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NASA NTRS2015

Space Shuttle Rudder Speed Brake Actuator-A Case Study Probabilistic Fatigue Life and Reliability Analysis

The U.S. Space Shuttle fleet was originally intended to have a life of 100 flights for each vehicle, lasting over a 10-year period, with minimal scheduled maintenance or inspection. The first space shuttle flight was that of the Space Shuttle Columbia (OV-102), launched April 12, 1981. The disaster that destroyed Columbia occurred on its 28th flight, February 1, 2003, nearly 22 years after its first launch. In order to minimize risk of losing another Space Shuttle, a probabilistic life and reliability analysis was conducted for the Space Shuttle rudder/speed brake actuators to determine the number of flights the actuators could sustain. A life and reliability assessment of the actuator gears was performed in two stages: a contact stress fatigue model and a gear tooth bending fatigue model. For the contact stress analysis, the Lundberg-Palmgren bearing life theory was expanded to include gear-surface pitting for the actuator as a system. The mission spectrum of the Space Shuttle rudder/speed brake actuator was combined into equivalent effective hinge moment loads including an actuator input preload for the contact stress fatigue and tooth bending fatigue models. Gear system reliabilities are reported for both models and their combination. Reliability of the actuator bearings was analyzed separately, based on data provided by the actuator manufacturer. As a result of the analysis, the reliability of one half of a single actuator was calculated to be 98.6 percent for 12 flights. Accordingly, each actuator was subsequently limited to 12 flights before removal from service in the Space Shuttle.

Rudder↗
NASA NTRS1976

Wind tunnel tests of the dynamic characteristics of the fluidic rudder

The fourth phase is given of a continuing program to develop the means to stabilize and control aircraft without moving parts or a separate source of power. Previous phases have demonstrated the feasibility of (1) generating adequate control forces on a standard airfoil, (2) controlling those forces with a fluidic amplifier and (3) cascading non-vented fluidic amplifiers operating on ram air supply pressure. The foremost objectives of the fourth phase covered under Part I of this report were to demonstrate a complete force-control system in a wind tunnel environment and to measure its static and dynamic control characteristics. Secondary objectives, covered under Part II, were to evaluate alternate configurations for lift control. The results demonstrate an overall response time of 150 msec, confirming this technology as a viable means for implementing low-cost reliable flight control systems.

Belsterling, C. A.↗
NASA NTRS1983

Determination of Elevator and Rudder Hinge Forces on the Learjet Model 55 Aircraft

The empennage structure on the Learjet 55 aircraft was quite similar to the empennage structure on earlier Learjet models. However, due to an important structural change in the vertical fin along with the new loads environment on the 50 series aircraft, a structural test was required on the vertical fin, but the horizontal tail was substantiated by a comparative analysis with previous tests. NASTRAN analysis was used to investigate empennage deflections, stress levels, and control surface hinge forces. The hinge force calculations were made with the control surfaces in the deflected as well as undeflected configurations. A skin panel buckling analysis was also performed, and the non-linear effects of buckling were simulated in the NASTRAN model to more accurately define internal loads and stress levels. Comparisons were then made between the Model 55 and the Model 35/36 stresses and internal forces to determine which components were qualified by previous tests. Some of the methods and techniques used in this analysis are described.

Boroughs, R. R.↗
NASA NTRS1921

Measurements of Rudder Moments on an Airplane During Flight

Tests indicated that: 1) C airplanes with two struts are extremely susceptible to aileron maneuvers, slight alterations of the aileron sufficing to compensate great unequalized moments; 2) great unequalized moments can be produced or neutralized by the unequalized alternation of the angle of attack below the outer and inner struts. Adjustment below the outer strut is the more effective of the two. 3) When a load of bombs is suspended beyond the center of the airplane, below the wings, the bombs need not be dropped simultaneously. 4) The propeller wash of a wide open engine has considerable influence on the position and operation of the elevator. The elevator is more susceptible in flight with the engine running than in gliding flight. 5) Adjustable tail planes are not advisable for D airplanes, nor for the C type, but they are, on the other hand, to be recommended for large size and giant airplanes in which the center of gravity changes during flight. 6) The aileron values obtained by wind tunnel measurements are about 10 percent too low, though otherwise applicable. For the elevator, the results of such measurements should be taken as mean values between flight with the engine running and gliding flight.

Heidelberg, Ing V↗
NASA NTRS1962

Effects of Booster Transition Section and Rudder Deflection on the Low-Angle-of-Attack Static Stability of a Winged Reentry Vehicle at Mach Numbers of 10.8 and 17.8 in Helium

An investigation has been carried out to obtain aerodynamic stability and control data on a model of a winged reentry vehicle at Mach numbers of 10.8 and 17.8 in helium. The effects of a booster transition section on the static stability were obtained at angles of attack from -5 deg to 15 deg and at angles of sideslip from -5 deg to 10 deg at an angle of attack of 0 deg. Directional control data were also obtained at an angle of attack of 0 deg for sideslip angles from -5 deg to 10 deg. No detailed analysis of the data has been made.

Ladson, Charles L.↗
NASA NTRS1948

Supplementary Investigation in the Langley 20-Foot Free-Spinning Tunnel of the Spin and Recovery Characteristics of a 0.057-Scale Model of the Chance Vought XFU-1 Airplane, Ted No. NACA DE 311

An investigation has been conducted in the Langley 20-foot free-spinning tunnel to determine the effects of decreasing the rudder deflection, of decreasing the rudder span, and of differential rudder movements on the spin and recovery characteristics of a 0.057-scale model of the Chance Vought XF7U-1 airplane. The results indicated that decreasing the rudder span or the rudder deflections, individually or jointly, did not seriously alter the spin or recovery characteristics of the model; and recovery by normal use of controls (full rapid rudder reversal followed l/2 to 1 turn later by movement of the stick forward of neutral) remained satisfactory. Linking the original rudders so that the inboard rudder moves from full with the spin to neutral while the outboard rudder moves from neutral to full against the spin will also result in satisfactory spin and recovery characteristics. Calculations of rudder-pedal forces for recovery showed that the expected forces would probably be within the capabilities of a pilot but that it would be advisable to install some type of boost in the control system to insure easy and rapid movement of the rudders.

