-=NAC& ,- LOW-TEMPERATURE IGNITION-DELAY CHARACTERISTICS OF SEVERAL ROCKET FUELS WITH MIXED ACID IN MODIFIED. By Riley~O.

Save this PDF as:
 WORD  PNG  TXT  JPG

Size: px
Start display at page:

Download "-=NAC& ,- LOW-TEMPERATURE IGNITION-DELAY CHARACTERISTICS OF SEVERAL ROCKET FUELS WITH MIXED ACID IN MODIFIED. By Riley~O."

Transcription

1 n bupy RM,, ~ E50H16 -) -=NAC& ~ - & -T -+,- RESEARCH MEMORANDU~ LOW-TEMPERATURE IGNITION-DELAY CHARACTERISTICS OF SEVERAL ROCKET FUELS WITH MIXED ACID IN MODIFIED OPEN-CUP-TYPE APPARATUS By Riley~OMiller Lewis FlightPropulsionLaboratory Cleveland,Ohio - Tl!10~nt -M!= CIUd!idlllS3rmU10n dk =ti4lb FWUOti~ ottb Udki SW Mthluh nmdnx ofb abrmsa Act,U9C!0tX31- SS lb trmusmladcn or Um -r mm urautbrhedprxn Ispmhtdmdt-3lm InfOrnat!a m clm3fe9d ~-~ti- ~ ~J-~-d- Oftbhued 3 mvanmmt WbIuvaa inferem t4umtmd smm5cltiaw 0fkmu nloymy UxldbcrOHOaWb of Mcamilymud bnimfornatbmeaf NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS WASHINGTON ~)cto~r 17, Hfi9HW4AL

2 _ _ - --,! 6YS-*-,, -&r+ 5 k,, i!:, 5 bvbbb, b QI?ADEOF OfflCERMAKM CHAtiii aooq+_md_m

3 NACA RM E50H16 TECH LIBRARY KAFB, NM -_ Iillllllillllllllllllllllllllllllllll: 0143 LOg g CJl LOW ~ NM?IONALJUWZS41RYCOl~T!D1Z FOR AERONAUTICS RESXARCHMEMORANDUM IGNITION-DELAYCHARACTERISTICSOF SEVERALROCIJ1T FUEISWITH MIXEDACID IN MODIFIED 0E3?!J-CUT-T3!E APMRNIUS By Riley O Miller SUMMARY An tivesti~tionwas conductedto determinepossiblerocketfuels that ignitespontaneouslyat low temperatureswith mixed acid (nitric lus sulfuric)in a more reliablemanner than cruden-ethylaniltie fmonoethylaniline ), a rocketfue1 in currentuse By meansof a benchscaletechniquea numberof fuelswere determinedto ignitewith mixed acid at subzerotemperatures;severalof thesefuels were investigated over a more extendedtemperaturerange With mixed acm, the followingfuels showedgenerallyshorterand less variableigcition-delayintervalsthan cruden-ethylaniline(over the temperaturerange of approximately80 to -40 1?): mixedbutyl mercaptms, 70-percent(by volume)furfurylalcoholplus 30-percent cruden-ethylaniline,63-percentfurfurylalcoholplus 7-percentcrude N-ethylaniline ad 10-peroentmethanol,70-wrcent furfuryl alcohol plus 30-percentqlene, 35-peroentfurfurylalcoholplus 65-percent cruden-ethylamiline,90-percentcommercialgm turpentineplus 10-percentpropyleneoxide,pure N-ethyl-aniline, and commercialgum turpentine Sumaries of self-ignitiondata for theseand other fuels are presented INTRODUCTION Recentexperimentsin which the rocketpropellant,cruden-ethylaniline(monoethylaniline) and mixed acid (nitricplus sulfuric), failedto ignitesatisfactorilyat low tem~rature (reference1) indioate the necessityof a knowledgeof the self-igmitionpropertiesof certainrocketpropellantsat low tempemtures,as well as at modemte temperatures,inamnuchas rocketsmaybe requi~d to startat high altitudesor underarcticconditions

