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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1961

Static Stability and Control of Canard Configurations at Mach Numbers from 0.70 to 2.22 - Triangular Wing and Canard with Twin Vertical Tails

The static aerodynamic characteristics of a canard airplane configuration having twin vertical stabilizing surfaces are presented. The model consisted of a wing and canard both of triangular plan form and aspect ratio 2 mounted on a Sears-Haack body of fineness ratio 12.5 and two swept and tapered wing-mounted vertical tails of aspect ratio 1.35. Data are presented for Mach numbers from 0.70 to 2.22 and for angles of attack from -6 to +18 deg. at 0 and 5 deg. sideslip. Tests were made with the canard off and with the canard on. Nominal canard deflection angles ranged from 0 to 10 deg. The Reynolds number was 3.68 x 10(exp 6) based on the wing mean aerodynamic chord. Selected portions of the data obtained in this investigation are compared with previously published results for the same model having a single vertical tail instead of twin vertical tails. Without the canard, the directional stability at supersonic Mach numbers and high angles of attack was improved slightly by replacing the single tail with twin tails. However, at a Mach number of 0.70, the directional stability of the twin-tail model deteriorated rapidly with increasing angle of attack above 10 deg. and fell considerably below the level for the single-tail model. At subsonic speeds the directional stability of the twin-tail model with the canard was comparable to that for the single-tail model and at supersonic speed it was considerably greater at high angles of attack. Unlike the single-tail model, the twin-tail model at 50 sideslip exhibited an unstable break in the variation of pitching-moment coefficient with lift coefficient near 10 deg. angle of attack for 0.70 Mach number.

Peterson, Victor L.↗
NASA NTRS1994

Convection and morphological stability during directional solidification

For growth of a vicinal face at constant velocity, the effect of anisotropic interface kinetics on morphological stability is calculated for a binary alloy. The dependence of the interface kinetic coefficient on crystallographic orientation is based on the motion and density of steps. Anisotropic kinetics give rise to traveling waves along the crystal-melt interface, and can lead to a significant enhancement of morphological stability. The stability enhancement increases as the orientation approaches a singular orientation and as the solidification velocity increases. Shear flows interact with the traveling waves and, depending on the direction of the flow, may either stabilize or destabilize the interface. Specific calculations are carried out for germanium-silicon alloys.

Coriell, Sam R.↗
NASA NTRS1972

Effects of an in-flight thrust reverser on the stability and control characteristics of a single-engine fighter airplane model

The changes in thrust minus drag performance as well as longitudinal and directional stability and control characteristics of a single-engine jet aircraft attributable to an in-flight thrust reverser of the blocker-deflector door type were investigated in a 16-foot transonic wind tunnel. The longitudinal and directional stability data are presented. Test conditions simulated landing approach conditions as well as high speed maneuvering such as may be required for combat or steep descent from high altitude.

Mercer, C. E.↗
NASA NTRS1968

Aerodynamic Characteristics of Several Hypersonic Boost-Glide-Type Configurations at Mach Numbers from 2.30 to 4.63

An investigation has been conducted at Mach numbers from 2.30 to 4.63 to determine the static aerodynamic characteristics of several configurations designed for flight at hypersonic Mach numbers. Two all-wing and three wing-body configurations were tested through an angle-of-attack range from about -4 degrees to 33 degrees and an angle-of-sideslip range from about -4 degrees to 8 degrees at a Reynolds number of 3 times 10 (sup 6) per foot (9.84 times 10 (sup 6) per meter). The results of the investigation indicated that the wing-body configurations produced higher values of maximum lift-drag ratio than those produced by the all-wing models. The high wing-body configurations tend to have a self-trimming capability as opposed to that for the low wing-body configurations. Each of the configurations produced a positive dihedral effect that increased with increasing angle of attack and decreased with increasing Mach number. The high wing-body models produced decreasing values of directional stability with increase in angle of attack, whereas the low wing-body models provided increasing values of directional stability with increase in angle of attack.

Graves, Ernald B.↗
NASA NTRS1958

Wind-Tunnel Investigation of the Low-Speed Characteristics of a 1/8-Scale Model of the Republic XP-91 Airplane with a Vee and a Conventional Tail. Addendum - Characteristics with a Revised Conventional Tail and Drooped Wing Tips

Additional wind-tunnel tests were made of a 1/8-scale model of the Republic XP-91 airplane to determine its characteristics with various modifications. The modifications included a revised conventional tail, revised rocket arrangement, drooped wing tips, and revised landing gear and doors. Tests were also made to determine the effectiveness of the control surfaces of the model with the conventional tail and the effect of changing wing incidence and tail length. The revised rocket arrangement provided a considerable increase in the static directional stability contributed by the vee tail at small angles of yaw. The conventional tail provided a greater static directional stability than the vee tail without increasing the rolling moment due to sideslip. The rolling moment die to sideslip was considerable reduced by either drooped wing tips or open main landing-gear doors. The reduction in rolling moment due to sideslip resulting from the drooped tips was less with the landing-gear doors open than with the doors closed. A change in wing incidence from 0 degrees to 6 degrees reduced the elevator angle required for balance by approximately 6 degrees.

