The JB-2: America’s Copy of the V-1 Missile

Conceived following Allied intelligence reports of the German V-1 flying-bomb, the JB-2 was intended to be America’s answer to German missile technology and was created through meticulous design-copying followed by technological improvements.

Although never used in a combat situation, the JB-2 was one of America’s first successful attempts at creating a self-guided aerial bomb and later paved the way for the development of many modern guided rocket and cruise missile systems.

 

Origins

Prior to the Second World War, German engineers had devised plans for an unmanned, flying bomb and conducted further research into whether a remote-controlled drone or a guided rocket weapon could be produced. Various ideas and theories were discussed, including a remote-controlled aircraft without a pilot that could return to base after dropping its payload.

After the war began, some of the earlier design ideas were developed into what would become the V-1 flying-bomb. In June 1944, the V-1 became the world’s first operational cruise missile to be used in combat and marked a significant advancement in weapons technology: it was relatively cheap to manufacture, could be launched either from the ground or an aircraft, and had the potential to be devestating when it managed to reach a target.

An original V-1 rocket in the Imperial War Museum, London. Image by Peter Trimming CC BY-SA 2.0.

However, the V-1 ultimately proved to be more of a terror threat than a weapon of mass destruction owing to its unreliable accuracy and limited guidance system.

RAF defense measures managed to intercept and stop many V-1s prior to impact and those launched from Luftwaffe aircraft were sometimes known to explode prematurely.

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Although the V-1 was developed in secret, American military intelligence had become aware of Nazi experiments involving unmanned rockets and missiles by 1942. The Germans had tried to test early V-1s over the Baltic Sea and in August 1942, a prototype crashed on the Danish Island of Bornholm. A local Danish navy officer quickly photographed and sketched the wreckage before handing his discovery over to the Allies.

The V-1 flying bomb’s guidance system. It maintained a pre-determined flight path, but didn’t allow for precise targeting and could be overwhelmed in some scenarios.

Allied aerial reconnaissance of the V-1 production and launch sites on the German island of Usedom and intelligence information, often smuggled out by labourers from occupied countries forced to work on Nazi military projects, led to design schematics and drawings of the V-1 being sent to Britain. Responding to this information, the US military began the process of conceiving their own unmanned cruise missile.

Development

Aided with intelligence provided by the British government and later intact examples of crashed V-1s transported to the United States, aerospace engineers at Wright Field Air Base began working on a reverse copy of the Argus As 014 pulsejet engine which powered the V-1 to see what improvements could be made.

Who would be in control of the guided missile program came under a jurisdictional dispute between the US Army’s ground force and the Army Air Force. Military high command ultimately ruled in favour of the Army Air Force on the basis that a proposed cruise missile had wings and flew. Once the dispute was initially settled, research and development on the new weapon began.

The first attempt at a guided flying bomb had been made by the Northrop Aircraft company in July 1944 and was named the JB-1. The initial JB-1 design resembled a glider instead of a cruise missile and was powered by a turbo-jet engine. The explosive warhead was encased in a bomb compartment in the middle. It was also first flown with a pilot to test its capabilities.

This is a JB-1, an unmanned flying bomb powered by two turbojets. The pods either side of the central fuselage would contain explosives.

American engineers found that whilst mimicking the V-1’s overall design was relatively straightforward, devising a suitable means to launch the missile safely often proved more difficult. A special testing range, Range 64, was constructed at Eglin Army Airfield Base as a proving ground for cruise missile research and experimented with various methods to launch it into the air.



An unmanned test in December 1944 resulted in the JB-1 stalling and crashing once it left a launch ramp at Range 64. Further research into the JB-1 program was subsequently shelved when it was found the engine did not meet performance standards and the design was too expensive.

However, as more intelligence findings and examples of the V-1 continued to be supplied by the British, the Republic Aviation Corp was tasked with building the first JB-2 missiles at Wright Field. Like the JB-1, the design of the JB-2 borrowed heavily from the V-1 but tried to make changes to the exterior design and engine casing. The German-made pulsejet engine was also more cost-effective to copy and mass produce compared to developing the turbojet that had powered the JB-1.

This is the JB-10, a development of the JB-1. The JB-1’s turbojets were replaced by a single Ford PJ31 pulsejet, the same type used on the JB-2.

However, initial tests confirmed that the existing V-1 guidance system could be faulty, and the American engineers sought to research methods to exercise more precise control of the JB-2 using radar and radio command systems.



