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 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.
In July 1944, three weeks after German V-1 "Buzz Bombs" first struck England on 12 and 13 June, American engineers at Wright Field, fired a working copy of the German Argus As 014 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 Republic Aviation. 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. One of the few visible differences between the JB-2 and the V-1 was the shape of the forward pulsejet support pylon — the original V-1 had its support pylon slightly swept back at nearly the same angle on both its leading and trailing edges, while the JB-2's pylon had a vertical leading edge and sharply swept-forward trailing edge. A similar, completely coincidental re-shaping, but with a much broader chord, was used for the same airframe component of the manned Fieseler Fi 103R Reichenberg, original V-1 ordnance development.

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 (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.

An initial production order was 1,000 units, with subsequent production of 1,000 per month. That figure was not anticipated to be attainable until April 1945. Republic had its production lines at capacity for producing P-47 Thunderbolts, so it sub-contracted airframe manufacturing to Willys-Overland. Ford Motor Co built the engine, initially designated IJ-15-1, which was a copy of the V-1's 900-lb. thrust Argus-Schmidt pulse-jet (the Argus As 014), later designated the PJ31. Guidance and flight controls were manufactured by Jack and Heintz Company of Cleveland, Ohio, and Monsanto 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 Nazi Germany 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.

A navalized version, designated KGW-1, was planned to be used against Japan from LSTs (Landing Ship, Tank) as well as escort carriers (CVEs). In addition, launches from PB4Y-2 Privateers were foreseen and techniques developed. The official U.S. Air Force Fact Sheet on the JB-2 states just before the end of the war, an aircraft carrier en route to the Pacific took on a load of JB-2s for possible use in the planned invasion of the Japanese home islands; the name of the carrier has never been identified. In addition, according to one Eglin AFB history, an unidentified USAAF unit in the Philippines was preparing to launch JB-2s against Japan. The war's end led to the cancellation of Operation Downfall and the production of JB-2s was terminated on 15 September. A total of 1,391 units were manufactured.

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.

After the United States Air Force became a fully independent arm of the National Military Establishment 18 September 1947, research continued with the development of unmanned aircraft and pilotless bombers, including the already available JB-2.

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 120 m, two-rail ramp on a 3° earth-filled slope, and a 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.

The 1st Experimental Guided Missiles Group used JB-2s in a series of tests in the late 1940s at Eglin Air Force Base, Florida. In early 1949, the 3200th Proof Test Group tested launching JB-2s from the under the wings of B-36 Peacemaker bombers at Eglin AFB. About a year later, JB-2s were tested as aerial targets for experimental infrared gunsights at Eglin.

The Navy version was featured in the movie The Flying Missile (1951), including submarine launches. The movie shows the missile being launched from a trolley with four JATO bottles.

In the mid-1992, military crews uncovered the well-preserved wreckage of a JB-2 at a site on an Air Force-owned section of Santa Rosa Island. Most crash sites on the barrier island were little more than flaky rust, but after the find, officials were planning further searches


Battle of France 1940

In the winter of 1939 - 40, the Belgian consul-general in Cologne had anticipated the angle of advance that Manstein was planning. Through intelligence reports, they deduced that German forces were concentrating along the Belgian and Luxembourg frontiers. The Belgians were convinced that the Germans would thrust through the hilly and heavily forested Ardennes and to the English Channel with the aim of cutting off the Allied field armies in Belgium and north-eastern France. 

Taistelu Ranskasta

They also anticipated that the Germans would try to land airborne and glider forces behind the Allied lines to break open Belgian fortifications. Such warnings were not heeded by the French or British.

In March 1940, Swiss intelligence detected six or seven Panzer divisions on the German-Luxembourg-Belgian border. More motorised divisions had also been detected in the area. French intelligence were informed through aerial reconnaissance that the Germans were constructing pontoon bridges partially - about halfway - over the Our River on the Luxembourg-German border. 

The French military attaché in the Swiss capital - Bern - warned that the centre of the German assault would come on the Meuse at Sedan, sometime between 8 and 10 May. The report was dated 30 April. These reports had little effect on Gamelin, as did similar reports from neutral sources such as the Vatican, and a French pilot's sighting of a 100-kilometre-long line of German armored vehicles inside Germany to the Luxembourg border.

