Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
CONVERTIBLE AIRCRAFT
Document Type and Number:
WIPO Patent Application WO/2007/110833
Kind Code:
A1
Abstract:
A convertible aircraft comprising a main body integrating at least one substantially triangular wing (1), the main body having a recess (2) centered substantially in correspondence of the center of gravity of the aircraft; and a propulsion system associated to the main body so as to make it selectively pivoting within said recess (2) with respect to the main body, the propulsion system comprising a thrust rotor system (10,11); main motor means (33,9) for operating the thrust rotor system (10,11); and means (31,32) for adjusting the pivoting of the propulsion system with respect to the main body, apt to change the tilt of the thrust developed by the rotor system (10,11); wherein the overall assembly is such that the tilt of the axis of rotation of the rotor system (10,11) is variable in association with said pivoting so that the thrust instantaneously developed thereby is vectorially passing through the center of gravity of the aircraft.

Inventors:
MIODUCHEVSKI PAVEL (IT)
Application Number:
IB2007/051049
Publication Date:
October 04, 2007
Filing Date:
March 26, 2007
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
INTERNAT AVIAT SUPPLY I A S S (IT)
MIODUCHEVSKI PAVEL (IT)
International Classes:
B64C29/00; B64C39/04
Foreign References:
US4613097A1986-09-23
US3049320A1962-08-14
DE1947944A11970-04-16
US2876965A1959-03-10
US6343768B12002-02-05
US4613097A1986-09-23
US3049320A1962-08-14
DE1947944A11970-04-16
US6343768B12002-02-05
US2876965A1959-03-10
Other References:
AVIATION WEEK & SPACE TECHNOLOGY, 2 January 2006 (2006-01-02), pages 56
AVIATION WEEK & SPACE TECHNOLOGY, 6 February 2006 (2006-02-06), pages 36
"Aerospace Source Book 2006", 16 January 2006, article "Aviation Week & Space Technology"
Attorney, Agent or Firm:
PAPA, Elisabetta et al. (Piazza di Pietra 39, Rome, IT)
Download PDF:
Claims:

CLAIMS

1. A convertible aircraft, comprising: a main body integrating at least one substantially triangular wing (1), said main body having a recess (2) centered substantially in correspondence of the center of gravity of said aircraft; a propulsion system associated to said main body so as to make it selectively pivoting within said recess (2) with respect to said main body, comprising:

• a thrust rotor system (10,11);

• main motor means (33,9) for operating said thrust rotor system (10,11); and

• means (31,32) for adjusting the pivoting of said propulsion system with respect to said main body, apt to change the tilt of the thrust developed by said rotor system (10,11); wherein the overall assembly is such that the tilt of the axis of rotation of said rotor system (10,11) is variable in association with said pivoting so that the thrust instantaneously developed thereby is vectorially passing through said center of gravity of said aircraft.

2. The aircraft according to claim 1, wherein said main body integrates a delta wing (1), having a recess (2) centered substantially in correspondence of the center of gravity of said aircraft.

3. The aircraft according to claim 1 or 2, wherein said thrust rotor system is with twin contra-rotating rotors (10,11).

4. The aircraft according to claim 3, wherein said twin rotors comprise two contra-rotating propellers (10,11). 5. The aircraft according to one of the claims 1 to 4, wherein said propulsion system is connected to said main body by a gimbal system (4,6,3,5), so as to be thus made selectively pivoting within said recess (2) and causing a proportional variation of the direction of said thrust.

6. The aircraft according to claim 5, wherein said gimbal system comprises a first external ring (4), rotatably connected to said main body of said aircraft by means of transversal hinges (3); and a second internal ring (6), rotatably connected to said external ring (4) by means of longitudinal hinges (5).

7. The aircraft according to claim 6, wherein a rotation of said first external ring (4) about said hinges (3) by said adjusting means (31,32) causes a proportional rotation of a first angle (ω) of said thrust about a substantially transversal axis (Z) of said main body of said aircraft.

