Researchers at NASA’s Langley Research Center have designed an electrode-based system for guidance, navigation, and control of aircraft or spacecraft moving at hypersonic speeds in ionizing atmospheres. The system operates based on the principles of magnetohydrodynamics (MHD) and uses energy harvested from the ionized flow occurring during flight at hypersonic speeds to power the electromagnet and generate extremely large Lorentz forces capable of augmenting lift and drag forces to steer and control the craft. The energy harvested can alternatively be stored for later use.
NASA’s MHD patch technology consists of two electrodes positioned a prescribed distance apart on the surface of the TPS of an aircraft or spacecraft and an electromagnetic coil placed directly below the electrodes with the magnetic field protruding out of the surface. During hypersonic flight, the conductive ionizing atmospheric flow over the surface enables current to flow between the two electrodes. This current is harnessed to power the electromagnet which in turn generates strong Lorentz forces that augment lift and drag forces for guidance, navigation, and control of the craft. Alternatively, the current can be used to charge a battery.
Changing the size of the MHD patch (e.g., the length or distance between the electrodes), the strength of the electromagnet, or the direction of the magnetic field enables tuning of generated forces for a given craft design. Multiple MHD patches can be leveraged on a single craft. In-silico evaluation of the MHD patch technology on select aeroshell designs for mock entry into planetary atmospheres has been performed.
A 1m2 MHD patch exerts forces up to 200 kN under simulated Neptune atmosphere entry, significantly increasing the lift/drag (L/D) ratio for the aeroshell investigated. This value is the same order of magnitude as the whole body drag and lift forces computed for the aeroshell, suggesting that generated forces can be used to control a craft.
NASA’s system is simpler than conventional methods for controlling hypersonic craft (e.g., chemical propulsion, shifting flight center of gravity, or trim tabs) and enables new entry, descent, and landing mission architectures.