Germany had mobilised 4,200,000 men of the Heer, 1,000,000 of the Luftwaffe, 180,000 of the Kriegsmarine, and 100,000 of the Waffen-SS. When consideration is made for those in Poland, Denmark and Norway, the Army had 3,000,000 men available for the offensive on 10 May 1940. These manpower reserves were formed into 157 divisions. Of these, 135 were earmarked for the offensive, including 42 reserve divisions.

The German forces in the West in May and June deployed some 2,439 tanks and 7,378 artillery guns, including matériel reserves committed. In 1939–40, 45 percent of the army was at least 40 years old, and 50 percent of all the soldiers had just a few weeks' training. Contrary to what the Blitzkrieg legend suggests, the German Army was far from fully motorised; just 10 percent of their army was motorised in 1940 and could muster only 120,000 vehicles, compared to the 300,000 of the French Army. 
The British had the most enviable contingent of motorised forces. Most of the German logistical tail consisted of horse-drawn vehicles.

Only 50 percent of the German divisions available in 1940 were combat ready, often being more poorly equipped than their equivalents in the British and French Armies, or even as well as the German Army of 1914. In the spring of 1940, the German army was semi-modern. A small number of the best-equipped and "elite divisions were offset by many second and third rate divisions".

Army operational deployment
The German Army was divided into three army groups. Army Group A, commanded by Gerd von Rundstedt, was composed of 45½ divisions, including seven armoured, and was to execute the decisive movement through the Allied defences in the Ardennes. The manoeuvre carried out by the Germans is sometimes referred to as a "Sichelschnitt", the German translation of the phrase "sickle cut" coined by Winston Churchill after the events to describe it, but never the official name of the operation. It involved the participation of three armies (the 4th, 12th and 16th) and had three Panzer corps. 

One, the XV, had been allocated to the 4th Army, but the other two, the XXXXI (Reinhardt) and the XIX (Guderian) were united with the XIV Army Corps of two motorised infantry divisions on a special independent operational level in Panzergruppe Kleist (officially known as XXII Corps).

Army Group B under Fedor von Bock, composed of 29½ divisions including three armoured, was tasked with advancing through the Low Countries and luring the northern units of the Allied armies into a pocket. It consisted of the 6th and 18th Armies. Army Group C, composed of 18 divisions under Wilhelm Ritter von Leeb, was charged with preventing a flanking movement from the east, and with launching small holding attacks against the Maginot Line and the upper Rhine. It consisted of the 1st and 7th Armies.

The real trump card for the Germans was the radio. The Panzers all had radios that allowed voice communication with other units. This enabled German armour to respond rapidly to a constantly changing battlefield situation. It allowed for last-minute changes in tactics and improvisations to be formed far more quickly than the enemy could. Some commanders regarded the ability to communicate to be the primary method of combat. Radio drills were even considered more important than firing accurately. 

Communication allowed German armour to coordinate their formations, bringing them together for a mass firepower effect in the attack or defence. This offset the French advantage in numbers and equipment, which was deployed in "penny-packets" (dispersed as individual support weapons). The French also lacked radios and orders were passed from mouth to mouth. The opposing systems would give the Germans a decisive edge in battle.

The radio network went beyond tank-to-tank commands. The system also permitted a degree of communication between air and ground forces. Attached to Panzer Division were the Fliegerleittruppen (tactical air control troops) which were given wheeled vehicles. There were too few Sd.Kfz. 251 command vehicles to make this a uniform facility throughout the army, but the theory allowed the army in some circumstances to call upon the Luftwaffe units, while either on the ground or airborne, to support an attack that army artillery could not deal with. 

It is said the participants in the dash to the English Channel carried out by Guderian's Corps never had to wait more than 15–20 minutes for the Luftwaffe to appear over a target after they made such calls. 
A specific Junkers Ju 87 group (VIII Fliegerkorps), which was to support the dash to the channel should Army Group A break through in the Ardennes, kept one Ju 87 and one fighter group ready for immediate take-off. On average, they could arrive to support armoured units within 45–75 minutes of orders being issued.

