Fieseler Fi 103. V1

Le pulsoréacteur

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Le Republic JB 2, copie du V 1, sur Wikipedia (en)

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The Republic-Ford JB-2 Loon was a United States copy of the German [Vous devez être inscrit et connecté pour voir ce lien]. Developed in 1944, and planned to be used in the United States invasion of Japan ([Vous devez être inscrit et connecté pour voir ce lien]), the JB-2 was never used in combat.

It was the most successful of the [Vous devez être inscrit et connecté pour voir ce lien] Jet Bomb (JB) projects (JB-1 through JB-10) during [Vous devez être inscrit et connecté pour voir ce lien].

Postwar, the JB-2 played a significant role in the development of more advanced surface-to-surface tactical missile systems such as the [Vous devez être inscrit et connecté pour voir ce lien] and later [Vous devez être inscrit et connecté pour voir ce lien].

Wartime development


The United States had known of the existence of a new German secret weapon since 22 August 1942 when a Danish Naval Officer discovered an early test version of the V-1 that had crashed on the island of Bornholm; in the [Vous devez être inscrit et connecté pour voir ce lien] between [Vous devez être inscrit et connecté pour voir ce lien] and [Vous devez être inscrit et connecté pour voir ce lien].

A photograph and a detailed sketch of the V-1 test unit V83 was sent to Britain.

This led to months of intelligence-gathering and intelligence-sifting which traced the weapon to [Vous devez être inscrit et connecté pour voir ce lien], on Germany's Baltic Coast, the top-secret German missile test and development site.

As more intelligence data was obtained though aerial photography and sources inside Germany, it was decided in 1943 for the United States to develop a jet-powered bomb as well.

The United States Army Air Forces gave [Vous devez être inscrit et connecté pour voir ce lien] a contract in July 1944 to develop the JB-1 (Jet Bomb 1)
turbojet-powered flying bomb under project MX-543.

Northrop designed a flying-wing aircraft with two General Electric B1 turbojets in the center section, and two 900 kg (2000 lb) general purpose bombs in enclosed "bomb containers" in the wing roots.

To test the aerodynamics of the design, one JB-1 was completed as a manned unpowered glider, which was first flown in August 1944.

However, in July 1944, three weeks after German V-1 "Buzz Bombs" first struck England on June 12 and 13, American engineers at [Vous devez être inscrit et connecté pour voir ce lien], fired a working copy of the German [Vous devez être inscrit et connecté pour voir ce lien] pulse-jet engine, "reverse-engineered" from crashed German V-1s that were brought to the United States from England for analysis.

The reverse engineering provided the design of America's first mass-produced guided missile, the JB-2.

By 8 September, the first of thirteen complete JB-2s, reverse engineered from the material received at Wright Field in July was assembled at [Vous devez être inscrit et connecté pour voir ce lien].

The United States JB-2 was different from the German V-1 in only the smallest of dimensions.

The wing span was only 2½ inches wider and the length was extended less than 2 feet (0.61 m).

The difference gave the JB-2 60.7 square feet of wing area versus 55 for the V-1.

This was the first unmanned guided missile in America's arsenal.

The first launch of a JB-2 took place at [Vous devez être inscrit et connecté pour voir ce lien] in Florida on 12 October 1944. In addition to the Eglin group, a detachment of the Special Weapons Branch, Wright Field, Ohio, arrived at[Vous devez être inscrit et connecté pour voir ce lien], [Vous devez être inscrit et connecté pour voir ce lien], in 1944 with the mission of evaluating captured & experimental systems, including the JB-2.

Testing was from a launch structure just south of Wendover's technical site. Parts of crashed V-1s and JB-2s are occasionally found by Wendover Airport personnel.

In December 1944, the first JB-1 was ready for launch.

The missile was launched by a rocket-propelled sled along a 150 m (500 ft) long track, but seconds after release the JB-1 pitched up into a stall and crashed.

This was caused by an incorrectly calculated elevon setting for take-off, but the JB-1 program was subsequently stopped, mainly because the performance and reliability of the GE B1 turbojet engines were far below expectations.

In addition, the cost to produce the Ford copy of the Argus pulse-jet engine of the JB-2 was much less than the GE
turbojets. Subsequently work proceeded on the JB-2 for final development and production.

An initial production order was 1,000 units, with subsequent production of 1,000 per month.

That figure as not anticipated to be attainable until April 1945. Republic had its production lines at capacity for producing [Vous devez être inscrit et connecté pour voir ce lien], so it sub-contracted airframe manufacturing to [Vous devez être inscrit et connecté pour voir ce lien].

[Vous devez être inscrit et connecté pour voir ce lien] built the engine, designated IJ-15-1, which was a copy of the V-1's 900-lb. thrust Argus-Schmidt pulse-jet.

Guidance and flight controls were manufactured by Jack and Heintz Company of [Vous devez être inscrit et connecté pour voir ce lien], and [Vous devez être inscrit et connecté pour voir ce lien] took on the task of designing a better launching system, with Northrop supplying the launch sleds. Production delivery began in January 1945.

An envisioned 75,000 JB-2s were planned for production.

A USAAF launching squadron was formed in anticipation for using the weapons both against [Vous devez être inscrit et connecté pour voir ce lien] and Japan.

However, the end of the European War in May 1945 meant a reduction of the number of JB-2s to be produced, but not the end of the program.

Army commanders in Europe had dismissed it as a weapon against Nazi Germany, as the strategic bombing concept was implemented and by 1945 the number of strategic targets in Germany was becoming limited.

However, the JB-2 was envisioned as a weapon to attack Japan.

A 180-day massive bombardment of the Japanese Home Islands was being planned prior to the amphibious landing "by the most powerful and sustained pre-invasion bombardment of the war".

Included in the assault were the usual naval bombardment and air strikes augmented by rocket-firing aircraft and JB-2s.