Search NASA⌕ Search

Engineering topics

Nelms, W. P.

Publications and source records attributed to Nelms, W. P..

14 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Assessment of aerodynamic performance of V/STOL and STOVL fighter aircraft

The aerodynamic performance of V/STOL and STOVL fighter/attack aircraft was assessed. Aerodynamic and propulsion/airframe integration activities are described and small and large scale research programs are considered. Uncertainties affecting aerodynamic performance that are associated with special configuration features resulting from the V/STOL requirement are addressed. Example uncertainties relate to minimum drag, wave drag, high angle of attack characteristics, and power induced effects.

Nelms, W. P.↗
NASA NTRS1981

Airframe effects on top-mounted inlet systems for VSTOL fighter aircraft

Inlet flow-field and compressor-face performance data were obtained for a 0.095-scale model of a VSTOL fighter-attack aircraft configuration with twin top-mounted inlets. Tests were conducted at Mach numbers from 0.6 to 2.0 and at angles of attack and sideslip up to 27 deg and 12 deg, respectively. The effects of inlet location, wing leading-edge extension planform area, canopy-dorsal integration, and variable incidence canards were determined. The results show that distortion at the compressor face when maneuvering is relatively low (20% or less) at Mach numbers up to 0.9. However, at Mach numbers of 1.2 and above, maneuverability may be restricted because of high distortion or low pressure recovery (80% or less) or both.

Smeltzer, D. B.↗
NASA NTRS1981

Concept definition and aerodynamic technology studies for single-engine V/STOL fighter/attack aircraft

The results obtained in the early stages of a research program to develop aerodynamic technology for single-engine V/STOL fighter/attack aircraft projected for the post-1990 period are summarized. This program includes industry studies jointly sponsored by NASA and the Navy. Four contractors have identified promising concepts featuring a variety of approaches for providing propulsive lift. Vertical takeoff gross weights range from about 10,000 to 13,600 kg (22,000 to 30,000 lb). The aircraft have supersonic capability, are highly maneuverable, and have significant short takeoff overload capability. The contractors have estimated the aerodynamics and identified aerodynamic uncertainties associated with their concepts. Wind-tunnel research programs will be formulated to investigate these uncertainties. A description of the concepts is emphasized.

Nelms, W. P.↗
NASA NTRS1981

Top-mounted inlet system feasibility for transonic-subsonic fighter aircraft applications

To inlet flow field and engine inlet performance data for an advanced fighter aircraft configuration were obtained over the Mach 0.6 to 2.0 range. The studies not only provided extensive data for the baseline arrangement, but also evaluated the effects of key aircraft configuration variables (inlet location, canopy-dorsal integration, wing leading-edge extension planform area, and variable incidence canards) on top inlet performance. In order to set these data in the context of practical aircraft systems top inlet performance is compared with that of more conventional inlet/airframe integrations. The results of these evaluations show that, for the top inlet configuration tested, relatively good inlet performance and compatibility characteristics are maintained during subsonic and transonic maneuver. However, at supersonic speeds, flow expansion over the forebody and wings causes an increase in local inlet Mach number subsequently reduces inlet performance levels. These characteristics infer that although top inlets many not pose a viable design option for aircraft requiring a high degree of supersonic maneuverability, they have distinct promise for vehicles with subsonic and transonic maneuver capabilities.

Williams, T. L.↗
NASA NTRS1981

Experimental aerodynamic characteristics of two V/STOL fighter/attack aircraft configurations at Mach numbers from 1.6 to 2.0

Tests were conducted in the Ames 9 by 7 ft supersonic wind tunnel to measure the aerodynamic characteristics of two horizontal attitude takeoff and landing V/STOL fighter/attack aircraft concepts. One concept featured a jet diffuser ejector for its vertical lift system and the other employed a remote augmentation lift system (RALS). Test results for Mach numbers from 1.6 to 2.0 are reported. Effects of varying the angle of attack (-4 deg to +17 deg), angle of sideslip (-4 deg to +8 deg) Mach number, and configuration building were investigated. The effects of wing trailing edge flap deflections, canard incidence, and vertical tail deflections were also explored as well as the effects of varying the canard longitudinal location and shapes of the inboard nacelle body strakes.

Nelms, W. P.↗
NASA NTRS1981

Top-mounted inlet system feasibility for transonic-supersonic fighter aircraft

The more salient findings are presented of recent top inlet performance evaluations aimed at assessing the feasibility of top-mounted inlet systems for transonic-supersonic fighter aircraft applications. Top inlet flow field and engine-inlet performance test data show the influence of key aircraft configuration variables-inlet longitudinal position, wing leading-edge extension planform area, canopy-dorsal integration, and variable incidence canards-on top inlet performance over the Mach range of 0.6 to 2.0. Top inlet performance data are compared with those or more conventional inlet/airframe integrations in an effort to assess the viability of top-mounted inlet systems relative to conventional inlet installations.

