# Lockheed L-2000
The Lockheed L-2000 was [Lockheed Corporation](https://www.edgepedia.org/lockheed-corporation)'s design for a supersonic transport (SST) airliner, submitted in a United States government-funded competition in the 1960s to build the country's first supersonic passenger aircraft. It was a fixed-wing double-delta design cruising at Mach 2.7, and it lost the final round of the competition to Boeing's variable-geometry Model 2707 on December 31, 1966.[1](https://www.globalsecurity.org/military/systems/aircraft/l-2000.htm) • [2](https://www.historylink.org/File/2687)
| Key fact | Detail |
|---|---|
| Role | Lockheed's entry in the US Supersonic Transport competition run by the Federal Aviation Administration[1](https://www.globalsecurity.org/military/systems/aircraft/l-2000.htm) |
| Configuration | Fixed-wing double delta, four engines in individual ducts under the rear of the wings, drooping nose for landing visibility[1](https://www.globalsecurity.org/military/systems/aircraft/l-2000.htm) |
| Performance goal | Mach 2.7 cruise, range of at least 4,000 nautical miles in the initial concept[1](https://www.globalsecurity.org/military/systems/aircraft/l-2000.htm) |
| Final versions | L-2000-7A: 273 ft long, 258 international or 273 all-coach seats; stretched L-2000-7B: 293 ft, about 250 passengers[3](https://cap-avenir-concorde.fr/interavia-decembre-1966-le-sst-a-double-delta-de-lockheed/) • [4](https://migflug.com/afterburner/lockheed-l-2000-american-sst-that-lost-to-boeing-2707/) |
| Engines | Four General Electric GE4/J5 or Pratt & Whitney JTF17A turbojets[1](https://www.globalsecurity.org/military/systems/aircraft/l-2000.htm) |
| Competition result | Lost to the Boeing 2707-200 on December 31, 1966, despite being judged simpler to produce and less risky[2](https://www.historylink.org/File/2687) • [5](https://airandspace.si.edu/collection-objects/model-wind-tunnel-lockheed-sst/nasm_A19690228000) |
| Fate | Never built; the full-scale mockup was used for evacuation tests and then scrapped[6](https://www.inventionandtech.com/content/going-nowhere-fast-0) |
## Origins in the American SST program
President [John F. Kennedy](https://www.edgepedia.org/john-f-kennedy) committed the United States to developing a supersonic transport in a June 5, 1963 speech at the [United States Air Force Academy](https://www.edgepedia.org/united-states-air-force-academy), pledging to develop "at the earliest practical date the prototype of a commercially successful supersonic transport superior to that being built in any other country in the world."[1](https://www.globalsecurity.org/military/systems/aircraft/l-2000.htm) Design proposals were received in January 1964 from three airframe manufacturers, Lockheed, Boeing, and [North American Aviation](https://www.edgepedia.org/north-american-aviation), and three engine companies, Pratt & Whitney, Curtiss-Wright, and General Electric.[1](https://www.globalsecurity.org/military/systems/aircraft/l-2000.htm) In May 1964 contracts were awarded to Boeing and Lockheed for further airframe studies and to General Electric and Pratt & Whitney for engine work.[1](https://www.globalsecurity.org/military/systems/aircraft/l-2000.htm)
The initial Lockheed concept was a 400,000-pound titanium airplane carrying 125 to 160 passengers at Mach 2.7 over a range of at least 4,000 nautical miles.[1](https://www.globalsecurity.org/military/systems/aircraft/l-2000.htm) Lockheed's first competition entry, the Model CL-823, was a fixed-wing double-delta that the company considered a simpler, lighter airplane than Boeing's variable-sweep design; NASA later judged both companies' performances substantially short of the design goals.[7](https://ntrs.nasa.gov/api/citations/20060005004/downloads/20060005004.pdf)
