EP2625094A1 - Avion adav à trois ailes et six unités de propulsion inclinables - Google Patents

Avion adav à trois ailes et six unités de propulsion inclinables

Info

Publication number
EP2625094A1
EP2625094A1 EP11831080.4A EP11831080A EP2625094A1 EP 2625094 A1 EP2625094 A1 EP 2625094A1 EP 11831080 A EP11831080 A EP 11831080A EP 2625094 A1 EP2625094 A1 EP 2625094A1
Authority
EP
European Patent Office
Prior art keywords
aircraft
wing
flight
blades
propulsion units
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP11831080.4A
Other languages
German (de)
English (en)
Inventor
Richard David Oliver
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Oliver VTOL LLC
Original Assignee
Oliver VTOL LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US12/900,790 external-priority patent/US8616492B2/en
Priority claimed from US13/168,624 external-priority patent/US8708273B2/en
Application filed by Oliver VTOL LLC filed Critical Oliver VTOL LLC
Publication of EP2625094A1 publication Critical patent/EP2625094A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C29/00—Aircraft capable of landing or taking-off vertically, e.g. vertical take-off and landing [VTOL] aircraft
    • B64C29/0008—Aircraft capable of landing or taking-off vertically, e.g. vertical take-off and landing [VTOL] aircraft having its flight directional axis horizontal when grounded
    • B64C29/0016—Aircraft capable of landing or taking-off vertically, e.g. vertical take-off and landing [VTOL] aircraft having its flight directional axis horizontal when grounded the lift during taking-off being created by free or ducted propellers or by blowers
    • B64C29/0033—Aircraft capable of landing or taking-off vertically, e.g. vertical take-off and landing [VTOL] aircraft having its flight directional axis horizontal when grounded the lift during taking-off being created by free or ducted propellers or by blowers the propellers being tiltable relative to the fuselage
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C29/00—Aircraft capable of landing or taking-off vertically, e.g. vertical take-off and landing [VTOL] aircraft
    • B64C29/0008—Aircraft capable of landing or taking-off vertically, e.g. vertical take-off and landing [VTOL] aircraft having its flight directional axis horizontal when grounded
    • B64C29/0041—Aircraft capable of landing or taking-off vertically, e.g. vertical take-off and landing [VTOL] aircraft having its flight directional axis horizontal when grounded the lift during taking-off being created by jet motors
    • B64C29/0075—Aircraft capable of landing or taking-off vertically, e.g. vertical take-off and landing [VTOL] aircraft having its flight directional axis horizontal when grounded the lift during taking-off being created by jet motors the motors being tiltable relative to the fuselage
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C39/00—Aircraft not otherwise provided for
    • B64C39/08—Aircraft not otherwise provided for having multiple wings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENTS OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
    • B64D27/00—Arrangement or mounting of power plant in aircraft; Aircraft characterised thereby
    • B64D27/02—Aircraft characterised by the type or position of power plant
    • B64D27/04—Aircraft characterised by the type or position of power plant of piston type
    • B64D27/06—Aircraft characterised by the type or position of power plant of piston type within or attached to wing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENTS OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
    • B64D27/00—Arrangement or mounting of power plant in aircraft; Aircraft characterised thereby
    • B64D27/02—Aircraft characterised by the type or position of power plant
    • B64D27/10—Aircraft characterised by the type or position of power plant of gas-turbine type
    • B64D27/12—Aircraft characterised by the type or position of power plant of gas-turbine type within or attached to wing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T50/00—Aeronautics or air transport
    • Y02T50/40—Weight reduction

Definitions

  • the invention relates to the field of VTOL aircraft, and in particular, to an aircraft which is capable of sustained vertical flight following the loss of thrust from a propulsion unit. This means the continued safe flight following the failure of not only an engine but a gearbox or propeller/rotor.
  • the reason this search continues is that the helicopter is full of performance limitations and safety problems.
  • the performance is limited due to its limited forward speed due to retreating blade stall. It also has a limited range due to its inefficiency compared to fixed wing aircraft.
  • the limited range is further reduced by the utilization of light weight turbine engines, which do not reach any reasonable fuel efficiency until operating at high altitudes where helicopters do not normally operate.
  • the helicopter must consume much of its power simply keeping itself in the air, and approximately 15% of the power is consumed by the tail anti-torque rotor just to keep the helicopter from spinning.
  • the helicopter must also deal with high vibration levels.
  • Aircraft designers have been working on the concept of vertical takeoff and landing (VTOL) aircraft for many years.
  • VTOL vertical takeoff and landing
  • the engineering challenge consists of achieving two main goals.
  • the first is to accomplish redundant and controllable vertical flight in such a way that the very same mechanisms and equipment are required for forward flight. Any weight of exclusively vertical flight mechanisms is useless during forward flight and represents a reduction in available payload relative to a fixed wing aircraft capability.
  • the second goal consists of achieving "power matching". This simply means a successful VTOL design should require the same power in vertical flight as forward flight. Any mismatch represents excess capacity which corresponds to excess weight in one mode of flight.
  • the present invention simultaneously achieves both goals.
  • a pair of J85-GE-5 turbojets mounted within the fuselage provided approximately 5,000 pounds of thrust in normal flight.
