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[SOME ASPECTS OF THEDESIGN OFSEA-GOINGAIRCRAFTB y A. G O U G E , B.Sc,A.F .R.Ae .S . , Genera l M a na g er of Short Brothers

Being a lecture delivered before theRoyal Aerona utical Society onJanuary 8, 1931[Concluded from page 64.)

! The Range of a Large Flying-BoatSO much has been written of late regarding long-rangeflying-boats, that ismaynot be out ofplace here if Igiveyou theactual figures that have been obtained on a large;flvin" boat recently completed by the firm with which 1 am, connected. This flying-boat, which wasnotbuilt entirely forrange purposes, hasnormal civil safety factors at theweightunder consideration. In other words I consider it useless totalk of range obtained by reducing the safety factors below; those required for a normal certificate of airworthiness.On Fig. 16will be found the range of this boat plottedj against useful load exclusive of fuel.' From thecurve it will benoted that theabsolute maximum1 range is approximately 2,400 miles, the whole of the usefulload being fuel. At a range of 2,000 miles the useful load| apart from fuel is 4,000 1b. and finally the total useful load'is lfi.fiOO lb., which represents 44-5per cent, of the total1 weight of the flying-boat. From theabove it appears that itis possible to flyfrom 1,500 to 2,000 miles in still air in onehop, carrying a fair amount of paying load, but I am afraidthe charge per lb. would have to be high to make such aflight a paying proposition.Single-Strut Engine Mounting and Absence of ChineStruts

A glance at the front view of the flying-boat in the photo-graph will, at once, suggest two further points in design,which, having received dueattention and consideration, haveresulted in a considerable cleaning up of the air frame andconsequent increased overall efficiency of the machine in theair. I refer to :

(1) The nstallation of the power unit.(2) The absence of struts from under the engine strut toth e chine of the hull.

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Dealing with (1), it has for long been recognised that theusual methods of strutting engines between the wings, withtheir attendant vibratory struts, etc.,results in considerableinterference with airflow around theadjacent wing structure,entailing excessive airdrag.A satisfactory attempt has nowbeen made to overcomethis difficulty by installing the power unit in a monocoquenacelle into which isbuilt, either integral with it or separate,one very robust vertical member between the wings in theP-ane of each front and rear spar. As an additional refine-ment this member may be tapered, being widest at thejunction with thenacelle. Suitable fairings areincorporated0 nuse all necessary pipings, wires, etc. In the tandemarrangement shown these members are stayed horizontallyray another much smaller member carried" to the caban'eracl- T n e stress assumptions imposed upon the verticalmembers were : four times engine weight horizontally plustorque and thrust reactions, and flying loads from various

cases. In addition, periods of vibration of both verticalandhorizontal members were investigated for comparison withengine periods.The monocoque nacelle itself is cut down to its minimumfrontal area consistent with efficient cowling of theengineandgeneral accessibility to parts requiring frequent attention,such asengine pumps, magnetos, plugs,etc.TANK TESTS ON '/a" SCALE MQDE.I OF SINGLE IL0A1fcTECT Of NOSE-DIVING M0ME.NT5 ON RUNNINO ANGLL

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The resulting structure is satisfactorily rigid under allrunning conditions of the engines, entailing very little addi-tional weight andmaking forincreased simplicity, eliminatingthe attendant trouble of vibration on a large number of pinsand bolts to such an extent that maintenance required onthe structure itself is nil.On later installations this vertical member has been usedfor supporting the radiator above the nacelle, and has thusreduced another source of interference with thewing.Dealing with (2), chine struts have always been trouble-some by reason of liability to damage by attendant boatsand resistance andinterference with theneighbouring wing.Hence, an endeavour has been made on the aircraft, asshown on the photograph, to substitute a structure in lieuof these external members. This has been done, and thestructure faired over by gradually " blowing up " the wingsection from its junction with the main plane to its pointof contact with the hull framing. This " blow-up " iscarried out on chord as well as depth, and at the hull thesection is approximately twice the normal depth of wing.The resulting shape between the two spars is ideal for fueltanks, inasmuch as it ispossible toextract every gallon of fuelfrom thetank in anynormal attitude of themachine withoutthe necessity ofemploying anyelaborate sump arrangements.This scheme of bracing is, however, slightly heavier thanthe normal type of chine strut, but the increased weight ismore than compensated for by theoverall gain in efficiencyto themachine. Undoubtedly, these twopoints alone havehad a marked influence towards improving the I-/D of thecomplete structure.T H E D I S C U S S I O N

