US3141295A - Propellant compositions - Google Patents

Description

N Drawing.

This invention relates to propellant compositions and more particularly to propellant compositions useful in the propulsion of rockets.

In the rocket propellant field, red or white fuming nitric acid is widely used as an oxidizer in conjunction with fuels to yield high energy propellants which can undergo spontaneous ignition upon mixing. To illustrate, a combination of red fuming nitric acid and hydrazine is considered, on the basis or" theoretical thermal calculations, to be a very powerful hypergolic rocket propellant composition. However, liquid fuming nitric acid presents many problems in handling and use because of its high reactivity, toxicity,and corrosive nature.

It is the principal object of this invention to provide safe to handle, efficient, non-hypergolic fuels and nitrogen oxide containing solid oxidizers which upon mixing as in the combustion of a rocket undergo spontaneous deflagration resulting in the release of high energy values normally associated with the interaction of fuming nitric acid and such fuels. Another object of the present invention is to provide propellants comprising a non-hypergolic fuel and a non-hypergolic solid oxidizer containing readily available quantities of oxygen. A further object is to provide a solid nitrogen oxide containing oxidizer which is essentially non-shock sensitive unlike some other solid nitrogen oxide containing compounds presently used as propellant oxidizers, e.g. nitronium perchlorate. Other objects and advantages will become apparent from the detailed specification presented hereinafter.

I have now discovered that certain solid, complex nitrogen oxide-boron trifluoride coordination compounds selected from the group consisting of nitronium tetrafiuoroborate (NO BF nitrogen trioxide boron trifiuoride complex (N O .BF nitrogen tetraoxide boron trifiuoride complex (N O BF and nitrogen pentoxide boron trifiuoride complex (N O .BF when admixed with conventional fuels yield propellants having excellent hypergolic properties. These propellants upon deflagration also produce large volumes of high temperature gases.

In such mixtures the complex nitrogen oxide boron trifiuoride compounds behave chemically much the same as does red fuming or White fuming nitric acid. However, the solid nitrogen oxide-boron trifluoride coordination compounds by themselves are easily and safely handled, stored and transported as these materials do not have the inherent toxicity and corrosive nature of the fuming nitric acids.

Fuels which have been found to provide hypergolic compositions upon mixing with the hereinbefore listed complex compounds fall into the following groups:

Group I.Symmetrical and asymmetrical lower alkyl substituted hydrazines and their salts wherein the lower alkyl groups contain from one to four carbon atoms.

Group II.Lower alkyl substituted polyamines wherein the alkyl groups contain from one to four carbon atoms.

Group 1II.-Aminodiborane (NH B H ammoniaaminodiborane complex (NI-I -NH B H or lower alkyl hydrazine aminodiborane complexes drazine contains from one to four carbon atoms.

Group IV.Cellulose, and ether and/ or ester derivaatent tives of cellulose wherein the molecular species reacted with the cellulose molecule to form the ether and/or ester are limited to those reactive compounds containing from one to two carbon atoms.

Group V.-Glycols, glycerols and polyols containing from two to six carbon atoms.

All of the aforementioned fuels when combined by simple mixing with the solid complex nitrogen oxide boron trifiuoride compounds of the present invention i.e. NO2BF4, N2O3.BF3, N204-BF3 and N2O5.BF3, undergo extremely vigorous thermal reactions evolving large vol umes of gases. While no action usually occurs immediately upon mixing the oxidizer and the fuel, after an induction period of from a few up to 30 seconds or more, a deflagration reaction proceeds instantaneously and almost explosively.

The amount of fuel that will react stoichiometrically with the oxidizer is dependent upon the replaceable hydroxyl, amino or alkyl substituted amino groups in a given fuel under the conditions of the reaction. Preferably the amount of fuel and solid oxidizer to be employed in a propellant composition will be such that the ratio of the nitric acid equivalents in the oxidizer to each of the above listed replaceable groups in a given fuel is from about 1:1 to about 8:1. Desirably a ratio from about 2:1 to about 4: 1 will be employed.

The following example is given to more clearly illustrate the invention but is not to be construed as limiting it thereto.

Example Nitronium tetrafluoroborate was prepared by the method reported by Olah, Kuhn and Mlinke (J. Chem. Soc. 1956, 4257-4259).

A propellant composition was prepared by admixing 10 mole parts of the nitronium tetrafiuoroborate with about 2.5 mole parts of dimethyl hydrazine hydrochloride. After a short induction period of approximately 15 seconds, the mix defiagrated with almost explosive velocity and liberated large volumes of gaseous products. In less than one minute the reaction mixture had consumed itself and only a small amount of inorganic residue remained.