8. The aircraft according to claim 6 or 7, wherein a rotation of said second

internal ring (6) about said hinges (5) by said adjusting means (31,32) causes a proportional rotation of a second angle (γ) of said thrust about a substantially longitudinal axis (X) of said main body of said aircraft.

9. The aircraft according to one of the claims 6 to 8, wherein the axis of rotation of said transversal hinges (3) is substantially perpendicular to said substantially longitudinal axis (X) of said main body of said aircraft and vectorially passing through said center of gravity of said aircraft.

10. The aircraft according to one of the claims 6 to 9, wherein the axis of rotation of said longitudinal hinges (5) is substantially perpendicular to said axis of rotation of said transversal hinges (3).

11. The aircraft according to one of the claims 1 to 10, wherein said main motor means (33) for operating said thrust rotor system (10,11) is integrated in one of the motor nacelles (9), associated through a rotary shaft to said thrust rotor system (10,11). 12. The aircraft according to claim 11 when dependent from one of the claims 5 to 10, wherein said motor nacelle is made integral to said gimbal system. 13. The aircraft according to claim 12 when dependent from one of the claims 6 to 10, wherein said motor nacelle (9) is made integral to said second internal ring (6) by means of substantially beam-shaped structural members (7,8). 14. The aircraft according to one of the claims 6 to 13, wherein said means for adjusting the pivoting of said propulsion system with respect to said main body comprises electromechanic means (31,32) of rotation of said first external ring (4) and of said second internal ring (6), so as to change the direction of said thrust..

15. The aircraft according to claim 14, wherein said rotation means comprises reduction gears (31) and electric motors (32) in cooperation with said hinges (3,5).

16. The aircraft according to one of the claims 1 to 15, wherein said main motor means (33) is of turbo-propeller type.

17. The aircraft according to claim 16 when dependent from one of the claims 6 to 15, wherein said gimbal system comprises an air inlet for sucking comburent air for said turbo-propeller.

18. The aircraft according to claim 17, wherein said air inlet for said turbo- propeller is integrated in said second internal ring (6).

19. The aircraft according to one of the claims 16, 17 or 18 when claim 16 is dependent on one of the claims 13 to 15, wherein said structural members (7,8) are substantially section bar-shaped and said turbo-propeller main motor means comprises a compressor (24); a turbine (25) and exhaust gas ducts (26) obtained in the section-formed structure of said beam (7).

20. The aircraft according to claim 19, comprising outlet chambers (27) for said exhaust gases, integrated in said second internal ring (6) so as to be associated to said exhaust gas ducts (26).

21. The aircraft according to claim 20, wherein said outlet chambers (27) are positioned inside an angular sector (2β) of said second internal ring (6) comprised in a range from +30° to -30° with respect to the axis of the section-formed structure of said beam (7) in which said exhaust gas ducts (26) are obtained.

22. The aircraft according to one of the claims 13 to 21, wherein on said substantially beam-shaped structural members (7,8) there are applied ailerons (16,17) controllable by control means installed on said motor nacelle (9).

23. The aircraft according to one of the claims 6 to 22, wherein said transversal hinges (3) are installed on pylons (21) mounted above said wing (1), at a height such that, with regard to the arrangement of the rotation of said thrust about a substantially transversal axis (Z) of said main body of said aircraft of any one value of said first angle (ω), said external ring (4) is anyhow spaced from the takeoff/landing surface for all of the corresponding configurations it can assume, so that no interferences are created.

24. The aircraft according to claim 23, wherein said external ring (4) is spaced from the takeoff/landing surface when in the configuration corresponding to said first angle (ω) substantially equal to 90°.

25. The aircraft according to claim 23 or 24, wherein said pylons (21) are two and arranged substantially symmetrically with respect to a substantially longitudinal axis (X) of said main body of said aircraft.

26. The aircraft according to claim 25, wherein to each of said two pylons (21), it is fixed, through a respective transversal axis, a further wing (22) substantially trapezium-shaped, so as to attain an increased span of said aircraft.

27. The aircraft according to claim 26, wherein the pitch angle of said further wing (22) is adjustable through a transversal hinge (46) connected to an actuation device (47). 28. The aircraft according to one of the claims 1 to 15 and 22 to 27, wherein said main motor means is electric motor means (33).

