Engineering topics
Publications and source records attributed to Berry, R. L..
The Cassini Spacecraft will be launched on an expedition to Saturn in October 1997. The mission is an eleven year operation, the first seven years traveling to Saturn via a combination of propulsion burns and Venus-Venus-Earth-Jupiter gravity-assist, and the remaining four years orbiting Saturn while exploring the planet, it's moons, rings, and nearby icy satellites.
Commonly-used locomotive trucks tested to study and improve ride safety. Federal Railroad Administration and National Aeronautics and Space Administration jointly initiated program to study locomotive truck dynamics to improve operation safety. Final report summarizes program and truck and component tests.
This report presents the results of a study to develop an analytical model capable of predicting the dynamic interaction forces on the Shuttle External Tank, due to large amplitude propellant slosh during RTLS separation. The report details low-g drop tower and KC-135 test programs that were conducted to investigate propellant reorientation during RTLS. In addition, the development of a nonlinear finite element slosh model (LAMPS2, two dimensional, and one LAMPS3, three dimensional) is presented. Correlation between the model and test data is presented as a verification of the modeling approach.
Report describes analytical approach to question of operational safety for six-axle locomotives. Essential mathematical elements are locomotive model with corresponding data on suspension characteristics, method of track-defect characterization, and quantitative measures for characterizing operational safety.
Locomotive mechanical characteristics, track perturbations, and operational characteristics involving experimentally determined suspension system parameters are analyzed. Suspension bearings, shock absorbers, pads, and two- and three- axle trucks are comparatively evaluated with respect to locomotive design.
The development of a multiple-mass, nonlinear, finite-element analytical model - the Large AMplitude Propellant Slosh model (LAMPS) in two- and three-dimensional versions, is described. The model is used in predicting the forces on the Space Shuttle external tank caused by large amplitude motion of propellant fluid. Comparisons between measured propellant reorientation forces and those predicted by the LAMPS models are presented, and it is concluded that the model provides a cost effective, experimentally verified approach to a complicated nonlinear problem.
This paper presents the results of a study to develop an analytical model capable of predicting the forces acting on a tank caused by large-amplitude propellant motion. This effort contributed to an analysis of the influence of propellant dynamics on separation of the External Tank from the space shuttle orbiter. This paper is concerned with an experimental investigation that aided in development and verification of the analytical model. A scaling approach was developed that allowed the liquid motion to be simulated in subscale tanks. Liquid reorientation forces were measured using two test systems. One operated in the low-gravity environment produced in a drop tower and the second operated aboard the KC-135 'zero-g' test aircraft. The manner of liquid motion, influence of various factors, and the measured forces are discussed.
Space shuttle propellant dynamics during ET/Orbiter separation in the RTLS (return to launch site) mission abort sequence were investigated in a test program conducted in the NASA KC-135 "Zero G" aircraft using a 1/10th-scale model of the ET LOX Tank. Low-g parabolas were flown from which thirty tests were selected for evaluation. Data on the nature of low-g propellant reorientation in the ET LOX tank, and measurements of the forces exerted on the tank by the moving propellent will provide a basis for correlation with an analytical model of the slosh phenomenon.
Thirty sets of test data selected from the 89 low-g aircraft tests flown by NASA KC-135 zero-g aircraft are listed in tables with their accompanying test conditions. The data for each test consists of the time history plots of digitalized data (in engineering units) and the time history plots of the load cell data transformed to the tank axis system. The transformed load cell data was developed for future analytical comparisons; therefore, these data were transformed and plotted from the time at which the aircraft Z axis acceleration passed through l-g. There are 14 time history plots per test condition. The contents of each plot is shown in a table.
During the abort sequence, the ET and orbiter separate under aerodynamic loading, with propellant remaining in the ET. The separation event included a seven second decelerating coast period during which the residual propellant accelerates relative to the ET/orbiter. At separation, ET clearance was primarily provided by aerodynamics acting on the ET to move it away. The motion of the propellant, primarily LOX, significantly influenced the resulting ET motion and could cause the ET to recontact the orbiter. A test program was conducted involving thirty-two drops with 1/60th scale models of the ET LOX tank. The objective was to acquire data on the nature of low g propellant reorientation, in the ET LOX tank, and to measure the forces exerted on the tank by the moving propellant.
A test program was conducted involving forty-five drops of liquid propellant in instrumented tanks. Biaxial, low-g accelerations were applied to the model propellant tanks during free-fall testing, and forces exerted during liquid reorientation were measured and recorded. High speed photographic records of the liquid reorientation were also made. The test data was used to verify a mechanical analog which portrays the liquid as a point mass moving on an ellipsoidal constraint surface. The mechanical analog was coded into two FORTRAN 4 digital computer programs. Results showed excellent correlation between test data and analytical predictions of reorientation forces and liquid center of mass motion, verifying the basic analytical approach.
The results are presented of a twofold study of transient liquid motion such as that which will be experienced during orbital maneuvers by space tug. A test program was conducted in a low-g test facility involving twenty-two drops. Biaxial, low-g accelerations were applied to an instrumented, model propellant tank during free-fall testing, and forces exerted during liquid reorientation were measured and recorded. Photographic records of the liquid reorientation were also made. The test data were used to verify a mechanical analog which portrays the liquid as a point mass moving on an ellipsoidal constraint surface. The mechanical analog was coded into a FORTRAN IV digital computer program: LAMPS, Large AMPlitude Slosh. Test/analytical correlation indicates that the mechanical analog is capable of predicting the overall force trends measured during testing.
Evaluation of effects of vibrational multiple frequency forcing functions is discussed. Computer program for developing vibrational transfer functions is described. Possible applications of computer program are enumerated.
Apollo 11 lunar landing mission planning, control and evaluation of launch window and translunar, lunar parking orbit and transearth trajectories
Real time targeting for Apollo lunar orbit insertion maneuver burn, discussing impulsive maneuvers for flight control
Real time targeting for Apollo lunar orbit insertion maneuver burn, discussing impulsive maneuvers for flight control