DE977861C - Use of foam bodies with propellant components as binders and / or fuel in solid rocket propellants - Google Patents

Description

Use of foam bodies with propellant components as binders and / or fuel in solid rocket propellants. It is known to use foams containing explosives for explosive purposes. These explosive foams are used for explosive boats or torpedoes in particular because of their low density (less than rg / ml). Explosives of this type are described in US Pat. Nos. 2,768,072 and 2,845,025 , which, however, do not permit use as propellants because the criteria for explosives and propellants are fundamentally different. Apart from initial explosives, an explosive is usually detonated by a pressure wave (detonator capsule). There are explosives that cannot be ignited by a flame or, once ignited, cannot sustain combustion on their own. A fuel, on the other hand, is usually ignited by a flame. An explosive is therefore required to have the highest possible detonation speed or high explosiveness. A fuel, on the other hand, should deliver as high a special impulse as possible when it burns (high gas volume at the highest possible temperature and low molecular weight of the gases). The reaction time of an explosive device is therefore only a fraction of a second, while the conversion of a propellant charge can take several seconds to minutes. They are two completely different physical processes. For these reasons, a rocket propellant has a different composition than an explosive, even if individual chemical compounds are used both in explosives and in propellants (e.g. nitroglycerine, nitrocellulose).

However, it is always decisive that the composition is chosen in such a way that that if the specific impulse is as favorable as possible, the normal burn-up does not result in a Detonation may pass, if possible also not when pressure waves occur.

Solid rocket propellants will have a high density and a total Required to be free of cavities and for certain purposes (anti-tank and anti-aircraft missiles) a very high initial acceleration is required. This can only be done by a very short burn time of the rocket can be achieved.

Because the linear burn rate of the previously known rocket propellants is at max. 10 cm / sec, for rockets with ultra-short burn times (about i to 10 milliseconds) requires a propellant that has a very large burned surface owns. This large surface was previously due to a complicated structure of the Propellant reached. Rods, tubes, plates or foils are replaced by appropriate Brackets brought into the desired arrangement.

This type of propellant structure always involves a great deal of work connected and often provides unreliable performance data.

The invention relates to the use of in blasting technology known foamed plastics in a homogeneous mixture with known ones Propellant components as binding and / or fuel in solid rocket propellants known composition. The fuel has a large burn surface and consists of a foam plastic and one with the foamed plastic homogeneously mixed oxidizing agents, such as NC, NG, inorganic oxygen salts, such as NH4C104 or other chemical compounds with a favorable oxygen balance, like Hexogen, Nitropenta etc.

The plastic component can consist of a substance that acts as a fuel be prepared, the a) by chemical reaction during the polymerization a splitting off gaseous components and thereby creating a foam-like structure (diisocyanate, Polyglycol ethers or esters with free OH groups and H.0); or / and b) in the for Creation of a large surface before or during or after the polymerization a gas is introduced (polyester-styrene copolymer and air).

In case a) is in the presence of excess diisocyanate after Homogenization of the raw fuel mass with a high-speed mixer a calculated amount 1-I20 was added and the mixture was then poured into the propellant form or rocket case. The propellant mass foams and solidifies. Shedding can ever be carried out in a warm or cold state depending on the type of polyurethane components used.

In case b), the propellant mass is during the block polymerization a gas introduced. The propellant mass solidifies to a sponge-like one Body. The foam-like state of the plastic can also be achieved before it is introduced into the shape or combustion chamber can be generated. The polymerization then takes place in a Time during which the desired physical state is retained.

You can also use a finished thermoplastic in melted form Condition, expediently under pressure, gassed.

The ignition of the propellant produced in this way takes place in the cheapest way by a string-shaped pyrotechnic set of high deflagration speed or by a detonation fuse with a smaller diameter ("pyrochore" fuse the DuPont). These strand-like ignition charges are parallel to the longitudinal axis of the combustion chamber attached in this before pouring the propellant mass. Through this procedure becomes a simple production of ultra-short burners without manual labor achieved. Since the production method can be reproduced exactly at any time, one obtains reliable performance data. Example for a) A mixture of 10 parts of nitrocellulose, 25 parts of nitroglycerin, 10 parts of aluminum, 45 parts of ammonium perchlorate, 15 parts polyether containing hydroxyl groups, 4 to 10 parts of tolylene diisocyanate, 2 to 4 Share stabilizer, catalyst and auxiliaries etc. will be as desired Density of the foam mixed with 0.1 to 1.5 parts of water, poured and several Held at 70 ° C for hours.

When 0.3 parts of water are added to 100 parts of the mixture, a density of d = i, o is achieved after curing. The "burning rate" was 170 m / sec at 100 atm. Pressure. Example of b) 25 parts of an unsaturated polyester, dissolved in styrene, are mixed with 65 parts of ammonium perchlorate and 10 parts of aluminum and from 1 to 5 parts of catalyst, accelerator, foam stabilizer and other auxiliaries. The plastic foam is generated by blowing in air and placed in a mold to polymerize out. Depending on the content of accelerator and temperature, the foam solidifies after 10 to 5 minutes. In a further example of a propellant mixture, consisting of 70.011 / o ammonium perchlorate (50% <18 R, grain diameter), 16.8% hydroxyl-containing polyester, 8.4% tolylene diisocyanate, 2.0% copper chromite, 1.70 / 0 water, 1 .1% catalyst, wetting agent, anti-caking agent, a density of d = 0.9 was achieved.

»Burn rate« r = 225 mm / sec. at 3o atm, r = 555 mm / sec. at roo atm.

The propellants were also used as a forehead burner in steel sleeves Ignited with standard ignition mixtures under weak damming, 25 cm in length. Of the Burning off took place quickly, but without detonation. The burn times measured with a counter were about 0.2 seconds.

Claims (1)

PATENT CLAIM: Use of the foamed plastics known per se in blasting technology in a homogeneous mixture with propellant components known per se as binding and / or fuel in solid rocket propellants of known composition. Contemplated publications: USA: Patent No. 2768072, 2845 o25..