SAM-A-1 GAPA

Last updated
SAM-A-1 GAPA
Boeing ground-to-air pilotless aircraft -GAPA-1949.jpg
Final check of Model 601 prior to launching at Holloman Air Force Base, c. 1949.
Place of originUSA
Service history
In service1946-1950
Used by United States Air Force
Production history
Designed1946
Manufacturer Boeing
Specifications (Model 603)
Mass2,000 pounds (910 kg) w/o booster [1]
Length21 ft (6.4 m) w/o booster
Diameter10 in (250 mm) [2]
Engine
  • Sustainer: Ramjet
  • Booster: Solid-fueled rocket
Wingspan9 ft (2.7 m)
Operational
range
31 mi (50 km) [3]
Flight ceiling59,000 ft (18,000 m)
Maximum speed 1,500 mph (2,400 km/h; Mach 2.0)
Guidance
system
Midcourse: Beam riding
Terminal: Active radar homing
Launch
platform
Rail Launcher

Boeing's Ground-to-Air Pilotless Aircraft (GAPA) was a short-range anti-aircraft missile (SAM) developed in the late 1940s by the US Army Air Force, and then the US Air Force after 1948. It was given the reference number SAM-A-1, the first Surface-to-Air Missile (SAM) in the 1947 tri-service designation system. By 1950 over 100 test rockets had been launched using a variety of configurations and power plants, with one launch in 1949 setting the altitude record for a ramjet powered vehicle at 59,000 ft (18,000 m).

Contents

GAPA faced strong competition from the US Army's Nike missile system, and was eventually cancelled in favour of Nike for deployment. The GAPA work was later re-used by the Boeing and Project Wizard team at the Michigan Aeronautical Research Center to develop a much longer-ranged missile, the CIM-10 Bomarc. Bomarc would end up competing with the Army's Hercules missile, and was deployed only in small numbers.

History

German work

The inherent inaccuracy of anti-aircraft artillery means that when shells reach their targets they are randomly distributed in space. This distribution is much larger than the lethal radius of the shells, so the chance that any one shell will successfully hit the target is very small. Successful anti-aircraft gunnery therefore requires as many rounds to be fired as possible, increasing the chances that one of the rounds will get a "hit". German gunners estimated that an average of 2,800 shells were required to down a single Boeing B-17. [4]

Flying faster means that the aircraft passes through the range of a gun more rapidly, reducing the number of rounds a particular gun can fire at that aircraft. Flying at higher altitudes has a similar effect, as it requires larger shells to reach those altitudes, and this typically results in slower firing rates for a variety of practical reasons. Aircraft using jet engines basically double the speed and altitude of conventional designs, so limiting the number of shells that the chance of hitting the bomber essentially dropped to zero. As early as 1942, German flak commanders were keenly aware of the problem, and expecting to face jet bombers, they began a missile development program to supplant their guns. [5]

Of the many programs that resulted, the designs fell into two categories. One used a high-speed missile that flew directly up at the target. With enough speed the missile did not have to "lead" the target by a great amount, as the bomber moved only a short distance in the time between launch and interception. A second class used aircraft-like designs that were first boosted to altitude in front of the bombers, then flew at them on intercept courses at much lower speeds. These were essentially radio-guided drone versions of the Messerschmitt Me 163 rocket-propelled interceptor aircraft carrying very large warheads.

US Army program

The western allies maintained air superiority for much of the war and development of new anti-aircraft systems was not as urgent. Nevertheless, by the mid-war period the US Army had reached the same conclusion as their German counterparts; flak was simply no longer useful. [6] Accordingly, in February 1944 the Army Ground Forces sent the Army Service Forces (ASF) a request for information on the possibility of building a "major caliber anti-aircraft rocket torpedo". The ASF concluded that it was simply too early to tell if this was possible, and suggested concentrating on a program of general rocket development instead. [6]

