FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1937
1937 - 0394.PDF
154 FLIGHT. FEBRUARY II, 1937. STARTLING ENGINE CLAIMS Revolutionary But Simple Principles in a New Unit Being Developed for Aero Work WHEN ihf inventor claims for a new internal-com bustion unit that it will run with absolute reliability at .peeds varying between idling and 11,000 r.p.m., that it will develop 100 b.h.p. per litre, that it will accept commr rcud spirit on a 12 : 1 compression ratio, that it consumes OPly -32lb. per h.p., and that under these con ditions it is quite satisfied with ordinary "pot" sparking plugs, one's curiosity is aroused. Yet such statements have been passing round in Lancashire for some time "now. They have been applied to an engine designed by Mr. F. M. Aspin, and a company has been formed to carry on development work, the concern being F. ML Aspin, Ltd. Egyptian Mills, Elton, Bury. So fai the experimental work has been done on motor cycle engines but an aircraft engine is now being made, al though as yet it is not permissible to reveal the details of constructing So far as the motor cvcle engine goes a general description may indicace the possibilities. The single-cylinder unit is of alloy construction throughout, with a nitrogen-hardened liner in the barrel Including the i81b. flywheels necessitated by the 13 to 1 compression ratio, the weight is only 481b. and the power developed is over 25 b.h.p. at 11,000 r.p.m., so that a ratio of about 2 lb. per h.p. is obtained and the fuel consumption is 0.32 to 0.35 lb. per h.p., using B.P. Ethyl. Ordinary commercial grade spirit can be used without difficulty. High Thermal Efficiency The features upon which the high thermal efficiency are based are the complete scavenging of the exhaust gases and the controlled turbulence of the charge. The high thermal efficiency and the uniform heating of the cylinder interior per mit high compression ratios to be used without introducing insuperable cooling problems. Externally there are no moving parts, all the intake and exhaust controlling mechanism being completely enclosed within the cylinder barrel and head and having no adjust ments apart from its own inherent compensations for wear and heat. Tfee mechanism, it is stated, absorbs no greater mechanical power than a magneto, and will last at least as long as tne crankshaft bearing, i.e., the life of the engine. This photograph of the cylinder of the experi mental Aspin engine suggests a Diesel con version at first glance, but gives no hint of the system that is employed in actual fact. The aero engine, which is now being built, is a compact unit of 1,731 c.c. (83 x 80 mm.) with four cylinders, op posed in pairs, with a three-throw crankshaft. It is to develop 80-100 b.h.p with the rather startling normal r.p.m. of 5,000, and a maximum of 8,000 r.p.m. The weight, including ;i 2 ' 1 reduction gear, will be approximately 100 lb. so that the weight-power ratio is to be in the region of 0.81 lb./h.p. ; this could be improved by increasing the speed if required, as the engine is quite capable of turning at a much higher rate than the 5,0008,000 r.p.m. range adopted. This, however, would raise the difficulty that the thrust horse-power would be very low at take-off; a 4 : 1 reduction would seem to be nearer the mark. Elektron crankcase, light alloy barrels and heads, and special alloy connecting rods are' being used. The air-coolei] cylinders are cast in pairs and are of streamlined form. A single carburetter with a rotary vane type of mixture dis tributor is to be fitted. The unrestricted inlet port is i| sq, in., and the exhaust port 2 sq. in. in area. Although it is not possible to give details of the internal construction, Flight has been permitted to examine the draw ings and component parts, and it is possible to say that the design is of that exceedingly simple order that prompts the query, "why did nobody do it that way before?" LONDON'S AIR DEFENCE THE chance of defeating an air attack on London is a subject much discussed in these days in all circles, dnd consequently a large number of members was present at the Royal United Service Institution on Wednesday, February 3, when Brevet Lieut.-Col. K. M. Loch, M.C., of the Royal Artillery, read a paper on " Anti-Aircraft Defence." Air Chief Marsh Sir Hugh Dowding, K.C.B., C.M.G., was in the chair Speaking to an audience composed mostly of officers, active and retired, of the Navy and Army, the lec turer confined himself to what might be called the ABC of the subject. He said that there were three forms of air attack which the enemy might make (1) on the morale of the popu lation. This would only need random bombing, and its effect would depend on whether the population was or was not trained in methods of protection. (2) On food supplies, which called for more accurate tombing. The remedy was the pro vision of alternative routes. (3) On military objectives and industries, which, the lecturer said, wis not the direct road to victory in giving quick results. The defence, he said, had to decide whether it was defending morale or some other objective. Active defence meant destroying the raiders and employing the counter-offensive, and passive defence meant making it more difficult for the bombing to be effective. This implied dispersion in some cases, and generally training the population in avoiding the results of the bombing. Active defence consisted of fighter aircraft, guns, search lights, and A.A. machine guns. As an R.A. officer, the lecturer's remarks on the guns were most interesting. After considering all circumstances, he gave it as his opinion that the guns would take a definite toll of the raiders. They should be on mobile mountings, in order to spring a surprise on the enemy. He said that they had a very good predictor, which would make fire effective if the raiders flew on a straight and level course. They had to do that, he said, when engaged in bombing and when keeping formation. A.A. machine guns should have a rapid rate of fire, ami should discharge a x| lb. shell. They were for dealing with low-flying bombers, and should be so disposed as to give an easy shot at dive bombers. As in duck shooting, he said, shots would sometimes be easy and sometimes difficult. Searchlights needed high skill in the crews. The beams should not wander over the sky in search of raiders, but should shoot straight up at them. He said with emphasis that he believed the Territorials would do well in working the guns and searchlights. When questioned about concrete bomb shelters, the lecturer asked the chairman to reply. Sir Hugh Dowdiag said that great thickness of concrete was only necessary against armour- piercing or semi-armour-piercing bombs. These were heavy and expensive and sacrificed explosive weight to weight of casing. They were only suitable for aiming at special targets, and for general purposes were less effective than ordinary air bombs. Great thicknesses of concrete over shelters, therefore, seemed an extravagant luxury. Piston-ring Progress THE foundry of Hepworth and Grandage, Ltd., of Bradford, is being doubled in size as soon as possible in order to deal with the increasing demand for Hepolite products in general. A new bay has lately been added to the single cast ring shops.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