4 Q-+ NACA RM E50H16 f In the evaluationof rocketpropellantsto determineself- Ignitability,optimumeconwy of materialsand safetyto personnel make small-scal experimentalesttites of ignitioncharacteristics 8,desimble beforefull-soalee~riments are undertakencare,huw- 3 ever,must be exercisedin makingesttites of propellantignitability from data obtainedwith small-soaleignition-delayapparatusbecause suchfactorsas mixingand geometrytend to restrictnumerioalresults to the apparatusused The ignition-delayintervalis, in general,an arbitmry quantitydefinedfor a specificapparatusas the time interval betweendefinitestartingand endingconditions In spiteof the gecmetryand mixingrestrictions,previous investigations(reference) indicatethat not only lengthsbut also degreescd variationof ignition-delayintervalsobtainedwith emazlscaleapparatusare sigm?ftoantlycharacteristicof propellantcabinations Moreover,combtitionsof Propellazrbs that give com~ratlvely shortdelaytitervalsand smallvariationsin delay intervalsin smallsoaleignition-delayexpertientsalso show desirableignitim dmracteristics in rocketengines,, Variousinvestigationshave been conductedin Gezmany,England, and the UnitedStatesin which small-scaleappamtus was usedfor the of propellantself-ignitioncharacteristics Ṫhe methods employedmay be dividedinto threegeneralclasses: (1) open-cup methodsin which one propellantis made to fall into or is injected into the otherpropellant;the ignition-delayintervalis determined eitherby high-speedphotogmphy or by electronicequipment(references to 6); ()a methodused in Englandh which the pro~llants are impingedas low-velocityjets in a horizontalplane in open air; the ignition-delayintervalis calculatedfrom the distance thepropellantsfall from the point of to the point of igniticm;and (3)methodsIn which the propellantsare injectedat high velocities intoa chamber;the i~ition delay is measumd by high-speedphotography or electronicequipment(references7 to 9} The open-oupmethodsare prefemble to the tipinging-jetmethods for investigationsof the comparativeself-ignitionpropertiesof a numberaf propellantcombinationsaccordingto referenoe Although the open-cupmethodstend to give considerablevariationin ignitiondelay intervals,the data ap~ar to be more independen than data obtainedby othermethodsof arbit?w?ily selected fuel-oxidantratios$ whichmay or may not have been optimumfor any particularpropellant combination(reference) Furthermore,the open-cupmethodsare more convenien to set up and less time-consumingin obtainingexperimental results Althoughsome ignition-delaydata from open-cup-t~eexpri- ments are availablefor propellantsat low temperatuzws(refereon~4), most of the experimentsin which thesemethodswere used have been conductedat room temperature ~ - - t

5 s NACA RM I150H16 3 An tivestigationof the self-ignitionchaz%ctertsticsat moderate and low temperaturesof posstblerocket-propellantcomb-tions was conductedatthe NACA Lewis laboratoryto suggest,for use in rocket w engines(reference1), sevwal availablefuels that remainfluid and 8 ignitespontaneouslywith tixed acidsat low tempemiiures in a more reliablemanuerthan cruden-ethylanimne AmcUfied open-cupmethodwas used to obtatiignition-delaydata for a~ro-tely 60 propellantcombinationsinnovationsb cooling the propeltits andbr~~ them into contactand in timingthe ignition delayprovidedan amtus with which the data couldbe convenientlyobtained * SummaMes of the igrctticn-delay data obtainedare presenteahereti Both lengthsand variationsh the of time that elapsesbetweenthe first contactof fuel ad oxidantana the first detectableappearanceof flsne)have been consideredh making est-tes of the of the fuelswlthmixedacias AJ?mRAm The functionof the appamtus was (1) to bring the fuel and the oxidantto a selectedtemperature(80 to -50 F), () to bring the fuel and the oxidanttitomutualcontactat this temperate, and (3) to measurethe time intervalbetweenthe startof this contactand the firstappearanceof detectableflame The appamtus (fig1) consistedof a tempwature controlsystem,a firingmechanism,ma a means for Temperature-control system- The temperature-control systm (fig1) consistedof a clearglassdewar cylinder(~ in I D), a coolantprep,a dry-icebskh and heat exchanger,and the requires pipingand valves At the beginningm the experiments,the temperature hside the lhwar cylinderwas controlledby two manually operated needlevalvesbut laterthe temperaturewas automaticallycontrolled by an electricsolenoidvalveand an adjustabletemperature-actuated switch The Dewar cylindercontaineaa thermometerfor indicating coolanttemperature Firing mechanism- The firing mechanism used is shownin figure1 A 1- by 8-inchpyrex ignition-typtest tube conta~ a glassampule about 9/16 inch h diameterwas held partlysubmergedin the coolantin the Dewar cylinder A stainless-steelrod when hit by a weight-that fell 6 inchescrushedthe ampule,releashg the fuel under the surface

