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A)<:eJ. T. lviattsvo. 29 M.arch 1973

Bonney: It's Iv1art:h 29 and '.ve're i .'lterviewi !1g Axel lVlaUson \','h o £1ad been at. tbe '!""angley Re~:ea 1'ch Center for 80D;ething over 30 years. Mr. 1,,1attson would you sta.r': out, plc~ast:~, l)y tc;Uinz us h uv,f yOLl becarne interested i.rA 1"11e NACP_ a'l d wh.:!n you carne to \,.'ork for the l...Jal:: and \vhat you fir st did.

MaU::;on: Ok, WaH. I becanle intercsten in the NAC A becau l:Je as I went to Norlh Carolina ;)t 2l:C l<.1king Mec11aJlic2.l Engineering A .. e ron'lutic al Option , one of the books that vie used i n ;=t.erodynanlics \V cUI F::. D. V/oodls book which wa.s just out at thc:.t tinK . It was t~)e firs t: edition . In. wo:r\~ng so.rne of those problen1s, you were <.!lwc:~ y.~ referencing - - he l'c fcTcncerJ very heavi1.y to NACA 2.nd th e ir w o r!:.:. Li. \c. when yo\'i. ha(~ c, pro~)lcll1 dealing v/ith the perfor;r,v.ncc: 0 ';:- the c: l c~ ~'acj:eri ::, U cs of it propeHC:.'T. o r f)OlYJethin ;:; like this, 'Nhy you b.a d to L.ese the CUI' 'Ve s that, as you. lcncIJ.', wel'e NACA cievelopcd cUJ.'V(~ S f rorD t b('~ jx rc[;earc11 . Ylell, iL's kind cf interesting because that Lrst ecliii on W;:l..S p r etty n l '..lch J.Ctckin ~ , I don: (; knuV/ \ '111 0 ever edited the thing, but jl: vias just full of a ll kinds (.If (~rrol'S,

and SOlYJ (! of th c chaJ.-ts thal w e h ad t o 1.!~; C to wor;<. t}Je pt·obl"..! l1's ::'n that book, VIC found that we had to exf ·'.-aroJ ate about .. - way of.( the p£'gc sorncplE!.ce to get the anHwers. B ut, al1),\v;::;, y, tll al. was the thing. Cine ()f

t h<:: thi ngs Lh o.t 1 ,\-vas interestcc; in goillZ 1:0 f;chool was not acrodyn i:\.~~, j c~·.

per se, but it -- I was inlercst(;(; in eng ines, ai r craft. engines, Ijnd oJ becau~:)c 0: Tl1y backgl'ol:ncL d Ul'l !:g rYly !1 ir,h school c] ;:lYS 1 wa.l, ver y J'(lUC~,

in t.E:.:resteu in 3utoD1obil es ':.1. nd (:h ;),t. s ort o£ tLing . ::;0, I W~H; - - in Lno L a h ['hat was one of the thi ngs ., if I ever did an~ri..bing !ai rly weU, why i t \V,',[; foolillg aroul1.d witll en g ines and b;..: ing part of the Lab C.t sC:lool w her.e \v e h ;::.c1 a l it tle engjne 12..h of old Liberty engines 2..nd that sort of thi n g .

Nt; Ye s. D~rnam.om cle:r.· t e s ts o f engines cl nd I just ~Loved hoo~f,illg tha t: sort of Ching '1)) d .W] evr..hl; lting it. Onc of the l' Cf) CCl rch .... c} DJi.\jOJ.'

j' (! S('. 3 J: ch -- c.ffo :-t ur an onts tandin g rt!:::earch e ffort l'ca.l1y thaL 112.p;:-)CJW '.~

