ALBERT

Description: An investigation has been made at Mach numbers of 1.61 and 2.01 and Reynolds numbers from 1.7 X 10 to 7.6 X 10 to determine the pressure distributions over a 60 deg. delta wing having 20 different control configurations. Measurements were made at angles of attack from O deg to 15 deg for control deflections from -30 deg to 30 deg. This report presents the complete tabulated pressure data for the range of test conditions.

Description: Tests have been made in the Langley 4- by 4-foot supersonic pressure tunnel at Mach numbers of 1.41, 1.61, and 2.01 to determine the static longitudinal stability and control characteristics of various arrangements of the Grumman F11F-1 airplane. Tests were made of the complete model and various combinations of its component parts and, in addition, the effects of various body modifications, a revised vertical tail, and wing fences on the longitudinal characteristics were determined. The results indicate that for a horizontal-tail incidence of -10 deg the trim lift coefficient varied from 0.29 at a Mach number of 1.61 to 0.23 at a Mach number of 2.01 with a corresponding decrease in lift-drag trim from 3.72 to 3.15. Stick-position instability was indicated in the low-supersonic-speed range. A photographic-type nose modification resulted in slightly higher values of minimum drag coefficient but did not significantly affect the static stability or lift-curve slope. The minimum drag coefficient for the complete model with the production nose remained essentially constant at 0.047 throughout the Mach number range investigated.

Description: This paper presents the results of an investigation of sting-support interference on afterbody drag at transonic speeds. Stings with varying diameter, cone angle, and cylindrical length were tested at the rea r of a model with various afterbody shapes. The data were obtained at an angle of attack of O deg. and at Mach numbers from 0.80 to 1.10. It was found that, in general, the addition of a sting caused a drag reduction. A method is presented whereby approximate sting-interferen ce corrections may be made to models with afterbodies and sting suppo rts of similar size and scale to those of this paper provided the bou ndary layer is turbulent at the model base and the Reynolds numbers a re of the same order of magnitude. Reynolds number of the tests prese nted varied from 15.0 x 10 (exp 6) to 17.4 x 10 (exp 6) based on body length. Sting effects from this investigation are compared with data of jet effects on the same afterbodies. The results of this comparis on indicate that for the more gradually contoured afterbodies, a stin g shape can be found which will duplicate the jet effects, but that f or blunt afterbodies no solid sting shape will duplicate the jet effe cts.

Description: A flight investigation was conducted to determine the effect of jet exhaust on the drag, trim characteristics, and afterbody pressures on a 0.125-scale rocket model of the McDonnell F-101A airplance. Power-off data were obtained over a Mach number range of 1.04 to 1.9 and power-on data were obtained at a Mach number of about 1.5. The data indicated that with power-on the change in external drag coefficient was within the data accuracy and there was a decrease in trim angle of attack of 1.27 degrees with a corresponding decrease of 0.07 in lift coefficient. Correspondingly, pressure coefficients on the side and bottom of the fuselage indicated a positive increment near the jet exit. As the distance downstream of the jet exit increased, the increment on the bottom of the fuselage increased, whereas the increments on the side decreased to a negative peak.

Description: The technical memorandum briefly summarizes the growth of interest in aeroelastic phenomena as aircraft speed increased and wing designs changed for faster aircraft. Different types of aircraft vibrations are then introduced, and the mathematical basis for the theory behind them is described. Special attention is given to static oscillations, wing flutter, and the flutter of skin panels. The last section of the memorandum deals with the prevention of flutter by design specifications.

Description: An experimental investigation of the internal-flow conditions of a J71 experimental turbine equipped with 97-percent-design stator areas was conducted at equivalent design speed and near equivalent design work. The results of the investigation indicate that the stage work distribution closely approximates design, the actual distribution being 44.1, 33.4, and 22.5 percent for the first, second, and third stages, respectively. The first-, second-, and third-stage efficiencies were 0.894, 0.858, and 0.792, respectively. The first and second stages exhibited loss regions near the hub and tip at the rotor blade outlets. The hub loss region is attributed to stator secondary flows, and a contributing factor to the tip loss region may be the high design diffusion on the rotor blade suction surface near the tip. The loss in the third stage is appreciably greater than that in the first or second stage. The fact that the third rotor is unshrouded and has a nominal tip clearance of 0.120 inch may contribute to the higher loss in the tip region of the third stage.