6 4 ~-- NACA R14E50H16 i of the acid oxidant A simpletriggerpin was used to supportthe droppableweight (approximately04 lb) b tube beforef~= The microswitch,whichwas mountedon the firingmechanism,actuated the timingapparatuswhen the weighthit the rod Ignitian-delay measurement- The instrumentationby which the ignition-delaydata were obtainedincludeda photoelectricpiokupunit, an electronic-mhy-mpltiierunit,em oscilfitor,and an e-bctronic - counter The circuit was so designedthat the counterwould register the totalnumberof cyclesfrom the osolllator (1000 or 10,000cps) betweenthe instantthe weighthit the rod amimicroswitchand the instanta flash of light,sufficientlybrightto affectthe photoelectricpickup,appearedh the test tube A high-speedmotion-picturecameracapable of speedsup to 3000 framesper secwndwas used to photographand time the aotionof severalfir-s The camerawas modifiedto permitthe recordingof timingmrks on the edge of the film as it was e~sed Thismodificationconsistedof a smallargonbulb Insidethe camera,connectedto the outputof a calibratedoscillatoranotherargonbulb connectedto a batteryin serieswith the microstitchon the firing mechanismwas photographedto iudicatethe instantthe mioroswitch was tripped FUELS Some M the fuels investigatedwere usedas supplied,otherswere blendsor mixtures CrudeN-ethylaniline- CrudeN-ethylaniline(monoethylaniline) admixtures of cruden-ethylanilinewith furfurylalcoh?l,,5-&lmethylfuz%m,hydroxybenzenes,aminss,or variousotheradditiveswere investigated The cruden-ethylanilinewas a commercialproductobtained frm the Bureauof Aeronautics,Departmentof the Nav The following analysisis the averageof severalsamplesof cruden-ethylaniline: Ignitioncharacteristicsaf pure N-ethylaniline, pure N,N-diethylaniline (constituentsof cruden-ethylaniline),and sevemalpure N-ethyWiline - - additivemixtureswere also invesqgated, ~

7 a u NACA RM E50HI6 5 Fuzfurylalcohol- xyleneblends- Beoauseof the low viscosity and the availabilityof xylene,blendsof xyleneand furfurylalcohol were investigated Comercial w turpentine - Ignitionpropertiesof commercialgum tmpntine and mifiuresof turpentine,respectively,with propylene oxideand otheradditiveswere investigated A constituentof turpentine, a-~inene,was also in~stigated- Mixed butylmeroaptans- Beoausethey are readilyavailablefrom petroleum,mixed butylmermptans were investigatedthe ccmpositton (referenoe6) was approximately: Meroaptan I?ercent by volwne Isopropyl( )CH%H 1 ~-l?ropylch3 % HsCHd3H(andtert-butyl (CH3)3C*SH) ~ 3 sec-butylch3(ch5)ch-si 37 =butyl(ch3)chdx* SI 7 ~-~tyl CH3*CH-CH*H*SH # s 11 Amyl C5HllSH 1 O=TS For most of this investigation,a mixes acid, whichwas used as an oxidant,was _prepare&from reagent-gzade95-percentwhite fumingnitric aoid and chemicallypure oleum (70-peroentHS04 plus 30-peroentS03) The compositionof the acid approachedthe specificationsof the cmmercialmixed acid uses in rocketengiaes This laboratory-prepared acid was used beoauseit apparentlywas more desirableas a reference oxidantthan comercial acid, inasmuchas ccmmeroialacids may more likelycontainvariableamountsof trace impuritiesthat might act as catalystsor inhibitorsfor more accuratecomparisonwith rocket experiments(referenoe1), ccmercial mixed acid was tiedfor some of the firingswith oruden-ethylanilineand with 70-percentfurfuryl alcoholplus 30-percentcrudeN-ethylanilineana for all the firings with mixed butyl meroaptaas

8 ~* NACA RM E50HI6 Q The followingare the avez=geanalysesof the mixed actds: Mixedaoid Percentby weight Laboratoryprepared Commercial Nitricacid HN03 and nitrousacid EN0 (ashn03) Sulfmic acid,hs04 Nonacidiccomponent- (by difference) I 39 athe nonacidicccnnponents were,preswnedto be mostlywater PROOEDORE The tip of an ampule,in which 1 milliliterof the desiredfuel had been sealed,was insertedinto the drilledend of the smashingrod; and a test tubewas slippedover the ampuleand clam~edh the firing v mechanism The test tube was partlysubmergedin the coolantin the Dewar cylinder ati the tri~er pti and the weightwere set in place, as shownby figurs1 The acid (3ml) was then transfer~d to the test tube by means of a remotelyoperatedsyringe The acid and fuel were allowedto coolfor about 15 minutes (A mock-upof ttieapparatuswith a thermocouplein an ampuleof crudei?-ethylaniline submergedin m-d acid in a test tube showedthat the fuel reachedequilibriumtemperatureat -40 F from room temperaturewithin10 min) After the cooling period,the triggerpin was pulled out of the guidetube by means of a str~, lettingthe weightfall on the rod and the microswitchactuator, breakingthe ampule,and startbg the tiudngsequence The temperature of the coolantb the Dewar cylinderprior to the firingand the ignition-delayintervalafter the firingwere recorded After each firing,the appamtus was washedwith water and with acetone EVALUATION0? METHOD Lag in aypa mtus - The methodused was checkedby high-speed motionpictures Severalfilms were takenof the test tube with aa illuminatedbackgroundto show the actionof the propellantsin the apparatusduringthe firingsequence Otherfilmswere takenwith no etiernalilluminationand with the instrumentsin operationin orderto checkthe rate of responseof the timingcircuit Most of the films were takenat appro=tely 1000or000framesper second,in order to obtainthe best possibledefinition,thesepicturesof the apparatus were takenwithoutthe coolantbath; therefore,the propellantswere at room temperature --* ~, -

