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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 235 records · Page 13

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NASA NTRS1993

Lightweight Boom For Rescue Helicopter

Telescoping boom and associated mechanisms attached to helicopter aid rescue operations by extending lifeline beyond sweep of main rotor. Pilot observes rescuee and control position of helicopter more effectively than if rescuee directly below and hidden from pilot's view. Rescuee outside downdraft of rotor, which is often powerful enough to blow away or submerge someone in water. Used for marine or land operations. Boom thin and lightweight because it need not support weight of rescuee. Lifeline pulls away from boom after secured around rescuee, who is lifted directly into cabin by winch. Potential application for in situ erection of telescopic space structures.

Haslim, Leonard A.↗

NASA NTRS2017

The Impacts of Rising Temperatures on Aircraft Takeoff Performance

Steadily rising mean and extreme temperatures as a result of climate change will likely impact the air transportation system over the coming decades. As air temperatures rise at constant pressure, air density declines, resulting in less lift generation by an aircraft wing at a given airspeed and potentially imposing a weight restriction on departing aircraft. This study presents a general model to project future weight restrictions across a fleet of aircraft with different takeoff weights operating at a variety of airports. We construct performance models for five common commercial aircraft and 19 major airports around the world and use projections of daily temperatures from the CMIP5 model suite under the RCP 4.5 and RCP 8.5 emissions scenarios to calculate required hourly weight restriction. We find that on average, 10 - 30% of annual flights departing at the time of daily maximum temperature may require some weight restriction below their maximum takeoff weights, with mean restrictions ranging from 0.5 to 4% of total aircraft payload and fuel capacity by mid- to late century. Both mid-sized and large aircraft are affected, and airports with short runways and high temperatures, or those at high elevations, will see the largest impacts. Our results suggest that weight restriction may impose a non-trivial cost on airlines and impact aviation operations around the world and that adaptation may be required in aircraft design, airline schedules, and/or runway lengths.

air transportation system↗

NASA NTRS1972

Simulation study of the lift roll coupling problem for hovering VTOL aircraft

The effects of lift-roll coupling on the handling qualities of hovering VTOL aircraft using differential thrust for roll control were assessed in a piloted simulation study in the Ames six-degrees-of-freedom motion simulator. The configuration tested has three vertical thrust sources, one on the roll axis and two laterally displaced from the roll axis, with a thrust distribution of 25%/50%/25%. The outboard thrust sources were modulated to provide roll control whereas all three provided height control. Maximum thrust-to-weight ratio was varied together with a coupling parameter that combined roll-inertia, weight, and engine location. Results showed that handling qualities are affected not only by the occurrence of lift-roll coupling (dependent on both variables) but also by the severity of the coupling (dependent on the coupling parameter alone). However, the advantages of differential thrust for control can be retained with careful design.

Jacobsen, R. A.↗

NASA NTRS1971

Mars surface sample return missions via solar electric propulsion

The characteristics and capabilities are described of solar electric propulsion (SEP) for performing Mars Surface Sample Return (MSSR) missions. The scope of the study emphasizes trajectory/payload analysis and the comparison of mission/system tradeoff options. The MSSR mission is examined only for the 1981-82 launch opportunity. Several other study constraints which bear directly on the results obtained are: (1) return samples in the range 5-25 kg, (2) use of lifting (offset C.G.) atmospheric entry at Mars which allows a low ratio (1.25) of entry weight to landed weight, and (3) rendezvous and docking in Mars orbit. Major results of the study are presented as performance curves of earth departure mass versus sample size for a number of different mission/system options. These options represent a spectrum of trip time, launch vehicle capability, combinations of low-thrust and ballistic maneuvers, chemical retro type, and earth recovery mode.

Spadoni, D. J.↗

NASA NTRS1976

Technology outlook for aviation

Growth projections for aviation technology are put forth for a quarter-century ahead. Three main trends envisaged are towards: great efficiency and economy and longer range and endurance for subsonic aircraft; new generations of short-range fixed-wing craft and rotorcraft with versatile applicability; supersonic and hypersonic speeds. Improvements in lift/drag ratio, specific fuel consumption, structural weight factor, aerodynamic improvements (laminar flow control, increased wing aspect ratio, drag reduction for specified lift, propulsion efficiency, higher bypass ratios, composite structures) are discussed along with V/STOL, controllable twist rotors, circulation control rotors, variable-cycle engines, and higher structural efficiencies.