Berman, Theodore↗
NASA NTRS1945

Wind-Tunnel Tests of a 1/6-Scale Model of Republic XF-12 Vertical Tail with Stub Fuselage and Stub Horizontal Tail

A 1/6-scale model of the Republic XF-12 vertical tail with stub fuselage and stub horizontal tail was tested in the Langley stability tunnel to determine the aerodynamic characteristics of the model, The investigation included a study of the effects of boundarylayer thickness, rudder area, and cover-plate alinement on the aerodynamic characteristics. Tuft studies were made in the vicinity of the junction of the vertical and stub horizontal tails. The results of the investigation indicated that the flow in the vicinity of the junction of the vertical and stub horizontal tails was only slightly improved by the addition of a fillet. An increase in boundary-layer thickness produced a slight decrease in rudder effectiveness. The increase in lift of the combined rudders over that of the upper rudder alone was not proportional at low deflections and was approximately proportional at high deflections to the increase in rudder area. When the balance-chamber cover plates were bowed out, the change in rudder hinge moment with rudder angle was less negative. The variation of the lift coefficient with angle of attack and the variation, at small values of angle of attack, of rudder hinge-noment coefficient with angle of attack was approximately the same for all model configurations tested. The upper rudder used in conjunction with a tab was found to satisfy the Army specifications regarding asymmetric power on a multiengine airplane.

MacLachlan, Robert↗
NASA NTRS1995

Sailplane Glide Performance and Control Using Fixed and Articulating Winglets

An experimental study was conducted to investigate the effects of controllable articulating winglets on glide performance and yawing moments of high performance sailplanes. Testing was conducted in the Texas A&M University 7 x 10 foot Low Speed Wind Tunnel using a full-scale model of the outboard 5.6 feet of a 15 meter class high performance sailplane wing. Different wing tip configurations could be easily mounted to the wing model. A winglet was designed in which the cant and toe angles as well as a rudder on the winglet could be adjusted to a range of positions. Cant angles used in the investigation consisted of 5, 25, and 40 degrees measured from the vertical axis. Toe-out angles ranged from 0 to 22.5 degrees. A rudder on the winglet was used to study the effects of changing the camber of the winglet airfoil on wing performance and wing yawing moments. Rudder deflections consisted of-10, 0, and 10 degrees. Test results for a fixed geometry winglet and a standard wing tip are presented to show the general behavior of winglets on sailplane wings, and the effects of boundary-layer turbulators on the winglets are also presented. By tripping the laminar boundary-layer to turbulent before laminar separation occurs, the wing performance was increased at low Reynolds numbers. The effects on the lift and drag, yawing moment, pitching moment, and wing root bending moment of the model are presented. Oil flows were used on the wing model with the fixed geometry winglet and the standard wing tip to visualize flow directions and areas of boundary layer transition. A cant angle of 25 degrees and a toe-out angle of 2.5 degrees provided an optimal increase in wing performance for the cant and toe angles tested. Maximum performance was obtained when the winglet rudder remained in the neutral position of zero degrees. By varying the cant, toe, and rudder angles from their optimized positions, wing performance decreases. Although the winglet rudder proved to be more effective in increasing the yawing moment compared to varying the cant and toe angles, the amount of increased yawing moment was insignificant when compared to that produced by the vertical tail. A rudder on the winglet was determined to be ineffective for providing additional yaw control.

Colling, James David↗
NASA NTRS1956

Free-Spinning and Recovery Characteristics of a 1/19-Scale Model of the North American T-28C Airplane, TED No. NACA AD 3127

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.

Bowman, James S., Jr.↗
NASA NTRS1950

Free-Spinning-Tunnel Investigation of a 1/30-Scale Model of the Grumman XF1OF-1 Airplane

An investigation has been conducted in the Langley 20-foot free-spinning tunnel on a 1/30 - scale model of the Grumman XFlOF-1 airplane to determine its spin and recovery characteristics. The investigation included erect and inverted spins for both the straight-wing and swept-wing configurations. Tests to determine the optimum size spin-recovery parachutes and the rudder forces required for recovery were also made. The results indicated that in the straight-wing configuration, satisfactory recoveries of the airplane will be obtained from erect and inverted spins by rudder reversal alone. In the swept-wing configuration recoveries will be unsatisfactory from erect spins. Unsweeping the wings during the spin and reversal of the rudder, however, will lead to eventual recovery. The test results also indicated that, if existing small ailerons are made deflectable through large angles, satisfactory recoveries will be obtained from erect spins in the swept-wing configuration by simultaneous movement of the rudder to against the spin and movement of the ailerons to with the spin. Normal-size ailerons deflected through a normal range would also be effective. Satisfactory recoveries by rudder reversal will be obtained from inverted spins in the swept-wing configuration. In the straight-wing configuration a 14.2-foot tail parachute or a 5.0-foot wing-tip parachute opened on the outer wing tip will effect satisfactory recovery of the airplane by parachute action alone; a 30.0-foot tail parachute or a 10.0-foot wing-tip parachute will be required for the swept-wing configuration. The forces required to fully reverse the rudder should be within the capabilities of the pilot.

Berman, Theodore↗
NASA NTRS1987

Spin-tunnel investigation of a 1/15-scale model of an Australian trainer airplane

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.

Bowman, James S., Jr.↗