9 w NACA W lz50h16 7 The shorttitervalduringwhich the appaz=tuslxroughthe propel- lantsinto contactis shownby the positiveenlargementsfrom high-speed motion-picturefilms (fig), which are silhouettephotographsof the ~ appamtus takenduringthe first 0003secondof the ttied sequence % Two inertimiscible liquidstakenat approximatelyopoo1-secondintervals are photogmphed in figure(a) The viscositiesof the liquids in the ampulead in the test tube were 80 and 6 centistokes,respecti~~, thus the viscosities& crude N-etWl=~~e and mi=d acidat low temperatureswere approximatelysimulated The action of 70-wKent furfurylalcoholplus 30-percentcrudeN-ethylanil~ and ccmercial mixed acid,a combinationthat producedshortignitia-delayintervals, is presentedin figure(b) Figure(c) showscruden-ethylaniline and commercialmixed acid,a combinationthat gave longerignitiondelay intervals The first verticalcolum of photographsshowsthe beforethe micro-tch had been trippedby the weight The secondcolmn showsthe apparatusapproxhnately0001 secondlater; the microswitchwas trippedh each case The neti two col~ sh~ the apparatus000and 0003 second,respectively,after the first photographswere taken As shownby thesephotdgmphs, the liquids w were in contactwith each otherwithin000 secondafter the microswitchwas tripped;in the case of 70-percentfurfurylalcoholplus 30-percentI?-ethylaniline, a preliminarynonburningreactionwas alreadyunderway Otherhigh-speedmoticmyioturestakenwith no externalillumination showedthat ignitionoften startedwith a seriesof intermittent flashes,which evidentlycausedscatterin the data obtained The iatensitysad the lengthof flashesa~parentlyincreaseddurhg the earlypart of the ignitim ~ocess and the measuredignition-delay intervalwas the titervalbetweenthe trippingof the microswitchand a fhsh of sufficienttitensityto affectthe photocelland stop the thing circuit A well-definedcorrection of the instrumentresponse with high-speed motionpictureswas complicatedby the frequent startdmgof ignitionwith this seriesof flashes on four records, however,a flash on the film precededthe timesrecordedby the electronicttierby not more than 0003 second ~ each case the photocellapparentlyrespondedto eitherthe first or secondflashregisteredon the film Photographicevidencethus =Cates that the combinedlag h the ampulebreaking,the contactingeach other,and the instrumentsresponmng to a flashmay be 000to 0005 second The imticn-de~y intervals re~rted heretiare the uncorrectedvaluesread from the electroniccounter Variationsk Qni tion-delaydata - The data obtaim+dfram these experiment substantiatethe hypothesis(reference) that degreesof variationas well as lengthsof the lag in ignition-delaydata may be functionsof propellantccmb=tions E=mples of these tendenciesare

10 8 NACA RME5C)H16 a illustmtedby figure3, where iguition-delay intervalsaf crude N-ethylamil~ ~ a fresh solutionof 70-pe&ent furfurylalcohol plus 30-percentcrudeN-ethylanilinewith laboratory-~eparedmixed add are shownplottedas functionsof temperaturethe sporadicand variablenatureof cruden-ethylanilineis illustratedby frequenijinstancesof no ignitionat subzerotempera- E turesand bya maximumdeviationfrom the fairedourveof about F 04 second,which occurredin the low teqerature region The ignition-delaydata of the furfurylalcoholplus cruden-ethylaniline blendwere much less scatteredwith a maxinnmdeviationof about 003 secondfrom the fairedcurve Comparisonsof theseand other pro~llant combinationsindicatethat the scatterof resultswas more a functionof the propellantcombinationthan of the ignition-delay timinginstrumentation As a mnsequence of the tendencyfor ignitim of certainpropellant combinationsto occurdver a range of time,a largenmber of firingsd each propellantccznbination at varioustemperatureswould be requiredto eliminateall elementsaf uncertaintyin compring one w combinationwith another Becausee~ediency requiredthat a nwnber of possiblepropeluuxtsbe consideredin a shorttime,a high degree of certatitywas sacrificedh obtainingsome of the Uta The results,nevertheless,providea choicefrom which propellantcombi- nationsmay be selected for furtherresearch RESULTSAND DISCUSSION Summariesof the ignition-delaydata are so presentedin tablesi and II that estimatesof the ignitabilityof the various propellantcomb-tions may be made For each propellantcombinaticm the maximumand minimumignition-delayintervalsat one or more temperaturesare presentedin orderto indicateapproximately mnge in time overwhich ignitionmay be e~cted As a furtheraid to such estimates,the gecunetricavemge of the ignition-delayintervals at each of thesetemperaturesis presentedand the numberof firings is indicatedgeometricaverageswere used inasmuchas in some cases the ignition-delayintervalsvariedwith temperaturein an approximatelye~onentialmanner The spreadsin temperatureoverwhich the groupsof data am averagedare small (lessthan 10 F total spread for 90 percentof the data) Approximatekinematicviscositiesat and specific gravitiesaf some of the fwls are given in tableiii

