 10 and 17. This rotor
system wants the helicopter to resist by rotor design any deviation
in dimensions 100 and 200, and to a certain extent dimension
400.
[0143] Dimension 300 usually does not require anything more than
the input of the pilot to choose and keep the desired altitude, or
climbing and descending speed.
[0144] Dimension 400, the yaw around the vertical axis needs to
deal with the torque effects of the main rotors, and any external
disturbances that induce yaw changes.
[0145] A rotor produces torque as a side effect of the thrust
generated. This torque will go against the direction of rotation of
the rotor. In a classical helicopter with main and tail rotor, this
torque is compensated by the tail rotor. If no such compensation
existed, the body would rotate around the vertical axis in a
direction against the rotation of the rotor. The main rotor turning
in a clockwise direction induces a torque on the body in counter
clockwise direction. To keep the body from turning permanently
around its vertical axis, the tail rotor is added to compensate for
torque with a sideward force.
[0146] In tandem helicopters as shown in FIGS. 12 and 13, the two
rotors are turning so that the rotation of one rotor 1000 in
direction 1100 (clockwise) creates a torque on the body 2 in
direction 113 (counterclockwise) around the center axis 500. The
rotation of the other rotor 2000 in direction 1200
(counterclockwise) creates a torque on the body in direction 114
(clockwise) around the center axis of that rotor. This is
illustrated in FIG. 13.
[0147] Torque 113 and torque 114 are in a perfect case of equal
size, however of opposite direction. Therefore, they annulate and
the body of the tandem does not rotate by itself.
[0148] Yaw Behavior
[0149] That perfect case assumes that both rotors turn at identical
speed, have identical drag, have identical lift, and that no
external disturbances like air gusts and turbulences have
influence.
[0150] In reality, none of this is absolutely true. So although the
body more or less keeps its yaw position, it will constantly and
randomly change direction because of all the above factors. It is
up to the pilot, assisted by eventual gyro stabilizer, or other
devices, to correct for that.
[0151] The smaller the model is, the more these factors have effect
due to the lower inertia of the tandem, requiring speedier
correction input from the pilot.
[0152] Yaw Instability
[0153] The counter rotation configuration annulates torque on the
body. However, it causes a problem related to yaw stability.
[0154] Consider art tandem helicopter in a hovering position, and
suppose it is in perfect still position in hover flight. This is
shown in FIG. 13. The rotor 1000 and rotor 2000 turn in opposite
direction. The rotor 1000 and rotor 2000 create identical lift
forces 300 and 400. The body is horizontal.
[0155] Consider the same tandem helicopter in hovering position,
and suppose that as the result of any of the effects described (air
gusts, turbulence, slight change in relative rotor rpm, etc) the
body starts turning in one direction (clockwise in this example),
around the vertical centerline 500 of the tandem helicopter of FIG.
13. The rotor 1000 and rotor 2000 turn in opposite directions.
Because of the body rotation and direction of rotation, rotor 1000
increases its rotation speed while rotor 2000 decreases rotation
speed relative to the air. Because lift force at constant pitch
varies with rotation speed, the rotor 1000 and rotor 2000 create
now different lift forces, 3000 is higher and 4000 is lower.
Because of the difference in the lift forces, the body is no longer
in equilibrium and tend to raise the front end where rotor 1000 is
and lower the back end adjacent to rotor 2000. Because of the
difference in lift forces, the torque on rotor 1000 increases, and
the torque on rotor 2000 decreases.
[0156] The changes in torque are of the same amount but in a
different direction, so they balance out each other and do not
influence the yaw disturbance.
[0157] When the body 2 starts turning in one direction (clockwise
in this example), around the vertical centerline 500 of the tandem
helicopter (FIG. 13), then the lift force along the span of one
rotor varies along the position relative to the body and the body
rotation axis. The increase/decrease in lift will be higher the
further from the body rotation axis. This further amplifies the
destabilizing of the helicopter and raises the front end where
rotor 1000 is and lowers the back end adjacent to rotor 2000 even
more.
[0158] The body 2 no longer stays horizontal and raises the high
lift rotor and lower the low lift rotor. The increase in lift of
rotor 1000 is accompanied by a move of the center of lift further
from the centerline of the helicopter (longer lever). The
associated decrease in lift of rotor 2000 is accompanied by a move
of the center of lift closer to the center line of the helicopter
(shorter lever). Both effects combined reinforce the tendency to
incline backwards caused by the differences in thrust as such. This
inclination results in unwanted and parasite backward speed. That
further destabilizes the tandem on top of the initial yaw
disturbance.
[0159] Left-Right Asymmetry in Counter-Rotating Configuration
[0160] The counter-rotating rotors create a tandem that is
symmetrical in aerodynamic, gyroscopic effects. This is supposed to
facilitate lay-out of the components, the body and the overall
design of the body.
[0161] However, counter-rotating rotors have an asymmetric effect
on the sideward thrust on the tandem body. Rotor 1000 and rotor
2000 are counter-rotating. The rotors create a down-flow of air to
create lift, but that down flow has a spiraling component in the
direction of rotation of the rotor. When the tips of both rotors
reach the center of the body 2, this spiraling air is hitting the
side of the body 2 with an airflow component.
