Project didn't fall apart - the HH just arrived too late. It's predecessor the Tetrarch (with which it shared many features) had already proved something of a disappointment. I include my write up Britain produced the Hamilcar, a large glider that could carry either a British Tetrarch or an American M22 Locust light tank in a capacious fuselage slung under a high wing above which was mounted the pilot’s cockpit. Specially modified Halifax bombers did the towing. The Tetrarch had originally been planned before the outbreak of war as a light cruiser tank with a speed of up to 40 mph. It was a good design and had it been available in 1940 to replace the ridiculous Mark IV light tanks with which British mechanised cavalry regiments were equipped it would have been very useful both in France and in the Western desert. It would have been a match for any of the German and Italian light tanks and given most of the medium tanks of the day problems. However it was not available in time and the light tanks were eventually replaced by American Stuart tanks (sometimes known as Honeys). The powers that be then decided to make it Britain’s main airborne tank. By 1943 it was effectively obsolete. Development of the Hamilcar was effectively based around the design of the Tetrarch. The big glider was not without problems. The strength of the restraints for the tank proved to be an issue and one Tetrarch (and three man crew) was lost on the approach to Normandy when the glider pitched downward in an air pocket and the tank broke free and burst through the nose doors to plunge 300 feet into the English channel. There is a photograph showing a Hamilcar that took part in the Rhine crossing in 1945. The glider has clearly landed intact, its nose cargo door is still shut but there is a Tetrarch shaped hole in it where the tank obviously broke its constraints and exited on touchdown. During the early trial flights it was found that the gliding characteristics of the Hamilcar were not as good as had been expected and aircraft were landing short of their target. One aircraft came down in the middle of an army camp and hit the brick end of a large Nissen hut. The wooden glider stopped dead, the pilots' cabin sheared off and came to rest on top of the hut with its occupants shaken but unhurt. The Tetrarch tank broke its restraints and being of heavier and sterner stuff didn't stop. It burst through the end wall and traversed the length of the hut exiiting the other end in a shower of bricks. Amazingly no one was hurt. The Hamilcar played a role in the D Day landings, Arnhem and the Rhine crossing. By this stage in the War the tanks it was designed to carry were too light to have much impact on the European battleground. Another, unexpected, problem emerged; Tetrarchs landed to support the D Day parachutists were rapidly immobilised as their suspensions and drive wheels became entangled and clogged with the numerous parachute lines that littered the drop zone. Of more value than the tanks was the Hamilcar’s ability to carry a couple of 17 pounder anti tank guns with their supporting vehicles. The Hamilcar had an unfortunate tendency to nose over during landing resulting in the destruction of its cargo if this were less sturdy than a tank. A number of much needed 17 pounder anti tank guns were lost on the Arnhem landing ground because of this problem. A further range of armoured fighting vehicles were developed for airborne use, this included the Harry Hopkins a third lightweight tank and the Alecto a miniaturised self propelled anti tank gun. All suffered from being comprehensively out gunned by the tanks they would have had to have faced. None of these vehicles were ready in time to see action. By the time the Harry Hopkins was ready the airborne tank concept had proved ineffective and the war in Europe was over.