Rocket

About: Rocket is a research topic. Over the lifetime, 14018 publications have been published within this topic receiving 95852 citations. The topic is also known as: rockets.

Transpiration-Cooled Ceramic Thrust Chamber Applicability for High-Thrust Rocket Engines

Abstract: The development of ceramic rocket engine thrust chambers at the German Aerospace Center (DLR) currently concentrates on designs of self-sustaining, transpiration-cooled, fiber-reinforced ceramic rocket engine chamber structures. This paper discusses characteristic issues and potential benefits introduced by this technology. Achievable benefits are the reduction of weight and manufacturing cost, as well as an increased reliability and higher lifetime due to thermal cycle stability. This paper discusses the current status of DLR's ceramic thrust chamber technology and potential applications for high thrust engines. The test results of DLR's ceramic thrust chamber project KSK are used for a rough approximation of the performance of high thrust applications. Based on the KSK test results an extrapolation is performed. c*-efficiency and geometrical scaling effects are taken into consideration. Due to favorable scaling effects, high thrust applications will profit by all benefits of the discussed technology, while avoiding the most significant performance drawbacks.

Use of a Microphone Phased Array to Determine Noise Sources in a Rocket Plume

Abstract: A 70-element microphone phased array was used to identify noise sources in the plume of a solid rocket motor. An environment chamber was built and other precautions were taken to protect the sensitive condenser microphones from rain, thunderstorms and other environmental elements during prolonged stay in the outdoor test stand. A camera mounted at the center of the array was used to photograph the plume. In the first phase of the study the array was placed in an anechoic chamber for calibration, and validation of the indigenous Matlab(R) based beamform software. It was found that the "advanced" beamform methods, such as CLEAN-SC was partially successful in identifying speaker sources placed closer than the Rayleigh criteria. To participate in the field test all equipments were shipped to NASA Marshal Space Flight Center, where the elements of the array hardware were rebuilt around the test stand. The sensitive amplifiers and the data acquisition hardware were placed in a safe basement, and 100m long cables were used to connect the microphones, Kulites and the camera. The array chamber and the microphones were found to withstand the environmental elements as well as the shaking from the rocket plume generated noise. The beamform map was superimposed on a photo of the rocket plume to readily identify the source distribution. It was found that the plume made an exceptionally long, >30 diameter, noise source over a large frequency range. The shock pattern created spatial modulation of the noise source. Interestingly, the concrete pad of the horizontal test stand was found to be a good acoustic reflector: the beamform map showed two distinct source distributions- the plume and its reflection on the pad. The array was found to be most effective in the frequency range of 2kHz to 10kHz. As expected, the classical beamform method excessively smeared the noise sources at lower frequencies and produced excessive side-lobes at higher frequencies. The "advanced" beamform routine CLEAN-SC created a series of lumped sources which may be unphysical. We believe that the present effort is the first-ever attempt to directly measure noise source distribution in a rocket plume.

Optimal singular rocket and aircraft trajectories

Abstract: We give a brief review of optimal singular control rocket and aircraft trajectories in outer space and in the atmosphere. Singular control rocket and aircraft trajectories occur when the thrust is at intermediate levels. The analysis of a singular control rocket or aircraft trajectory requires the Goh-Legendre-Clebsch necessary conditions. Two sets of compact forms of these conditions are described. The first compact form of these optimality conditions is convenient for testing the optimality of a singular control trajectory. The second compact form is important because its strengthened form provides sufficient conditions for the control variables to be expressed in terms of the state and costate variables.