In 1987, teh DoD and NASA downselected to General Dynamics, McDonnell Douglas, and Rockwell International to proceeed intao a three-year preliminary design phase on the airframe, with Rocketdyne and Pratt& Whitney continuing their propulsion work. By late 1989, the program was stretched to cut costs in the short term.
In 1990, the five conractors began talks on a national contract team to pool resources. In the October 29, 1990 Aviation Week, the details of the down-select were revealed as well as the details of a unique new procurement teaming arrangement.
The X-30A is to be a hypersonic space/aircraft utilizing a wide, lifting body design, with small wings providing the horizontal control surfaces and dual aft vertical stabilizers. The objective is for the control avionics to be of a simple design, providing for a high degree of safety and reduced complexity of the flight control avionics.
The actual design is a blend of the three designs put forth by McDonnell Douglas, General Dynamics, and Rockwell, all of which are particiapating in the development of the prototype. Pratt & Witney Aircraft and Rocketdyne are teaming for the propulsion of the X-30A, with each providing their expertises...P& WA for the air breathing portion of flight, and rocketdyne concentratring on out of atmosphere (as the scramjet moves from turbine to ram, as well as the additional rocket engine envisioned for the craft). There may be between 3 to 5 scramjets. tests have already been performed on engine models of up to Mach 17.
The X-30A will cruise at Mach 2 to 4 to get to the proper altitude, then once engaging the rocket, soar out of the atmosphere and achieving Mach 25.
The first tests of flight regimes will be a short cruise away from Edwards, a gradual turn back towards Edwards, then a brief spurt of acceleration, followed by a long glide back to Edwards. Only the very early flights will place restrictions on the use of the engines, as the X-30A will be quite capable of powered go arounds if necessary. These initial flights will see the X-30A confined to Edwards restricted airspace (R-2508 on Los Angeles sectional VFR maps)
The next regime would begin with a ling cruise across the U.S. toward Kennedy Space Center. If problems occur, the X-30A can land anywheer along hte Souther U.S. Coast, or at Kennedy. If all goes well, then the X-30A will turn at Kennedy, and accelerate to high Mach flying halfway across the U.S., then gliding for the second half before landing at Edwards.
The final max speed runs will occur with a similiar first leg cruising from Edwards to Kennedy. But the acceleration will be longer, and will cross South East to NorthWest, to the Northern Central U.S., and then a short glide, a turn to the SoutheWest, and long glide back to Edwards AFB in California.