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Aviation History
1950
1950 - 1408.PDF
July 7950 TEST PILOTS CONFER A Valuable Airing of Views at Boscombe Down THOUGH a number of test pilots' conventions have beenheld in the United States, none on a large scale had taken place in this country until, on July 12th, a conference of some50 pilots, representing almost all the principal aircraft and engine constructors, was held at the Aeroplane and ArmamentExperimental Establishment, Boscombe Down. In addition, the convention was attended by over 60 representatives ofA. and A.E.E., R.A.E., E.T.P.S., and other official establish- ments. The idea of holding the convention was conceived by S/L.R. A. Watts of "A" Sqn., Boscombe Down, and S/L. R. G. Woodman, D.S.O., D.F.C., Deputy Superintendent of Flying,was responsible for the organization. All the discussions were of a technical nature, and details ofthe views expressed are, understandably, not suitable for public disclosure. During the morning session, techniques for high- A. Cdre. A. W. B. McDonald, O.C. of Boscombe Down, with (left) W.C. Ruffell-Smith of the Institute of Aviation Medicine. Capt.Summers (Vickers-Armstrongs), Lt. Cdr. Richmond (A. and A.E.E.), P. G. Lawrence (Blackburn and General Aircraft) and Cdr. (E.) Wilson of the E.T.P.S., in earnest consultation. speed and high-altitude test-flying were debated, the discussion—under the chairmanship of G/C. H. P. Broad, C.B.E., D.F.C. (Superintendent of Flying, Boscombe Down)—beingbased on papers read by 5/L. Joha Derry, D.F.C. (de Havil- lands) and S/L. Watts, and upon a reply by S/L. Smythe(R.A.E.). For the afternoon session the chairman was Mr. P. G.Lucas, G.M., F.R.Ae.S., de Havilland's technical sales manager and formerly Hawker's chief test pilot. Lt. R. H. Reynolds,D.S.C. (Boscombe Down) introduced a discussion on the low- speed handling of high-performance aircraft, and there followeda paper by W/C. Ruflell-Smith, A.F.C., Institute of Aviation Medicine, on safety equipment for test pilots ; this produceda particularly illuminating discussion, nearly a score of pilots giving their views. The final subject for debate—introducedby^G/C. A. H. Wheeler of the R.A.E.—concerned the provision P»8^t pilots for the Industry and the experimental establish- At the subsequent dinner in the- officers' mess the guests wereentertained by the A. and A.E.E.; welcoming them, A. Cdre. A. W. B. McDonald, C.B., A.F.C., the O.C.D., remarked onthe great success of this first convention, and Mr. A. J. Pegg, M.B.E., Bristol's chief test pilot, expressed thanks in reply. TURBOJET LUBRICATION N.A.C.A. Tests on Supplementals and Additives SOME noteworthy research into the effectiveness of supple-mental lubricants and additives, with particular reference to the lubrication problems associated with gas turbines, isdescribed* by Mes«rs. Edmond E. Bisson and Robert L. Johnson, of the N.A.C.A. Lubrication of high-output aircraft engines is always compli-cated by three important variables, viz., high speeds, high loads and high temperatures, but the gas turbine increases this com-plication because its operating temperature range might embrace values as low as —55 deg C and as high as 205 deg C. Disparity in viscosity requirements means that, to satisfy sowide a temperature range with one lubricant, some sort of com- promise is inevitable; and such a compromise is afforded by theuse of supplemental lubricants designed to give adequate lubri- cation when the normal lubricant breaks down, and the use oladditives of the extreme pressure type. By the use of an appara- tus designed to give a pure sliding action, investigations weremade on a variety of supplemental lubricants and additives, the teat runs being made at loads from 269 to 1,017 $ (g'vmg aninitial Hertz surface stress of 126,000 to 194,000 lb/sq in and over a range of .sliding velocities of 50 to 7,000 ft/min). Of the supplemental lubricants, molybdenum disulphide(MoS.,) and graphite (C) were thought to have the most promise ; the major difference between the two is that molybdenum disul-phide has a higher chemical reactivity, which gives it a higher tenacity for steel. Whereas both materials have low friction-;oefncients at low sliding velocities, the N.A.C.A. tests showed that, as sliding velocity increased, the graphite showed an in-crease in friction, whereas the molybdenum disulphide showed * hi a paper abstracted in the March, 11)^,0. issue of the " S.A.E. Journal." a decrease. An increase in surface temperature coincident uponthe higher sliding velocity would tend to extreme the films of moisture and gases which have been considered by some in-vestigators to be the lubricating agents of graphite. Molyb- denum disulphide, however, does not depend for its lubricatingaction on absorbed films, and consequently does not show such a trend. Investigations were also made on the effects of certain oxideson the friction and wear of sliding surfaces. The tests were made with discs on which were formed solid fdms of iron oxides(Fe, O, and Pe 2 OJ 1,200 Angstrom units thick, i.e., 5 x 10—*inches. The results showed that, whereas Fe.'O, maintained a relatively high coefficient of kinetic friction throughout therange of sliding velocities, Fe., O, dropped from 0.48// at 50 ft/ min sliding velocity down to o.i/i at 5,000 ft/min, which lattervalue it maintained up to the maximum test speed of 7,000 ft/min ; the load was 269 g. Surface analysis by electron defrac-tion has shown that Fe, O A is the predominant film material onlubricated engine parts that have been effectively run-in, and that Fe2 O3 is predominant on failed surfaces. It is suggested,therefore, that Fe 3 O, could serve as a supplemental lubricant. The additives tested were confined to varying percentages ofsulphur in purecetane. Friction was reduced virtually progres- sively with increase of additive proportion up to the maximumtested value of 1.5 per cent, sulphur content. However, all proportions had in common an increase of friction as slidingvelocity was increased above 1,000 ft/min. These results were interpreted as possible evidence of a critical sliding velocityabove which the additive did not adequately perform its func- tion as an anti-weld agent because there was insufficient timefor the additive to react chemically with the surface to farm an effective low-shear-strength film.
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