In a manner similar to that described in the foregoing example, hypergolic compositions result from mixing N O .BF N O .BF or N O .BF (prepared as described by Bachmann and Hokama, J. Am. Chem. Soc. 79, 4370 [1957]) with a fuel member selected from the Groups I-V listed hereinbefore, utilizing from 1 to 8 equivalents (on the basis of equivalent nitric acid values in the oxidizer) for each equivalent of replaceable hydroxyl, amino or alkyl amino groups present in said fuel member. Such mixtures undergo spontaneous deflagration the same as was exhibited by the nitronium tetrafluoroborate-dimethyl hydrazine hydrochloride mix.

Various modifications may be made in the present invention without departing from the spirit and scope thereof for it is understood that I limit myself only as defined in the appended claims.

I claim:

1. A rocket propulsion method which comprises admixing in a rocket combustion chamber a fuel member selected from the group consisting of (l) symmetrical and asymmetrical alkyl substituted hydrazines and their salts, (2) alkyl substituted polyamines, (3) aminodiborane (NH B H and ammonia-amino diborane complex, hydrazine amino diborane (N H -NH B H complex and alkyl substituted hydrazine amino diborane (RNHNH -NH B H complexes wherein R is alkyl and wherein the alkyl substituents of each of the above listed fuel members contain from 1 to 4 carbon atoms, (4) cellulose, ether derivatives of cellulose and ester derivatives of cellulose wherein the molecular species reacted with the cellulose molecule to form the ether and the ester thereof are limited to those reactants containing from 1 to 2 carbon atoms and (5) polyols containing from 2 to 6 carbon atoms and an oxidizer selected from the group consisting of nitronium tetrafluoroborate nitrogen trioxide boron trifluoride complex (N O -BF nitrogen tetraoxide boron trifluoride complex (N O -BF and nitrogen pentoxide boron trifluoride complex wherein the quantities of said oxidizer and said fuel are such that the ratio of nitric acid equivalents in said oxidizer to each of the above listed amino, hydroxyl and alkyl substituted amino groups in said fuel member is from about 1:1 to about 8:1 thereby to produce a vigorous, hypergolic thermal reaction evolving large volumes of gases.

2. A rocket propulsion method which comprises; admixing in a rocket combustion chamber the oxidizer nitronium tetrafiuoroborate and the fuel dimethyl hydrazine hydrochloride wherein the ratio of nitric acid equivalents in said oxidizer to the alkylamine groups in said fuel is from 1:1 to about 8:1 thereby to produce a vigorous, hypergolic thermal reaction evolving large volumes of gases.

3. A rocket propulsion method which comprises; admixing in a rocket combustion chamber the oxidizer nitrogen trioxide boron trifluoride complex and the fuel dimethylhydrazine hydrochloride wherein the ratio of nitric acid equivalents in said oxidizer to the alkylamino groups of said fuel is from 1:1 to about 8:1 thereby to produce a vigorous, hypergolic thermal reaction evolving large volumes of gases.

4. A rocket propulsion method which comprises; admixing in a rocket combustion chamber the oxidizer nitrogen tetroxide boron trifluoride complex and the fuel dimethylhydrazine hydrochloride wherein the ratio of the nitric acid equivalents in said oxidizer to the alkylamino groups in said fuel is from 1:1 to about 8:1 thereby to produce a vigorous, hypergolic thermal reaction evolving large volumes of gases.

5. A rocket propulsion method which comprises; admixing in a rocket combustion chamber to oxidizer nitrogen pentoxide boron trifluoride complex and the fuel dimethylhydrazine hydrochloride wherein the ratio of the nitric acid equivalents in said oxidizer to the alkylamino groups in said fuel is from 1:1 to about 8:1 thereby to produce a vigorous, hypergolic thermal reaction evolving large volumes of gases.

References Cited in the file of this patent UNITED STATES PATENTS Stengel .v Sept. 6, 1960 Zletz et al. Feb. 7, 1961 OTHER REFERENCES

Claims (1)

1. A ROCKET PROPULSION METHOD WHICH COMPRISES ADMIXING IN A ROCKET COMBUSTION CHAMBER A FUEL MEMBER SELECTED FROM THE GROUP CONSISTING OF (1) SYMMETRICAL AND ASYMMETRICAL ALKYL SUBSTITUTED HYDRAZINES AND THEIR SALTS, (2) ALKYL SUBSTITUTED POLYAMINES, (3) AMINODIBORANE (NH2B2H5) AND AMMONIA-AMINO DIBORANE