1. Field of the Invention
The present invention relates to the field of controlled flow, exhaust manifold systems and, more particularly, to apparatus for controlling the flow of exhaust gases between a plurality of rocket stations and a common exhaust gas manifold or plenum tube connected thereto.
2. Description of the Prior Art
In many military applications, numbers of rockets are stored or disposed in closely adjacent magazine chambers, launch tubes, or the like, hereinafter referred to collectively as chambers. Exhaust gas outlets are normally provided, even from magazine storage chambers, to duct rocket exhaust gases generated during intended or accidental rocket ignitions to a safe location. Where available space is at a premium, for example on ships, manifolding of a number of chambers into a common exhaust duct or plenum tube is often necessary.
Obvious problems exist if ducts connecting the chambers to the common exhaust manifold are always or normally open. When one (or more) of the rockets is intentionally or accidentally ignited, at least portions of the resulting exhaust gases, which may be at about 6000.degree. F., will be circulated through the common manifold and into other chambers through the open connecting ducts. Rockets and rocket warheads in these other chambers are very likely to be ignited or be detonated by these hot exhaust gases. If these other rocket chambers are open at upper ends, as are launch tubes and some storage compartments, exhaust gases entering the chambers through the connecting ducts escape through the open ends and may cause extensive heat damage to adjacent installations.
To prevent such occurrences, some type of safety door or gas valve is normally installed either at the outlet opening of each rocket chamber or in the connecting duct to the exhaust manifold. When a rocket is accidentally or intentionally ignited, the associated safety door or gas valve is caused to open--usually by the exhaust blast--to admit the exhaust gases into the manifold. The doors or valves associated with other chambers are maintained in a closed condition to prevent circulation of the exhaust gases thereinto.
The patent disclosures, for example, of Eastman and Neuman et al. (U.S. Pat. Nos. 2,445,423 and 3,228,286, respectively) illustrate use of such doors or valves. Previously available or disclosed apparatus, however, have substantial disadvantages. For example, the patent of Neuman et al discloses at the bottom of each compartment of a multiple rocket storage magazine, a non-hinged, "blow out" door. These doors lead through conducting ducts to a common exhaust manifold. If any of the rockets in the magazine are accidentally ignited (for example by enemy fire), the force exerted by the resulting rocket exhaust gas on the upper surface of an associated door blasts the door out of its opening and admits the gases into the manifold. An associated fire extinguishing system is designed to direct pressurized water through the resulting opening and extinguish the rocket. A major disadvantage, however, is that no means are provided for automatically reclosing the door after the rocket has been extinguished. Unless the blow-out door is manually replaced--for which little provision seems to have been made--hot exhaust gases from subsequent accidental ignition of another rocket would enter the compartment and could cause reignition of the rocket or explosion of its warhead before such next-firing rocket is extinguished. In addition, if the compartments are not sealed in upper regions--which they do not seem to be--hot exhaust gases from the next firing rocket would be conducted through any compartments containing previously ignited rockets and directly to the rocket launching platform positioned just above the magazine.
Another very substantial problem associated with the apparatus disclosed by Neuman et al, and other similar apparatus, is that little consideration appears to have been given to preventing recirculation of exhaust gases back into and through a chamber while a rocket is firing in that chamber. Whatever type of exhaust flow control door or valve is used, it must be suitably configured to prevent exhaust gases emitted therethrough and into the exhaust manifold from flowing around the exhaust stream and back into the rocket compartment. If this occurs, the gases may cause structural damage to portions of the rocket, ignition of other propellants (if the rocket has other stages) or detonation of the rocket warhead. Ignition of these other propellants or detonation of the warhead could ignite or detonate adjacent rockets and warheads, thereby initiating a disastrous chain reaction.
Merely to provide properly opening and closing rocket exhaust gas flow control doors is, therefore, insufficient; the doors must be configured so that at all exhaust flow conditions they will open only that amount which will cause the rocket exhaust stream to function as a complete "gas plug" in the opening to prevent recirculation of exhaust gases back into the chamber.
The patent of Eastman discloses apparatus adapted for storing a number of rockets, wherein exhaust nozzles of the rockets are seated in sealing relationship upon short ducts or nozzle extensions leading to a common exhaust manifold. Toggle clamps are used to hold the noses of the rockets in the storage apparatus and no actual storage compartments are formed. Each nozzle extension has, at its lower end, a pair of hinged doors, spring biased to a normally closed condition. Exhaust gas pressure from an accidentally ignited rocket forces the associated nozzle extension doors to swing open against the springs, thereby admitting the gases to the manifold, from which they are discharged at a remote location. The resulting gas pressure in the manifold acts upon under sides of other closed doors to force them tightly closed and prevent circulation of hot exhaust gases into the other nozzle extensions.
However, the door hinges and biasing springs are positioned directly in the path of hot exhaust gas flow from an above firing rocket and will receive maximum heating and erosion therefrom. As a result of heat and erosion damage, the doors immediately below a firing rocket, even if not burned completely loose, as is likely, would probably fail to return to the closed condition after the firing. Also, very possibly, heat from hot exhaust gases flowing through the manifold would damage the biasing springs of other doors. Even if these doors were kept closed by pressure in the manifold during that particular firing, they might subsequently sag open. Then, upon a next accidental rocket firing, the flow of gases through the manifold could force the sagging doors open, rather than closed, allowing circulation of the hot gases into above nozzle extensions with consequent ignition of the associated rockets.
Even though spring-loaded flow control doors might be satisfactory for use associated with storage of small rockets, wherein firing is unlikely and when it occurs the firing time is short, such doors would be entirely unsatisfactory in applications in which they would be subjected to repeated or sustained rocket exhaust gas flows. They would thus be unsatisfactory for use associated with storing or launching large rockets or with launch tubes from which a large number of even small rockets would be fired.
For these and other reasons, improvements in controlling flow of rocket exhaust gases associated with a plurality of rocket stations and a common exhaust gas manifold are not only desirable, but necessary.