29. The aircraft according to claim 28 when dependent from one of the claims 23 to 27, wherein said electric motor means (33) is electrically connected through transmission lines (34) with power units (29,30) installed on respective nacelles in correspondence of said pylons (21).

30. The aircraft according to claim 29, wherein said power units comprise a motor (29) and a generator (30).

31. The aircraft according to one of the claims 1 to 30, comprising a front fuselage (12), mounted frontally to said main body of said aircraft; and two lateral fuselages (37), mounted substantially above said wing (1) and connected to said main body substantially symmetrically with respect to a substantially longitudinal axis (X) of said main body of said aircraft.

32. The aircraft according to claim 31, wherein on said two lateral fuselages (37) respective fins (13) are installed, connected therebetween by a common horizontal tail surface (40).

33. The aircraft according to one of the claims 1 to 30, comprising a substantially tricycle landing gear, said landing gear comprising a front wheel (19) placed beneath said front fuselage and two rear wheels (20) respectively placed beneath said lateral fuselages (37) and extractable from respective nacelles (15).

34. The aircraft according to one of the claims 31 to 33, wherein said front fuselage (12) comprises a cockpit (35) and a passenger cabin (36). 35. The aircraft according to one of the claims 31 to 34, wherein each of said lateral fuselages (37) comprises a compartment (38) apt to house a power unit and a passenger cabin (39)

36. The aircraft according to one of the claims 31 to 35, wherein said front fuselage (12) and said lateral fuselages (37) comprise a watertight bottom apt to allow in- water translation of said aircraft.

37. The aircraft according to one of the claims 34 or 35, wherein said passenger cabin (12) is convertible to cargo transport and/or cistern and/or tank integrating devices for collecting liquid for fire-extinguishing operations and the like from reservoirs.

Description:

CONVERTIBLE AIRCRAFT

DESCRIPTION

The present invention relates to the field of general aviation and may be applied indiscriminately both to conventional aircrafits with onboard pilot and to highly automated aircrafts with no onboard pilot (unmanned) (UAV 5 UCAV 5 UAS)

In the aviation field it is known the convertible aircraft V22 Osprey, developed by Bell Helicopter Textron and Boeing aeronautic industries ( Aviation Week & Space Technology, January 2, 2006, page 56)

Moreover, Bell Helicopter -Textron have also developed an unmanned aircraft, UAS TR918 Eagle Eye, which has an aeromechanical scheme similar to the V22 Osprey {Aviation Week & Space Technology, February 6, 2006, page 36).

The drawbacks of a V22 Osprey-type convertible aircraft are the following:

a) The two heavy engines are installed each at the wing ends, the span is equal to the distance between axes and engines; this fact requires great rigidity of the wing structure, considerably increasing the weight of the structure.

b) V22 Osprey engines and TR918 Eagle Eye rotors must be synchronized through a mechanical transmission placed in the wing structure, increasing the weight of the entire structure.

c) Engines and rotors are placed at the end of each wing. Engines, rotors and transmission are sources of powerful vibrations and noise..

d) The Osprey-type system does not ensure flight stability and safety in case of a rotor (engine)malfunctioning and/or breaking.

e) The span in this Osprey-type aeromechanical system must necessarily be not extended above a certain limit. If the span exceeds this limit the problem of aeroelastic vibrations becomes unsolvable.

f) The Osprey-type system is not capable of flying or landing at a relatively low speed, as a normal-scheme aircraft can do.

Object of the present invention is to solve the technical problems of the convertible aircraft and provide an aeromechanical scheme of the convertiplane as free from the abovementioned drawbacks.

Such a problem is mainly solved by an apparatus according to claim 1. The present invention provides several relevant advantages. One of the main advantages is that the invention increases the efficiency and the safety of the convertible aircraft. The present invention provides for the center of gravity of the engine with coaxial rotors to coincide with the center of gravity of the convertible aircraft. Span and wing surface of the convertiplane may be designed and built at the desired features: speed, distance and altitude of flight, of takeoff and of landing

Other advantages, features and the operation modes of the present invention will be made apparent from the following detailed description of some embodiments thereof, given by way of example and not for limitative purposes.

