US3730793A - Ethyldecaborane or b5h9 with mixed cif5 oxidizer - Google Patents

Abstract

LIQUID ROCKET PROPELLANT SYSTEMS COMPRISING A FUEL, EITHER ETHYLDECABORANE OR PENTABORANE-9, AND AN OXIDIZER OF CIF5 MIXED WITH EITHER AN IODINE OXYFLUORIDE OR AN IODINE FLUORIDE-TETRANITRO METHANE MIXTURE.

Description

United States Patent 3,730,793 ETI-IYLDECABORANE 0R B H WITH MIXED ClF OXIDIZER Donald Pilipovich, Canoga Park, and John Q. Weber,

Topanga, Calif., assignors to North American Aviation, Inc. No Drawing. Filed Apr. 5, 1967, Ser. No. 629,865 Int. Cl. C0611 15/00 US. Cl. 149-22 4 Claims ABSTRACT OF THE DISCLOSURE Liquid rocket propellant systems comprising a fuel, either ethyldecaborane or pentaborane-9, and an oxidizer of ClF mixed with either an iodine oxyfluoride or an iodine fluoride-tetranitro methane mixture.

BACKGROUND OF THE INVENTION In missile design it is desirable to give the missile the capability of delivering a high payload. This is generally achieved by providing a propellant system that has a high specific impulse, 1,. Additionally, it is desirable that the propellant be relatively dense, so that the missile itself will not be unduly large. A convenient measure of this parameter is density impulse, I The I of a propellant system is arrived at by multiplying the I of the system and the propellant bulk density. An I of greater than 400 g.-sec./ cc. is desirable.

It is also desirable to provide propellant systems that are storable under conditions considerably less difficult to maintain than cryogenic. These criteria might be especially critical in, for instance, tactical missile applications.

High specific impulses and high densities have been achieved in storable propellants in the prior art by the use of fuels that are heavily loaded with solid light metals, such as boron, aluminum, and beryllium. While these loadings do meet the requirements of density, specific impulses, and storability, the fuel which results has unfavorable mechanical properties which make pumping and storing difiicult.

It is an object of this invention to provide new rocket propellant formulations.

SUMMARY OF THE INVENTION The rocket propellant system of the instant invention comprises a fuel selected from the group consisting of pentaborane-9 ('B H ethyl-decaborane (EDB) and mixtures thereof and an oxidizer comprising chlorine pentafluoride and either an iodine oxyfluoride or an iodine fluoride mixed with tetranitromethane.

B H and EDB are fuels known to the prior art. If they are oxidized by prior art storable oxidizers, such as inhibited red fuming nitric acid, N 0 H 0 or 'N I-I a satisfactory specific impulse is achieved. However, the density impulse is low. Generally, the density impulse for the named oxidizers with either B H or EDB is below 350 g.-sec./cc. A higher I is desirable in missiles of fixed dimensions, e.g. tactical missiles. In the instance of missiles of fixed dimensions, the I would be a more pertinent measure of the payload capacity than the 1,.

If the recently discovered high energy oxidizer, chlorine pentafiuoride, ClF is used in combination with EDB or B H high specific impulses, in the range of 298 to 307 sec., are achieved and density impulses of about 450 g.-sec./cc. are achieved. These are high, but they can be improved upon.

It has been discovered that a combination of ClF and other oxidizers with EDB and B H gives an optimum balance of specific impulse and specific density. The oxidizer mixed with ClF should be either an iodine oxyfluoride or an iodine fluoride mixed with tetranitromethane.

As in the prior art, the oxidizer system and the fuel should be present in about stoichiometric ratios. The proportion of the oxidizer other than ClF in the propellant is a function of the percentage of boron in the fuel used. If only ClF were used as an oxidizer, the boron containing fuel would combine with the ClF to produce BF However, if oxygen is present in the oxidizer, the boron containing fuel will burn to produce the combustion product BFO. It has been found that the combustion product BFO is more desirable than the combustion product BF since BFO has a lower enthalpy, indicating a higher specific impulse.

An excess of oxygen causes the combustion product H O to be formed in preference to the combustion product HF. This is undesirable as the combustion product H O indicates a lower specific impulse than the combustion product HF. Consequently, it is preferred that there be one mole of oxygen present in the oxidizer mixture for every mole of boron present in the fuel. As explained above, this maximizes the amount of the combustion product BFO and minimizes the amount of combustion product H O. The amounts of IP 0 and F10 are readily calculable from these criteria. In the case of tetranitromethane and TF the tetranitromethane supplies the one oxygen per boron atom while the dense oxidizer 1P is added to increase the specific density of the mixture to a point above the design I In general, an I of over 450 g.-sec./cc. is preferred. By proper adjustment of these oxidizer and fuel combinations, high specific impulses and specific densities can be achieved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples illustrate preferred embodiments of the novel compositions of this invention.

EXAMPLE I A liquid rocket propellant system is formulated, in weight percent of 22.8% IP 0, 68.2% ClF and 9% B H an I of 288 sec. and an I of 480 g.-sec./cc. are realized.

EXAMPLE II A liquid rocket propellant system is formulated, in weight percent, of 11.3% 'I NM, 17% IF 59.2% ClF 12.5% E'DB; an I of 285 sec. and an I of 482 g.-sec./cc. are realized.

[EXAMPLE HI A liquid rocket propellant system is formulated, in weight percent, of 18% F10 62% GE, 10% EDB; and I of 286 sec. and an I of 502 g.-sec./cc. are realized.

Since it is obvious that many changes and modifications can be made in the above-described details without departing from the nature and spirit of the invention, it is to be understood that the invention is not to be limited thereto exept as set forth in the appended claims.

3 We claim:

1. A rocket propellant system comprising a stoichiometric mixture of fuel selected from the group consisting of pentaborane-9, ethyldecaborane, and mixtures thereof;

and an oxidizer comprising chlorine pentafluoride and 5 References Cited UNITED STATES PATENTS 3,128,212 4/1964 Larchar, Sr. et al. 14922 X 3,354,646 11/1967 Maya et al. 149-l X OTHER REFERENCES Stacey et al., Advances in Fluorine Chemistry, vol. 4, Butterworths, Washington, DC, 1965, pp. 246 to 249.

LELAND A. SEBASTIAN, Primary Examiner US. Cl. X.R. 60214; 1491, 89