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Aviation History
1954
1954 - 1973.PDF
24 FLIGHT, 2 July 1954 LEDUC RAMJET INTERCEPTERS Some Notes on Courageous French Private-Enterprise Developments IT was in 1929 that M. Rene Leduc first began the development of the propulsive system which as now resulted in the Leduc 021 ramjet aircraft. From that year onwards, and even, on a limited scale, through the war years, he has continued development and testing of the concept. First result of the programme, which was carried on with only cursory official interest, was the Leduc 010, which flew soon after the war; many of its components had been constructed before the war, but in 1940 the German advance forced the designer to move to the South of France, and later that year to hide his equipment in farm houses near Toulouse for the duration. The 010 was developed into the 016; both were research vehicles of comparatively low performance, air- launched from a carrier mounted on a Languedoc transport. The most recent model to have flown is the 021. This is approximately twice as large as the 016 and correspondingly more powerful. It is, in fact, more a fighter prototype than an aerodynamic research vehicle, and is reportedly capable of carrying machine guns or cannon without major alterations. Its performance, although still subsonic, is in many ways spectacular, including a sea-level rate of climb of 39,420 ft/min. It has a span of 38ft lin, length 41ft lin, height 9ft and wing area of 238 sq ft. It weighs 8,350 lb empty and 13,200 lb all up. Limiting speed is 0.85 Mach, ceiling 65,000ft and endurance varies according to altitude between 15 min and 1 hr. When first launched from its Languedoc carrier, the ramjet was lit before release while diving at 240 m.p.h. More recently the 021 has been released cold and then dived, lit and flown under power for some 20 minutes. Then all the remaining fuel is jettisoned and the machine landed dead stick. Since virtually the whole fuselage is taken up by the ramjet and ancillaries, fuel is carried between the wing spars, in integral tanks, and in two wing tip tanks. Though this may amount to some 400 gallons, it is not sufficient to give a really useful operational endurance. The 021 is a post-war aircraft; by contrast the 010 was first designed in 1937 although it did not fly till after the war. The 010 weighs 6,600 lb all up with a wing area of 173 sq ft, but is capable of 0.84 Mach. It will, moreover, maintain this speed in the climb with a rate of climb of 7,800 ft/min at 29,000ft. The 021's rate of climb, in comparison, falls off to 2,900 ft/min at 49,000ft. The design of the two aircraft is interesting. Because they came before their time, and because of a lack of official interest and backing, many of the problems associated with high-altitude and high-speed flight had to be solved by M. Leduc before they even arose for other manufacturers. He had to design his own monotrace undercarriage, fuel pump and controls, powered flight controls, pressurized cabin and pilot- escape mechanism. Due to the considerable fuel-flow to be accepted, a turbine-driven fuel pump was built and run in 1940, and the power controls originally designed have been taken up for development by the Societe Jacottet. His cabins have all been completely sealed, air-conditioned, pressurized and jettisonable. The undercarriage consists of a tandem two-wheel retracting main unit, assisted by a tailwheel and two outrigger wheels mounted in keel fairings under the wing-tip tanks. Whereas the cabin of the 010 was partly buried in the main tube, that of the 021 is completely free of the main fuselage and, moreover, almost completely cased in transparent material, affording the pilot a vastly improved view. The whole plastic cone slides forward on its supporting shaft to allow access; only one circular joint requires to be sealed. Parachutes to lower the cabin after jettisoning are stowed behind the pilot. The 021's fuel pumps and generators are driven by a Turbomeca Artouste shaft-drive turbine mounted behind the cabin. Fuel is sprayed into the tube through seven banks of three rows of burners, with a separate fuel supply for each bank. Thus, the banks can be lit progressively, according to speed or other The view of the 021 (top) may be compared with that of the 016. The pilot's cabin is completely clear of the main tube. The021 has approxi mately twice the power of the 016. The Leduc 021, seen head-on, shoe's the concentric pilot's cabin, air intake and banks of fuel injectors and their flame holders. Daylight can be seen through the fuselage. Sesn soon after the war, the Leduc 016, immediately above, is mounted on fie Languedoc and being prepared for flight. Three Languedocs have be*n modified as carriers. factors. The fuel pump has a capacity of 126 gal/min. The first ostensibly operational fighter version will be the Lee ic 022. This will be capable of Mach 2 at altitude, and will hav a S.N.E.C.M.A. Atar of unspecified mark mounted behind the cai in (inside the ramjet) to permit the machine to take-off under :ts own power. M. Leduc has so far released no details of t us machine and, though it is probably under construction, it is ' ot known when it will first take the air. The 021 is at present being test flown at the summer he u- quarters of the Centre d'Essais en Vol (French Boscombe Do' n) at Istres, near Marseille. The three modified Langue oc carriers are there, together with the special gantry for hois ng the ramjet up onto the carrier. An official colour film has so been made of some of the flights and privately shown in Fra ce.
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