  • the pilot could actuate a diverter valve that directed some of the exhaust gases to a pair of fans, 5 feet in diameter, located in the inboard portion of each wing.
  • the wing fans rotated in opposite directions and were covered by large hinged doors in conventional flight.
  • Exhaust gas also powered a smaller fan in the nose that provided pitch control and a measure of additional lift. All three fans together provided 16,000 pounds of vertical thrust.
  • a set of louvered vanes underneath each of the large wing fans could vector the thrust in any direction and provided yaw control. Much of the all important payload capability was consumed by the complex fan system.
  • the Ling- Temco-Vought (LTV) of Grand Prairie Texas XC- 142(A) cargo airplane is the most notable tilt wing VTOL.
  • the XC-142A first flew on September 29, 1964, and on January 11, 1965, it completed its first transitional flight.
  • My father was a design engineer at LTV when I watched this plane as a teenager. I was there when it crashed in the marshes of the lake near our home killing three test pilots due to a tail rotor drive shaft failure. This aircraft had problems with cross-linked drive shaft vibrations.
  • Vertol V-76 is an additional example of a Tilt Wing research aircraft. This aircraft configuration did not solve the failure of a gearbox, driveshaft or propeller problems.
  • the X-14 was designed using existing parts from two Beechcraft aircraft: wings, ailerons, and landing gear of a Beech Bonanza and the tail cone and empennage of a Beech T-34 (a military trainer variant of the Bonanza).
  • the X-14 first flew on 19 February 1957 as a vertical takeoff, hover, then vertical landing. The first transition from hover to horizontal flight occurred on 24 May, 1958. In 1959, its Viper engines were replaced with General Electric J85 engines. That year the aircraft was also delivered to the NASA Ames Research Center as the X-14A. It served as a test aircraft with NASA until 1981. The X-14 project provided a great deal of data on Vertical Take Off and Landing aircraft. The X-14A was a successful research aircraft. The VTOL design did not produce a practical aircraft with meaningful payload and range.
  • the MBB VJ-101 Jet Lift vehicle consisted of an F104 aircraft with tilt-able turbojet engines placed at each end of its conventional wing.
  • the problem of engine failure was not solved by this aircraft design.
  • the AV-8 Harrier uses an ejection seat as a solution for engine problems. This is a very narrow solution initially designed for forward air support of ground troops.
  • the problem of a failure of a propulsion unit is not solved by these designs.
  • the tilt jet embodiment of the present invention solves the problems of previous tilt jet configurations.
  • Tilt-Props Tri-iService/Curtiss- Wright X-19 Tandem Wing Radial Force Tilt Prop aircraft placed Tilt Props at each end of two wings, creating a two wing four Tilt-Prop design.
  • This aircraft used a cross- coupled drive shaft system to provide for an engine failure. The problem of a failure of a gearbox, shaft, or propeller is not solved by this design.
  • the aircraft is powered by twin Lycoming T-53 turbo-shaft engines that are connected by a cross-shaft and drive three-bladed, 25 ft diameter metal rotors (the size extensively tested in a wind tunnel).
  • the engines and main transmissions are located in wingtip nacelles to minimize the operational loads on the cross-shaft system and, with the rotors, tilt as a single unit.
  • the prop-rotors and their engines are used in the straight-up position where the thrust is directed downward.
  • the XV- 15 then climbs vertically into the air like a helicopter.
  • the problem of a failure of a gearbox, shaft, or rotor is not solved by this design.
  • the BA609, Bell-Agusta Tilt Rotor is the commercial offshoot of the Bell XV- 15, the tilt rotor proof of concept vehicle built at the main Bell plant in Hurst Texas and tested at the Arlington Texas facility.
  • the BA609 is still in development as of this writing and is not expected until about 2012.
  • this aircraft uses a cross- coupled drive shaft system in case of engine failure.
  • the problem of a failure of a gearbox, shaft, or rotor is not solved by this design.
  • the Bell/Boeing V22 Osprey Tilt Rotor is the military offshoot of the Bell XV-15 tilt-rotor. It uses two 6,150 HP engines and cruises at about 241kts. It was intended to lift 25 fully loaded combat troops and quickly carry them 500 miles to fight its way in and out of high threat landing zones. This vehicle represents a solution to Tilt Rotor flight, but has been quite costly in terms of development and unit cost.
  • the loss of a V22 in Arizona during a simulated mission is suspected to be due to asymmetrical Vortex Ring State (VRS). This is when one rotor effectively loses lift and the aircraft rolls and plunges to the ground.
  • VRS Vortex Ring State
  • the V22 utilizes cross coupled shafts, so that the failure of one engine allows the remaining engine to power the opposite rotor. This is complex, heavy and expensive. This may provide a solution for a single engine failure, but not a gearbox, bearing, rotor, or blade failure. This may be a reasonable risk to the military, compared to the lives it can save, but may prove problematic and too costly in the commercial market.
  • V22 Osprey The current technology twin tilt rotor V22 Osprey's recent performance is used as the best example of twin tilt rotor problems. Still, examination of the V22 performance data makes it clear that this is not a VTOL aircraft, but instead a STOVL aircraft.
  • the failure of either propulsion unit to produce thrust results in the loss of the aircraft and occupants.
