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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 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
NASA NTRS1947

High-Speed Aerodynamic Characteristics of a 1/7-Scale Model of the Northrop YB-49 Airplane

Tests were conducted to find the effects of compressibility on the longitudinal stability and control of a 1/7-scale semispan model of the Northrop YB-49 airplane. Lift, drag, pitching moment, and elevon hinge moments were measured and are presented in graphical form. The results show that, due to a loss of lift on the outboard portion of the wing, the longitudinal static stability decreased rapidly as the Mach numbers increased above 0.735 the model experienced a climbing moment at positive lift coefficients. Also, a longitudinal-control effectiveness began to decrease at a Mach number of about 0.725

Robinson, Robert C.↗
NASA NTRS1991

Super/hypersonic aerodynamic characteristics for a transatmospheric vehicle concept having a minimum drag forebody

Experimental longitudinal and lateral-directional aerodynamic characteristics were obtained for a generic transatmospheric vehicle concept having a replaceable minimum drag forebody shape. The alternate forebody tested was a 1/4-power series body. Tests were made over a range of Mach numbers from 2 to 10 at a nominal Reynolds number, based on a length of 2.3 x 10 to the 8th and angles of attack from -4 to 20 deg. The minimum drag forebody provided significant improvements in minimum drag and L/D for the configuration as well as a longitudinally stabilizing increment. Although the baseline configuration is longitudinally unstable, the L/D improvements at low to moderate angles of attack would enhance cruise performance. Varying wing incidence angles was demonstrated as an effective horizontal trim device without significant trim drag penalties.

Phillips, W. P.↗
NASA NTRS1951

Investigation of the Low-Speed Stability and Control Characteristics of a 1/10-Scale Model of the Douglas XF4D-1 Airplane in the Langley Free-Flight Tunnel TED No. NACA DE 349

An investigation of the low-speed, power-off stability and control characteristics of a 1/10-scale model of the Douglas XF4D-1 airplane has been made in the Langley free-flight tunnel. The model was flown with leading-edge slats retracted and extended over a lift-coefficient range from 0.5 to the stall. Only relatively low-altitude conditions were simulated and no attempt was made to determine the effect on the stability characteristics of freeing the controls. The longitudinal stability and control characteristics of the model were satisfactory for all conditions investigated except near the stall with slats extended, where the model had a slight nosing-up tendency. The lateral stability and control characteristics of the model were considered satisfactory for all conditions investigated except near the stall with slats retracted, where a change in sign of the static- directional-stability parameter Cn(sub beta) caused the model to be directionally divergent. The addition of an extension to the top of the vertical tail did not increase Cn(sub beta) enough to eliminate the directional divergence of the model, but a large increase in Cn(sub beta) that was obtainable by artificial means appeared to eliminate the divergence and flights near the stall could be made. Artificially increasing the stability derivative-Cn(sub r) (yawing moment due to yawing) and Cn(sub p) (yawing moment due to rolling) had little effect on the divergence for the range of these parameters investigated. Calculations indicate that the damping of the lateral oscillation of the airplane with slats retracted or extended will be satisfactory at sea level but will be only marginally satisfactory at 40,000 feet.

Johnson, Joseph L.↗
NASA NTRS1932

Automatic Stability of Airplanes

It is endeavored in this report to give a full outline of the problem of airplane stability and to classify the proposed solutions systematically. Longitudinal stability, which can be studied separately, is considered first. The combination of lateral and directional stabilities, which cannot be separated, will be dealt with later.

Haus, FR↗
NASA NTRS1977

Utilization of separate surface control systems on general aviation aircraft

The application of separate surface control systems to general aviation aircraft is discussed. Block diagrams of a conventional control system with autopilot tie-in and of a separate surface control system are presented, and the advantages and disadvantages of the two systems are compared. Theoretical descriptions of pilot-in-the-loop operation and operation in the autopilot mode are presented. The application of separate surface stability augmentation in yaw dampers, wing levelers, and static longitudinal stability augmentation is examined. The state-of-the-art of separate control surface technology is summarized.

Roskam, J.↗
NASA NTRS1977

Effects of external stores on the air combat capability of a delta wing fighter

Delta wing point-design fighters with two pylon mounted missiles and aft tail controls (similar to several Soviet designs) have been investigated for a Mach number range from about 0.6 to 2.0. Whereas minimum drag penalties that are expected with the addition of external stores do occur, the effects at higher lifts, corresponding to maneuvering flight, are less severe and often favorable. The drag-due-to-lift factor is less with stores on although the lift curve slope is unaffected. The longitudinal stability level is reduced by the addition of stores while the pitch control effectiveness is unchanged. The directional stability was generally reduced at subsonic speeds and increased at supersonic speeds by the addition of stores but sufficiently high stability levels are obtainable that are compatible with the longitudinal maneuvering limits. Some examples of the potential maneuvering capability in terms of normal acceleration and turn radius are included.

