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A spin-tunnel investigation of the spin and recovery characteristics of a 1/25-scale model to the General Dynamics F-16XL aircraft was conducted in the Langley Spin Tunnel. Tests included erect and inverted spins at various symmetric and asymmetric loading conditions. The required size of an emergency spin-recovery parachute was determined.
Numerical techniques for obtaining the trigger altitude of the Solar Mesosphere Explorer (SME) are detailed. The SME has a pair of fixed horizon sensors for attitude determination and initiation of the data acquisition procedures for measuring ozone concentrations at the limb. The spacecraft spin rate is calculated as each of the horizon sensors marks the limb with a pulse telemetered to the ground. A best fit spin dynamics model that takes into account the history of the satellite spin angle and all disturbances to the spin is described. Analyses show that the trigger altitude is calculated to an accuracy of 1.5-2.0 km. A significant indicator of the limb altitude is the stratospheric temperature at the 5 mb pressure level.
Spin tests have been conducted in the Langley free-spinning tunnel on a 1/16-scale model of the McDonnell XP-85 airplane with the normal X-tail replaced with a short-coupled conventional tail arrangement. The effect of the conventional tail arrangement and the effects of various modifications upon the spin and recovery characteristics of the model were determined. The results of the tests indicated that installation of the conventional tail arrangement wil not provide satisfactory recoveries from spins of the airplane. Satisfactory recoveries will be obtainable, however, either by installing in addition a very large ventral fin (17.94 sq ft, full-scale) below the tail or by decreasing the width of the fuselage and making it flat sided rearward of the wing trailing edge.
Effects of pointed nose on spin characteristics of fighter aircraft model and correlation of free flight test results with theoretical data
The investigation described in this report was made to determine the change in aerodynamic forces and moments produced by split flaps in a steady spin. The test were made with the spinning balance in the NACA 5-foot vertical wind tunnel. A low-wing monoplane model was tested with and without the split flaps in 12 spinning attitudes chosen to cover the probable spinning range. The changes in coefficients produced by adding the split flaps are given for longitudinal force, normal force, and rolling and yawing moments about body axes. The results obtained indicate that the use of split flaps on an airplane is unlikely, in any case, to have much beneficial effect on a spin, and it might make the spin dangerous. The change in the spin will depend upon the aerodynamic and inertia characteristics of the particular airplane. A dangerous condition is most likely to be attained with airplanes which are statically stable in yaw in the spinning attitude and which have large weights distributed along wings.
A spin-tunnel investigation of a 1/26 scale model of the Douglas XTB2D-1 airplane has been conducted in the Langley 20-foot free-spinning tunnel. The effects of control settings and movements upon the erect- and inverted-spin and recovery characteristics of the model were determined for various loading conditions. Tests were also performed to determine the effects of various tail modifications. The investigation included emergency spin-recovery parachute tests as well as crew-escape and rudder- and elevator-force tests. All tests were performed at an equivalent spin altitute of 20,000 feet. The recovery characteristics of the model in the original design were found to be unsatisfactory. Installation of a large ventral fin, installation of tip fins on the horizontal tail, or installation of a small ventral fin in combination with antispan fillets and a spanwise extension of the horizontal-tail surfaces satisfactorily improved the recovery characteristics of the model.
Powered, radio-controlled flight tests were conducted on a 1/4-scale model of a spin-resistant trainer configuration to determine the stall departure and spin resistance characteristics provided by an outboard wing leading-edge droop modification. The model was instrumented to provide quantitative as well as qualitative information on flight characteristics. Flight test results indicated that the unmodified configuration (wing leading-edge droop off) exhibited an abrupt, uncontrollable roll departure at the stall. With the outboard wing leading-edge droop installed, the modified configuration exhibited flight characteristics that were resistant to stall departure and spin entry. The stall departure and spin resistance characteristics of the modified configuration were demonstrated in flight maneuvers that included idle-power stalls, full-power stalls, sideslip stalls, and accelerated stalls.