  • the cross coupled drive shaft system provides a marginal performance backup limited to engine failure, not gearbox or rotor failures.
  • the installed weight of the cross-coupled drive shaft system reduces the all-important payload weight.
  • the loss of 50% of this aircraft's power results in its' inability to continue its' mission and in many circumstances requires immediate landing.
  • the present invention solves this problem with its' fundamental distributed propulsion design, providing for continued flight following the complete loss of thrust by any propulsion unit, no matter what the cause.
  • the present invention solves this problem by using much smaller diameter rigid propellers as opposed to helicopter like rotors which allow the blades to flap and distribute the load to six propellers instead of two rotors.
  • the propellers are smaller for the same disk loading, therefore they have a smaller moment of inertia.
  • Propellers have been used successfully on aerobatic airplanes and military dog fighters without blade separation due to these high gyroscopic forces.
  • the V22 Osprey has two rotors totaling a disk area of 2,268 square feet. Each blade is roughly 19 feet long (including hub radius), the length of a blade in a six propeller system of the same area would be eleven feet. This represents a significant reduction in blade root forces due to high G maneuvers. 3.
  • Limited center of gravity (e.g.) range The V22 design is inherently a narrow C.G. aircraft. The side by side location of the rotors does nothing to improve longitudinal e.g. range and the V22 has the highly limited e.g. range of a helicopter with a single rotor. It was intended that soldiers "down rope" from the left and right side of the V22, but the rotor wash blew them off the ropes due to the hurricane like wind below the rotors. A single rope was attached below the tail above the rear ramp area avoiding the rotor wash. This limited C.G. range prevents soldiers from moving to the rear ramp during "down roping" insertions, until the previous two have released the ropes' end at the ground.
  • the front rotor normally enters VRS first causing the front to drop, assisting in the necessary forward motion for recovery.
  • the V22 configuration is different.
  • the aircraft begins to roll, the pilot instinctively corrects with opposite stick, worsening the problem and the ship rolls over and plunges toward the ground. This is what possibly happened near Arlington, Arizona on a simulated night mission killing many Marines.
  • the present invention solves the VRS susceptibility problem for Tilt Propeller configurations by distributing the load among six propellers. When a propeller enters VRS the present invention should remain stable and controllable.
  • a vertical takeoff and landing aircraft comprising a fuselage, a plurality of wings attached to the fuselage, a first rotatable propulsion unit attached to a first side of each of the plurality of wings and a second rotatable propulsion unit attached to a second side of each of the plurality of wings.
  • Each rotatable propulsion unit comprises a propeller and a propeller hub.
  • each propeller comprises a plurality of blades, where each of the plurality of blades has a hole along its longitudinal axis.
  • Each propeller also comprise a plurality of rotatable rods, where each of the plurality of rods extends into the hole of a corresponding one of the plurality of blades.
  • each of the plurality of blades is enclosed in or adjacent to the propeller hub and rotatable around the corresponding one of the plurality of rotatable rods.
  • the distal end of each of the plurality of rods is fixed to a distal end of the corresponding one of the plurality of blades.
  • FIG. la and lb are top views of the aircraft with propulsion units in the horizontal and vertical positions;
  • FIG. 2a and 2b are side views of the aircraft with propulsion units in the horizontal and vertical positions;
  • FIG. 3a and 3b are front views of the aircraft with propulsion units in the horizontal and vertical positions;
  • FIG. 4 is a Flight Control Thrust Vectoring Mechanism
  • FIG. 5 is a cross-sectional view along the longitudinal axis of a propeller 80, in accordance with an exemplary embodiment of the present invention.
  • the invention is a vertical takeoff and landing aircraft.
  • this VTOL configuration is known as a tilt-prop aircraft, since the propellers are tilted forward for forward flight and tilted vertically for vertical flight.
  • this VTOL configuration is known as a tilt-rotor aircraft.
  • the propulsion units consist of engine driven fans this VTOL configuration is known as a tilt-fan aircraft.
  • Propulsion Unit refers to any method of producing thrust.
  • the example of an engine driven propeller is chosen solely for illustration purposes and is not intended to limit the scope of this invention.
  • the invention is valid for alternate means of propulsion including jet engines.
  • the propulsion units consist of jet engines this VTOL configuration is known as a "Tilt Jet” since the jets are tilted forward for forward flight and tilted vertically for vertical flight.
  • the invention is valid for alternate propulsion unit tilting implementations.
  • the engine may be mounted on the wing and transfer power through a gearbox into its tilt-able propeller or rotor. This design allows the engine or motor to remain relatively fixed in a single position without having to operate in multiple positions of the propeller.
  • the aircraft configuration consists of a conventional aircraft fuselage, with a nose, with or without pilot and/or co-pilot crew stations in the case of Unmanned Aerial Vehicle (UAV) applications, a central cabin or payload area, and a tapering empennage.
  • UAV Unmanned Aerial Vehicle
  • the aircraft has three wings, the front wing, middle wing, and the rear wing.
  • Two propulsion units are mounted above, below, or on each of the three wings, yielding six propulsion units.
  • the wings are fixed to the fuselage and the propulsion units rotate in unison to either of two (not including intermediate) positions, vertical or horizontal.
