Air & Space Smithsonian – September 2019

TheBlackArrow

designstemmed

fromBritain’s

effortstodevelopa

nuclear-capable

ballisticmissile,

beginningwiththe

BlueStreakrocket

(right),canceledin

1960,andtheBlack

Knight(left)—built

attheIsleof

Wight—which

endedin 1965 after

22 successful

launches.

gyroscope, like an airplane’s artificial horizon. If

therocketstrayedfromvertical,themovement

ofthegyroscopemoveda pairofnozzlestopush

it uprightagain.Therewasnothingdigitalinthe

entiremechanism.

ThestoryofBlackArrowgoesbackto1955,

accordingtoDougMillard,a spacehistorianand

curatoroftheaerospacedisplaysatLondon’s

ScienceMuseum,whenBritainbegana program

todevelopitsownballisticmissilecapabilities.

Britain,liketheUnitedStates,hadgottenhold

ofGermanrocketscientistsafterthewar.The

keyonewasHellmuthWalter,whohadbeen

workingona differentkindofrocketthanthe

V-2,whichusedliquidoxygentoburnitsfuel.

Instead,Walter’senginesusedhighlyunstable

hydrogenperoxide.Themosthigh-profileusehad

beenina tinyrocket-propelledinterceptor,the

MesserschmittMe 163 Komet,a strange-looking

paper dart of an aircraft, which set a world speed

recordof1,004.5kilometersanhour(623.8mph).

However,it didn’tproveitselftobeaneffective

weapon,dueinparttoitstendencytoexplode.

Hydrogenperoxideis unstable,butit hasmany

advantages.Oneis thatitsveryinstabilitymakes

it anexcellentsourceofoxygen:It justneedscat-

alyzing.“Ifyouforceperoxidethrougha stackof

silver-coatedmesh,”saysHague,“whichis whatis

doneintheseengines,it fallsapartspontaneously

intosuperheatedsteamandoxygen.”Thevolume

ofsteamitselfprovidessignificantthrust—the

BellRocketBelt,aswornbySeanConneryinthe

JamesBondfilmThunderball, waspoweredsolely

byperoxidecatalysis.

IntheWalterengines,thatsteamandoxy-

genarecombinedwithkerosene,whichignites

instantlyintheheat.“Allyouneedtodotolight

yourenginesis openthevalves,”saysHague,so

it’seasytoswitchyourenginesonandoffinspace

formaneuvering.It alsohastheadvantagethat

peroxidecanbestoredatambienttemperatures,

unlikeliquidoxygen,whichneedstobekeptbelow

itsboilingpointofminus 183 degreesCentigrade

September 2019 AIR&SPACE 65

BOTTOM LEFT: ROYAL AIRCRAFT ESTABLISHMENT; BOTTOM RIGHT: COURTESY ENGLISH HERITAGE