The first successful test flight of the JB-2 took place at Eglin Field in October 1944.

To put the JB-2 into wider production, the Ford Motor Company was tasked with building the pulsejet engine while Republic Aviation continued to work on the airframe. Manufacturing was contracted to Willys Overland. An updated guidance system was developed by the Monsato Company.

The intended production target of the JB-2 was 75,000, but ultimately closer to 1,391 were constructed and delivered to all branches of the US military beginning in January 1945. The US Navy shipped some of the finished JB-2s to the Pacific theatre in preparation for a planned invasion of Japan under Operation Downfall. A specialist aerial unit was also formed to launch JB-2s from their planes against targets in Japan and Germany.

The JB-2 missile. Visually, it is difficult to distinguish it from the V-1.

However, the JB-2 was hurried into deployment in part due to the continuing disputes between the land and air components of the US Army over who would have authority over the guided weapons program.



Some military commanders were also hesitant to take delivery of the JB-2, fearing it would impact on the production and shipment of shells and conventional bombs. The US Strategic Air Commander in Europe Carl Spaatz argued for the JB-2 to be used as a supplementary weapon of harassment or terror (similar to how the V-1 had been used) for occasions where bomber aircraft were limited or unable to fly. As the Allied forces continued to liberate occupied countries and enter Germany itself, the number of strategic bombing targets became smaller and the need for a weapon like the JB-2 was reduced.

As a result, the JB-2 was produced in a lesser capacity and remaining units were diverted to the War in the Pacific. As Operation Downfall was conceived, it was planned the JB-2 would be used as part of a combined bombardment with strike aircraft before an amphibious landing.

JB-2 being prepared for launch on its launch rail by technicians.

However, strategists found that launching the JB-2 from land was only feasible once the invasion had started and that it would take too long to convert existing aircraft to launch the missiles from the air.

Japan’s surrender before its downfall brought about the end of the war and meant the JB-2 was never used in active combat despite the extensive research put into producing it. Production was ceased in September 1945.

Nonetheless, the JB-2 went on to provide a useful template for America to pursue further research into more sophisticated guided missile technology with the onset of the Cold War.

Post-war usage

After the war, Eglin Field initially remained the principal testing site for the JB-2 with military experiments using completed airframes to test the capabilities of newly developed guidance systems.

The end of the war and the decentralization of US military branches also provided the engineers more time to develop and experiment with different methods of launching and guiding the JB-2. Initially, the JB-2 continued to be propelled into the sky using a ramp before the US Navy converted a submarine, the USS Cusk, to transport and perform a seaborne launch of a JB-2.

This was carried out from the Cusk in January 1948 with the guidance being controlled by radio from another submarine, the USS Carbonero.

A JB-2 launch off US submarine USS Cusk.

The launch proved a success and marked the first time that a guided missile had been launched from a submarine. As a result, conventional or atomic warheads launched from submarines at a distant target was now known to be possible.

The US Navy continued its launch experiments with the JB-2 until 1953, when it was found many of the older JB-2 models were suffering reliability issues with increasing age and that new research technology could not be perfected any further within the JB-2’s existing design.

Meanwhile, the United States Air Force (USAF) continued tests using the JB-2 to research remote controlled guidance and the further development of surface-to-air and air-to-air missiles at Holloman Air Force Base. In April 1948, the JB-2 program was relaunched as Project EO-727-12 at Holloman with the intention of developing guidance, tracking and seeking systems.

B-17 carrying two JB-2 missiles under its wings.

In January 1949, the USAF successfully created a remote guidance and control system that could fly and land the JB-2 from the ground or another aircraft. Back at Eglin, the USAF also experimented with perfecting launches from the air by firing JB-2s from a B-36 Peacemaker bomber.

By the end of the 1940s, the JB-2 was mostly used as a flying target for the development of new infrared aerial gunsights before it was withdrawn from service and further development was cancelled by January 1949.

Fate

Despite never being used in combat, the JB-2 had a profound impact on the development of tactical guided weapon and rocket technology which would come to define the arms and space race during the Cold War.

Although designed through careful copying of the V-1, American engineers continued to innovate on the existing design to perfect more modern guidance systems to improve the missile’s effectiveness.

The JB-2 would also provide the basis for the Martin MGM-1 Matador; America’s first operational cruise missile which was designed to carry a nuclear warhead.