  • the propulsion units on opposite sides of the aircraft turn in opposite directions to cancel rotational moments about the yaw axis due to propeller or rotor torque.
  • Small flapped wing panels are fixed outboard of the forward and rearward propulsion units. These wing panels are located within the propulsion units' propeller slipstream. They provide yaw control during vertical flight. Their flaps are disabled in the neutral position once the propulsion units advance toward the horizontal position.
  • the main landing wheels are located at the rear end of the forward propulsion units.
  • a retractable and steerable tail wheel is located on the center line of the fuselage near the rear of the aircraft and retracts rearward and upwards into the normally unused space in the tail cone or alternatively for applications which require rear doors or a ramp the tail wheel may retract forward into the bottom of the fuselage.
  • the main wheels When the engines or motors rotate with the propellers or rotors the main wheels are mounted to the aft end of the forward propulsion unit engine support structures. This takes advantage of the existing structural load path which already exists for the engine support.
  • the main wheels may be attached to the aft end of the tilting assembly.
  • the propulsion units are spaced further apart than typical main gear designs increasing ground stability. Gear up landings are not possible with this invention as the landing gear is always down when the aircraft is in vertical flight mode. Separate landing gear controls and systems are not required. Proper placement of the main gear below the nacelle center line and clam shell gear doors can enable partial conventional takeoff and landings (CTOL) to enable additional payload capability when a runway is available. This is accomplished by placing the propulsion units in an intermediate position considering ground clearance is provided for the propeller, fan, or rotor tips. With jet propulsion units this would not be a problem.
  • CTL takeoff and landings
  • yaw control is accomplished by exhaust deflection or bleed air supplied attitude control nozzles, methods instead of the yaw control wing panel required in the tilt propeller embodiment.
  • the main landing gear consists of the same system described above except that the main wheels are not placed within the jet exhaust at the rear of the propulsion units but placed below the exhaust area.
  • the flapped front wing sometimes called a canard, and rear flapped wing operate differentially providing pitch control.
  • the aircraft contains a conventional vertical stabilizer and rudder assembly.
  • the rudder provides conventional yaw control during forward flight.
  • the middle wing contains conventional ailerons for roll control.
  • the crew station(s) When manned, the crew station(s) contain conventional helicopter controls, namely, a collective control used in vertical flight mode, a cyclic control for pitch and roll control, and rudder pedals for yaw control.
  • the forward wing is set at an effective angle of attack greater than the main and rear wing. This assures that this forward wing stalls first, dumping its load and causing a nose down pitching moment, for safety, restoring proper flight attitude, reducing the chance of the middle and rear wings stalling. Additional advantages of providing pitch control at the front and rear wing, as opposed to the single conventional rear elevator is the elimination of trim drag, the normal elevator down force and total elevator loss of control which can occur in deep stalls. Some aircraft have airfoils known as strakes, which are not required in this embodiment, mounted below their tails to provide a nose down pitching moment to prevent this from happening.
  • the rear wing may be mounted above the middle wing and the middle wing above the front wing. This arrangement reduces the exposure of each wing from flying in the downwash of the wing ahead of it, decreasing drag.
  • the wing spans of each wing are chosen to provide the design wing span and position each set of propulsion units such that the thrust wake of forward units do not disturb the propulsion units that are mounted to their rear.
  • the six propulsion units While in vertical flight, the six propulsion units are arranged around the aircraft producing thrust. Imagine a round table with six legs. Remove one leg and the table remains standing! The center of gravity of this aircraft is generally located about its' center. The propulsion units are placed such that the remaining thrust following the loss of thrust from one propulsion unit will maintain longitudinal and lateral static stability, therefore supporting the aircraft.
  • each propulsion unit contributes only 1/6 of the total thrust.
  • the twin tilt rotor V22 Osprey and BA609 engines must be sized such that one engine must supply the total power required for vertical flight. This means these engines need to be capable of greater than 200% of the normally required power.
  • the additional reserve power required of these engines represents a lot of extra pounds and dollars. They must carry this extra weight of the engines and drive shafts all the time which reduces their payload capacity. The owner or operator must pay the initial cost, and the continuing maintenance, and overhaul costs associated with this excess capacity. Also notice that the failure of a gearbox, rotor system or blade and asymmetrical VRS will result in the total loss of these aircraft.
  • the present invention requires its' propulsion units to have reserve power, to replace the thrust from the failed propulsion unit, but far less than previously discussed configurations. Much of this reserve power is already required for normal de-rating for reliability, aging, additional power for control, and additional power for vertical climbing and vertical decelerations. So, this distributed power invention requires little additional capacity due to a failed propulsion unit.
  • This invention solves the critical problem of failed engines, gearboxes, propellers, or rotors resulting in the loss of the aircraft and occupants.
  • This invention solves the problem of limited maneuverability of twin tilt rotor designs.
  • This invention solves the problem of limited center of gravity range of single or twin tilt prop/rotor designs.
  • This invention overcomes the susceptibility to Vortex Ring State of helicopters and twin tilt prop/rotor designs.
  • This invention solves the problem of propulsion redundancy requiring extra capacity and weight.
  • This invention solves the problem of a propulsion unit failure necessitating the eminent requirement to land.
