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A. Introduction

i The terms, /et and turbine, aiLhou;dh usecl: i syuonomourly to describe flighl engirres, some-..1.-'_ Limes represent quite dilfereuL clesigns. ,l,here-{, fore, bhese lerms need to be defirLerl carej\rllJ' iu a:)i-t-- book such as this.

TheTet engine farnily includes t hr: r'ockel, jel:, ranr--

jet, pulse-jet, and gas turbine Dower.erl jeL. 'flregas burbine powered jeb is fu.r-tirer brokeu dow,nirco the turbojei, turbopropeller:, Lurbosir_af t, andturbofan bypes. 'I"nese four t;ypets ctf engines arebhe ones more commonly fould in aircraft; toclay.

Ali of Lhese eng_ines have evolved t,h,r:ough history.

in their oftil way and for their o.,vl purposes, lVe' n'ill explore this historiurl sig.nificance arrd Lhen

concetrtraLe on the gas turbine powerplants ubiliz.ed for aircrafL propulsion.

1. f{erp's aeolipiteTod.ay's moclern t,rrbine eng-irre is based on thereacLion pri:rcipie fornulaLed cen{.uries ago.

One of the earliest accounls is of an ligl'pLianmalhemabician arrd philoscpher named lleron,sometimes referred to as Hero, li'ho ilvenled adevice which conve::leC sLea-in pressure to m"-chanica-l power. Current hisloria.ns set ihe datesomewhere becween one fo bno hundred yearsB.C. The desigaer of the skeich of llero'.s inven-tion. ihe Aeolipile, is not known ald t,lre acbualdevice might have looked quite differentl.y.

\ltrat is known is that by heating water in aclosed vessel of sorne kind ald try supplyingsiea;r co opposi:rg nozzies ruounceri un o ior,aringsphere, Hero was able to sr:ccessfully tlemotslrace Lhe reaction principle, \\;'helher he was ableto put hts Aealipile to pracLical use ; is noL

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Llistory of TurbineIIn.gine Developrnent

Fig. I I{ero's aeoliPile.2. Chinese rochetAnother early application of the'reaciion princi'ple can be seen in rocket develoornent as early as1100 A.D. By utilizilg black powder, the Chinesewere able Lo perfect a solici-ruel rockei.

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Fig. 2 Chinese rochet-historicalir clear.

In records available todal-. one can see referenceto a battle about 1230 A.D. in which the Chinesechronicled rhe use of the rocke! as a militaryweapon.

3. Newton's ftorseless carriogeIn 1680, Sir Issac Newion, a British astronomerand physicist, designed and produced a model ofa steam powered vehicle. His invention embodiedthe jet propulsion principle which is known to ustoday as Neqton's Third Law of Motion _ forevery action there is an equal and opposite reac-tion.

By mounting a water-tight sphere on a four_wheeled carriage and then heaiing the water tosteam, Newton proposed io eject the steam back_ward propeiling the vehicle forward. Although itis apparent that thrust would be created in thismarlner there is no record of the vehicle's suc-cessful operation.

Fig. 3 Newton's horseless carri.age.

steam created was directed onto the impulsewheel. The wheel was thus rotated. and used todrive a crude cogwheel reductlo"-g"u, system.This mechanism, now on display ii tfre BritishMuseurn, is said to be the fore.unner of themodern turbosupercharger.

5. Moss turbosuperchargerIn 1900, Dr. Stanford A. Moss, while studl,ing foran advanced engineeing degree, publishdh athesis.on the gas turbine engine. He used thisearly work in his future development of the firstgas turbine device for an atcraft apolication. Asa General Electric Company engine; in 191g, hes.upervised the production of the gas turbine-driven llbosupercharger for rJciprocaringengines. This development brought about manynew low weight, high temperature strengti: ma-terials needed for industrial gas turbLe ex_perimentation which was going on concurrentlyin Europe and the United Smt.r.6. Sir Frank WhittteFrank Whittle, while a cadet in the British RoyalAir Force College, wrote a thesis advocating ihegas turbine engine for aircraft propuision. In1930, he patented the first turbojei, pure reactionengine.

His engine was to use a compressor impellersimilar to }doss's; driven by

^ tuibin" wheel.

During the earllr.thirbies, Wtrirtle served as aregular officer in the Air Force where his dutieswere as an engineer and test pilot of reciprocatingengine powered aircraft. The reciprocating en-gines was in an accelerating dwelofmental stageat this time and Whittle was disiarisfied wiihwhat he referred to as ,.their obvious limitationsof altitude and top speed".

