Aerodynamic Flight Research Articles

Generalized similarity laws for flows around bodies in conditions of “localizability” law: PMM vol. 37, n≗5, 1973, pp. 857–863

It is shown that generalized similarity laws which interrelate the aerodynamic characteristics (lift and drag coefficients) of a body can be established for the general case of nonaffine-similar bodies to which conditions of the localizability law apply, i.e. when the momentum stream, at the body surface depends on local properties of the latter (Newtonian hypersonic gas flow, ratified gas flow, effect of light, etc.). Methods are derived for the construction of complementary bodies and examples of application of the proposed similarity laws are given. These laws are well known and widely applied in practical problems of flow of perfect gas around bodies at various velocities. They make it possible to determine from known aerodynamic characteristics of a given body its characteristics at various Mach numbers and, in some cases, to determine the lift and drag coefficients of affine-similar bodies [1, 2]. Various theories, in the main based on assumptions that the momentum stream at the body surface primarily depends on the local properties of the latter and on the local angle between the normal to the surface and the direction of flight velocity (the so-called “localizability” law), are successfully used in many areas of flight aerodynamics and dynamics. Specific universal relationships between aerodynamic forces and moments are inherent to flows in conditions of the localizability law [3]. It is shown that conditions of the localizability law make it possible to establish generalized similarity laws which interrelate aerodynamic characteristics of bodies, including nonaffine-similar bodies. A particular case of these laws for Newtonian hypersonic gas flow was considered in [4] on a number of additional assumptions.

Control-power usage for maneuvering in hover of the VJ 101 aircraft.

For a number of flight maneuvers that are typical for hover operation, flight-test data of the VJ 101 C XI/X2 aircraft and of a hover-rig were analyzed. All three vehicles were similar in thrust geometry and mass distribution but partly different in effective aerodynamic shape. They all used the same principles of control and type of control system for hovering operations. The hover-rig was flown both in rate and attitude modes of control, whereas the airplanes were flown in attitude-mode control only. On the VJ 101 X2, thrust modulation of afterburning engines was used for control. The flight tests were conducted under visual flight rules (VFR) conditions, with wind less than 15 knots. The results show that the mean values of control-power usage for the different maneuvers analyzed are in their relation basically similar for hover-rig and airplanes. In most of the cases vertical takeoff or vertical landing require the highest value of control power. A comparison of angular acceleration usage and pilot control action for an attitude-dema nd and rate-demand type of control shows a slight advantage for attitude-demand control. The influence of vehicle weight on maximum control power used seems to follow different trends for the pitch axis and roll-yaw axes, respectively. The pitch-axis results do not show an influence of weight; whereas in roll and yaw, the maximum control power used decreases with weight. The frequency contents of pilot inputs do not seem to differ from aerodynamic flight and there is no obvious influence of mode of control. Correlation of pilot's inputs as well as autopilot's inputs in pitch and roll is rather low. Finally, the handling-qualities recommendatio ns for hover control are reviewed in the light of these results.

1173. An electrically-operated two-way gas valve

New developments in materials science in the areas of solution gelation processes and nanotechnology have led to the recent commercial production of aerogels. Concurrent with these advancements has been the development of new approaches to cryogenic thermal insulation systems. For example, thermal and physical characterizations of aerogel beads under cryogenic-vacuum conditions have been performed at the Cryogenics Test Laboratory of the NASA Kennedy Space Center. Aerogel-based insulation system demonstrations have also been conducted to improve performance for space launch applications. Subscale cryopumping experiments show the thermal insulating ability of these fully breathable nanoporous materials. For a properly executed thermal insulation system, these breathable aerogel systems are shown to not cryopump beyond the initial cooldown and thermal stabilization phase. New applications are being developed to augment the thermal protection systems of space launch vehicles, including the Space Shuttle External Tank. These applications include a cold-boundary temperature of 90 K with an ambient air environment in which both weather and flight aerodynamics are important considerations. Another application is a nitrogen-purged environment with a cold-boundary temperature of 20 K where both initial cooldown and launch ascent profiles must be considered. Experimental results and considerations for these flight system applications are discussed.

