By Rob Coppinger in London

Launching small payloads into space using an airborne electromagnetic (EM) rail gun fitted to a Lockheed Martin C-5B transport is the focus of a three-year, $750,000 study funded by the US Air Force Office of Scientific Research.

The C-5B would fly to 50,000ft (15,250m) and fire the payload, which would be between 1kg (2.5lb) and 10kg in mass, into space. A possible alternative launch aircraft is the Airbus A380 Freighter.

Because a velocity of 7km/s (4.35 miles/s) is needed to reach orbit, the payload would experience high thermal loads if fired through the lower atmosphere. The solution is to fly the rail-gun launcher system to 50,000ft, where the air density is low enough to reduce the thermal loads to a manageable level.

“We are looking at the fundamentals of how we can launch payloads to these velocities. It’s an aerothermal problem we’re trying to solve. There is no hardware as it’s a paper study,” says Ian McNab, electromagnetic systems director for the University of Texas at Austin’s Institute for Advanced Technology.

McNab also cites European research into EM launches involving EADS and German Aerospace centre DLR, a project that aims to fire a payload at 2km/s to 125km (80 miles) altitude.

One potential spin-off application for McNab’s technology is a tactical air-to-air or air-to-ground gunship capable of firing lethal projectiles at very high velocities, with the benefit of a low muzzle blast because the rounds are not explosive.

Source: Flight International