CONTROLLED CIRCULATION STOWABLE ROTOR FOR V/STOL AIRCRAFT

• US 3,612,444 A
• Filed: 11/10/1969
• Issued: 10/12/1971
• Est. Priority Date: 11/10/1969
• Status: Expired due to Term

• Current Assignee: Peter F. Girard
• Original Assignee: Peter F. Girard
• Inventors: Girard, Peter F.
• Primary Examiner(s): Buchler, Milton
• Assistant Examiner(s): Rutledge, C. A.
• Application Number:
  US04/875,226
• Time in Patent Office: 701 Days
• Field of Search: 244/7,42,41,65,49 416/90,142,20
• US Class Current: 244/7.00A
• CPC Class Codes: B64C 27/30 with provision for reducing drag of inoperative rotor

Abstract

A stoppable helicopter-type rotor is provided with means to blow air angularly outward toward the leading and trailing edges, above and below each rotor blade. The rotor includes means to stop and fold the blades and stow the folded structure in an enclosure in an aircraft, the air blowing being used during transition between vertical and horizontal flight modes to spoil the lifting effect of the blades during stopping of rotation of the rotor and so eliminate the blade-bending loads which are a major problem with stoppable rotors.

Claims

1. In an aircraft having fixed lifting surfaces and forward flight propulsion means, a selectively driven rotor mounted on the aircraft and having at least one lifting blade, substantially spanwise air-conducting passage means in said blade, a plurality of spanwise spaced outlet holes in said blade communicating with said passage and extending angularly outwardly through at least the upper surface of the blade adjacent the leading and trailing edges thereof, to direct air angularly across the normal flow over the blade and spoil the lift thereof, and means for connecting said passage to a source of compressed air.

2. An aircraft according to claim 1 and including a further plurality of spanwise spaced outlet holes communicating with said passage means and extending angularly outwardly through the lower surface of the blade adjacent and toward the leading and trailing edges thereof, respectively, to direct lift spoiling flow outwardly from the blade.

3. An aircraft according to claim 2 and including valve means in said air-conducting passage means, selectively operable to open and close said outlet holes.

4. An aircraft according to claim 3 and including actuating means connected to said valve means, said actuating means being responsive to an increased air pressure in said passage means to open said outlet holes.

5. In an aircraft having fixed lifting surfaces and forward flight propulsion means, a selectively driven rotor mounted on the aircraft, said rotor having a head with a plurality of lifting blades thereon, certain of said blades being hinged on said head to swing substantially in the plane of the rotor into a generally parallel compact group of blades, mounting means securing said rotor to the aircraft, said mounting means being foldable to retract the rotor into the aircraft, each of said blades having lift spoiling means therein, and means to actuate the lift-spoiling means during transition between vertical and horizontal flight.

6. An aircraft according to claim 5, wherein said lift-spoiling means comprises a plurality of spanwise spaced outlet holes opening angularly outwardly from the blade adjacent and toward the leading and trailing edges thereof in at least the upper surface of the blade, and a source of compressed air communicating with said outlet holes.

7. An aircraft according to claim 6, wherein said outlet holes are in the upper and lower surfaces of the blade.

8. An aircraft according to claim 5, wherein said lift-spoiling means comprises a plurality of spanwise spaced outlet holes opening angularly outwardly and forwardly from the upper surface of the blade adjacent the leading edge thereof, a plurality of spanwise spaced outlet holes opening angularly outwardly and rearwardly from the upper surface of the blade adjacent the trailing edge thereof, air conducting passages in said blade communicating with said outer holes, and a source of compressed air connected to said passages.

9. An aircraft according to claim 9 and including valve means in said passages for selective opening and closing of said outlet holes.

10. An aircraft according to claim 9 and including air pressure responsive actuating means connected to said valve means to open said outlet holes upon a predetermined increase in air pressure in said passages.

11. An aircraft according to claim 10, wherein said actuating means is biased to move said valve means to the closed position of said outlet holes when air pressure in said passages is below a predetermined pressure.

12. An aircraft according to claim 8 and including a further plurality of spanwise spaced outlet holes opening angularly outwardly and forwardly from the lower surface of the blade adjacent the leading edge thereof.

13. An aircraft according to claim 12 and including a further plurality of spanwise spaced holes and opening angularly outwardly and rearwardly from the lower surface of the blade adjacent the trailing edge thereof.

14. An aircraft according to claim 13, wherein said air-conducting passages comprise a substantially cylindrical spanwise passage in the leading edge portion of the blade communicating with the upper and lower surface outlet holes therein, and a substantially cylindrical spanwise passage in the trailing edge portion of the blade communicating with the upper and lower surface outlet holes therein.

15. An aircraft according to claim 14 and including valve means comprising sleeve valves axially rotatable in said passages and having ports registrable with said outlet holes in one position of the valves.

16. An aircraft according to claim 15 and including air pressure responsive actuating means connected to said sleeve valves to rotate the sleeve valves simultaneously and open said outlet holes upon a predetermined increase in air pressure in said passages.