Roberts, L.↗

NASA NTRS1985

Study of an efficient long-range Mach 2.7 supersonic transport configuration concept

A long range Mach 2.7 supersonic transport configuration concept was studied utilizing linear theory methods. The configuration was sized to carry 290 passengers 6,000 nautical miles nonstop. The final configuration has a maximum takeoff gross weight of 687,200 pounds, a wing loading of 69.8 lbf/sq.ft. and a thrust weight ratio of .278. The most significant result is that a significantly improved trimmed maximum lift drag ratio of 11.04 can be obtained for a supersonic transport at Mach 2.62 and 55,000 feet.

Gall, P. D.↗

NASA NTRS1990

Advanced Rotorcraft Transmission Program

The U.S. Army/NASA Advanced Rotorcraft Transmission (ART) program is charged with developing and demonstrating a light, quiet, and durable drivetrain for next-generation rotorcraft in two classes: a 10,000-20,000 Future Attack Air Vehicle capable of both tactical ground support and air-to-air missions, and a 60,000-80,000 lb Advanced Cargo Aircraft, for heavy-lift field-support operations. Specific ART objectives encompass a 25-percent reduction in drivetrain weight, a 10-dB noise level reduction at the transmission source, and the achievement of a 5000-hr MTBF. Four candidate drivetrain systems have been carried to a conceptual design stage, together with projections of their mission performance and life-cycle costs.

Bill, Robert C.↗

NASA NTRS1993

Portable Lifting Seat

Portable lifting machine assists user in rising from seated position to standing position, or in sitting down. Small and light enough to be carried like briefcase. Used on variety of chairs and benches. Upholstered aluminum box houses mechanism of lifting seat. Springs on outer shaft-and-arm subassembly counterbalance part of user's weight to assist motor.

Weddendorf, Bruce↗

NASA NTRS2012

One Engine Inoperative (OEI) and Autorotation For Heavy Lift Rotorcraft Systems

Federal Aviation Administration will certainly require the Heavy Lift Rotorcraft to be operated under Category A performance and operations requirements. Because of the weight, no operation will be allowed except Category A according to FAA Part 29.1(c). This means that any where along the flight path, the aircraft must be able to land safely following an engine failure or continue flight. A repeatable flight profile must be developed and executed to ensure that the aircraft can be safely landed or flown away depending on its location on the flight profile. This means that there will be no Height-Velocity testing required as is currently required for Part 29 Category B. Since all the configurations shown to date are different than existing rotorcraft, each type would have to develop their individual requirements under existing special conditions FAA Part 21.17(b). This means the FAA will take the opportunity to negotiate additional requirements or change requirements to ensure safety. For example, since the tiltrotor did not fit normal rotorcraft category, new rules were negotiated between the applicant and the FAA. As a result of this negotiation, performance requirements for Category A were increased. The rules were written in terms of guaranteed performance instead of Category A requirements. Detailed discussion will follow later. The proposed tiltrotor would likely follow along with the current tiltrotor rules with the possibility of increase Category A performance requirements. Compounding with addition of wing and auxiliary thrust to both the tandem and coaxial rotor would result in new special condition aircraft. To my knowledge, no compound tandem or compound coaxial rotor has ever been certified by FAA.

Wood, Tom↗

NASA NTRS1990

A study of sonic boom overpressure trends with respect to weight, altitude, Mach number, and vehicle shaping

This paper presents and discusses trends in nose shock overpressure generated by two conceptual Mach 2.0 configurations. One configuration was designed for high aerodynamic efficiency, while the other was designed to produce a low boom, shaped-overpressure signature. Aerodynamic lift, sonic boom minimization, and Mach-sliced/area-rule codes were used to analyze and compute the sonic boom characteristics of both configurations with respect to cruise Mach number, weight, and altitude. The influence of these parameters on the overpressure and the overpressure trends are discussed and conclusions are given.

