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ROYAL AIRCRAFT ESTABLISHMENTFARNBOROUGH HANTS .

FLYING PERSONNEL RESEARCH COMMITTEE

EJECTION OF PILOTS FROM AIRCRAFTA REVIEW OF 'THE APPLIED PHYSIOLOGY

by

S/LDR W K STEWART, A F e

R.A.F. Institute of Aviation MedicineSEPTEMBER, 1946

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F ~ R C 6 7 1 FLYllTG PERSONl'JEL RESE i\RCH CONIIvIITTEE

EJECTION OF PILOTS FJ:WE AIRCRilFTA illiViEIV OF -THE -T&PLIEDPHYSIOLCGY_ __ ..... ----.- _ _ -.- ,. _ Y - - _ _ __, _by

S/Ldr . W. K. stewart 1 .A.F.G.R.A.F. Inst i tute of Aviation MedicineSeptember 1946

smgfJiillYGENERfili _ INTHODUCTIONPRESENT p.zQUIREiiIENT..

T O L E ~ W E _ O J ~ ~ ~ ~ C J ~ j f _ ~ i ~ ~ T I O N S _ rrHE E F J : ~ C T 8 OF iJR-J3Li ST uPON BODY-------,_._......._ _ -SUBSIDL BY CONSIDE:R.ti.TIONS--_._ _ . ~ . _ ~ _ .

Safety Harness and Related Lutomatic Devices- B. Automatic Parachute Opening Devices

.L.l..

C. Personal Equipment1. Helmet l Iask Assembly2. Clothing

J P T A L L L ~ _ I O N IN L ~ R R f J f TEDUCL.TION 0]31 TfiE P I L O ~_ ._-- _ . _ . ~ Oplil?iJUSON OF SEl ..T EJECTION iJID C j ~ : r n JETTISONlliGCONGLUSIONSRECmtTIvIENDATIONS

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F.P.R.C.671. ~ . x . T J i G . L ~ 0 r n T E L RESEARCH COI'w.viITTEE

EJECTIOn OJ: PILOTS It ROhi AIHCRA,FT,i'Tf:8VIE\Tili;1TIg &PLIED PHYS IOLOGYby

C . ILdr ,\.. stn r' - ~ ~ - . J , ' / ' I . K v,\cUlJ, A . CR.A. I n s t i t u t e of Aviat ion Medicine

SeptemlxT, 19h6G:E,1 JBRAL :Q'TTROJjVQ..T]orl

I i1o:ccec1 e j 8 c ; ~ i o n 0f a p i l o t from hi,"; a i r c r a f t has long been cons idereda poss ib le r(lUC:'llS of erf;crgenc:;T abandonment in circwnstances 'where normal

m e ; t h o d ~ 3 of e ~ ~ i t x:--c unduly dangerous or impossible. Although f igures have b8en pu11ishcd, of the percentage of successfu l escapes from heavyf)omlJ8rf1 no 2::ctens ive f- , cr ies is y e t a v a il a bl e fo:::, s ingle;-s ea te r f igh ters aDd, OJ.) a rem,11t, historie,r-) of i na b i l i t y to escape or of in jury incur red on Cf:\ cap i ng have; be Gn r l; garcluc1. 3.S i s o la t cd inc idc[lt s . :1'h8 so l c pr ov i s i onmade; to onalJlc pilot; .; to e3cape YlaS tl18 automatic j e t t i son ing of thecanopy. I t i s nCic-/ p r c j o ~ c d to add to thif3 essen t i a l f i r s t s te p t h e automatic e jec t ion ot' the ) i lo t .

InvestigELtion of a :t'ctn,J. ac--;ident in .January 1944 showed that it wa.sposs ib le for p i lo t to su f fe r v e r ~ r severe in jury to limbs or ext remi t ies ;vhen th(;[1C L i t \ ] exposed t ,u ' the slip-strL:.xl a t a high veloc i ty . Therecomm13ncl"1tion "''las n'iadc';;hat inves t iga t ion should be commenced in to thep r C l l ; : : ~ l . s o:;:--.auuergency cscarJc a t high sP\.JCQ with de ta i l ed refercnce to theu[--)c of t he: cockpi t DS a )ressurisl3ct parachute ce l l for a lti tude a i r c r a f t , for forced (; ,iuction, : \.no. f'o:c the provis ion of an automatic opening devicefor the p o . . : . ~ a c h u t c ..

A Elcctin?; r i ~ : ; ) held, 0:1. 27th Apr i l , 1 9 ~ 1 J - at the B..A.E. to examine the ~ r o b l e m , follO',7in2 Yihich 3.nD.lySGB \ i CrC Inade regarding the pos s ib i l i t y ofusing zc brrL1:.c pcu';ldr,lte 3.ncl, of the th80re t ica l f l i gh t pa th 0:;:' ' a p i l o t oncjec: t ion a t various f'orYla.rd 3pc,eds.. The conclusions vrere :

