QUIET SLAT PROPELLER
A propeller for an aircraft having a fuselage and a pair of fixed wings includes a mounting member secured to at least one wing. At least one blade is rotatably connected to each mounting member and has an airfoil shape. The at least one blade is in a locked condition during take-off and landing of the aircraft extending parallel to a leading edge of the wing and in an unlocked, rotating condition during flight for propelling the aircraft.
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The present invention relates to aircraft and, in particular, relates to an aircraft having propeller blades that act as Handley-Page slats during take-off and landing.
BACKGROUND OF THE INVENTIONSome conventional aircraft, such as fixed wing planes, have leading edge flaps or slats, known as Handley-Page slats, to improve the airflow around and across the fixed wings during take-offs and landings. These flaps/slats add weight to the aircraft and increase the complexity of the wings. Furthermore, the slats and must be carefully stowed in the wings for cruise flight to avoid drag while being capable of extension into the airflow during take-off and landing. Some aircraft, such as the V-22 Osprey, have large propellers and avoid ground clearance issues by tilting the heavy engines and propellers. No improvement to the airfoil shape across the wing, however, is obtained by this tilting design.
SUMMARY OF THE INVENTIONIn accordance with an embodiment of the present invention a propeller for an aircraft having a fuselage and a pair of fixed wings includes a mounting member secured to at least one wing. At least one blade is rotatably connected to each mounting member and has an airfoil shape. The at least one blade is in a locked condition during take-off and landing of the aircraft extending parallel to a leading edge of the wing and in an unlocked, rotating condition during flight for propelling the aircraft.
In accordance with another embodiment of the present invention an aircraft includes a fuselage extending along a centerline from a first end to a second end. A pair of fixed wings extends outwardly from the fuselage. A cross-section of each wing defines an airfoil having a leading edge extending perpendicular to the centerline. A tail is secured to the second end of the fuselage. A first propeller is secured to the first end of the fuselage and is rotatable for propelling the aircraft. A pair of second propellers is secured to the wings. Each second propeller includes a mounting member for securing the second propeller to each wing and at least one blade rotatably connected to the mounting member. Each blade has a locked condition during take-off and landing of the aircraft extending parallel to the leading edge of the respective wing and an unlocked, rotating condition during flight for propelling the aircraft.
In accordance with another embodiment of the present invention a propeller for an aircraft includes a mounting member that secures the propeller to the aircraft. At least one blade is rotatably connected to the mounting member and has an airfoil shape. Each blade has a locked condition during take-off and landing of aircraft extending parallel to an edge of the aircraft and an unlocked, rotating condition during flight for propelling the aircraft.
Other objects and advantages and a fuller understanding of the invention will be had from the following detailed description and the accompanying drawings.
The present invention relates to an aircraft and, in particular, relates to an aircraft having propeller blades that act as Handley-Page slats during take-off and landing.
A pair of fixed wings 50a, 50b extends from the fuselage 22 between the first and second ends 26, 28 on opposite sides of the centerline 24. The wings 50a, 50b extend substantially perpendicular to the centerline 24 and are larger than the wings 44a, 44b on the tail assembly 40. Each wing 50a, 50b includes an end 54 spaced from the fuselage 22. Referring to
A propeller 70 is secured to each end 54 of the fixed wings 50a, 50b. Each propeller 70 includes one or more blades 72 and a mounting member 76 secured to or integrally formed with the end 54 of the wing 50a, 50b. The mounting member 76 extends parallel to the centerline 24. Although
Referring to
Referring to
Once the aircraft 20 is in flight, the locking mechanisms release the propellers 70 to allow the motors to rotate the blades 72 in the respective directions R1, R2 to provide additional thrust to the aircraft in the direction T. When landing is desired, the propellers 70 are again locked in place by the locking mechanism to place the leading edges 80 of the blades 72 in position extending parallel to the leading edges 58 of the wings 50a, 50b. The propeller 32 keeps rotating while the propellers 70 are locked to maintain thrust T to the aircraft 20 and, thus, the propeller 32 provides the only thrust to the aircraft 20 during landing.
