Aeronautics and astronautics – Aircraft sustentation – Sustaining airfoils
Reexamination Certificate
1999-11-04
2001-01-30
Eldred, J. Woodrow (Department: 3644)
Aeronautics and astronautics
Aircraft sustentation
Sustaining airfoils
C244S15300R, C244S154000, C244S900000, C244S901000, C244S03500A, C244S11700R
Reexamination Certificate
active
06179248
ABSTRACT:
SUMMARY OF THE INVENTION
This invention relates to aircraft, and particularly to a novel aircraft, suitable for unmanned operation, and deployable from a collapsed condition by inflation.
A delta-shaped, low aspect ratio, lifting body configuration has been found to be ideal for a large scale aircraft taking advantage of both aerodynamic and static lift, as described in U.S. Reissue Pat. Re. 28,454, dated Jun. 17, 1975. The delta-shaped lifting body configuration also exhibits desirable characteristics for use in heavier-than-air aircraft of various sizes. As stated in U.S. Pat. No. 3,684,217, dated Aug. 15, 1992, delta wing lifting bodies possess favorable stall characteristics and are capable of relatively high cruising speeds and low landing speeds. Moreover, they can be made to carry large payloads efficiently. For example, as described in U.S. Pat. No. 4,896,160, dated Jan. 23, 1990 and 5,034,751, dated Jul. 23, 1991, a delta-shaped lifting body aircraft is ideally suited as an airborne surveillance platform, carrying a large radar antenna array.
A delta-shaped lifting body is characterized by a generally triangular, or delta-shaped, planform with a narrow nose at one corner, leading edges extending from the nose to the respective opposite corners, and a trailing edge extending from one of said opposite corners to the other. The planform is substantially symmetrical about an imaginary plane of symmetry extending from the nose to the midpoint of the trailing edge. The cross-sections of the hull transverse to the plane of symmetry are generally ellipse-like at the leading edges, convex at the upper surface, and, depending on the airload, concave at the lower surface. These cross-sections progressively decrease in height, while continuing to increase in width, from an intermediate location near, but aft of, the nose of the aircraft toward the trailing edge. The cross-sections of the hull extending from the nose to the intermediate location at which the height of the cross-sections begins to decrease, may progressively increase both in height and width.
The delta-shaped lifting body has the advantages that its entire surface serves as an airfoil, and its internal volume provides a large payload-carrying space.
Heretofore, maintaining a lifting body shape required a complex array of tensioning cables connected to various points on the interior of the hull, or alternatively a rigid framework on the inside of the hull. Without tensioning cables or an internal framework, flexible material, when inflated, will assume the shape of a sphere, or at best a surface of revolution, e.g. a blimp, neither of which has desirable airfoil characteristics.
The principal object of this invention is to achieve a delta-shaped lifting body without the need for a rigid framework or a complex array of tensioning cables. Another object of the invention is to provide a delta-shaped lifting body which can be deployed from a collapsed condition by inflating it with a stored, compressed gas.
The aircraft in accordance with the invention comprises plural inflated, flexible tubes, preferably elongated and in the form of surfaces of revolution with coplanar axes substantially intersecting one another at a location adjacent the nose of the aircraft, and diverging from one another from the nose toward the trailing edge. Each tube has an upper surface and lower surface, a nose end, preferably with a large cross-section, adjacent to the nose of the aircraft and a tip end, preferably with a smaller cross-section, adjacent to the trailing edge of the aircraft. Each tube preferably tapers to its tip end at least from an intermediate location between its nose end and its tip end. A length of cable extends along the trailing edge and connects the tip end of each tube with the tip end of each adjacent tube. A first membrane spans the upper surfaces of the tubes and constitutes an upper airfoil surface of the aircraft. A second membrane spans the lower surfaces of the tubes and constitutes a lower airfoil surface of the aircraft.
The aircraft may also include a second length of cable extending substantially parallel to the first length of cable and positioned aft thereof, and a flap comprising a strip of flexible material extending from the first length of cable to the second length of cable.
In a preferred embodiment, each of the plural, inflated, elongated flexible tubes has a rigid plate located at its tip end, a clamping member fixed to the plate and extending into the interior of the tip end, and a clamping ring securing the tip end to the clamping member. The cable may be connected directly to each rigid plate. Preferably, at least one of the first and second membranes is connected to the length of cable. The cable preferably has a provision for tension adjustment, which may be threads at both ends, allowing the cable to be adjustably connected to the rigid plates by nuts engaged with the threads.
Each of the plural, inflated, elongated, flexible tubes also preferably has a rigid plate located at its nose end, a clamping member fixed to the plate and extending into the interior of the nose end, and a clamping ring securing the nose end to the clamping member.
The rigid plates at the nose ends of the tubes may be rigidly connected together, and a propulsion motor may be connected to the plates by a gimbal assembly.
The aircraft is capable of remote-controlled or programmed low-speed flight, and is particularly suitable as an unmanned platform for reconnaissance, surveillance, or electronic countermeasures (ECM), such as carrying a camera, radio or radar, equipment or other suitable surveillance or ECM devices. An important advantage of the invention is that it can be transported in a collapsed condition and deployed for flight by inflation. Thus the aircraft is especially suited for exploration in extraterrestrial planetary atmospheres by deployment from a spacecraft, and for deployment from an aircraft, guided missile, gun-launched projectile, etc.
Other objects, details, advantages and modifications of the invention will be apparent from the following detailed description when read in conjunction with the drawings.
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Putman William F.
Smith Brian
Aereon Corporation
Eldred J. Woodrow
Howson and Howson
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