(a) t ha t [, j '1y ;, c!lcl,le of ;;lo\iling dmm the complete a i r c r a f t by means of aparachute ' ~ ) l . : : i J L 'be of l imi ted usc, .-vould requi re long term development,o.n(1. af fee t airfr31D.'..J des i";',n.(b) That an UPU3Tc1 ujL)ction v 0 1 o l ~ j , t y o f )I-C: f . p .s . should be su f f i c i en t in most C3.S Of:, :Cor tho :i?ilot; to c lea r the aeroIJlane s tr1fcture. Assumingthe coc:L:-=pit 8.110\wd [L 2 l't.Jc:;:,'avcl l,efo::,,(; at ta in ing t h i s ve loc i ty , theE"lC: c. :1 ini t ioJ . a c c e l Q l ~ a t i o n "iJould be 12:1 lI g ll (l.cting for l / lOth sec. A1011):cr t r avul '.!Quld, of Gourse , :CCdllCO the gil and incr0/;1.sc; t he t imQ ofappl ica t ion . Blm"ur tUill1cl";: (;st,j hene a lso bacm made to d c t e l ~ r n i n e the f l i gh t pa th of a Lean, 've/nen e jec ted \ri.tll the sea t from an a.:ll"'craf't. Theset o s t s , '.-/ith scale r-Lodels, have: shonll that for a p i l o t to c lea r the t a i l

' o f a I I ~ c t c o r - t ravel l ing a t 750 f . p. s . his eject ion veloci ty should notbe less t han 50 f . p. s . L:-- he and the) c,cat are frce: to par t , or 40 f . p. s . if he be a t t ached to tho scat. :urthcr, h0 lK1.Y ro t a t e in any d i rec t ion around his C.G. a t ra tes of' : } - 1 ; ~ : revs. /s0C. (Ref. I ) .

A meeting YI[jJ3 hol(1 a t }i.A.P. on 1);,.. 11. hlt . to consider escape fromhigh sp cod :"i.ircrcu't i l l genera1, and to Pl. 'C3 Gnt the phys io log ica l problemsinvolvod i n e j e ct io n of a p i l o t in ~ J a r t i c u l a r .

l l l i . . 9 J L ~ I ' : g i 1 ~

SU:Jscq.ucnt to the aho','"c n c c t i n . r ~ , a :;'1cquircment ,,;,as made tha t a l l prototype high .speed a i l ~ c r a f - c i3h311 be ;?rovidcd '\"lith means 17horcby the- 1

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pi lo t can abandon the a i rc ra f t E o.fely, the means provided taking someform of pos i t ive e jec t ion . }llor t his requirement the term t high speed Icovers a i rc ra f t capable of a t rue speed of 400 m.p. h. or more in l evelf l igh t .

This requirement may be modified a t a l a t e r date.PlffSIOLOGI9AL O N S I ~ T I _ O N S

There are two bas ic physio logica l problens; f i r s t l y , the toleranceof a p i lo t l ~ l G n seated, to accelera t ions of a high valUG and of dura t ionl / lOth sec.. approximately, when these accelerat ions are directed V ticn lJ vupTlard through the ver tebral column; secondly, the ef fec ts of a i r blas tupon tho body. In addi t ion there are numerous subsidiary factors to beconsidered in an actual emergency escape.

HT]\. iAN TOLERANCE r eo VERTIC.AL- Q.CJ;L,PHATIONSInves t iga t ions was f i r s t cOIl111lenccd on t h i s in 1944 using. a rockc t-propel led t ro l l ey mounted on a rUllvlE\Y 0:::' s t ee l r a i l s . The f ina l meanvalue reached Y BE 12 "g" which was appl ied over the f i r s t l / lOth sec.of the dlrration of the decelerat ion. These t e s t s did not represent

accul 'ately the accelera t ion t ime diagran requi red for the ac tua l eject ion ,s ince the dece le ra t ion took place over 6 ft. the t o t a l time beingapproximately 0.17 sec . , and l l ~ a c t speed 65 f .p . s . In addi t ion gravi tyacted t ransversely , but it V M thought tha t th i s could be neglectod inphysio logica l re su l t s . The f i r s t diagram in Plate I I I d e m o ~ t r a t e s the type of dece le ra t ion curve.

Follovling th is prel iminary work the to lerances to accelera t ionshave bl.:en cLoterP1ined on four tGf't r igs . Iviost of the vrork has beencar r ied out on three t e s t r igs a t the I ii:c:u,tin-Baker Aircraf t Co. lQlthese Flere incl ined a t approximately 20 0 to the ver t i ca l and the th rus twas applied to the b O ~ T as shovm in pla te 1. The seats and subjec t werepropel led along the :::, ails, baing brought to r e s t by gravi ty while downward movement yv-as prevented by the c.mgagement of levers in slots. . Theset e s t r igs have proved to be most su i tab le and up to the present theMartin-Baker Aircraf t Co have conducted hundreds of li-"c t e s t s vJ'ithoutfail lU'e of al1.y of t he equipment. The f i r s t r i g gave a IIfree"t r ave l agains t gravi ty of 20 ft. the second of 65 ft. and tho t h i rdof over 110 i t .

A four th r i g has buon used a t tho Arma.ment 11.08earch Department.Incl ined a t 50 to the ver t i ca l , it has a f ree t ravel of 30 f t . and hasbeon u.sed to inves t igate the bGhaviour of s ing le charges on the complexseat , jack ro l l e r s y s t e l ~ The use of res t ra ining gear enables chargesgiving a veloci ty of over 40 f t . soc. to be inves t iga ted but i s unsui tablefor physio logica l t e s t s above 45 f t . sec . , s ince fa i lure of the r o s t r a i n t ~ which has occurred in pract ice , vl Ould causo SGvcre in jur ies to the subjoct .

The i n i t i a l re su l t s on the fi :cst Martin-Baker r i g are shormdiagrammatical ly on pla te 11. The accelera t ion curves vere derivedfrom space-time recording by means OJ:' ' a high speed cine camera (750-1000frames/sec. ) . Only ~ p r o x i m t e values are sh01vn since th i s method isadmittedly inaccurate. The th i rd 3...."1(1 l a s t curve on pla te I I provedto be acceptable physiological ly, but the f i r s t and second curves l edto traU111e'l in some subjects .

