Function | Sounding rocket |
---|---|
Manufacturer | Douglas Aircraft Corporation, JPL, Aerojet |
Country of origin | United States |
Size | |
Height | 7.37 m (24.2 ft) |
Diameter | 30 cm (12 in) |
Stages | 1 |
Launch history | |
Status | Retired |
Launch sites | White Sands Missile Range, Cape Canaveral |
First flight | October 11, 1945 |
Last flight | July 29, 1950 |
Booster stage – Tiny Tim | |
Gross mass | 344.4 kg (759 lb) |
Propellant mass | 67.4 kg (149 lb) |
Maximum thrust | 220 kN (49,000 lbf) |
Burn time | .6 seconds |
Propellant | solid |
Sustainer stage –WAC Corporal | |
Empty mass | 134.6 kg (297 lb) |
Gross mass | 313.3 kg (691 lb) |
Powered by | Aerojet 38ALDW-1500 |
Maximum thrust | 6.7 kN (1,500 lbf) |
Burn time | 47 seconds |
Propellant | RFNA + furfuryl alcohol |
The WAC Corporal was the first sounding rocket developed in the United States and the first vehicle to achieve hypersonic speeds. [1] It was an offshoot of the Corporal program,that was started by a partnership between the United States Army Ordnance Corps and the California Institute of Technology (named "ORDCIT") in June 1944 with the ultimate goal of developing a military ballistic missile. [2]
The California Institute of Technology had been fostering a group of rocket engineers in the 1930s at their Guggenheim Aeronautical Laboratory (GALCIT) including Frank Malina,Jack Parsons,and Edward Forman. [3] They became known as the "suicide squad" because so many of their early experiments at the Laboratory blew up. [4] [3] Some of the GALCIT enthusiasts had founded a business to manufacture rocket motors called Aerojet. [5]
During the first years of World War II,GALCIT had pursued the development of both solid and liquid-fueled Jet Assisted Take Off (JATO) boosters to aid aircraft take off performance. [6] As the group had experimented with rockets for several years before the war they were selected by the Army to pursue ballistic rocket development.
The first rocket designed by the group for the Army was designated as XFS10S100-A,also known as the Private,that being the first Army enlisted rank. [7] The second ORDCIT project,which became the Corporal,named for the next Army enlisted rank,was a project originally named XF30L 20,000. [8] The Corporal project envisioned a liquid propellant missile of 30-inch (760 mm) diameter and a power of 20,000 pounds-force (89 kN). [8] The Signal Corps had created the requirement for a sounding rocket to carry 25 pounds (11 kg) of instruments to 100,000 feet (30 km) or higher. [9] This was merged with a requirement of the Rocket R&D Division of the Ordnance Corps for a test vehicle. [9] Frank Joseph Malina of the Jet Propulsion Laboratory (JPL) proposed the development of a liquid-fueled sounding rocket to meet this request,thus providing a practical developmental step towards the ultimate Corporal missile. [10] [11]
The theoretical work setting the stage for the WAC Corporal was established in a 1943 paper "A Review and Preliminary Analysis of Long-Range Rocket Projectiles" by Malina and Hsue-Shen Tsien. [12] [13] Design was started by Frank Malina and Homer Joe Stewart to meet the Signal Corps' request with their study "Considerations of the Feasibility of Developing a 100,000-ft. Altitude Rocket." [14] The final design work was done by a team of persons specializing in particular areas and involved significant efforts to derive performance from theoretical means (a relatively new method for America rocketry). [15] The key persons responsible were M.M. Mills (booster),P.J. Meeks (sounding rocket),W.A. Sandburg and W.B. Barry (launcher and WAC nose),S.J. Goldberg (field tests) and H.J. Stewart (external ballistics) and G,Emmerson (photography). [16]
For propulsion,the 38ALDW-1500 Aerojet liquid-fueled engine was chosen,which had been developed as a JATO system for Navy flying boats. [17] [18] The 38ALDW-1500 was modified for hypergolic propellants,with red fuming nitric acid as the oxidizer and furfuryl alcohol as the fuel. [19] [20] The WAC Corporal was intended to use a booster derived from the Tiny Tim air-to-ground attack rocket to gain sufficient speed along a launch tower for the Corporal's three tail fins to provide passive stability. [21] [15] Despite the emphasis upon a theoretical approach,it was deemed necessary to empirically prove the Corporal's aerodynamics,especially the three fin configuration,so a solid propellant one-fifth scale model called the Baby WAC was tested from a scaled-down launcher in July 1945. [22] [23] Four Baby WACs were flown. [24]