Spearman, M. L.↗
NASA NTRS1933

Pressure Distribution Tests on a Series of Clark Y Biplane Cellules with Special Reference to Stability

The pressure distribution data discussed in this report represents the results of part of an investigation conducted on the factors affecting the aerodynamic safety of airplanes. The present tests were made on semispan, circular-tipped Clark Y airfoil models mounted in the conventional manner on a separation plane. Pressure readings were made simultaneously at all test orifices at each of 20 angles of attack between -8 degrees and +90 degrees. The results of the tests on each wing arrangement are compared on the bases of maximum normal force coefficient, lateral stability at a low rate of roll, and relative longitudinal stability. Tabular data are also presented giving the center of pressure location of each wing.

Noyes, Richard W↗
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↗
NASA NTRS1921

A Mechanical Device for Illustrating Airplane Stability

An instrument is described which will illustrate completely in a qualitative sense the longitudinal stability characteristics of an airplane. The instrument is primarily of use for the lecture room, but it is hoped that ultimately it will be possible to obtain quantitative results from it.

Norton, F H↗
NASA NTRS1978

An aerodynamic analysis of several hypersonic research airplane concepts from M = 0.2 to 6.0

Several conceptual hypersonic research airplanes, designed within the constraints of a B-52 launch aircraft, have been studied experimentally and analytically at Mach numbers from 0.2 to 6.0. Vehicles built to these criteria for Mach 6 cruise were shown to be feasible, if careful attention was paid to the low speed lift, drag, and high angle of attack stability to assure successful landings and transonic pitch angle maneuvers. The integrated scramjet engine drag was high at subsonic speeds and appears to be constant with Reynolds number. The variable geometry airfoil used previously to improve directional stability was shown to be equally adaptable to the improvement of longitudinal stability. The vortex lattice theory gave good subsonic predictions of lift, drag due to lift, and pitching moments. Wind tunnel tests must be relied on for the drag at zero lift, trim, static margins and lateral-directional stability. The Gentry Hypersonic Arbitrary Body Program gave good predictions of the trends of lift, drag, and pitching moments with angle of attack at Mach numbers above 3, but the level of the values were not consistently predicted. No currently available theory or program gave accurate predictions of directional stability or dihedral effects at hypersonic speeds.

Penland, J. A.↗
DOE OSTI2024

LINAC Longitudinal Simulation and Measurement of Output Energy

The Linac at Fermilab, one of the oldest accelerators on-site, plays a crucial role in delivering 400 MeV proton beams to other accelerating facilities. The beam traveling through Linac needs to be carefully monitored for better accelerator operation. One of the key factors of efficient Linac operation is its longitudinal stability. The stability can minimize Linac loss and maximize beam current. For this purpose, I examined the beam's longitudinal profile, which is crucial for proper beam transfer between its two sections. After careful monitoring of the beam through Linac, we need to ensure that it leaves with desired parameters. The beam coming out from the Linac is subsequently injected into the Booster, a synchrotron that relies on dipole magnets to bend the beam at injection. If the output energy of the beam deviates from the expected value, the beam will bend at an incorrect radius, leading to potential beam loss. Therefore, precise regulation of the output energy is critical for the efficient operation of the accelerator. To address this, I have conducted a thorough examination of the Linac longitudinal simulations and data from Beam Position Monitors (BPMs). My objective is to measure and stabilize the output energy and verify its correspondence with the predicted simulation results. All these analyses are important for efficient operation of the accelerator.

Safaryan, Milena↗
NASA NTRS1979

Stability and control characteristics of a monoplanar elliptic missile model at Mach numbers from 1.60 to 2.86

An investigation was conducted of a monoplanar maneuverable missile concept having a nose forebody with a circular cross section and a centerbody and afterbody with elliptical cross sections. The tests involved several component changes and were conducted in the low Mach number test section of the Langley Unitary Plan wind tunnel at Mach numbers of 1.60, 2.16, and 2.86, at angles of attack ranging from -4 degs to 28 degs and at sideslip angles ranging from -4 degs to 8 degs. The most significant result was that at the highest Mach number (2.86), the configuration with the infrared nose produced nearly twice the axial force as the same configuration with the radar nose. The cranked wing had a destabilizing effect on the longitudinal stability and had no effect on the lateral-directional stability. The nose strakes had no effect longitudinally and were detrimental to the lateral-directional stability.

Sawyer, W. C.↗