FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1951
1951 - 1634.PDF
FLIGHT, 24 August 1951 CORRESPONDENCE . . . The prime fallacy in the whole argument is that the air over the sea is different from, and separated from, that over the land; and, therefore, by implication, that Coastal Command exercises sea power and not air power. Nothing could be farther from the fact. "Icarus" admits that air power played a dominant role in the last war, and, therefore, demolishes his own later doubts as to whether in fact air power exists as a third force. In modern global warfare, sea, land and air forces are all necessary to the successful conclusion of hostilities. Overall strategic direction is, however, a sine qua non, and to break up the offensive power of one of the three partners by parcelling out for purely tactical considerations just does not make sense. Even allowing that at times the strength of Coastal Command has been unsatisfactory, that is due entirely to the political con- siderations which dictate the funds allocated to Air Ministry. The first duty of the Air Staff is to ensure air superiority. This must rest first on bomber strength and secondly on fighter strength for the defence of the base. If this superiority cannot be achieved, the allocation of Coastal Command forces is sheer waste. The Navy and its carriers themselves cannot operate without air superiority and CANNOT PROVIDE IT. Coastal Command is by no means regarded as "of secondary 231 concern" by the Air Ministry any more than it is by the Admiralty'In the former case, air superiority mu»t come first. In the latter, it is an adjunct to the operation of ships and as such relies for itsstrength on an Admiralty allocation of available funds as between ships and air. If the Admiralty operated shore-based aircraft forthe attack of purely naval targets, the force so allocated would reduce by that amount the strength available for the overall airstrategy. From the point of view of the Admiralty, however, a more seriousdefect is that in time of need they would be unable to call upon a supreme effort by, if necessary, the entire resources of the RoyalAir Force. A situation is easily conceived in which the whole air strength available may be required to deal with a naval threat.During the last war Bomber Command was called upon more than once to supplement Coastal Command and Naval Air forces. It is only by the integration and unification of all air forces thatmaximum air power can be obtained and can be directed according to the needs of the supreme strategy. That is the over-riding con-sideration and such purely administrative problems as training cannot be permitted to obscure it. But even as a debating point thetraining aspect offers "Icarus" an unsteady platform, certainly not a weapon. All Naval officers must serve, and rightly, as ship'sofficers to qualify for promotion. Naval strategy and not air strategy is and must be their background. Epsom, Surrey. W. N. COMMING. GAS TURBINE MATERIALS A Note on Some Steels Developed for use Under Exacting Conditions THAT the steel manufacturer "must always be one step ahead"is the burden of these notes on the use of special steels in gas turbine development and production. Prepared by a memberof the technical staff of Firth-Vickers Stainless Steels, Ltd., they review the materials used in the early Whittle units, and someobservations on steels used in gas turbines today are included. IN the ten years that have passed since the first flight of theGloster E.28/39, the revolution that has taken place inmethods of aircraft propulsion is truly remarkable, especially when one bears in mind that the aircraft industry itself is littleover 40 years old. It is interesting to reflect, therefore, on the complex problemswhich have faced the designers, engineers and, in their turn, the steel and alloy makers, in whose hands rests much of the respon-sibility for the success or failure of so many enterprises. When work started in earnest on the Whittle unit in 1936, the bestmaterials available had reliable physical properties, without excessive creep, only up to about 500 deg C. The steel used forthe initial experimental work was Firth-Vickers "Stayblade," and this material itself represented a considerable advance on thosepreviously available; it was a development of "Staybrite" corro- sion-resisting steel, and was used for the discs in the W.i enginewhich powered the E.28/39 on its first flight. In fact, because of its higher creep strength, "Stayblade" continued in use for discsfor practically all the development work until the end of 1943. From 1937 to 1939 there was a steady improvement in theengine's performance, and the conditions imposed on the turbine blades became increasingly severe, largely