11 6 NACA RM E50H16 9 Compa risen of propellants- Severalfiringswere made with crude N-ethylanilineand the laboratory-prepared acid at subzeroandmoderate temperaturesin orderto establishthe behaviorof a fuel knuwn to have G poor ignitioncharacteristicsat low temperaturesin a rocketengine 8 (reference1) Ignitioncharacteristicsof a numberof otherfuelsmd ~~~ fixtureswere investigatedby two or more fti~s at approximately Scme d? thesefuelswere selectedbecauseof (1) apparent ignita~ilityat subzerotemperatures,() probableccamercialavailability,and (3) fluidity(lowviscosity)at subzerotemperature;the selectedfuelswere then tivestigatedmore extensivelyover a temperature range of approximately80 to -40 F With the laboratory-~e~redmixed acid the followingfuels (in estimatedorderof decreasingignitabilitywvestigated over the temperaturezamge of appro~tely 80 to -40i 1?tetiedto more readilythan cruden-ethy~lti (compositionis given in percentby volume): 70-peroentfurfurylalcoholplus 30-percentcrudeN=ethylaniline 63-percentfurfurylalcoholplus 7-percentcrudeN-ethylaniline and 10-percentmethanol 70-percentfurfurylalcoholplus 30-percentxylene 35-percentfurfurylalcoholplus 65-percentcrudeN-ethylamiline 90-percentcommercialgum turpentineplus 10-~ercentpropylene oxide Pure N-ethyleniline Commercialgum turpentine ~ a limitednumberof experimentsat low tempemture (approximately -40 F) the followingfuels also intervalsthan cruden-ethylaniline(compositionis given in percentby volumeunlessotherwisenoted): FurfurYlalcohol 95-per~entcommercialgum turpentineplus 5-percentpropylene oxide 50-~rcent cruden-ethylanilineplus 50-gercent,5-dimethylfuran 70-percentcrudeN-ethylanilineplus 30-percent,5-dlmethylfuran 70-percentturpentineplus 30-percentpropyleneoxide 95-percentcrudeN-ethylanilineplus 5-percentp~ogallol (by 80-percentturpentineplus 0-~rcent -l isobutylether 85-percentcrudeN-ethylanilineplus 15-percentfurfurylalcohol Turpenttiesaturatedwith ~-phenylenediamine 95-per~entpure N-ethytiline plus 5-percentpyrogallol(by weight)

12 NACA RM E50E16 95-percentpureN-ethylanilineplus 5-percentdi-tert-butyl peroxide(byweight) 35-percentfwd%ryl alcoholplus The followingfuels,imvestigatedwithcanmercialmixed acid, (tableii) igzdtedmore readilythan cruden-ethylanilinewith catnmercialacid at both room and subzerotemperatures: L $ 1- -d butylmercaptans 70-percentfurfurylalcoholplus 30-percentcrudeN-ethylaniline As shownbytablesi and II, crudei?-ethylemiline ignitedha more reliablemannerwith coxrmercial mixed acid thanwith the Iaboratory-prepare dmixedacid With mmmercialmixedacid (tableii) mfxed butylmercaptansand 70-percentfurfurylalcoholplus 30-percent N-ethylanilineshowedtendenciestowardshorterignition-delayintervals at subzerotemperaturesthanat roam tem~mtures Differences in the behaviorof cruden-ethylzuxtline and 70-percentfu?zfuryl aloohol plus 30-percentcrudeN-ethylanilinewith commercialmixed acidqnd the laboratory-prepared mixedacid,respectively,indicatethat sigrdficant effectson ignition-delaycharacteristicsmay be producedby small differencesin the compositionof the acids Althoughtendenciesfor ignition-delayintervalsof propellant combinationsto decreasewith decreasingtemperature(tableii) are unusual,such trendsfor 70-percentvinyl-ethylethersplus 30-peroent animne and 85-percentvinylethylethersplus 15-percentaniline, respectively,with nitricacid have been reportedin generallyunavailable GermanliteratureData of reference10 show that the reaction rate of ~seous propaneand oxygenat luw pressureincreasedwith decreasingtemperaturewithina definitetemperaturerange;suppression of chainreactionsat high temperaturesmaybe a possibleexplanation In the case of certainrocketpropellants,however,a lye- Mminarygaseous evolution(fig(b))possiblyaccentuatedat tempemturesmay disperseor eqel a portionof the propellantsfrom the reactionvesselbeforethey are completelyin contact,thereby creatingconditionsthatmay lnoreasethe ignition-delayintervals as t-heyare measured d Viscosities- The data presentedindicatethat a numberof possiblerocketfuels existthat at temperaturesas low as -40 F not only appearto ignitemore reliablywith mixedacids than cruden-ethylaniline (tablesi and II),but also (as indicatedby the kinematic-viscosity data of tableiii) are more fluid Examplesof suchftielsare mixed turpentine,pure N-ethylaniline,and 70-percentfurfurylalcoholplus 30-percentxylene Blendsof 30- and