The propellers 70 of the present invention are advantageous in that some of the blades 72 act as Handley-Page slats for take-off and landing of the aircraft 20. In particular, during take-off and landing of the aircraft 20, locking the blades 72 positions some of the blades directly upstream of the leading end 58 of the respective wing 50a, 50b. More specifically, the inner blades 72 closer to the fuselage 22 are positioned adjacent the leading ends 58 of the wings 50a, 50b. The outer blades 72 extend beyond the ends 54 of the wings 50a, 50b. Due to the airfoil shape and positioning of the inner blades 72, the incoming airstream A flowing towards the leading end 80 of the blade 72 is guided towards and over the top of the respective wing 50a, 50b by the inner blades (see
Since the stationary inner blades 72 function as Handley-Page slats during take-off and landing of the aircraft 20, there is no need for conventional slats that must be mechanically retracted and extended during take-off and landing. Moreover, providing two blades 72 per propeller 70 allows the blades to rotate R1, R2 at slower speeds, which reduces the noise of the propellers over conventional propellers. Aircraft propeller noise is directly related to propeller speed. One way to reduce propeller speed is to have larger propellers that rotate slower. The diameter of the propellers, however, are normally limited by ground clearance, rail launch clearance, and other physical impediments. By storing the blades 72 of the present invention in the plane of the wings 50a, 50b during take-off and landing the present invention advantageously eliminates these clearance issues. The dual purpose blades 72 of the present invention therefore advantageously simplify assembly and operation of the aircraft 20 while reducing the noise output thereof.
The aircraft 120 of
The outer blades 272, on the other hand, are pivotably mounted to the mounting member 76 via hinges 280. As shown in
Prior to flight, e.g., in storage, the inner blades 72 of each propeller 270 are locked in the position extending parallel to the respective wing 50a, 50b and towards the centerline 24. The outer blades 272 are placed in the stowed first position to minimize the space needed to store and transport the aircraft 220. In anticipation of flight, the outer blades 272 are pivoted in the respective directions R3, R4 into the extended second positions, locked in place in longitudinal alignment with the already locked inner blades 72. Each inner blade 72 of the aircraft 220, when locked in place during take-off and landing, acts as a Handley-Page flap in a manner similar to the inner blades 72 of the aircrafts 20, 120. During flight, the blades 72, 272 are unlocked and are counter-rotative, with the blades 72, 272 on the wing 50a rotating in the clockwise direction R1 and the blades on the wing 50b rotating in the counterclockwise direction R2 to produce additional thrust to the aircraft 220 in the direction T.
The aircraft 220 of
The propellers 70, 170, 270 of the present invention can be used on any sized aircraft, whether manned or unmanned For example, the propellers 70, 170, 270 can be employed on novelty aircraft, drones (surveillance or combat), other military aircraft, and private and low altitude aircraft, among others. The propellers 70, 170, 270 are advantageous where short take-off and landing is either desirable or the only feasible scenario, e.g., aircraft carriers, military bases, hostile environments, etc. The propellers 70, 170, 270, in combination with the propeller 32, help provide aircraft that are more fuel efficient (cheaper), quieter, and better over long distances than jet engine aircraft.
Additionally, the stowed large wing tip propellers 70, 170, 270 of the present invention improve low speed wing performance, thereby allowing shorter take-offs and landings or higher weight aircraft for a given size. The present invention eliminates leading edge flaps and slats, which simplifies the wing design and improves wing airfoil shape, including the potential for laminar flow. Rotating large wing tip propellers during climb, cruise, and descent also reduce propeller vortex noise by reducing the propeller rotation speed. Vortex noise is a function of propeller velocity to the 6th power and, thus, the reduced propeller 70, 170, 270 speed of the present invention allows for dramatic noise reduction.
A guide wire 330 is connected to the kite 320 and tethers the kite to the ground 400. The guide wire 330 includes a pair of first portions 340a connected to the side edges 306, 308 and a second portion 340b connecting the first portions to the ground 400.
A pair of propellers is secured to the top edge 302 of the kite 220 by mounting members 310. Each propeller can be any of the aforementioned and described propellers 70, 170, 270. As shown, each propeller constitutes the propeller 70 of
What have been described above are examples of the present invention. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the present invention, but one of ordinary skill in the art will recognize that many further combinations and permutations of the present invention are possible. Accordingly, the present invention is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims.