The introduction of German jet-powered bombers late in 1944 led to a re-evaluation of this policy, and on 26 January 1945 the Army Chief of Ordnance issued a requirement for a new guided missile weapon system. Like the German efforts, the Army designs quickly fell into two groups, high-speed line-of-sight weapons for short ranges, and airplane-like systems that flew at lower speeds but offered longer range. Eventually two such programs were selected; Bell Labs, a world leader in radar, radio control and automated aiming systems (see Hendrik Wade Bode) [7] won the contract for a short-range weapon known as Project Nike. Boeing led development of an aircraft-like longer range system, GAPA, designated project MX-606. [3]

GAPA

Although GAPA was based on similar principles as earlier German designs, it evolved into an entirely different concept; GAPA designs were long and thin and looked like missiles, not aircraft. Aerojet was selected to build solid-fuel boosters, while Boeing tried a wide variety of engine designs for the upper stage. The first test shot of an unguided GAPA airframe design took place on 13 June 1946 from a 100 ft × 100 ft (30 m × 30 m) launch pad at the World War II Wendover Bombing and Gunnery Range on the western edge of the Bonneville Salt Flats. [8] These early "Model 600" designs were for aerodynamic testing only, and used solid fuel in both stages. [9] Over the following two week period, a total of 38 launches were conducted, ending on 1 July.

In a report to the President's Air Policy Commission in October, Boeing reported the range of the system at 30 miles (48 kilometres). The need for a 50-mile range, Mach 0.9 version was identified for the "interim" air defense system. [10] In early 1948 the USAF was "ready to buy complete GAPA missiles for test and training purposes, [but] guidance components were not available", and of the planned $5.5 million for GAPA, only $3 million was provided in July 1948. [11]

At the end of 1948, Air Materiel Command was instructed to buy 70 test vehicles. [12] Over 74 launches took place at the Alamogordo Guided Missile Test Base [13] beginning on 23 July 1947 (the 39th launch). [14] A ramjet powered Model 602 first flew on 14 November 1947, and a liquid-fuel rocket Model 601 on 12 March 1948. [15] By the end of the test program in 1950, 114 launches were carried out, with the last on 15 August 1950. [16]

By 1949 the performance of the competing Nike design had demonstrated capabilities similar to GAPA, at about 25 miles (40 kilometres), and was much closer to being ready for deployment. The Department of Defense (DoD) saw no need for two systems with similar performance, and inter-service fighting since the 1948 creation of the Air Force was a constant problem for the DoD. They eventually decided the matter in 1949 when the Joint Chiefs of Staff determined that each branch of the armed forces would conduct missile development according to its mission [17] and handed the Army control of all short-range air defences, whether missile or gun. [12] GAPA was cancelled outright, [18] and a new contract for a much longer-range weapon was created under MX-1599. To keep GAPA development alive in the meantime, the US Air Force re-directed funding from an anti-ballistic missile program, Project Thumper, which was being ended in favour of a more advanced system, Project Wizard. [19]

Computer work

Boeing built two computers to aid with development of the GAPA effort. The first was the BEMAC, Boeing Electro-Mechanical Analog Computer, which was used for various calculations and aerodynamic research. The second, BEAC, the Boeing Electronic Analog Computer, was developed in 1949 in Seattle to aid calculations in the GAPA project. BEAC proved so useful that other divisions within the company started asking for time on the system. This led the Physical Research Unit to build further examples of improved models of BEAC for the Acoustics and Electrical Department, Aerodynamics, Power Plant, Mechanical Equipment and Structures Department. Given the success of the BEAC design, the company began to offer it commercially in 1950. Sales continued through the 1950s. [20]