13 NACA RM E50H peroent,5-dimethylfuranh cruden-ethylanilineand 35-peroent furfurylalooholin xylenealso showedrelativelylow viscositiesat u low tempemture b! CD U-I Applimtions - Rocket-enginestart- experiments(reference1) qualitativelysubstxmtiatesome of the resultspresented The syoradic behaviorof orudel?-ethylaniline with mixed acid at low temperatures, as observedfrom the ignition-delayexperiments,was also apparentin referenoe1 The shortignitiondelays,as detemined by thesee~eriments for mixed butylmeroaptans,70-peroentfurfurylalcoholplus 30-percentcrudeN-ethylaniltie,and comercial gum turpentinewith mixed acid as oxidant,were comfimed by the rocketstartingexperimentswhereinall thesefuels gave satisfactorystartingat low pressuresand temperatures b SUMMARY m KEsuLm The igniticm-delayintervalsof a numberof possiblerocketfuels with miti acid (nitricplus sulfuric)at subzerotemperatureswere experimentallyinvestigatedseveralfuels,which appearedto i~te more satisfactorilythan cruden-ethylaniline(monoethylaniline) at temperaturesapproximately-40 F, were investigatedat variousother temperaturesover the extendedrange of approximately80 to -40 F The followingtrendswere observed: 1 With a laboratory-mixedacid the followhg fuels, investigated over the teqerature range of approxktely 80 to -40 F, tendedto =te more -tisfactori~ than cruden-ethylaniline(fuelslistedin e~timatedorderof decrea&g ignitabllity)~ 70-peroentfurfurylalcoholplus 30-percentcrudeN-ethylaniline 63-percentfwfuryl alcoholplus 7-peroentcrudeN-ethylaniline and 10-percentmethanol 70-percentfurhryl alcoholplus 30-percentxylene 35-peroentf~uryl alcoholplus 65-percentcrudeN-ethylamiline 90--&cent comercial gum turpentineplus 10-percentpropylene oxide Pure N-ethylaniline Co3mnercial gum turpentine

14 u! -a NACA RM E50H16 Of the fuels investigatedwith mumeroial mixed acid,mixed butylmeroaptansand 70-peroentfurfuryl alcoholplus 30-peroentorude N-ethylanilm Prduced shorteraverage-ignition-delay intervalsat both room and subzerotemperaturesthan did cruden-ethylaniline [ I t 1 LewisFlightEropulsion Laboratory, NationalAdvisoryCommitteefor Aeronautics, Cleveland,Ohio 1 Iadanyi,DezsoJ, Sloop,JohnL, Humphrey,Jack C, andhlorrell, Gerald: Startingof RooketEngineat Conditionsof Simulated AltitudeUsingCrudeMonoethylanillneand OtherFuels with Mixed Acid NACARME50D0, 1950 Noeggerath,Wolfgang: Summaryof TestingHyper- ~ goliorocketpropellantstechrep F-TR-1130-ND,ATI PattersonField),Oct 1946(Availablefrom CADO as ATI 385) 3 HhPlan,Nathan: Investigationof New LiquidFuels for Jet Propul- sion FrogRep No 10, GKU1TProjNo 1, Air CorpsJet PropRes,GALCIT,Nov 16, 1943(Availablefrcm CADOasATI 3117) 4 Cla%ke,FredricB, and Sapphgton,MerrillH: Study of the Ignition lag of SpontaneousRooketPropellantsMemo No 9-3,Jet PropIab,CIT June 15, 1947 (I%rojTU-1,ContractNo W ORD-148~(Availablefrom CADOas &I I40175) 5 Warner,B Fs Studiesin Self-ignitingLiqutdPropellants l?art1 The Measurementof IgnitionDelaysby the FallingDrop Method Wrt II Ignltim Delaysof PropellantsEased on Nitric Acid-anilineRep No 01~/47, ChemRes & BritishMOS,NOT Condit,P C: LiquidRooketFuels FinalRep, ,on, Navy ContractNOa(s)9947,CalifRes Corp (Standard011 Co Calif),Oct 31, 1949 (Availablefrom Bm Aero) 7 Kkvanagh,G M, Leffler,J E, and St John,R C: Self-Igniting Fuelsfor Use with Peroxides Rep No 8, Div In& Cooperation,MIT,July 1, 1946 (BinOral ContractNo 3Khxi-9107,Task C)