a t tlJ ; l t tin'1e CI t NACA Langley Aeronauti c al Laborat ory Vias worL G.O!le on Ute dctoncl.tion pl, (..ol en.., -- r:ngincs. TI),j s h ad to du with the flall1c !)rop;lgalion in ~;j. d e tl'c cyLnd(-; rs. What t:1Cy deve l oped -- (1)(:': J', NACA .. -developed 0.t th e tirne W2, S a t echnic!uc of taking veryvcry high sp:~ed , pictl..ll e s of the v.ctu21 fJ.arrlc frOln i gniti.on r i ght on tllTough until .C! xh~.i.u[;-t~· •. ~ of the flame propaga t i on i ns i.de th e cylinders, a nd !:lO that: rec:d.ly got rne excHcd a nd th at's whY' I b a sic all y knew about r,rAC!L So, ::~t the thnc 1 took wh ?. t I found out waf:' th e 12.st Civil Ser.\· .i ce E x a n: - -. LJlcrC were three of us . There were only 12 laking t'1e Aeronautical Opti on at NC S t D.te a t thc:'tin1c. .

B: What year was thi.s?

M: This was in J.939, 1940. I believe in 1939 was the la st exam and although it. ' s easy now to make a confes~:; ion, of t1.1C thl'ec of us who took jt two of them failed a!1d I passed, but I p2.sscd wjth 73.

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B: 70 was pa ssing.

M: 70 was passing DO 1: just passed. The y made 60 something or other and they were offered j obs imm e diat81y. Now, jobs were hard to get at that particular tirne. They we: r en't easy to corn e by and they got job s immediately - - government jobs and were called engineering - - what was it - - engineering aide, I believe. AnY·'N a y. it was an $ 1800 .i ob and a junior engineer was ~;2000 a yea}'. A n d, so I didn't hear from. that and I went up and work e d at Republic a whil e while I finished, and stayed there. So, finally throu e h t h e war e ffort a nd what not , h.istory will indicate that the Civil Service commi ssi on, the dern a nd for engineers increased at a very rapid rate c~nd they got down in the cracker barrel and reached down far enough and the y fin a lly plucked rne out as a 73 with an aeronautic al option. So, N AC.A, being alDo despe r a te to get people a t the tin1e , they allowed rrJe to COTTl e to Langley.

B: And this was in '41 or '42?

M: Well, I caI'n.e actuaHy in ' 41 April of '41.

B: What did you get put to doi.ng at Langl e y?

1',11:: Vrell, that was interesting . I c. a me here, ~;howccl up, got the usual tclegrarn that was sjgncd out fl'orn K ernbl c .Jc,hnson, sa ying would you accept a probationary a.ppointnlC nt to the .L a ngley Mernor ial -- I Hlight add to that, while:r was at school I had a f ri e nd in Nc\vport News and I visited wit.h hiI'll and I CaGle i nt o the :lr C:l "i.::t ab out J.938 am: I C<lrnc o'...!t and looked at Langley F i. eld a n d they w er e building th e 19-foot tunnel at the tirne. So, I was (JUite e x c i t e d all ~he way alon g aLw,lt comin g to this p a rt of the country. It was like rny h orne t o\.vn. Therl';) was water all a routld and I ju s t f c H at horne a nd ev e rything was just great. It was Jdnd of country a nd I ' rn basi -:cllly a coun.try boy and so anyway I cani e at that tirne. I've forg o tten wh .::tl~

13: 'Nell, th e quer.·l!.iol1 was , w h a t did the )r p ut you to doing ?

M : Wh (~l did they pu t TIl e to doi ng . \V e ll, I showed up here and the firf3t thinG J. got an intcrv i e \1J w ith E lton Miller who was the Chief of Aerodynamics and he .looked ove r !n y exarr~in::ltion and rny transcript which wasn 't so great but he pointe d ou t a f e w things. He says, well, he says you look like YOU 'l-C prett y g ood a t n , atb and 1:.8 says it looks like you -- he says, ':clo you lik e t o Wtll·k w ith your hands?" And, I saiu, I!Oh, sure. I love to wor k with m y hanus." 1-{e said, '111m going to assign you to the 8-foot Hi gh-Speed tun ne l uncleI' John Stack. I' And I piped up and said "1m!: I didJllt corne to work in a wind tunnel. I canl.e to work on ·engines. " He said, 'IVlell, I'n! s orry about that. vVe don't need you there. As a D1atter of fa ct, ",/e ' re going to rnove tllat to Lewis . We 'r e pla.nning that. Vle're Tn.oving it aw ay_ I' I donlt think he told me Lewi s at the time.

