Republic-Ford JB-2

https://en.wikipedia.org/wiki/Republic-Ford_JB-2

The Republic-Ford JB-2, also known as the KGW and LTV-N-2 Loon, was a United
States copy of the German V-1 flying bomb. Developed in 1944, and planned to be
used in the United States invasion of Japan (Operation Downfall), the JB-2 was
never used in combat. It was the most successful of the United States Army Air
Forces Jet Bomb (JB) projects (JB-1 through JB-10) during World War II. Postwar,
the JB-2 played a significant role in the development of more advanced
surface-to-surface tactical missile systems such as the MGM-1 Matador and later
MGM-13 Mace.

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 Baltic Sea between
Germany and Sweden, roughly 120 kilometers (75 miles) northeast of the V-1 test
launch ramp at the Peenemünde Army Research Center, on Germany's Usedom Island.
A photograph and a detailed sketch of the V-1 test unit, the Fieseler Fi 103 V83
(Versuchs-83, the eighty-third prototype airframe) was sent to Britain. This led
to months of intelligence-gathering and intelligence-sifting which traced the
weapon to Peenemünde, on Germany's Baltic Coast, the top-secret German missile
test and development site.

As more intelligence data was obtained through 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 Northrop
Aircraft 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.

With its Ford-produced PJ31 pulsejet powerplant, the JB-2 was one of the first
attempts at a powered cruise missile for potential usage in America's arsenal.
The JB-2 had nothing more advanced than what the Germans had already placed
aboard their V-1 for guidance, while the indigenously-designed, unpowered U.S.
Navy's Bat anti-ship glide bomb already had an active radar homing system in its
nose to locate its intended maritime targets. The first launch of a JB-2 took
place at Eglin Army Air Field in Florida by the 1st Proving Ground Group on 12
October 1944. In addition to the Eglin group, a detachment of the Special
Weapons Branch, Wright Field, Ohio, arrived at Wendover Field, Utah, in 1944
with the mission of evaluating captured and experimental systems, including the
JB-2. Testing was from a launch structure just south of Wendover's technical
site. The launch area is visible in aerial imagery (WikiMiniAtlas 40°41'53?N
114°02'29?W).

Parts of crashed 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.

Type
Cruise missile

Place of origin
United States

Service history


In service
1945–50

Used by
United States Army Air Forces
United States Air Force
United States Navy

Production history

Manufacturer
Republic Aircraft
Willys-Overland
Ford Motor Company

Produced
1944–45

No. built
1,391


The U.S. Army Air Forces continued development of the JB-2 as Project MX-544,
with two versions — one with preset internal guidance and another with radar
control. Several launch platforms were developed, including permanent and
portable ramps, and mobile launching from beneath the wings of Boeing B-17G or
Boeing B-29 bombers, much as the Heinkel He 111H-22 had done late in the war for
the Luftwaffe in offensive air-launches of V-1s against the Allies. Testing
continued from 1944 to 1947 at Eglin to improve launch and guidance.

The U.S. Navy's version, the KGW-1, later redesignated LTV-N-2, was developed to
be carried on the aft deck of submarines in watertight containers. The first
submarine to employ them was USS Cusk (SS-348) which successfully launched its
first Loon on 12 February 1947, off Point Mugu, California. USS Carbonero
(SS-337) was also modified to test Loon.

The USAF Air Materiel Command reactivated the JB-2 as Project EO-727-12 on 23
April 1948, at Holloman AFB, New Mexico, the former Alamogordo Army Air Field.
The JB-2 was used for development of missile guidance control and seeker
systems, testing of telemetering and optical tracking facilities, and as a
target for new surface-to-air and air-to-air missiles (fulfilling the V1's
covername, Flakzielgerät — anti-aircraft target device). The JB-2 project used
the North American Aviation NATIV (North American Test Instrument Vehicle)
Blockhouse and two launch ramps at Holloman: a 400 ft (120 m), two-rail ramp on
a 3° earth-filled slope, and a 40 ft (12 m) trailer ramp. The trailer ramp was
the first step toward a system which would eventually be adapted for the
forthcoming Martin MGM-1 Matador, the first operational surface-to-surface
cruise missile built by the United States. The program at Holloman was
terminated on 10 January 1949 after successful development of a radio guidance
and control system that could control and even skid-land a JB-2 under the
control of an airborne or ground transmitter.

Specifications

Weight
5,000 pounds (2,300 kg)

Length
27 feet 1 inch (8.26 m)

Diameter
34 inches (860 mm)

Warhead
High explosive

Warhead weight
2,000 pounds (910 kg)

Engine
Ford PJ31 pulsejet
660 lbf (2.9 kN)

Wingspan
17 feet 8 inches (5.38 m)

Operational range
150 miles (240 km)

Speed
425 miles per hour (684 km/h)

Guidance system
Radio command

Accuracy
0.25 miles (0.40 km) at 100 miles (160 km)



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