Influence of transport aircraft wake vortex on parachute and calculation method of formation airdrop spacing

The pursuit of high efficiency should take into account the risk that the transport aircraft wake vortex poses to the parachute, even though the transport aircraft formation airdrop can carry more equipment and commodities to the designated location in the shortest amount of time. In order to solve this problem, the research on the influence of transport aircraft wake vortex on parachute and the calculation method of formation airdrop spacing is proposed. Firstly, the risk assessment model of the wake vortex encountered during the airdrop parachute landing process was established. Secondly, the danger of the transport aircraft formation airdrop was calculated and analyzed. Thirdly, the safety transport aircraft formation airdrop spacing was calculated and analyzed. The results show that the time of the single file formation airdrop in the wake vortex danger area is 2.0 times that of the herringbone formation airdrop. With the increase of the airdrop altitude, the influence of the four factors of the transport aircraft's flight speed, the radius of the parachute canopy, the time to open the parachute, and the temperature deviation on the time of the airdrop parachute during landing in the wake vortex danger area increases first and then decreases. Three C-17 transport aircraft were airdropped in a herringbone formation when the airdrop altitude changed from 100 meters to 1000 meters. If the left and right spacing is 100 meters, the safe front and back spacing gradually increases with the increase of the airdrop altitude, starting from 500 meters, the airdrop altitude increases by 20 meters for every 100 meters. When the airdrop altitude shifts from 100 to 200 meters, the safe left and right spacing is 100 meters; when the airdrop altitude shifts from 300 to 1 000 meters, the safe left and right spacing is 110 meters if the front and rear spacing is 3 500 meters.