Hajile was one of a number of highly experimental projects, including the Hedgehog and Panjandrum, that were developed by the British Admiralty's Directorate of Miscellaneous Weapons Development (DMWD) during the final years of World War II. The project was initiated by a request from the Army for a method of dropping heavy equipment and vehicles from aircraft at high speed, retaining the materiel's terminal velocity for as long as possible in order to minimise drift and damage from anti-aircraft batteries. It was further required that the materiel suffer only minimal or no damage from landing, and once dropped be ready to deploy within minutes. Hedgehog anti-submarine weapon An anti-submarine weapon developed by the Royal Navy during World War II, the Hedgehog was deployed on convoy escort warships such as destroyers to supplement the depth charge. ... Panjandrum at Westward Ho!, Devon Panjandrum, or The Great Panjandrum was one of a number of highly experimental projects, including the Hedgehog, that were developed by the Royal Navys Department of Miscellaneous Weapons Development in the final years of World War II. The DMWD had been asked to come... Old Admiralty House, Whitehall, London, Thomas Ripley, architect, 1723-26, was not admired by his contemporaries and earned him some scathing couplets from Alexander Pope The Admiralty was historically the authority in the United Kingdom responsible for the command of the Royal Navy. ... This article is becoming very long. ... The British Army is the land armed forces branch of the British Armed Forces. ... Materiel (from the French for material) is the equipment and supplies in Military and commercial supply chain management. ... The terminal velocity of an object falling towards the ground, in non-vacuum, is the speed at which the gravitational force pulling it downwards is equal and opposite to the atmospheric drag (also called air resistance) pushing it upwards. ... American troops man an anti-aircraft gun near the Algerian coastline in 1943 Anti-aircraft warfare, or air defense, is any method of engaging military aircraft in combat from the ground. ...

The high falling speed ruled out parachutes, so the DMWD came up with the idea of loading the drops onto a platform surrounded with cordite rockets. These would fire at the last instant to decelerate the materiel to a safe landing speed. The initial test produced the project's codename; as the rockets' exhaust engulfed the apparatus in a plume of smoke and fire, an attending officer remarked "Look at it! It's Elijah in reverse", referring to the biblical prophet's ascension to Heaven in a similar manner. The Apollo 15 capsule landed safely despite a parachute failure. ... Cordite is a particular family of smokeless propellants made by combining two high explosives: nitrocellulose and nitroglycerin, i. ... A Redstone rocket, part of the Mercury program The traditional definition of a rocket is a vehicle, missile or aircraft which obtains thrust by the reaction to the ejection of fast moving fluid from within a rocket engine. ... Elijah in the wilderness, by Washington Allston Elijah (אֱלִיָּהוּ Whose/my God is the Lord, Standard Hebrew Eliyyáhu, Tiberian Hebrew ʾĔliyyāhû), also Elias (NT Greek Hλίας), Ilia (NT Bulgarian Илия), Ilie (NT Romanian), is a prophet of the Hebrew Bible or Old Testament. ...

Testing

Initial tests

Once testing began, a number of problems became apparant. The most immediate was that of how to get the rockets to fire at exactly the right instant. Too early and the platform would pick up enough speed again to cause damage to the load. Too late and the deceleration would be ineffective. The solution settled upon was a plumb-bob, which would dangle below the platform and activate the rockets when it hit the ground. However, the implementation of this idea was complicated by the fact that the weight of the plumb-bob would have to be carefully calibrated, heavy enough not to be blown back into the underside of the platform by the extreme upward winds during the fall, yet still sensitive enough to react immediately on hitting "fuzzy" terrain such as heather or long grass. Plumb Bob A plumb-bob is a weight with a pointed tip on the bottom that is suspended from a string and used as a reference line that is perpendicular to the ground. ...