The design of the WAC Corporal was innovative in that main structure containing the oxidizer,fuel,and pressurizing air tanks was of monocoque design,and that it had only three stabilizing fins,rather than the four that the Army preferred. [22] Since the WAC Corporal was conceived as an atmospheric sounding rocket to be used in part near populated locations,it was provided with a parachute recovery system for the rocket itself,along with a separate system for recovering the Signal Corps radiosonde payload. [25] [26]
The production of the WAC Corporal was by Douglas Aircraft Corporation with critical parts supplied by JPL and the engines by Aerojet. [27]
The WAC Corporal test program began at White Sands Proving Grounds in late September 1945 with a series of booster tests lofting dummy upper stages. [28] [29] These were the first missiles launched at White Sands. They were launched from what became LC-33,which was also the launch site for many other early missiles such as the V-2,Viking and Hermes. [30] [31] These first launches tested not only the booster,but the launcher and firing controls,as well as providing practice for the radar and camera crews. [16] October saw two launches of the WAC Corporal with one-third propellant load followed by six fully-fueled flights. Several of these flights reached altitudes of approximately 235,000 feet (72 km). [29] [32] Performance varied because of several factors,including variation in the gross weight from 683 to 704 pounds (310 to 319 kg),with empty weights from 289 to 310 pounds (131 to 141 kg). [21]
The missions flown during the WAC Corporal first series were:
Radar tracking was difficult,as above 90,000 feet (27 km) the radar return was too small to be detected,and radiosonde signals were not received. [33] No previous American liquid-fueled rocket had exceeded a tiny fraction of the altitudes the WAC Corporal regularly achieved. [34] [35] It was decided on November 9,1945,to alter the WAC Corporal design to improve upon it for another series of flights. [36] This redesigned rocket was first deemed "Sergeant" in keeping with the JPL naming scheme but was soon renamed WAC Corporal B. [37] The name "Sergeant" was later used for a solid propellant missile designed for the United States Army at JPL. [38] Design of the WAC Corporal B was initiated in March 1946 with P.J. Meeks as Project Coordinator,and differed significantly in detail while its basic shape remained the same. It was 4 inches (10 cm) longer,weighed 100 pounds (45 kg) less,and contained 40 pounds (18 kg) less propellant. [39] The designs of the fuel pressurization system and fuel valves were simplified. [40] It had a shorter engine with redesigned injectors weighed 12 pounds (5.4 kg),rather than the longer 50-pound (23 kg) engine of the WAC Corporal A. [39] [41] The drastically redesigned rocket body used separate tanks of dissimilar materials. [42] [40] Larger,lighter fins were supplied,which proved problematic on the first WAC Corporal B flight on December 6,1946. [40] [29]
The flights during the second series of WAC Corporal flights were:
The WAC Corporal program was an extremely successful test program. The last 6 WAC Corporal Bs to fly were used in the Bumper program as the second stage atop captured V-2 missiles in early air-light and staging experiments. [43] [44] For Bumper,the WAC Corporal was modified to provide stability in excess of Mach 5 by increasing the number of fins to four and increasing their size. [45] [46] The WAC Corporal had to be modified so that the engine ignition would be initiated by the integrating accelerometer of the V-2 stage just before cutoff of the V-2 engine. [47] The WAC Corporal was spin-stabilized by two solid rockets placed between the oxidizer and fuel tanks. [48] The Bumper/WAC had a payload capacity of 50 pounds and carried a Doppler transmitter/receiver which transmitted the nose cone temperature as well as velocity information. [49] There were 6 Bumper flights from White Sands,the first two carrying solid-fueled dummy WACs. [50] Flight number six had a failure on the V-2. [50] Bumper 7 and 8,the last two flights of the Bumper program,were the first launches from the new Joint Long-Range Proving Ground at Cocoa Beach,Florida,which would later be known as Cape Canaveral. The reason for the move was the intention to use a depressed trajectory to achieve velocities in the vicinity of Mach 7 from 120,000 to 150,000 feet (37 to 46 km). This would entail flights downrange in excess of 250 miles (400 km),which would exceed the boundaries of White Sands. [51]