## Design evolution
**From canards to double delta.** A supersonic transport tends to pitch down as it accelerates from subsonic to supersonic flight. Early Lockheed layouts needed canards, small wings near the nose, to counteract this, but the double-delta configuration made them unnecessary: the forward delta begins generating lift supersonically, and at low speeds vortices from the leading edge increase lift, allowing many flaps and slats to be eliminated.[1](https://www.globalsecurity.org/military/systems/aircraft/l-2000.htm) In landing, the double delta produces a ground-cushion effect that permits lower landing speeds.[1](https://www.globalsecurity.org/military/systems/aircraft/l-2000.htm)
**The L-2000-2.** When the FAA awarded the airframe and engine contracts on January 1, 1965, it also required Lockheed and Boeing to evaluate a NASA design called SCAT 15F, intended to address range, payload, and sonic boom concerns.[8](https://declassification.blogs.archives.gov/2017/07/28/what-happened-to-the-american-sst/) The revised L-2000-2 reflected extensive wing changes: maximum thickness reduced to 2.3 percent of the chord, sharper leading edges, sweep angles changed from 80/60 degrees to 85/62 degrees, and substantial twist and camber added to the forward delta. Wing-body fairings under the fuselage allowed a more normally shaped nose, which reduced overall length to 214 ft (65.2 m) while wing area grew to 9,026 ft² (838.5 m²), and the overall lift-to-drag ratio rose from 7.25 to 7.94.[9](https://www.secretprojects.co.uk/threads/us-supersonic-transport-sst-program-1960-1971.483/page-17)
**The L-2000-7.** The 1966 final design took the form of two versions. The L-2000-7A was 273 ft (83.2 m) long with a cabin arrangement of 258 seats in an international layout or 273 seats all-coach, a very slender fuselage whose nose could be lowered to improve pilot visibility at low speeds and landing, and four turbojets mounted under the double-delta wing.[3](https://cap-avenir-concorde.fr/interavia-decembre-1966-le-sst-a-double-delta-de-lockheed/) With an identical maximum takeoff weight of 267 tons, the -7A was credited with 230 passengers in two classes over 4,000 miles, and the stretched -7B, at 293 ft (89.4 m), about 250 passengers over 3,000 to 3,500 miles.[1](https://www.globalsecurity.org/military/systems/aircraft/l-2000.htm) • [4](https://migflug.com/afterburner/lockheed-l-2000-american-sst-that-lost-to-boeing-2707/) The -7B had a maximum weight of 590,000 lb.[4](https://migflug.com/afterburner/lockheed-l-2000-american-sst-that-lost-to-boeing-2707/) Lockheed also planned an alternate version for domestic service while keeping the basic L-2000-7 international design with constant fuselage cross-section and five-abreast seating.[10](https://archive.aviationweek.com/issue/19660905) Lockheed marketed the design to airlines such as Swissair and claimed the L-2000 would reach break-even at a 30 percent load factor.[11](https://airport.consulting/l2000/)
## The 1966 decision
Both companies built full-scale mockups for the final round. A mockup model of the L-2000 was completed in mid-1966 with a replica flight deck and fully furnished passenger accommodation, and the full-scale L-2000-7 mockup was presented in [Burbank, California](https://www.edgepedia.org/burbank-california) in June 1966.[1](https://www.globalsecurity.org/military/systems/aircraft/l-2000.htm) Jane's All the World's Aircraft for 1966 called it "the most complete engineering mock-up of a future airliner ever built."[12](https://pocketmags.com/airliner-world-magazine/november-2023/articles/more-than-a-mock-up-revisiting-sst)
On December 31, 1966, the federal government selected Boeing, with its radical variable-geometry "swing-wing" 2707-200 design, over Lockheed for the SST airframe, and [General Electric](https://www.edgepedia.org/general-electric) over [Pratt & Whitney](https://www.edgepedia.org/pratt-and-whitney) for the engines.[2](https://www.historylink.org/File/2687) • [13](https://www.nasa.gov/wp-content/uploads/2023/04/1966.pdf?emrc=8ffcff) The Smithsonian's National Air and Space Museum notes that the L-2000 was judged simpler to produce and less risky, but it lost anyway.[5](https://airandspace.si.edu/collection-objects/model-wind-tunnel-lockheed-sst/nasm_A19690228000) A 1/60-scale steel wind-tunnel model of the design, gifted by Lockheed-California Co., remains in the museum's collection.[5](https://airandspace.si.edu/collection-objects/model-wind-tunnel-lockheed-sst/nasm_A19690228000)
## Aftermath
Lockheed's mockup was reclaimed by the FAA, disassembled, and taken to the agency's research center in [Oklahoma City](https://www.edgepedia.org/oklahoma-city), where its fuselage was used for passenger evacuation tests in 1967; when it outlived its usefulness it was left outdoors, ruined by weather, and sold for scrap.[6](https://www.inventionandtech.com/content/going-nowhere-fast-0) • [14](https://www.secretprojects.co.uk/threads/us-supersonic-transport-sst-program-1960-1971.483/page-22)
