X-15A-2 Credit: NASA. 17,207 bytes. 500 x 178 pixels.

A crashed X-15 no. 2 was rebuilt to attain even higher speeds. The body frame was stretched, two drop tanks were added, increasing fuel load by 75%. An ablative heat shield was applied for the high speeds that could be attained. The X-15A-2 reached the highest speeds and altitudes of any manned spaceplane until the space shuttle entered service.

The X-15A-2, modified from the number two aircraft and delivered to NASA in February 1964, included among other new features, a 28-in. fuselage extension to carry liquid hydrogen for a supersonic combustion ramjet that was flown (as a dummy) but never tested. It also had external tanks for liquid ammonia and liquid oxygen. These tanks provided roughly 60 seconds of additional engine burn and were used on the aircraft's Mach 6.7 flight. While adding to the speed the X-15 did achieve, the tanks also increased the aircraft's weight to almost 57,000 lb and added significantly to the drag experienced by the aircraft in flight.

The X-15A-2, modified from the number two aircraft, included among other new features, a 28-in. fuselage extension to carry liquid hydrogen for a supersonic combustion ramjet that was flown (as a dummy) but never tested. It also had external tanks for liquid ammonia and liquid oxygen. These tanks provided roughly 60 seconds of additional engine burn and were used on the aircraft's Mach 6.7 flight.

Maximum Speed - 4994 kph. Maximum Altitude - 25390 m. First flight of X-15 No. 2 in X-15A-2 configuration, but without drop tanks.

---

X-15 ablative coat - X-15A-2 ablative coating Credit: NASA. 15,418 bytes. 464 x 274 pixels.

---

Maximum Speed - 5699 kph. Maximum Altitude - 29809 m.

Maximum Speed - 4970 kph. Maximum Altitude - 26579 m.

Maximum Speed - 5649 kph. Maximum Altitude - 28986 m. Right main landing gear extended at Mach 4.1; normal landing.

Maximum Speed - 5266 kph. Maximum Altitude - 28224 m. First star tracker checkout.

Maximum Speed - 5697 kph. Maximum Altitude - 31120 m.

---

X15 Delta 11,604 bytes. 524 x 288 pixels.

---

Maximum Speed - 5887 kph. Maximum Altitude - 64800 m. Star tracker mission to photograph Gamma Cassiopeia.

Maximum Speed - 5796 kph. Maximum Altitude - 63612 m.

Maximum Speed - 5744 kph. Maximum Altitude - 73091 m.

First flight with empty external tanks. Ammonia tank recovered; Lox tank destroyed. Maximum Speed - 2414 kph. Maximum Altitude - 21520 m.

Maximum Speed - 5936 kph. Maximum Altitude - 30170 m.

First flight with fueled external tanks. Engine shutdown at 34.6 seconds due to fuel flow anomalies. Maximum Speed - 1646 kph. Maximum Altitude - 13720 m.

Maximum Speed - 5741 kph. Maximum Altitude - 58610 m.

Maximum Speed - 5535 kph. Maximum Altitude - 75890 m. UV photos of stars in Auriga.

Maximum Speed - 5586 kph. Maximum Altitude - 70440 m.

Maximum Speed - 5701 kph. Maximum Altitude - 30540 m.

Unofficial world's speed record. Maximum Speed - 6838 kph. Maximum Altitude - 30140 m.

Maximum Speed - 5138 kph. Maximum Altitude - 29750 m. Check out of stability and control with ramjet pod.

First test with full ablative coating, ramjet pod. Maximum Speed - 5419 kph. Maximum Altitude - 27740 m.

Unofficial world speed record (full ablative coating, dummy ramjet, mechanical eyelid). Maximum Speed - 7273 kph. Maximum Altitude - 31120 m.

• 38 - Guenther, Ben, Miller, Jay, and Panopalis, Terry,, North American X-15/X-15A-2, Aerofax, Arlington, Texas, 1985.
• 49 - Miller, Ron, The Dream Machines, Krieger, Malabar, Florida, 1993.
• 97 - Zhelyez x-plane book, .
• 459 - NASA Dryden Flight Research Center Web Site, . HTML when accessed: http://www.dfrc.nasa.gov/