PC programs for the prediction of the linear stability behavior of liquid propellant propulsion systems and application to current MSFC rocket engine test programs, volume 1

Research on propulsion stability (chugging and acoustic modes), and propellant valve control was investigated. As part of the activation of the new liquid propulsion test facilities, it is necessary to analyze total propulsion system stability. To accomplish this, several codes were built to run on desktop 386 machines. These codes enable one to analyze the stability question associated with the propellant feed systems. In addition, further work was adapted to this computing environment and furnished along with other codes. This latter inclusion furnishes those interested in high frequency oscillatory combustion behavior (that does not couple to the feed system) a set of codes for study of proposed liquid rocket engines

Definition of ground test for verification of large space structure control

Directions regarding the analytical models were received. A counter balance arm with weights was added at the top of the ASTROMAST to offset the arm with the gimbals. In addition to this model, three more models were requested from MSFC: structure as in the revised model with the addition of lumped masses at bays 46 and 91 of the ASTROMAST; cantilevered cruciform structure with lumped masses at bays 46 and 91, and an all up cruciform structure with lumped masses at bays 46 and 91. Figures for each model and their corresponding natural frequencies and general mode shapes associated with these frequencies are included. The drawbar in use in the cruciform models must be incorporated into the antenna and ASTROMAST models. The total tensile load carrying capability of the ASTROMAST is approximately 840 pounds

Definition of ground test for Large Space Structure (LSS) control verification

An overview for the definition of a ground test for the verification of Large Space Structure (LSS) control is given. The definition contains information on the description of the LSS ground verification experiment, the project management scheme, the design, development, fabrication and checkout of the subsystems, the systems engineering and integration, the hardware subsystems, the software, and a summary which includes future LSS ground test plans. Upon completion of these items, NASA/Marshall Space Flight Center will have an LSS ground test facility which will provide sufficient data on dynamics and control verification of LSS so that LSS flight system operations can be reasonably ensured

NASA-VCOSS dynamic test facility

The Large Space Structure Ground Test Facility under development at the NASA Marshall Space Flight Center in Huntsville, Alabama is described. The Ground Test Facility was established initially to test experimentally the control system to be used on the Solar Array flight Experiment. The structural dynamics of the selected test article were investigated, including the fidelity of the associated mathematical model. The facility must permit the investigation of structural dynamics phenomena and be able to evaluate candidate attitude control and vibration suppression techniques

High temperature superconductor materials and applications

Research on processing methods leading to a significant enhancement in the critical current densities (Jc) and the critical temperature (Tc) of high temperature superconducting in thin bulk and thin film forms. The fabrication of important devices for NASA unique applications (sensors) is investigated

Distributed control using linear momentum exchange devices

MSFC has successfully employed the use of the Vibrational Control of Space Structures (VCOSS) Linear Momentum Exchange Devices (LMEDs), which was an outgrowth of the Air Force Wright Aeronautical Laboratory (AFWAL) program, in a distributed control experiment. The control experiment was conducted in MSFC's Ground Facility for Large Space Structures Control Verification (GF/LSSCV). The GF/LSSCV's test article was well suited for this experiment in that the LMED could be judiciously placed on the ASTROMAST. The LMED placements were such that vibrational mode information could be extracted from the accelerometers on the LMED. The LMED accelerometer information was processed by the control algorithms so that the LMED masses could be accelerated to produce forces which would dampen the vibrational modes of interest. Experimental results are presented showing the LMED's capabilities

Development and use of a linear momentum exchange device

In 1981 the Marshall Space Flight Center (MSFC) began establishing an inhouse facility for testing control concepts to be applied to Large Space Structures (LSS). The original concept called for a long flexible beam suspended from the ceiling by a low friction support system. The lower end of the beam was to be mounted to the Advanced Gimbal System (AGS). Analysis and system engineering soon showed that a more tenable design would be where the whole system was inverted, i.e., the AGS hung from the ceiling with the beam hanging down from it. While this configuration, augmented by a base excitation table (RET) was being built, an ASTROMAST obtained from the Jet Propulsion Laboratory was extended, analyzed and tested. From that basic configuration was evolved the cruciform, VCOSS and ACES configurations as shown. The addition of the cruciform added low frequency nested modes and the additional instrument package at the tip contains gyros to monitor tip motion

Definition of ground test for verification of large space structure control

Control theory and design, dynamic system modelling, and simulation of test scenarios are the main ideas discussed. The overall effort is the achievement at Marshall Space Flight Center of a successful ground test experiment of a large space structure. A simplified planar model of ground test experiment of a large space structure. A simplified planar model of ground test verification was developed. The elimination from that model of the uncontrollable rigid body modes was also examined. Also studied was the hardware/software of computation speed

Propulsion stability codes for liquid propellant propulsion systems developed for use on a PC computer

Research into component modeling and system synthesis leading to the analysis of the major types of propulsion system instabilities and the characterization of various components characteristics are presented. Last year, several programs designed to run on a PC were developed for Marshall Space Flight Center. These codes covered the low, intermediate, and high frequency modes of oscillation of a liquid rocket propulsion system. No graphics were built into these programs and only simple piping layouts were supported. This year's effort was to add run time graphics to the low and intermediate frequency codes, allow new types of piping elements (accumulators, pumps, and split pipes) in the low frequency code, and develop a new code for the PC to generate Nyquist plots

Advanced electric motor technology flux mapping

Design of electric motors which fulfill the needs of Thrust Vector Control (TVC) actuators used in large rocket propelled launch vehicles is covered. To accomplish this end the methodology of design is laid out in some detail. In addition a point design of a motor to fulfill the requirements of a certain actuator specified by MSFC is accomplished and reported upon. In the course of this design great stress has been placed on ridding the actuator of internally generated heat. To conduct the heat out of the motor use is made of the unique properties of the in house MSFC designed driving electronics. This property is that as along as they are operated in a quasi-linear mode the electronics nullify the effects of armature inductance as far as the phase of the armature current versus the rotor position is concerned. Actually the additional inductance due to the extended end turns in this design is of benefit because in the shorted armature failure mode the armature current in the fault (caused by the rotor flux sweeping past the armature) is diminished at a given rotor speed when compared to a more conventional motor with lower inductance. The magnetic circuit is analyzed using electromagnetic finite element methods