Showing papers on "Rocket published in 1975"

Stability of Three-Dimensional Motions in a Combustion Chamber

Abstract: The problem oflinearized three-dimensional motions in a non-uniform flowfield is re-examined. Several modifications of the general analysis are effected: The influence of particulate matter is acounted for, to zeroth order, and certain boundary processes treated in earher one-dimensional computations are incorporated in an analysis applicable to any geometry. All processes occurring in combustion chambers are accommodated. As a specific example, the results are applied to a problem of linear stability in solid propellant rocket motors.

Thrust chamber life prediction. Volume 1: Mechanical and physical properties of high performance rocket nozzle materials

Abstract: Pertinent mechanical and physical properties of six high conductivity metals were determined. The metals included Amzirc, NARloy Z, oxygen free pure copper, electroformed copper, fine silver, and electroformed nickel. Selection of these materials was based on their possible use in high performance reusable rocket nozzles. The typical room temperature properties determined for each material included tensile ultimate strength, tensile yield strength, elongation, reduction of area, modulus of elasticity, Poisson's ratio, density, specific heat, thermal conductivity, and coefficient of thermal expansion. Typical static tensile stress-strain curves, cyclic stress-strain curves, and low-cycle fatigue life curves are shown. Properties versus temperature are presented in graphical form for temperatures from 27.6K (-410 F) to 810.9K (1000 F).

Echo 2 - A study of electron beams injected into the high-latitude ionosphere from a large sounding rocket

Abstract: The Black Brant V-C Echo 2 rocket was launched at Fort Churchill on September 25, 1972, and it injected 64-ms pulses of electron beams of 80-mA current and 45-keV voltage into the ionosphere. This paper studies the responses of on-board electrostatic deflection and solid state detectors to injected electrons after motion in the near ionosphere and atmosphere. It is shown that it was only through some form of scattering that the detectors could sense the injected beam electrons. By means of ‘phase maps’ of injection and detection pitch angles a number of distinct regions are found corresponding to a rocket scattering halo, an atmospheric scattering halo, a region of weak responses, and a source of strong scattering above the rocket. The atmospheric scattering has been compared with the theoretical and experimental results of the Echo 1 experiment, and it is found to be in reasonable agreement. The rocket halo is discussed qualitatively; but no explanation is found for the backscatter from above the rocket, which may be associated with an occasional violent beam instability. This analysis has been carried out to better understand the complexities of electron motion observed near large rockets carrying artificial electron accelerators as a guide in the planning of future experiments.

Theoretical study of gyroresonances with application to rocket experiments

Abstract: The waveforms and envelopes of resonance signals observed in the ionosphere at 2, 3, 4, and 5fH by rocket experiment are compared with the analytical results provided by a spatial ray-tracing procedure which takes the gradient of Earth's magnetic field into account. An approximate calculation yields the algebraic expression of the wave damping from whence the decrease of the received signals is deduced versus time as well as their frequency variations.

Rocket engine mount

Abstract: An engine mount to position a rocket engine within a missile stage and to lease the engine upon burn-out. A separation ring comprising a bracket portion and a shroud portion encircles the engine. The bracket is located approximately mid-length of the engine and wound thereon to engage the engine-circling sheath having a grooved and unsymmetrically weakened cross-section. The shroud is joined to the interior of an on-flying missile stage. A small rocket and fail-safe abutment ensure that the motor will be released in a direction opposite to the continuing flight path of the parent stage.

Simultaneous measurements of auroral particles and electric currents by a rocket-borne instrument system: Introductory remarks

Abstract: A rocket-borne experiment package has been designed to obtain simultaneous in situ measurements of the pitch angle distributions and energy spectra of primary auroral particles, the flux of neutral hydrogen at auroral energies, the electric currents flowing in the vicinity of the auroral arc as determined from vector magnetic data, and the modulation of precipitating electrons in the frequency range 0.5-10 MHz. The experiment package was launched by a Nike-Tomahawk rocket from Poker Flat, Alaska, at 0722 UT on Feb. 25, 1972, over a bright auroral band. This paper is intended to serve as an introduction to the detailed discussion of results given in the companion papers. As such it includes a brief review of the general problem, a discussion of the rocket instrumentation, a delineation of the auroral and geomagnetic conditions at the time of launch, and comments on the overall payload performance.

