Aeronautics and astronautics – Aircraft structure – Fuselage and body construction
Reexamination Certificate
2000-02-25
2001-09-11
Jordan, Charles T. (Department: 3644)
Aeronautics and astronautics
Aircraft structure
Fuselage and body construction
C244S120000, C244S119000, C244S132000
Reexamination Certificate
active
06286785
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
REFERENCE TO A MICROFICHE APPENDIX
Not applicable
BACKGROUND OF THE INVENTION
The invention pertains to the field of aircraft mechanical structures, specifically, a safety system designed to provide additional reinforcement for the fuselage frame and aluminum skin by incorporating high performance Kevlar solid fabric for fuselage section jackets, and aircraft aluminum external paneling to provide support for the jackets.
I have no knowledge of prior or existing technology which duplicates the design, construction, operation and scope of my invention.
Aluminum alloy (Alcoa, Inc.) is used for fuselage/wing frames and skins. The thin aluminum skin and fuselage frame, are the only protective barriers (excluding cabin paneling) between the crew, passengers and potential disaster. Aircraft aluminum alloy is efficacious because of its light weight and heat resistance. However, there are several major deficiencies:
1. Aircraft aluminum has a lower tensile strength: ultimate strength by a material at the moment of failure (81,000 psi) than Kevlar (485,000 psi). Aluminum also has a lower modulus of elasticity: material's resistance to extension (10,600,000 psi) than Kevlar (14,000,000 psi).
2. Because of aluminum's low tensile strength and modulus, the fuselage frame and skin have less impact, cut, tear and puncture resistance than Kevlar. When an aircraft crashes at high speed, fracture and disintegration of the aluminum fuselage frame and skin can occur immediately upon impact. These events increase the probability and extent of fire, smoke, toxic gases and explosion, usually resulting in a high incidence of fatalities.
3. The aluminum skin is subject to salt water corrosion (salt water eats away parts) as the plane ages. This could lead to fuselage skin wear and stress fractures (“skin panel lap joints”). The cracks could cause a rapid decompression and lead to a crash or loss of the plane. In one major event, a fuselage crack turned into a hole in the plane, caused a decompression explosion, and ripped off the top of the fuselage (eighteen feet of roof). A flight attendant was sucked out of the plane. The official finding: the fuselage disintegrated after “disbonding of overlapping skin, metal fatigue and separation in the aircraft's skin and structure.”
BRIEF SUMMARY OF THE INVENTION
The invention presents a system designed to maintain aircraft structural integrity by providing increased reinforcement to the fuselage frame and aluminum skin, by the addition of fuselage section Kevlar fabric jackets and aircraft fuselage frame aluminum external paneling. The system does not replace any component of the existing mechanical structural system. The main purpose is to prevent the loss of the aircraft during high-speed impact crashes and accidents by reducing the extent of fuselage breakup, thereby increasing crew and passenger survivability.
OBJECTS AND ADVANTAGES
Kevlar fabric did not present instances where significant areas would experience immediate failure or disintegration by impact, tearing, fire or other adverse conditions. Therefore, the use of Kevlar in an primary structure (fuselage), in conjunction with added fuselage frame aluminum external paneling, should strengthen the existing aircraft structural system, which is basically comprised of a thin aluminum skin covering the fuselage frame. Kevlar is superior to aircraft aluminum alloys used for the fuselage frame and skin, in the following areas:
1. Kevlar has higher tensile strength (485,000 psi) and modulus of elasticity (14,000,000 psi) than aluminum. Aluminum has a tensile strength of 81,000 psi and a modulus of 10,600,000 psi. Kevlar's superiority should increase the airframe's capacity to resist high-tension loads in the fuselage during high-speed impact events, and reduce the extent of breakup and disintegration of the aircraft. The majority of accidents occur during takeoff or landing, and involve aborting a takeoff, failed landing gear, overshooting a runway, or running off the side of the runway. In most instances, they are non-fatal. However, if fire erupts, the chance of fatalities greatly increases. Most people who die in plane accidents, die from smoke inhalation or toxic fumes. Therefore, the use of Kevlar with its higher tensile strength and modulus of elasticity, and good thermal resistance, should reduce the probability and extent of fire, smoke, toxic gases and explosion, and increase crew and passenger survivability.
2. Kevlar's superiority to aluminum in tensile strength and modulus, should increase the airframe's capacity to resist penetration and tearing during accidents and crashes. There are numerous cases when aircraft debris and engine parts, such as fan blades/disks, etc., break loose and penetrate the fuselage, strike passengers and cause injuries or deaths. A breach in the fuselage may lead to a decompression explosion and blow away some or all of the fuselage.
3. Kevlar has excellent corrosion resistance. Unlike aluminum, it does not corrode in salt water. Kevlar's applications are well established in the marine environment. It is used for lightweight rope (tough mooring lines used on supertankers), primary umbilical cables for unmanned undersea work vehicles, diving bell support systems and submarine tow cables. Therefore, its use should reduce the incidence and extent of salt water corrosion as a plane ages. This could prevent aircraft fuselage skin stress fractures in the “skin panel lap joints,” and subsequent “separation in the aircraft's skin and structure,” which can cause rapid decompression and possible crash or loss of the plane. Additionally, Kevlar's thermal corrosion resistance justifies its use for high temperature reinforcement for rocket motor insulation.
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Best Christian M.
Jordan Charles T.
LandOfFree
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