  • This invention solves the problem of truly redundant VTOL flight combined with the speed, payload, and range similar to fixed wing aircraft.
  • This invention significantly reduces the retractable tricycle landing gear installed weight and complexity resulting in significantly increased payload capacity.
  • FIGS. 1 - 4 Shown in FIGS. 1 - 4 are a top view, a side view, a front view of the aircraft and a
  • Flight Control Thrust Vectoring Mechanism for a VTOL tilt-propulsion aircraft in accordance with the principles of the invention.
  • Large diameter tilt rotor propulsion units are best for relatively heavy lift and lower speed applications similar to the V22 Osprey due to their intrinsic lower disk loading, yielding higher lift efficiency and higher rotor drag during cruise.
  • the large blade areas of these rotors requires large power to drag them through the air at high speeds. Although these aircraft normally contain excess power allowing them to achieve high speed flight, the fuel consumed at these speeds significantly decreases range.
  • the V22 Osprey is capable of flight at 300kts, but recommended cruise is 241 kts.
  • Tilt propeller propulsion units are best for medium lift applications requiring relatively higher cruise speeds, similar to turboprop fixed wing aircraft, due to the propellers' lower weight and drag at higher cruise speeds. In contrast, tilt jet propulsion units are best for highest speed applications.
  • reciprocating engines are not so simple. Where cost and propulsive efficiency, for range, are important, reciprocating engines will be the best candidate. Where higher power, speed, and lighter weight become a driving factor, turbo-shaft engines will be the best candidate. The slightly lower reliability of modern reciprocating engines, relative to turbines, is no longer a factor in the present invention due to its redundancy. Small UAVs will use reciprocating engines. Other UAVs may use electric motors. When the UAV must carry ordinance or significant payload such as sensor weights exceeding 500 pounds, turbo- shaft engines may be indicated. Commercial market air ambulances will use turbo-shaft engines. The main variations of the invention involve this choice of engine size and propulsion technology.
  • FIGS 1 - 3 there is shown an aircraft 10 with six propulsion units 26 which can be in the vertical position for take off and landing and in the horizontal position for forward flight in accordance with the principles of the invention.
  • the tilt- prop aircraft here disclosed while not limited to any specific application, is intended to satisfy the medium weight and medium speed requirement.
  • the aircraft has three wings.
  • the rear wing 12 is mounted above the middle wing 14 which is mounted above the front wing 16.
  • the front wing 16 and rear wing 12 have differentially connected flaps 18 which provide the conventional forward flight pitch control.
  • the front wing 16 is set at a higher effective angle of attack which assures stall prior to the middle wing 14 and rear wing 12.
  • the middle wing 14 contains conventional ailerons 20 for roll control in forward flight.
  • the middle wing may extend beyond the propulsion units when a higher aspect ratio wing is required.
  • the aircraft has a conventional vertical stabilizer 22 and rudder assembly 24.
  • each wing half Located on each wing half is a propulsion unit 26 where the propulsion units of the aircraft of the FIGS, la through 3a are horizontally oriented and the propulsion units of the aircraft of FIGS, lb through 3b are vertically oriented.
  • Located outboard of the front and rear propulsion units 26 are yaw control panels 32 with flaps 30. They are fixed to the propulsion units and rotate with them providing yaw control during vertical flight.
  • the rear wing 12 with propulsion units 26 may be mounted at the top of the vertical stabilizer 22 as a traditional T-tail arrangement, mounted in the middle as a traditional cruciform arrangement, or at the bottom. Mounting the rear wing 12 at the bottom of the vertical stabilizer 22 may require a jog in the empennage, similar to the V22 empennage, to maintain the rear wing 12 mounting position above the middle wing 14.
  • the middle wing 14 may be located in the middle of the fuselage 28, allowing the rear wing 12 to be mounted on the upper surface at the base of the vertical stabilizer 22. This places the middle wing 14 spar in the cabin and may require an undesirable heavy ring carry through structure to prevent this.
  • a UAV may use this method without the ring structure.
  • Asymmetric thrust may be used for forward flight yaw control as long as the vertical stabilizer is sized for static lateral axis stability.
  • the engines' power should be approximately 150% of the power required for the "Hover Out of Ground Effect" H.O.G.E. hover and temperature requirements. This will provide for reliability de-rating, reduction of thrust due to engine aging, requirements for control power, and heave power (vertical acceleration and deceleration). This reserve generally should power match that necessary for engine-out operations.
  • Retractable landing gear either tired tricycle or retractable landing skids are indicted for the highest speed requirements.
  • Well faired fixed gear is appropriate up to about 200kts.
  • the gear should be designed for taxi capability and VTOL operations only.
  • the disclosed method of placing the main wheels at the aft end of the forward propulsion units will provide the lowest cost and greatest payload.
  • Blade tip speeds during hover should be about 800fps. Tip speeds during cruise should not exceed 0.8 Mach, except in tilt fan applications.
  • the propeller, gearbox, and engine combinations' static performance should be fully characterized and tested before the airframe detail design begins.
  • Power matching the cruise and hover requirement should be a design goal. When necessary, consider reducing the cruise speed requirement to meet this goal.