Description: An investigation has been conducted in the Langley 20-foot free-spinning tunnel on a l/19-scale model of the North American T-28C airplane to determine the spin and recovery characteristics. The T-28C airplane is similar to the T-28B airplane except for slight modifications for the arresting hook. The lower rear section of the fuselage was cut out and, consequently, the lower part of the rudder was removed to make a smooth fairing with the fuselage. The T-28B airplane had good recovery characteristics; but these modifications, along with the addition of gun packages on the wings, led to poor and unsatisfactory spin-recovery characteristics during demonstration spins of the T-28C airplane. Model test results indicated that without the gun packages installed, satisfactory recoveries could be obtained if the elevators were held full back while the rudder was fully reversed and the ailerons were held neutral. However, with the addition of gun packages to the wings and the corresponding change in loading, recoveries were considered unsatisfactory. Recoveries attempted by using a larger chord or larger span rudder were improved very slightly, but were still considered marginal or unsatisfactory. Strakes placed on the nose of the model were effective in slowing the spin rotation slightly and, in most instances, decreased the turns for recovery slightly. Recovery characteristics were slightly marginal for the full fuel loading when strakes and the extended-chord rudder were installed; but with the wing fuel partly used, recovery characteristics were again considered unsatisfactory or, at least, definitely on the marginal side. The optimum control technique for recovery is movement of the rudder to full against the spin with the stick held full back (elevators full up) and the ailerons held neutral, followed by forward movement of the stick only after the spin rotation ceases. Inverted-spin test results indicate that the airplane will spin steep and fast and that recovery by full rudder reversal will be satisfactory if the ailerons are held neutral.

Description: An investigation has been conducted in the 27- by 27-inch preflight jet of the Langley Pilotless Aircraft Research Station at Wallops Island, Va., of the release characteristics of a dynamically scaled streamlined-type internally carried store from a simulated bomb bay at Mach numbers M(sub o) of 0.8, 1.4, and 1.98. A l/17-scale model of the Republic F-105 half-fuselage and bomb-bay configuration was used with a streamlined store shape of a fineness ratio of 6.00. Simulated altitudes were 3,400 feet at M(sub o) = 0.8, 3,400, and 29,000 feet at M(sub o) = 1.4, and 29,000 feet at M(sub o) = 1.98. At supersonic speeds, high pitching moments are induced on the store in the vicinity of the bomb bay at high dynamic pressures. Successful ejections could not be made with the original configuration at supersonic speeds at near sea-level conditions. The pitching moments caused by unsymmetrical pressures on the store in a disturbed flow field were overcome by replacing the high-aspect-ratio fin with a low-aspect-ratio fin that had a 30-percent area increase which was less subject to aeroelastic effects. Release characteristics of the store were improved by orienting the fins so that they were in a more uniform flow field at the point of store release. The store pitching moments were shown to be reduced by increasing the simulated altitude. Favorable ejections were made at subsonic speeds at near sea-level conditions.

Description: A negligible effect on turbine efficiency and only a small decrease in turbine weight flow were observed when the J71 experimental turbine with 97-percent-design stator areas was modified to include shrouding of the third-stage rotor.

Description: Information on landing gear stresses is presented on the following: vibratory phenomena, tangential forces applied to landing gear, fore and aft oscillations of landing gears, examples of fatigue failures, vibration calculations, and improvement of existing test equipment.