Needleman, Kathy E.↗

NASA NTRS1996

Application of pneumatic lift and control surface technology to advanced transport aircraft

The application of pneumatic (blown) aerodynamic technology to both the lifting and the control surfaces of advanced transport aircraft can provide revolutionary changes in the performance and operation of these vehicles, ranging in speed regime from Advanced Subsonic Transports to the High Speed Civil Transport, and beyond. This technology, much of it based on the Circulation Control Wing blown concepts, can provide aerodynamic force augmentations of 80 to 100 (i.e., return of 80-100 pounds of force per pound of input momentum from the blowing jet). This can be achieved without use of external mechanical surfaces. Clever application of this technology can provide no-moving-part lifting surfaces (wings/tails) integrated into the control system to greatly simplify aircraft designs while improving their aerodynamic performance. Lift/drag ratio may be pneumatically tailored to fit the current phase of the flight, and takeoff/landing performance can be greatly improved by reducing ground roll distances and liftoff/touchdown speeds. Alternatively, great increases in liftoff weights and payloads are possible, as are great reductions in wing and tail planform size, resulting in optimized cruise wing designs. Furthermore, lift generation independent of angle of attack provides much promise for increased safety of flight in the severe updrafts/downdrafts of microbursts and windshears, which is further augmented by the ability to sustain flight at greatly reduced airspeeds. Load-tailored blown wings can also reduce tip vorticity during highlift operations and the resulting vortex wake hazards near terminal areas. Reduced noise may also be possible as these jets can be made to operate at low pressures. The planned presentation will support the above statements through discussions of recent experimental and numerical (CFD) research and development of these advanced blown aerodynamic surfaces, portions of which have been conducted for NASA. Also to be presented will be predicted performance of advanced transports resulting from these devices. Suggestions will be presented for additional innovative high-payoff research leading to further confirmation of these concepts and their application to advanced efficient commercial transport aircraft.

Englar, Robert J.↗

NASA NTRS1977

Application of powered lift and mechanical flap concepts for civil short-haul transport aircraft design

The objective of this paper is to determine various design and performance parameters, including wing loading and thrust loading requirements, for powered-lift and mechanical flap conceptual aircraft constrained by field length and community noise impact. Mission block fuel and direct operating costs (DOC) were found for optimum designs. As a baseline, the design and performance parameters were determined for the aircraft using engines without noise suppression. The constraint of the 90 EPNL noise contour being less than 2.6 sq km (1.0 sq mi) in area was then imposed. The results indicate that for both aircraft concepts the design gross weight, DOC, and required mission block fuel decreased with field length. At field lengths less than 1100 m (3600 ft) the powered lift aircraft had lower DOC and block fuel than the mechanical flap aircraft but produced higher unsuppressed noise levels. The noise goal could easily be achieved with nacelle wall treatment only and thus resulted in little or no performance or weight penalty for all studied aircraft.

Conlon, J. A.↗

NASA NTRS1983

A lifting surface theory in rotational flow

The partial differential equation for small disturbance steady rotational flow in three dimensions is solved through an integral equation approach. The solution is obtained by using the method of weighted residuals. Specific applications are directed to wings in nonuniform subsonic parallel streams with velocity varying in vertical and spanwise directions and to airfoils in nonuniform freestream. Comparison with limited known results indicates that the present method is reasonably accurate. Numerical results for the lifting pressure of airfoil, lift, induced drag, and pitching moments of airfoil, lift, induced drag, and pitching moments of elliptic, rectangular, and delta wings in a jet, wake, or monotonic sheared stream are presented. It is shown that, in addition to the effect of local dynamic pressures, a positive velocity gradient tends to enhance the lift.

Shiau, M. J.↗

NASA NTRS1973

Takeoff certification considerations for large subsonic and supersonic transport airplanes using the Ames flight simulator for advanced aircraft

Data for use in development of takeoff airworthiness standards for new aircraft designs such as the supersonic transport (SST) and the large wide-body subsonic jet transport are provided. An advanced motion simulator was used to compare the performance and handling characteristics of three representative large jet transports during specific flight certification tasks. Existing regulatory constraints and methods for determining rotation speed were reviewed, and the effects on takeoff performance of variations in rotation speed, pitch attitude, and pitch attitude rate during the rotation maneuver were analyzed. A limited quantity of refused takeoff information was obtained. The aerodynamics, wing loading, and thrust-to-weight ratio of the subject SST resulted in takeoff speeds limited by climb (rather than lift-off) considerations. Take-off speeds based on U.S. subsonic transport requirements were found unacceptable because of the criticality of rotation-abuse effects on one-engine-inoperative climb performance. Adequate safety margin was provided by takeoff speeds based on proposed Anglo-French supersonic transport (TSS) criteria, with the limiting criterion being that takeoff safety speed be at least 1.15 times the one-engine-inoperative zero-rate-of-climb speed. Various observations related to SST certification are presented.