B: It hadn't been dedicated as Lewj s yet.

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M: But, he said \ve' re D, ovi ng that out and we need you in the wind 'tunnel, and do YOl: want to w ork in the vvind tunnel 0 -':' d onlt y ou? j~nd I said "yes, si r. II SO, down we went and I nlet J ohn St3.ck and started working for hir.:,-] with a 6 - n'lonth p robationar y appointm ent.

B: ,And you hit it off ri ght to begin with.

M: Well, I donlt know. ! was kind of intere s tin g. He asked :me ... one of the lnajOl" progral'DS th a t he, or the L a boratory, was intereste d in, h ad at the t hne , 'what they called a propelle r ernergency p rog rcml . T11e emerge ncy \vas that to do something about increasing the high speed efficiency of propellers ... and so Stack was very n,,) llcb interested i n that and they had constru cte d a fairly sophisticat ed dynanlometer to fi:: in the 8 - foot tunncl.

B: Explain a little mar c 2.bout what you mean by irnprove the propell er s.

M: Wen, as you increase the speed of an .:drcraft -_. a propeller .. dri're n ai rpl a ne -- you ge t finaUy to the point where the tip .speed of the propeller exceeds the speed of SOlEld and whe n this l1 appen s you ge t cOll."l pre ss ability effec t s o c currjng on the propeller, and ther e for 2 the effici e ncy of the arn ou nt of thrust for a give n amount of horsepow e r decrea s es and the y wel'(! tryi ng -- the probl e rn W<lS to confi gure the propellers\vith air f oiJ. sc cl'ion confi g uration and aspe ct l'e:.tio and all of those thin gs , was the probl e m at that time.

B: To increase the spe e d and ",~ till be efficient?

}v1: Hight. So, that in han w ould increase th e spee d of the ai rpla ne and allow it to operat e efficiently at hi ghe r speeds . Of course, that i s th e so~called sv~ed barrier as far as propeller-driven aircraft is cone e rned. So that's '- - I rem en") be l' hinl a ski n g m, e in the interview, he !lai d , !'w hai. do yOIl k n.ow· ctl)out propellers ? II 1 s<l.i d, IIWe ll, I know th a t 1Ley GO on th e frf.)J"l of an ai1'[.>1a1'1e . II But , se riOl::s ly, I did tell hilYl a little -- wh a t: little _ .. I cUd k n ow , whi ch wasn 't very nluch, b ecause as 1 sa:id, 1 was rnore interc~o tC! d in the engines than I was )11. th e ael'O­d ynan"1 ics, a nd NC State (li.t~ n't have th e b est aeronautic cd. school i n th e world,. and propelle r aerc)dynamics is a pretty complic a ted thing and I just -- I don ' t thinl< hi s first i mpress ion of rr:e was well he didn ' t think too much of m y ability, I think. But, he told 11l e inimediately well, how about rep o rtin g to John Becker, and John Becker was his assis t ant: a t the tiJl'c -- Assistant S ection head. The y ' ve eot a t es t in the wind tunnel. You go dO\,vn ther e and help hi l'!1. . So, that ' s what I did.

B: And what was the expcrimen!:?

_ " M: It had to do v'lith the bomber confi gurations. There were three bombers in com,petition a t the time . The re was the B-29, the B-32 and the 13-33.

B: Who de signed the B··33?

M: Tha t W2.S Martin. and thc~t "vas the one in the wind tunnel a nd that vIas the clunker of fhe thr ee . So, anyway, we started. ! was assigned to help out on that projec t a n o. then alm os t i-fY1m~ diately I guess I sta:cted l earning -- 1. deciu ec1 to learn a11 I c ould about the wind tunnel, itself, because I thou ght I could 1e<..r n that , so I l earne d all about the drive motOl', and I l earned about the fans, and I learned to re a lly opel'ate a winu tunne l, and so I bec<!.n~e a pr e tt y g ood wind tun n e l ope ratol". But, then I w as gi ver;. an assig.rJment to -- we llad this B-33 configuration -­our rn e thod of ge ttin.g c1.r<l.g increme nts, why we would have the wing, th e n we \vou l d add th":! fuselage , and the n you would a.dd th e nacelle sand then you would add thi~; and th a t and thCXl you 'd ge t these dra g increm e nts and th at would be part of your drag evalu ation. \Vell, I w a s give n an assi gm:'lcnt - - St ack call ed me ir" and he says "I-ley, come on. I've got an assigmn ent. Come on \vi t h rne. We ' re going over to the Air Forc e Liaison Office." And, I l~ad no idea wha t it was all about. VIe went