Description: The National Advisory Committee for Aeronautics has conducted a flight test of a model approximating the McDonnell F3H-lN airplane configuration to determine its pitch-up and buffet boundaries, as well as the usual longitudinal stability derivatives obtainable from the pulsed- tail technique. The test was conducted by the freely flying rocket- boosted model technique developed at the Langley Laboratory; results were obtained at Mach numbers from 0.40 to 1.27 at corresponding Reynolds numbers of 2.6 x 10(exp 6) and 9.0 x 10(exp 6). The phenomena of pitch-up, buffet, and maximum lift were encountered at Mach numbers between 0.42 and 0.85. The lift-curve slope and wing-root bending-moment slope increased with increasing angle of attack, whereas the static stability decreased with angle of attack at subsonic speeds and increased at transonic speeds. There was little change in trim at low lift at transonic speeds.

Description: A ditching investigation was made of a l/l2-scale dynamically similar model of the Douglas F4D-1 airplane to study its behavior when ditched. The model was landed in calm water at the Langley tank no. 2 monorail. Various landing attitudes, speeds, and configurations were investigated. The behavior of the model was determined from visual observations, acceleration records, and motion-picture records of the ditchings. Data are presented in tables, sequence photographs, time-history acceleration curves, and attitude curves. From the results of the investigation, it was concluded that the airplane should be ditched at the lowest speed and highest attitude consistent with adequate control (near 22 deg) with landing gear retracted. In a calm-water ditching under these conditions the airplane will probably nose in slightly, then make a fairly smooth run. The fuselage bottom will sustain appreciable damage so that rapid flooding and short flotation time are likely. Maximum longitudinal deceleration will be about 4g and maximum normal acceleration will be about 6g in a landing run of about 420 feet, In a calm-water ditching under similar conditions with the landing gear extended, the airplane will probably dive. Maximum longitudinal decelerations will be about 5-1/2g and maximum normal accelerations will be about 3-1/2g in a landing run of about 170 feet.

Description: This paper contains tail and hull loads data obtained in an investigation of a l/15-scale model of the Goodyear XZP5K airship. Data are presented in the form of tabulated pressure coefficients over a pitch and yaw range of +/-20 deg and 0 deg to 30 deg respectively, with various rudder and elevator deflections. Two tail configurations of different plan forms were tested on the model. The investigation was conducted in the Langley full-scale tunnel at a Reynolds number of approximately 16.5 x 10(exp 6) based on hull length, which corresponds to a Mach number of about 0.12.

Description: An investigation has been completed in the Langley 20-foot free-spinning tunnel on a l/24-scale model of the Grumman F11F-1 airplane to determine its spin and recovery characteristics. An interim report, Research Memorandum SL55G20, was published earlier and the present report concludes the presentation of results of the investigation. Primarily, the present report presents results obtained with engine gyroscopic moments simulated on the model. Also, the current results were obtained with a revised larger vertical tail recently incorporated on the airplane. It was difficult to obtain developed spins on the model when the spin direction was in the same sense as that of the engine rotation (right spin on the airplane). The developed spins obtained were very oscillatory and the recoveries were unsatisfactory. These results were similar to those previously reported for which engine rotation was not simulated. When the spin direction was in the opposite sense (left spin on the airplane), however, developed spins were readily obtainable. Recoveries from these spins also were unsatisfactory. Satisfactory recoveries were obtained on the model, however, when rudder reversal was accompanied by extension of small canards near the nose of the airplane or by deflection of the horizontal tail differentially with the spin.

Description: An investigation has been made in the Langley 4- by 4-foot supersonic pressure tunnel at a Mach number of 1.41 to determine the aerodynamic characteristics of an 0.03-scale model of the Avro CF-105 airplane. The investigation included the determination of the static longitudinal and lateral stability, the control and the hinge-moment characteristics of the elevator, the aileron, and the rudder, as well as the vertical-tail-load characteristics. The results indicated a minimum drag coefficient of about 0.0270, and a maximum trimmed lift-drag ratio of about 4.25 which occurs at a lift coefficient of 0.16. The directional stability decreased with increasing angle of attack until a region of static instability occurred above an angle of attack of about 9 deg.

