FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1922
1922 - 0646.PDF
NOVEMBER 2, 1922 CORRESPONDENCE The Editor does not hold himself responsible for opinions expressed by correspondents. The names and addresses of the writers, not necessarily for publication, must in all cases accompany letters intended for insertion in these columns. SCRAP THE LOT [2(162] 1 read with interest Prof. Bairstow's lecture on Prof. Langley's work, and am glad to see he has brought forward the case against the British administrative system of scientific control. I trust the matter will be pressed home until research workers get justice and fair play. When one has had experience of the system operating, it is easily under stood why Britain lags behind in advanced design. Why should men who have specialised on a particular branch of research work be left to the tender mercies of some officials whose knowledge in many cases is only superficial, and limited to a subject which is common property. At the present stage of agitation for reform, and as far as some twenty years' experience with official experts is concerned, I think the following may be interesting to some FLIGHT readers. , In 1902 1 patented the first heavier-than-air machine fitted with slotted planes, the angle of incidence of which could be varied by the aviator in flight for fast or slow flying. This design won the first prize presented by the President of the Aeronautical Society, but was turned down by the official experts. In 1907 I designed, built and flew the first two all- metal aeroplanes at the Daily Mail Competition at the Alexandra Palace. The machines had no struts or wire bracing, embodied the tractor propeller hemispherical entry, enclosed streamline body with non-lifting tail and hinged elevating flaps. (Bleriot, at a much later date, flew with a lifting- tail, which was afterwards found to be wrong in prac tice.) The late Hon. Charles Rolls, in describing machines in the Daily Mail at that date, said my system of construction would be extensively used in the future. The Farnborough experts thought otherwise, and turned it down, preferring to play about with bamboo poles, bits of string and canvas. Prof. Junker developed the idea in 1918, followed by Short Brothers in 1920. This year I submitted to the Research Department of the Air Ministry a new type of multo-ported oscillating split ring valve gear for aero engines, the chief feature of which is that the ports in the valve register alternately with the inlet and exhaust passages, and the design of the cylinder head is such that paraffin can be effectively vaporised without heating the induction pipes. The back face of the valve is both water and air cooled. The interior of the valve is wholly swept by the cool gases on the induction stroke ; this means that the valve and combustion chamber can be kept moderately cool, and introduces the possibility of higher compression with increased efficiency without fear of pre-ignition. It has large free ports, and is positively operated by standard practice cam gear, has few working parts, light, simple, silent and accessible. The Air Ministry's engine experts graciously admitted that many of my claims were justified, but said they had no money for this type of experiment. What is more important in an aero engine than safety from fire, and a reliable valve which once it is installed like a sleeve valve, requires no further adjustment or grinding. They concluded their remarks by judging the merits of the design from the performance of a poppet valve aero engine (presumably because they had had no experience with any other type of valve gears), overlooking the fact that the working conditions are entirely different, and turned the design down on the following objections :— Heat and lubrication, and pressure on the valve. (1) Heat, because they find the oil gets burnt in an aero engine by the hot piston, which is neither water nor air cooled on its driving face. They concluded the oil behind my valve must also get burnt, although it is wholly water and air cooled on its back face, and wholly cooled internally at each suction stroke. (2) At the point of exhaust opening the pressure in the com bustion chamber would be nearly 50 lbs. per square inch. It would be realised, the efore,ithat the friction against which the valve has to be moved would be very large and the danger of seizure ever present. Answer : I do not intend to open or move the valve when there is a pressure of 50 lbs. per square inch in the combustion chamber. This to my mind is a wicked waste of energy, and can be avoided with this valve gear. I know it is done in high-speed aero engines, but why ? Because with spring-returned valves the actual closing is unknown, and the valve heads have a baffling effect on the gases. In my long-stroke, high-compression positively operated large free port engine I can afford to keep the valve, Stationary, opening late when the pressure drops below 20 lbs. which it will do in my engine, because of higher compression ratio and long stroke; also keep the inlet valve open late, ' because J know definitely when the exhaust and inlet ports are closed. Oil grooves are cut in the back face of the valve ; the suction and pressure strokes insure that there will always be a film of oil pulsating between the valve and cylinder head. In conclusion, is it fair to compare an engine with a positive timing against one with a partially theoretical one ? Can a valve which is perfectly cooled get as hot as a piston, which is only cooled where there is the least heat ? Can a valve which is split and perfectly lubricated seize in its bearing ? I leave it to FLIGHT readers to judge. I don't blame the gentlemen of Kingsway for the attitude they take up. It is not their fault; it is the system operating. They are not sure of their ground off the beaten track, so in order that they should make no mistakes, they turn advanced ideas down, fervently hoping that nothing more will be heard of them while they are in office. WILLIAM COCHRANE PILOT BALLOONS AND GLIDING [2063] Whilst investigating the structure of the atmo sphere by observing the rate of ascent of pilot balloons at Pyrton Hill in 1910-n, Mr. J. S. Dines observed a peculiarity in the movement of the balloons which might possibly be of great assistance to motorless aviators. It was found that a balloon when released from the ground always ascended at a greater velocity than that determined from its physical properties for its ascent in still air. The excess velocity was found to decrease as the balloon gained height. These facts have also been noted by independent observers in France and Germany. The explanation offered by Mr. Dines was that the balloons when near the ground naturally find their way into ascending currents, since these must be continually fed from bejow. Use can be made of this in gliding experiments by releasing a number of balloons from such a place that they will drift towards the pilot's starting-point. By gliding towards any balloon the pilot would greatly increase his chance of finding a region of ascending air. To obtain the best results it would be necessary to use "* balloons with a negligible rate of ascent in still air. The chief difficulty of course, would be in spotting the balloons, but out of a large number it should be possible to see two or three. ALAN SMITH SOARING FLIGHT. [2064] On October 16 I saw the fulfilment of an old, old dream. Twelve years ago, while convalescing at St. Leonards, the seagulls gave a gliding exhibition for my special benefit, and I described the flight of those gulls and how they could be copied by men on gliders if they had the necessary skill. I had not realised how soaring could be carried on for miles along a range of hills until those gulls supplied the key. The following extract from The Field of January 15, 1910, may be of interest at the present time :— . The seagulls at St. Leonards-on-Sea have since enlightened me by demonstrating without question the possi bility of soaring flight under certain conditions of wind, when a glider once launched might be flown for perhaps 10 miles in one direction and back again to the starting point. There was a south wind blowing directly on to the sea front and in order to pass this barrier the wind had to rise in a huge wave over the houses and the hills behind. In similar conditions I have often seen these birds sitting on the wave with their heads towards the wind, but on this occasion a number (per haps a hundred) of gulls were soaring without moving their wings and yet travelling from east to west. The birds flew in detachments of ten to fifteen, and this in somewhat open order, so that they were spread over a considerat le portion of the wave. It was very noticeable that those which flew lowest were most affected by eddies, whilst those soaring at about 300 ft. had fewer difficulties in advancing. Instead of the birds being head to wind as they would be if floating only, they were turned to an angle of about 45° to the west, thus pointing to the fact that half the supporting power of the wave was being used by them to travel from east to west, the remaining margin being sufficient for their support at a constant altitude. I watched these birds travelling to the west until they arrived at the end of the sea front, where both houses and hills terminate, and then these living gliders simply turned their tails and heads to an angle of 45° in the opposite direction, and came sailing back over my head towards Hastings. Now, none of these birds did anything that an expert on a glider could not do, viz., balance and 646
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
