A SingleStage to Orbit Rocl Mitchell Bunrside Clapp* USAF Test Pilot Sclrool, Edw,ards AI;l], CaliJ'ornia 93523 iutd Maxwell W. Huntert Spaceguild,San Jose, Califorttia 95117 It ts posslbletodcslgnn practlurlslnglestageto orbl( rocket wlth non-cryogenlcpropellnnts provldcd they are sufllclently dense. Several propellant comblnatlorLswere compnred to th:rt of orygen/hSdrogen: nl(rogcrr tetroxlde/hydrazlne,oxygen/nrethane, oxygen/propane, oxygcnAU)-[, solld core nuclear/hydrogen.and hydrogcn pcroxlde/JP-s. Of thcse,hydrogen pcroxlde and JP-5, rr lrlgh-dcnsttyJct frrel,offcrs 1.79tlnrcs thc payload speciflc energJrof orygen and hydrogen. The speciflcInrpulse of HrOr/JP-s Ls335 secondswhen burned at a rnlxture rntlo of 7.35:1nnd the bulk denslty of thc propetlantsat 300 K ls 1330kg/m!. Detaltedttrerrrroclrernlcnl calcul:rllons rvere performcd to substantlatethls assumptlon,Involvlng n rockct opcratlng wlth an expanslonratlo of 180 lrr vacuunl. A dctalleddeslgn for an oxygen/hydrogen-fuelledslngle stage to orblt velrlclervas rerccompllshed assumlng hydrogen peroxldeand JP-5 wcre thc propellants. The component welghtswere classifledas voltrrnedepcndcnt (t:rnks,e.g.), surfacearea dependent(fuselagc), helght depcndent(wlrlng), dry rvclghtdeperrdent (landlng gear) and grossrvelght dependcnt(englnes and englne mount). A Newtonlan ltera(lon rvasperfornred (o detcrrnlne the dry wclght of tlrc hydrogen peroxlde/JP.Svehlcle, whlch wx 29Toless than the dry welglrtof tlre oxygen/hydrogenvehlcle. Thcre arc operatlonaladvontages to uslng hydrogenperoxlde and J['-5. 'flre propellau(s:rreboth ilqtrldsat roorll tcrrtperlrture. Hydrogcn peroxlde[s rela(ir'elylnexpenslve, avallable ln trlglrpurltS,:rnd comp:rlible rtith a rrlde r':rrlet'yof nrrrterll[s. By cutolytlcallydecomposlrrg the hydrogcn peroxlde to steanrand oxygcrrbeforc InJcctlonlrrto thc thrtrst clt:rntbcr. the JP-Scqn be lnJectedas o llgrrld lnto a hlgh tenrpcratureg:u florr. 'fhls rr Introduction we ta.kethe virJueof nrissionvelocity changeto bc 9,300 rn/s, or 30,500 ft/s. The effective exltaust The empry mass M, of. a rocket is the sunr of the velocity,which is principallya functionof the ctroice weights of the individual components: of fuel and oxidizer, is related to the more fantiliar specific inrpulse[,, by c = I,o B,u'here g i.s tlre (1) Mr= Mrtr-M,* Mr* M rns*M,rr+ M^h, accelerationof graviryat earttt'ssurface, irn{l appears in the cquationonly to convertthe units frotrt time to where Mris the massof the payload,M,is the mass velocity. Tlie nunrberr is calledthe rnassratio, trtd of th€ prope[ant tanks,M,is the massof the structurc is exponentially ser$itive to chiurges in spc'citic exclusiveof tankage,Mcar is the massof the engines, impulse.t It is also helpful to note that the nrassof M,r, is the massof the thermal protectionsystem, and propellant, M r, is the differencebetween the grcssand M^;,, is ttre misceUaneousmass. The empry mass is empty rnasses,and hencethat relatedto the grossmass M,by the relation: Mo=Mo-M, (J) = Mr(r - 1) Mo = M,' 'I'o Av (2) illustratethe intporlturtcftect of propcl- = M, € lurt densityon ovenill rocltetpertornra-nce, cor)si(lcr tlrc ca-seu'lrerc the nrtussof evcrythir)gbut thc tlutks^ in wl:ich the requred rnission vclocity chtnge is is igurored.Equlttion I becotttc:s. indicatedby Av and the effectivecxlnust vclocitl, i5 fu{, = Mpt, 11, ('i) inclicatecby c. For the singlestagc