It is an enlarged version of their Velocity SE canard pusher design.

The now-defunct Rocket Racing League utilized a highly modified Velocity XL FG airframe and an Armadillo Aerospace 2,500 pound thrust liquid oxygen (LOX) and ethanol rocket engine in both its Mark-II X-Racer and Mark-III X-Racer demonstration vehicles.

The Mark-II utilized a standard fixed-gear Velocity XL airframe, modified for rocket propulsion.

The Mark-III airframe was more extensively customized during manufacture, explicitly for rocket racing, with a canopy top, center seat and control stick and other enhancements, in addition to the rocket propulsion added to the Mark-II.

[9] Data from Jane's All the World's Aircraft 2013/14[3]General characteristics Performance