Reference will be made to the figures of the annexed drawings, wherein:

Fig. 1 shows a plan view of a first embodiment of triangular-wing convertible aircraft;

Fig. 2 shows a plan view and a cross-sectional view of the propulsion apparatus of the convertible aircraft;

Figs. 3 and 4 show respectively a front view and a side view of the convertible aircraft of Fig. 1;

Fig. 5 shows a plan view of a second embodiment of the triangular- wing convertible aircraft;

Figs. 6 and 7 show respectively a front view and a side view of a second embodiment of the convertible aircraft of Fig. 5;

Figs. 8 and 9 show respectively a front view and a plan view of a third embodiment of the convertible aircraft;

Fig. 10 shows a plan view and a cross-sectional view of the propulsion apparatus of the convertible aircraft with a turbo-propeller engine;

Fig. 10a shows a view along direction A of the propulsion apparatus of Fig. 10;

Fig. 11 shows a schematic plan view of the power units, and of the operation devices of the propulsion apparatus of the convertible aircraft;

Fig. 12 shows a side view of the convertible aircraft with the schematics of the aerodynamic forces;

Figs. 13 and 14 show respectively: a plan view and a side view of an embodiment of the convertible aircraft with three fuselages.

Referring to Figs. 1 to 4, there may be seen a first embodiment of the triangular- wing convertible aircraft, mainly comprising:

a triangular wing 1, a front fuselage 12, two fins 13, each with rudder 18, elevator 14 manufactured in two sections, which may also serve as ailerons, two nacelles 15 comprising the main landing gears 20 and electromechanic control devices. The wing 1 has a circular hole 2 with the center corresponding with the center of gravity of the aircraft. Inside the hole 2 an external ring 4 is hung to the horizontal and transversal hinges 3. Inside the external ring 4 the air sucking ring 6 is hung to the longitudinal hinges 5. At the center of the ring 6 it is located the propulsor nacelle 9, which is fixed to the structure of the section beams 7 and 8. The axes of the section beams 7 and 8 are substantially perpendicular. The beams 7 and 8 are rigidly connected with the ring 6. Referring to Fig. 2, the convertible aircraft has two coaxial contra-rotating rotors 10 and 11. Each rotor has a variable-pitch four-blade propeller. The external ring 6 may be installed with the aid of electromechanic apparatuses at the angle ω with respect to the XZ plane of the wing 1. The angle ω is the angle between propulsion vector (thrust) on XY plane and Y axis perpendicular to the XZ plane of the wing 1. For vertical takeoff, ω =O. For flight under maximum speed conditions, ω= 90°. Theoretically, angle ω may range from O to ± 180°. The propulsion vector (thrust) may be tilted with the aid of electromechanic mechanisms to the angle γ on YZ plane with respect to Y axis. The control of the angles ω and γ of the propulsion vector provides for the significant increase of stability and maneuverability of the