Fol101:Ting f l igh t t r i a l s in . HDefiant l vdth the klartin-Baker in -s t a l l a t i o n in May 1945, i t vms decided t ha t the e jec t ion veloci ty shouldbe increa.s od to 60 f t . /suc . , t h i s f igure being confirmod by l a t e r f l ight

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1'HE ~ i F E C T S 0.;:: AIR BLAS1' upon Trill BODYApart from ado1luato clearance frol11 the a i rc ra f t s t ructure , a bas icrequirement for abandoning a i rc ra f t a t highspeed i s a close approach

to simultaneous exposure of a l l par ts of the body to the air-stream. Inp rac t i ce , t wil l have been noted that l / lOth seconds has been chosenfor the eject ion t ime. I t is considered that t h i s per iod issuf f i c i en t ly b r i e f and tha t no i l l - e f fec t s should ensure.

Possible in jur ies clue to cd.r prcss'U:C'e, may be summarised as fo l lows : 1. Variat ions in coeff ic ien ts of drag (CD) of dif ferent par t s o f t he

body. There i s as ye t , l i t t l e information regarding the aero-dynaE,ics of the hwnan body and in the pas t the CD of the wholebody has been arb i t ra r i ly taken to be 0.8. I t is thought tha tproper design o f t he seat , so t ha t t would act as a sp l in t , shouldpro tect personnel from in jury, but t m y be noted tha t i n j U l ~ y hasr esu l t ed from sudden exposure o f t h e arm to the s l ip -s t ream atspeeds of 200 m. p.h. or above, ( ind icated) , whils t the body remainedn the cockpit .

2. vVith a s lowexi t di f fe ren t i a l pressures m8.Y ex is t b0h7Cen mouth andthora..'C, r esu l t ing in sudden dis tens ion of t he lungs , and causinge i the r vagal s t imulat ion or eErphyserna. . German i.1Orkers havepubl ished r esu l t s of a.n inve ' :3tigation in VJhich subjec ts YlGre exposed to speeds up to 500 I\ H. (300 m . p ~ h ~ in an a i rc raf t , or810 I

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hwnan subjects . I t can be expected, however, t ha t ci rcu la tory ,and p e r h a p ~ : ; v e ~ ; t i b u l a r disturbances might ensue. From thevar ious fliL.ht t r i a l s carr ied out so f a r , a n al y si s o f c ine records

d D e ~ ; not revea l any r o t a t i on a t a grea te r l ~ a t e than 1 rev . / secondall.d i f the parachute stmv,".ze a.'1d the var ious anci l lary attachmentssuch as s t a t i c l i n 8 ~ : ; be proper ly designed, the seat and pi lo t wouldappea.r to be aerodynamically stablG unt i l the sea t and dummy aref 'al1in,; f reely . rChc use of a pi lo t- t ;ype chute , which s t ab i l i se sthe sea.t , has proved beneficial. . In the l a te s t ser ies of f l igh tt r i a l ~ ; in

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I t would appear, therefore , tha t in view of these two considerat ionst nught be benef ic ia l to consider n ~ l o y i n g the maximum ejec t ion accelerat ion "\:rhich could be normally withs tood vnthout in jury.

In fu l l development , i t is necessary to assume automatic operat ionof the device, apart from the pi lo t adopting the required posi t ion andf i r ing the cartr idge. T'his pr inciple Yvould en ta i l several a l te r a t ionsto exis t ing equipment, v i z : Safety Harness1. The int roduct ion of a combined parachute and safe ty harnesseventual ly preclude the usc of the Z type safe ty harness and t

would simplify pi lo t s dr i l l . The parachute wil l probably beconsidered as in tegra l with the seat ; t wi l l have an iner t ialock on the should0r at tachments to the sea t , and tensioning gearfor the lower abdonunal attachments.In i t i a l Yvork has been carr ied out regarding the su i t ab i l i ty of theB.5 parachute harness for use as a safe ty harness vvith the s ta t i cloading up to 1,000 lb . on the trunk. Furtherdevelopment i s being undertaken. Automatic separat ion of theharness attachments from the seat should not take place undertvvo seconds from the ejec t ion, and not unt i l the drogue-typeparachute has opened.

2. I t i s recognised tha t for high opening shocks the ideal method oft ransnut t ing the force to the body i s via the seat . I t i s onlyby th i s method tha t the load can be adequately spread, i f noshock absorbing medium can be othervvise interposed. This methodhas been suggested both by M r M a J ~ t i n and Mr. Quil ter .I f the landing be carr ied out in tb.e sea t , as Yvould have to beconsidered for an unconscious pi lo t , some modifications of thecanopy may be necessary so as to obtain maximum s t ab i l i t y withoutphysical act ion by the pi lo t . r:ehe chief advantage of th i s methodvvoulcl be an irnprovement in scat comfort by removal of the scattype parachute pack. A sui table safe ty harness v'lith r ~ s boxhas already been considered for th i s purpose. In the des ign ofany combined harness, care must be tal-een to ensure tha t separat ionof the four attachment points from the soat takes place sirrn.1ltaneously.The problem of ensuring freedom from in jury has st ll to be cons idered, but differences in drag bctvVGcn the seat and the body maybe suff ic ient to give adequate clearance.I t should be understood tha t both these methods involve unkno1imfactors and both are essent ia l ly long-term developments. I t i s to be

hoped tha t seat ejec t ion u n i t s ~ i l l be f i t t ed in a i rc raf t both re t ro - ,spect ively Lilld from the i n i t i a l dos ign s tage before tho harness development comes to f rui t ion. In i t i a l l y therefore , a safe ty harness of Z typewil l be f i t t ed and the d r i l l wi l l biJ comparable to tha t for the Germansca ts , i . c . ) manual release from the scat which, of coursc, assumesa ful ly conscious pi lo t .