Aerodynamics of Hypersonic Flight

Elements of Hypersonic Aerodynamics By Dr. R. N. Cox and Dr. L. F. Crabtree. (Applied Physics Guides.) Pp. xii + 243. (London: The English Universities Press, Ltd., 1965.) 35s. net.

On the quality of man parameters

The quality of man parameters was found to be of not equivalent standard to the quality of machine and environment parameters, ergo providing both a challenge to improve that quality and a requirement to re-examine tenets for measuring and expressing man parameters. Here the authors concentrate on another of the eleven subsystems which constitute the total integrated human physiological system. Results for the respiratory-metabolic subsystems here presented agree in essence with results for the cardiovascular subsystem currently studied. That is, characteristic statistics for selected rate and acceleration formulae (which had been formulated to preserve the characteristic instantaneity of a regulating human subsystem) demonstrate that one rate formulae and one acceleration formula best descrobe and typify instantaneous physiological function of healthy man who performs under the rigors of omni-sonic aerodynamic flight.

Contributions of the x-15 program to lifting entry technology

Entries from altitudes greater than 350,000 ft with the X-15 airplane have provided piloting experience and verification of predicted control characteristics and operational techniques. The airplane re-enters as a glider and duplicates several phases in the recovery of higher-performance vehicles, for example, transition from near-zero dynamic pressure to aerodynamic flight, and the terminal-area ranging and landing. During entries, reaction controls have been used to surprisingly high dynamic pressures. Rate command control provided satisfactory control, and hold modes were appreciated by the pilots for secondary control mocjes. With conservatively planned flights, the pilots have had no problem controlling range to base with contact navigation. Landmarks have been observed from above 300,000 ft and 160 miles range. The approach and landing of the low-lift-drag-ratio X-15 airplane has become routine, with relatively small dispersion in touchdown and slideout distance. The speed brakes have been an important control for regulation of ranging for landing; however, the pilots indicated that faster-acting speed brakes would allow more flexible operation. D 9 = L := q = Nomenelatu re drag acceleration due to gravity, ft/sec2 lift dynamic pressure, psf angle of attack, deg pitch angle, deg roll angle, deg yaw angle, deg

Physical Chemistry in Aerodynamics and Space Flight

Abstract : Contents: Surface and solid phase reactions; Gas phase reactions and kinetics; Experimental methods and simulation; Thermodynamic and transport properties of gases.

Flow Over a Cone at an Angle of Attack for High Mach Number

Translated from Izvestiia Akademii Nauk SSSR, Otdel. Tekh. Nauk {Bulletin of the Academy of Sciences USSR, Div. Tech. Sci.), 1958, no. 7. Translated by B. G. Karpov under the auspices of U. S. Army Ordnance, Ballistic Research Laboratories, Aberdeen Proving Ground, Md. This translation was supplied to the American Rocket Society by C. H. Murphy, Chief, Free Flight Aerodynamics Branch, Ballistic Research Laboratories. A. L. GONOR

Ballistic Research Rockets With Particular Reference to Black Knight

The 1172nd Main Lecture to be given before the Society and the 41st to be held at a Branch centre “Ballistic Research Rockets with Particular Reference to Black Knight” was given under the auspices of the Luton Branch on 1st December 1960. Mr. F. H. Pollicutt, F.R.Ae.S., Chairman of the Luton Branch opened the meeting by welcoming the President, Dr. E. S. Moult, C.B.E., B.Sc., F.R.Ae.S., M.I.Mech.E., the other members of the Council of the Main Society who were present, and representatives from the Bristol, Birmingham and Wolverhampton, Coventry, Christchurch, Derby, Hatfield, Halton, Henlow, Preston and Weybridge Branches. He then asked Dr. Moult to preside over the rest of the proceedings.Dr. Moult expressed his pleasure at being present on this occasion–the second time a Main Society Lecture had been presented at the Luton Branch–and then introduced the Lecturer, Mr. D. J. Lyons. Mr. Lyons took his degree in Aeronautical Engineering at Queen Mary College and subsequently joined the Wind Tunnel staff at Farnborough. During the war he became a flying instructor in the R.A.F. and later rejoined the Aerodynamics Flight Section at. the R.A.E. For the next ten years Mr. Lyons was engaged in Flight Research on stability and control. In 1951 he was appointed Superintendent of the Experimental Projects Division in the Guided Weapons Department and in 1955 was promoted to his present position as Senior Superintendent of the Ballistic Missile Group of the Guided Weapons Department. He had been responsible from the Ministry aspect for the research and development connected with the Black Knight and Blue Streak Missile systems.