Description: As a part of this investigation, the acceleration characteristics of the engine, using the standard engine fuel-control system, were obtained for conditions simulating flight at altitudes of 35,000 and 50,000 feet with a flight Mach number of 0.4. Rapid and wave-off type accelerations were made at each flight condition, and the transient performance of the engine was recorded with a multiple-channel oscillograph. The parameters are presented graphically in the form of time histories, augmented by short segments of the oscillograph recordings, in order to more completely describe the behavior of the engine parameters when surge was encountered.

Description: This document is a compilation of papers presented at the Conference on the Progress of the X-15 project held at the Langley Aeronautical Laboratory on 25-26 October 1956. The conference was held by the Research Airplane Committee of the U. S. Air Force, the U. S. Navy, and the National Advisory Committee for Aeronautics to report on the technical status of this research airplane. The papers were presented by members of the staffs of North American Aviation, Inc., Reaction Motors, Inc., and NACA.

Description: This report is a complilation of practical rules, derived at the same time from theory and from experience, intended to guide the aeronautical engineer in the design of flutter-free airplanes. Rules applicable to the wing, the ailerons, flaps, tabs,tail surfaces, and fuselage are discussed.

Description: An investigation has been made in the Langley 4 by 4-foot supersonic pressure tunnel at Mach numbers of 1.82 and 2.01 to determine the longitudinal and lateral static-stability characteristics of a 0.04-scale model of the Lockheed F-104A airplane. The effects of a modified vertical tail, several ventral-fin arrangements, and several external store arrangements were also determined. The tests were made at Reynolds numbers of 1.02 (exp 6) and 1.382 (exp 6), respectively, based on the wing mean geometric chord. The tests were made of combined angles of attack and sideslip that varied from about -4 deg. to about 20 deg.

Description: This report presents the results of tests of a .35-scale model of the Bell P-39N-1 airplane. Included are the longitudinal-stability and -control characteristics of the airplane as indicated by tests of the model equipped with each of two different sets of elevators. The results indicate good longitudinal stability and control throughout the speed range encounterable in flight. The variation of estimated stick force with speed was less when the model was equipped with elevators constructed to the theoretical design dimensions than when equipped with elevators as built to scale from measurements of the corresponding parts of the actual airplane. The predicted stick forces required to produce the normal accelerations attainable in flight are within the limits specified by the Army Air Forces.

Description: Investigations with a view to increasing the lift coefficient of a wing, without greatly increasing the C(sub x min), are chiefly related to the important question of the maximum speed range.

Description: This note discusses the limitations of the conventional tank test of a seaplane model. The advantages of a complete test, giving the characteristics of the model at all speeds, loads, and trim angles in the useful range are pointed out. The data on N.A.C.A. Model No.11, obtained from a complete test, are presented and discussed. The results are analyzed to determine the best trim angle for each speed and load. The data for the best angles are reduced to non-dimensional form for ease of comparison and application. A practical problem using the characteristics of model no.11 is presented to show the method of calculating the take-off time and run of a seaplane from these data.

Description: Since the recent more or less extensive adoption of high-lift flaps on airplane wings, the problem of providing satisfactory lateral control without sacrificing a part of the span of the flaps has become one of some importance. The difficulties have been largely a matter of obtaining satisfactory rolling moments with a smoothly graduated action, together with sufficiently small control forces throughout the entire speed range. As part of an investigation including several different lateral-control arrangements to be used with split flaps, the tests reported in this paper were made on one arrangement in which conventional ailerons of narrow chord are used, and a split flap is retracted into the under surface of th wing forward of th ailerons. When the flap is retracted, the arrangement is as sketched in figure 1(a). If a simple form of split flap were used, hinged at its forward edge, the appearance when deflected would be as shown in figure 1(b). The flap if deflected with its leading edge remaining in this forward position would give somewhat less than three fourths of the lift increase of the same flap in the usual rear position. (See reference 1.). If, as shown in figure 1(c), the split flap ahead of th aileron is moved to the rear as the trailing=edge portion is deflected downward, a double advantage is obtained. The deflected flap can be located in the most effective region for high lift (reference 1), and the force required to deflect the flap is reduced. This is the arrangement used in the present tests.