15 NACA RM E50H Aleck,B J, l?orbes,j, Healy,R, Meerbaum,S, and Rappolt, J P: Rep SPD 16, The M W ~llogg Co, Oct 1, 1947 (Bi- MonthlyRep No 1, Contraot,W ac-li3916, SupplNo ) (Availablefrom CADOas&l?I 13685) 9 Anon: Combine&BimonthlySmmary No 7 - July 0, 1948 to Aug 0, 1948 Jet mop Iab, CIT,Sept 15, 1948 Q 10 Pease,RobertN: The NegativeTempe=ture Coeffioien tin the Rate & PropaneOxiaati,culJour Am Chem SOC, VO1 60, 110 9, Sept7, 1938, pp Anon: Handbookof Chemistryand Physics,CharlesD ChemRubberPub Co 8th cd, 1944 ed

16 in40rnl ma) 1+!& ~ T3 4 % 3 -m s I Wtslo-z 6 49 w a w Hoignitim Crlde H-e*bnux, batch I&M33d d arba m ptasaimhj&oxirla I I =-PB=3nt m-de H-atiwkni33m pllm 13-pwnt dcoiml ffi-pa-cent s-~ m l&wmwl-miline ilufmyl 1- I,ShpvedCmdm HtllylEdlirm plm 70-pmWut flufvryl dachl (?%* I aolnticd s -u I,j -;; S7 a 3s i% 16 1: ; - Yo ignitim %3 40 u 43 4, 47 > 36 II7 W-pemmt 01T4e X-ethylmlllm plm lo-pm mnt J-3in0thylflUM a Ii -?!3 4, -4 a 81 in m 1 E i ,, ,: igltion m-prceut 01 dn 31-Ot&lnniulm plm 7~ ~-a3dbtaylrurm,,-3s L3 4 ; 3s m,67 m 67 Fl=daen explculca,,, I?4? 1 : l

17 , b -3 szao~ orlo- E! ~~ Omb 11-dhJndlirm pllu lo-prcwmt PYmdld (by -s s4 -?% 174 s 15 =-P etlvlauium plum 5~ Iucl (m W3-pcamnt O* -pm3e4w,4,6-trinitroro#motiol (w VdM -s Bpndlo Sprdla aultim 40 Bpvuc iedtial Sporauo lgniuotl pment O* 11thpilh y lo-pmmnt -m W %-P- Olac S-peraent M1-phoum (by mht) Spat dio Ignltica BJm-nMa i1utim -40 8pm ulio I&Jibim =-wlmut Crmla md41mum plau 5-PWU di-kaa butgl porofi~ (Iv -al Yo ipitlm s s G

18 TAELl I - C0UZUIWB muuucwmmmxf-muram msma7, 0mm3LAmWmm PmWKa D MI=TJ AOID 4X VARIOE Ember AYerwP Lgaitinl+& Intsrral =s= 0 Oratmre (Fmm tw-d ( m Mfniim= BmeJk8 95-pOmwt Oz n&ezi-etbyladllna pills pOrcOnt piario acid (L7 t) fla-plmemt Cmld3H*bliliu plus -36 dic ieniticm -pement B1mimn ethodde (by -Z&) m-pacat mnie 11-O*hllliae pha Fbde!3s Eqk3iom 70-pelwlrt turpentilm Pure Ii-0thpanf1m d0-s 1&lo-3 8WO : % 6S 50 s-peiwirt pum plum 5 -s pero8nt pymwud (Lv weight) %-percent pm H-etbybnilizw plus Q p6rcent rasardml (by Wisht) 65*mmt pm-e 1, ! 5-parcmt pal-cdlie (by Wdght) II,1 Pmm Efl-dietbylmillzm -36 ~ 153 r alcohol -s3 Z&lo+ 56x10-3 * pmwut mrruryl , 100 a S&pa-cent Xylmn 5-6 lea & S-perwnt nlrfluyl aldbal *IW u 101 E5 -pmmlt Xylem Iylwm -s Ho ignition ) -,,7s ? lb