An investigation of the spin and recovery characteristics of a 1/24-scale model of the McDonnell XP-88 airplane has been conducted in the Langley 20-ft free-spinning tunnel. Results of tests with a conventional tail have been previously reported; the results presented herein are for the model with a vee tail installed. The effects of control settings and movements on the erect and inverted spin and recovery characteristics of the model. In the normal loading were determined. Tests of the model in the long-range loading also were made. The investigation included leading-edge-flap, spin-recovery-parachute, and rudder-pedal-force tests. The recovery characteristics of the model were satisfactory for the normal loading. Deflecting the leading-edge flaps improved recoveries. The results indicated that with the external wing tanks installed (long-range loading) recoveries may be poor and, therefore, if a spin is inadvertently entered in this condition the tanks should be jettisoned if recovery does not appear imminent immediately after it is attempted. A 10-foot spin-recovery tail parachute with a towline 40 feet long and a drag coefficient of 0.63 was found to be effective for spin recovery. The rudder pedal force required for spin recovery was indicated to be within the capabilities of the pilot.
One of the many design challenges of this project is predicting the thermal effects due to the environment inside the vacuum chamber on the turntable and spin motor spindle assembly. The objective of the study is to model the spin motor using the computer program System Improved Numerical Differencing Analyzer (SINDA). By formulating the appropriate input information concerning the motor's geometry, coolant flow path, material composition, and bearing and motor winding characteristics, SINDA should predict temperatures at various predefined nodes. From these temperatures, hopefully, one can predict if the coolant flow rate is sufficient or if certain mechanical elements such as bearings, O ring seals, or motor windings will exceed maximum design temperatures.
The dependence of the spin-up system efficiency on each geometrical parameter of the spin-up channel and the exhaust passage of the Gravity Probe-B (GPB) is individually investigated. The spin-up model is coded into a computer program which simulates the spin-up process. Numerical results reveal optimal combinations of the geometrical parameters for the ultimate spin-up performance. Comparisons are also made between the numerical results and experimental data. The experimental leakage rate can only be reached when the gap between the channel lip and the rotor surface increases beyond physical limit. The computed rotating frequency is roughly twice as high as the measured ones although the spin-up torques fairly match.
An investigation of the spin and recovery characteristics of a 1/24-scale model of the Grumman XF9F-2 airplane with wing-tip tanks installed has been conducted-in the Langley 20-foot free-spinning tunnel. The effects of control settings and movements on the erect spin and recovery characteristics of the model for a range of possible loadings of the tip tanks were determined. Spin and recovery characteristics without tanks were determined in a previous investigation. The model results indicated that the airplane spins will generally be oscillatory and that recoveries will be satisfactory for all loadings by normal recovery technique (full rudder reversal followed approximately one-half turn later by moving the elevator down). The rudder force necessary for recovery should be within the physical capability of the pilot but the elevator force may be excessive so that some type of balance or booster might be necessary, or it might be necessary to jettison the wing-tip tanks.
An investigation was conducted in the Langley Spin Tunnel of the spin and spin-recovery characteristics of a 1/15-scale model of an Australian trainer airplane. The invesigation included erect and inverted spins; configuration variables such as a long tail, fuselage strakes, 20 deg. elevator cutouts, and rudder modifications; and determination of the parachute size for emergency spin recovery. Also included in the investigation were wing leading-edge modifications to evaluate Reynolds number effects. Results indicate that the basic configuration will spin erect at an angle of attack of about 63 deg. at about 2 to 2.3 seconds per turn. Recovery from this spin was unsatisfactory by rudder reversal or by rudder reversal and ailerons deflected to full with the spin. The elevators had a pronounced effect on the recovery characteristics. The elevators-down position was very adverse to recoveries, whereas the elevators-up position provided favorable recovery effects. Moving the vertical tail aft (producing a long tail configuration) improved the spin characteristics, but the recoveries were still considered marginal. An extension to the basic rudder chord and length made a significant improvement in the spin and recovery characteristics. Satisfactory recoveries were obtained by deflecting the rudder to full against the spin and the elevators and ailerons to neutral.
In accordance with the request of the Materiel Division, Army Air Corps, as contained in their letter to the NACA, dated August 11, 1941, tests were performed to determine the spin characteristics of a 1/20-scale model of the Bell XP-39E airplane. The effects of control dispositions were investigated, and brief tests were made with the mass distribution and center-of-gravity location varied moderately. The effect of installing an external 614-poound demolition bomb was determined, as was also the effect of modifying the tail.
