Ammunition and explosives – Having reaction motor
Reexamination Certificate
2001-03-07
2003-03-25
Carone, Michael J. (Department: 3641)
Ammunition and explosives
Having reaction motor
C102S520000, C102S380000, C102S381000, C060S251000, C244S003220, C244S130000
Reexamination Certificate
active
06536350
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of high-speed gun or artillery launched projectiles. Particularly the present invention relates to air-breathing propulsion assisted projectiles, and more particularly to air propulsion assisted projectiles that accelerate after launch. Even more particularly the present invention relates to fuel release systems used in air breathing propulsion systems that accelerate after launch.
2. Description of the Prior Art
The ramjet and supersonic ramjet propulsion cycles for supersonic and hypersonic engines are well known within the art of aerospace propulsion. In ramjet propulsion high velocity air is compressed through a series of forebody and inlet shocks and through a subsonic diffuser all of which decelerate the air to a subsonic velocity near the fuel flame speed. Fuel is injected into a combustor and conventional subsonic combustion increases the temperature and pressure of the fuel-air mix. The high-pressure gas is then expanded through a nozzle increasing the velocity and momentum of the flow to produce thrust. Ramjet can be efficiently used to a velocity of approximately Mach 5. Above Mach 5 the temperatures and pressure associated with decelerating the flow to subsonic speeds for combustion are severe and begin eroding the engine cycle and the engine structure. It is at this point when supersonic combustion ramjet, called scramjet, is the preferred form of propulsion.
For Mach numbers above 5, a principal advantage of scramjet propulsion is that supersonic velocities within the combustion chamber are accompanied by lower static temperatures, pressures, and reduced total pressure losses. By reducing combustion product dissociation, reduced temperatures increase combustion efficiency, reduced pressures decrease loads on engine structure, and reduced total pressure losses increase the flow energy available for thrust production.
Research in supersonic air breathing propulsion systems for aircraft and missiles has been in progress since the 1940's. As empirical knowledge grew on the subject in the 1950's, researchers investigated propulsion for hypersonic aircraft and missiles, using scramjet engines. Research into scramjet propulsion continued during the 1970's at the Nasa Langley Research Center and John Hopkins Applied Physics laboratory, and in the 1980's and 1990's work continued under the auspices of the National Aerospace Plane Program.
Starting in 1993 the Super High Altitude Research Project (SHARP) launched hypersonic air breathing vehicles for the purpose of data development on SCRAM propulsion. SCRAM propulsion has been discussed for several decades and is the cornerstone of many advanced vehicle concepts. The projectiles were launched using the SHARP hypervelocity launcher, which is a two-stage light gas gun. Because the flight duration was short, high specific impulse was required from the engine in order to produce a measurable deviation from pure ballistic flight. This lead to the selection of gaseous hydrogen as the fuel. One drawback of hydrogen is its low energy density. This, coupled with the low fuel volume available on the projectile, means that hydrogen must be stored at high pressure, e.g. 6000-10000 psi, and must not be prematurely released, i.e. before the projectile exits the launch tube. Using the SHARP light gas gun, velocities of up to MACH 9 have been recorded. The greatest advantage of the light gas gun launch is that high Mach number and high Reynolds numbers can be achieved simultaneously in invitiated air (clean). This guarantees that the flow field around a properly scaled model will match that of a full-scale hypersonic vehicle at operational speed and altitude. The primary disadvantage of the gun is that in gun launch there is a high axial acceleration load. In the SHARP test this can exceed 20,000 “g”. For this reason it is necessary that a robust mechanical design be implemented for launching the device.
Several devices have been created for use as projectiles for launch from a light gas gun. These devices take advantage of the characteristics inherent in scramjet and ramjet technology, and select hydrogen for its projectile fuel source. Hydrogen is selected as a gas source because, in order to achieve a measurable deviation from ballistic flight, an engine must produce high specific impulse, which is attainable using hydrogen.
U.S. Pat. No. 5,485,787 (1996, Bowcutt et al.) discloses a gas gun launched propulsion assisted scramjet projectile adapted to be fired from a gun preferably at velocities greater then MACH 5. The projectile includes a body with an internal combustion section, i.e. combustor, an external compression section, a nozzle section, and means for channeling fuel to the combustor to produce thrust greater than drag when the projectile travels at velocities greater then Mach 5. The projectile further includes a plurality of circumferentially spaced stabilization fins located at the nozzle end of the body. In addition the device includes a pusher for launching the device and protecting it from propulsive forces of the launch. One disadvantage of this device is that it is prone to fuel leakage and premature activation of the fuel system. A properly functioning fuel source is extremely important because of the low energy density of hydrogen gas. In addition, the projectile does not have provisions for repetitive cycling of the mechanism and testing before launch.
U.S. Pat. No. 5,513,571 (1996, Grantz et al.) discloses an air breathing propulsion assisted projectile designed to be rocket or gun launched and capable of accelerating to hypersonic velocities. This design includes a body having an encompassing cowl, an air compression section, an engine assembly located adjacent the air compression section, and a nozzle section located adjacent the engine assembly. The engine assembly includes apparatus for fuel storage and delivery to a combustion region. The rear end portion of the cowl is configured to direct the exiting combusted air and fuel mixture over the nozzle section of the body.
A scramjet system launched from a light gas gun for scramjet propulsion testing and experiments in a closed test chamber was documented in 1968 by H. H. King and O. P. Prachar in the Air Force Aero Propulsion Laboratory Technical Report AFAPL-TR-68-9. This study represents an early attempt to launch a scramjet-shaped projectile from a gun barrel, and the projectile was too small to contain a fuel source. The experiments were conducted only to assess the flight characteristics of scramjet models. Fuel sources were tested but only in conical shaped forms that did not constitute the principles of scramjet or ramjet technology.
All of these current projectile designs face the significant problem of utilizing their fuel source efficiently. The efficient use of hydrogen is significant because of its low energy density and the low fuel volume available on the projectile. Thus, it is critical that the fuel source is activated at the correct time and that all fuel is combusted. Inefficient fuel use leads to decreased projectile performance.
Therefore, what is needed is a scramjet projectile that incorporates a fuel release mechanism where the projectile design is able to withstand the high acceleration loads of a gun launch. What is further needed is a projectile powered by scramjet propulsion with a fuel activation source that is activated at a correct and consistent time after the projectile has left the gun muzzle. What is still further needed is a projectile that activates the fuel source without leaking or wasting uncombusted fuel.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an air breathing propulsion assisted projectile capable of travel at hypersonic velocities that will overcome some of the deficiencies and drawbacks of currently known air breathing propulsion assisted projectiles. It is another object of the present invention to provide a novel air breathing propulsion assisted projectile t
Cartland Harry E.
Hunter John W.
Carone Michael J.
Daubenspeck William C.
Gottlieb Paul A.
Semunegus Lulit
The United States of America as represented by the United States
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