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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Thrust vectoring systems

The design, fabrication, and testing of thrust vectorable ion optical systems capable of controlling the thrust direction from both 5- and 30-cm diameter ion thrusters is described. Both systems are capable of greater than 10 deg thrust deflection in any azimuthal direction. The 5-cm system is electrostatic and hence has a short response time and minimal power consumption. It has recently been tested for more than 7500 hours on an operational thruster. The 30-cm system is mechanical, has a response time of the order of 1 min, and consumes less than 0.3% of the total system input power at full deflection angle.

King, H. J.↗
NASA NTRS2011

Interstage Flammability Analysis Approach

The Interstage of the Ares I launch platform houses several key components which are on standby during First Stage operation: the Reaction Control System (ReCS), the Upper Stage (US) Thrust Vector Control (TVC) and the J-2X with the Main Propulsion System (MPS) propellant feed system. Therefore potentially dangerous leaks of propellants could develop. The Interstage leaks analysis addresses the concerns of localized mixing of hydrogen and oxygen gases to produce deflagration zones in the Interstage of the Ares I launch vehicle during First Stage operation. This report details the approach taken to accomplish the analysis. Specified leakage profiles and actual flammability results are not presented due to proprietary and security restrictions. The interior volume formed by the Interstage walls, bounding interfaces with the Upper and First Stages, and surrounding the J2-X engine was modeled using Loci-CHEM to assess the potential for flammable gas mixtures to develop during First Stage operations. The transient analysis included a derived flammability indicator based on mixture ratios to maintain achievable simulation times. Validation of results was based on a comparison to Interstage pressure profiles outlined in prior NASA studies. The approach proved useful in the bounding of flammability risk in supporting program hazard reviews.

Little, Jeffrey K.↗
NASA NTRS2018

Generic Control Allocation Toolbox for Preliminary Vehicle Design

This paper describes the development and application of a Generic Control Allocation Toolbox developed at NASA Langley Research Center (LGCAT) intended to aid engineers during the preliminary design phase of an aerospace vehicle. The static controllability space in the forms of a Theoretical Attainable Moment Set, Φ, or Theoretical Attainable Force Set, φ is difficult to visualize for modern vehicles with multiple types of redundant control effectors. The objective of LGCAT is to provide system engineers and designers early in the vehicle design phase with quick insights on how control effector parameters such as quantity, sizing, location, orientation, redundancy, etc., affect the overall controllability and other performance metrics. Having such information in hand allows system engineers to make more informed decisions on overall mission objectives such as performance vs. reliability vs. cost, etc. early in a vehicle design phase and reduce the number of iterations necessary in the design and analysis cycles. LGCAT can accept a variety of control effector types including aerodynamic surfaces, rotors, thrust vector control (TVC) engines, and reaction control systems (RCS). LGCAT is MATLAB based, user friendly, and is capable of performing the analysis in the Graphical User Interface (GUI) or script mode. Current add-on features include interfacing with engineering level codes such as Vehicle Sketch Pad (VSP) and generating the corresponding Φ and φ for an arbitrary vehicle design. These capabilities potentially make LGCAT an integral part of the preliminary design phase for any vehicle.

Pei, Jing↗
NASA NTRS1995

Design, analysis, and control of a large transport aircraft utilizing selective engine thrust as a backup system for the primary flight control

A study has been conducted to determine the capability to control a very large transport airplane with engine thrust. This study consisted of the design of an 800-passenger airplane with a range of 5000 nautical miles design and evaluation of a flight control system, and design and piloted simulation evaluation of a thrust-only backup flight control system. Location of the four wing-mounted engines was varied to optimize the propulsive control capability, and the time constant of the engine response was studied. The goal was to provide level 1 flying qualities. The engine location and engine time constant did not have a large effect on the control capability. The airplane design did meet level 1 flying qualities based on frequencies, damping ratios, and time constants in the longitudinal and lateral-directional modes. Project pilots consistently rated the flying qualities as either level 1 or level 2 based on Cooper-Harper ratings. However, because of the limited control forces and moments, the airplane design fell short of meeting the time required to achieve a 30 deg bank and the time required to respond a control input.