Army tactics
The main tool of the German land forces was combined arms combat. In contrast to the Allies, they relied on highly mobile offensive units, with balanced numbers of well-trained artillery, infantry, engineer and tank formations, all integrated into Panzer divisions. They relied on excellent communication systems which enabled them to break into a position and exploit it before the enemy could react. Panzer divisions could carry out reconnaissance missions, advance to contact, defend and attack vital positions or weak spots. 

Battle of France

Date10 May – 25 June 1940 (1 month and 15 days)
LocationFrance, Low Countries
Decisive German victory, leading to
 Italy (from 10 June)
France France
 United Kingdom
Commanders and leaders
Nazi Germany Walter von Brauchitsch
Nazi Germany Gerd von Rundstedt
Nazi Germany Fedor von Bock
Nazi Germany Wilhelm von Leeb
Nazi Germany Albert Kesselring
Nazi Germany Hugo Sperrle
Italy Umberto di Savoia
France Maurice Gamelin
(until 17 May)
France Alphonse Georges
(until 17 May)
France Maxime Weygand
(from 17 May)
Belgium Leopold III  (POW)
United Kingdom Lord Gort
Netherlands Henri Winkelman
 Władysław Sikorski
Units involved
Germany: 141 divisions
7,378 guns
2,445 tanks
5,638 aircraft
3,350,000 troops
Alps on 20 June
300,000 Italians
Allies: 144 divisions
13,974 guns
3,383 tanks
2,935 aircraft
3,300,000 troops
Alps on 20 June
~150,000 French
Casualties and losses
Germany: 157,621 total casualties(c. 49,000 dead)
1,236 aircraft lost
795 tanks destroyed
Italy: 6,029
Total: 163,650 casualties
360,000 dead or wounded,
1,900,000 captured
2,233 aircraft lost
Total: 360,000 casualties

This ground would then be held by infantry and artillery as pivot points for further attacks. Although their tanks were not designed for tank-versus-tank combat, they could take ground and draw the enemy armour on to the division's anti-tank lines. This conserved the tanks to achieve the next stage of the offensive. The units' logistics were self-contained, allowing for three or four days of combat. The Panzer divisions would be supported by motorised and infantry divisions.

The German Army lacked a formidable heavy combat tank like the French Char B1. In armament and armour, French tanks were the stronger designs and more numerous (although the German vehicles were faster and more mechanically reliable). But while the German Army was outnumbered in artillery and tanks, it possessed some critical advantages over its opponents. The newer German Panzers had a crew of five men: a commander, gunner-aimer, loader, driver and mechanic. 

Having a trained individual for each task allowed each man to dedicate himself to his own mission and it made for a highly efficient combat team. The French had fewer members, with the commander double-tasked with loading the main gun, distracting him from his main duties in observation and tactical deployment. It made for a far less efficient system.

Even within infantry formations, the Germans enjoyed an advantage through the doctrine of Auftragstaktik (Mission command tactics), by which officers were expected to use their initiative to achieve their commanders' intentions, and were given control of the necessary supporting arms.

One of the German strengths was the Luftwaffe. It divided its forces into two groups. In total, 1,815 combat, 487 transport and 50 glider aircraft were deployed to support Army Group B, while a further 3,286 combat aircraft were deployed to support Army Groups A and C. In the first year of the war, the Luftwaffe was the best-trained, most modern and experienced air force in the world.

The main task of German aviation was to provide close support in the form of the dive-bomber and medium bomber. In 1940, the Luftwaffe was a broadly based force with no constricting central doctrine, other than its resources should be used generally to support national strategy. It was flexible and able to carry out operational, tactical and strategic bombing effectively. Flexibility was the Luftwaffe‍ '​s strength in 1940. While Allied air forces in 1940 were tied to the support of the army, the Luftwaffe deployed its resources in a more general, operational way. 

It switched from air superiority missions, to medium-range interdiction, to strategic strikes, to close air support duties depending on the need of the ground forces. In fact, far from it being a dedicated Panzer spearhead arm, less than 15 percent of the Luftwaffe was designed for close support of the army in 1939, as this aspect was not its primary mission.