[0162] A 3 stage effect is created on the tandem: [0163] a. The
body 2 sees a one sided thrust force, this side force tends to push
the helicopter in the direction of force 4000. [0164] b. This force
4000 makes the tandem incline to one side and both rotors incline
in an equal amount. [0165] c. The lift force is no longer vertical
but has a horizontal vector component. This vector pushes the
tandem to the opposite direction. This increases the sideward force
that hits the body 2.
[0166] So, in spite of the apparent symmetry of the counter
rotating configuration, the tandem will have a strong tendency to
lean over and slip to one side. This tendency varies with the
surface of the body, the weight of the tandem, the rotation speed
of the rotors, the relative distance from the rotor(s) to the body,
the position of the center of gravity. Overall, this tendency
increases with a decrease in weight of the tandem. A possible
solution is to move the center of gravity sideward to align the
body back to vertical.
[0167] The unidirectional tandem rotors are illustrated with
reference to the figures.
[0168] The counter rotation rotors on a tandem configuration, where
the rotor axes are at a certain distance from each other, have
destabilizing and asymmetrical effects. Yaw changes induce fore/aft
drift, and the rotor pushes the tandem to lean over and slip. The
combination of these effects makes it very hard to find a natural
trim of the tandem for stable hover without pilot correction, or
gyro, etc., on the fore/aft and sideways dimension.
[0169] The solution is to have the rotors spinning in the same
direction. When an external yaw disturbance causes the body to
rotate, then both rotors will see the same amount of decrease or
increase in rotation speed equal to the rotation speed of the
body.
[0170] Lift forces on both rotors change equally, so the body stays
horizontal. This change in lift force does make the tandem ascent
or descent. However, because there is no body inclination, this is
not a destabilizing effect.
[0171] The sideward spiraling forces of the rotor thrust still hit
the body 2, but now in opposite direction such that they cancel
out. The body does not incline, nor slips sideways.
[0172] The torque of rotor 1000 and rotor 2000, in this case of
clockwise rotation of both rotors, now adding up into a new torque.
The rotors are inclined in such a way, namely amount and direction
that a horizontal thrust force on both rotor axis creates a counter
torque that cancels out the sum of the rotor torque.
[0173] The thrust on rotor 1000 has a horizontal component centered
on the rotor 1000 axis. The thrust on rotor 2000 has a horizontal
component centered on the rotor 1000 axis. Those two forces
exercise a torque on the body 2 in the opposite direction of the
first torque. The size of thrusts depends on the inclination of the
rotors 1000 and 2000, and so does the resulting torque. When
torques are identical in size, they cancel out and prevent the body
from turning around it's vertical axis.
[0174] The required degree of inclination of the rotors depends
mainly on: [0175] the type of rotor shape and airfoil; [0176] the
horizontal distance between both rotors; and [0177] the shape of
the body 2 which also has an influence on the angle.
[0178] This inclination is relatively small and is independent of
rpm. When the rpm changes higher, for example, so does the torque
induced by the rotor. The higher rpm means a higher lift and a
higher horizontal thrust component and thus a higher corrective
thrusts. It is possible to increase rpm at one rotor, the rear
rotor for example, and decrease the rpm on the other rotor, the
front rotor, without any asymmetrical torque effects that cause the
body to turn around or yaw. This makes it possible to move the
helicopter forward or backward using this method without the need
for yaw correction.
[0179] Counter rotating rotors on tandem helicopters create
tendency to drift in the for/after and sideway direction, and
induces inclination of the body. This leads to instability in
flight unless a pilot, mechanical or electronic system creates the
necessary corrective input.
[0180] The current disclosure uses two rotors at a certain
horizontal distance one from another, rotating in the same
direction. Those rotors are inclined such that they compensate for
the torque effects induced by the spinning rotors. The effects of
yaw (pilot induced or uninitiated/unwanted) no longer create drift
in the for/after dimension, nor does it cause undesired inclination
of the body. The spiral thrust no longer inclines and drifts the
body sideways.
[0181] The body design is another element enhancing the stability
against undesired yaw affects.
[0182] The body shape of a typical tandem helicopter is determined
to an extent by functional matters. As shown in FIG. 18, there is a
need to interconnect both rotors and their drive systems, and that
leads to a long and mainly rectangular central part A. Then there
is a typical nose end B added to house the pilot(s) and a tail end
with increased surface C to act as a directional stabilizer for
forward flight. This is similar to the fins on an arrow.
[0183] The size of B and C, mainly the part that sticks out under
the E and D ends of the rotors has an impact on yaw stability.
[0184] A shape shown in FIG. 19 with extension fins F and G has a
relatively higher yaw stability, and resists and even stops any
unwanted yaw effects due to asymmetry in torque between the rotors
and external disturbances. Furthermore, when the pilot gives a
wanted yaw input, this shape dampens the effect, avoid overshooting
of the effect versus the desired effect, and acts as a `damper`.
The result is more comfort for the pilot, and a much more stable
tandem helicopter.
