Swain, Robert L. | Search NASA

NASA NTRS1960

Flight Performance of a Spin-Stabilized 20-Inch-Diameter Solid-Propellant Spherical Rocket Motor

A successful flight test of a spin-stabilized 20-inch-diameter solid-propellant rocket motor having a propellant mass fraction of 0.92 has been made. The motor was fired at altitude after being boosted by a three-stage test vehicle. Analysis of the data indicates that a total impulse of 44,243 pound-second with a propellant specific impulse of approximately 185 was achieved over a total action time of about 12 seconds. These results are shown to be in excellent agreement with data from ground static firing tests of these motors. The spherical rocket motor with an 11-pound payload attained a velocity of 15,620 feet per second (m = 16.7) with an incremental velocity increase for the spherical motor stage of 12,120 feet per second.

Levine, Jack↗

NASA NTRS1959

Experimental and Analytical Study of Rolling-Velocity Amplification during the Thrusting Process for Two 10-Inch-Diameter Spherical Rocket Motors in Free Flight

Two 10-inch-diameter spherical rocket motors have been flight tested at the NASA Wallops Station. These tests were conducted to measure "spin-up" or amplification of the spinning velocity of the motor during the thrusting process due to internal swirling of the exhaust gases. Model 1, a heavy-wall motor, experienced an increase in spin rate during thrusting of about 10 percent, whereas model 2, a flight-type motor with a lightweight motor case, experienced an increase of about 19 percent. The propellant weight and geometry were the same for both motors. A simple relationship for "spin-up" which satisfies these measured results is reported herein. Both models were spin stabilized throughout their flights. A theoretical method of predicting spin-up was derived and used to extend the measured 10-inch-motor results to spherical rocket motors of other sizes having a similar propellant geometry. This method is presented and its predictions are shown to compare favorably with the measured flight results.

Martz, C. William↗