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Aviation History
1941
1941 - 1241.PDF
MAY 29TH, 1941. 379 ATLANTIC DELIVERIES (Continued) to Britain is not so very mnch shorter than the direst- crossing from Newfoundland. These comparisons are all based on Newfoundland as the starting point, but it must be remembered that a large number of the principal U.S. aircraft manufacturers are situated in California, so that in that case it might pay to fly straight across the continent to, say, Charleston, and then via Bermuda and the Azores. The total distance would then be less, but there would be almost twice as much over-water flying. Taking everything into con- sideration, the direct non-stop route from Newfoundland to Ireland or the west coast of England seems the best*- ijWT'if we continue our criminally weak policy of allowing the Irish to intern any of our aircraft that land on their territory it seems likely that they will get enough American aeroplanes to become a major air power. The advantages of the direct route are that it is the shortest in time and distance, and also provides the least over-water flying. The weather is reasonable except at . certain times of the year, it enables the best advantage to be taken of the prevailing westerly winds and it no- where approaches enemy country. The Weather The non-stop distance from Botwood to Limerick is 2,010 miles. The actual range required of aircraft for the west— to east crossing should not need to be so very much greater than this because the prevailing wind is westerly, and although there are occasional surface winds from the east, it appears that they rarely if ever extend higher than 10,oooft. Thus, although a range of 3,000 miles is desir- able, 2,500 would be enough, having regard to the exigen- cies of war, to justify air delivery. The direct route is liable to storms over the whole of its length, but by flying at 20,000ft. it should be possible to get above them. The relatively low rated altitude of most American engines is a disadvantage in this respectr- 20,000ft. is somewhere near the most economical cruising altitude for a Merlin-engined aircraft, but there are not* at present many American engines rated to the same alti- tude. Thus, any strong winds are almost certain to be tail- winds. In the summer season the winds are gale strength en only 1-2 per cent, of the days, but in winter they occupy 10 per cent., and even more in parts. Fog is fairly com- rjn around Newfoundland, but is mostly low-lying, and JJoould not cause any difficulty. Fog at the British end Is also not uncommon, and makes the provision of alternsu— tive landing grounds necessary for winter operations. Low-lying cloud is also prevalent over most of the route, but with modern equipment and methods of navigation this is not a serious handicap. On the whole it can be said that during the summer months the west to east flight is reasonably safe for any aeroplane capable of flying 2,500 miles, whilst during the winter months flights should be limited to bombers with sufficient crew, equipment, and reserves of fuel to enable wide deviations to avoid bad weather and fog-bound aero- dromes, and adequate de-icing equipment, as fitted to the*. latest American air liners. In discussing his plan for the mass-production of 100,000 high-speed single-engined bombers in the United States, Mr. Pemberton-Billing recently suggested two additional safeguards for air delivery that seem worthy of serious consideration when production reaches really significant proportions. American promises of 500 aeroplanes a day are not to be laughed at, coming from a country that measures its motor car production in tens of millions, and five aeroplanes a day from a hundred plants is not a big order for such resources. Even if we contemplate all-the -year-round deliveries-' there will probably be 30 or so days a year when flights are not advisable, and roughly 30 per cent, of the aircraft are likely to be types that can safely be flown over only in the summer, so that deliveries of 1,000 aeroplanes a day must be budgeted for. It will thus be necessary to get them off at about minute intervals, if they are all to follow the same route, which seems most desirable, as organised rescue arrangements can then be set up. P.-B.'s first proposal is to send off four-engined flying boats in the line, one every hour, so that there is onk** to every 60 machines; then if an engine fails or anything else occurs to force the pilot down on the water it will be the flying boat's duty to alight and pick up the crew. If the sea is running too high to permit this they will have to depend on surface vessels guided by the boat. To this end, it is proposed that 19 armed ships should be anchored across the route at 100-mile intervals, so that there will always be one within about 50 miles or less, which is well within the gliding range of any modern aeroplane flying higher than 15,000 feet. The ships would be provided with-"" fast motor-boats and special lifeboats for heavy seas. Effect on Aircraft Design Assuming that the war is to continue for sufficient time for further new types to be designed and put into pro- duction, the question arises as to whether it will pay to consider the requirements of air delivery in deciding the original specification. Any bomber of a gross weight of more than about 15,000 lb. will automatically have suffi- cient range if its bomb load is replaced by temporary additional tanks, but there is still the question of its per- formance with an engine stopped or under icing conditions:1*' One of the most important developments in this respect is the introduction of so-called "streamline" flaps, <-hich can be used to provide large increases in lift with com- paratively little additional drag. The minimum power required for level flight depends on the value of CD / CL3/», so that high lift flaps are of considerable assistance despite the fact that they may appreciably reduce the L/D. The Youngman flap comes into this category,, and also the Fowler flap already fitted to the Lockheed and Consoli- dated bombers, used in its semi-extended position. The—1 new N.A.C.A. Venetian blind flap is of even greater value and will improve the rate of climb and ceiling of a typical modern aeroplane with one engine stopped by as much as 30 per cent. These flaps have the disadvantage that they do not steepen the glide so much for landing, so that an additional air brake is desirable. Other probable effects of the Atlantic on American design are provision for the easy fitting and removal of safe additional fuel tanks; provision for overload take- offs in deciding undercarriage factors ; fitting of full de- icing equipment (there seems to be a need for a removable de-icer because carrying de-icers all through the summer means, altogether, several hundred tons less explosive delivered on Berlin, which is a serious matter); provision for the temporary removal and storing inside of gun turrets and other projecting military equipment likely seriously to affect the L/D, and consequently the range; provision for fitting additional navigational instruments and equip- ment to such fighter aircraft as are considered suitable for flight delivery; and, finally, the possible provision for** some form of assisted take-off for small aircraft, either as a normal method of launching or for the Atlantic trip only. The Big Bombers Types which would be capable oi flying over with no modification whatsoever are the Boeing B-17, which with full tanks can fly about 3.100 miles non-stop, the cost in fuel and oil being somewhere about £500; the Martin 162
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