Crawford bomb

Die Crawford-Bombe dient zur Ermittlung der Brenngeschwindigkeit (- Abbrandgeschwindigkeit) von Festtreibstoffen. 

Eine eingehende Arbeitsvorschrift zur Bestimmung der Brenngeschwindigkeit in der Crawford-Bombe wurde vom -+ BICT aufgestellt (festgelegt in Technische Lieferbedingungen des BWB, TL 1376-701, Teil III, Blatt 7). 

The burn rates of propellants are determined in a strand burner (Crawford bomb/ acoustic emission technique) at various pressures using an inert gas for pressurization. This data, when fitted in the empirical relation r = a.P" provides the pressure index n and the coefficient a. This technique is highly useful as a first approximation and is extensively used for propellant screening and quality control. The bum rates at different pressures are also determined by static testing in a ballistic evaluation motors (BEMs) and burn rates are typically scaled up from 1-5% for full scale motors. 

Crawford Bomb.This devise was developed in USA during W WII for the rapid evaluation of burning rates of proplnts at various temps and pressures. 

Crawford bomb 66 cresylite = mixture of trinitrocresol and picric acid (french) crimping 66 critical diameter 66 CR-propellants = RDX containing rifle powders (USA) cross section ratio -> propellant area ratio 269 crusher 149 362 C.TD. = coefficient of detonation transmission (coefficient de self exitation) (french) 87 CTPB = carboxyl-terminated polybutadiene (USA) 61 329 cumulative priming 66 c.u.p. = coefficient d utilisation pratique (french) 198 cuprene 52 cupric salicylate 163 curing 67... 

If the gases flow continously out, as in the case of a rocket motor, the pressure remains almost constant throughout the combustion period. The linear burning rate and its variation with the temperature and pressure may be determined in a Crawford Bomb. The temperature coefficient of the burning rate is the variation per degree of temperature increase at constant pressure. The dependance on pressure is characterized by the pressure exponent (see above). 

The dependence of the combustion rate upon the pressure may be expressed by Eqs. (3.1) through (3.3). The parameters a, b, and n in these equations can be determined if the combustion rate at different pressures is measured. Such experiments are carried out in a specially designed vessel, the so-called constant pressure bomb or Crawford bomb. 

Strands of this material would not burn in the inert atmosphere of the Crawford type bomb, but they burned in air at 70°F at the rate of 0.023" per second. This compared with a burning rate for H9 propellant of 0.097 /sec at 1 atm and 0.36"/sec,at 1000 psi 70°F This cast cellulose acetate material has been employed for end restricting 8W and 20" diameter perforated cast OGK grains and thermally cycled JATO motors at -65, +70, +165°F. No cracks or separations of the cast acetate restrictions were observed but some softening and deformation was noted. after conditioning at +165°F. These rounds functioned satisfactorily when fired at either -65 or +165°F... 

Analysis of variance has also been applied in testing three factors of composite rocket propellant burning rate in Crawford s-bomb at lOObar and 20 °C temperature. The analyzed factors are contents of fine fraction in bimodal oxidizer mixture (C) contents ratio of oxidizer mixture-aluminum powder (B) and contents of burning rate catalyst (A). The obtained burning rate values are given in the table in mm/s ... 

In a pilot plant for producing composite rocket propellants a batch of propellant was produced with the idea of characterizing it by measuring the linear burning rate at different pressures in Crawford s bomb. The following values were obtained experimentally ... 

Boloron = mixture of concentrated nitric acid and dinitrochloroben-zene (Austria) 204 bomb drop test 39 bombe Bichel 33 bombe Crawford 66... 

In 1790 Adair Crawford and William Cruikshank first detected non-radioactive strontium in the mineral strontianite in Scotland. Metallic strontium was isolated in 1808 by Sir Humphry Davy. Radioactive Sr-90, like many other radionuclides, was discovered in the 1940s in nuclear experiments connected to the development of the atomic bomb. 

General Crawford proposed charging the new 65 lb LC bomb with mustard for use against beach targets. ... 

Crawford, Cook, and Whiting, Statistics, "Procurement, p. 21. (2) J. C. Driskell, W. K. Ginman, and M. A. Zizmor, Colored Smokes—Colored Smoke Trail Bombs E13, E13R1, and E13R2. TDMR 861, 3 Aug 44. (3) CWTC Item 1132, Standardization of Bomb, Smoke, Colored Streamer, M87, 31 Aug 44. 

Count Rumford (1813) was one of the first scientists to study the combustion heat of wood, of course not yet in an oxygen bomb calorimeter [138]. He determined that the combustion heat of 1 pound of very dry oak wood burning without smoke and smell and with an "inappreciable quantity of ashes and no charcoal" is able to increase the temperature of 31 457 pounds of water by 180 F. In our modem terminology the caloric value of this oak wood amounts to 13.17 kJ/g wet weight. Moreover, Count Rumford observed a striking similarity between his results and those of Lavoisier and Crawford. The original Table 1 of the author is presented in Figure 5. 

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