Flight Research of an Aerospike Nozzle Using High Power Solid Rockets

Abstract

Flight research has been conducted on an aerospike rocket nozzle using high power solid rockets. Two aerospike rockets and one conventional rocket were flown successfully to supersonic speeds, providing the first known set of transonic flight performance data for aerospike rockets. This paper describes the rockets, solid rocket motors, nozzles, and rocket instrumentation system. Flight test results are also discussed and compared with ground test results. Flight data show that all of the rockets successfully reached supersonic speeds with a maximum Mach number of 1.6 and a peak pressure altitude of nearly 30,000 ft. The aerospike nozzle efficiency was determined to be 0.96 from computational fluid dynamics (CFD) analysis. The rocket chamber pressures and thrusts of the aerospike rocket motors were lower than the conventional rocket motors. Because the same propellant formulation was used in all of the rocket motors, the discrepancy in pressure and thrust was most likely caused by a larger actual aerospike nozzle throat area than the designed throat area. Potential causes for the larger aerospike nozzle throat area are also discussed.nozzle coefficient of thrust CFD = computational fluid dynamics 2 d = diameter D = external aerodynamic drag of the rocket FADS = flush air data system F x = forces in the axial direction g = gravitational acceleration ISP = specific impulse M = Mach number m = rocket mass m & = rocket propellant mass flow rate P a = ambient pressure P c = rocket chamber pressure psig = pounds per square inch gage r = radius T = rocket motor thrust t = time u x = rocket velocity in the axial direction U ∞ = freestream velocity x = axial direction γ= specific heat ratio η t = nozzle efficiency factor ρ ∞ = freestream density θ = rocket elevation angle I. Introduction HE broad range of human and robotic space exploration missions to the Moon, Mars, and destinations beyond, as outlined in the President's Space Exploration Vision, will benefit from advances in technology from all systems of a space vehicle, including the propulsion system and its nozzle. Most space vehicles, including spacelaunch boosters, Moon and Mars landers, orbiters, space tugs, or deep-space interplanetary probes, rely on a nozzle to convert the energy generated in the propulsion system into the direct thrust necessary to propel them through space. This is true for chemical, nuclear thermal, solar-heating, and arc-heating rockets. Therefore, nozzle efficiency and its physical size have a primary effect on the overall performance of space vehicles. Increased nozzle efficiencies and shorter nozzle lengths translate directly into less weight, more payload, longer range, and lower costs across the entire spectrum of space vehicles.Reference 1 provides a broad review of advanced rocket nozzle technologies. In this reference, it is shown that altitude-compensating nozzle technologies, such as the expansion-deflection nozzle, aerospike or plug nozzle, dualbell nozzle, and dual-expander nozzle, can provide significant performance gains by a...

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