Supersonic/Hypersonic Temperature/Drag- Reduction and Vehicle Control

Lines of energy are deposited ahead of supersonic and hypersonic vehicles in order to create a low-density channel, through which a vehicle can travel with dramatically reduced drag. Temperature and pressure are both also reduced on the front surfaces of the vehicle, while density and pressure are increased at the vehicle base. When applied off-center, this technique can be used to control the vehicle, employing the entire body as the control surface and eliminating the need for actuators. Results for drag-reduction, temperature-reduction, and control forces are presented here. K£"ywords: Laser Guided Electric Discharge; Supersonic; Hypersonic; Drag Reduction; Temperature Reduction; Vehicle Control; Shock Wave; Shock Mitigation; Energy Deposition; Gas Heating. PACS: 83.60.Yz; 89.20.Bb; 89.40.Dd; 47.40.-x; 47.40.Hg; 47.40.Ki; 47.40.Nm; 47.40.Rs; 47.60.Dx; 47.85.Gj ; 47.85.L-; 47.85.lb; 51.50.+v; 52.25.Jm; 52 .50.Jm; 52.38.Hb. HYPERSONIC DRAG REDUCTION AND CONTROL Applications and Background Hypersonic and supersonic vehicles/missiles generate shock waves, which are accompanied by a host of technical challenges. These include increased drag, sonic boom, and destmctively high temperatures and pressures on their airframe and components. "Suddenly heating" an extended path of air, ahead of the shock wave and along the vehicle's velocity vector, results in rapid expansion of the heated air. This creates a long, hot, low-density core, into which the vehicle's shock wave expands, fo llowed by the vehicle itself (Figure lc). This deposition occurs in pulsed fashion, being repeated when each core has been traversed and the ambient air is once again encountered by the vehicle. Strategically heating extended regions of gas ahead of the vehicle can therefore mitigate the shock wave, as well as its deleterious effects. Also, since the vehicle will preferentially fly along the low-density channel, (e.g. be partially steered by it), adjusting the direction/position of the hot core formation can be utilized as a method of control (Figure 2).