Obviously re l iance on manual re lease alone YV'ill not provo 100%efficacious in cnsurinL; the safc ty of the pi lo t . Hovrever, t isessen t ia l tha t there be an over-r iding lnanual re lease from the seateven y,rith automatic separat ion

I t h&, been i.Jointed out before tho.t tho subject should be closelyres t ra ined to the back of the scat . \Yhcre methods of harness extensionarc incorporatod, th is cannot be fu l ly guaranteed, but the ef fec t of

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beinE, ejected yvith a loose haJ.."ness would be great ly minimised i f thereVlerB an. iner t ia lock, which would have to funct ion, in an upvvarddirec t ion as well as hor izonta l ly for the crash-landing case.'.

This development has been commenced by G.Q. Parachutes with regardto the decign of the sea t s . For safe ty harness other than of a combined type, the su i t ab i l i t y of the re lease box has to be reviewed,s ince re lease may have to be carr ied out under load. I t i s not knovnlat present whuther t h i s i s a problem of any importan?e.

The f ina l i sed vers ion of harness and anci l lary mechanisms cannotat present be fu l ly visual i sed and wi l l obviously depend on regular i tyof function under t es t . f any form of combined harness i s des igned,i t is obvious that d y n ~ i u c t e s t s , ei ther on the pendulum or on thehigh ,speed t rack, wi l l have to 1)e carr ied out by S } ~ Dept. and bythe H.A.P. Ins t i tu te of' Aviation l Iedicine

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I t may be useful to compare the two methods envisaged, i . e . (A)where the pi lo t s i t s on fu l l parachute, dinghy equipment (plus padding)with a combined harness which i s separated automatical ly , (B) where thepi lo t 3 i t s on. dinghy and padding, or merely padding, Ylith parachute anddinghy s tored elsewhere on the seat .3. For high al t i tude eject ion , assuming tha t s tab i l i ty is i n i t i a l ly

o n ~ l i s h e d in ei ther case by use of a small drogue parachute,t is necessary to prevent the opening of the main canopy un t i la lower a l t i tude is reached, thus ensuring maximum r a t e ofdescent through the low telTlJeraturG, lav: pressure z :nie.In met:iod (A) the pi lo t would be separated from the seat a f t e rsome seconds delqy, and thereaf ter , i f conscious, 'would not openhis m'fl i parachute unt i l a 10\1er al t i tude had beon reached.Education. wight be the pr incipal means of ensuring th i s . . If'uncon.scious, the automatic device would open his parachute at apredeterninec1 al t i tude . This "Tould enta i l the loss of s t ab i l i s a t i on Tlhicll ii.3 afforded by the drogue parachute and iilould also tendto increase dffiiser of loss of gloves, e tc . , from ro ta t ion andtumbling. In method 3) , the subject 'would descend on the drogueparachute to the lor:rer pre-se t a l t i tude but a t a somC\lhat slorlCrra t e than in methocl (A). Thereafter he TfOuld c.:i ther re leasehimself manually from the; ::. \eat or i f unconscious an automatic re leasecould be develop

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successful escape a t a very low a l t i tude than lf i th method (A).Furthermore assuminz tha t s o n ~ o f th e shock is absorbed by theseat via the attachments to the harness, the ef fec ts of theopening shock would be considerably less than i f absorbed by aharness alone, brnvever well designed. Further clar i f ica t ionsof these two systems can only be obtained by development of themechanical devices involved. I t i s rea l i sed that in tegra ldevices rnay tend to become c o m p l i c a t e d ~ but the cardinal pr incipleshould be observed that there should always be over-r iding manualoperation.COrrn:?arison of these two methods suggests the conclusion on aphysiological b ~ . i _ ~ , tha t the Martin-Baker combination of drogueparachute and cicag convertor leading to a main canopy mounted on the seat with a barometr ical ly delayed control would be the moreeff ic ien t .

Automatic Parachute Q p e n i n g L D e v i ~ Adequate safe ty for the pi lo t implios the provision of a device which

pul l s the r ip-cord of t he parachute automatical ly below a given al t i tude .Such a device has been developed by V ~ u i l t e r of G.Q.Parachutes Ltd. andi s at prGsentbeing tes ted. A wider f ie ld of applicat ion for t h i s thanrncrely in seat ejec t ion m y be envisaged. The dovice i s requi red tooperate at 200 - 400 f t . from any present a l t i tude to have safe typrovisions preventing re lease before the pi lo t has l e f t the cockpi t , to have manual over-r ide and a t ime delay- vrhich has been se t at present a t 2 s c cs . b ut which can be al tered so s to follow automatic separat ionfrom the scat .PERSONAL EQUmilENT1. H e ~ m e t _ - r n a s k as

Displacement of the oxygen mask assembly can occur under tyroconditions. (a) At a c c c ~ l c r a t i o n over 11-12 "g" downwards displacement may occurof the H-type mas I:: even wi th th e s t raps maximally t ightened.(b) German invest igators have reported loss of mask a t a i r speeds of

over 300 m p.hDevelopment of a ful l - face oj0 gen mask has been in i t i a ted but i t

i s considered that the Mal"tin-Baker schome of actuat ing the f i r ingmechanisDl DBy help to provide protec t ion against a i r blas t ef fec ts .The provision of pressur i sed breathing or pressure su i t s may be anadded complication. Emergency oxygen equipment wil l cer ta in ly becarr icd aml tho o = ~ y g e n quick-disconnect and the l il ic-Tel . quick d i s connect wi l l be used in i t i a l ly .

