US2712496A - Jet fuel - Google Patents

Description

JET FUEL Sol Sltolnil; and Howard W. Kruse, Inyokern, Califi, as-

signors is the United States of America as represented by the fiecretary of the Navy No Drawing. Application November 19, 1948', Serial No. 61,141

1 Claim. (Cl. 52.5)

(Granted under Title 35, U. S. Code (1952), see. 266) This invention relates to fuels, and more particularly to fuels for jet motors.

A common fuel currently used in jet motors is aniline. Its use has two outstanding disadvantages. In the first place the freezing point of aniline is 6.2 degrees centigrade. Temperatures are often encountered at high altitudes or in arctic regions, where it is diflicult if not impossible to employ aniline as fuel, because it solidifies and does not flow. In the second place, the ignition delay of pure aniline is unduly long compared to the total burning time of the fuel. For example, when nitrogen tetroxide is used as an oxidizer, the ignition delay of pure aniline is in the order of 350 milliseconds. This is excessive in the light of the total burning time of around 8 seconds.

It is an object of this invention to provide improved jet motor fuels having low freezing points.

It is another object of this invention to provide jet motor fuels having short ignition delays.

It is a further object of this invention to provide improved fuels having higher specific impulses than prior fuels.

The freezing point of aniline has been lowered in the past by the addition of large quantities of N-alkyl anilines and/or furfuryl alcohol. Such mixtures contain large quantities of low energy additives, and in addition have long ignition delays. In the case of the furfuryl alcohol additives, the fuel becomes unstable during storage.

In accordance with the instant invention, the characteristics of aniline as a fuel are markedly improved by the addition of hydrazine. It has been found that hydrazine and aniline form a eutectic mixture when about 18% by weight hydrazine is dissolved in about 82% by weight aniline. This mixture freezes at approximately -39 centigrade.

More broadly expressed, a low freezing point fuel, and hence a fuel of definite advantage in jet motors, may be formed by dissolving hydrazine either in aniline or in one of the aliphatic derivatives of aniline, or in a mixture of aniline and/ or several of the aliphatic derivatives thereof. In such cases there is a eutectic proportion for which the freezing point is lower than for either pure hydrazine or pure aniline derivative.

Furthermore, the added hydrazine also serves to increase the specific impulse of the aniline, or aniline derivative, fuel; and also lowers the ignition delay of the fuel.

While all of the aliphatic derivatives of aniline, as well as aniline itself, or any combinations of these compounds, are benefited by the addition of hydrazine, it is preferred, after aniline itself, to employ in the mixture one or more of the N-substituted aliphatic derivatives of aniline, i. e., one or more of the group represented by:

RR'NCsHs 2,712,496 Fatented- July 5,. 1.955

Where R is one of the class consisting'of (1) An aliphatic radical (2) Hydrogen atom R is one of the class consisting of- (1), An aliphatic radical (2) Hydrogen atom CsH5 is a benzene radical Of the above compounds, aniline is the preferred basic fuel, the next preference being a fuel comprised of hydrazine dissolved in di methyl aniline. In either case, it; ispreferred to employ a eutectic mixture of: hydrazine in, the particular aniline compound used:

The striking advantage of using hydrazine to lower the freezing point may be seen in the following table, wherein aniline itself is used as the other compound in the mixture:

The effect upon ignition delay of dissolving hydrazine in aniline fuel is shown in the following table:

TABLE II Ignition Delay of Aniline-hydrazine, with Nitrogen Tetroxide as Oxidizer Percentage by Weight Ignition Delay, Milli- Hydrazine Aniline seconds Fuels composed of hydrazine dissolved in aniline and/ or aliphatic derivatives of aniline have been found to have the advantages of: lowered melting point, including formation of eutectic mixtures; lowered ignition delay; and higher specific impulse, than the same fuels without the hydrazine.

Specific examples of fuels which are improved in this manner by the addition of hydrazine and which are encompassed in the above general description are:

aniline methyl-aniline ethyl-aniline diethyl-aniline propyl-aniline isopropyl-aniline methyl-ethyl-aniline Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claim the invention may be practiced otherwise than as specifically described.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

A fuel comprising approximately 82% aniline by weight and 18% hydrazine by weight.

King June 21, 1949 Solomon Sept. 5, 1950 4 OTHER REFERENCES Zucrow, Liquid Fropellant Rocket Power Plants, Journal of the American Rocket Society, No. 72, pages 26-44, December 1947. (Copy in Div. 43.).

Klein, Fuels for Jets, 8., A. B. Journal, pages 22-28, December 1947. (Copy in Patent Ofiice Library.)

Liebhafsky, Chimie and Industrie, vol 56, No. 1, page 1.9, July 1946. (Copy in Bureau of Standards Library.)

Science News Letter, page 25, July 10, 1948. (Copy in Patent Office Library.)

Deming, General Chemistry, 3rd edition John Wiley & Sons, Inc., New York (1930), pages 155, 156. (Copy in Scientific Library.))