to orbit ntissiott, We ciut rc*,ritr:t-his lly defirillg a t)c\vtclnl t iustltc: rltio of thc nr&ssof thc turk 1o tltc rllitssof the +lnskuctor, Fly'ing Qualitics IJranclr. Associatc ["cllow, AIA-l\ propcllmt insirlc tirr-'turrk. With lhis sub.stitutiott, f Prcsidenu 4020 lr{oorpark, Suitc 216. Fcllorv n IAA eaualion4 bccotttes: I inclicatesthe curve on which a change irt den.sity = M, Mr, * eM, preciselybalances a conespondingopposite change in = Mpt + e(r - L)M, ''"'c (5)(q. specificinrpulse. Any propellantconrbination with a M specificirnpulse and densitytlrat ftrlls abovettrc line = o' 1-e(r - l) is likely to leadto a vehiclewith a lowcr enrp(ynrass for a givenpayload nr&ss, and thosefalling bclorvttre So, for any propellant combination, if the value of line are likely to lead to correspondingly lreavier e(r - 1) is greater than 1, the mission cannot be vehicles. performed. It is more preciseto adopt a fornrulationof Conventionally,e is taken to be a function equation 5 which includes the other cotttponentsin of the overall level of structural technology used in equationl. In general,one can classitycomponents the design. This is an oversimplification,however, to whatever level of detail is required, and then becauseof the important effects of propellant density. determinewhich of thern scale with propellant vol- Consider thc simplest case, a spherical tank. The ume, gross nr&ss,empty mass, surface area, linear dominant load in a propellanttank is imposed by the dinrension, or are invariant. A value of payload pressureP, at which the tmk operates. The walls are weight divided by empfy weight can be obtained for constrainedto a maximum operating stresso, and are any combination of propellant densiry and specific made of a material which has a density p,. The impulse. liquid inside the tank has a density p, , From these It is clear fronr the precedingdiscussion that facts it is a straightforward calculation to show that: specific impulse is not necessarilythe best figure of merit to use when assessingpropellants for the single stageto orbit mission. The nrissiongoal is to impart 3P opt g=- (6) kinetic energy to a payload. The designer must 2opr provide propellants and the hardware to managetheir storage and combustion. Accordingly, rve define a If we consider the perforrnance of liquid new figure of merit, payload specific energy,€rt , fer hydrogen and liquid oxygen as a baseline,then figure assessingpropellant utility as follows: rJ00 l,4s 1,300 H 1,200 u; g l,lm Ughter vehicles .h l,mo ! 900 E F 8@ di Heavier vehicles Specificlmpulse (s) Figure 1: 'I'radeoffs between density and sllecific irrrpulse M^, tion appears,based on this analysis,to be hydrogen cp! = ;f\, peroxide and JP-5, a common military jet fuel with tYt c relativelyhigh density. Becauseboth of thesepropel- M = o, kineticener|y of enqty nwss (7) lants are cheap and liquid at room temperature, a M, kiuetic energyof jet closer look is in order. M''(Av/c): = Historv asa M, r-[ "lHfJib':,ff::xide The expressionfor propulsive efficiency is the sanle astlrat used in Tsiolkovskij's1903 book TheExplora- Hydrogen peroxide, HrOr, was discoveredin tion of the (Jniversex,ith Reaclion Fll,irtgMachines.2 18183and has beenused commercially as a bleaching Several possible propellant conrbinations agent,pa(icularly for wool, for over a century. Its were assessed,using detailedscaling of the payload use as a