U.S. patent application number 09/737825 was filed with the patent office on 2002-06-20 for aircraft.
Invention is credited to Ingram, David Barry.
Application Number | 20020074452 09/737825 |
Document ID | / |
Family ID | 10867103 |
Filed Date | 2002-06-20 |
United States Patent
Application |
20020074452 |
Kind Code |
A1 |
Ingram, David Barry |
June 20, 2002 |
AIRCRAFT
Abstract
An aircraft capable of vertical take off and normal cruise
flight has a fuselage and a pair of wings, the wings being movable
relative to the fuselage from a rearwardly swept position to which
the wings are moved for vertical take off, to a spread position to
which the wings are moved for normal cruise flight.
Inventors: |
Ingram, David Barry;
(Crewkerne, GB) |
Correspondence
Address: |
LARSON & TAYLOR, PLC
1199 NORTH FAIRFAX STREET
SUITE 900
ALEXANDRIA
VA
22314
US
|
Family ID: |
10867103 |
Appl. No.: |
09/737825 |
Filed: |
December 18, 2000 |
Current U.S.
Class: |
244/7B |
Current CPC
Class: |
B64C 29/02 20130101;
Y02T 50/10 20130101; B64C 3/40 20130101; Y02T 50/14 20130101 |
Class at
Publication: |
244/7.00B |
International
Class: |
B64C 027/22 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 29, 1999 |
GB |
9930728.2 |
Claims
1. An aircraft having a fuselage and a pair of wings, and being
capable of vertical take off with the fuselage generally vertical
and normal cruise flight with the fuselage generally horizontal the
wings being movable relative to the fuselage from a rearwardly
swept position to which the wings are moved for vertical take off,
to a spread position having a higher aspect ratio to which the
wings are moved for normal cruise flight.
2. An aircraft according to claim 1 wherein the aircraft has a tail
structure including tail wings and, prior to take off, the aircraft
sits on the tail structure.
3. An aircraft according to claim 2 wherein the tail structure is
of cruciform configuration.
4. An aircraft according to claim 1 wherein the aircraft is capable
of both vertical take-off and landing and the wings are moveable to
the rearwardly spread position during landing as well as
take-off.
5. An aircraft according to claim 1 wherein thrust for at least
take-off is provided by a rotor/propeller system.
6. An aircraft according to claim 4 wherein thrust for vertical
landing is provided by a propeller system.
7. An aircraft according to claim 5 wherein the rotor system
includes a pair of contra-rotating rotors which mutually counteract
torque reactions.
8. An aircraft according to claim 6 wherein the rotor system
includes a pair of contra-rotating rotors which mutually counteract
torque reactions.
9. An aircraft according to claim 8 wherein the rotor/propeller
system is provided at or adjacent a nose structure of the
aircraft.
10. An aircraft according to claim 1 wherein thrust for at least
take-off is provided by a jet thrust means.
11. An aircraft according to claim 4 wherein thrust for vertical
landing is provided by jet thrust means.
12. An aircraft according to claim 10 wherein the jet thrust means
is provided in the fuselage at a tail end of the aircraft.
13. An aircraft according to claim 11 wherein the jet thrust means
is provided in the fuselage at a tail end of the aircraft.
14. An aircraft according to claim 5 wherein a rotor system is used
to achieve thrust during at least take-off and thrust means are
provided by a jet thrust during normal cruise flight.
15. An aircraft according to claim 1 wherein the aircraft is an
un-manned aerial vehicle.
16. A method of operating an aircraft having a fuselage and a pair
of wings and being capable of vertical take off with the fuselage
generally vertical and normal cruise flight with the fuselage
generally horizontal, the method including moving the wings
relative to the fuselage to a rearwardly swept position for
vertical take off, operating a thrust means to achieve vertical
take-off, manoeuvring the aircraft to the normal cruise flight
condition, and moving the wings relative to the fuselage to a
spread position for normal cruise flight.
17. A method according to claim 16 wherein the wings are moved
relative to the fuselage from the swept position to the spread
position during the transition from vertical flight to normal
cruise flight.
18. A method according to claim 16 wherein the wings are moved from
the spread position to the rearwardly swept position during
transition from normal cruise flight to vertical flight prior to
vertical landing.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to an aircraft and more particularly
to an aircraft which is capable of vertical take off and preferably
also, vertical landing (VTOL).
DESCRIPTION OF THE PRIOR ART
[0002] Such aircraft are known which are of configurations which
have come to be known as "tailsitters", an example being disclosed
in U.S. Pat. No. 5,289,994. In this previous specification, a VTOL
aircraft is described which has a pair of fixed wings which provide
lift in normal horizontal or cruise flight, and helicopter-like
rotors or propellers to provide lift during vertical take off and
landing, and thrust in cruise flight.