The WAC/Bumper flights were:
Bumper 7's WAC Corporal,the last one ever to fly,achieved Mach 9,the highest speed ever achieved by a projectile in the atmosphere at the time. [52]
The WAC Corporal found itself in direct competition in its designed role,with the V-2 offering much larger payload capabilities that became available in the General Electric-operated Hermes program in April 1946. [53] It was also in competition with the Aerobee,a direct descendant of the Corporal,which was tested in late 1947 and became fully operational in spring 1948. [54] [55] Another competitor was the Neptune sounding rocket,later known as the Viking. [56] The V-2 could lift 2,200 pounds (1,000 kg) to 128 miles (206 km),the Aerobee around 150 pounds (68 kg) to over 70 miles (110 km),and Viking 500 pounds (230 kg) to 100 miles (160 km). All three of these offered better performance than the Corporal's 25-pound (11 kg) payload. In terms of pounds to altitude per dollar,the Corporal also lost to the competition:Each WAC Corporal B cost US$8,000(equivalent to $109,200 in 2023),for $320/lb to apogee,while each V-2 reassembled from captured parts cost around $30,000 ($14/lb),and the Aerobee cost $18,500 ($123/lb). [57]
While the WAC Corporal was soon replaced in its intended role of sounding rocket,its legacy was long-lasting. Its 38ALDW-1500 engine was the direct predecessor of the Nike Ajax's A21AL-2600 and Aerobee's 45AL-2600,and was developed into the AJ10 series,which includes the AJ10-37 engine on the second stage of the world's first purpose-built satellite launch vehicle,Vanguard. [17] [58] [59] Other AJ10 series members include the AJ10-101,which powered the Able upper stage on a variety of launch vehicles,the AJ10-137 Service Propulsion System on the Apollo spacecraft,and the AJ10-190 that acted as the Space Shuttle Orbital Maneuvering System. [60] [58] [61] WAC Corporals are on display at the National Air and Space Museum and in the White Sands Missile Range Museum.
The origin of the acronym "WAC" in WAC Corporal has been claimed to stand for multiple different phrases. Some White Sands historians (Kennedy,DeVorkin,Eckles) have claimed it means "Without Attitude Control". [62] [63] [64] In "Bumper 8:50th Anniversary of the First Launch on Cape Canaveral,Group Oral History," William Pickering attributed it to "Women's Army Corps". [65]
The earliest public reports of the WAC designation are a series of Aviation Week articles,which seem to support "Women's Army Corps" being the derivation of the acronym. In its March 18,1946 issue,Aviation Week noted,"[u]nder the amusing security code designation of 'WAC Corporal' the project was initiated in 1944...." In the June 1,1946 of Aviation Week,an article describes how the WAC Corporal "is launched from a triangular 100 ft. launching tower,and thereafter goes its own merry way," and claims that "[t]hese characteristics suggest some of the reasons for the female appellation of the 'WAC,' the 'Corporal' coming from the fact that some Army rockets are designated by familiar ranks."
The SM-65 Atlas was the first operational intercontinental ballistic missile (ICBM) developed by the United States and the first member of the Atlas rocket family. It was built for the U.S. Air Force by the Convair Division of General Dynamics at an assembly plant located in Kearny Mesa, San Diego.
The Aerobee rocket was one of the United States' most produced and productive sounding rockets. Developed by the Aerojet Corporation, the Aerobee was designed to combine the altitude and launching capability of the V-2 with the cost effectiveness and mass production of the WAC Corporal. More than 1000 Aerobees were launched between 1947 and 1985, returning vast amounts of astronomical, physical, aeronomical, and biomedical data.