propellurt datesback to World War II, when to empty m&ss ratios as discussedin the previous it rvas used to power the Me-163 Komel, whose paragraph. The results are given belorv in figure 2. engine bumed hydrogen peroxide with a mixture of It is interesting to note that nearly any propellant methanol, hydrazine, nitrous oxide, and potassium combination is superior in this figure of merit to cuprocyanide. This mixttre was extremely toxic and Oxygen/Flydrogen,which is conventionallyassumed exploded on contact with hydrogen peroxide, and the to be the only choice. The best propellantcombina- Me-163 landed in flames frequently. o() k gO h bo H 0) ra rrl () rtr &Q V) .d (! o (€x I o< 6 4 z 0 H2O2/JP-5 O2/1v{cthancO2lftcrpano O2EP-I NZO4^.rDMH OUHT NuclcarftI2 kopel Iant (Oxidizer/Fuel) Figure2: PayloadSpe'cific Energy of CandidatePropellants for SingleStage to Orbit More reccntly,HrO, has beeneffective as a Characteristics of Hydrogen Peroxicle propellantin two rocketengine progranrs. The 6,000 pound thrust AR-2 rocket engine in the NF-IM Hydrogenpe roride, rvhetrpure, is a colorless researchaircraft allorved the aircraftto reachaltitudes liquid. The nroleculeis verystable, but is sensitiveto of over 33,000nr (110,000[l) and retum to a pow- catalysisby intpurities. Consequently,the nlore pure eredlanding, setting altitude records for aircraftrvhich it is, the nrorestablc it is. In conccntrationsover 99 took off undertheir own power. Thc propellantsfor per cent,it decaysin strengt}rby le.ssthan I pcr ccnt the NF-104 rvere ordinary jet fuel for the prinrary per yeart. Its heat capacity,viscosity, iuid thenild engine,and HrO, and jet fuel for rocket flight above conductivitylnake it a betterheat tran.sfernrediunr, 17,000 m (50,000 ft). HrO, was also used as a poundfor pound,lhan jet fuel, artdalnrost as good :us nronopropellantto maintain attitude control at ex- rvater.It is avarlableconrnrercially for priccsbetrveen trenrelyhigh altitudeswhere the aerodynutriccontrols fifty centsto a dollar per kilogranr. Table I lists a were ineffective. No rocket engine-relatedenrergen- numberof propertiesof HrOrn. cies were noted during eight yearsof operation,and fuels managementwas performed using essentially Table1: Propertiesof HrO, conventional maintenance procedures and nomrally Molecularwelght 34.016 trained personnels. FreezlngPoint -0,4c The other vehicles to use I!O, as a rocket BollingPolnt 150.2C oxidizer on a continued basis were the Black Denslty(room temp) 1,442,5kg/m3 KnightlBlack Arrow seriesof launch vetriclesdevel- HeatCapaclty 2,4302kJ/kg K oped by the Royal Aircraft Establishnrent for the Vlscoslty 0.001249Nt s/nr Great Britain Ministry of Technology. The Black ThermalConductivity 563.8W/m K Knight and Black Arrow progr:rmslasted from t958 Materlalssultable for long Aluminum,tln, to 1971. In October 1971, the fourth launch of the termexposure stainlesssteel, Black Arrow placeda 120 kg (250 lb) satelliteinto a polyethylene, low polar orbit from Woomera,South Australia. The vehicle was about 13 m (43 ft) tall and 2 m (1 ft) in Hyfuogen peroxide is not toxic in the con- diameter,and its enginesdelivered a specificimpulse ventional sense,but like any oxidant, is a porverful of only 217 s (2,130 Nt sikg) for the first stage and irritant to ttre skin. Flushing rvith water is usually 265 s (2,600 Nt s&g) for the secondstage, both of sufficient to carry away the