In opening the discussion, WING. COMM. CAVE-BP.OWNE-CAVE said that hewould feel very glad if Mr.Gouge couldcom-pare the efficiency of the single float seaplane or the singlehull flying-boat with that of the twin float seaplane or twinhull flying-boat. He questioned whether this was entirelya matter of float interference. He then queried whetherMr.Gouge's suggested remedy ofmoderately supercharged enginesfor assisting thetake-off in tropical climates under conditionsof varying atmosphere anddensity wasentirely sound. Hefelt that in many cases a fall in density was due to a rise intemperature and in such conditions he doubted whether asupercharged engine would be a sound remedy. Commentingupon thetests in the tank carried out by Mr.Gouge, he said83

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that these appeared to have been done in calm water andhe would like to know whether anything had been done inproducing a standard wave for such tests, since the powera pilot had to hold a machine down on the water and preventpremature take-off due to waves was very important . Amatter also affected by waves was the test which Mr. Gougehad mentioned as carried out to determine the proximity ofth e bow wave to the propeller disc and Wing Comm. Cave-Browne-Cave felt that this would be much more valuable ifit were done in rough water conditions. In conclusion hesaid, he would like to congratulate Mr. Gouge for his daringbut entirely successful production of a single strut enginemounting.Mr. H. E. W I M P E R I S (Director of Scientific Research)said he would very much like to congratulate Mr. Gouge on hiswork at Short's, since from the beginning he had alwaysviewed Mr. Gouge's work with admiration. Mr. Gouge wason e of the first to start work on a tank solely for aircraftpurposes and this tank differed very largely from that whichhad hitherto been in use for ships. The range of speeds to bedealt with was very much greater and the work was thereforevery much larger. Mr. Gouge's tank though small had provedto be very accurate, and the tank which the Government wereconstructing at Farnborough was based very much on theresults of hiswork. In fact he said they were greatly indeb tedto Mr. Gouge for his pioneer work and were profiting thereb y.I t wasinteresting, he said, to note that the t ank at Rochesterwas not nearly so large as those used either in France or theU.S.A. and he would be glad, he said, to have Mr. Gouge'sviews on thefuture of t anks in general. Mr.Wimperis said hewas interested to hear that Mr. Gouge considered that wingtip floats would always be necessary even for boats very muchlarger than the Do.X. He himself, however, considered thatwhen we came to boats of 100 tons or more displacement themetacentric height would be found to be such as to make theboat stable in itself and the use of wing tip floats thereforeunnecessary. He would like to ask Mr. Gouge, he said,whether he considered experiments on the lines which hadbeen suggested by the Principal Scientific Officer at Felix-stowe as likely to produce good results . These consistedessentially of building a, say, half-scale model of the hull ofa flying boat and then taxying it on the water by means ofthe upper half of a Moth attached to it and between the Mothan d the hull they proposed to insert a steelyard arrangementfor measuring the drag directly, much in the same way ashad already been done on certain Parasol monoplanes.

M R . H A N D L E Y P A G E said he was particularly interested inthe single strut type of engine mounting and would like toknow how the torque reaction was taken. A nother pointwhich interested him was the wake effect that the four-enginetype of installation seemed to have. He quoted instancesduring the end of the war in his own large bombing machineswhich, incidentally, Col. Sempill had carried out tests on,

where there was a very appreciable difference in the effective-ness of the controls when the front or rear engines on eitherside were stopped. He said he would like to know whetherMr. Gouge had any knowledge or data on similar effect; inamachine such as the " Singapore II."SIR A L A N C O B H A M said he felt that Mr. Gouge alread*-hadsufficient questions to answer and there were only one or tworemarks he would like to make. He said that he had hadconsiderable personal experience of Mr. Gouge's methodsand had always had the greatest confidence in him. Withregard to the difficulties of take-off in the tropics in conditionsof varying density, he said that his personal experience wasthat these were entirely inconsistent, and t h a t he did notthink either heat or alt i tude was the controlling factor butt h a t it wassomething obscure to do with the place in question.He quoted instances, when, in the Sudan with a temperatureof 1203 F. in the shade, he had experienced no difficulty intake-off whatever, yet sometimes in other places at very muchlower temperatures he had had the greatest difficulty.M R . O. E. SIMMONDS (Designer of Sp ar tan A ircraft, Ltd.),said he would like to offer his thanks to Mr. Gouge for soopenly publishing the mass of information which designershad always known must exist at Short 's . He felt, he said,