[0003] On the ground, the aircraft is adapted to sit on a tail
structure thereof with a fuselage extending generally
vertically.
[0004] Other examples of similar aircraft are disclosed in U.S.
Pat. No. 2,622,826, U.S. Pat. No. 2,859,003, and U.S. Pat. No.
5,516,060. In the latter two prior proposals, jet thrust instead of
rotor/propeller thrust is utilised. In each of these examples, the
wings which provide lift during normal horizontal flight are fixed
relative to a fuselage thereof, although the wings may be provided
with ailerons and the like for cruise flight control.
[0005] Such fixed wings having a relatively high aspect ratio are
capable of achieving good cruise efficiency especially in the
generally low speed horizontal flight regime of such aircraft but
the fixed spread position impairs hover and low speed stability and
control in the vertical take off and landing mode.
SUMMARY OF THE INVENTION
[0006] According to one aspect of the invention we provide an
aircraft having a fuselage and a pair of wings and being capable of
vertical take off with the fuselage generally vertical and normal
cruise flight with the fuselage generally horizontal, the wings
being movable relative to the fuselage from a rearwardly swept
position to which the wings are moved for vertical take off, to a
spread position having a higher aspect ratio to which the wings are
moved for normal cruise flight.
[0007] By virtue of the wings being so movable, improved low speed
performance and control, particularly during and immediately after
vertical take-off can be achieved with the wings in the rearwardly
swept position.
[0008] It is well known in conventional aircraft which take off and
land generally horizontally to provide so called swing wings, by
means of which a wing spread position can be provided during
take-off and landing, and a rearwardly swept position can be
provided during high speed cruise flight. In an aircraft in
accordance with the invention which is capable of at least vertical
take off, an opposite regime is adopted.
[0009] By moving the wings during vertical take off, to a
rearwardly swept position, the distance of wing control surfaces,
such as ailerons/flaps or the like from a centre of gravity of the
aircraft, is increased, to provide a lengthened moment arm to
increase the control forces which can be achieved by moving the
control surfaces.
[0010] Furthermore, with the wings in the rearwardly swept
position, the space required for storage of the aircraft is
reduced.
[0011] In general, VTOL aircraft of the kind with which the
invention is primarily concerned are not required to achieve very
high speed forward cruise flight, but may achieve cruise flight
speeds in the range 150 to 200 knots. At such relatively low speeds
the higher aspect ratio of the wings in the spread position
provides an improved lift/drag ratio to optimise the efficiency of
the aircraft during normal cruise flight.
[0012] If the invention was applied to an aircraft which was
capable of higher speed forward flight, if desired in such high
speed mode of operation, the wings may be swept rearwardly to an
interim or fully swept position to reduce the aspect ratio and to
improve efficiency at such higher forward speeds.
[0013] The aircraft of the invention may have an e.g. cruciform
configuration tail structure including tail wings and, prior to
take off, the aircraft may sit on the tail structure.
[0014] In a preferred arrangement, the aircraft is capable of both
vertical take-off and landing. Thus preferably the wings are
moveable to the rearwardly swept position during landing as well as
take-off.
[0015] Thrust at least for take-off, and landing where the aircraft
is capable of vertical landing, may be provided by a
rotor/propeller system, which may include a pair of contra-rotating
rotors which mutually counteract torque reactions. Such rotor
system may be provided at or adjacent a nose structure of the
aircraft.
[0016] Alternatively or additionally, thrust at least for take-off,
and landing where the aircraft is capable of vertical landing, may
be provided by a jet thrust preferably provided in the fuselage
e.g. at a tail end of the aircraft.
[0017] If desired, a rotor system may be used to achieve thrust
during at least take-off, and landing where the aircraft is capable
of vertical landing, and thrust may be provided by a jet thrust
during normal cruise flight.
[0018] A rotor system is preferred for at least take-off, and
landing where the aircraft is capable of vertical landing for finer
stability and control, for manoeuvring and hovering.
[0019] The aircraft may be used as an un-manned aerial vehicle.
[0020] According to a second aspect of the invention we provide a
method of operating an aircraft having a fuselage and a pair of
wings, and being capable of vertical take-off with the fuselage
generally vertical and normal cruise flight with the fuselage
generally horizontal, the method including moving the wings
relative to the fuselage to a rearwardly swept position for
vertical take-off, operating a thrust means to achieve vertical
take-off, manoeuvring the aircraft to the normal cruise flight
condition, and moving the wings relative to the fuselage to a
spread position for normal cruise flight.
[0021] Preferably the wings are moved relative to the fuselage from
the swept position to the spread position during the transition
from vertical flight to normal cruise flight.
[0022] The method of the invention may include moving the wings
from the spread position to the rearwardly swept position during
transition from normal cruise flight to vertical flight prior to
vertical landing.