Weiberg, James A.↗
NASA NTRS1977

Aerodynamic characteristics of a 1/6-scale powered model of the rotor systems research aircraft

A wind-tunnel investigation was conducted to determine the effects of the main-rotor wake on the aerodynamic characteristics of the rotor systems research aircraft (RSRA). For the investigation, a 1/6-scale model with a four-blade articulated main rotor was used. Tests were conducted with and without the main rotor. Both the helicopter and the compound helicopter were tested. The latter configuration included the auxiliary thrust engines and the variable-incidence wing. Data were obtained over ranges of angle of attack, angle of sideslip, and main-rotor collective pitch angle at several main-rotor advance ratios. Results are presented for the total loads on the airframe as well as the loads on the rotor, the wing, and the tail. The results indicated that without the effect of the rotor wake, the RSRA had static longitudinal and directional stability and positive effective dihedral. With the effect of the main rotor and its wake, the RSRA exhibited longitudinal instability but retained static directional stability and positive effective dihedral.

Mineck, R. E.↗
NASA NTRS1999

Preliminary Results of the 1.5% TCA (Modular) Controls Model in the NASA Langley UPWT

To summarize the significant highlights in this report: (1) Data quality, determined by multiple repeat runs performed on the TCA baseline configuration, and long-term repeatability, determined by comparing baseline Reference H data from this test to a previous test, have been shown to be good. (2) The longitudinal stability of the TCA is more non-linear than for the Reference H, and while it is similar at normal lift values, the TCA has considerably more pitch-up at higher lift. (3) Longitudinal control effectiveness of the TCA is similar to the Reference H and the ratio of elevator effectiveness to horizontal tail effectiveness is approximately 0.3. (4) The directional stability of the TCA is improved relative to Reference H at higher angles-of attack. The chine is effective for improving directional stability.

Kubiatko, Paul↗
NASA NTRS1958

Investigation of Control Effectiveness and Stability Characteristics of a Model of a Low-Wing Missile with Interdigitated Tail Surfaces at Mach Numbers of 2.29, 2.97, and 3.51

A brief investigation of the longitudinal stability and control effectiveness at supersonic speeds of a model of a low-wing missile with interdigitated tail surfaces was made in the Langley Unitary Plan wind tunnel. The data were obtained at Mach numbers M of 2.29, 2.97, and 3.51 for Reynolds number (based on the mean geometric chord of the wing) of 1.15 x 10(exp 6), 1.14 x 10(exp 6), and 1.11 x 10(exp 6), respectively. Data were obtained for three settings of the longitudinal control surfaces: with deflection of all surfaces, with deflection of the lower surfaces only, and with all surfaces undeflected. Directional stability data were obtained at M=3.51 for angles of attack of approximately 0 deg and 10 deg. These data, with summary data and typical schlieren photographs, are presented with only a brief analysis. The data indicate that the controls are effective throughout the Mach number range and lift-coefficient range (CL = -0.15 to 0.7, approximately) of the tests. There is a severe break in the pitching-moment curve at M=2.29 which might result in a pitch-up condition in flight, and also a large forward movement of the aerodynamic center with increasing Mach number that produces neutral longitudinal stability at M=3.51 for the moment center used in this investigation. The model was directionally unstable at M=3.51; however, the level of directional stability was about the same for 0 deg and 10 deg angles of attack.

STABILITY AND CONTROL↗
DOE OSTI2025

Propylamine Functionalized Porous Fiber Sorbents with High Oxidation Stability for Direct Air Capture

Amine-based sorbents are highly effective for direct air capture (DAC) due to their excellent CO2 capture efficiency under ultra-dilute conditions. However, these sorbents can suffer degradation when exposed to combinations of heat, oxygen, and other atmospheric components, indicating a need for improved sorbent stability. In this study, we developed amidoxime functionalized polymer of intrinsic microporosity (PIM-1-AO) fibers with tethered amines, specifically tris(2-aminoethyl)amine (TAEA) and tris(3-aminopropyl)amine (TAPA), denoted as PIM-1-AO-TAEA and PIM-1-AO-TAPA, respectively. In addition, large scale sorbent fiber spinning has been successfully performed by producing meters of fibers in the lab. We demonstrated that substituting TAEA with TAPA, which has propyl chains instead of ethyl chains, reduces oxidative degradation under regeneration conditions. The findings revealed that PIM-1-AO-TAPA not only significantly outperforms PIM-1-AO-TAEA after accelerated aging process, but also outperforms any other sorbent used in DAC aged under similar conditions. Moreover, PIM-1-AO-TAPA sorbent fibers showed one of the highest amine efficiencies (0.25) considering the low amine loading (21%) coupled with robust CO2 uptake performance (1.12 mmol/g) under DAC conditions.