.over the re. This was Col. Gl'een Vill a was the Air _Force Liaison Office r at the time C'.f'.id M r . R. ache- a nd we met w i th the m and the y had the prohlern was , wh a-:: was the drag of a so-c a lled 'V ega turr e t and this was essenti ally a sph cric 3.l dOTTl e th a t: they were thinkin E~ about th a t w as completely 360-de gree , \v e ll the enti re azi.nlUth really, th a t they would DJount on bornbers. B ut, they had n o idea how rnueh this cost then, in ped'ormanee. So, they wa.nte-d th e dra g of th ese thin g s . So, I took the dr awings and rny job \vas to ta.lee the drawings a nd n-lake a rnodel of t~1is so-calle d V ega turret, rnouDt it on this w in g Iu sel ae e wh i ch was basic al l)r the B-33 strea,mlined - - didll' t have nacelles - - a nd I was to ge t the clr <lg i ncrement caused by these nace lles , which I did , a nd wrote a repol't~ and pro\/ed tha t l arge tur r et;.; have more drag than l ittl e turrets.

B: H ey, very g ood, Axel, ve ry good. vVas it soon afte r that you started working on the P-3H dive br 3.kes ?

M: Oh, y e s. That was p retty soon after. Thi.ngs wer e going at a pr e tty r a pid pace at nH~ lirne , a nd I remember the P-38 was one of the fil's t a irc raft that v,,' (> h::td that had t he capability in a dive _ .. th at had . enou g h power ,Hid w a s he avy enough so that in a dive it could get very c) ose to - - w e ll, it coul<.1 exce e d i ts cri tic a l s p ee d by a sizeable mar gin. V1h o l I nlean by critical s p ee d j s that criti cal s p ee d b e ing define d as when you fir st ge l ove r the surface of the WL1 g fo r exam pI e , or over some part of the aircr aft. reach the speed of sound . The local velocity reaches the speed of sound, and you get a flow breakdown. Well, it had the capability of doing thi s and s o in the war s i tuation that ' s v;;hat happene d. The y got in dives and the y g ot the so - called com pressibility effe cts and they got the tuck under, and they got the locking , of ineffectiveness of the controls, and so forth, so the pilot h a d noth ing better -- he ju st had - - h e just c Oi.lldn't pull out of the dive. That was the problem. a nd that was the m .ajor problen~. Th a t was A. Number 1 problenl , what to do about this. So, · everyone s tarted working on it and we learned a l ot , and one of the devices that we carne up with was a so­c a lled di ve recovery flap. A sm all flap mounted on the - - at the propel' place.

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B: Where was that?

M: It was norrnally -- it turned out to be a bout 300/0 of the chord on the inboard section of the a irpl a ne. A sm a J.l flap that ,-,.;as probabl.y about 5% of th e "\dng s pan , ·;:hat y ou could ju s t flip O'_lt to an angle that we detern,ined wc~s the p rope r c.ngl e , so it w a s just a b2-ng banl,} situation, and so when the pilot g ot into a cl ive , he could flip a switch and pop this dive recovery flap, and the airpl a n e would pull up arld corne out of the dive.

B: Who suggested this solution ? Do y ou r e call?