Gerren, Donna S.↗
NASA NTRS1999

Touchdown: The Development of Propulsion Controlled Aircraft at NASA Dryden

This monograph relates the important history of the Propulsion Controlled Aircraft project at NASA's Dryden Flight Research Center. Spurred by a number of airplane crashes caused by the loss of hydraulic flight controls, a NASA-industry team lead by Frank W. Burcham and C. Gordon Fullerton developed a way to land an aircraft safely using only engine thrust to control the airplane. In spite of initial skepticism, the team discovered that, by manually manipulating an airplane's thrust, there was adequate control for extended up-and-away flight. However, there was not adequate control precision for safe runway landings because of the small control forces, slow response, and difficulty in damping the airplane phugoid and Dutch roll oscillations. The team therefore conceived, developed, and tested the first computerized Propulsion Controlled Aircraft (PCA) system. The PCA system takes pilot commands, uses feedback from airplane measurements, and computes commands for the thrust of each engine, yielding much more precise control. Pitch rate and velocity feedback damp the phugoid oscillation, while yaw rate feedback damps the Dutch roll motion. The team tested the PCA system in simulators and conducted flight research in F-15 and MD-11 airplanes. Later, they developed less sophisticated variants of PCA called PCA Lite and PCA Ultralite to make the system cheaper and therefore more attractive to industry. This monograph tells the PCA story in a non- technical way with emphasis on the human aspects of the engineering and flic,ht-research effort. It thereby supplements the extensive technical literature on PCA and makes the development of this technology accessible to a wide audience.

Tucker, Tom↗
NASA NTRS2011

Solid Rocket Booster (SRB) - Evolution and Lessons Learned During the Shuttle Program

The Solid Rocket Booster (SRB) element integrates all the subsystems needed for ascent flight, entry, and recovery of the combined Booster and Motor system. These include the structures, avionics, thrust vector control, pyrotechnic, range safety, deceleration, thermal protection, and retrieval systems. This represents the only human-rated, recoverable and refurbishable solid rocket ever developed and flown. Challenges included subsystem integration, thermal environments and severe loads (including water impact), sometimes resulting in hardware attrition. Several of the subsystems evolved during the program through design changes. These included the thermal protection system, range safety system, parachute/recovery system, and others. Obsolescence issues occasionally required component recertification. Because the system was recovered, the SRB was ideal for data and imagery acquisition, which proved essential for understanding loads and system response. The three main parachutes that lower the SRBs to the ocean are the largest parachutes ever designed, and the SRBs are the largest structures ever to be lowered by parachutes. SRB recovery from the ocean was a unique process and represented a significant operational challenge; requiring personnel, facilities, transportation, and ground support equipment. The SRB element achieved reliability via extensive system testing and checkout, redundancy management, and a thorough postflight assessment process. Assembly and integration of the booster subsystems was a unique process and acceptance testing of reused hardware components was required for each build. Extensive testing was done to assure hardware functionality at each level of stage integration. Because the booster element is recoverable, subsystems were available for inspection and testing postflight, unique to the Shuttle launch vehicle. Problems were noted and corrective actions were implemented as needed. The postflight assessment process was quite detailed and a significant portion of flight operations. The SRBs provided fully redundant critical systems including thrust vector control, mission critical pyrotechnics, avionics, and parachute recovery system. The design intent was to lift off with full redundancy. On occasion, the redundancy management scheme was needed during flight operations. This paper describes some of the design challenges, how the design evolved with time, and key areas where hardware reusability contributed to improved system level understanding.

