Aeronautics and astronautics – Aircraft – heavier-than-air – Airplane and auto-rotating wing sustained
Reexamination Certificate
1999-07-15
2002-10-29
Poon, Peter M. (Department: 3643)
Aeronautics and astronautics
Aircraft, heavier-than-air
Airplane and auto-rotating wing sustained
Reexamination Certificate
active
06471158
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to vertical take-off and landing aircraft and, more particularly, to an improved vertical take-off and landing aircraft featuring a turbofan powered, compound autogyro with retractable rotor blades and vectored thrust.
BACKGROUND OF THE INVENTION
World runway congestion is an acute and growing problem evoking costly delays for both air carriers and passengers. This serious situation is forecast to go critical in the early years of the next century. By the year 2016, for instance, all forecasts indicate that global enplanements will triple over 1990 levels but runways will not keep pace.
While there will be some new runways and airports built in the future, plus an improved management of air space, major markets such as New York, Chicago, Frankfurt and London will not experience a sufficient enhancement of runway capacity. Aircraft noise and other environmental concerns form the chief restrictions to airport development. But pervasive land use and high costs are also factors.
Clearly, there is an urgent need for a large, safe, vertical take-off and landing vehicle (VTOL) operating off Verti-pads at major airports. These VTOL operations, mostly on short haul service, would help free up runways for conventional jets.
The unique design of the VTOL aircraft of this invention addresses the congestion problem, and is useful as a vehicle for humanitarian and disaster relief. It can also find applicability in timbering, fire fighting, defense employment and delivering social services to remote regions of the Third World.
The new aircraft of this invention is believed to be capable of changing many aspects of the aviation industry. While the design incorporates most of the attributes of a helicopter, the aircraft operates on the autogyro principle. Independent lift and propulsion systems are incorporated in the aircraft in a manner known in the trade as a compound autogyro, sometimes referred to as a converti-plane.
Designers, since 1946, have attempted to combine the best qualities of the airplane and the helicopter, while avoiding the limitations that each aircraft presents. The “ROTODYNE” was a compound autogyro invented in England, and was successfully demonstrated on test routes in Europe. It proved that it was indeed possible to design a safe VTOL airliner capable of lifting 70 passengers.
Alongside this development, the tilt rotor VTOL became popular in the United States. The tilt rotor, however, was not the answer for civil operations, owing to the fact that it was sized improperly. It was also troubled by a series of fatal accidents. The tilt rotor VTOL was limited to about 40 passengers, far too limited to achieve a profitable seat mile rate. Additionally, the tilt rotor was propulsion restricted to the available turboprop engines, or a cruise speed of about 340 mph, too slow to meet the 21st Century air carrier demands, even on short stage length routes.
Common misconceptions with respect to vertical lift aircraft have been widely held in the industry. Despite the existence of the ROTODYNE aircraft, the air carrier industry seems to doubt that a safe, fast, comfortable, 145-seat VTOL commercial airliner can be designed. Many mistakenly believe that such aircraft cannot be designed with backups such as two and three hydraulic systems, redundant pumping, two electrical systems, etc., which are common on conventional jet transports. Another misconception with respect to VTOL aircraft has been that turbofans could not be employed, or were somehow incompatible with rotary-winged aircraft.
A workable VTOL of this invention uses proven and demonstrated technology, and is commercially practical.
The inventive VTOL has an operating envelope between hover, or zero mph, and 520 mph. It can also stop in mid air, and back up by reversing the flow of the turbofan's exhaust.
The VTOL airliner of this invention is an assembly of proven systems designed to provide a comfort zone for air carriers and passengers alike.
The VTOL airliner of the invention operates as a conventional airliner, employing its blade system only when entering terminal air space on take-offs or landings.
The VTOL of this invention, above all else, is safe. The inventive VTOL airliner is designed with fail-safe and redundant systems, such as those featured on conventional commercial aircraft.
In the preferred embodiment of this invention, the VTOL aircraft features two independent power systems. One set of augmented turbofans, proven military engines, are employed to power the rotor blades via a reactive drive system known in the industry as the hot cycle which eliminates the need for a tail rotor and complicated reduction gearing.
Another set of engines, known in the industry as high by-pass turbofans, are employed for the cruise portion of the flight, while the augmented turbo fans are taken off line.
The inventive aircraft has a retractable rotor. Should the rotor system fail to descend into the fuselage when a retraction command is given, the rotor will simply windmill. Should the rotor system fail to pump up for a landing, then the landing can be accomplished via conventional fixed wing and rear thrust options. These options make the VTOL of this invention extremely safe and reliable. The duality of lift and propulsion, plus the available emergency downthrust, provides a safety net for a mechanical or structural failure, or when operating in areas of critical icing and “downbursts.”
Another advantage of the invention is its seating design. Airliners such as the 737, 757, etc., called narrow bodies, can arrange first class or business class seating only at four abreast. The 737-300 series has a fuselage transverse section of 139 inches. In comparison, the present invention can achieve first class seating with six abreast, by adding 32 inches on the breadth of the fuselage, for a total of 171 inches. This allows the carrier to offer 96 high priced seats to business travelers. The simple design change also offers a three and four offset aisle arrangement comprising 150 coach class seats, plus a twin aisle layout for six abreast seating. An additional advantage of this aircraft is its ability to operate in a fully competitive regime as a fixed wing, conventional jet without employing the rotor mast. This design element should increase the vehicle's service flexibility.
DISCUSSION OF RELATED ART
Typically, in a vertical lift vehicle such as a helicopter, forward speed is limited due to the onset of compressibility in the retreating region of the blade path. Realizing this constraint, designers have attempted to combine the strongest flight mechanics of the helicopter and the fixed wing aircraft.
One such design is that of the tilt rotor, whereby the engines are faced upward for take-off and then tilt downward for conventional cruise flight. However, current turboprop engines employed by the tilt rotor do not have sufficient horsepower to lift a vehicle large enough to carry a sufficient payload for commercial and humanitarian purposes.
Another scheme for combining the qualities of the helicopter and the conventional aircraft is disclosed in U.S. Pat. No. 3,986,686. This vehicle features a four-bladed rotor in the “X” configuration which houses two blades against the airframe, while the two other airfoils form a fixed wing. This design, however, stops the rotary wing in flight, in order to convert this airfoil into a fixed wing. This is clearly unacceptable for high load, cargo and passenger operations. Computational fluid dynamic models have indicated that during the transition from rotary wing to fixed wing flight, oscillations, vibrations and instability problems arise. Additionally, the geometry, wing loading, high lift devices of a fixed wing are inconsistent with the attributes of a rotary wing. The compromise between the two airfoils, even if the transitional problems could be solved, would result in a high drag vehicle with L/D (lift over drag) ratios around ten or less. A modern airliner operates with L/D values of about 15, which is both fuel effici
Jakel Kevin
Poon Peter M.
Salzman & Levy
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