M: Well, like all things th a t I wa s ever inv olved with, it's pretty hard to say. 'vile had spoilers. It kind of was involve d inrny way of thinking, bec a use ·\ve tried, wc knew th e w i ng \vas s p oil e d. That ir:J, the aero­dynamic flow was spoil e d by the s e c ompre s s ibility effe cts on the upper surface, so the basic id e a w a s \\/e11 , we c a n't do IYluch about that. That's nature, but Hlaybe we sh ould sp oil the fl ow on th (! under surface of the wing , and 1.:11e1'e.fo1' e you would then c c (: a b alance or a conl. pensating effect, and you would n 't hav e thi s s tr ong t cnd ency tu dive and that you could get SOll.' C -- exe c ut e corn e - - lift ana .s till g e t r e co·ve ry. In other w ords, and so then w e tri e d sp oil e r s . I don' t k now , ·;:~s far as lin, conce rned, it was a t ean, e ffort '.vith S t ack k ind uf running the show, but, heck, we just tried everything ViC c ou ld. J3ut , I think th:lt ","'as the b asic idea, probably - - I don 'j; le l ow \-\l h o· it w a s , I can't ren.·wrnb er. I never even thought about th a t.

B: Well, it ' s easy to convince you rself th at th~ solution was a fairly obvious one. It was how to do it s o it w o r l:: e d best that was r eally the probl E";m.

M : Yes. We did, havi Eg the v,ti nd t unn e l, w e rn2.d e p a r,wn e tric studies. We d e l:e rminc d what an[~ ·l ('! a nd h ow long it s h oul d be a nd v;hat its chord Wa S f whal it d phy s i cal. ~i i z e should b e and 211 Chat.

B: T hfl ll v"h at d i d y ou Ge t put on?

Iv1. : Well, th e n I g ot Dry" ow n. ,\'Jell, a bout tl1C tiTTle "\ve were working on that problem the fir s t r e port I d id I - - J i m rny Delano finally got the report writing task for the B-·33. I ll."l enti on c d that u e Iore and so I was as signed a s a co- autho r \'l i th J im n, y D e l ano a n d then Ji.-lTIITIy Delano wa s put on this propeller p r o g r am s o I g ot t hc repOl" t w rit i ng and I didn ' t know how to evaluate sorne of thi s thi n g. T his Y/ as a pr e tty somplicate d t e st on the B-33. It h a d C1 JOt of i nl e ts, very ex otic, of course v e ry high drag producing things. It was a clunk er, the re's no Cjuestior< about it. So, I decide d that John De ck e r h ad fini sh ed a report on the B-29 which was the best one and G e n e Draley had finished toge the r \vith me -- I worked with Gene Drale y o n this on the B - 32 -- so I d e cided to just compare the three. I had the clunke r. So, I just \lV'rote a report cornparing the three. Well, this cau sed quite a stir, b e cause for the first time in NACA they were putti ng out a repo rt. They we:O:'en ' t supposed to. We weren ' t supposed to COITl p a re a n d e v aluate by comparing things.

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B: Coul d you gi ve nle a co~y of that?

1v1: My report b e came suitable for indexing or sorne thing like this.

B: Could you get rile a copy o f that ?

M : I'll t ry. I don't kr!O"\v if 1 can find it or not, Walt. I might have it. I'll t ry to do that. But, that caused quite a s tir. As a matter of fact, the whole damrl report was the catalyst of causing a lot d troubl e because Martin Corzl pany lo s t the cont rac t and only the 32 and the B··29 were awarded and the po o r fli gh t engine er -- - ·what was hi s n ame ? - - it started with a Ii W I! .. - chicf cnginc ·el- with .Marti.n -_. I can't r e rnern b er . Vvell, then we jus t g ot in -- I got i nto te s ting one n10de l a fter another and then got into the X-I which eot i rlto the research a il-plane. I tested the l1.l.odel of the X··l i n th e 8-fooL tunnel. vVe we re also developing our wind tunnel capability, and we \vere trying to get a -- to excee d th e speed of sound ·in the wind tunnel, testing Lhe transonic region, and we went to th e sH,a11 model a!'.d we used tlH, large sc ale syst·enl a nd mine was the fi rst test of u sing a threc -dinlc n slonal 511:(\11 model in the 8 - foot tunnel and <.1.s a resu.lt of th at we h ad to use U: c l a. r ge bala!'.ces w hich the relation b e tween the rnode l and the accuracy of the ba.lallce was somcllling to be de si r ed , but. we did this and. Vie k1 e'.\' '.ve had t.o go in this direction. I r e n' c!nbcl' thc fi rst tjrne ' .'i,hen t.he speed uf sound exceeded , and the n ews release c ame and Stack called us, and I had to u se !l.1.y results to prove to ·hin, that:, y es , in fact, ·Yeager tlicl exceed the s?ecd of sound . If he dove or according t o hi s flig~lt we had to make all these calculati.ons. Gene Dr a l c.y and I did this tbing, and we o.greed..