Kanner, Howard S.↗
NASA NTRS2011

Solid Rocket Booster (SRB) Flight System Integration at Its Best

The Solid Rocket Booster (SRB) element integrates all the subsystems needed for ascent flight, entry, and recovery of the combined Booster and Motor system. These include the structures, avionics, thrust vector control, pyrotechnic, range safety, deceleration, thermal protection, and retrieval systems. This represents the only human-rated, recoverable and refurbishable solid rocket ever developed and flown. Challenges included subsystem integration, thermal environments and severe loads (including water impact), sometimes resulting in hardware attrition. Several of the subsystems evolved during the program through design changes. These included the thermal protection system, range safety system, parachute/recovery system, and others. Because the system was recovered, the SRB was ideal for data and imagery acquisition, which proved essential for understanding loads, environments and system response. The three main parachutes that lower the SRBs to the ocean are the largest parachutes ever designed, and the SRBs are the largest structures ever to be lowered by parachutes. SRB recovery from the ocean was a unique process and represented a significant operational challenge; requiring personnel, facilities, transportation, and ground support equipment. The SRB element achieved reliability via extensive system testing and checkout, redundancy management, and a thorough postflight assessment process. However, the in-flight data and postflight assessment process revealed the hardware was affected much more strongly than originally anticipated. Assembly and integration of the booster subsystems required acceptance testing of reused hardware components for each build. Extensive testing was done to assure hardware functionality at each level of stage integration. Because the booster element is recoverable, subsystems were available for inspection and testing postflight, unique to the Shuttle launch vehicle. Problems were noted and corrective actions were implemented as needed. The postflight assessment process was quite detailed and a significant portion of flight operations. The SRBs provided fully redundant critical systems including thrust vector control, mission critical pyrotechnics, avionics, and parachute recovery system. The design intent was to lift off with full redundancy. On occasion, the redundancy management scheme was needed during flight operations. This paper describes some of the design challenges and technical issues, how the design evolved with time, and key areas where hardware reusability contributed to improved system level understanding.

Wood, T. David↗
NASA NTRS2009

Adaptive Control of a Transport Aircraft Using Differential Thrust

The paper presents an adaptive control technique for a damaged large transport aircraft subject to unknown atmospheric disturbances such as wind gust or turbulence. It is assumed that the damage results in vertical tail loss with no rudder authority, which is replaced with a differential thrust input. The proposed technique uses the adaptive prediction based control design in conjunction with the time scale separation principle, based on the singular perturbation theory. The application of later is necessitated by the fact that the engine response to a throttle command is substantially slow that the angular rate dynamics of the aircraft. It is shown that this control technique guarantees the stability of the closed-loop system and the tracking of a given reference model. The simulation example shows the benefits of the approach.

Stepanyan, Vahram↗
NASA NTRS1974

Verification test results of Apollo stabilization and control systems during undocked operations

The results are presented of analysis and simulation testing of both the Skylark 1 reaction control system digital autopilot (RCS DAP) and the thrust vector control (TVC) autopilot for use during the undocked portions of the Apollo/Soyuz Test Project Mission. The RCS DAP testing was performed using the Skylab Functional Simulator (SLFS), a digital computer program capable of simulating the Apollo and Skylab autopilots along with vehicle dynamics including bending and sloshing. The model is used to simulate three-axis automatic maneuvers along with pilot controlled manual maneuvers using the RCS DAP. The TVC autopilot was tested in two parts. A classical stability analysis was performed on the vehicle considering the effects of structural bending and sloshing when under control of the TVC autopilot. The time response of the TVC autopilot was tested using the SLFS. Results indicate that adequate performance stability margins can be expected for the CSM/DM configuration when under the control of the Apollo control systems tested.