Snyder, C. T.↗

NASA NTRS1979

YF-17/ADEN system study

The YF-17 aircraft was evaluated as a candidate nonaxisymmetric nozzle flight demonstrator. Configuration design modifications, control system design, flight performance assessment, and program plan and cost we are summarized. Two aircraft configurations were studied. The first was modified as required to install only the augmented deflector exhaust nozzle (ADEN). The second one added a canard installation to take advantage of the full (up to 20 deg) nozzle vectoring capability. Results indicate that: (1) the program is feasible and can be accomplished at reasonable cost and low risk; (2) installation of ADEN increases the aircraft weight by 600 kg (1325 lb); (3) the control system can be modified to accomplish direct lift, pointing capability, variable static margin and deceleration modes of operation; (4) unvectored thrust-minus-drag is similar to the baseline YF-17; and (5) vectoring does not improve maneuvering performance. However, some potential benefits in direct lift, aircraft pointing, handling at low dynamic pressure and takeoff/landing ground roll are available. A 27 month program with 12 months of flight test is envisioned, with the cost estimated to be $15.9 million for the canard equipped aircraft and $13.2 million for the version without canard. The feasiblity of adding a thrust reverser to the YF-17/ADEN was investigated.

Gowadia, N. S.↗

NASA NTRS1984

Computer study of a jet flap ASTVOL 'Harrier'

A study of the costs/benefits trade-off was conducted for an Advanced Supersonic Short Takeoff and Vertical Landing (ASTOVL) aircraft incorporating a jet flap. The data used were the theory of jet flaps and high aspect ratio nozzles, experience with a V/STOL aircraft study performed for NASA Ames Research Center in February 1982, and a high performance aircraft-synthesis program (ACSYNT). The methodology was to accurately model the supersonic Harrier V/STOL aircraft design on ACSYNT, and then modify the design by both adding high aspect-ratio nozzles in place of the rear (core-flow) nozzles on the Pegasus-type turbofan engine, and integrating these nozzles on each wing's trailing edge, thus creating a jet flap. The predicted performance advantages (increase in maximum lift coefficient with flap deflection and horizontal thrust recovery) were traded off against the disadvantages (additional weight and thrust loss due to ducting) on two representative missions.

Wilson, S. B., III↗

NASA NTRS1999

An Experiment to Study Sporadic Atom Layers in the Earth's Mesosphere and Lower Thermosphere (SAL)

The Sudden Atom Layer (SAL) Rocket was successfully launched in February 1998. All instruments worked well except those supplied by NASA Goddard Space Flight Center. (A dummy weight was launched for the neutral mass spectrometer and the ion version died shortly after lift-off.) A paper has already been published in GRL concerning the dust layer detected by an on board instrument and compared to ground-based observations made at the Arecibo Observatory by Cornell graduate student S. Collins (lidar) and Q. Zhou (radar). Collins presented a comparison of the sodium lidar data and onboard observations with a theoretical model by Plane and Cox at the Fan AGU Meeting. In addition Gelinas and Kelley presented a review paper dealing with the entire SAL instrument complement at the same meeting. An unexpected new explanation for the outer scale of E region plasma irregularities has come out of the data set. We anticipate at least a total of four papers will be published within a year of launch.

Kelley, Michael C.↗

NASA NTRSDate not supplied

Examination of Unified Control Incorporating Generalized Control Allocation

Hybrid vehicles which combine vertical take off and landing with cruise configurations pose a unique challenge for control design and implementation. For this class of vehicle, successful control designs have historically broken the flight envelope into phases of flight and modified the control approach for each phase. This research approaches control in a unified way across the entire envelope utilizing a robust optimal design which provides effect or weighting then implemented in a generalized Affine Generalized Inverse control allocation algorithm. System performance for a Lift plus Cruise class vehicle is presented.

Unified Control,Control Allocation↗