HrOr, and the resulting which bumed HrO, with kerosene.Despite these very solution poses no danger to the environment if the low perforrnancelevels, the vehicle had no trouble final concentrationof HrO, is less thiur 25 ppnt'o. achieving orbit and was not of enormoussize6. The principal hazardto preventrvhen handlingHrO, The operations procedures of the Black is the mixing or contact of hydrogen pcroxide rvith Knight and Black Arrow are interesting. The vehicles aly flammablematerial in tlre presencoof a catalyst. were a.ssembledand test-fired on the Isle of Wight, Provided that the tanks, lines, and other equipnrent and then shipped to Australia by meansof a six rveek renrain clean and never conre into contact rvith sea voyage. After arriving in Australia, they were potentially catalytic materials,HrO, can be iussafe tnrcked up an unpaved road to the launch site, rvhere and easy to handle as jet fuel". they were erected and fuelled under essentially field Detaiied thermochenricalcalculations were conditions. The structureswere unusually srurdy and performed using tabulated values of enthalpy ancl robustby rocketrystandards, and the Gamma201 and entropy and corsideringthe dissociationof exhaust 301 engineswere simple and had no advancedcon- productsfor the reaction: trols. The engineswere designedto deconrposethe hydrogenperoxide prior n (u) to fuel injection,causing safe HrO= + xCHr.r, - J'CO: iH.O and secure thernral ignition without igniters. The HrO, used was only 85 percent pure (the rest hing whereCH,.o, is the enrpiricalfonuula oi fP-5 attd1,1', water). The 26 flights in the Black Knight nrissile and ; arethe nrolefractions of the indicatedchenrical and Black Arrorv launch vehicle progri\n1sover 13 species. The results of tlese cdculations were yearshad no propulsion failures,no launch pad fr-rcs, verified by conrparingtheni rvith the rcsults of a and very low costs by the sturdards of nrost rockct dedicatedpropellant perfomrancecontputcr coder2, programsT. anil several values referenced in thc literaturel3'lt. Operational Advantages of Table2 shorvsthe re.sultsof thesecalculations for thc Hydrogen Peroxide nrixture ratio of oridizer to fuel that yields the maxi- mum value of.en, calculated fronr equation7. The experienceof the NF-104 and Black Knight/Black Arrorv programs indicates that the Tnble 2: Perfornranceof JP-S and HrOl handling of hydrogen peroxide poses no special Chamberpressure 21MPa challenges.Particularly important is the advantageof 3,000psl not having to handle cryogenic nraterials. Because Propellantmtxture ratlo the vehicle is essentiallyisothermal prior to flight, no ..,bymass 7.35 precautionsto prevent cryopunrping (such as, for ..,byvolume 4.02 example,helium bubbling)are required. The propel- Fueldenslty 850kg/mr lantsmay be storedaboard the vehicle itself, permit- 0xldlzerdenslty 1,450kg/m3 ting a quick reactioncapability. No fuel needsto be Propellantdensity 1,330kg/m3 expendedto chiJl the enginesprior to ignition, and no Nozzleexpanslon ratlo specialgases are neededto purge the fuel or oxidizer ...invacuum 180 lines. Layers of special insulation can be dispensed .,.atsea level 30 rvith, and the large diameter,heavy fuel [nes neces- Sealevel l,o 295s sa-ryto carry liquid hydrogen are reduced in weight Vacuum1,, 335s and surface area. Hydrogenperoxide can be decomposedin the presenceof a catalystto producestearn and oxygen. Thesevalues