TWENTY-TON AIR LINER.

King Country Chronicle, Volume XXII, Issue 2514, 15 December 1927, Page 3

TWENTY-TON AIR LINER.

ALL-METAL MONOPLANE. EXPERIMENTAL FLIGHTS. * London, November 2. First flights are about to be attempted at an Air Ministry experimental aerodrome of an all-metal passenger-carrying monoplane built by Beardmores, Ltd., after the design of Dr. A. Rohrbach, the wellknown German aeronautical engineer, who designed the giant Zeppeiin-Sta-aken monoplane during the war. The new machine weighs 20 tons, and is as powerful as the British threeengined flying boats which recently took part in the Baltic cruise. Like them it is fitted with three RollsRoyce Condors, each of 700 h.p. So far (writes the aviation correspondent of the Daily Telegraph) the history of very big machines exceeding 15 tons weight, or having more than three engines, has been unfortunate, few of them having survived first experiments. Progress has been hampered by lack of means. The big British flying boats, however, are an undoubted success. They are biplanes, and they also have the advantage of operating from and over water. A FORMIDABLE PROBLEM. The problem of the land machine of the same power and of even greater weight is formidable. The wheels of the new machine are no less than Bft 6in in diameter. The wing from tip to tip measures more than 140 ft. The wing -is an almost pure cantilever, and in its construction members of such great girth have had to be used that it suggests a feat in bridge-building rather than what is usually associated with ai-eoplane dimensions. It looks strong enough even for the very great demands made by a design embodying a monoplane wing of enormous span. The distance of the wing tips from the body of the machine calls for exceptional provision against strain. The history of big monoplanes has not so far been encouraging. The various types used in Continental air traffic have had a number of serious accidents due to structural failure in flight. The difficulty is to provide the necessary strength, without excessive weight, and a compromise has had to be effected in which anything more than a very moderate speed cannot yet be provided for. The biplane system has the advantage of a comparatively -short span and of mutual support between the top and bottom ’planes. Against this advantage the air resistance of the interplane struts is not a serious drawback. Great interest will be taken in the gig new all-metal monoplane now under trial, for it embodies experimental constructional features. Especially will the take-off of such a huge and heavy machine on ernormous wheels will be studied. A Staaken monoplane fitted with four engines in the wings flew in 1919, but its power was no more than about 1000 h.p. and its weight only 8% tons. Its span was about 100 ft. The new machine is so much bigger and heavier that experiment alone can prove the correctness or otherwise of theory.