| Popis: |
For the past several years, Lockheed Martin and the United States Air Force Academy have been investigating the drag reduction potential for different variants of the C-130. This investigation was the fourth and final phase of the effort to maximize the drag reduction potential through aft body modifications to the C-130. This phase focused on two objectives involving a beavertail strake modification on the aft body: investigate the drag reduction potential through a representative range of C-130 deck angles, and analyze and define the longitudinal, lateral, and directional static stability implications of the beavertail strake modification. A significant drag reduction potential of 12 drag counts was found for a deck angle of 1.5 degrees which correlated well with results from previous phases. An increase in drag was found at deck angles greater than 4 degrees, but this should not be a concern since a typical C-130 mission spends very little time at these deck angles. The static stability evaluation showed that the addition of beavertail strakes generally increases both longitudinal and directional stability while lateral stability is relatively unchanged. Trim angle changes were identified which will require additional trailing edge up elevator deflection. The addition of C-130 aft body strakes was expected to increase mission radius by up to 18 NM, or loiter time by up to 6 minutes, or result in an overall fuel savings of up to 506 pounds per 6 hour mission. This was projected to an overall fuel savings of approximately 35.5 million pounds per year for the C-130 fleet. It is recommended that the flow characteristics that effect directional stability at a deck angle of 3.7 degrees be investigated since a decrease in directional stability was found at this one condition. This effort was funded by Lockheed Martin Corporation (Marietta). |