convertible aircraft under all flight conditions: under helicopter conditions and under airplane conditions. The great advantage of the convertible aircraft according to the present invention is that the propulsion vector (thrust) always runs through the center of gravity of the aircraft, whereas the direction of this vector is variable. The ailerons 16 and 17 at the beam 7 and 8 serve for accurate control of the aircraft during vertical takeoff and landing and during low-speed flight, low speed at which other aerodynamic control means are not effective. The convertible aircraft in the embodiment corresponding to Figs 1 to 4 can take off and land as helicopter and fly as airplane at maximum speed in position ω = 90° (Fig. 3). Figs. 5, 6, 7 respectively show a plan view, a front view and a side view of the convertible aircraft with two pylons 21 installed on the wing above the nacelle 15; in this embodiment of the convertible aircraft, the axis of the transversal hinges 3 is raised with respect to the plane of the wing 1, so that the external ring 4 in vertical position (ω= 90°) has a guaranteed gap with respect to the ground, as shown in Figs. 6 and 7. In this embodiment the convertible aircraft can take off and land like a conventional airplane; this is useful to transport big loads (cargo). The convertible aircraft according to the present invention can fly with a large angle of attack, as the rotors in position (ω= 90°) provide to convey air in a sufficiently fast amount onto the top surface of the wing 1 to prevent air flow detachment from the surface of the wing 1. The convertible aircraft in the embodiment shown in Figs. 5 and 6 may carry out short-distance takeoff and landing by positioning the rotor at angle ω= 90°- 110°. Figs. 8 and 9 show respectively: a front view and a plan view of an embodiment of the convertible aircraft for long-distance and/or long-lasting flights and/or option of big load (cargo) transport. In this embodiment, the convertible aircraft comprises a second wing 22 with larger span: the left and right portions of the wing 22 are connected with the structure of the pylons 21 through hinges 46 which serve for adjusting the pitch of the wing 22 with respect to the plane of the wing l.The electromechanisms 47 serve for controlling the pitch of the wing 22. The triangular wing 1 in this embodiment of the convertible aircraft may have the span less extended (Fig. 5) than the two first embodiments of the convertible aircraft of Figs. 1 and 5. The wing 1 in Fig. 9 has the elevator 14, and ailerons 23 placed on the wing 22. Figs. 10 and 10a show a schematic drawing of installation of a turbo-propeller engine fixed to the section-formed structure of the beams 7 and 8. 24 axial compressor, 25 turbine, 7 exhaust gas ducts inside the beam structure, 27 sectorial outlet chamber for exhaust gases. Fig. 10a shows a view taken along direction A (Fig. 10) where there are four chambers 27 for outletting exhaust gases into the structure of the ring 6. Angle γ must not exceed 30° of tilt in order to eliminate

chances of contact between surfaces of the wing 1 and exhaust gases. The surfaces of the wing I 5 in this configuration, are kept apart from the exhaust gases by the large air layer generated by the propellers. Fig. 11 shows a schematic plan view of the propulsion system with an electric motor installed in the nacelle 33, and of the coaxial contra-rotating rotors 11 and 12. Two power units 29 (motor) - 30 (generator) are installed inside the nacelles of the pylons 21, electric cables run inside the structure of the section bar 8 and join the electric motor of the nacelle 33. Electric motors 32 and reduction gears 31 serve for controlling the angle ω of the propulsion vector (thrust). Alike electromechanic mechanisms, which serve for controlling the angle γ, are installed in the structure of the external ring 4. The use of the electric motor for propeller can significantly decrease aircraft weight, simplify propeller control and increase flight safety, since in case of breakage of one of the two power units it creates no serious danger to aircraft flight. Fig. 12 shows an aerodynamic scheme of the convertible aircraft: Y w - lift of wing 22,

Xw- aerodynamic drag of wing 22,

Ya and Xa are respectively lift and aerodynamic drag of the wing 1

Yf and Xf are respectively lift and aerodynamic drag of the front fuselage 12 with the front portion of the wing 1. G - aircraft weight

13 - fin with rudder 18. u - relative speed of air during flight, α f - angle of attack of the wing 1. α w - angle of attack of the wing 22. T- propulsion vector (thrust), β=α f - α w

During flight, all aerodynamics, inertial, thrust and weight are in balance. The convertible aircraft according to the present invention can fly at low speed u∞ at the large angle α f producing sufficient lift as the top surface of the wing 1 remains under the air flow of the propeller with a speed u r , and the wing 22 remains at the angle of attack with optimal α w which is much smaller than α f . Figs. 13 and 14 show respectively a plan view and a side view of the convertible aircraft with passenger cabins, wherein; 35 -cockpit, 36,39- passenger cabins,

39- power unit compartment, 37- lateral fuselage,

1- small-span wing, 22- large-span wing,

4 and 6- external ring and air sucking ring of the propeller (coaxial rotors), respectively 13- fin,

18- rudder,

40- horizontal tail surface,

41- elevator,

42,43- front door and rear door, respectively 44,45- passenger cabin windows.

