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.

Rocket exhaust plume radar attenuation and amplitude/phase noise.

Abstract: There has been a considerable interest recently in the attenuation of a microwave signal when it traverses an ionized exhaust plume of a rocket motor. A closely related and sometimes more serious guidance problem is the introduction of amplitude-modulated (AM) or phase-modulated (PM) noise onto the transmitted signal by the rocket exhaust plume. This paper reports the results of a set of measurements wherein X-band attenuation was measured simultaneously with AM/PM noise for seven different double-base propellant systems and a single rubber-base system. The method and limitations of the measurements are discussed. Results are reported for total attenuation and AM/PM noise, together with spectral distributions of the noise, generally between 3.9 and 40 kc. Peak attenuation and noise levels occurred in the aft regions of the plume. Noise and attenuation varied markedly with changes in propellant composition, the more severe levels of each resulting from the more highly aluminized systems. A correlation existed between the level of attenuation and the levels of AM/PM noise. Causes of the induced noise were explained using a model based on turbulent scattering of the radar beam.

Radio tomographic imaging of sporadic- E layers during SEEK-2

Abstract: . During the SEEK-2 Rocket Campaign in August 2002, a Dual Band Beacon (DBB) transmitting to Ground Receivers provided unique data on E-Region electron densities. Information from two rocket beacons and four ground receivers yielded multiple samples of E-region horizontal and vertical variations. The radio beacon measurements were made at four sites (Uchinoura, Tarumizu, Tanegashima, Takazaki) in Japan for two rockets (S310-31 and S310-32) launched by the Institute of Space and Aeronautical Science (ISAS). Analysis was completed for four sets of beacon data to provide electron density images of sporadic-E layers. Signals from the two-frequency beacons on the SEEK-2 rockets were processed to yield total electron content (TEC) data that was converted into electron density measurements. Wide variations in layer structures were detected. These included horizontal sporadic-E variations, vertical profiles of double, single, and weak layers. The radio beacon measurements were shown to be in agreement with the in-situ SEEK-2 sensors. The first tomographic image of a sporadic-E layer was produced from the data. The rocket beacon technique was shown to be an excellent tool to study sporadic-E layers because absolute TEC accuracy of 0.01 TEC Units can be easily obtained and, with proper receiver placement, electron density images can be produced using computerized ionospheric tomography with better than 1km horizontal and vertical resolution. Keywords. Ionospheric irregularities – Instruments and techniques – Mid-latitude ionosphere

Axisymmetrical annular plug propulsion system for integrated rocket/ramjet or rocket/scramjet

Abstract: The invention is an airframe which includes a vehicle ( 12 ) having a solid propellant rocket engine ( 14 ) and a ramjet or scramjet engine ( 16 ); a thrust plug ( 18 ) extending from an end ( 20 ) of the vehicle which directs combustion gases ( 23 and 64 ) produced by the solid propellant rocket engine or ramjet/scramjet engine to produce forward thrust; a longitudinal passage ( 38 ) extending from the end of the vehicle to an opening ( 30 ) forward of the end which receives external air directed by forward movement of the vehicle and in which solid propellant ( 32 ) of the solid propellant rocket engine is located, and wherein during rocket operation solid propellant is combusted to produce the combustion gases in the longitudinal passage which are conveyed by the longitudinal passage into contact with the thrust plug and during ramjet/scramjet operation the longitudinal passage is open to flow of external air after operation of the solid propellant rocket engine is completed and which supports mixing and combustion of the air/fuel by the ramjet/scramjet engine to produce combustion gases which are conveyed by the longitudinal passage into contact with the thrust plug.

A Model of Erosive Burning of Composite Propellants

Abstract: : Development of solid rocket motor designs which result in high velocity flows of product gases across burning propellant surfaces(notably, nozzleless rocket motors) is leading to increased occurrence of erosive burning. In this paper, a physically realistic picture of the effect of such crossflow on composite propellant combustion, based on the bending of columnar diffusion flames by the crossflow, is presented. This bending results in shifting of the diffusion flame heat release zone toward the surface, with consequent increased heat feedback flux from this flame to the surface and thus increased burning rate. A relatively simple analytical model based on this picture is developed for prediction of propellant burnings rate as a function of pressure and crossflow velocity, given only zero-crossflow burning rate versus pressure data. Model predictions and experimental results are compared, with reasonably good agreement being found. (Author)

Experimental results from the HERO Project: In situ measurements of ionospheric modifications using sounding rockets

Abstract: The HEating ROcket project HERO comprised the first in situ experiments to measure artificial ionospheric modifications at F layer heights set up by radio waves transmitted from the Heating facility at Ramfjord near Tromso in Northern Norway. Four instrumented payloads were launched on sounding rockets from Andoya Rocket Range during the autumn of 1982 into a sunlit ionosphere with the sun close to the horizon. The payloads recorded modifications, in particular, the presence of electron plasma waves near the reflection level of the heating wave. The amplitude and phase of the three components of the electric and magnetic fields of the heating wave were measured simultaneously as a function of altitude. Coherent spectra of the three electric field components of the locally generated electron plasma waves were obtained in a 50-kHz-wide band. At the same time quasi-continuous measurements were made on several fixed frequencies from 4 kHz to 16 kHz below the heating frequency and in the VLF-range using linear dipole antennas. Moreover, measurements were made of electron temperature, suprathermal electrons and local electron density along the rocket trajectory. The experimental results will be presented and discussed.