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Aviation History
1944
1944 - 0512.PDF
264 FLIGHT MARCH 9TH, 1944 CORRESPONDENCE uses the surrounding air. A rocket in vacuo needs no power to keep going at a steady speed, whereas a jet machine is still going to have air resistance to cope with. The thrust and instantaneous efficiency (i.e., at a particular speed) can be calculated as for a jet machine giving:—for a rocket aircraft, Thrust (leaving out g for " Projet's" benefit) • = M x Discharge Velocity (in Pounduls) „,.,. . 2 , Discharge Velocity Elfioency — where r=-——.—~-x r-2 2 + r * Aircraft Speed Note that Discharge Velocity takes the place of Slip Velocity in my previous letter. So that, in "Projet's" machine-gun analogy, ballets can be going in the same direction as the gun, but still be giving thrust; which is dependent only on Discharge (Muzzle) Velocity and mass of bullets per second. I cannot see any objection to relating velocities and effi ciencies to the ground, or rather to still air. If we were not concerned with getting around the earth, there would be no aircrati, and no Flight, hence no letter from " Projet." As for a more comprehensive efficiency formula, thermal effi ciency would appear to depend on compression ratio and on heat losses through the walls, as in an internal combustion engine. Also, compressor and turbine efficiencies would have to be taken into account J. K. HAVILAND. Propulsion in a Vacuum IN Flight for February 17th, "AJAR" appears to have mis understood my letter stating that there is no need for pro pulsion in a vacuum once the desired velocity has been attained. This is not a theory, but a fact, and if the object is an aircraft no lift can be expected from the wings in the vacuum, so that the force of gravity would have to be opposed by the vertical jets which T have already suggested. " PROJET." THE WORLD'S REST AIRCRAFT Only Contemporaries Should be Compared IN Mr. Maseheld's article he seems to have overlooked the fact that the Germans have some very fine aircraft, two of which immediately come to mind—the Ju 88 and the Fw 190. When they came out they were the best. Also he seems to be com paring the most modern American types with British machines that have been in service for two or three years. Compare British and American machines of the same periods, please ! Another thing—what has happened to the Avro York ? To my mind it is better than any other transport in the world. To state that the Mustang is better than the Typhoon makes one think that he doesn't know what he is talking about. By what process of reasoning does he arrive at the conclusion that the " Lib." is better than the Lancaster ? Anyone who knows anything about these machines at all can see that he is hope lessly mistaken. A point to remember is that Britain was the fiist country to- produce fighter aircraft flying at more than 300 m.p.h, operationally. TATTON WINTER JOHN. Types Apparently Forgotten MR. MASEKIELD'S article on the best aircraft in the world intrigues me. I openly admit that I completely fail to see the idea of Mi Masefield's point system, so it must be borne in mind that I am not basing any of my opinions on the point system. How Mr. Maseiield, a man of undoubted authority in the aviation world, can say that the Lockheed Lightning is the best single-seat fighter-bomber in the world is, to me at any rate, astonishing. I am pretty certain that there will be a lot more air enthusiasts amazed at this statement. Has Mr. Mase field by any chance forgotten the Hurribomber, the M210 or the later marks of Ju 88? My plea is that for a high-efficiency fighter-bomber the designer does not stick to single-seaters or converted lighters, but that he develops a machine specially for the job. Now. is the Lightning specially built for this? Certainly not. The original purpose for it was escort fighter. The Typhoon, if we must be conventional and go on the "single-seater" lines, is as fast as the Lightning and pretty well equal in fire power. Also, it gets from one engine what the Lightning strives for on two. Are we therefore to swallow Mr. Masefield's almost unfounded remarks on this point? And what of his best land-based torpedo bomber? I shqi/si say that, due to its fuselage design and general features, such as crew positions, manoeuvrability and range, the Hampden is pretty high up on the list, and definitely not the Beaufighte^. The "hanging on" of the torpedo on a Beau, is most unpro fessional, and in any case the Beaufighter is