Between 1g30 and 1g3b \4rhittle exhaustedevery avenue for help, but he was unsuccessful inobtaining government or privai,e support for con-structing his turbojet engine. The idea prevaiiedthat as a business proposition his engine was asimpractical for business as it was for flight. Hefailed to renew his patent during this time and indiscouragement put his idea aside. However:, mil-itary build-up and political unrest in Europe in1936 prompted some of Whittle's friends to ap-proach him about forming a private company to

4- Branca's turbine deuiceThe frst turbine device came into use in 1629,when-the Italian engineer Giovanni Branca pro-duced the firsl steam-driven impulse turbine.Branca's desiga was 'of a ciosed water-filledvessel with one nozzleopening aimed at a turbinewheel" The vessel was hJated by solid fuel and the

Fig. 4 Branca's turbine-

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slart rievelopment of a proLolype cn13ine. 1.lrer pro-posal led bo the forrnation of l,tou,er Jr:l:;, LLcl.,financed enlirely by privaLe [ur-rcl:;.

'I'lre engine developed was a cetttrifu,gJal fToLu Lvr-bojet of Lhe pure reaction bype. ,l'hat is, it.s l.olalfli-ns0 ca.me from reacbion to Lhe hot ga_r sLrearrremitfed from a propelling notr.k:. 'L'he engirrr:feaiured an impeller t1'pe complessor, a one.Jrir:cecombustion chamber, and a single st.age [rii-binewheel. The gos turbine engine rer:eives ils name irrthis desigrr. Fio'wing gas di-ive.s l.he {.url:irre n'treelq,hich is abtached to, and ui,ilizerl l,o rjrive, l,ireco;:rrresscr inp:! I e5.

This engine evenlual.ly creaLeci abouI l],Oflil shafLhorseporver on lhe tesb sta.nd. At Lhis poirrL lr1939, Porver Jets Lid., was gir.en an Air N{inis[ryconiracL lo produce a iiighL engine.

\\hittle relates ia hx book, Jet --

'l-he ,St.ory of aPioneer, bha[ one of the biggest obsiacles he h:dto overcome was oilr?in;ng Lhe,necessary highferrp"*ralu:e saer.5ir rneial for [he comirusLiorrand turbine sections. The firsL cornbuslr:r rvit,hflJght iL:tegrity tock \l,'hittle t.luee l.ears ofrepeated iesii:rg ."o produce, and h;rrj. Len separai.ecombustion chanbers.

In N{ay of i941, the Wirittle \4r-l v;as inslal.lecl inbhe Glosber Aircrafb Ccmpany's nervly prepared

Fig. 5 A -

Dtagmm of lVhit.tle's reiterse-flowcombustion chamber, B

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F-useloge arrange-ment of the E28.'39 espeimental oirplane.,

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rnociei E28139 aircrait. The aircraft made its in-itial test flying ab its design speed of 40O mphwiLhouL complicabion. Ifs gas turbine porverplantis said to have produced approximately 1,000lrounds of thrust..

Developmenl *-as iranediabely sbarted on the\\t-2, a mui',ipie combustor, more powerfully de-signed engine which wouid, in Ig43, power at,ivin engine aircraft, the Ir{cteor.

_The NIeLecreventrrally would successfuiiy engage Lhe Ger-lnan Vl, a pu-lsejet powered buzz bomb, in theonly 7ef-uersusTet confrontation of WWiI.

Widttie did not enjoy lhe same success as ciid irisilvenbion. During the.war years Lhe governmentabsorbed more and more control over his inven-Lion, d,imir:ishing iris role bo the poinl thab in 1948he ret.ired iroin bhe Royal Air Force.

7. Genncn s.nd ltaltan DeuelopmentsAl accuraLe accou-lt of Germa:: deveioprcenL isobscured by circumstances of the time prior to\\'nVlI. The lleinkel Airerafb Company did de-velop the Heinkel-Hirih turbojeb po*'ered a;r-craft, the Heinkel 178, flowrr in August i939.Whether conceived by independent developmentor by using \Yhit,tle's ea;iy work is a matter ofconjecture. Neveri,heless, the Heinkel L?B isgiven the credit as being ihe first purely jet pio-pelled aircrafb flighb in history. Ibs gas turbinepowerplani p:'oduced approximabely 1,100pounds of birusl.

[;ig. 6 The German l{einhel HE-178, flown onAugust 27, 1939, was the firsi jet aircraft fllght.