Claims
1. A propeller for an aircraft having a fuselage and a pair of fixed wings comprising:
- a mounting member secured to at least one wing; and
- at least one blade rotatably connected to each mounting member and having an airfoil shape, the at least one blade having a locked condition during take-off and landing of the aircraft extending parallel to a leading edge of the wing and an unlocked, rotating condition during flight for propelling the aircraft.
2. The aircraft recited in claim 1, wherein the propeller includes only one blade.
3. The aircraft recited in claim 2, wherein the blade extends towards the fuselage and parallel to the wing when in the locked condition.
4. The aircraft recited in claim 1, wherein the at least one blade comprises a pair of blades.
5. The aircraft recited in claim 4, wherein one of the pair of blades is pivotable about a hinge between a first condition extending perpendicular to the wing and a second condition extending parallel to the wing and longitudinally aligned with the other of the pair of blades.
6. The aircraft recited in claim 1, wherein the airfoil shape of the blade has a leading edge extending parallel to a leading edge of the wing when in the locked condition and a trailing edge.
7. The aircraft recited in claim 1, wherein a mounting member is secured to each wing, the at least one blade on each mounting member extending towards one another and being longitudinally aligned with one another when in the locked condition.
8. The aircraft recited in claim 7, wherein the at least one blade comprises a pair of blades, all the blades being longitudinally aligned with one another when in the locked condition.
9. The aircraft recited in claim 8, wherein one of each pair of blades is pivotable about a hinge between a first condition extending perpendicular to the wing and a second condition extending parallel to the wing and longitudinally aligned with the other of the pair of blades.
10. The aircraft recited in claim 7, wherein the at least one blade on each mounting member rotates in opposite directions from one another.
11. The aircraft recited in claim 1, wherein each blade is locked to direct air onto the wing to provide lift to the aircraft.
12. An aircraft comprising:
- a fuselage extending along a centerline from a first end to a second end;
- a pair of fixed wings extending outwardly from the fuselage, a cross-section of each wing defining an airfoil having a leading edge extending perpendicular to the centerline;
- a tail secured to the second end of the fuselage;
- a first propeller secured to the first end of the fuselage and being rotatable for propelling the aircraft; and
- a pair of second propellers secured to the wings, each second propeller including a mounting member for securing the second propeller to each wing and at least one blade rotatably connected to the mounting member, each blade having a locked condition during take-off and landing of the aircraft extending parallel to the leading edge of the respective wing and an unlocked, rotating condition during flight for propelling the aircraft.
13. The aircraft recited in claim 12, wherein each second propeller includes only one blade.
14. The aircraft recited in claim 13, wherein each blade extends from the mounting member towards the fuselage and parallel to the wing when in the locked condition.
15. The aircraft recited in claim 12, wherein the at least one blade comprises a pair of blades.
16. The aircraft recited in claim 15, wherein one of each pair of blades is pivotable about a hinge between a first condition extending perpendicular to the wing and a second condition extending parallel to the wing and longitudinally aligned with the other of the pair of blades.
17. The aircraft recited in claim 12, wherein the airfoil shape of each blade has a leading edge extending parallel to the leading edge of the wing when in the locked condition and a trailing edge spaced from the wing.
18. The aircraft recited in claim 12, wherein each blade is locked to direct air onto the wing to provide lift to the aircraft.
19. A propeller for an aircraft comprising:
- a mounting member securing the propeller to the aircraft; and
- at least one blade rotatably connected to the mounting member and having an airfoil shape, each blade having a locked condition during take-off and landing of aircraft extending parallel to an edge of the aircraft and an unlocked, rotating condition during flight for propelling the aircraft.
20. The aircraft recited in claim 19, wherein each blade is locked to direct air onto the edge to provide lift to the aircraft.
Type: Application
Filed: Feb 20, 2015
Publication Date: Aug 25, 2016
Applicant: NORTHROP GRUMMAN SYSTEMS CORPORATION (Falls Church, VA)
Inventor: ALLEN A. ARATA (Los Angeles, CA)
Application Number: 14/627,886