Williams, T. L.↗
NASA NTRS1980

Experimental aerodynamic characteristics of two V/STOL fighter/attack aircraft configurations at Mach numbers from 0.4 to 1.4

A wind tunnel test was conducted to measure the aerodynamic characteristics of two horizontal attitude takeoff and landing V/STOL fighter/attack aircraft concepts. In one concept, a jet diffuser ejector was used for the vertical lift system; the other used a remote augmentation lift system (RALS). Wind tunnel tests to investigate the aerodynamic uncertainties and to establish a data base for these types of concepts were conducted over a Mach number range from 0.2 to 2.0. The present report covers tests, conducted in the 11 foot transonic wind tunnel, for Mach numbers from 0.4 to 1.4. Detailed effects of varying the angle of attack (up to 27 deg), angle of sideslip (-4 deg to +8 deg), Mach number, Reynolds number, and configuration buildup were investigated. In addition, the effects of wing trailing edge flap deflections, canard incidence, and vertical tail deflections were explored. Variable canard longitudinal location and different shapes of the inboard nacelle body strakes were also investigated.

Nelms, W. P.↗
NASA NTRS1980

Preliminary aerodynamic characteristics of several advanced VSTOL fighter/attack aircraft concepts

VSTOL attack aircraft to be developed in the mid- or late-1990's and research programs dealing with possible characteristics are discussed. Design studies of horizontal attitude takeoff and landing (HATOL) and vertical attitude takeoff and landing (VATOL) type aircraft were executed and wind tunnel models were built and tested. The configurations tested were a wing-canard HATOL concept with jet-diffuser ejectors as a vertical lift system and a variety of the same with nacelles which are closer together. Other proposals were a HATOL concept with wing-canard design and two vertical tails on twin afterbodies, and a VATOL concept which is tailless with an extended leading-edge wing to increase lift. Aerodynamic uncertainties were defined and wind tunnel tests were made. Special research concerning top-mounted air induction systems is also covered.

Nelms, W. P.↗
NASA NTRS1978

Studies of aerodynamic technology for VSTOL fighter/attack aircraft

The paper summarizes several studies to develop aerodynamic technology for high performance VSTOL aircraft anticipated after 1990. A contracted study jointly sponsored by NASA-Ames and David Taylor Naval Ship Research and Development Center is emphasized. Four contractors analyzed two vertical-attitude and three horizontal-attitude takeoff and landing concepts with gross weights ranging from about 10433 kg (23,000 lb) to 17236 kg (38,000 lb). The aircraft have supersonic capability, high maneuver performance (sustained load factor 6.2 at Mach 0.6, 3048 m (10,000 ft)) and a 4536 kg (10,000-lb) STO overload capability. The contractors have estimated the aerodynamics and identified aerodynamic uncertainties associated with their concept. Example uncertainties relate to propulsion-induced flows, canard-wing interactions, and top inlets. Wind-tunnel research programs were proposed to investigate these uncertainties.

Nelms, W. P.↗
NASA NTRS1977

Remotely piloted aircraft in the civil environment

Remotely piloted aircraft (RPA's) are of increasing interest to the military and others, as evidenced by a number of technology and development programs that are currently funded or planned. These programs have led to a number of test aircraft with significant capabilities, and future remotely piloted aircraft are forecast to become even more capable as the technology in a number of important subsystem areas is progressing at a rapid rate. As the size, weight and cost of RPA's is reduced, the prospect of using them for civilian applications becomes more likely.

Gregory, T. J.↗
NASA NTRS1977

Remotely piloted aircraft in the civil environment

Improved remotely piloted aircraft (RPAs), i.e., incorporating reductions in size, weight, and cost, are becoming available for civilian applications. Existing RPA programs are described and predicted into the future. Attention is given to the NASA Mini-Sniffer, which will fly to altitudes of more than 20,000 m, sample the atmosphere behind supersonic cruise aircraft, and telemeter the data to ground stations. Design and operating parameters of the aircraft are given, especially the optical sensing systems, and civilian RPA uses are outlined, including airborne research, remote mapping, rescue, message relay, and transportation of need materials. Civil regulatory factors are also dealt with.

Gregory, T. J.↗
NASA NTRS1974

RPVs - Exploring civilian applications

Discussion of the civilian application possibilities for remotely piloted vehicle (RPV) systems. Following a listing of all possible desert, coastal, forest, agricultural, and urban RPV missions, a thorough examination is presented of such possible RPV aircraft applications as those of forest-fire detection and mapping. Some of the major obstacles to such civilian missions are also reviewed.

Gregory, T. J.↗