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Aviation History
1940
1940 - 1974.PDF
JULY II, 1940 TROOP-CARRYING GLIDERS Their Technical Possibilities : Silent Approach : Gathering in Norway ? THE German war machine has sprung some surprises,not only in new weapons of war but in new uses ofexisting weapons. The co-ordination of tank and aircraft attack was a new method, while the magnetic mine and the parachute were new weapons. The parachute was not new in the sense that we had not heard of it Defcre. We had—but we scorned it. "They will all be dead before thev are on the ground," we said. And we would have been right, but for the combination of the parachute with that oldest of '' weapons'' of war, the enemy within the gates. Calling it the Fifth Column does not make it a new development, but the way it works is new. We are now aware of these weapons—let us hope our tactical people have worked out the necessary means of countering them—but are we fully aware of all other possi- bilities, not merely the probabilities? If Germany invades this country, what are all the possi- bilities, even the remote ones, for the transport of troops? (Here let it be said that thought should also be given to what will be regarded by most people as the remotest of all possibilities: that Hitler will not order an attempt at invasion before this winter, but will instead attempt to blockade us.) The Towed Qlider Troops can be brought to this country on the sea, under the sea and over the sea. The Navy must deal with those on the sea in surface ships. If Germany decides to use submarines for the transport of a few specially valu- able men, it is again the Navy's job and that of coastal defence (Army and Air Force). (If any reader feels scorn- ful of the chance of a submarine landing troops unob- served, has he forgotten that a submarine got in—and got out of—Scapa Flow and sank a battleship? But let us now look at the possibilities of troop trans- port over the sea, the troops by air. The troops who will descend by parachute we know of. Their job will include the seizure of at least one aerodrome. And we know the technique of carrying troops in troop carriers such as the Junkers JU52, Ju86 and the four-engined Jugo. Such air- craft can only land on aerodromes. But what of the towed glider? Is this another secret weapon? Let us examine its potentialities. It might be possible for each power aircraft to tow one ghder carrying about 10 soldiers complete with ordinary equipment. Per- haps more than one could be towed, but the chances of accident involving the whole train would be greatly in- creased if more than one glider were on tow. The modern monoplane with retractable undercarriage has a lift/drag ratio at cruising of about 9 or 10. But the outmoded JU52, with corrugated metal skin and non- retracting undercarriage and bad fuselage shape would be more like 6. With gross loaded weight of 22,000 lb. its drag is then about 3,700 lb. A glider to carry 10 troops could be designed to have a very high disposable load. With a landing speed of 30 m.p.h only a skid undercarriage would be needed. There would be no engine, no fuel or oil and no tanks. Each soldier would weigh about 160 lb. and his equip- ment another 90 lb.. making 250 lb. in all, and 2,500 lb. for the ten. In terms of its gross loaded weight, the weight of the glider would be made up as follows: — Fuselage and controls . . . . . . 17 per cent. Wing . . . . .. . . 16 ,, Skid undercarriage .. .. .. 2 ,, Tail unit . . . . .. .. .. 2 ,, Total structure weight . . Disposable load Gross loaded weight 37 per cent. -. 63 ,, ., . . 100 per cent. Using the figure of 60 per cent, for disposable load, gross loaded weight is therefore 4,200 lb. L/D ratio should be at least 10, as the design could be made very clean, although the fuselage would be rather fat to house the troops and the wing rather large to give a landing speed of only 30 m.p.h. Drag is then 420 lb. Total drag of the combination is 4,120 lb., an increase of only 11.4 per cent, over the drag of the JU52. Allow- ing for some reduction in airscrew efficiency (they would not be constant-speed), the cruising speed would only be reduced from about 140 to 120 m.p.h. by the glider. The outstanding advantage of transporting troops by towed glider (as well as in the troop carrier itself) is that the number is increased merely by a small reduction of speed. With 20 in the troop carrier and 10 in the glider, the increase in number is 50 per cent., a worth-while figure. The technique would probably be to take-off before dawn and cross the sea, taking every advantage of darkness, weather or artificial fog (if there is such a thing). Gain- ing as much height as possible (probably not more than 10,000ft. would be possible for a JU52 with glider), the glider would be cast off about 10 miles before reaching the coast. It could then cross the coastline, even against some adverse wind, as in still air it could glide 19 miles. Its approach would be silent, and a diversion would have already been made for it by the troop carriers which had gone on ahead after casting off. The glider's chances of coming in to land before being shot by fighters cannot be dismissed as negligible, even though they would be, of course, completely at the mercy of a fighter, being unarmed and unarmoured. The whole thing hangs on the relative number of gliders (and other aircraft) and fighters. It will perhaps be noticed that the word '' shot'' was used, and not "shot down." With an aircraft without engines or fuel, the fighter pilofs bullets might not shoot it down, even though they hit it. It would probably still glide down imperturbably, unless the control cables were cut, the pilot dead or the tail shot off. For Qeneral Confusion The gliders are, of course, " dead meat " to fighters, but that will not prevent them being used if Hitler thinks they will aid his invasion. A wave of infantry is '' dead meat" to a withering machine-gun fire, but we have all heard stories of how wave on wave of troops have come on. Only unthinking people accuse German fighting men of not being brave. They may be cruel, but that is an- other story. The low landing speed of the glider would be very useful as it could get down almost anywhere, despite obstructions in fields. A small proportion of troops might be hurt in landing, but it would only be very small if the landing speed were 30 m.p.h. The pilots need not be power pilots; troops specially trained just up to the standard required to land a glider would be adequate for this particular purpose. The sort of troops that might be sent across the sea in such a manner would not be those intended for the seiz- ing of any particular objective, as it would be rather un- certain where they would land once they had been cast off. They would be just " general confusion " troops who would join up with the main bodies as soon as possible. Since writing this article a report has been released that the Germans are assembling a fleet of gliders at Vernes, near Trondhjem, on the Norwegian coast. If such a report can be relied upon, it is difficult to understand why gliders are being collected together at a point so far north of and so distant from the- British Isles, the latitude of whose northernmost part, the Orkneys, is 59 degrees. The lati- tude of Trondhjem is 63.26, not much south of Iceland, which is at 64.40 north.
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