  • the rear wing should be mounted above the middle wing which should be mounted above the front wing to reduce drag due to downwash.
  • the front and rear wing should be flapped and differentially controlled to provide the conventional forward flight pitch control, and the front wing should be set at an effective angle of attack which assures stall prior to the middle and rear wings.
  • the middle wing should contain conventional ailerons for roll control in forward flight.
  • the aircraft should contain a conventional vertical stabilizer and rudder assembly.
  • the rear wing with propulsion units may be mounted at the top as a traditional T-tail arrangement, mounted in the middle as a traditional cruciform arrangement, or at the bottom. Mounting the rear wing at the bottom of the vertical stabilizer may require a jog in the empennage, similar to the V22 empennage, to maintain the rear wing mounting position above the main middle wing.
  • the main middle wing may be located in the middle of the fuselage, allowing the rear wing to be mounted on the upper surface at the base of the vertical stabilizer. This places the middle wing spar in the cabin or requires an undesirable heavy ring carry through structure.
  • Asymmetric thrust may be used for yaw control as long as the vertical stabilizer is sized for static lateral axis stability.
  • the aircraft should have a highly reliable and simple thrust vectoring control mixer.
  • the system should be analyzed carefully to eliminate single point failures causing total system failure. Failsafe thrust positions at the engines are necessary.
  • propulsion unit failsafe to some intermediate thrust by analyzing the hover power required at minimum useful load (single pilot and low fuel).
  • the aircraft design team should take advantage of the six alternators and batteries located within the propulsion units, to obtain a fail proof electrical power source for the avionics systems.
  • a minimum requirement is a left and right main electrical buss with a cross tie contactor.
  • the busses should be located on opposite sides of the aircraft.
  • each wing should have fuel bladders.
  • a single point fueling system is heavy and brings the fuel into the fuselage. This should only be considered in UAV or military application where it might be mandatory. For commercial applications it is not abnormal for four or more tanks to require filling.
  • the aircraft is controlled conventionally by helicopter type flight controls in forward flight.
  • the collective flight control is not used during forward flight.
  • Pitch and roll is controlled by the cyclic flight control which is differentially connected to the front and rear wing elevators for pitch control and middle wing ailerons for roll control.
  • the rudder pedals provide yaw control and are connected to the vertical stabilizer rudder.
  • the control of motion about the pitch and roll axis is by way of thrust vectoring, which is accomplished by reducing the propulsion units' thrust in the direction you want the vehicle to move toward and increasing the propulsion units' thrust opposite this direction.
  • This may be accomplished by a mechanical, electronic analog, digital or hybrid method, however, the following example is mechanical.
  • Thrust may be controlled by differentially controlling propeller pitch, engine RPM or many other methods.
  • a mechanism 50 which converts cyclic stick movement to thrust commands to six propulsion units.
  • This mechanism is used to control the propulsion unit's thrust resulting in the pitch and roll of the vehicle in vertical flight.
  • the mechanism is fundamentally a mechanical implementation of a rectangular (X, and Y) to polar (Displacement, and Angle)(Rho, Theta) coordinate converter, with the exception of an additional input, Z 68.
  • This Z input 68 causes an equal change in six displacement outputs 60. Therefore, there are three linear inputs, X 76, Y 64, and Z 68 and six displacement outputs 60.
  • the X input 76 be the pitch (fore or aft) position of the cyclic control
  • the Y input 64 be the roll (right or left) position of the cyclic control
  • the Z input 68 be the position of the collective (up or down) control.
  • the mechanism 50 consists of a central two piece vertical rod assembly, consisting of two coaxially oriented rod pieces 52, 54, one above the other, with a universal joint 56 connected between them.
  • the bottom vertical rod segment 54 is mounted in a fixed position linear bearing 66 near its bottom end, allowing vertical movement of the rod assembly which consists of 52,54,56,58,60,62,64,68,70,74, and 76.
  • a disk 74 is fixed on rod 54 above linear bearing 66 and below universal joint 56. Attached to the periphery of disk 74 is the Z axis input fitting 68. This is the Z axis, or collective input to the mechanism. When you raise or lower the collective control the rod assembly rises and falls in unison.
  • Disk 74 contains a vertically oriented fixed linear bearing 70 with a small fixed vertical rod 72 passing through it. This prevents the rod assembly 52,54,56,58,60,62,64,68,70,74, and 76 from rotating.
  • a disk 58 is mounted on the upper rod 52 segment midway between the universal joint 56 and top end. There are six attachment points 60 around disk 58 which correspond to the relative angular locations of the propulsion units on the aircraft. These six attachment points 60 are the six thrust command outputs of the mechanism.
  • a similar disk 62 is attached to the top of the upper rod segment. This disk has two orthogonally oriented attachment points 64 and 76 on the disk. These are the X 76 or pitch, and Y 64 or roll inputs. The cyclic control is connected to these two inputs, X 76 or pitch, and Y 64 or roll, and the top of the vertical rod 52 mimics the cyclic control position.
  • the disk 62 at the top of the mechanism 50 moves forward and to the right since the disk 62 is connected to the cyclic control by way of the Pitch "X" 76 and Roll “Y” 64 inputs.
  • the centrally located thrust command disk 58 mounted above the universal joint 56 moves with the rod 52 in the same direction, 45 degrees to the right.