amine-based sorbent↗
NASA NTRS1954

Measurement of the Static Stability and Control and the Damping Derivatives of a 0.13-Scale Model of the Convair XFY-1 Airplane, TED No. NACA DE 368

An investigation has been conducted to determine the static stability and control and damping in roll and yaw of a 0.13-scale model of the Convair XFY-1 airplane with propellers off from 0 deg to 90 deg angle of attack. The tests showed that a slightly unstable pitch-up tendency occurred simultaneously with a break in the normal-force curve in the angle-of-attack range from about 27 deg to 36 deg. The top vertical tail contributed positive values of static directional stability and effective dihedral up to an angle of attack of about 35 deg. The bottom tail contributed positive values of static directional stability but negative values of effective dihedral throughout the angle-of-attack range. Effectiveness of the control surfaces decreased to very low values at the high angles of attack, The model had positive damping in yaw and damping in roll about the body axes over the angle-of-attack range but the damping in yaw decreased to about zero at 90 deg angle of attack.

Johnson, Joseph L.↗
NASA NTRS1979

Effects of a military cargo pod and tail fins on the aerodynamic characteristics of a large wide-body transport model

Wind tunnel tests were conducted on a 0.03 scale model of a large wide-body commercial aircraft to determine the effects on the static aerodynamic characteristics resulting from the attachment of a belly pod for the long-range deployment of outsize military equipment. The effectiveness of horizontal-tip fins in augmenting directional stability was investigated. At a test Reynolds number of 1.08 x 1,000,000, the addition of the pod results in an increase in total drag of approximately 20 percent. Trim drag due to the pod is very small. Although the pod produces a significant decrease in directional stability, the addition of the tip fins restores some of the stability, particularly at the lower angles of attack.

Jernell, L. S.↗
NASA NTRS1992

Backward assembly planning with DFA analysis

An assembly planning system that operates based on a recursive decomposition of assembly into subassemblies is presented. The planning system analyzes assembly cost in terms of stability, directionality, and manipulability to guide the generation of preferred assembly plans. The planning in this system incorporates the special processes, such as cleaning, testing, labeling, etc., that must occur during the assembly. Additionally, the planning handles nonreversible, as well as reversible, assembly tasks through backward assembly planning. In order to decrease the planning efficiency, the system avoids the analysis of decompositions that do not correspond to feasible assembly tasks. This is achieved by grouping and merging those parts that can not be decomposable at the current stage of backward assembly planning due to the requirement of special processes and the constraint of interconnection feasibility. The invention includes methods of evaluating assembly cost in terms of the number of fixtures (or holding devices) and reorientations required for assembly, through the analysis of stability, directionality, and manipulability. All these factors are used in defining cost and heuristic functions for an AO* search for an optimal plan.

Lee, Sukhan↗
NASA NTRS1995

Backward assembly planning with DFA analysis

An assembly planning system that operates based on a recursive decomposition of assembly into subassemblies, and analyzes assembly cost in terms of stability, directionality, and manipulability to guide the generation of preferred assembly plans is presented. The planning in this system incorporates the special processes, such as cleaning, testing, labeling, etc. that must occur during the assembly, and handles nonreversible as well as reversible assembly tasks through backward assembly planning. In order to increase the planning efficiency, the system avoids the analysis of decompositions that do not correspond to feasible assembly tasks. This is achieved by grouping and merging those parts that can not be decomposable at the current stage of backward assembly planning due to the requirement of special processes and the constraint of interconnection feasibility. The invention includes methods of evaluating assembly cost in terms of the number of fixtures (or holding devices) and reorientations required for assembly, through the analysis of stability, directionality, and manipulability. All these factors are used in defining cost and heuristic functions for an AO* search for an optimal plan.

