Engineering Papers⌕ Search

Engineering topics

Powell, R. W.

Publications and source records attributed to Powell, R. W..

47 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Effects of modifications to the space shuttle entry guidance and control systems

A nonlinear six degree of freedom entry simulation study was conducted to identify space shuttle guidance and control system software modifications which reduce the control system sensitivity to the guidance system sampling frequency. Several modifications which eliminated the control system sensitivity and associated control limit cycling were examined. The result of the modifications was a reduction in required reaction control system fuel.

Powell, R. W.↗
NASA NTRS1976

Effect of probe configuration on radiative heating during Jovian entry

The radiative heating to the probe's surface and the effects of the recession of the heat shield caused by this heating are analyzed for five initial probe configurations for a Jovian entry. The initial configurations are spherically capped, conical bodies and hyperboloids. The results show that severe blunting of the nose region occurs for all configurations due to ablation of the heat shield caused by the large radiative heating rates. Recession at the nose region can possibly cause a concavity at the stagnation point. Furthermore, the recession of the heat shield, especially for the spherically capped, conical bodies, will be underpredicted if the change in the probe's shape during the entry is neglected in an analysis.

Sutton, K.↗
NASA NTRS1976

Space Shuttle Orbiter entry guidance and control system sensitivity analysis

An approach has been developed to determine the guidance and control system sensitivity to off-nominal aerodynamics for the Space Shuttle Orbiter during entry. This approach, which uses a nonlinear six-degree-of-freedom interactive, digital simulation, has been applied to both the longitudinal and lateral-directional axes for a portion of the orbiter entry. Boundary values for each of the aerodynamic parameters have been identified, the key parameters have been determined, and system modifications that will increase system tolerance to off-nominal aerodynamics have been recommended. The simulations were judged by specified criteria and the performance was evaluated by use of key dependent variables. The analysis is now being expanded to include the latest shuttle guidance and control systems throughout the entry speed range.

Stone, H. W.↗
NASA NTRS1975

Effects of Control Hysteresis on the Space Shuttle Orbiter's Entry

There are six degree-of-freedom simulations of the space shuttle orbiter entry with aerodynamic control hysteresis conducted on the NASA Langley Research Center interactive simulator known as the Automatic Reentry Flight Dynamics Simulator. These were performed to determine if the presence of aerodynamic control hysteresis would endanger the mission, either by making the vehicle unable to maintain proper attitude for a safe entry, or by increasing the amount of the reaction control system's fuel consumption beyond that carried.

Powell, R. W.↗
NASA NTRS1974

Investigation of abort procedures for space shuttle-type vehicles

An investigation has been made of abort procedures for space shuttle-type vehicles using a point mass trajectory optimization program known as POST. This study determined the minimum time gap between immediate and once-around safe return to the launch site from a baseline due-East launch trajectory for an alternate space shuttle concept which experiences an instantaneous loss of 25 percent of the total main engine thrust.

Powell, R. W.↗
NASA NTRS1974

Supersonic performance, stability and control characteristics of a 0.01875 scale model Rockwell International 089B-139B orbiter configuration (LA8C)

An investigation was made in the Langley Unitary Plan Wind Tunnel at Mach numbers of 1.9 and 2.86 to study the supersonic aerodynamic characteristics of a Rockwell International shuttle orbiter configuration. Tests were made at a Reynolds number of 1.5 million per foot with an angle-of-attack range of minus 4 to 28 deg and sideslip variations of minus 6 to 8 deg. The effects of elevon and aileron deflections were investigated.

Powell, R. W.↗
NASA NTRS1973

Hypersonic performance, stability and control characteristics of a .0075 scale model Rockwell International 089B-139B orbiter configuration

An investigation was made in the Langley Continuous Flow Hypersonic Tunnel at a Mach number of 10.3 to study the hypersonic aerodynamic characteristics of a Rockwell International shuttle orbiter configuration. Tests were made at a Reynolds number of 790,000 x 106 based on body length with an angle-of-attack range of 10 to 35 deg and sideslip variations of +1 to -9 deg. The effects of elevon and body flap deflection were investigated.

Powell, R. W.↗
NASA NTRS1972

Grumman H-33 space shuttle orbiter aerodynamic and handling-qualities study

A study of a representative delta-wing orbiter, the Grumman H-33, that utilized external-hydrogen tanks has been completed. The study encompassed a detailed wind-tunnel program from subsonic to hypersonic speeds, analyses of the data, and the calculation and assessment of the orbiter handling qualities using the most aft center-of-gravity locations anticipated during entry and approach.

Rainey, R. W.↗
NASA NTRS1971

Fiscal output data produce versatile graphic-numeric charts

Refined computerized plotting system produces low-cost graphic-numeric charts that illustrate fiscal data on monthly incremental or cumulative basis, or both. Output is in the form of hard copy or microfilm, or visual-aid transparencies prepared from hard copy for rapid management status presentations.

Powell, R. W.↗