Lockheed X-7

X-7
300px
Role	Experimental aircraft
Manufacturer	Lockheed Corporation
First flight	April 26, 1951
Retired	1960
Primary user	United States Air Force
Developed into	AQM-60 Kingfisher

The Lockheed X-7 (dubbed the "Flying Stove Pipe") was an American unmanned test bed of the 1950s for ramjet engines and missile guidance technology. It was the basis for the later Lockheed AQM-60 Kingfisher, a system used to test American air defenses against nuclear missile attack.

The aircraft is one of the lesser known designs by Kelly Johnson, who went on to become the creator of the SR-71 family of aircraft.

Design and development

X-7 being dropped

The X-7 was carried aloft by a B-29 or B-50 Superfortress carrier aircraft. A booster ignited after launch and propelled the vehicle to a speed of 1,000 mph (1,625 km/h). The booster was then jettisoned, and the underslung ramjet took over from that point. The X-7 eventually returned to Earth, its descent slowed by parachute. A maximum speed of 2,881 mph (4640 km/h / Mach 4.31) was attained, setting a record for fastest air-breathing aircraft at the time. A total of 130 X-7 flights were conducted from April 1951 to July 1960.

The X-7 was unique in that it was constructed of steel, as opposed to the titanium used on later ramjets such as the more well known SR-71, and its predecessors, the A-12 and YF-10. The X-2 test aircraft preceded the X-7 by having Stainless steel wings, but its fuselage was composed of Nickel alloy. Steel was not widely used in aircraft until the later Mig-25 Foxbat.

The X-7 was also used to test HEF-2 and Hi Cal-3 zip fuel, which has a superior heating value of 26,500 Btu/lb. compared to hydrocarbon fuel with 18,400 Btu/lb.

Specifications (X-7A-1)

General characteristics

• Crew: None
• Length: 32 ft 9 in (9.98 m)
• Wingspan: 12 ft (3.66 m)
• Height: 7 ft (2.1 m)
• Loaded weight: 8,000 lb (3,600 kg)
• Powerplant:
  • 1 × Alleghany Ballistics Laboratories X202-C3 solid-fuel rocket, 105,000 lbf (467 kN)
  • 1 × various Marquardt MA20 ramjets under test, ()

Performance

• Maximum speed: Mach 4.31 (2,881 mph, 4,640 km/h)
• Service ceiling: 106,000 ft (32,317 m)

See also

Related development

• Q-5 Kingfisher

Aircraft of comparable role, configuration and era

• Bomarc

External links

• Q-5/AQM-60
• "Ramjet test missile takes off on supersonic flight." Popular Science, pp. 142–143.