Technology and methodology of separating two similar size aerospace vehicles within the atmosphere

Abstract: During the past 10 years, the parallel separation, within the atmosphere, of two similar size aerospace vehicles has been investigated in technical areas such as static and dynamic stability, rocket exhaust plume interference, aerodynamic control, loads, and dynamic simulation. Advanced experimental and analysis techniques have been developed to analyze this problem. Results are presented which summarize some of this work. The effects of various parameters on the separation maneuver are illustrated using results from early and current space shuttle configurations. The technology and methodology that have been developed have helped verify the feasibility of separating similar size aerospace vehicles.

Apparatus for drilling holes in earth surface

Abstract: The apparatus is a rocket with a drill head provided with a group of jet nozzles. One nozzle of this group is the face-forming one, while the plurality of the rows of the rest of the nozzles belong to imaginary circles concentric with the longitudinal axis of the rocket. The spacing of the nozzles in each row equals 4 to 7 critical diameters of the jet nozzle of the respective row, while the spacing of any pair of the adjacent rows of the nozzles in a projection of the drill head upon a plane perpendicular to the longitudinal axis of the rocket is 4 to 7 times greater than the mean diameter of the nozzles of the said pair of rows of nozzles.

Simultaneous investigation of parent electrons and Bremsstrahlung X rays by rocket‐borne detectors

Abstract: Simultaneous measurements of the energy spectrum of precipitating electrons and the resulting bremsstrahlung X-ray spectrum were carried out during an auroral event on March 3, 1971, at the Churchill Research Range, Manitoba, Canada. The electron data were obtained with detectors on a Black Brant VB sounding rocket (275-km apogee), while the X-ray flux was measured by an instrument package that was boosted to 60 km on an Arcas rocket. The X-ray package was deployed on a parachute at apogee to provide a slow descent through the atmosphere. Thick-target bremsstrahlung theory is used to calculate the X-ray flux produced by the incident electrons, and a Monte Carlo method is used to predict the X-ray spectrum at various altitudes appropriate for comparison with the measured X-ray data. Satisfactory agreement between theory and experiment is obtained, and the value of the constant in the thick target theory has been estimated to be about 0.00002.

Optimum exhaust velocity for laser-driven rockets

Abstract: The laser-driven rocket in which remotely generated laser power is used to heat propellant belongs basically to the class of specific-impulse limited propulsion systems if difficult missions are considered. It was previously established that trip time reaches a minimum as specific impulse is varied for payload transfers from low earth orbit to synchronous orbit and return via laser-driven rocket propulsion, the computations being based on the perigee-propulsion laser drive described by Minovitch (1972). The present study shows that such minimum occur for all missions and that optimum specific impulse is primarily determined by the mission difficulty. More generally, this optimum specific impulse maximizes payload kinetic energy achievable with a fixed jet power and propulsion time. A formula relating propulsion time parameter to payload ratio is obtained for estimating mission capabilities of laser-driven rockets.