Lee, Sukhan↗
NASA NTRS1973

C-5A/orbiter wind tunnel testing and analysis: Piggyback ferry

Wind tunnel testing and analytical studies of the feasibility of ferrying the NASA Shuttle Orbiter on the C-5A in a piggyback mode have been accomplished. Testing was conducted in the 8x12 foot low speed wind tunnel using an existing 0.0399 scale C-5A model in conjunction with a NASA 0.0405 scale Orbiter model. Six component force and moment data were measured over a range of pitch and yaw angles to determine lift and drag characteristics, lateral/directional stability characteristics and longitudinal and directional control powers. A description of the wind tunnel test program with a run schedule and the complete plotted data for all the test runs are presented. Initial emphasis was given to determining the effects of the Orbiter above the C-5A and the optimum location for minimum interference on C-5A characteristics. A comprehensive series of cruise configurations were tested including a range of Orbiter longitudinal and vertical locations, incidences, and afterbody fairings. Subsequently, a series of configurations were devised during the test program to determine means of recovering directional stability degradation due to Orbiter interference.

Tomlin, K. H.↗
NASA NTRS1983

Some lessons from NACA/NASA aerodynamic studies following World War II

An historical account is presented of the new departures in aerodynamic research conducted by NACA, and subsequently NASA, as a result of novel aircraft technologies and operational regimes encountered in the course of the Second World War. The invention and initial development of the turbojet engine furnished the basis for a new speed/altitude regime in which numerous aerodynamic design problems arose. These included compressibility effects near the speed of sound, with attendant lift/drag efficiency reductions and longitudinal stability enhancements that were accompanied by a directional stability reduction. Major research initiatives were mounted in the investigation of swept, delta, trapezoidal and variable sweep wing configurations, sometimes conducted through flight testing of the 'X-series' aircraft. Attention is also given to the development of the first generation of supersonic fighter aircraft.

Spearman, M. L.↗
NASA NTRS1986

Subsonic aerodynamic characteristics of a circular body earth-to-orbit transport

To reduce the weight and improve the performance of future earth-to-orbit transports, the use of circular cross sections in the fuselage bodies of these vehicles is being considered at the Langley Research Center. Structurally, circular cross sections are stronger and lighter than other shapes. A study has been made applying the circular body concept to a vertical-takeoff, delta-winged, single-stage-to-orbit transport. A 52 in., 0.022-scale model of the circular body vehicle was tested at a Mach number of 0.3 in the 7 x 10 ft High Speed Wind Tunnel at the Langley Research Center to obtain aerodynamic forces and moments. Oil-flow photographs were taken at several angles of attack to aid in the aerodynamic analysis. Model control surfaces included elevons and ailerons for the evaluation of pitch and roll characteristics and either wing-tip fins, a nose mounted dorsal fin, or a conventional vertical tail for the evaluation of yaw characteristics. Other deflecting surfaces included speedbrakes and body flaps. Basic data on longitudinal flight characteristics are shown, including lift, drag, and pitching moments. Comparisons of the directional stability and control effectiveness of the three directional control devices are also shown.

Lepsch, R. A., Jr.↗
NASA NTRS1945

An Experimental Investigation of the Effect of Propellers Used as Aerodynamic Brakes on Stability and Control

Tests were made of a model representative of a single-engine tractor-type airplane for the purpose of determining the stability and control effects of a propeller used as an aerodynamic brake. The tests were made with single-and dual-rotation propellers to show the effect of type of propeller rotation, and with positive thrust to provide basic data with which to compare the effects of negative thrust. Four configurations of the model were used to give the effects of tilting the propeller thrust axis down 5 deg., raising the horizontal tail, and combining both tilt and raised tail. Results of the tests are reported herein. The effects of negative thrust were found to be significant. The longitudinal stability was increased because of the loss of wing lift and increase of the angle of attack of the tail. Directional stability and both longitudinal and directional control were decreased because of the reduced velocity at the tail. These effects are moderate for moderate braking but become pronounced with full-power braking, particularly at high values of lift coefficient. The effects of model configuration changes were small when compared with the over-all effects of negative-thrust operation; however, improved stability and control characteristics were exhibited by the model with the tilted thrust axis. Raising the horizontal tail improved the longitudinal characteristics, but was detrimental to directional characteristics. The use of dual-rotation propeller reduced the directional trim charges resulting from the braking operation. A prototype airplane was assumed and handling qualities were computed and analyzed for normal (positive thrust) and braking operation with full and partial power. The results of these analyses are presented for the longitudinal characteristics in steady and accelerated flight, and for the directional characteristics in high- and low-speed flight. It was found that by limiting the power output of the engine (assuming the constant-speed propeller will function in the range of blade angles required for negative thrust) the stability and control characteristics may be held within the limits required for safe operation. Braking with full power, particularly at low speeds, is dangerous, but braking with very small power output is satisfactory from the standpoint of control. The amount of braking produced with zero power output is equal to or better than that produced by conventional spoiler-type brakes.

AIRPLANES, MILITARY↗