The KGW-1 “Loon”
12 FEBRUARY 1947
THE KGW-1 “LOON”
German technology of WWII was envied by the Allies. In the final months of the war, captured German systems began making their way to the US. One such innovation was the V-1 “buzz bomb,” a pulse-jet powered, winged, unmanned cruise missile that Hitler had launched as a terror weapon against London. The V-1 was gyro-stabilized to straight and level flight, and “aimed” by orienting its steam catapult launch ramp on a direct compass bearing to the intended target. It was fueled with 17 minutes of kerosene, enough to reach London from launch sites near Pas-de-Calaise in occupied France. Its fuel would exhaust over London, allowing the 1900# warhead to fall by its own weight. Flying at 400 mph and with a range of 160 miles, the V-1s presented a difficult defensive dilemma. However, one-in-four V-1s failed due to guidance error or manufacturing oversight. And in July 1944, only a month after V-1 attacks began, the US Army recovered such a “dud” that had crashed without exploding.
By November 1944 the Army Air Corps had reverse engineered, manufactured, and test flown a V-1 knock-off at Elgin Air Base in Florida. Designated the JB-2 (“jet bomb”), the Army’s missile mimicked the V-1 in all aspects but two: A radio-controlled guidance system replaced the gyroscope, allowing a remote controller to steer and dive the missile. And, since pulse-jet engines will not engage until the missile reached a speed of 200 mph, solid rocket boosters were attached to the fuselage for jet-assisted take-off, replacing the catapult employed by the Germans. The JB-2 could also be deployed from the belly of a B-17 or Navy PB4Y “Privateer” in a fashion similar to that developed by Hitler’s engineers. Republic Corporation was contracted to build the airframes, while Ford Motor Company built the PJ-31-F-1 pulse-jet engines. As WWII entered its final stages, it was envisioned that up to 75,000 JB-2s would augment Operation “Downfall,” the planned invasion of mainland Japan.
Our Navy had an interest as well. On 17 November 1944 the Bureau of Aeronautics announced testing had begun on the JB-2 for deployment from escort aircraft carriers against surface targets. Victory in the war came before the missile could be deployed. The Navy’s modifications to the guidance system then resulted in a new designation, the KGW-1 “Loon” missile. On this date, a Loon was launched from the deck of the surfaced submarine USS CUSK (SS-348) off Point Magu (after the lengthy process of assembling a launch ramp and mounting a missile thereupon). This first-ever launch of a guided missile from a submarine married the sub’s stealth with missile technology, opening the door for our modern SSBNs.
Watch for more “Today in Naval History” 19 FEB 23
CAPT James Bloom, Ret.
Department of the Navy, Deputy Chief of Naval Operations (Air Warfare). United States Naval Aviation 1910-1980. Washington, DC: GPO, 1981, pp. 138, 163, 167.
Parsch, Andreas. “LVT-N-2.” Directory of U.S. Military Rockets and Missiles. AT: http://www.designation-systems.net/dusrm/app1/ltv-n-2.html, retrieved 14 August 2013.
Phan, Phloyd. “JB-2 Loon: Reverse Engineering and America’s First Practical Cruise Missile.” AT: http://everything2.com/title/jb-2+loon, retrieved 14 August 2013.
“Republic/Ford JB-2 Loon (V-1 Buzz Bomb).” National Museum of the US Air Force factsheet. AT: http://www.nationalmuseum.af.mil/ factsheet/factsheet.asp?id=510, retrieved 14 August 2013.
ADDITIONAL NOTES: In the immediate post-war years, our Navy had several concurrent missile development programs, the Bat, Bumblebee, Dove, Gargoyle, Glomb, Gorgon, Kingfisher, Little Joe and Lark, but on 12 March 1946 the Chief of Naval Operations directed that most of these be scrapped and the resources re-allocated to the Loon. The Loon program continued until March 1950 when it was replaced by the RGM-6 Regulus missile (also launched from a ramp assembled on the deck of a submarine).