  • the thrust command attachment points 60 also move because they are part of the disk. Assuming the use of propeller pitch control cables, the thrust outputs 60 from the disk 58 push (reducing pitch and therefore thrust) on the cables in the direction of the desired vehicle movement and pull (increasing pitch and therefore thrust) on thrust cables in the opposite direction in an amount proportional to their relative angular placements.
  • Raising the collective flight control causes the rod assembly 52,54,56,58,60,62,64,68,70,74, and 76 to rise and therefore pulls on all thrust cables equally, increasing the propeller pitch and therefore thrust on all six propulsion units equally.
  • Yaw control is provided through rudder pedals, controlling the flapped outboard wing panels.
  • the conventional rudder remains connected and moves with the rudder pedals during hovering flight.
  • Roll and pitch control by thrust modulation remains active until the propulsion units are commanded to leave the vertical position.
  • the front and rear wing pitch control flaps and middle wing ailerons remain connected to the cyclic flight control during hovering flight.
  • the front, middle, and rear wing flaps may be placed in a down position to reduce the vertical drag on the wing caused by the high velocity propeller wakes. These flaps must return to normal forward flight operation prior to disabling thrust vectoring control.
  • the aircraft is brought to a hover and systems are checked similar to helicopter procedures. Once final checks are complete and cleared, the aircraft is accelerated to a transition speed. At this speed, the Middle wing Ailerons, Rudder, Front and Rear Wing flaps are fully effective for aircraft control.
  • a conversion switch is placed in the first forward position causing the propulsion units to move to an intermediate forward position. The aircraft will accelerate to a specified forward speed when the conversion switch is then placed in the second intermediate forward position which causes the propulsion units to rotate to the second intermediate position and the wing panel flaps providing the yaw control during hover to return to the neutral position. Once the aircraft accelerates to a new specified speed, the conversion switch is placed in the forward flight position, the propulsion units rotate to the forward flight position and the conversion process is complete. The propulsion units' angular rate from hover to forward flight position should be approximately 6 degrees per second.
  • each blade station i.e., each point along the length of a propeller blade
  • the blade angle though fixed at any given station along the length of the blade, progressively changes from a first predetermined blade angle adjacent the hub to a second predetermined blade angle at the distal tip of the blade.
  • This blade angle distribution typically involves the blade root chord approaching the axis of the shaft which the propeller is mounted on. While this is optimal for the one forward speed, is not optimal for static thrust. If applied to a static thrust producer, much of the blade root would be stalled. Hence, helicopter rotor blades are sometimes twisted, but at a fraction of the twist of propeller blades.
  • FIG. 5 is a cross-sectional view along the longitudinal axis of a propeller 80, in accordance with an exemplary embodiment of the present invention, which overcomes the aforementioned problems of the prior art propeller technology.
  • propeller 80 comprises a blade 82.
  • blade 82 is made of composite material, such as carbon graphite, wherein the fibers are arranged such that blade 82 is flexible (i.e., twistable) about its longitudinal axis while resisting forces parallel to the propeller spinning axis.
  • a rod or tube 84 e.g., a steel rod
  • the rod 84 may extend into the distal tip of blade 82, as shown, where it is anchored (fixed) to blade 82.
  • the distal tip of rod 84 is bonded to blade 84 at or near the distal tip of blade 84.
  • the rod 84 may extend in the opposite direction into the propeller hub (not shown), where a cam 86 is attached to rod 84.
  • a first actuator (not shown) may drive a first cam 86 which would apply a torsional force to rod 84, thus causing rod 84 to rotate. It will be understood that at least the distal tip of blade 82 would also rotate with rod 84 as the two are fixed to each other as explained.
  • the root of blade 82 may be circular in cross section and comprise one or more blade retention structures 88.
  • the root of blade 82, including the blade retention structures 88 are, at least in part, mounted within an adjustable pitch blade retention mechanism.
  • the adjustable pitch change mechanism would include a second actuator (not shown), such as a small electric motor mounted coaxially with the propeller.
  • the second actuator may drive a second cam (not shown) that, in turn, may impart a force on a pin 90, positioned at the root of blade 82, as shown.
  • the force acting on pin 90 would cause the root of blade 82 to twist around the rod 84.
  • the angle associated with the distal tip of blade 82 angle may remain unchanged, as it is restrained by the fact that it is fixed to the rod 84.
  • the blade twist technique is similar to the technique associated with propellers produced by IVO props.
  • the blade root is fixed to the propeller hub and the torsion tube or rod is anchored to the blade tip.
  • the twisting of the blade is accomplished by rotating the torsion tube or rod within the hub using a small cam, driven by a electric motor driven leadscrew.
  • the propeller blade angle at the hub is fixed and not adjustable, as in the present design.
  • the present design is optimal, because in the present design, the pitch angle associated with the distal tip of blade 82 is adjustable independent of the angle associated with the root of blade 82, and the root of blade 82 is adjustable independent of the angle associated with the distal tip of blade 82. Accordingly, the pitch angle distribution of blade 82 can be adjusted and, therefore, optimized to achieve effective static thrust and high speed forward flight.
