Martin Marietta X-24

The Martin Marietta X-24 is an American experimental aircraft developed from a joint United States Air Force–NASA program named PILOT (1963–1975). It was designed and built to test lifting body concepts, experimenting with the concept of unpowered reentry and landing, later used by the Space Shuttle. Originally built as the X-24A, the aircraft was later rebuilt as the X-24B.

The X-24 was drop launched from a modified B-52 Stratofortress at high altitudes before igniting its rocket engine; after expending its rocket fuel, the pilot would glide the X-24 to an unpowered landing.

Design and development

thumb|right|Martin X-24A

The X-24 was one of a group of lifting bodies flown by the NASA Flight Research Center (now Armstrong Flight Research Center) in a joint program with the U.S. Air Force at Edwards Air Force Base in California from 1963 to 1975. The lifting bodies were used to demonstrate the ability of pilots to maneuver and safely land wingless vehicles designed to fly back to Earth from space and be landed like an airplane at a predetermined site.

Lifting bodies’ aerodynamic lift, essential to flight in the atmosphere, was obtained from their shape. The addition of fins and control surfaces allowed the pilots to stabilize and control the vehicles and regulate their flight paths.

The X-24 (Model SV-5P) was built by Martin Marietta and flown from Edwards. The X-24A was the fourth lifting body design to fly; it followed the NASA M2-F1 in 1964, the Northrop HL-10 in (1966), the Northrop M2-F2 in 1966 and preceded the Northrop M2-F3 (1970).

The X-24A was a fat, short teardrop shape with three fins for control—the center fin vertical and the left and right fins canted slightly outward. It made its first, unpowered, glide flight on April 17, 1969 with Air Force Maj. Jerauld R. Gentry at the controls. Gentry also piloted its first powered flight on March 19, 1970. The craft was taken to around 45,000 feet (13.7 km) by a modified B-52, drop-launched, then either glided down or used its rocket engine to ascend to higher altitudes before gliding down. The X-24A was flown 28 times at speeds up to 1,036 mph (1,667 km/h) and altitudes up to 71,400 feet (21.8 km).

X-24B

The X-24B's design evolved from a family of potential reentry shapes, each with higher lift-to-drag ratios, proposed by the Air Force Flight Dynamics Laboratory. To reduce the costs of constructing a research vehicle, the Air Force returned the X-24A to the Martin Marietta Corporation—as Martin Aircraft Company became after a merger—for modifications that converted its bulbous shape into one resembling a "flying flatiron", i.e., rounded top, flat bottom, and a double delta planform that ended in a pointed nose.

John A. Manke was the first to fly the X-24B, a glide flight on 1 August 1973. He was also the pilot on the first powered mission 15 November 1973.

X-24C

A variety of "X-24C" proposals were floated between 1972 and 1978. Perhaps the most notable was a Lockheed Skunk Works design, the L-301, which was to use scramjets to reach a top speed of Mach 8.

SV-5J

thumb|SV-5J displayed as the X-24A at the [[National Museum of the United States Air Force]]

After learning about a remark by Chuck Yeager that he would like to have some jet-powered lifting bodies for training purposes, Martin designed and built, on its own initiative, two examples of the SV-5J.

|prime units?=kts

<!--

General characteristics

-->

|crew=1

|length ft=37

|length in=6

|length note=

|span ft=19

|span in=2

|span note=

|height ft=10

|height in=4

|height note=

|wing area sqft=330

|wing area note=

|aspect ratio=

|airfoil=

|empty weight lb=7800

|empty weight note=zero propellant weight

|gross weight lb=

|gross weight note=

|max takeoff weight lb=13800

|max takeoff weight note=

|fuel capacity= total propellant weight (ethyl-alcohol/water fuel and LOX oxidiser)

|more general=

<!--

Powerplant

-->

|eng1 number=1

|eng1 name= Reaction Motors XLR11-RM-13 (Thiokol)

|eng1 type=4-chamber liquid-fuelled rocket engine

|eng1 lbf=8000

|eng1 note=

|eng2 number=2

|eng2 name= Bell LLRV landing rockets

|eng2 type=solid-fuelled rocket engine

|eng2 lbf=400–500

|eng2 note=(optional)

<!--

Performance

-->

|max speed kts=868

|max speed note=at

|max speed mach=1.52

|cruise speed kts=

|cruise speed note=

|stall speed kts=

|stall speed note=

|never exceed speed kts=

|never exceed speed note=

|range nmi=39

|range note=

|combat range nmi=

|combat range note=

|ferry range nmi=

|ferry range note=

|endurance=

|ceiling ft=74130

|ceiling note=

|g limits=

|roll rate=

|glide ratio=

|climb rate ftmin=

|climb rate note=

|time to altitude=

|sink rate ftmin=

|sink rate note=

|lift to drag=

|wing loading lb/sqft=42

|wing loading note=

|fuel consumption lb/mi=

|thrust/weight=0.71

|more performance=

|avionics=

References

Notes

Bibliography

Miller, Jay. The X-Planes: X-1 to X-45. Hinckley, UK: Midland, 2001.
Reed, R. Dale with Darlene Lister. Wingless Flight: The Lifting Body Story. Lexington, KY: University Press of Kentucky, 2002. .
Rose, Bill, 2008. Secret Projects: Military Space Technology. Hinckley, England: Midland Publishing.
Winchester, Jim. "Martin-Marietta X-24." X-Planes and Prototypes. London: Amber Books Ltd., 2005. .

External links

NASA Dryden X-24 Photo Collection
X-24A and X-24B at Encyclopedia Astronautica

Design and development

X-24B

X-24C

SV-5J

See also

References

Notes

Bibliography

External links