Parametric Study of the Towline Shape of an Aircraft Decoy

Some of today's aircraft use decoys as a defense against enemy weapons. The decoy is towed behind the aircraft with the intention of attracting the weapon propagator by deception, trying to mislead the weapon into detecting it instead of the aircraft. An aircraft deploys a decoy via a towline extending out behind and below the aircraft. However, during some maneuvers, the towline moves up into the jet exhaust plume of the aircraft. The high temperatures of the exhaust can cause damage to the towline cable, ranging from disrupting data flow between the decoy and aircraft to severing the towline altogether. This research modeled the system to determine the towline shape and position relative to the aircraft under steady state conditions. Non-dimensional parameters were utilized in order to investigate what parameter groups effect the motion of the towline, reducing the steady state solution space from 7 parameters to 2 parameters. The effect of both parameter groups in determining the shape of the towline was studied, and recommendations for preventing the towline from entering the jet exhaust during straight and level flight were made.