Anti-aircraft defences
It is generally supposed that the Germans also had a major advantage in anti-aircraft guns, or Flak. In reality, the generally cited figure of 2,600 88 mm heavy Flak guns and 6,700 37 mm and 20 mm light Flak seems to refer to the German armed forces total inventory, including the anti-aircraft defences of Germany's cities and ports and the equipment of training units. (A 9,300-gun Flak component with the field army would have involved more troops than the entire British Expeditionary Force) 

The actual provision of Flak for the invading forces was 85 heavy and 18 light batteries belonging to the Luftwaffe, 48 "companies" of light Flak integral to divisions of the army, and 20 "companies" of light Flak allocated as army troops, that is, as a disposable reserve in the hands of HQs above corps level: altogether about 700 88 mm and 180 37 mm guns manned by Luftwaffe ground units and 816 20 mm guns manned by the army.

France had spent a higher percentage of its GNP from 1918 to 1935 on its military than other great powers, and the government had begun a large rearmament effort in 1936. Due to a declining birthrate during the period of the First World War and Great Depression and the large number of men who died in World War I, France had a severe manpower shortage relative to its total population, which was barely half that of Germany. To compensate, France had mobilised about one-third of the male population between the ages of 20 and 45, bringing the strength of its armed forces to 5,000,000. Only 2,240,000 of these served in army units in the north. The British contributed a total strength of 897,000 men in 1939, rising to 1,650,000 by June 1940. In May, it numbered only 500,000 men, including reserves. Dutch and Belgian manpower reserves amounted to 400,000 and 650,000, respectively.

There were 117 French divisions in total, of which 104 divisions (including 11 in reserve) were for the defence of the north. The British Army contributed 13 divisions, three of which had not been organized when the campaign began. Some 22 Belgian, 10 Dutch and two Polish divisions were also a part of the Allied order of battle. British artillery strength amounted to 1,280 guns. Belgium fielded 1,338 and the Dutch, 656. France had 10,700 pieces. This made a total of around 14,000 artillery pieces, 45 percent more than the Germans. The French army was also more motorised than its opponent, which still relied heavily on horses. Although the Belgians, British and Dutch had barely any armour, the French had a powerful force of 3,254 tanks. The force was both larger and of higher quality than Germany's, as shown by its tactical victory in the Battle of Hannut, the largest tank battle of the campaign.

The French Army was of mixed quality. It had in its order of battle some formidable units, particularly the light and heavy armoured divisions (DCR and DLM), and several professional infantry divisions. However, many divisions were composed of reserve soldiers, above 30 years old, and were ill-equipped. A serious qualitative deficiency was a lack of anti-air artillery, mobile anti-tank artillery and radio communication systems, despite the efforts of Gamelin to produce mobile artillery units. He used telephones and couriers to communicate with the field during the Battle of France; only 0.15 percent of military spending between 1923 and 1939 had been on radios and other communications equipment.

French tactical deployment and the use of mobile units operationally was also inferior to that of the Germans. Tactically, armour was spread thinly along the French line; French infantry divisions were supported by tank battalions of about 100 tanks, which prevented them from being a strong, independent operational force. Making matters worse, only a handful of French tanks in each unit had radios installed, and the radios themselves were often unreliable, thus hampering communication.

French tanks were also very slow in speed in comparison to the Panzers (except for the SOMUA S35), as they were designed as infantry support, enabling German tanks to offset their disadvantages by out-manoeuvering the French on the battlefield. In 1940, French military theoreticians still considered tanks as infantry support. As a consequence, at various points in the campaign, the French were not able to react as quickly as German armour.

In operational terms, the French did not seem to give much thought to armoured units as main offensive weapons. Although some military professionals such as Colonel de Gaulle tried during the 1930s to convince French High Command of the necessity to form armoured divisions supported by aviation and infantry, military conservatism prevented these "new ideas" from emerging. 

The French High Command was focused on maintaining broad and continuous fronts as it had in 1914–18. 
The state of training was also unbalanced, with the majority of personnel trained only to man static fortifications. 
Minimal training for mobile actions was carried out between September 1939 and May 1940.