were usedto calculatethe value The reaction is: of.ert indicatedin figure 2. The value of density and HrO, HrO * + 12.961 becausethe decomposidontemperature exceeds the Orlllrrr sintering temperature for silver. For pure HrO, permanganate solutions are highly effective, as is Eqgtlor (3O) platinum. Calcium permanganate deposited on aluminum pellets to provide a reactive surface has Figure 3: Alternative Single Stage to been effective as a catalyst in the past. It is also Orbit Design possible to inject the catalyst as a liquid into the fuel stream or oxidizer sFeam, but this would require another consumable item to be provided aboard the The payloadsits in its bay at the approxinrate vehicle2o. midpoint of the vehicle. The fuel tank is in the nose Finally, the exhaustproducts of the combus- and the oxidizer tank is aft of the payload. The tion of HrO, with JP-5 are predominately 20 percent payload is located where it is to nrinirnize travel of CO, and eighty percent HrO. Less than 0.25 percent the center of gravity when the payload is removed. of the propellants are exhaustedas carbon monoxide. The vehicle is aerodynamicallystable in nose first or This propellant combination produces less carbon tail first reentry and can achieve an lift to drag ratio dioxide per unit of water vapor than conventional of 0.8,sufficient to give it aeroclynamiccrossrange of combustionof hydrocarbonswith liquid oxygen. As 600 miles2t. The thernralprotection systenr rveighs such it is more environmentallybenign, second only 1.2 poundsper squa.refoot, on average,and is con'l- to the combustion of liquid oxygen rvith liquid posedof carbory'siliconcarbide, ntetal niultirvall, and hydrogen in this respect. It avoids the release of themral blanket materials2r.The vehicle lmds tail toxic chenricalsinto the atmosphere,such as nitrogen- nrst on enginethnrst only. bearing compounds (fronr buming, for exanrple, The enginesare pressurefed. and operateiit hydrazine or nitrogen tetroxide) or halogen com- a chantberpressure of l4 MPa (2,000p.si). There are pounds (fronr solid rocket propellantsor fluoridated thirty engines,arranged in a circle aroundlhe baseof oxidizen). the vehicle. Each engine has an exparrsionratio of 18.5,but thecluster as a rvholehas an expansionratio 4, TIteLuftn,a/fe,Tlnte-Life Boolqs, Nerv York,1982 of 366. This l,ieldsa spccificinrpulsc nt launchof 289 s, and in vilcuulna valuc of 335 s. The zero- 5. TlteAerospoce Research Pilots' School,(curricrr- lcngthplug nozzlecorrfiguratiorr cAu.ses sor)le loss of unpublished),Edrviuds AFB, Cl 1969 efficiency(4.5 pcrccnt), but thc rcrlucLionin rveightis lunr handbook, [nvornblc23.Thru.st vcctoring is acconrpli.slredby All The lUorld's Aircraft, Jane'sDefense Wcekly, individualginrb:rllirrg of thc engines. Tlre tanksarc 6. 197l-72 conlpose(lof tlrc higltc.ststrcngth to rvcightnrateriirl London,UK available,Kcvlu 4924.For ail structuralconrponents, Becklake, J. The British Black Ktiglt Rocket, a rveigtrtnrargin of l5 percentrvas nraintained, along - 7. JBIS Vol. 43 p.283, July 1990 rvitir standardsafery factors for pressurevessels and No. 1 buckling. The vehiclc is designedrvith a takeoff and Ross, D.M., RocketPropulsiort tlrrustto rveightof 1.3,and crn loseup to sixengines 8. Sutton,G.P., Wiley Nerv York, t976 beforeaborting. Securcintact abort everr rvith rrrulti- Elentents,John & Sons, ple enginefailure is a key opemtionalrequirenrent for an effcctive a-ndsafe launcher. 