Copeland, E. L.↗
NASA NTRS1991

A simulation evaluation of a four-engine jet transport using engine thrust modulation for flightpath control

The use of throttle control laws to provide adequate flying qualities for flight path control in the event of a total loss of conventional flight control surface use was evaluated. The results are based on a simulation evaluation by transport research pilots of a B-720 transport with visual display. Throttle augmentation control laws can provide flight path control capable of landing a transport-type aircraft with up to moderate levels of turbulence. The throttle augmentation mode dramatically improves the pilots' ability to control flight path for the approach and landing flight condition using only throttle modulation. For light turbulence, the average Cooper-Harper pilot rating improved from unacceptable to acceptable (a pilot rating improvement of 4.5) in going from manual to augmented control. The low frequency response characteristics of the engines require a considerably different piloting technique. The various techniques used by the pilot resulted in considerable scatter in data. Many pilots readily adapted to a good piloting technique while some had difficulty. A new viable approach is shown to provide independent means of redundancy of transport aircraft flight path control.

Gilyard, Glenn B.↗
NASA NTRS1991

A simulation evaluation of a four-engine jet transport using engine thrust modulation for flightpath control

The use of throttle control laws to provide adequate flying qualities for flightpath control in the event of a total loss of conventional flight control surface use was evaluated. The results are based on a simulation evaluation by transport research pilots of a B-720 transport with visual display. Throttle augmentation control laws can provide flightpath control capable of landing a transport-type aircraft with up to moderate levels of turbulence. The throttle augmentation mode dramatically improves the pilots' ability to control flightpath for the approach and landing flight condition using only throttle modulation. For light turbulence, the average Cooper-Harper pilot rating improved from unacceptable to acceptable (a pilot rating improvement of 4.5) in going from manual to augmented control. The low frequency response characteristics of the engines require a considerably different piloting technique. The various techniques used by the pilots resulted in considerable scatter in the data. Many pilots readily adapted to a good piloting technique while some has difficulty. The research demonstrates a new and viable approach to providing an independent means of redundancy or increasing the redundancy capability of transport aircraft flightpath control.

Gilyard, Glenn B.↗
NASA NTRS1993

Aerodynamic flight control to increase payload capability of future launch vehicles

In this report, we provide some examples of French, Russian, Chinese, and Japanese launch vehicles that have utilized fins in their designs. Next, the aerodynamic design of the fins is considered in Section 3. Some comments on basic static stability and control theory are followed by a brief description of an aerodynamic characteristics prediction code that was used to estimate the characteristics of a modified NLS 1.5 Stage vehicle. Alternative fin designs are proposed and some estimated aerodynamic characteristics presented and discussed. Also included in Section 3 is a discussion of possible methods of enhancement of the aerodynamic efficiency of fins, such as vortex generators and jet flaps. We consider the construction of fins for launch vehicles in Section 4 and offer an assessment of the state-of-the-art in the use of composites for aerodynamic control surfaces on high speed vehicles. We also comment on the use of smart materials for launch vehicle fins. The dynamic stability and control of a launch vehicle that utilizes both thrust vector control (engine nozzle gimballing) and movable fins is the subject addressed in Section 5. We give a short derivation of equations of motion for a launch vehicle moving in a vertical plane above a spherical earth, discuss the use of a gravity-turn nominal trajectory, and give the form of the period equations linearized about such a nominal. We then consider feedback control of vehicle attitude using both engine gimballing and fin deflection. Conclusions are stated and recommendations made in Section 6. An appendix contains aerodynamic data in tabular and graphical formats.

Cochran, John E., Jr.↗
NASA NTRS1998

Controller Design for EMA in TVC Incorporating Force Feedback

The objective of this research was to develop control schemes and control design procedures for electromechanical actuators (EMA) in thrust vector control (TVC) applications. For a variety of reasons, there is a tendency within the aerospace community to use electromechanical actuators in applications where hydraulics have traditionally been employed. TVC of rocket engines is one such application. However, there is considerable research, development, and testing to be done before EMA will be accepted by the community at large for these types of applications. Besides the development of design procedures for the basic position controller, two major concerns are dealt with in this research by incorporating force feedback: 1) the effects of resonance on the performance of EMA-TVC-rocket-engine systems, and 2) the effects of engine start transients on EMA. This report only highlights the major contributions of this research.

Schinstock, Dale E.↗