In this embodiment the convertible aircraft has three fuselages: a front fuselage with two lateral fuselages (37) with power unit compartments (38) and passenger cabins

(39). The three fuselages of the aircraft are dimensioned so that the center of gravity of the aircraft coincides with the center of the propulsion system (rings 4 and 6). The span of the wing 1 is equal to the diameter of the ring 4 of the propulsion system.

The most important features of the convertible aircraft can be calculated for each of the above-mentioned embodiments thereof. The thrust of the propulsion system may be calculated with the following formula: T=X 1 POO 2 D 4 , in kg

Wherein: p - air density at flight altitude, (kgsec 2 /m 4 ) ω - angular velocity of rotors, (rad/sec)

D - rotor diameter, (m) Xi - non-dimensional coefficient, which depends on the aerodynamic features of the rotor.

The motor power required to produce the thrust T may be calculated with the following Formula:

W= χ 2 3 D 5 , (kgm/sec) wherein:

% 2 - non-dimensional coefficient, which depends on %\ and other aerodynamic features of the rotors. During vertical takeoff, T=G, where G is the aircraft weight.

WZG=WZT= χsooD

Where χ 3 = χi /χ_..

In Aerospace Source Book 2006 (Aviation Week & Space Technology, January 16,

2006), there have been published all technical data related to present-day helicopters

and tilt rotors. By analyzing these data we can conclude that, statistically, for heavy- and medium- weight helicopters W/G-37.5 m/sec. For light-weight helicopters W/G~22,5 m/sec. These data correspond to ω =12 1/sec or frequency f=2 rps (120 rpm). Another interesting parameter is the load per air unit of the rotor: p=4G/πD 2 , (kg/m 2 )

By analyzing the data in Aerospace Source Book 2006 we can conclude that, statistically, for heavy- arid medium-weight helicopters p -40 kg/m 2 ; for lightweight helicopters p -20 kg/m 2 ; for V22 Osprey p -120 kg/m 2 ; for BA609 p -80 kg/m 2 . The BA609 convertiplane has the rotor with D = 8m and a weight G = 7476 kg.

The V22 convertiplane has the rotor with D =I l .4m, and a weight G = 24475kg.

From the preceding formulas there ensues p=4G/πD 2 =4T/πD 2 =(4 χ lP /π)(ωD) 2

From the statistical data we have seen that value (ωD) is constant for the group to which the helicopter type belongs. (ωD) is greater for heavier helicopters, as the rotor diameter D increases.

The rotors of the convertiplanes V22 and BA 609 respectively have a diameter D smaller than the diameter of the helicopter rotor. In order to meet the value of parameter (p), which for helicopters is much greater than this parameter, the rotors of these convertiplanes have a higher value of parameter ω (ω «25 1/sec). The convertible aircraft according to the present invention in the embodiment shown in Figs. 13,14 may have parameter ω and D similar to that for a heavy-weight helicopter. In the embodiment of light-weight UAV/ UCAV aircraft corresponding to Figs. 1,3,4 and 5,6,7, and 8,9, the convertible aircraft may have smaller rotor diameter and higher angular velocity ω.

From experimental research conducted by TsAGI (Central Aerohydrodynamic Institute, Zhukovski, Russia) it is known that a propulsor containing the propeller inside a ring can yield a 40% to 120% increase of the thrust. Thus, a convertiplane according to the configuration proposed by us will exhibit a considerable increase of the thrust during takeoff and landing.

Rotor diameter decreases at the increasing of the number of blades.

It is important to optimize the rotation speed (rpm) of the rotors by means of the speed changing system.

During cruising flight, the power required for propulsion in a substantially horizontal flight may be 10 times less than the power required for vertical takeoff.

Therefore, fuel consumption during a substantially horizontal flight decreases significantly, providing the option of a prolonged cruising range.

Table 1 shows the potential features of the convertible aircraft in different embodiments thereof.

Table 1

From the data in Table 1 it follows that the convertible aircraft exhibits, in all of its embodiments, technical features much more advantageous than those of present-day aircrafts.