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Aviation History
1944
1944 - 1037.PDF
MAY I8TH, 1944 FLIGHT 539 1 CORRESPONDENCE The Editor does not hold himself responsible for the views expressed by correspondents. The names and addresses of the writers, not necessarily for publication, must in all cases accompany letters. M A.T.C. OFFICERS' DRESS Dissention Deprecated AY I be permitted to reply to your correspondent, Leonard Taylor (Editor of the A.T.C. Gazette), vide issue of Flight dated May 4th under the heading "A.T.C. Officers' Dress." One is getting somewhat tired of the childish reference of some people to this matter. Surely it is time the whole ques tion was dropped once and for all. The Air Ministry has already bowed to the pleadings of the aggrieved and permitted the use of the G.S. cap "off duty," which should meet the case. Anyhow, how about the Home Guard: is he any different ? I have been an officer in the R.A.F.V.R. (T.R. branch) since the commencement and before that in the A.D.C.C. I am very proud of the Corps, and its achievements. Let us not permit therefore attempts at dissention within our ranks. "CANDIT." THE DUCTED RADIATOR Phenomenon with Ovoid Body REFERRING to Mr. Shoham's reply Flight,'April 20th) to . Squadron Leader Brotherton's letter concerning the forces on a Townend ring, it is interesting to observe the action of an ovoid body with a gaseous jet issuing from the blunter end. According to the laws of jet reaction, the body should move in the opposite direction to the jet. Actually it tends to move in the same direction. INDUCED AIR FLOW NEGATIVE DRAG COMPONENT RESULTANT AERODYNAMIC FORCE (ON ONE SIDE) THEORETICAL DIRECTION OF MOTION ACTUAL DIRECTION OF MOTION This phenomenon is explained by the fact that the jet in duces a flow of air over the surface of the body, and this in turn produces aerodynamic forces similar to those on the Town- end ring (though in this case the air flow is in the reverse direction). H. HONE, B.Sc. GUNPOWDER AS A FUEL Not a Question of Calorific Value I KNEW it would happen! The moment I saw that you had published my letter advocating the use of gunpowder to drive motors under the section of Correspondence on jet pro pulsion of aircraft (Flight, March 16th) I knew I should be called upon to deal with hot air. But it is not a question of calorific value, and Mr. Ogston (Flight, April 13th) is thrusting up the wrong duct. I suggested the use of gunpowder specifically for " fan- driven" aircraft, as I fondly believe anyone who bothered to read beyond the title could see. Indeed, I am grateful to Mr. Gould (Flight, March 30th), who both read and understood my suggestion, for getting straight to the point and talking of "producing pressure in, say, a locomotive boiler." Inci dentally, I am also grateful for his confirmation that "gun powder should give better expansive economy than spirit." Mr. Ogston, on the other hand, is thrusting his B.T.U. in a vacuum;' and strangely (as one would expect) helping us forward at a mighty rate—for he has confirmed my previous opinion that overheating could certainly not be held up as an objection to the use of gunpowder as a pressure medium; in fact, his figures quite simply show that a pound of gun powder will, on burning, produce only one-fifteenth of the heat produced by a pound of petrol—this after Mr. Gould had confirmed that the same pound of gunpowder has decidedly more "piston-pushing value" than a pound of potrol. By the way, it is the very fact that gunpowder does not rely on the atmosphere, which lends the argument its strength. And so the only objection is Mr. Gould's; to wit, that it is the cost of gunpowder which is the ruling factor. So could somebody who knows please tell me: (1) The actual difference in cost of gunpowder and petrol, weight for weight, as mass-produced to-day; and (2) the actual difference in expansion upon combustion— which seems to be the only criterion involved in this parti cular case. And,.for t3iose who missed what went before, may I again briefly state the case; A machine-gun-cum-boiler providing the pressure to drive the engine, at a great saving in fuel-weight; independence of atmosphere; with a pressure-medium as non- inflammable as steam; and (so long as the "boiler" has not leaked overnight) instantaneous starting up even at the North Pole. "DRIVER." INFORMATION LEAKAGE " Gen " from Unofficial Sources COME of your correspondents have lately accused the A.T.C. »J of giving away information on secret aircraft types and of receiving more "gen" than the R.O.C. The first charge may be true, as the average age of the Corps is fairly low, and not every cadet is security-minded. I do deny, however, that they obtain this information through A T.C. official channels. R.A.F. personnel and sometimes members of Spotters' Clubs are very ready to give information to anybody interested, as we are. In my three years as an A.T.C. cadet I have never seen an Air Ministry recognition handbook, though G. A. B. Short states that these are "often" left at the disposal of cadets, and the small amount of secret information I have received has been harmless stuff (e.g., Warwick) which was published within a few weeks. Incidentally, cadets are not allowed to enter operational types except in the case of machines under repair and stripped of operational equipment. It is probable that any "gen" given away by the A T.C. has already been distributed through the medium of careless R.A.F. and N.A.S.C. members, from whom I, for one, have learned much about the latest aircraft types. E. G. FARMAN (Cadet). SORTING OUT THE SNAGS Retests Not So Numerous JUDGING by "Test Pilot's" remarks (Flight, April 20th) on my reply to "Indicator's" article lelating to "Sorting Out the Snags," I should imagine that either he is the type who is fond "of a second flight, or that he has been extra ordinarily unlucky. If on the other hand the percentage of required retests are as high as he quotes I would say that it is high time that something was done about it. With regard to the undercarriage failing, this would be an extremely serious matter, as I refuse to believe that it could be caused by the airflow pressure under normal conditions. The pressure available at the hydtaulic ram far exceeds the air pressure exerted on the unit due to airflow. I can under stand the tell-tales sticking after inspection if they are of the bead type, but the electrical contact type have eliminated this snag. Perhaps "Test Pilot" refers to the occasion when the unit has been subjected to excessive taxymg tests, due to a hare getting up, resulting in excessive strain and malalignment prior to take-off! The snag with the directional gyro is that in the case of military aircraft, with which I presume "Test Pilot" is also concerned to-day, this unit is invariably received^in situ on the blind flying panel on embodiment loan and as such is fitted en bloc, no test being carried out other than to see that the vacuum pump causes the turn and bank gyro to right itself on engine run. From the time this sub-assembly is tested to the time of flight test, considerable transportation has taken place and frequently the balance of this unit has
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