Test rocket motors

The constant-pressure bomb is a very suitable tool for the determination and the comparison of the combustion rates of different propellants. However, the combustion rate as a function of the pressure may also be determined using a small test rocket motor. The motor s diameter may be between 50 and 100 mm. The combustion pressure is varied inside the motor by varying a nozzle throat area. The influence of the geometry of the propellant grain occasionally may be significant, resulting in no good correlation between the combustion rate determined in a constant-pressure bomb and that in a test rocket motor. 

J. W. Cole, "Non-Destmctive Testing of Large Rocket Motors A State of the Art Survey," in Bulletin of the Joint Meeting—JANNAF Panel of Physical... 

Monographs on rockets and rocket propellants by the National Aeronautics and Space Administration (NASA), Lewis Research Center, Cleveland. These iaclude the foUowiag Solid Propellant Selection and Characteri tion, Report SP-8064,1971 Solid Rocket Motor Peformance, Report SP-8039,1971 Solid Rocket Motor Igniters, Report SP-8051,1971 Solid Rocket Motor Metal Cases, Report SP-8025, 1970, and Captive Eire Testing of Solid Rocket Motors, Report SP-8041,1971. 

The committee considered the small amounts of PCBs that are suspected to be present in rocket motors and concluded that these amounts are far too small to pose an environmental concern. No data on PCBs were provided in any of the tests that the committee evaluated. Any small amounts of PCBs that may be present from rockets treated would end up in one of the solid waste streams and be at a concentration well below regulatory limits. 

An ethylene oxide monopropellant rocket motor is considered part of a ram rocket power plant in which the turbulent exhaust of the rocket reacts with induced air in an afterburner. The exit area of the rocket motor is 8 cm2. After testing it is found that the afterburner length must be reduced by 42.3%. What size must the exit port of the new rocket be to accomplish this reduction with the same afterburner combustion efficiency The new rocket would operate at the same chamber pressure and area ratio. How many of the new rockets would be required to maintain the same level of thrust as the original power plant ... 

Combustion tests carried out for a rocket motor demonstrate a typical T combustion instability. Double-base propellants composed of NC-NG propellants with and without a catalyst (1 % nickel powder) were burned. Detailed chemical compositions of both propellants are given in Section 6.4.6 and the burning rate characteristics are shown in Fig. 6.29. The addition of nickel is seen to have no effect on burning rate and the pressure exponent is n = 0.70 for both propellants. 

The combustion tests conducted for a rocket motor show that the combustion becomes unstable below 1.7 MPa and that the burning acquires a chuffing mode in the case of the uncatalyzed propellant. However, as expected, the combustion is stable even below 0.5 MPa for the nickel-catalyzed NC-NG propellant, as shown in Fig. 13.13. Propellants for which the flame temperature decreases with decreasing pressure tend to exhibit T combustion instability. 

It is evident that the standing pressure wave in a rocket motor is suppressed by solid particles in the free volume of the combushon chamber. The effect of the pressure wave damping is dependent on the concentrahon of the solid parhcles, and the size of the parhcles is determined by the nature of the pressure wave, such as the frequency of the oscillation and the pressure level, as well as the properties of the combustion gases. Fig. 13.25 shows the results of combustion tests to determine the effechve mass fraction of A1 parhcles. When the propellant grain without A1 particles is burned, there is breakdown due to the combushon instability. When... 

Niioka, T., Mitani, T and Ishii, S Observation of the Combustion Surface by Extinction Tests of Spinning Solid Propellant Rocket Motors, Proceedings of the 11th International Symposium on Space Technology and Science, Tokyo, 1975, pp. 77-82. 

Fig. 14.19 shows a typical set of pressure versus time curves obtained from tests on a rocket motor. When the I/D ratio defined in Fig. 14.19 is increased, the head-end chamber pressure is increased drastically immediately after the ignition stage. These grains are seven-pointed-star-shaped neutral-burning grains (diameter D = 114 mm), and are made of an AP-Al-CMDB propellant with the composition nc(0-25), ng(0-31), Ita(0-08), ap(0-27), and ai(0 09). The ratio of the initial burning surface area (Ayg) to the nozzle throat area (Aj), = AygjAp and the ratio of the... 

The standard ASTM D2585 filament wound pressurized bottle test method utilizes a 0.15-m (5.75-in.)intemal diameter filament wound bottle as the test article. This standard test method (with variation in bottle sizes) has been used extensively by the rocket motor industry [47-50] to evaluate glass, aramid, and graphite fiber composite vessel performance. This test method has generally shown good results, but is a relatively expensive test method. Testing of one 0.5-m (20-in.) diameter bottle can cost up to 20K. Other disadvantages are ... 

Although the uniaxial test has traditionally received the most attention, such tests alone may be insufficient to characterize adequately the mechanical capability of solid propellants. This is especially true for ultimate property determinations where a change in load application from one axis to several at once may strongly affect the relative ranking of propellants according to their breaking strains. Since the conditions usually encountered in solid rocket motors lead to the development of multiaxial stress fields, tests which attempt to simulate these stress fields may be expected to represent more closely the true capability of the material. 

It should be noted that a new technique has been developed to cast large grains of solventless double-base proplnts for rocket motors. This means that in future it will not be always necessary to use composite proplnts in prepn of large rocket proplnt grains Refs l)Anon, "The Preparation and Testing of Explosives , Summary Technical Report of Division 8, NDRC Vol 1 (1946), 93ff la)W. Ley, "Rockets, Missiles and Space Travel , Chapman Hall, London (1951), 380 lb)Ar-mamentEngrg (1954), 40-4 (Composite proplnts for rockets) 2)W.A.Arendale, IEC 48, 725 -26 (1956) CA 50, 10411 (1956) (Fuel-binder requirement for composite proplnts) 2a)H.W. Mace, USP 2740702 (1956) CA 50, 9720 (1956) (Combustion accelerators for Amm perchlorate-asphalt proplnts) 3)P.J.Blatz,... 

A series of tests were conducted by the Ballistic Research Laboratory at the APRFR which ranged from developing techniques and methods of irradiating burning miniature rocket motors and strand burners from outside to inside the reactor core (in the glory hole) (Refs... 

Non-Destructive Test Method for Defects in Propellant Rocket Motors (Ref 11)... 

This ref pertains to a US patent for a nondestructive testing method and app for determining the presence of voids, cracks or discontinuities in solid substances by the use of radioactive gases as a tracer. Although developed specifically for use with large solid proplnt rocket motors, composed mainly of active ingredients such as ammonium perchlorate imbedded in an inert binder, the method is claimed to be applicable to other solids as well... 

This testing revealed that either instantaneous explns or igns occur with unsym-diethylene-triamine, UDMH in JP-4 propint, pure UDMH, and pure JP-4. The results of hypergolic ign studies are also reported. It was found in tests conducted using a small-scale rocket motor that immediate hypergolic ign occurred with fuels such as ethanol, JP-4, unsym-diethylenetri-amine and hydrogen] 2) J.C. Bailer et al,... 

R-Salz = cyclotrimethylenetrinitrosa-mine (german) 71 radicals, free radicals 324 Rakete = rocket 275 Raketenflugkorper = missile 218 Raketenmotor = rocket motor 275 Raketenpriifstand = rocket test stand 275... 

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