Investigation of the Speed Brakes on the S-67 Aircraft
UNITED TECHNOLOGIES CORP STRATFORD CT SIKORSKY AIRCRAFT DIV
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Flight tests and computer simulations to evaluate speed brakes for a winged helicopter were conducted. The flight test program established the effectiveness of wing-mounted speed brakes for increasing dive angle, deceleration capability, and maneuverability of the Sikorsky S-67. In the configuration tested, six brake surfaces operated together to increase aircraft drag by 155 while reducing wing lift. With these speed brakes, dive angles could be increased from 5 to 7 degrees at 140 knots dependent upon the initial dive angle. At 160 knots, the increase in dive angle varies from 8 to 9 degrees. These increases in aircraft dive angle due to speed brake extension can be further increased by allowing the aircraft to accelerate during the dive. Dive characteristics with and without speed brakes extended were obtained. A dive envelope defined by control and airframe stress limits was established that provided a broad dive envelope of forward speed and collective settings to achieve various dive angles.