t h a t it was a greaty pi ty that Mr. Gouge had found itimpossible to include a similar curve to No. 15 for theweightof hulls, and he hoped tha t it would be found possible to includethis when the lecture was issued in the Society's Journal.There was another curve which he suggested might bevaluable and t h a t was a range curve plotted against airmiles per gallon for increasing weights of hull. He thenreferred to the remarks made by Mr. Gouge on the subjectof single float seaplanes, and he pointed out t h a t we in thiscountry have confined ourselves to flying boats with singlehulls or seaplanes with twin floats and he felt that wewereprobably too conservative in this m att er . Bo th Germanyand Italy, he said, had shown their enterprise in developingother types and he made a plea for us here to investigateboth the twin hull flying boat and the single float seaplaneMR . F. TYMMS (Chief Technical Assistant, Directorate ofCivil Aviation) said that he was particularly interested in thequestion raised by Mr. Gouge as to the distance and diffi-culties of take-off in the tropics. He pointed out that theatmospheric densities to be found on the Cape-Cairo route,which is shortly to be opened, were very much lower, andin some cases might be only 0-78. This ma tter was thereforea vital one for civil aviation, and one which must be investi-gated very fully. A nother question was t h a t of makinglandings and taking off not only in small spaces and confinedchannels, but also across wind, and he would like to knowwhether Mr. Gouge had any data on the relative merits of

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FLIGHT, J A N U A R Y 23, 1931

, . Single-hull flying boat and the twin-floatemplane inthese'conditions. There wasonec-int hesaid, which struck him asrelevant,an'l that was that it would appear that withiiich-wing monoplane-seaplane, such astheValetta, there would be less chance ofdamage to the wing when operating innar-r>w rivers such as to be found on theNile for there the banks are almost in-variably low and thewing would ride clearover any small obstructions, whereas withthe biplane flying-boat type both the wingand its tip floats was a source of constantdanger.M R . LANKESTER PAR KER (test pilot forShort Bros.), when called upo n, said th er ewas little he could add to Mr. Gouge'sinformative paper, but he would like, ifhe might, to answer Mr. Handley Page'squestion concerning effect on the controlson the tandem arrang eme nts. Hesaid thathe had tried every conceivable arrange-ment of engines both on and off, on theSingapore II, and had not been able todistinguish any difference in the effect ofthe controls.MR. R. C. K E M P (Director of Air Survey Co., Ltd.)saidhe heartily a greed wi th Sir A. Cobham's views concerningthe inconsistency of a take-off in tropical conditions. Hehimself had found that in many cases, in spite of havingfloats which Mr. Gouge had told him were e xtre me ly efficient,he had been ab le to take off an overloaded D.H. 9a, whileunder other conditions he hadfound it impossible to get off.It was generally found, he said (jokingly), that some sillytrouble such as water in the floats was the reason. Forinstance, inRangoon under outwardly exactly similar condi-tions to those in Calcutta he had found it quite possible toget off, whereas in thelatter place he hadsometimes found itwell-nigh impossible.

MAJOR GREEN (Armstrong Siddeley Motors Limited) said,when asked, that hethought that a moderate degree of super-charging might be permissible in tropical conditions withmodern engines, but t h a t heconsidered other steps should alsobe taken forimproving thetake-off.DR. LACHMANN said that in Germany they haddiscovereda law of similarity between the floats andhulls, and a paperhad recently been read in that country which was very usefulfor comparing theperformance of thetwo. One firm hesaidhad found thetake-off was increasingly better accordingly asthe size of thehull increased, and hewondered whether per-haps the resistance of a hull increased less in regard to itssize than didt h a t of thetwin floats of a seaplane.WING-CO MM. T. E. H O W E said that he agreed with Sir A.Cobham's view s. Th ey had found that very often in thePersian Gulf it was easy to take-off at anyt ime of day andunder any conditions of temperature or density, but t h a tsometimes in other places great difficulty wasexperienced.He then put forward a plea forgreater attention tothe crews'living qu arte rs in large flying boats. These, hesaid, were toocramped. O ne could no t stan d up ; inth e nose ther e was insuffi-cient room for comfortable working when mooring theboat,and although they w ere bett er t ha n t he y used to be he feltthat they could beimproved greatly. The tailplane, he said,was often too low and was apt to suffer damage from itsProximity to thewater in rough seas. Healso asked that the

