A few illustrations from a 2010 NASA presentation showing the two stage to orbit “RALV-B” (Reusable Airbreathing Launch Vehicle – iteration B). This is essentiallythe latest evolution of the X-30 NASP concept. While NASP died years ago, the basic concept – and even the basic design – survived on the back burner of aerospace studies. Note that the views show something that the NASP artwork almost never did… rocket engines on the airbreather.
The X-30 NASP would have required rocket engines to attain orbit. Even if the scramjet engine would have been able to propell the vehicle to Mach 25 – which seems spectacularly unlikely – it would have only been able to do so within the atmosphere. Thus a pure airbreather might pop out of the atmosphere, but without rockets to circularize and expand the orbit, it would just drop right back down again. But all the publicity artwork showed rocket-less spaceplanes. But if you know where to look, you can find drawings and diagrams of NASP competitors, and NASP derivatives, with rocket engines. By the end of the NASP program, designers seemed to have settled on a linear aerospike engine above the flat tail. Whether this had any influence on the X-33, I can’t say, but the aerospike engines did tend to resemble those of the X-33.
The RALV-B shown here uses a bank of conventional bell-nozzle rocket engines for final pull-up before second stage separation. Turbine based combined cycle engines are used for acceleration and climb . It is to be an unmanned vehicle capable of launching 20,000 pounds of payload to a 28.5 degree, 100 nautical mile circular orbit. Payload bay is 12 feet in diameter, 30 feet long. Dimensions for the vehicles are not given, but can be estimated from the payload bay.


