X-15/B-70

It had been proposed that X-15 number 3 would be reworked to install a delta wing and designed to reach Mach 8.

The wing's leading edge would be of columbium, with Rene-41 alloy on the upper and lower surfaces. The rocketplane could have been air-launched from the top of an XB-70, but even when dropped from a subsonic B-52 would be capable of reaching Mach 8. The project was cancelled when X-15 number 3 was destroyed in a crash.

Length: 19.05 m (62.49 ft). Span: 6.80 m (22.30 ft). Mass: 25,000 kg (55,000 lb). Main Engine: XLR-99. Main Engine Thrust: 262.445 kN (59,000 lbf). Main Engine Propellants: Lox/Ammonia. Main Engine Propellants: 20,000 kg (44,000 lb). Main Engine Isp: 276 sec. Spacecraft delta v: 2,400 m/s (7,800 ft/sec). Electrical System: Batteries.

• Jenkins, Dennis R,, Space Shuttle: The History of the National Space Transportation System : The First 100 Missions, Third edition, Voyageur Press, 2001. ISBN: 0963397451. Excellent - the most comprehensive account of the design, development, and flights of the space shuttle.Takes the reader from the maze of designs during the first shuttle competition to future plans. More at amazon.com...