Bomarc

The new MX-1599 also ran into development and funding problems, and repeated early history when the project was joined by the team from the Michigan Aeronautical Research Center (MARC) working on Project Wizard. Wizard was based on a high performance missile, existing only on paper, able to intercept missiles travelling at up to 4,000 mph (6,400 km/h) at altitudes up to 500,000 ft (150 km). Wizard had also put considerable thought into the problem of early detection and communications needed for interceptions that lasted only minutes. The combination of the two teams, from Boeing and MARC, resulted in the new BOMARC name. At the time the Air Force considered missiles to be unmanned aircraft, and assigned the new missile the "F-99" name, considering its role to be the same as a fighter aircraft. This was later changed to "Interceptor Missile", IM-99. and finally CIM-10 Bomarc when the 1963 United States Tri-Service missile and drone designation system was introduced. [21]

Bomarc development dragged on, and by 1956, less than 25 test launches had taken place, many of them failures. By this point, the Army had begun early production of its greatly improved Nike Hercules missile, which offered high supersonic speeds, intercept altitudes as high as 100,000 ft (30 km), and ranges on the order of 75 mi (121 km). Although Bomarc's range was much greater than Hercules, the mission of protecting cities was adequately served, and Hercules was dramatically simpler, cheaper and more reliable (Bomarc was estimated to be ready to fire 25% of the time or less). [22]

Description

There were three main models of the GAPA vehicle, and their layout differed considerably. All were "missile like" with four cropped-delta fins at the extreme rear of a cylindrical fuselage capped with an ogive nose cone. Aerodynamic lift for control was provided by a long wing running along the upper surface of the fuselage, only slightly wider that the body. The wing tapered to a point just behind the nose cone. The booster was about the same length as the missile, although slightly larger in diameter and featuring much larger cropped-delta fins.

GAPA used beam riding guidance, in which the missile attempts to keep itself centred in the middle of a radar signal that is pointed directly at the target. This system allows a single powerful radar to act as both the tracking and guidance system. However, beam riding also means that the missile has to fly directly at its target, and therefore cannot "lead" it to a calculated intercept point. This means of guidance is generally inefficient as it requires the missile to continue maneuvering throughout the approach as the radar is moved to continue tracking the target. This can be significant in the case of high-speed aircraft.

External image
Searchtool.svg Alamogorda launch site map (p. 18) & "GAPA Model 601" on launcher (p. 20)

See also

Related Research Articles

<span class="mw-page-title-main">CIM-10 Bomarc</span> A long-range surface-to-air missile

The Boeing CIM-10 BOMARC was a supersonic ramjet powered long-range surface-to-air missile (SAM) used during the Cold War for the air defense of North America. In addition to being the first operational long-range SAM and the first operational pulse doppler aviation radar, it was the only SAM deployed by the United States Air Force.

<span class="mw-page-title-main">Surface-to-air missile</span> Ground-launched missile designed to attack aerial targets

A surface-to-air missile (SAM), also known as a ground-to-air missile (GTAM) or surface-to-air guided weapon (SAGW), is a missile designed to be launched from the ground to destroy aircraft or other missiles. It is one type of anti-aircraft system; in modern armed forces, missiles have replaced most other forms of dedicated anti-aircraft weapons, with anti-aircraft guns pushed into specialized roles.

<span class="mw-page-title-main">Project Nike</span> Missile program of the United States Army

Project Nike was a U.S. Army project, proposed in May 1945 by Bell Laboratories, to develop a line-of-sight anti-aircraft missile system. The project delivered the United States' first operational anti-aircraft missile system, the Nike Ajax, in 1953. A great number of the technologies and rocket systems used for developing the Nike Ajax were re-used for a number of functions, many of which were given the "Nike" name . The missile's first-stage solid rocket booster became the basis for many types of rocket including the Nike Hercules missile and NASA's Nike Smoke rocket, used for upper-atmosphere research.

<span class="mw-page-title-main">White Sands Missile Range</span> Military testing area in New Mexico, US

White Sands Missile Range (WSMR) is a United States Army military testing area and firing range located in the US state of New Mexico. The range was originally established as the White Sands Proving Ground on 9 July 1945. White Sands National Park is located within the range.