I t i s considered tha t for the i n i t i a l stages of t he Se rv ioe use 01'ejec t ion equipment, tho only policy '.lhich would be ef fec t ive is tout i l i s e Service oCl uipmc.:nt as far as possible. For those scats whichare f i t t ed ~ i t h Z type harness, a ~ u i c k - r o l c a s e va l l be inser ted in theNix: IV tubing between the a.ircraft and the seat . Thereafter a secondquick-relec.lsc betweent he Ivlk. V and tho short length of Mk.IV tubingwi l lsep8.1 'ate when t he sub jec t leaves the soat . Tho D r ing of t he clTICr;oncy OAJgon SYStelii wi l l be rcplac0d by a knob to whichvvil l beattached a. short s t a t i c l ine so tha t possible discontinuity of oxygensupply vrill be as br ie f as possible .

With :(\rrthcr developments of safe ty harness and automatic separat ion i t would be possible to delete one of tho quick re leases on the

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11k.IV tubing. Hm7cver, i t i s advisable at t h i s stage to considerf.urther 9-evelopments of emergency oxygen equipment since the Germanemergency se t woulc1, with some modification, appear to be of be t t e rdesign for th i s purpose. I t s nmin disadvantage i s that t does notact as an emergency se t unless :sepcu"ation from the a i rc raf t supplyoccurs and for normal high al t i tude f l igh t the R A F se t i s superiorin th i s respect .

A g ~ i n i n t e ~ 8 t i o n of quick-re lease of oxygen and Mic-Tel se t mightbe an advantage pravidea. -chat the re su l t i s not bulky and that i t dOGSnot form a loop vvhich might be caught in ejec t ion and prove disastrous.2. Clotlling

The 'addition of pro tect ive padding has been suggested for regionsof the body l i ab le to in jury on e jec t ion from c o c k ~ i t s with smal l- clearances. I t is thought that t h i s would not be regarded favourablyby pi lo t s in general 2nd so far no developmental work has been car r iedout. However, t is probably essent ia l that the pi lo t should w e a l ~ aone-piece garment. Protect ion against sudden exposure to extreme coldmay be des i rable but is di f f icu l t to achieve i f normal phys io logicalef f ic iency i n f l igh t has to be re,tained.Head Restraint

Pekarek has postulated tha t for pro tect ion of the head in crashlandings i t i s necessory to prevent forward movement of the head and back.The st ruc tura l st rength of the seat and attachments i s re-quired to meett ransverse decelerat ions of 5 gil and i t i s debatable whether t h i s valuecan be sustained physiological ly Tnthout cervical injury unless i t is ofvery br ie f duration. VD.l ious methods of head res t ra in t have been considered. Pcka.rekTs scheme i n i t i a l l y cons is ted of an attachment to theframe of a back-type parachute. An attachment to an incr t ia lock Ivitha weal..:: re t rac t ion spring ha::: also been considered and also a posi t ivelocking device through a spring loaded s l i t on the back of tho seat . Thedisadvantages inherent in such head res t ra in t are obvious and t isto be hoped tha.t i t wil l not provo nccessary.

~ r h c funct ion of the M a l ~ t i n B a k : e r head bl ind has already been considered. (3). othOl forn1.s of f ix ing have been t r i cd which f ix thoshoulder girdle and prevent forriTard mOV81 lent of he he ad during theaccelera t ion but do not prevent tbo subject from adopting a semi-crouchedpos i t ion at moment of f i r ing. \ The head blind i s the only method, a tpresent developed, ' .lhich posi t ivc ly keeps the head in contact with thehead res t throughout.

I ~ t a l l a t i o n i n _ ~ ~ _ The variouc.; aSlJects of th is invcs t igat ion demand cent ra l co-ordinat ion

for sa t i s f ac tory progress. I t is of the greates t importance that drawingsof cockpit layouts and mock-ups of prototype aircL'aft , in which cjec t ionscats are to be f i t t ed should be inspected a t an ear ly stage . Thispol icy has'bcqn car r ied out thoroughly and t involves repeated vis i t s todif ferent a i rc ra f t firms.

Apart from physiolozical advice regarding instrument display and thegenoral seated pos i t ion i n re l a t ion to cont ro ls , adequate clearances onc jec t ion should be ensured so tha t injury wil l not ensue from s t r ik ingcockpit pro;jections.

l \ ~ o r a n t has dc}:,ived data :i'rolD mcasuXQIl1cnts of a large number ofpi lo t s n re l a t ion to the irnpo:L'tant Gockpit dimensions (Ref.6). 1'he

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th igh length and the shoulder breadth should have adequate clearancethroughout the en t i r e dis t r ibu t ion range s ince in jury to knees, fee tshoulders or arms may occur in coch.""pits of small f ron ta l area and ofnormal fore and af t length . According to the method of f i r ing thebreadth at the elbmvs I'lith upper arlilS held ver t i ca l ly i s a lso ofimportance and t should be noted tha t the use of hand gr ips or armr e s t s involves an increase in cockpi t breadth compared to the posi t ionwhere the arJi'.S are held centra l ly over the body. The cockpi t breadtha t the shoulder-elbow region should be 27". In jury may be causedchief ly by the gYro gunsight , the windscreen and the contro l column.From Morant 's f igures a fore and af t length of a t l eas t 33" i s necessaryfor th igh clearanco, provided tha t such a pos i t i on bo adopted tha t thefee t do not pro jec t beyond the knees. The ac tua l fore and a f t dimensionin tho cockpi t wi l l therefore Clepond on the addi t iona l dimensions ofsoa t jack and r a i l attachments and whatever padding or cushions beadded for sea t comfort .