owing to the higheroperating temperatures . employed. With the introduction of "Rex 78" steel by Firth-Vickers research laboratories in I939»further increases became possible. "Rex 78" was used for the blades in the W.i and W.i.X engines as it possessed considerablyimproved properties at elevated temperatures, being capable of working at a temperature 100 deg C higher than other materialsunder trial at that time. This was a very remarkable achievement, and when the E.28/39 first flew, powered by the W.i.X engine,both the turbine blades and the nozzle blades were made in "Rex 78." It may, incidentally, be placed on record that W/C.Whittle (now A. Cdre. Sir Frank Whittle) wrote to the late Dr. Hatfield on November 10th, 1941, "Indeed, without the specialsteels which you have developed, it would not have been a practicable proposition. You have therefore provided an essentiallink." Another technique which progressed at the same time as the"lain development of gas turbines was the process of producing stator-rings and similar structural components by the centrifugalcasting process. This method, pioneered by the Firth-Vickers foundry and continuously developed by them, has made theProduction of these components a sound economic proposition. In the early days rings were made by forming Stavbrite F.D.P.and H.R. Crown Max steel bars to ring shape, welding the joint, neat-treating to remove welding and bending stresses, and finallymachining the ring to the desired section. This method was used »>r producing the Staybrite F.D.P. steel rings for the W.i and proved a lengthy and costly business. Today numerous gas turbinecomponents are made by the centri-spinning process, and, with modified techniques, complicated sections in the improved heat-resisting steels are in regular production. Many other components for jet units are made from heat-resisting steels in sheet form and operate under conditions of high temperature and stress. Staybrite F.D.P., as used in the originalengine, is still employed extensively. Although this steel is a standard corrosion-resisting material stabilized with titanium, itpossesses useful strength and resistance to oxidation at temperatures up to 800 deg C. As the designer's demands have increased, so the materialsoffered to him have improved; but the steel manufacturer must always be one step ahead. Many different alloys have beendevised, with varying success, and amongst these Firth-Vickers have comparatively recently developed a series of new creep-resisting steels for turbine discs, rotors and blades—components which have to withstand high stresses at temperatures up to800 deg C or even higher. Firth-Vickers 326 and 337 steels have been used in various forms, from blade stampings to large rotorforgings. "Rex 448" is a new ferritic steel for gas turbine com- ponents where service temperatures are not so high as to warrantthe use of an austenitic steel. "Rex 467," another recent develop- ment, is an austenitic steel which has creep-resisting propertiesof a very high order, but which does not contain in its composition the more scarce and expensive alloying elements upon whichgood creep resistance usually depends. Research continues on both sides, the metallurgical and thefabrication aspects. The problems of today are attacked on the basis of experience gained with the problems of yesterday, butthey are no less acute than those which were overcome and culminated in that historic flight of the E.28/39 ten years ago. FORTHCOMING EVENTS Aug. 25. Exeter Aero Club: Display. Aug. 25-26. S kef ness Airport: Aerial Week-end. Aug. 25-26. International Air Circuit of the Dolomites, Italy. Aug. 31. Helicopter Association: "Operational Employment of the Piasecki Helicopter," by F. N. Piasecki. Lecture followed by Fifth Annual Dinner. Sept. 1. R.N. Air Stations Gosport and Lee-on-Solent: Air Display. Sept. 2. A.B.A.C. Summer Convention. Sept. 3-7. R.Ae.S. and I.Ae.S.: Third Anglo-American Aeronautical Conference, Brighton. Sept. 3-8. British Interplanetary Society: International Congress on Astronautics. Sept. 9. Society of Model Aeronautical Engineers (Northern Area): Model Flying Festival. Sept. 10. R.Ae.S.: 39th Wilbur Wright Memorial Lecture—"The Well- tempered Aircraft," by A. E. Raymond. Sept. 10-16. Battle of Britain Week. Sept. 11-16. S.B.A.C.: Flying Display and Exhibition, Farnborough. Sept. 15-16. International Rally, Parme, Biarritz, France. Sept. 22. Daily Express South Coast Air Race, Shoreham. Sept. 25. Milan international Grand Prix. Oct. 4. R.Ae.S.: Seventh British Commonwealth and Empire Lecture, "Air Transport in New Zealand and the South Pacific," by A. V-M. Sir L. M. Isitt, K.B.E., R.N.Z.A.F. Oct. 31. R.Ae.C: Jubilee Ball.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