[0185] The reasons why this works are at least 3 fold. First, the
surfaces F and G are at the outermost distance from the centerline
H compared with the rest of the body. This is further illustrated
in FIG. 20. In case of yaw around the centerline H clockwise, for
example, the lateral surfaces F and G operate like aerodynamic
brakes, because they have to overcome the pressure of the air 101
and 102 hitting the surfaces due to the yaw rotation.
[0186] This braking effect slows down the yaw rotation, and
eventually stops it. The shape of F and G can be any desired
profile.
[0187] Secondly, the surfaces F and G are in the downwards airflow
as generated by the two rotors, and tend to align to that downward
force. This is a function similar to a vane effect.
[0188] Thirdly, If the body rotates, then the surfaces of fins F
and G will see the downflow from the rotor thrust combined with the
movement as result of the yaw, as a combined flow that no longer is
in line with the surface of fins F or G but with a certain angle of
attack. This angle of attack creates a lift force perpendicular to
the surfaces of fins F and G opposite to the direction of movement.
These lift forces 500 and 600 counter the yaw movement and further
dampen it. See FIG. 21.
[0189] The shape of the fin parts F and G can be any desirable
profile. As is shown in FIG. 22, the front extension is integrated
in the body design. The back fin G end can be a transparent foil of
plastic.
[0190] Alternatively, both extension fins F and G are made of
transparent plastic so as to respect a desired shape of a body and
yet to have the effect of yaw stabilization. This is shown in FIG.
23.
[0191] The surfaces of fins F and G can be inclined to be more or
less in line with the airflow of the incline rotorshafts the
embodiment of the rotors rotating in the same direction. This
intensifies the effect and reduces airflow friction over those
surfaces, as shown in FIGS. 24A and 24B.
[0192] The effect of increased yaw stability is also accomplished
in the case of having one of the surface of fins F or G.
Alternatively, the ratio between the surface of fins F and G can be
significantly different from 1 to 1. In that case, the effect is
still there. It may be somewhat reduced because the effects of both
rotors are not used to a full extent.
[0193] In some cases where the ratio between F and G is largely
different from 1 to 1, and due to the arrow effect briefly
described above, the helicopter only feels comfortable moving (due
to an eventual forward command given by the pilot) in the direction
80 opposite the main lateral surface of the body. This is shown in
FIG. 25.
[0194] One of the surfaces of fins F and G can be added or removed
depending on the main direction of movement. In usual flight,
helicopters will hover or fly forward, so only surface G may be
needed. This is shown in FIG. 25.
[0195] The fin extensions F and/or G can reach essentially the
outer circumferential point reached by the rotating rotor. Even if
they do not reach to the other circumferential point, there will be
a stabilizing effect.
[0196] FIG. 26 represents a system for controlling yaw. The yaw of
a tandem helicopter as illustrated in FIG. 26 with rotors turning
in the same direction can be controlled by changing the incidence
of one rotor shaft of rotor 1000 versus the other rotor shaft of
the tandem rotor 2000. This change in inclination changes the size
of the horizontal components of the lift forces. This varies the
size of the torque, which in turn varies the turning direction of
the body. One method of varying this incidence is represented in
FIG. 26. The two rotor shafts of the two rotors 1000 and 2000 are
attached to a central boom 12000. This central boom 12000 is split
in two parts 12000A and 12000B, 12000A and 12000B can rotate
against each other driven by a servo mechanism. This mechanism can
be a motor based system 3000, or use other actuators like piezo
actuators, polymer actuators, magnet/coil assemblies and comparable
technologies.
[0197] The present disclosure is not limited to the embodiments
described as an example and represented in the accompanying
figures. Many different variations in size and scope and features
are possible. For instance, instead of electrical motors being
provided others forms of motorized power are possible. A different
number of blades may be provided to the rotors.
[0198] A helicopter according to the disclosure can be made in all
sorts of shapes and dimensions while still remaining within the
scope of the disclosure. In this sense although the helicopter in
some senses has been described as toy or model helicopter, the
features described and illustrated can have use in part or whole in
a full-scale helicopter.
[0199] While the apparatus and method have been described in terms
of what are presently considered to be the most practical and
preferred embodiments, it is to be understood that the disclosure
need not be limited to the disclosed embodiments. In some cases
there may be more than two propellers and/or vanes on one or more
of the respective main rotors or tandem rotors and their respective
auxiliary rotors. Also the acute angle between the propeller and
vane can vary in extent and can be less than 10.degree. and more
than 17.degree..
[0200] Although the invention has been described in detail with
regard to a tandem helicopter, it is clear that the rotors can
cause other objects to fly in a similar stabilized manner. The body
of those objects can take different forms, for instance different
toy vehicles or toy figurines. These could be robots, insects,
motorcars, flying saucers, airplanes, or any other body type that
one may want to fly above the ground, floor or base.
[0201] It is intended to cover various modifications and similar
arrangements included within the spirit and scope of the claims,
the scope of which should be accorded the broadest interpretation
so as to encompass all such modifications and similar structures.
The present disclosure includes any and all embodiments of the
following claims.
* * * * *