Boeing's winning design did not survive in its original form. Weight estimates for the swing-wing grew from 500,000 pounds in 1966 to 675,000 pounds in 1967, and in the fall of 1968 Boeing replaced the swing wings with fixed wings based on a NASA design that, to reporters who saw the later mockup, looked much like Lockheed's rejected double-delta wings.[6](https://www.inventionandtech.com/content/going-nowhere-fast-0) The Museum of Flight archives describe the fixed-wing 2707-300 as "little different from the Lockheed L-2000 that had lost to the 2707-200 in 1966."[15](https://archives.museumofflight.org/subjects/36?filter_fields%5B%5D=published_agents&filter_values%5B%5D=Ellis%2C+Steve)
The American SST program itself was canceled in May 1971, when the Senate ended funding by a 58 to 37 vote amid environmental objections over sonic boom and takeoff noise and doubts about the economics.[6](https://www.inventionandtech.com/content/going-nowhere-fast-0) Lockheed canceled its L-2000 development the same year.[16](https://www.militaryfactory.com/aircraft/detail.php?aircraft_id=1953) No American supersonic transport was ever built; Concorde, which used a related double-delta wing, provided commercial supersonic service from 1976 to 2003.[2](https://www.historylink.org/File/2687) • [17](https://www.nasa.gov/centers-and-facilities/armstrong/nasas-quesst-reassessing-a-50-year-supersonic-speed-limit/)
## References
1. [L-2000 Supersonic Transport, GlobalSecurity.org](https://www.globalsecurity.org/military/systems/aircraft/l-2000.htm)
2. [Boeing wins contract to develop prototype supersonic transport (SST) on December 31, 1966, HistoryLink.org Essay 2687](https://www.historylink.org/File/2687)
3. [INTERAVIA, Décembre 1966: Le SST à double delta de Lockheed, CAP Avenir Concorde](https://cap-avenir-concorde.fr/interavia-decembre-1966-le-sst-a-double-delta-de-lockheed/)
4. [Lockheed L-2000: The American SST That Lost to the Boeing 2707, MiGFlug](https://migflug.com/afterburner/lockheed-l-2000-american-sst-that-lost-to-boeing-2707/)
5. [Model, Wind Tunnel, Lockheed SST, National Air and Space Museum](https://airandspace.si.edu/collection-objects/model-wind-tunnel-lockheed-sst/nasm_A19690228000)
6. [Going Nowhere Fast, Invention & Technology Magazine](https://www.inventionandtech.com/content/going-nowhere-fast-0)
7. [Supersonic Civil Aircraft: The Need for Speed, NASA SP-472](https://ntrs.nasa.gov/api/citations/20060005004/downloads/20060005004.pdf)
8. [What Happened to the American SST?, National Declassification Center blog](https://declassification.blogs.archives.gov/2017/07/28/what-happened-to-the-american-sst/)
9. [US Supersonic Transport (SST) Program 1960–1971, Secret Projects Forum](https://www.secretprojects.co.uk/threads/us-supersonic-transport-sst-program-1960-1971.483/page-17)
10. [Aviation Week & Space Technology, September 5, 1966](https://archive.aviationweek.com/issue/19660905)
11. [The other Supersonic – Lockheed L2000, Jean-Christophe Dick](https://airport.consulting/l2000/)
12. [More Than a Mock-Up: Revisiting SST, Airliner World, November 2023](https://pocketmags.com/airliner-world-magazine/november-2023/articles/more-than-a-mock-up-revisiting-sst)
13. [Astronautics and Aeronautics, 1966, NASA](https://www.nasa.gov/wp-content/uploads/2023/04/1966.pdf?emrc=8ffcff)
14. [US Supersonic Transport (SST) Program 1960–1971, page 22, Secret Projects Forum](https://www.secretprojects.co.uk/threads/us-supersonic-transport-sst-program-1960-1971.483/page-22)
15. [Boeing Model 2707 SST, Museum of Flight Archives](https://archives.museumofflight.org/subjects/36?filter_fields%5B%5D=published_agents&filter_values%5B%5D=Ellis%2C+Steve)
16. [Boeing Model 2707 (SST) Supersonic Transport Airliner Proposal, Military Factory](https://www.militaryfactory.com/aircraft/detail.php?aircraft_id=1953)
17. [NASA's Quesst: Reassessing a 50-Year Supersonic Speed Limit, NASA](https://www.nasa.gov/centers-and-facilities/armstrong/nasas-quesst-reassessing-a-50-year-supersonic-speed-limit/)
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*Topic: Encyclopedia › Technology and the built world › Transport and spaceflight › Aviation › Aircraft › Experimental and advanced aircraft › X-planes, prototypes, and demonstrators › Cancelled civil aircraft projects*
*Initially written Sep 17, 2026 · Reviewed: Sep 20, 2026; Oct 15, 2026 · Edited: Oct 15, 2026 · Last review: Oct 15, 2026*
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