I t i s c lea r tha t the back typ parachutos or emergency packs couldnot be used for seat o ject ion unless the designers are wil l ing to increasethe foro ancl af t dimens ions cons iderably. Tho idoa l . dimens ions andadjustments of a cockpit with an oject ion sea t have been determinede::periI,1entally. I t i s kno\'m that thol'O i s an arrangement acconunodat ingpi lo t s of a l l s izes and allowing ad o quat clearances in e joc t ion . Thes()at adjustment, which has to be para l lo l to the e jec t ion r a i l s hasa range of 5 , and the :i uddor-bar adjustment has tho w1Usually largeranf,e of 13" on an arc r i s ing as i t approachos tho pi lo t . In a l l casestho :Cect are s l i :ch t ly highor on the rUdder-bar than

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The po::;i t ion of the subjec t on the :30at i s most impor'tant inest imat inG clearances s ince it cannot be guaranteed tha t the subjec t

~ , - . r i l l have his lumber reg ion c lose ly opposed to the back of the sea t ,but tho harness wi l l to 11. large extent o1Jviate movement of the backarray froEl th2 seat .

Sarlo confusion may exis t in the i n t e rp re t a t ion of the c learancef igures . Ideal ly the f igure of 3 3 f t . for the fore and a f t dimensionshould refC':' to the d i s t a ~ l l c C behreen tho re fe rence poin t in the mid- l ineof back of the seat a t i t s , junction with the compressed sea t ingl ir ie and thc;; mic1clle; of the hor izonta l bar of the windscreen. This

m C D S l l l ~ e m e n t 3hould be taken, I . ith t h l ~ scat as i t i s leaving, the cockpi t ,and roughly paraLle l to the thighs, vll18n the knees are cle;aring theobs truc t ion of' G.C-.S. or vdnciscrecn, "lthichever pro,jocts far thes t . Theclearance mw:;t depend on the angle of ojec t ion , which i s supposed to beabout 20 0 from the ver t ica l . HoriTcver, the problem of the; clearancerequirements can b e ~ t be solved in re t rospec t ive instal lat ion..s byy:rithdrmval of sea ted subjec ts through the aper ture . These subjectsshould be of varying s izes and be f u l l y equipped with parachute; ,1':Iae:Je;st, dinp;hy ancl f ly ing clothing. All types of Germ,an a i rc ra f t f i t t e dyrith sea t e jec t ion u t i l i z e d the f'L'Ceci r a i l pos i t ion and fu r the r had nosea t adjustmcmt. In the survi,;y of B..A.l cockpi t arrangerr.ents, themajori ty so fur c:;;:mnined had f ixed r a i l s , l.jut a t l e a s t one examplehad movab18 r a i l s lind jac];;:.

Opportunity is prosented in th i s a i rc ra f t , to make prac t i ca l comparison of thc,:-=

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of the elbm}s pro ject ing in to the s l ip -s t ream when grasping the handlesof the head blind.EDUCATION OF TIill PILOT

Famil ic l r izat ion with physiological af fec t s of the accelerationsoccurs ~ t r severe e jec t ions on the t e s t r ig . Muscular s t r a insarc not f e l t in the same degree and a cer ta in degree of adapta t ionwould a-:?pec:cc to tal.::e place phys io logica l ly or psychological ly . I thas bc;en thought the re fore that for pur[Joses of educat ion a se r i es ofruns on 0.. t e s t r i g to heights of l -G .- 1 5 f t . Ivith mean maximum.o..cceleration of approximately 10 - 12 g would be more benef ic ia lthan s ing le :L Uns with the maximu.m or operat ional charges.

Even \vhen eject ion clearances are adequate - and more so when theyare l e s s tho..n could be desired - i t i s essen t i a l t ha t the pi lo t shouldfu l ly appreciate the importance of making the best movements with hisarms and legs and adopting the best s tance for e ject ion . To mill

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can be quoted.. In the f i r s t p i l o t Has involuntary e jec ted a t35,000 :f't. n.nd remo.ined conscious due to the use of the emergencyoxygen SystC1Tl. In the second. a p i lo t experiencing an explosivedecompression from 25,000 f t . to 38,000 f t . became rapicl ly unconscious, even vdth oxygen se t to 30,,000 ft. o.nd recovered a t a very1mV a l t i tude from the ensuing spin . Whilst no general i t ies can bedrawn from these ' cases it i s probalJle that the s Gcond pi lo t would nothave livecl i f the decompression had occurred at a higher a1t i tude .