Aerodynamics of Supersonic Flight

<i>Aerodynamics of Supersonic Flight</i>

Biology and physics of locust flight. III. The aerodynamics of locust flight

A proper understanding of how locusts fly must be based upon knowledge of how the wings are moved. A desert locust was suspended from a balance and placed in an air stream so that it flew under nearly the same conditions as during natural forward flight. Four stroboscopic slow-motion films were selected for measurement. The movements of the wings, i.e. their positions, velocities and accelerations, were then calculated in sufficient detail to show how these quantities vary with time during one complete wing stroke. The aerodynamic lift and drag of the entire natural wing were measured in a wind tunnel with the wing arranged in different positions relative to the flow. By placing it in the boundary layer of the tunnel, the wind speed was graded from tip to base in approximately the same way as during the actual flight. There is therefore no error due to scale effect or to the induced drag. In most respects the wings resemble ordinary, slightly cambered airfoils. Their characteristics are given as polar diagrams. The kinematic and aerodynamic analyses make it possible to calculate the forces which act upon the locust at any instant of time. It is here necessary to presuppose that the non-stationary flight situations are essentially similar to a sequence of stationary situations. For locusts, this presupposition is justified: (i) from theoretical estimates of the quantitative effect of non-stationary flow; and (ii) from control measurements of the average thrust and lift produced during flight. It was found that the calculated vertical force, when averaged over an entire wing stroke, equalled the average reduction in body weight, asmeasureddirectly on the flight balance. Similarly, the average thrust of the wings corresponded to the drag of the body. The analysis shows how the aerodynamic forces varyduringthe wing stroke. The hindwings are responsible for about 70 % of the total lift and thrust. About 80 % of the lift is produced during the downstroke. During flight at normal lift the angles of attack (middle part of wing) are small during the upstroke and vary between 10 and 15° during the downstroke. When the lift was larger or smaller than the body weight these figures increased or decreased respectively. The forewings are peculiar in two ways: (i) during the middle part of the downstroke a true flap (the vannus) is put into action; (ii) during the upstroke the proximal part has a Z-shaped cross-section and gives but little lift and drag. The hindwings are characteristic in that the posterior part (vannus) is flexible and becomes moulded by the wind, increasing the angle of attack at which stalling occurs to about 25°. Since both the movements of the wings relative to the body and the aerodynamic forces are known at any instant, the exchange of power with the surrounding air can be calculated. The moments of inertia of the wing mass being known, the power for accelerating the wings can also be estimated. The sum of these contributions is the power which passes the wing fulcrum; this estimate is used in a later paper (part IX) where the energetics of flight is discussed in detail. The diagrams are correct to scale. The restriction of freedom caused by the suspension is discussed, together with the possible errors of a stationary analysis.

Elements of Detail Design

British aircraft engineering has reached a stage in its development when one is safe in saying that:—(a) The aerodynamics of flight is appreciated and understood to a satisfactory extent;(b) The methods of determining the loads likely to be present in the primary structural members are reliable;(c) The change over from wood to metal construction is, for all practical purposes, a reality; and(d) Suitable ferrous and non-ferrous materials of construction available for use by aircraft constructors have been standardised and proved to be reliable and consistent in quality.