Flight Testing of a Variable Sweep Wing Aircraft


Book Description

In the late 1940's, it appeared that the capabilities of the catapult and arresting gear on existing carriers were becoming inadequate for the higher airplane weights and speeds which accompanied the introduction of turbojet-powered, swept-wing carrier-based aircraft. The U.S. Navy's approach to the problem encompassed two developments, the angled carrier deck in combination with the steam catapult and the Grumman XF10F-1 fighter with variable geometry wings for reduction of take-off and landing speeds. Although the XF10F-1 did not go into production because of certain other unsatisfactory design innovations, the wing, which could be swept in the air from 13 1/2 to 42 1/2 degrees, was shown to be operationally feasible and structurally practical. It also gave the expected reduction in aircraft take-off and landing speeds which could have offset carrier modifications. As aircraft size and performance continued to increase during the last decade, the problem of catapult capability versus carrier aircraft weight and speed again became apparent. This time, the TFX variable geometry wing aircraft was considered a more practical solution than further increasing the carrier catapult and arresting capabilities. (Author).
















Flight Testing of Fixed Wing Aircraft


Book Description

Annotation The measurement of performance during an airplane's flight, testing is one of the more important tasks to be accomplished during its development as it impacts on both the airplane's safety and its marketability. This book discusses performance for both propeller-driven and jet aircraft.




Application of a Performance Modeling Technique to an Airplane with Variable Sweep Wings


Book Description

A performance modeling concept previously applied to an F-104F G and a YF-12C airplane was applied to an F-111A airplane. This application extended the concept to an airplane with variable sweep wings. The performance model adequately matched flight test data for maneuvers flown at different wing sweep angles at maximum afterburning and intermediate power settings. For maneuvers flown at less than intermediate power, including dynamic maneuvers, the performance model was not validated because the method used to correlate model and in-flight power setting was not adequate. Individual dynamic maneuvers were matched sucessfully by using adjustments unique to each maneuver. Redin, P. C. Armstrong Flight Research Center NASA-TP-1855, H-1131 RTOP 505-43-24...




Transonic Aerodynamic and Aeroelastic Characteristics of a Variable Sweep Wing


Book Description

The flow over the B-1 wing is studied computationally, including the aeroelastic response of the wing. Computed results are compared with results from wind tunnel and flight tests for both low-sweep and high-sweep cases, at 25.0 deg and 67.5 deg; respectively, for selected transonic Mach numbers. The aerodynamic and aeroelastic computations are made by using the transonic unsteady code ATRAN3S. Steady aerodynamic computations compare well with wind tunnel results for the 25.0 deg sweep case and also for small angles of attack at the 67.5 deg sweep case. The aeroelastic response results show that the wing is stable at the low sweep angle for the calculation at the Mach number at which there is a shock wave. In the higher sweep case, for the higher angle of attack at which oscillations were observed in the flight and wind tunnel tests, the calculations do not show any shock waves. Their absence lends support to the hypothesis that the observed oscillations are due to the presence of leading edge separation vortices and are not due to shock wave motion as was previously proposed.







Flutter Clearance of the F-14a Variable-Sweep Transition Flight Experiment Airplane, Phase 2


Book Description

An F-14A aircraft was modified for use as the test-bed aircraft for the variable-sweep transition flight experiment (VSTFE) program. The VSTFE program was a laminar flow research program designed to measure the effects of wing sweep on laminar flow. The airplane was modified by adding an upper surface foam and fiberglass glove to the right wing. An existing left wing glove had been added for the previous phase of the program. Ground vibration and flight flutter testing were accomplished to verify the absence of aeroelastic instabilities within a flight envelope of Mach 0.9 or 450 knots, calibrated airspeed, whichever was less. Flight test data indicated satisfactory damping levels and trends for the elastic structural modes of the airplane. Ground vibration test data are presented along with in-flight frequency and damping estimates, time histories and power spectral densities of in-flight sensors, and pressure distribution data. Freudinger, Lawrence C. and Kehoe, Michael W. Armstrong Flight Research Center RTOP 505-60-31...