Measurements of a Simulated Rocket Exhaust Plume near the Prandtl-Meyer Limiting Angle,

Abstract: : Direct measurements of the mass flux level and estimates of the mass velocity have been made in the side flow field of a small axisymmetric rocket nozzle operated in hard vacuum. A shock tube provided nitrogen and simulated rocket propellant (nitrogen tetroxide and Aerozene 50) sources for the nozzle. Data were recorded in the plume far field, for angles ranging from 0 to 90 degrees relative to the nozzle centerline. In all cases, substantial mass flux levels were observed in the neighborhood of the limiting Prandtl-Meyer characteristic. At an angle of 90 degrees to the nozzle centerline, the density levels were typically three orders of magnitude below centerline values and the mass velocities were approximately one-half of the centerline values. (Modified author abstract)

Preliminary Assessment of the Potential Impact of Solid-Fueled Rocket Engines in the Stratosphere

Abstract: Free chlorine atoms produced from HCl deposited by solid-fueled rocket engines react to destroy odd oxygen in the stratosphere. Using a one-dimensional photochemical model, we have computed the reduction of ozone likely to be caused by long-term operation of such vehicles powered by large solid-fueled rocket engines. It is likely that ozone reduction will not be greater than a few tenths of a per cent, although the value is dependent upon ambient NO(x) concentrations.

Folding tail fins

Abstract: A rocket having flip out tail fins with cooperating surfaces on said fins d the rear of said rocket to maintain said fins in extended position. Spring means for urging said cooperating surfaces into engagement with each other.

Vertical sensing and control system

Abstract: A rocket powered escape vehicle is equipped with an electrostatic attitudeensing system which commands a rocket motor mounted in gimbals on the bottom of the vehicle to provide a vertically upward seeking escape from an aircraft independent of aircraft attitude.

Causes of ionization in rocket exhausts

Abstract: Forty-nine radar attenuation tests at ^f-band frequency were made using 1 Ib solid propellant charges in an altitude facility at ambient pressures of 280 and 140 mm Hg. Transverse attenuation was measured along the exhaust plume, using a moving microwave cart. Propellant aluminum level, solids loading level, and potassium impurity level were systematically varied. Tests were conducted in nitrogen and air atmospheres. Results of these tests were compared with predicted attenuation levels which were based on equilibrium thermal ionization of the alkali metal during afterburning of plume and ambient air. Microwave attenuation predictions considered a lineof-sight ray traversing a series of uniform sections of the ionized plume. Agreement of predicted and measured peak attenuation levels was excellent for a wide range of propellant formulations, providing evidence as to the causes of ionization.

A measurement of perpendicular current density in an aurora

Abstract: A Nike Tomahawk sounding rocket was launched into a 400-gamma auroral substorm from Esrange, Kiruna, Sweden. The rocket instrumentation included a split Langmuir-probe plasma-velocity detector and a double-probe electric-field detector. Above 140-km altitude, the electric field deduced from the ion-flow velocity measurement and the electric field measured by the double probe agree to an accuracy within the uncertainties of the two measurements. The difference between the two measurements at altitudes below 140 km provides an in situ measurement of current density and conductivity. Alternatively, if values for the conductivity are assumed, the neutral-wind velocity can be deduced. The height-integrated current was 0.11 A/m flowing at an azimuth angle of 276 deg. The neutral winds were strong, exhibited substantial altitude variation in the east-west component, and were predominantly southward.

Rocket experiment on spontaneously and artificially stimulated VLF plasma waves in the ionosphere

Abstract: In situ active experiments on the nonlinear wave-wave and wave-particle interactions in the ionospheric plasma were performed by a Japanese sounding rocket K-9M-41. Both spontaneously and artificially stimulated plasma waves in the VLF range were observed. When a large amplitude electron plasma wave was transmitted from the rocket, parametrically excited ion acoustic waves were observed in addition to natural emissions such as whistlers, LHR emissions, and hisslike emissions. It was also found that ‘risers’ were triggered by the LHR emissions, which seem to be very similar to a phenomenon of the so-called ASE (artificially stimulated emissions). When a slow electron beam with energy lower than 3 eV was ejected from the rocket, a new type of periodic U-shaped discrete emission was observed which was excited through a wave-particle interaction. The frequency of these emissions is lower than the LHR frequency and decreases as the beam energy is increased. Spectrograms of the observed plasma waves are presented, and some are analyzed theoretically.