primarily a ground strafer and long-range fighter, in which capacities it has per formed supremely well. The naval torpedo bomber is undoubtedly the Avenger. It is interesting to note a "bit of Hampden" about the Avenger, incidentally. We will draw a veil over naval dive bombers ! I always understood that the Commando was a long-range transport, but according to Mr. Masefield it is a medium-range job. I heartily endorse his choice of the Skymaster. That such "old faithfuls" as the Barracuda, Albacore, and Swordfish should be mentioned, even in the "some types con sidered " column, is amazing. No doubt Mr. Masefield imagines some pretty battle scene in which one or all of these primaeval manifestations competes with such machines as the Avenger. And have we enough evidence of the Mitchell's worth to quote it as the best of all twin-engined attack bombers? (and tank busters?). No doubt it would "bust" a tank if it hit it with its 75 mm. gun, or sink ships with the same weapon; but are we to forget the far more practical arrangement of four 20 mm. cannon on the Mosquito, or the experiments actually being made with 40 mm. cannon on the Hurricane? In the future we can with some margin of safety stray from the orthodox, but not in wartime, please! Exit Lightning, Barracuda, Whirlwind, etc. I make no attempt to put forward any one aircraft us ttvv best in the world. All I ask is that we indulge in a little n tr«^ spection when attempting to classify aircraft. R. FANO. Support for Masefield's Selection I RE AD the article by Peter Masefield on " The World's Best Aircraft " with much interest. I should like to take up the cudgels on the author's behalf. I suppose, in his present job he will not be able to reply himself, or we might see the sparks fly. Surely Mr. Masefield's formula does attempt to achieve an unbiased result. Some of the criticisms of the article do not seem entirely free from bias; perhaps because British aircraft do not predominate, although I see they form some of the more important categories. The comments that the comparisons are in some cases between older British aircraft and newer American types do not hold water. I have been through the list carefully, and, so far as I can see, all the aircraft compared are the latest announced in service of each individual type. Messrs. Lloyd and Lickley differ from Mr. Masefield in the fighter category. They suggest the Typhoon IB is superior to the Merlin-Mustang as a medium-altitude fighter and the Spitfire IX as a high- altitude fighter. But I understand that the Merlin-Mustang is somewhat fastei than both the Typhoon IB and Spitfire IX at medium and high altitudes; it certainly has a much longer range, as its recent escort missions prove, and I learn on good authority that in maintenance and man-hours of production the Mustang shows up at least as well as any fighter in service. So there seems to me good evidence from Messrs. Lloyd and Lickley's " only infallible yardstick," of " results, achieved in operations," for putting the Mustang at the ii'jjl in both categories. ^p Obviously the heavy bombers must be divided into day ana night categories, because the lightly armed night bomber will not do well by day and the lighter bomb load of the day bomber will be less effective at night. So I think few wiil quarrel with Mr. Masefield when he puts the Lancaster " top " at night By day, I suppose the latest Liberator might be assessed higher than the Fortress. The Americans have announced in their own reports that the Liberator B-24J has been in action for some time armed with 14 half-inch guns, ten of them in power-operated turrets, compared with 12 guns (six in power-operated turrets) of the Fortress B-17G. Besides this, the newest Liberator carries a bigger load slightly faster and farther than the Fortress. By day the Lancaster cannot •nake the grade on cruising, ceiling or armament. Mr. Bray does not seem to have read the article in detail, so he has not appreciated that the " major factors " of range and defence for day bombers (without which they surely would not reach the target) are backed up with " subsidiary factors " which include bomb load, and so on. It seems to me that Mr. Masefield's major and subsidiary factors are all intercon nected and do give the fairest comparisons yet achieve^Won all counts. And applying the yardstick, of results achieved in operation, the selections do not seem much to quarrel with. CHARLES V. WILLIAMS. •
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