A sounding rocket or rocketsonde, sometimes called a research rocket or a suborbital rocket, is an instrument-carrying rocket designed to take measurements and perform scientific experiments during its sub-orbital flight. The rockets are used to launch instruments from 48 to 145 km above the surface of the Earth, the altitude generally between weather balloons and satellites; the maximum altitude for balloons is about 40 km and the minimum for satellites is approximately 121 km. Certain sounding rockets have an apogee between 1,000 and 1,500 km, such as the Black Brant X and XII, which is the maximum apogee of their class. For certain purposes Sounding Rockets may be flown to altitudes as high as 3,000 kilometers to allow observing times of around 40 minutes to provide geophysical observations of the magnetosphere, ionosphere, thermosphere and mesosphere. Sounding rockets have been used for the examination of atmospheric nuclear tests by revealing the passage of the shock wave through the atmosphere. In more recent times Sounding Rockets have been used for other nuclear weapons research. Sounding rockets often use military surplus rocket motors. NASA routinely flies the Terrier Mk 70 boosted Improved Orion, lifting 270–450-kg (600–1,000-pound) payloads into the exoatmospheric region between 97 and 201 km.
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The RTV-G-4 Bumper was a sounding rocket built by the United States. A combination of the German V-2 rocket and the WAC Corporal sounding rocket, it was used to study problems pertaining to two-stage high-speed rockets. The Bumper program launched eight rockets between May 13, 1948 and July 29, 1950. The first six flights were conducted at the White Sands Missile Range; the seventh launch, Bumper 8 on July 24, 1950, was the first rocket launched from Cape Canaveral.
The RTV-A-2 Hiroc was a product of the United States' first effort to develop an intercontinental ballistic missile (ICBM). The project was named MX-774. The project was canceled in 1947, but leftover funds were used to build and launch three of the planned 10 research vehicles designated RTV-A-2. The design included several innovations; the gimbaled thrust chambers provided guidance control, the internal gas pressure was used to support the airframe and the nose cap was separable. All of these concepts were later used on the Atlas missile and the first two on the Viking rocket. Also developed as part of MX-774 was the Azusa guidance system which was not used on the Hiroc missile but did contribute to the Atlas missile as well as many other early guided missiles launched from Cape Canveral.
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The Guggenheim Aeronautical Laboratory at the California Institute of Technology (GALCIT), was a research institute created in 1926, at first specializing in aeronautics research. In 1930, Hungarian scientist Theodore von Kármán accepted the directorship of the lab and emigrated to the United States. Under his leadership, work on rockets began there in 1936. GALCIT was the first—and from 1936 to 1940 the only—university-based rocket research center. Based on GALCIT's JATO project at the time, the Jet Propulsion Laboratory was established under a contract with the United States Army in November 1943.
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Private was an experimental rocket developed by the California Institute of Technology on behalf of the United States Army. Tested in two different configurations, it provided the proof of concept that a fin-stabilised ballistic missile was technologically feasible, and led to the development of the Corporal ballistic missile. The Private was the first in a series of JPL rocket designs for the US Army, whose names correspond to the progression in Army enlisted ranks, leading to WAC Corporal, Corporal E, MGM-5 Corporal and finally Sergeant.
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German V-2 rockets captured by the United States Army at the end of World War II were used as sounding rockets to carry scientific instruments into the Earth's upper atmosphere, and into sub-orbital space, at White Sands Missile Range (WSMR) for a program of atmospheric and solar investigation through the late 1940s. Rocket trajectory was intended to carry the rocket about 100 miles (160 km) high and 30 miles (48 km) horizontally from WSMR Launch Complex 33. Impact velocity of returning rockets was reduced by inducing structural failure of the rocket airframe upon atmospheric re-entry. More durable recordings and instruments might be recovered from the rockets after ground impact, but telemetry was developed to transmit and record instrument readings during flight.
The ORDCIT program to develop a ballistic missile called Corporal was a progressive one. The original design was called XF30L20,000 which envisioned a 30 in (760 mm) diameter liquid fueled missile with a 20,000 lbf (89 kN) thrust engine and was ventured in the summer of 1944. The WAC Corporal sounding rocket was developed in 1945, providing experience with liquid fueled ballistic rocketry. The second phase gave experience with a redesigned and refined rocket and engine the following year. What was learned was applied to the Corporal program.
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