19 ,, en c id gum turpentine ~0-3 7s 54 s 99xlo-3 m xlo-3 61 m 44 9B-pemellt tm pmtim plus -proent ~lem oxide 3 -m pxdic flmnlesa al-d arplcoimo 95-pOrOOnt s -p8rmut 03iae m-pelwlt IJ)-pfmant propjhm rdda : m ~~Rlo-prcmt $-dimthylnman -a p0mli0 ignitilm 70-pm3mt turpmrtim pcllm m-pm-mnt &dlm0thylfhrml md lo-iemallt pmpylono CajAa -m prOmt tarplntino plrm 15-pramt +5-dhOthylftmn end 15-paremt Cdde 4-40 Bpom6ic d -MO esplcalolm 4bpwut tmpmtine pm lo-pwmtt &61nethylmun and lo-porcmlt Juqq lem dae s porwnt ~ NJ= Ui-pemmlt &dim0*lfwrm mud 10~ Tinyl Imbntyl ether a -s Flmelma expladcm 60-- tmpmtim pm m-polmut TinJl OtJlm s Ilz nnmlms rzplmiom v P -1

20 1- rw 1 TABLE II - ~ IOHITION-IIKL4Y lm!l!a W mvmalfoeis wrrhcommcialkm3d ACID AT VARIO0 TEWERATORES (percent Fuel by olnw) lumber of?irings lverage xmperamre (%) I,gition-delay interval (see) Minimum Mexiilmm bometrlc average I Crude H-etlwlanilhe e X10-3 L xlo OX1O a L5 L percent furfuryl alcohol plus 30-percent crude l!-ethylanilfne ~ Mxed butyl mmcaptan6, ;97 ; E &LimonBne I (d (b) % 119 (a) (b) L06 (a) (b) %0 ignltien %poradlc Ignition

21 NACA BME50H16 19 Fuel Kinematic Specific (yercentby volwne) vlr3co13ity gravitys% at -40 F room tem- (centistokes) perature, CrudeN-ethylaniline 90 Mixed butylmercaptans lo3a a Commercialgum turpentine percentfurfurylalcoholplus 9 g6b 65-percentxylene 70-percentfurfurylalcoholplus 51 losb 30-percentxylene 50-percent,5dimethylfuran plus U percent crude N-ethylanillne 30-percent,5-dimethylfursa plus 0 g5b 70-percent crude N-ethylaniline Pure I i-ethylaniline 44 96C 63-yercent furfuryl alcohol plus 7-percent crude N-et~l~line ad 15 losb 10-percent methanol E-percent furfuryl alcohol plus 130 ggb 85-percent crude N-ethylaniline 35-percent furfuryl alcohol plus b 65-percent crude N-ethylaniline 70-percent furfuryl alcohol plus 8 108b 30-percent crude N-ethylaniline Furfuryl alcohol 4 113C adata from reference6 %stimated from data of reference11 I cdatafrom reference11

22 0 NACA RM E50H16 -Weighti +lrqger -pin 3 - -Guide tube, 0000, &o&fic 0000 ;!??ter 0000 ~F1ameshield D L Oscillator \ II b Electronic 3 relayamplifler Y + - t 1 { Pump tyre Pho%oelevtric piokup Unit J t -Ice h - - = - - FQWM 1 - Ap~ratua for deteminat ion of spontu,ous igiition-delay Interval of rooket fuel-oxidant combination ativarioue initial temlwraturee - * = b

23 NACA RM E50H16, 1 Time,sea o (a) Inert liquids (b) 70-percent furfuryl alcehol plus 30-percent crude N-ethylaniline with oommeroial - - u- - =5= C5160 (o)orude N-ethylanllhe with conmwrcial mixe~acid Fkure - Positive enlargements from framea of high-speed silhouette motion pictures ;howhg behavior of In& liquids and rcake% pro~lla& at room tem~ratu-during first 0003 seoonilof timed occvrre& saw t5zceafter ~ Pliminary nonbumxlng reactions ehcn% ), >, -

24 NACA RM E50H I 1 I I I I L awl 700 () O Crude N-ethylanlllne! u n [U-~=GUAU -----* AU-A *--*, LUJJ --7 =?laohol phls 30-percent crude N-ethylanillne (fresh solution) ++ n # o \ \ 0 0 ~ o o, 100 c1 lrl r c \\n c) o o 0 u -1 -D i ~n #l g lc Temperature, % Figure 3 - Compsrlaon of Ignition-delay inkervals of crude N-ethylanlMne and 70-peroent furfuryl aloohol plus 30-peroent crude N-ethylaniline with laboratoryprepered mixed acid as functions of temperature KI S5 -i