An investigation of the spin and recovery characteristics of a 1/24-scale model of the McDonnell XP-88 airplane has been conducted in the Langley 20-foot free-spinning tunnel. The effects of control settings and movements on the erect and inverted spin and recovery characteristics of the model in the normal loading were determined. Tests of the model in the long-range loading also were made. The investigation included tail-modification, spin-recovery parachute, pilot-escape, and rudder-pedal-force tests. Recoveries were generally satisfactory for spins in the normal loading provided the ailerons were not held against the spin. Satisfactory recoveries were obtained regardless of the aileron setting when the leading-edge flaps were deflected and normal recovery technique was used or when the horizontal tail was raised 70 inches, full scale. Recoveries were rapid from all inverted spins obtained. In the long-range loading with tanks on, it may be necessary to jettison the tanks in order to obtain recovery. A 12.0-foot spin-recovery parachute at the tail or a 4.0-foot parachute opened on the outer wing tip (drag coefficient of 0.66) was found to be effective for recoveries from demonstration spins. Test results showed that in an emergency the pilot should attempt to escape from the outboard side of the spinning airplane. The rudder-pedal forces in a spin were indicated to be within the capabilities of the pilot.
It is shown that the Goedel metric for a rotating cosmology is compatible with the self-consistent formulation of the Einstein-Cartan metric-torsion theory for a spinning fluid. In the model presented, the only changes are that the cosmological constant becomes slightly more negative, and the sense of rotation is flipped. If the Goedel model were a viable model, experimentally it would be difficult to distinguish between the two models unless the spin density could be measured directly.
An investigation has been made of a 1/28-scale model of the Grumman A-6A airplane in the Langley spin tunnel. The erect spin and recovery characteristics of the model were determined for the flight design gross weight loading and for a loading with full internal fuel and empty external wing fuel tanks. The effects of extending slats and deflecting flaps were investigated. Inverted-spin and recovery characteristics of the model were determined for the flight design gross weight loading. The size of the spin-recovery tail parachute necessary to insure satisfactory spin-recovery was determined, and the effect of firing wing-mounded rockets during spins was investigated.
An investigation has been completed in the Langley 20-foot free-spinning tunnel on a l/18-scale model of the Ryan X-13 airplane to determine its spin, recovery, and tumbling characteristics, and to determine the minimum altitude from which a belly landing could be made in case of power failure in hovering flight. Model spin tests were conducted with and without simulated engine rotation. Tests without simulated engine rotation indicated two types of spins: one, a slightly oscillatory flat spin; and the other, a violently oscillatory spin. Tests with simulated engine rotation indicated that spins to the left were fast rotating and steep and those to the right were slow rotating and flat. The optimum technique for recovery is reversal of the rudder to against the spin and simultaneous movement of the ailerons to full with the spin followed by movement of the elevators to neutral after the spin rotation ceases. Tumbling tests made on the model indicated that although the Ryan X-13 airplane will not tumble in the ordinary sense (end-over-end pitching motion), it may instead tend to enter a wild gyrating'motion. Tests made to simulate power failure in hovering flight by dropping the model indicated that the model entered what appeared to be a right spin. An attempt should be made to stop this motion immediately by moving the rudder to oppose the rotation (left pedal), moving the ailerons to with the spin (stick right), and moving the stick forward after the spin rotation ceases to obtain flying speed for pullout. The minimum altitude required for a belly landing in case of power failure in hovering flight was indicated to be about 4,200 feet.
The spin and recovery characteristics of a 1/13-scale model of the NASA AD-1 oblique-wing research aircraft at wing-skew positions of 0, 25, 45, and 60 deg (right wing forward) were investigated. Spins were obtained for all wing-skew positions tested. For the unskewed wing position, two spin modes were possible. One spin mode was very steep and recoveries were obtained within 1 turn or less by rudder reversal. The second spin mode was flat and fast; the angle of attack was about 75 deg and the spin rate was about 145 deg/sec (2.5 seconds per turn). For the skewed wing positions, spins were obtained only in the direction of the forward-skewed wing (right wing forward). No spins were obtained to the left when the wing was skewed with the right wing forward. Recoveries should be attempted by deflecting the rudder to full against the spin, the ailerons to full with the spin, and movement of the wings to 0 deg skew. If the wing is skewed, the recovery may not be effected until the wing skew approaches 0 deg.