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lower centre section might, inthe case ofmulti engine mach ines,be kept clear for use as additional deck space in tropicalclimates.M A J O R K E N N E D Y put forward the suggestion that thenomenclature of flying boats and seaplanes was at presentleading them into difficulties since for instance, you alreadyha d theSingapore / / andwhen discussing this machine onewould be apt to getmuddled if one would have to announcethe fact that it was flying to Singapore. This would alsoapply tosuch boats asthe Calcutta and the Southam pton, andhe suggested that thevise of numbers would beeasier.M R . L. L O W E R in referring toFig. 5said that it was shownt h a t thehull efficiency was much greater when thehull was

slightly trimmed down forward. In this case hewould like topoint outt h a t the tail loads involved in holding thehull inthis trimmed forward position greatly detracted from thecurve values as shown, and thecurves were therefore onlyrelative andcould not be taken as an actual measure of theloads involved.M R . G A R N E R said that he felt that Mr.Gouge wassome-what pessimistic about wing tip floats, because the size of thefloat would surely bedetermined very largely by its position,and since thelarger thehull became the lower theC.G. went,and therefore a still smaller float was require d. W ith regardto thetake-off in thetropics hesaid that hethought it mightbe a m atter of engine power, since engine power wasverylargely inproportion to thedensity.M R . O.S H O R T (Short Bros., Rochester) referred to the factt h a t he had thepleasure of meeting Mr. Gouge every day ofhis life, and said that hewould like to congratulate him onsuch anably delivered paper. Hefelt sorry forhim, however,in that he had so many questions to answer and suggestedt h a t themajority of theanswers should be in writing in theJournal of theSociety.CO L. SEM PILL in concluding thediscussion said there wereon e ortwo points hewould like to raise. The first one was inregard to the use of stainless steel and particularly withregard tostainless steel sheet. He said that reference had beenmade to aCalcu tta which had been inuse inthe M editerranean

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0 nouldhave som ething between 10 and 12 ft. wide. On the questionof late ral sta bility , he said, the C.G. does no t alway g0down in very large boats , since the C.G. of the superstructureis always higher, and as this, of course, increases with tin-size of the boa t, the C.G. of the whole is also kept u p. Hesaid he was very interested in the proposed full-scale result*,at Felixstowe, and would like to know more about themIn answer to Mr. Handley Page, he said " yes," the reactionis take n in bending in the struts . W ith regard to Sir AlanCob ham 's take-offs IH th e tropics , he said no dou bt he hadgot off, bu t since he had seen the record he knew that insome cases it had tak en over 90 sec. In an swer to M r. O. F..Simm onds, he regretted th at he had not sufficient d ata toconstruct the hull curve asked for, since they had not confinedthemselves at Rochester to either military or civil machines,and were unable to compare the two types for this purpose.In answer to Mr. Tymms, lie said that matters were conflicting,since the Vee-bottom hull and float which was essential forefficient operation in rough water was not so efficient incalm, and was certainly very bad for cross wind landings.As matters were, floats were probably about equal to boatsfor this . In answ er to Mr. Ke mp , he said he would like toknow how long it took him to g et off som etimes . Finally, inanswer to Col. Sempill, he said he felt quite sure that stainlesssteel would eve ntu ally become unive rsally used. Concerningcorrosion on the machines in the Mediterranean, he saidthey had the second Calcutta back to the works after it hadrun ashore, and there had been absolutely no evidence ofcorrosion at all, and the refit had necessitated no replace-ments, all parts being replaced as they were.

