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Details of the design and development of an airborne data acquisition system for in-flight evaluation of airfoils are presented. The system was designed to be flown aboard a single engine general aviation aircraft and to measure and record airfoil surface pressures, airfoil wake pressures, and aircraft angle of attack and airspeed. Included are descriptions of the instrumentation, calibration and data reduction techniques, illustrations of the raw data and comments on the operational experience gained during the flight evaluation of the GA(W)-2 airfoil.

A brief description of the GA (W) -2 Airfoil Flight Test Evaluation Program is presented. Employing an economical approach to airfoil flight testing, the GA (W) -2 airfoil was “gloved” on the existing wing structure of a Beech Model C23 “Sundowner”. Program objectives, experimental approach, research aircraft modification and instrumentation, data acquisition and processing, flight operations, and preliminary flight test results are described.

A flight test program has been conat the Aeronautical and Astronautical Research Laboratory (AARL) of The Ohio State University to measure performance and acoustic characteristics of four propellers designed for use on single-engine general-aviation airplanes. Three of the propellers were designed to reduce acoustic noise, while the fourth was a standard production propeller used for comparison. The tests show that notacible reduction in near-field noise was achieved at a constant propeller rpm, and that comparable aircraft performance may still be maintained.

Three turbo-propellers were test flown on a Gulfstream Aerospace Commander 695 to measure their acoustic signatures in the near field, as measured by a wing mounted microphone, in the far field as recorded by a ground station in fly-over tests, and in the cabin as monitored by two microphones located in the cabin. Despite differences in airfoils, twist, and planform, the three-bladed propellers exhibited similar pressure-time traces in the near field; therefore, overall sound pressure levels are nearly equal for all propellers at consistent power and air speed. Several hundred acoustic signatures obtained from these propellers during the fly over tests and at pressure altitudes of 10,000 and 20,000 ft for cruise and full power and with both engines operating and with the right engine shut down have been digitized for ready access and are available to acousticians desiring this experimental data.

An analytical method to predict the performance degradation of aircraft with ice accretion is presented. Early research on airfoil icing and the effects of ice on aircraft are reviewed. Data on the performance degradation of airfoils due to ice are presented as they apply to the aircraft performance analysis. A computer code has been written and results are discussed.

Flight tests of a new 13% General Aviation Airfoil - the GA(W)-2 - gloved full span onto the existing wing of a Beech Sundowner have generated chordwise pressure distributions and wake surveys. Section lift, drag and moment coefficients derived from these measurements verify wind tunnel data and theory predicting the performance of this airfoil. The effect of steps, rivets and surface coatings upon the drag of the GA(W)-2 was also evaluated.

The Bellanca Skyrocket II, possessor of five world speed records, is a single engine aircraft with high performance that has been attributed to a laminar flow airfoil and an all composite structure. Utilization of composite materials in the Skyrocket II is unique since this selection was made to increase the aerodynamic efficiency of the aircraft. Flight tests are in progress to measure the overall aircraft drag and the wing section drag for comparison with the predicted performance of the Skyrocket. Initial results show the zero lift drag is indeed low, with CDO = 0.016.