Ruff h a ~ ~ s ta ted tha t one of the requirements for the developmentof seo.t eject ion in GcrI"lany Vias us cape a t these very high al t i tudesthe assumption beini; t ha t e j ec t ion could be accon:plished lillithin thetime rC[3erVe of consciousness s ince it involved minimal energy consumption on the P3X t of the p i lo t . Thi3 opinion Was obviously basedon experimental \vork: car r i ed out on animals by Lutz and -on humans

-- . by Rascher and Romberg. (Ref. B .From these ~ ~ r i m n t s the o l l ~ v i n g data are deriv.ed:

( a) The highest ' s a fe ' a l t i twle for a.n opening parachute dcscent withoutOxygC:'-l Y1ClS '42,250 f t . consciousness being recove red around 5,000 f t .

(b) The hi,:;hest ~ a l e f a l t i t u c ~ e for 0.. descent 'with open pal"'achute andYiTith o=;:ygen ~ . [ J B 58,,500 f t . r.:;covcry occurring a t an approximatea l t i tude o f 27 , ) C ~ O f t .

(c) Descent could be; accomplished "i ithout oxygen from 6 ,000 f t . vritha ClODCd p.J.rachutc ( lroe f a l l ) "i."'ccovery of consciousness occurringa t 10,000 f t .

(d) Descent couleL be rilE,do vvith oxygen frOJi . 68,250 f t . with a f ree f a l l ,c o n s c i o u s n o s : : ~ boin,:;; recovered a t ~ - 2 , O O O f t .These ClStonishin2; figuxes have lod to some confusion and 01 ar i i ' ica -

t i on is necessary s ince they 'cannot be d h ~ m i s s e d 8 3 en t i r e ly improbable.Fi r s t l y , to SOilll:' c:=tcnt they confirm the experiments which VlOre

carr ied out on animals by Lutz in Ylhich tho most in teros t ing fea ture i7asthe occurrence of pathologica l changm, in t ~ 1 e lungs. In the humane x p e r i r n e n t ~ ; severe s: ElptODS of aeroembolism occurred and i t is veryimprobable that : i : a t a l i t L 3 ~ did not re su l t contrary to tho s ta tement inthe repor t .

Secondly, t l l e ~ ; - cOl1;L"irm the corresponding R.A.P. experiments thati t Yli:l.S h i r ~ h l y unsafe to descend frOG L1-0 000 f t . ~ 7 i t h o u t oxygen and 'withparachute 0:;')8n. I t i s to be noted that hanging in a parachute harnessi s Elore conducive to death froD Cl:noxia thCln pcrforming the experimentsu i t h the s u ~ , j e c t s seated in the Chair .

Third l ] , the in.:E'LwncCJ 0:::' tho eject ion :erocodure in delaying therecovery from consciousncs,3 might be c o n 3 i d c r a ~ l c and the ef fec t ofextreme cold o.Dd g:,rration in f a l l i n ~ 3 hav8 a l l been neglected.

Cer ta in inforences c:J.Ylbo d::,:'avm from t he data even i f they be in -acceptablc as a Ylholc.;.( i ) The p ~ l r a c h u t o IYlust be yosi t i-vely prevented from opening unt i l

belo\; 20,000 f t .( i i ) Oxygen continuity i s essent ia l .

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( i i i ) Some form of p r e s s u ~ e applied to the body is necessary to aid recovery, to prevent unconsciousness and to prevent severe aeroembolisTI4

( iv ) I t vlOuld be ;; benef ic ia l to sus ta in the operiing shock o f t he parachute wi th tho pi lo t s t i l l in his seat . (v) Clothing should 1)8 retaine:;;d over the en t i r e body area to prevent

f ros tb i t e and r o s t r i ~ t i o n of c l l ~ c u l a t i o n from parachute harness should be avoided a t high a l t i tudes . :Blor lt i tudes uJ t. 0 1+-5,000 f t . presslu"'e in tho form of pressure breathing equipment 'would probably prevent unconsciousness, and up to

50,000 f t . pressure breathing eCluii)IDcmt aided by pressure on theabdomen and 10\7er limbs might be sa t i sfac tory . For a l ti tude s i n excessof 50,000 f t . t i s considered harrever tha t a pressure su i t would bee:;;ssential.

The f i r s t t rlO forms of pressurizing oqv.ipment have disadvantages ;in tha t c i r cu la t ion is ill1pedcd in the extremetios. The t h i rd type has already l)(;el1 considered as an emergency type of pressure su i t and 1 o v e l o ~ m e n t has commenced.I t 1;7i11 be b u i l t bas i ca l ly around a fu l l face mask and t mus t berecognized tha t even t h i s vhich i s but ono i tem in the su i t wil l becomplicated and di f f icu l t to produce. Assuming t ha t t he design ofa garment i s achieved, \v'hich Ylould be acceptable to the fu l l range of a:ircrevr as a picce of f ly ing c lo th ing , fu r the r development ofthe pressur is ing mechanism is necessary in order to i n f l a te su i t

and mask t o t he requis i te prcssurG rri thin 1-2 seconds.The pressur is ing equipment must be mounted on the scat nd th i s

enta i l s reduct ion of lewcage r a te from rMEk and su i t to a minimum in order to keep the bulk of the apparatus as small as possible. Manualcont ro l , as v,rcll as aut o:,natic, is essent ia l . I f a ne\7 range of oxygenequipment has to bo introduced to sa t i s fy these requirements, a Horkingprototype could not be achieved in a reasonable t ~ n e un less the pressuresu i t dovelapmcnt i s placed on the high0st pr io r i ty .