KING'S CUP AIR RACE, 1931THE Royal Aero Club has received the approval of HisMajesty the King to the following regulations togovern this year's Air Race for the King's Cup :Competitors .The entrant and pilot or pilots andpassengers must be British subjects.The R ace shall be confined to " A ma teurs."N either the e ntran t, the pilot, nor passengers (if any)shall be engaged as proprietor, partner, director, official oremployee of any firm of manufacturers, dealers or operatorsin aircraft or aircraft engines, or employed as a professionalpilot. R .A .F. pilots of amateu r sta tus, as defined above,are eligible.In order to confine the Race to those of amateur status,the Royal Aero Club reserves the right to refuse to acceptany person as entrant, pilot, or passenger without assigningany reason.Aircraft.The Race is open to any type of bona-fidecivil aircraft. The aircraft, including the engine or engines,

must have been entirely constructed in the British Empire.For the purposes of the R ace, a bona-fide civil aircraft isan aircraft which was originally designed, and subsequentlyconstructed for use in civil aviation activities.In any question regarding the eligibility of any aircraft,the decision of the Royal Aero Club shall be final.The aircraft entered shall have been registered in thename of the entrant and Certificate of Airworthiness issuednot later than May 30, 1931.Handicap.The aircraft will be handicapped for thecom plete circuit, according to estim ated performances. Theminimum speed at which aircraft will be handicapped willbe 80 m.p.h.Course. It shall be a on e-day race, over a course ofapproximately 1,000 miles, the longest leg not to exceed200 miles.The Royal Aero Club reserves the right to hold an eliminat-ing contest if necessary.< s > < > < $ > < $ >THE SCHNEIDER TROPHY

O|N T hursday , Janu ary 15, the A ir Ministry issued thefollowing communique :" In September, 1929, a few weeks after the British victory in the Solent,the Air Ministry announced that the Government had had under review thefuture policy in regard to the Schneider Trophy contest in 1931 and sub-seque nt years ; an d tha t, after careful consideration, it had been decidedthat a Royal Air Force team would not again be entered, thus leaving Britishparticipation to private enterprise under the auspices of the Royal Aero Club.The main considerations influencing this decision were that, owing to Govern-ment participation in recent years., the contest had assumed a character notin accordance with the intentions of M. Jacques Schneider, its originator andthe donor of the trophy, and that, although the entry of a Royal Air Forceteam had given a much-needed impetus to the development of high-speedaircraft, sufficient data had now been collected for practical development inthis direction, and that the large expenditure of public money involved wastherefore no longer justifiable." Since December last, however (when the question of the validity of theItalian and French entries was settled by the Federation Aeronautique Inter-nationale), strong representations have been made to the Air Ministry for areversal of this decision, either in whole or part, that is, either that a RoyalAir Force team should be organised by the Air Ministry, or that Royal AirForce pilots should be loaned to the Royal Aero Club or some other privateorganisation. The matter has accordingly been again considered." The Government has decided that in the present financial situation theexpenditure of public money involved (not less than 80,000 if a Royal AirForce team were organised) is not justified, and that their previous decisionmust be strictly adhered to ; the defence of the trophy and all^nc iden talexpenditure must be left to the R oyal Aero Club or private enterprise, and theGovernment should not give any assistance either direct or indirect, whetherby the loan of pilots, aircraft, or other material, by the organisation of therace, by the policing of the course, or in any other way."On Monday, Janu ary 19, the com mittee of the R oyal

Aero Club, with Sir Philip Sassoon in the chair, met to

consider the new position. The meeting lasted a little overan hour. On its conclusion the following sta tem en t wasissued :" At a fully attended meeting held this evening the committee of the RoyalAero Club considered the question of the Schneider Trophy contest, and it wasdecided to adjourn the meeting in order to explore every avenue whereby th"trophy m ay be defended. The club will leave no stone unturned to achievethis object, and feels sure th at this is in general ha rmo ny w ith th e wishes ofthe British public."The trophy itself is now on its way to Buenos Aires fordisplay a t the British Ex hibition , which will shortly beopened there by A ir Marshal H.R .H. T he Prince of Wales.A suggestion that Gen. Balbo should be asked to fly thetrophy back to Italy in his seaplane still needs confirmation.On the mo rning of Tuesday, 20th inst., th e Com mittee ofthe Club again approached the Air Minister, and askedwhether, if 80,000 (which had been estimated as the costto the Government of organising the race and defending thetrophy) were raised privately by the Royal Aero Club, theGovernment would then undertake to defend the trophy.The Air Minister referred the question to the Cabinet thesame evening, and the reply made was that even in that can"the Governmen t would do nothing. N ext day Sir Phili;'Sassoon raised the matter again in the House of Commons,and m et with a further refusal on some vague excuse cf" policy and principle."

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