<span class="mw-page-title-main">Nike Hercules</span> Type of surface-to-air missile

The Nike Hercules, initially designated SAM-A-25 and later MIM-14, was a surface-to-air missile (SAM) used by U.S. and NATO armed forces for medium- and high-altitude long-range air defense. It was normally armed with the W31 nuclear warhead, but could also be fitted with a conventional warhead for export use. Its warhead also allowed it to be used in a secondary surface-to-surface role, and the system also demonstrated its ability to hit other short-range missiles in flight.

<span class="mw-page-title-main">Lockheed X-7</span> Experimental aircraft to test ramjet engines and missile guidance technology

The Lockheed X-7 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.

<span class="mw-page-title-main">SM-64 Navaho</span> 1950s supersonic intercontinental cruise missile

The North American SM-64 Navaho was a supersonic intercontinental cruise missile project built by North American Aviation (NAA). The final design was capable of delivering a nuclear weapon to the USSR from bases within the US, while cruising at Mach 3 at 60,000 feet (18,000 m) altitude. The missile is named after the Navajo Nation.

<span class="mw-page-title-main">Air Force Missile Development Center</span> Military unit

The Air Force Missile Development Center and its predecessors were Cold War units that conducted and supported numerous missile tests using facilities at Holloman Air Force Base, where the center was the host unit

<span class="mw-page-title-main">LIM-49 Spartan</span> Anti-ballistic missile

The LIM-49 Spartan was a United States Army anti-ballistic missile, designed to intercept attacking nuclear warheads from Intercontinental ballistic missiles at long range and while still outside the atmosphere. For actual deployment, a five-megaton thermonuclear warhead was planned to destroy the incoming ICBM warheads. It was part of the Safeguard Program.

<span class="mw-page-title-main">Sprint (missile)</span> Anti-ballistic missile

The Sprint was a two-stage, solid-fuel anti-ballistic missile (ABM), armed with a W66 enhanced-radiation thermonuclear warhead used by the United States Army from 1975-1976. It was designed to intercept incoming reentry vehicles (RV) after they had descended below an altitude of about 60 kilometres (37 mi), where the thickening air stripped away any decoys or radar reflectors and exposed the RV to observation by radar. As the RV would be traveling at about 5 miles per second, Sprint had to have phenomenal performance to achieve an interception in the few seconds before the RV reached its target.

<span class="mw-page-title-main">Lockheed AQM-60 Kingfisher</span> Type of aircraft

The AQM-60 Kingfisher, originally designated XQ-5, was a target drone version of the USAF's X-7 ramjet test aircraft built by the Lockheed Corporation. The aircraft was designed by Kelly Johnson, who later created the Lockheed A-12 and its relatives, such as the Lockheed SR-71 Blackbird and Lockheed YF-12.

<span class="mw-page-title-main">RIM-50 Typhon</span> Long range surface-to-air missile

Typhon was a missile system developed by the United States Navy in the late 1950s, intended to serve as an integrated air-defense system for Navy fleets. Consisting of the SAM-N-8 Typhon LR, later designated RIM-50A, and the SAM-N-9 Typhon MR, later RIM-55A, paired with the AN/SPG-59 radar system, the cost and expense of the Typhon system led to it being cancelled in favor of the Standard Missile program.

<span class="mw-page-title-main">Bold Orion</span> Air-launched ballistic missile

The Bold Orion missile, also known as Weapons System 199B (WS-199B), was a prototype air-launched ballistic missile (ALBM) developed by Martin Aircraft during the 1950s. Developed in both one- and two-stage designs, the missile was moderately successful in testing, and helped pave the way for development of the GAM-87 Skybolt ALBM. In addition, the Bold Orion was used in early anti-satellite weapons testing, performing the first interception of a satellite by a missile.