  • the engine size of any version of this aircraft is significantly smaller than competitive configurations. Smaller engines tend to be simpler to handle and maintain. The design of most aircraft is limited to existing engine designs. It is rare that a new power plant is designed and manufactured for a new aircraft. An aircraft which utilizes relatively smaller engines has a much larger quantity to select from (smaller engines types are more numerous than high horse power engines). Smaller engines can be less expensive per horsepower than larger engines. The higher quantity of six engines allows more economies of scale to be realized. A manufacturer is far more interested if the aircraft utilizes six engines as opposed to one or two per vehicle. Quantity discounts are far more likely in this situation.
  • the embodiment of this invention places six propulsion units in approximately equal angular distributions around the aircraft. This unique placement provides for the continued flight following a single propulsion unit failure.
  • the aircraft center of gravity is designed to be located along the center line of the fuselage and approximately near the center of the middle wing spar.
  • the propulsion units are designed to have reserve power in the event of an engine propulsion unit failure. So, inherent safety following a propulsion unit failure without any special pilot talent or proficiency is a unique characteristic of this invention.
  • Locating the fuel tanks within the propulsion units places the fuel away from the cabin occupants. Thus, fire in the cabin during flight or crash is unlikely.
  • the forward wing stall behavior reduces the likelihood of the middle or rear wing stalling, reducing stall related accidents.
  • Locating the main wheels at the aft end of the forward propulsion units widens the space between the traditional main gear, increasing ground lateral stability.
  • the rear wing of this configuration supports its share of the vehicle weight as opposed to conventional aircraft.
  • Conventional aircraft normally use a less efficient un- cambered airfoil known as the horizontal stabilizer.
  • the stabilizer operates with a downward force during normal flight. This force effectively adds additional weight reducing payload capability. It also creates drag due to this negative lift, known as "trim drag”.
  • trim drag due to this negative lift, known as "trim drag”.
  • the V22 Osprey uses a conventional horizontal stabilizer and elevator in its configuration.
  • the supersonic Concord actually pumped fuel to a tank in its tail to reduce this trim drag.
  • the front wing is a cambered airfoil wing which operates as a lift producer and at the same time provides pitch control as a canard with elevator. So, rather than paying for the weight, trim drag, and negative lift of the horizontal stabilizer.
  • the rear wing becomes part of the lift producing wing function as well as sharing pitch control with the front wing.
  • the location of the propulsion units near the wing ends can provide an end plate effect which reduces the normal magnitude of wing tip vortices and improving span efficiency factor, reducing induced drag and, therefore, increasing range.
  • a structural efficiency can be gained by distributing propulsion unit weight near the wing tips which reduces wing root bending loads and, therefore, wing weight.
  • propulsion units avoids the weight, complexity, and cost of a cross coupled engine drive shaft system.

Abstract

Avion à décollage et atterrissage verticaux comportant un fuselage avec, de préférence, trois ailes et six unités de propulsion inclinables synchroniquement, chacune étant montée au dessus, en dessous ou sur chaque moitié des trois ailes susmentionnées. Les unités de propulsion sont orientées verticalement pour un vol vertical et horizontalement pour un vol vers l'avant. Chaque unité de propulsion comprend une hélice comportant une pluralité de pales, où les angles de pas associés à l'extrémité distale de chaque pale et à l'extrémité proximale de chaque pale sont réglables indépendamment. À ce titre, on peut régler chacune des hélices pour offrir une première répartition d'angles de pas de pale optimisée pour le vol vertical et une seconde répartition d'angles de pas de pale optimisée pour le vol vers l'avant.
EP11831080.4A 2010-10-08 2011-06-27 Avion adav à trois ailes et six unités de propulsion inclinables Withdrawn EP2625094A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US12/900,790 US8616492B2 (en) 2009-10-09 2010-10-08 Three wing, six tilt-propulsion units, VTOL aircraft
PCT/US2011/040693 WO2012047327A1 (fr) 2010-10-08 2011-06-16 Avion vtol à trois ailes et six propulseurs basculants
US13/168,624 US8708273B2 (en) 2009-10-09 2011-06-24 Three-wing, six tilt-propulsion unit, VTOL aircraft
PCT/US2011/041975 WO2012047337A1 (fr) 2010-10-08 2011-06-27 Avion adav à trois ailes et six unités de propulsion inclinables

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EP2625094A1 true EP2625094A1 (fr) 2013-08-14

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US10625852B2 (en) * 2014-03-18 2020-04-21 Joby Aero, Inc. Aerodynamically efficient lightweight vertical take-off and landing aircraft with pivoting rotors and stowing rotor blades
CN112623264A (zh) * 2019-10-08 2021-04-09 灵翼飞航（天津）科技有限公司 一种无人机机载动态测试系统
EP4143087A1 (fr) * 2020-04-30 2023-03-08 Volansi, Inc. Aéronef à décollage et atterrissage verticaux fixe modulaire avec unités remplaçables en ligne
US11208206B1 (en) * 2021-05-17 2021-12-28 Beta Air, Llc Aircraft for fixed pitch lift
CN116558766B (zh) * 2023-07-10 2023-09-01 中国空气动力研究与发展中心低速空气动力研究所 一种气动干扰环境下尾桨气动特性试验地面模拟方法

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