FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1947
1947 - 1595.PDF
SEPTEMBER ISTH, 1947 F LIGHT 315 The Anglo • American Conference ward flight it this can be done at anefficiency equal to. or better than, that of a cooling fan. However, there isanother consideration to the use of a cooling fan in helicopter power plants,this being what can be termed the fly- wheel function The inertia of the fanmu5t be adequate to provide satisfac- tory idling characteristics of the enginesince the rotor is not engaged during the starting and idling phases of engine run-ning. Of course, the fan must also be light. This controversy must be settledby the designer, but it has been estab- lished that a well-designed helicoptercooling fan will weigh from 0.05 to 0.08 Jb/b.b.p,. Realization of the power cost of cool-ing with a fan leads to a search for substitute methods and one thus comesto the exhaust ejector. Satisfactory ejectors can be built at a weight of from0.075 to 0.09 lfo/b.h.p., falling roughly in the same weight category as a coolingfan. After touching briefly on suspensionmethods, Mr. Stanley went on to consider the vertically mounted engine, comment-ing that although this is not a "must" it has the advantage of very direct driveto the rotor with inherent simplicity and low weight. Most single-rotor and somemultiple-rotor craft have the power plant located within the body, thus beingclassed as "submerged installations and, since the rotor loads are appliednear the top of the body and the landing- gear loads near the bottom, there mustbe continuity of structure between these points; unfortunately, the structure hasa wonderful affinity for blocking accessi- bility to the power plant. Of all majorcomponents of the helicopter, the power plant zone is probably the most criticalfrom the access viewpoint. Turning to the subject of a betterhelicopter engine, Mr. Stanley pointed out some desired trends in piston-enginedevelopment to make this type of unit more suitable to the specific needs of the helicopter. He stated that considerabl*improvement in power/weight ratio if needed and, particularly considerableresearch should be devoted to cooling requirements since reduction of poweirequired for cooling pays big dividends in any helicopter. There is also adefinite case for supercharging in the small engine class, especially it theengines are designed to make boost-powei available at sea level for take-off andhovering. Methods of maintaining approximately constant engine speed atpowers varying from 50 to 100 per cent h.p are required to suit both the cruis-ing and hovering conditions of flight, since the helicopter rotor operates .atapproximately constant speed. Much research, too, is needed in the matterof determining minimum flywheel re- quirements from the standpoint oistarting, idling and accessory drive inertias and, as a last but particularlyimportant point, it is essential that it can be mounted either vertically, hori-zontally or in an inclined position with- out redesign of lubrication or accessorysystems. Standardized Cockpit Design Risk of Too Many Standards : The Need for International Agreement: A Case for Functional Arrangement THERE are definite indicationsthat both here and in Americagreat efforts are being made tosimplify and improve the layout of cock- pits, and the problems are being tackled *in several ways. In addition some degree of standardization both of con-trols and instruments is being sought for all aircraft. There is, however, a realrisk that the principal purpose of these praiseworthy individual endeavours maybe defeated because too many groups tackle the subject without knowledge ofeach other's work. For example, the Air Ministry in this country may appoint acommittee to study and recommend, some of the major aircraft companieshere and in America may also be tackling the subject, and the U.S. Navy also hasa study group. If and when these groups eventually get together each may .haveproceeded so far that it would be too late to consider the pooling of ideas. Theneed for international planning is, how- ever, most'obvious. Some views' on the subject of layoutwere expressed in a paper read before |^ S.A.E earlier this year, and sum-marized recently in the Society's journal. The author was Commander N. R.Richardson, cockpit development co- ordinator of the U.S. Navy Bureau ofAeronautics. He dealt with his subject under a series of headings—the basicprinciples of cockpit design—and the main points were as follows: — (1) Transfer of control: The pilotshould not be required to transfer control of the aircraft from one hand to theother during take-off and landing. Commander Richardson remarked thatthe principle had been violated for years. For example, landing gear, flapsand canopy control were located on the right-hand side of the cockpit, whichmeant that immediately after take-off the pilot was required to remove his left hand from the throttle, transfer it tothe stick and fly left-handed while he operated these controls. (2)transfer of vision: On many air-craft it was necessary for the pilot to look inside the cockpit at a critical period tofind contiols. (3) Controls forward for take-off:For years there was no rhyme or reason for the way in which many importantcontrol; operated. For example, air- screw controls were mounted on the aftend of the power control quadrant and moved up and down rather than foreand aft as was the throttle. Some instal- lations actually had the idle cut-off posi-tion at the forward end of the quadrant, just beyond the full rich or take-offposition. The author concluded that certain controls should operate fore andaft and that they should be forward for take-off, making it simple for the pilot.and almost foolproof. (4) Motion of controls to correspondwith motion of equipment operated: Although the principle would on occa-sion seem to conflict with the " forward for take-off'' rule it was logical then toapply the one that made the most sense. For example, trie landing gear was oper-ated in a vertical plane—up for wheels up and down for wheels down. Flapswere in a similar category. (5) Separation of controls: In manyaircraft f%e flap and landing gear con- trols were in the same area and often sideby side. Just how many crashes this had caused would never be known. Theywere now located in different areas of the cockpit where they would be oper-ated in a logical sequence. (6) Combination of controls: In manyaircraft emergency or auxiliary controls were located in remote recesses. The aimwas now to combine the normal and emergency controls in one, or at leasthave them adjacent where the pilot could find them and operate them with a mini-mum of time and effort. (7) Economy of motwn: in manycockpits there was no thought given to the location of controls that must beoperated in sequence. (8) Economy of time: Controls mustrequire a minimum of time and effort to operate on the part of the pilot. Itwas required that the pilot only take the time necessary to flick a control orswitch rather than hold it during the cycle of operation(9) Functional arrangement of con- trols : By making controls remote operat-tiiig it was possible to make them small and locate each one where it should befrom the functional viewpoint. (10) Streamlining: The first step infairing-in equipment was the develop- ment of radio and electrical consols.Shortly afterwards the same consol treat- JJ. ment was applied to all power plaftt and"~: trkn tab controls on the left-hand side of the cockpit. The result was surpris-ing. Despite the addition of many con- trols the cleaned-up versions looked- simpler and were easier to operate. (n) Crash and injury hazards: Effortswere still being made to get all equip- ment cleaned up and recessed and allsharp objects 'lad been removed or faired in More attention was being given tobody clearances, head, knees and elbows. Commander Richardson then com-mented on seating, pilot escape (with special reference to ejector seats). Ofthe prone position he said "We must know much more about human limita-tions under high negative and positive accelerations before we know whetherprone cockpits are desirable." He added also " We know that pilots must be com-fortable if they are to be effective and safe." We were now faced with high-speed aircraft and still did not know if noise or vibration would be problems.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