Je t t isoning of the; cabin has been postulated as the f inal and mostsui table mode of escape, both for high spoed 8.nd for high al t i tude . l.iany of i t s reQuirements are s imi lar to those of ejec t ion; e.g. arnaxllfiUID ra te of descent to 20,000 f t . avoidance of unduly high i n i t i a l dccelera t ion and an t i - ro ta t ion . .

I t has the advantage ovor ejec t ion in tha t , oxcept for m ~ ~ i m l dest ruct ion of canopy, in emergency, there is no exposure to a i r b l a s t , 'Ivhich 1'lil1 alY-IayS relnain a hazard to some degree in e jec t ion and mayvery well LJlacG a l imi t on the usefulness of the method a t very highindicated speeds. Any i n i t i a l re tent ion of pressure in t he cab in ;.-ril1undollbtedly ai 'ford the occupant or occupants an advantage against anoxia,acroerribolism and cold tha t t l i l l b8 lackin[1 in eject ion .

In the cose of oxplosive decorrpr,.)ssion, the advantage may l i e i l i ~ ~ejec t ion, but only the combination oi ' .;ircwnstances which assumes nonfunct j.on of t he e m e r g c n c ~ y pressur is ing equipment, unconsciousness of thesubject to g,round leve l , and 0. re la t ive ly high st r ik ing veloci ty of' thecabin a t ground level .

The mD.:; ;:ilmun t ime tClkon for the suparat ion of the cabin, clearancefrom the f u s l ~ o and dcvelopmont of pDrachute wi l l probably w:rrnys beJJ -

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grea te r than ejec t ion in which the subject manually operates the re lease .Thus t may. appear that fo r the minimwn height at 'Vvhich escape can benude, the advantage l i e s ' ,dth eject ion .

At p r ; ~ ~ l . m t , t he conception oi' cabin je t t i soning has been l imi ted toelnployment of one rnain narachute oiving a mean ra t e of descent of 200f t . /min. to ground l eve l ' I f th i s c1e';elopment should prove sa t i s f ac toryt i"iould bo necesc;ary to consider varying ra tes of c10scont i . e. a much

higher ra t e oZ descent dovin to 20,000 f t . and the rea f te r a very lorv ra teof d e s c ; ~ T t to ground l evel with the poss ib i l i ty of using shock absorbingdevices in order to ensure tha t an incapaci ta ted creyV' could yJithstand theshode of landing in the i r seat,s \ i th in the cabin. A much higher-escapera t e could be visual i sed fr01'11 th i s than Ilould be derived from bal ing outfrom the cabin a t an in termediate 8J.t i tude .

. ' - . , a i rc ra f t cabin and cockpit should, therefore, be visual i sed asa saZcty COlI, tho s t ructure of th i s ce l l should ideal ly remain in tac tunder a l l s t resses v/hich are IjJ(Cly to be imposed by f l i g h t emergenciesor by crash landings.The p i l o t , or aircrcr'ir, shoul . bocons idorcd as an inanimate body fromthe vio'VJ}?oint of en::uring his eventual slll"ety. Thus i t may be poss ib le

tha t a complete roc1osign of safe ty h::rrnoss and seats may be nocessary i fimmediate fa ta l injury i s to be pl:'ovented during a s t ruc tura l f a i lu re a thigh speed.

Since t is l i l ,:ely t ha t c;abin j e t t i son ing Yvi; ..l be the only mothad ofsaving l i f e during emergencies occurring at indicatod airspeeds of andgreater than 500 m p h.. i t i s cons idcred that i t s development be put onhigh pr io r i ty .

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in an] given case, i t should be the func t ion of some centra l authori ty or cornT:littee to s ta te 'vvhich system has to be insta l led . E m . Q Q / i l i ~ ~ 9 H . s

Ap;rrt fJ::'om the work already in process o r under development contract , in both seat eject ion or cabin , jet t isoning problems, the following addit ional items should be considered. . 1. Ft1.l"ther development of emergency oxygen apparatus. 2. Poss ib i l i ty of fu tu re in tegra t ion of Mic-Tel and oxygen Quick Releases. 3. Solut ion of p r o b l e r ~ of sudden exposure to extreme cold by f ly ingpersonnel in a warm environment, apart from development of pressure

sui t .4. Recognition of the importance of cabin je t t i soning. 5. Recognition of the complexity of tho problem of ensuring the safe ty of the pi lo t af te r ejection.

Rcfc:L'onces1. P 8 1 . ~ k i n G.B., R A E Technical Note No. Aoro.1618.2. Gilson, J .C. , Macdonald, A.C., stewart , W.K., }j\P.R.c.659.3. Schutze , Ursula , (1941), Luftfahrtmodizin, 5,322.4 . K nackstedt, Inves t iga t ion of tho effects of high s l ip streampressures on the human body. Memorandum report TSEAL-.3-696-740.

p.29.3.

5. Beare, - ~ . L . : D . Gilson, ,T.C., Pask, E.A., stewart , W.K., }'.p.R.o.647.6. R ~ F Ins t i tu te of AviationMedicine, F.P.R.C. on the dimensionsof a s tandard cockpit in preparation) . 7. Rosson, H., Kabat, He, Anderson, ,J.P , 1943, Arch., Neurol. Physch. ,50,510.8. Alexander, L., C.I.O.S. Report , Item 24.

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PLATE 1,2&3INVESTIGATION OFSTRUCTURAL STRENGTH OF HUMAN BODY

CENTRE Of G ~ V t T , OF HE.D(Al'I lOX'....TE)

OF CENTRE or GRAVITY OFTHE USE OF IOlESTRA1NING

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