[0023] The aircraft to which the method of the second aspect of the
invention is applied, may have any of the features of the aircraft
of the first aspect of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The invention will now be described with reference to the
accompanying drawings in which:
[0025] FIG. 1 is an illustrative side view of an aircraft in
accordance with the invention in a vertical position prior to
vertical take-off;
[0026] FIG. 2 is an illustrative plan view of the aircraft of FIG.
1 in normal cruise flight.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] Referring to the drawings, an aircraft 10 of the kind which
is capable of vertical take-off and landing, includes a fuselage
12, and a pair of wings 13, 14. At a tail end 15 of the fuselage
there is a cruciform tail structure 18 which includes four tail
wings 19 each having an aerodynamic control surface 20.
[0028] The aircraft 10 further includes a nose structure 22 which
in this example mounts a rotor/propeller system 25 which has a
first multi-bladed rotor 28 which in use rotates in a first
direction e.g. clockwise about a longitudinal axis A of the
aircraft and is located axially outermost, and a second
multi-bladed rotor 29 which in use rotates in a second opposite
direction about axis A to the first rotor 28, the second rotor 29
being located axially innermost. Thus the rotors 28, 29 are
generally parallel and rotate in opposite directions, thus mutually
counteracting torque reactions produced by the other of the rotors
28, 29.
[0029] Referring now to FIG. 1, the aircraft 10 is shown with the
fuselage 12 in a generally vertical position prior to take-off. The
aircraft 10 sits on the cruciform tail structure 18 which is
adapted to support the weight of the aircraft 10 on the ground. The
wings 13, 14 are in a rearwardly swept position in which the wings
are moved close to the fuselage 12 and a wing quarter chord line L
is swept rearwardly at an angle .theta. from a line perpendicular
to a fuselage (longitudinal) centre line 21.
[0030] By virtue of the rearwardly swept wing position, during
vertical flight, better control and stability of the aircraft 10 is
achievable, than for an aircraft having wings in a spread position
in which the wing quarter chord line L is perpendicular or
approximately perpendicular to the fuselage centre line 21.
[0031] To achieve take-off, the rotors 28, 29 are rotated about
axis A at a sufficient speed to achieve the necessary thrust for
take-off. Thus there may be provided an engine within the fuselage
12, connected to the rotors 28, 29 by a transmission which may be
of a similar construction to that used for a helicopter main
sustaining rotor system. By virtue of the rotor system 25, the
aircraft 10 may be made to hover in vertical flight, in the same
manner as a helicopter.
[0032] Once the aircraft 10 has taken-off, the aircraft 10 may be
manoeuvred for normal cruise flight as seen in FIG. 2, in which the
fuselage 12 is generally horizontal. Such manoeuvring may be
achieved by adjusting the rotors' blades, and/or operating control
surfaces such as ailerons/flaps 40, 20 provided on the wings 13, 14
and the tail structure 15. In normal cruise flight, two of the tail
wings 19 may or may not be generally vertical or horizontal as
desired.
[0033] During transition to normal cruise flight, the wings 13, 14
are moved relatively to the fuselage 12 outwardly to a spread
position seen in FIG. 2 to reduce the angle .theta. from that shown
in FIG. 1, to an angle in which the wing quarter chord line L
extends perpendicularly or more nearly perpendicularly to the
aircraft fuselage (longitudinal) centre line 21, than when the
wings 13, 14 are in the rearwardly swept position. In this
position, the wings 13, 14 present a higher aspect ratio than when
the wings 13, 14 are in the rearwardly swept position. At least in
normal cruise, relatively slow forward flight, the higher aspect
ratio of the wing improves the control of the aircraft 10, by
providing an improved lift/drag ratio to optimise efficiency of the
aircraft 10.
[0034] During normal cruise flight, the rotors 28, 29 operate as a
propeller system to provide thrust for forward flight.
[0035] For landing the aircraft, the fuselage 12 is manoeuvred into
vertical flight and the wings 13, 14 are again moved to the
rearwardly swept position shown in FIG. 1. Thus the aircraft 10 is
landed vertically.
[0036] Although in the example described, thrust for vertical and
normal cruise flight is achieved by a rotor/propeller system 25, in
another example thrust at least for normal cruise flight, but if
desired for vertical flight too, may be achieved by a jet thrust
means such as a jet engine provided in the fuselage 12 e.g. as
indicated at J in FIG. 2, at or adjacent the tail end 15 thereof.
Thus the aircraft may have both a rotor system 25 and a jet thrust
means J to develop thrust, or a jet thrust means J or
rotor/propeller system 25 only.
[0037] Mechanisms for achieving wing movement outwardly and
inwardly relative to the fuselage are known for use on aircraft
which take-off and land conventionally i.e. in a generally
horizontal condition. It is envisaged that a similar mechanism may
be used for moving the wings 13, 14 in an aircraft in accordance
with the invention.
* * * * *