'fhere has been much written aboub the jet pro-pulsion devices of this era and of the first jeb pro-pelled flight. Some historians give crediL to theItalians. who flew a Caproni-Campini aircraf[ atabout Lhe u.me as the iirst fiighi oi iae Heiiiiei178. This a.ircrafb was designed by Secundo Cam-pini of the Caproni Aircraft Company. But, if oneis referring to a pure jet propelled flight, u'ervould have to agree that the Italian aicraft did

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frg:! A*ericats first jet ptanq the geTkp-SLe'Aifttome\ was-flown on bctober l, jg42.

not meet this qualification. The compressor ofthis aircraft's powerplant was driven by a liquidcooled reciprocating engine rather than by a iur_bine wheel in the gas path. The Caproni aircraftwas also limited to a maximu*

"p""h of 205 mph.

The speed of the Heinkel 1?B is not known, butwhat can be seen is that the Germans did not'pur-sue the centrifugal impeller type of compressor asdid the Italians or British in their later develop-' ment.

In 1941, the Germans flew the ME-262. The air_craft was equipped with two B.M.W., more ad-va:rced tTpe axiat flow gas turbine engines. Theengines were rated at approximatily 1,g00pounds ofthrust each and.thearrcraft's top speedwas slated to be in the 500 mph range.

8. Early ameican gas turbine deuelopment

!^eneral H.H. "Hap" Arnold, while in England in1941, was impressed with the p.ogrur! buirrgmade srith the gas turbine po*"r"d Jircraft as atacticai weapon. He procured a \4rhittie engine,and was instrumental in securing an Air Forcecontract for the General Electric Company inSchenectady, New york, for research and de-veloprnent of this new concept iriaviation.

This company was chosen because it had themost current technology of the day in turbosuper_charger production; also some of iis affiliate com_panies had been supporting Whittle's work in Bri_tain.

The Beli Aircraft Company of Buffalo, New york,was chosen to construct the first jet airplane. Theurgency to support the nation's war effortp,recipitated very rapid progress in redesigning:le_ ^Whittle engine for added power ouiput. in7942, at Muroc Field, California, the geti Xp_Sgwas Lest flown, powered by two General ElectricGE-IA engines producing i.,6b0 pounds of thrusteach.

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The,era of t-he gas turbine engine, fueled by a lowgrade petroleum product simi"lar io lr"r*".ru, *u,raunched-

America did not use the jet airplane in WWII,but did_go on to use the basic *o* oiWt ittle andGeneral Electric for future *ifia.r;, "om1lr".i"ut,and industrial development.

9- Commercialaircraft deuelopmentThe British tested the tirst turboprop poweredpassenger liner in 1948, the Vickers Viscount.This aircraft is still seen irr sei:vice today. TheBritish also tested the first turbojet poweredairliner, the DeHavilland Comet in- 1949. Thisfour engine airliner, placed in seryice in 1gS2, ex_perienced structural fatigue cracking, resuiting inhigh altitude decompression. -atastrophiccrashes occured from this mysterious phenome-non of the time, and in 1g54 the Comet wasgrounded for extensive testing.

?"ri1r_q this period the Boeing Company of Seat_tle, Wash-ington, made u piorr".ri.rg'move tobring America into the comirercial aiic.att iieid.Utilizing Pratt & Whitney engines a"rr"top.Jlo,themilitary, Boeing invested ieavily in what wassaid to be a notable 16 million aoUar businessgamble. The result was the world renowned Boe-ing ?07, which after years cf testing went iatoservice in 1988. This company today producesmany models of narrow-bodied airliners as well asthe.largest passenger liner flying tod.ay, the wide_bodied Boeing ?4?.

FiS. 8 A -

Boeing Z4Z B -

BAc/AerospatialeConcorde.

The Boeing Company tribd to launch the UnitedStates into supersonic airline service with theirBoeing 2707,boL Congress, und.er pressure from

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the environurenlalisLs, voted dowtt {.ltt: [r-rrrr.lirrl; inLhe [ate sixLies. Ai bhaL [inre il; v;irs felL t.lraL lrililr{light, in Lhe 60,000 feeL alLitr.rtle ratrlre, rvor.tltlseriously affecb Llte ozone layer'

Ilditor's Note: Ozone provides tr sr:rer:tritr11 1lro-lection frorn t,he harmful ulfraviolct; ra1's l;r1111[1'11'rJ-ng the eart-h.

I'lorvever, t.he British in ptrrLirershil: v, it lr {-hel-rench, builL and placed in{.o selvice ;r -*liglrl-l)'srnaller supersonic jetliner narrrecl Lhe (iorl