<span class="mw-page-title-main">Nike Zeus</span> Type of anti-ballistic missile

Nike Zeus was an anti-ballistic missile (ABM) system developed by the US Army during the late 1950s and early 1960s that was designed to destroy incoming Soviet intercontinental ballistic missile warheads before they could hit their targets. It was designed by Bell Labs' Nike team, and was initially based on the earlier Nike Hercules anti-aircraft missile. The original, Zeus A, was designed to intercept warheads in the upper atmosphere, mounting a 25 kiloton W31 nuclear warhead. During development, the concept changed to protect a much larger area and intercept the warheads at higher altitudes. This required the missile to be greatly enlarged into the totally new design, Zeus B, given the tri-service identifier XLIM-49, mounting a 400 kiloton W50 warhead. In several successful tests, the B model proved itself able to intercept warheads, and even satellites.

<span class="mw-page-title-main">MIM-3 Nike Ajax</span> First operational guided surface-to-air missile

The United States Army's Nike Ajax was the world's first operational guided surface-to-air missile (SAM), entering service in 1954. Nike Ajax was designed to attack conventional bomber aircraft flying at high subsonic speeds and altitudes above 50,000 feet (15 km). Nike was initially deployed in the US to provide defense against Soviet bomber attacks, and was later deployed overseas to protect US bases, as well as being sold to various allied forces. Some examples remained in use until the 1970s.

<span class="mw-page-title-main">Project Wizard</span>

Project Wizard was a Cold War-era anti-ballistic missile system to defend against short and medium-range threats of the V-2 rocket type. It was contracted by the US Army Air Force in March 1946 with the University of Michigan's Aeronautical Research Center (MARC). A similar effort, Project Thumper, started at General Electric.

<span class="mw-page-title-main">Boeing CQM-121 Pave Tiger</span> Type of aircraft

The Boeing CQM-121 Pave Tiger was an unmanned aerial vehicle developed by Boeing for use by the United States Air Force. Intended for the Suppression of Enemy Air Defenses (SEAD) role, the drone reached the flight-test stage before cancellation.

The Cherokee was an experimental rocket built by the Cook Electric Co. for use by the United States Air Force during the 1950s for the testing of ejection seats.

The SAM-A-19 Plato was an anti-ballistic missile project developed by the United States Army in the mid 1950s. By modern standards, it would be considered a theatre ballistic missile (TBM) defense system (TBMD), providing protection to the Army field units from Warsaw Bloc short and medium-range weapons.

<span class="mw-page-title-main">AAM-N-10 Eagle</span> Canceled US air-to-air missile

The AAM-N-10 Eagle was a long-range air-to-air missile developed by the Bendix Corporation for use by the United States Navy. Intended for carriage by the Douglas F6D Missileer fleet defense fighter, the Eagle program was cancelled before testing could begin, but the lessons learned were used in the development of the AIM-54 Phoenix missile.

References

Citations

  1. ↑ Parsch 2004.
  2. ↑ "Boeing: GAPA (Ground-to-Air Pilotless Aircraft)". boeing.com. 2014. Retrieved 31 January 2014.
  3. 1 2 Rosenberg 1964, p. 76.
  4. ↑ Westerman 2001, p. 197.
  5. ↑ Westerman 2001, p. 11.
  6. 1 2 Cagle 1973, I.
  7. ↑ FAS 1999.
  8. ↑ ACC 1996, p. 11.
  9. ↑ Bushnell 1986, pp. 1–2.
  10. ↑ McMullen 1980, p. 50.
  11. ↑ McMullen 1980, p. 51.
  12. 1 2 McMullen 1980, p. 90.
  13. ↑ Bushnell 1986, p. 1.
  14. ↑ "Rocket Trials Center Moved". Eugene Register-Guard. 24 July 1947. p. 6.
  15. ↑ Bushnell 1986, p. 2.
  16. ↑ Bushnell 1986, p. 3.
  17. ↑ HAER 1966.
  18. ↑ McMullen 1980, p. 91.
  19. ↑ McMullen 1980, pp. 90–91.
  20. ↑ Small, James (17 June 2013). The Analogue Alternative... pp. 47–48. ISBN   9781134699025 . Retrieved 9 August 2013.
  21. ↑ Parsch 2002
  22. ↑ Cagle 1973, pp. 144–148.

Bibliography

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.