9. Kit, B., and Evered, D.S., Rocket Propellant York, 1960 The veliicle is 56 ft long and 23 feet in Handbook, Macmillan, Nerv dianteterat (lre base. The enrpty n1ass,including der Frishx'asserund payload, is 30,0C0pounds. The gross ntass is t0. Liebntan, H, Handbucit Gustav Fischer Verlag, Jena pp 620,000pounds. It is designedfor a crew of nvo Abv,asser'-Biologie, I and an endurancc,on orbit, of four days. 7 19fl Wasserstoffsuperoxyd, 960 I l. Andrervs,D., and Sunley,H.,The Ganmn Rocket Conclusions -.- Engfnes for Black Knight,JBIS Vol. 43 No. 7, Lon- don, IJK, July 1990 A new figure of nrerit, payload specific energy,suggests that high density propellants can lead Progrant Estinnt' to lighter vehicles despite reductionsin specific 12. McBride, 8., A Contputer for tlrc Perfonnanceof RocketPropellattrs, NASA impulse. A particularlyattractive choice is hydrogen ing Lervis ResearchCenter, Cleveland, Ohio 1972 peroxideand jet fuel, rvhich has a specificinrpulse of 335 s in vacuumand a densiryof 1,330kdm'. A 13. Thompson,R.J., "High TemperatureThermody- liquid hydrogerl4iquidoxygen vehicle rvas reduced in naniics and Theoretical Performance Evaluation of rveightby 29 percentu,hen redesigned u,ith HrO, and I/te Chenistry of Propellants, JP-5. Experienceand analysissuggest no special Rocket Propellants," J., eds, Pergamon,New problems and reducedoperations costs rvhen using Penner,S.S., and Ducarme, hydrogen peroxide, An altemalive vehicle dtisign York, 1960 could provide unprecedentedlevels of perfornlance, Evaluationof Cheni' econonly,safety, and flexibility. L4. Williams, R.J.,TIteoretical cal Propellants,Prenticc-Hall, Englervood, N.J., 1963 References 15. Andrervs,D., Advantdgesof Hydrogen Peroxide - as a Rocket Oxidanr, JBIS Vol. 43 No. 7, London, UK, July 1990 1. Hill, P.G., and Peterson,C.R., I{eclnnics and Tlrentrodl'nornicsof Propulsiort, Addison-Wesley, 16. Schumb,W.C., et al, "HydrogenPeroxide," Dil'. Rcading,N{a, l.970 of tnd. Coop., Proj. 6552, Report 42, Parts I-IV, MassachusettsInst. of Tech., Canrbridge,lrlla., Sept- 2. Tsiolkovskij, K. L, The E.rplortttionof rlte Uni- Dec 1953 rerse v,itlt Reactiortt:lying I{achincs, (title trans. fronr Russian),Najutiizd:rt', Petrograd, 1903. L7. Probert,R.P., Application of Researchto Gas- Turbine ContbusliortProblents, Proccedittgs,Joint 3. I{ondbook of Cltentislt'7ro,,4 P/llsics, Cheruical Conferenceon Conrbustion,I Mech. E & ASME, RubberConrpany, Clevel:rnd, Ohio, 1975 l 985 18. Oates,G.C., Aerotltemtodypllrrirs of GasTurbine and Rocket Propulsiott, AIAA Education Series, Przemieniecki,J.S., cd., AIAA, Washington,D.C. I 988 19. Roshenorv,'V1., and Choi, H., Ileat, Moss, and Monrentunt Tronsfer, Addison-Wesley,New York, r978 20. Lervis, B., ct al, eds., Conhustion Proces.res.' IliglrSpeedAcrodynantic and Jet Propulsion,vol. II., PrincetonUniversity Press, Princeton, N.J., 1956 21. Griffin, M. D., and French,J.R., Space Vehicle Desigrr,AIAA EducationSeries, Przemieniecki, J.S., ed.,AIAA, Washington,D.C., 1991 22. Regan,F.1., Re-entry Vehicle Dyl6x7ics,AIAA Education Series, Przenrieniecki,J.S., €d., AIAA, Washington,D.C., 1986 23. Booz, D.E, and Schjlling, M.T., PIug Cluster Nozzle StudyFinal Report, NASA contractNAS8- 11023(PWA FR-1013),Marshall Spaceflight Center, 8 Sept 1964 24. Schwartz, M, M., CornpositeMaterials lland- book.,McGrarv Hill. Nerv York. 1984