A prototype device was constructed for use over water, since the relatively flat and smooth surface of the water would work as an idealised ground-target and with luck the rig wouldn't sustain any damage from the fall. The weight for the plumb-bob was worked out experimentally, and so the first full-scale tests began. A large concrete block was strapped to the top of the Hajile platform, and the rig loaded into a Lancaster bomber. After a number of attempts to drop the device ended with hits too far from shore to capture on film, the bomber's crew were instructed to aim as close to the testing facility as possible from a height of 2000 ft. Gerald Pawle, a member of the DMWD at the time, recalls: Pouring a concrete floor for a commercial building, (slab-on-grade) Installing rebar in a floor slab during a concrete pour In construction, concrete is a composite building material made from the combination of aggregate and a cement binder. ... The Avro Lancaster was a four-engine World War II bomber aircraft made initially by Avro for the Royal Air Force (RAF). ... This article is about a foot as a unit of length. ...

"As [Hajile] came screaming through the air the watchers on the pier gazed open-mouthed. Then, suddenly realizing that it was going to score a direct hit, every one started running for dear life down the long plank roadway. The concrete 'bomb' landed squarely on the roof of D.M.W.D.'s engineering shop. It sheared through a massive steel joist and then demolished the covered way leading to the steamer jetty. Happily there were no casualties, though the Wren cooks preparing lunch a few feet from the wrecked shelter thought the end of the world had come."

On further testing, the initial four-rocket design proved slightly ineffective. The addition of another four rockets spaced evenly around the platform increased the deceleration enough to bring the block to a complete stop a few feet above the water, and Hajile quietly sank beneath the surface rather than thunderously crashing into the water as it had done while using the four-rocket design. The Womens Royal Naval Service (WRNS, popularly known as Wrens) was a non-combat branch of the United Kingdom Royal Navy that recruited women. ...

Refinement

The DMWD attempted to procure a number of jeeps to load onto Hajile for testing the prototype over land, but it proved difficult to convince the Royal Navy to provide working vehicles to jettison from a plane at 2000 ft strapped to an experimental, and potentially explosive, device. Eventually two jeeps were provided by the United States Navy and trials began in earnest. The first test was a spectacular failure, as snowfall on the day dampened the rocket fuses. Since the fuses wouldn't light, the whole rig crashed to the ground slowed only by a small pilot parachute, hitting the ground at around 40 ft/s and causing extensive damage to the jeep. Hajile underwent a further two weeks of tinkering before another test was performed. This time the rockets fired successfully and when the smoke cleared, the jeep was relatively intact — but had ended up upside-down, with the platform's rockets pointed skyward. Jeep is an automobile marque (and registered trademark) of DaimlerChrysler. ... The United States Navy (also known as USN or the U.S. Navy) is the branch of the United States armed forces responsible for conducting naval operations. ...

Further testing showed Hajile to be incredibly unreliable: Rockets on some tests misfired and sent the platform into a spin, while on others the weight of the load was misjudged and the platform shot back up into the air for a distance before crashing back to ground with enough force to tear the fittings apart.

One of the last times the rockets on the rig fired was on the morning of the D-Day landings. Hajile was on the ground surrounded by its crew, when an electrician, unaware the device was live, began to test the wiring — and accidently connected the firing circuit. All eight rockets immediately fired and the platform shot forty feet into the air before lurching sideways and crashing back to earth, injuring a number of the crew and blinding one for several days. Land on Normandy In military parlance, D-Day is a term often used to denote the day on which a combat attack or operation is to be initiated. ...

Aftermath

The testing of Hajile ran on long enough that the device was still not working reliably by the time the war drew to a close, and with no chance to put the project into action, it was shelved. The dissolution of the DMWD following the war led to the shelving becoming permanent. As with many such research projects the details of Hajile were kept secret for many years, and very little interest was aroused once the documents describing the project became public. A recreation of Hajile was attempted for the BBC documentary series "The Secret War" in 1978. The first two tests used insufficient rocket fuel, resulting in the concrete block embedding itself firmly into the ground. On the third and final test the technicians filled the rockets with too much fuel, and the block launched itself several dozen feet back into the air again before plummeting to the ground. The British Broadcasting Corporation, invariably known as the BBC (and also informally known as the Beeb or Auntie) is the largest public broadcasting corporation in the world. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Rocket fuel is a propellant that reacts with an oxidizing agent to produce thrust in a rocket. ...

References

• Pawle, G. The Secret War, White Lion, 1972. ISBN 0-85617-120-4
• Johnson, B. The Secret War, BBC Publications, 1978. ISBN 0-09-920790-7