Investigation of factors which contribute to mallaunch of free rockets

Abstract: : The simulation of the motion of a single-round launcher/rocket system during launch, transition to free flight, and free flight of the rocket is considered. A simple physical model for the system is described. The model consists of an arbitrary rigid-body launcher, with 3 deg of rotational freedom, and an arbitrary rigid-body rocket, which is attached to the launcher during the spin-up (if applicable), detent, and guidance phases by 'springs.' These springs are intended to model the flexibility and damping characteristics of the rocket's shoes or the interface between the rocket and the tube of a tube-type launcher. The model also includes the effects of thrust malalignment, tipoff, variable thrust, and spin torque programs and friction. Using modern vector/ matrix algebra, the vector equations are converted to matrix equations, amenable to digital programming and solution. Results of preliminary simulation runs made using a computer code written to perform the required numerical integration are presented and discussed.

Rocket-borne measurements of auroral electrons

Abstract: Rocket measurements of the pitch-angle and energy distributions of precipitated electrons in the 1- to 20-keV range show a consistent and relatively simple pattern. Features such as 'monoenergetic peaks' and pitch-angle distributions showing intense field-aligned components, rather than being anomalous, are characteristic of bright well-defined auroral forms. Presently available observations do not allow the identification of specific acceleration mechanisms, although they are consistent with several possibilities.

Rocket-powered apparatus for launching a flying device

Abstract: A rocket-powered vehicle is held latched at the starting end of its guide track while a high steam pressure is built up within the rocket casings through probes inserted into the nozzles which also seal them. When the latch is released, the rockets move off the probes to unblock the nozzles whereby the rockets propel the vehicle down the track to launch the flying device.

Support system for rocket thrust nozzles

Abstract: A system for mounting a movable thrust nozzle to a rocket case, wherein a plurality of cups surrounding the nozzle is fixed in a common plane to one of the members (the nozzle or case) and a plurality of plugs, each loosely fitting into a corresponding one of the cups, is fixed to the other member. The plugs and cups are arranged so that they tend to be forced together by pressure of propulsive gases of the rocket. A bladder, partially filled with fluid, is confined in each cup by its plug. Tubes connect either adjacent or diametrically opposite bladders; so that fluid may be displaced and exchanged between bladders as the nozzle is moved for steering the rocket. Hydraulic actuators may be interposed in tubes connecting diametrically opposite bladders for forcibly moving fluid from one to the other, and thereby move the nozzle. Alternatively, each bladder may be connected directly to a source of hydraulic fluid and be selectively inflated or deflated thereby for moving the nozzle. A gastight seal is provided between nozzle and case.

Experimentally determined rocket-exhaust flowfield in a constrictivetube launcher

Abstract: Pressure histories have been obtained during a flight test program in which a 6.0-in (15.2-cm) diameter rocket was launched from instrumented tube launchers whose cross section varied. Pressure measurements were used to define the flow mechanisms characterizing the underexpanded, supersonic rocket exhaust flow in the constrictive tube launcher. As the exhaust flow impinged on the constriction, the local pressure rose immediately, resulting in a pressure gradient in the annular region between the rocket and the launcher wall and, hence, the blowby flow. Later, when the rocket exhausted into the large-diameter forward tube, the flow was choked by the constrictive change in cross section and a normal shock wave was generated in the forward tube. Neither the geometry of the constriction nor the presence of vent ports significantly affected the pressure distribution in the launcher.

Directional antenna for a projectile or rocket detonator

Abstract: In a projectile or rocket having a metal outer shell and including a proximity or influence detonator which operates with electromagnetic waves, particularly according to the reflected beam principle, and a directional antenna with a rotationally symmetrical radiation diagram for said detonator, the antenna is constituted by a circular slot which is coaxial with the longitudinal axis of the projectile or rocket and the antenna is excited with a line or cavity resonator disposed in the projectile or rocket and connected between the detonator and the antenna.