B : In other wonls, yoo had to prove th at what he h o.cl d one was possible.

l,{: Yes. ]3y using the wlncl tunnel results. But , th 2.t was kilid of a n in.tereeting exerc i s e: , Then. I did tr:.e D .. ~)58~ (li.d all sor t s of things . , Ve even put ;:\ n~an in a wind tuon.c.1. Vic had a prograrn t o ge t the bl a::; t effects of a r:03.11 and ,).,' e d id this in Coopc):ation w ith Ule Nav y. When we ·we re deveJ Op1 ng the tr;.illS on.i.c t.Ll nnel we ... of course , Lh e test secti on was vcry 11Oiny , goin~ in.to the t es1: section with slots , tllat is o penings that are r e<J ui red [or " slotted throat. In order to n , ake surveys we , I gue s s , I told Stack t]wt one o f the ways we can do it is if we c a n go 2.he ad and put our guys i n (Hving snits , and I went ove r to Fort Eustic and got briefed on diving s oits and brought divers over and we put - - got into these di vi n g s uits ancl I guess it was almost the - - well, it was kind of lik e a space suit, 1 gue s s.

B: That was bec a.us e of the compression?

11: Because of the low -- you see, the equivalent pressure inside the test section go t up to be cquivalent of about 14 to 16 thousand feet altitude, so the r equirement was, as I rCITlcITlber, was that you had -- 12, 000, I believe was the up per limit. We had t o use oxygen equiprnent and a ll of this when we we r e under te s ts. I

I I I

Matt s r.>n.

B: Well, then yon were ve"!:y intimately involved in the development of' the transonic tunnel?

M: Yes. The one, of course, who inve nted. the thing '\va s in the first test secti.on, in the first d e rnonstration of that, ,,,'as by Ray Wright and a fellow by the name of Vl ard .. .. Vernon W a.rd - - and that was on a little parasite '.vind tunnel ()££' the 16-foot tunnel.

B: We ll, J ohn Stack did get the Collier 'I'rophy for the transonic tunnel, but that was for leading the total development?

M: That's the way I see it. He came back with ideas, but as far as the analytical and experin\ental 'No r k that went into this -- and the configuration studies _ .. that was a team effort headed by John Stack.

B: Well, he had a way of taking a group of people and l eading then. into SOITle pretty good

M: We h ad the best at the tirne, i nmy estilnation. We had all the capability we neede d and the n, of course, you know once you get the origin;}.l and you se c t h at its g ot s onj e po ss ibility then you have to get down to the nitty g riLt y and wh at we di d w e d e ve l ope d the slot confi guration to give you the 811100th flow . 1 rcnlen"lb e r w h en Dryden came do\-vn the first tin1e, we show e d hy a center line p r e s sure s u rvey th at we had in fact: gone right on th.rou gh th e speeu of s ou n d, but the d j stribution of velocity in the t e st s e ction wa s n ot to be d esired. But, a nyway, this \-v as sLlch a great t~lin~ th a t j u s t to 1 c a ble t o do thi~" to d rive tb e air through the speed of ~;ound in a wind t\.~nne l. Well, Dryden carne dow!l and we ':I.' e re, I l·cnl e .rn b t~ r, be i ng a? ol oge b c to Dr. Dryden that our distribution w a sn lt the bes t a nd wasn" t r e all y satisfactory for t e s tin g , in OUl' e v alu a tion. He s aid, don it b e di s courag ed, you lll ge t tho s e. Y ou TY1ac.lc th e nle,jor bre a k Uu-ou gh . I-I e said, th a t w ill cnme and that l s the way it work e d. 'N e de si g ne d . all d iHe rent slot configurations t11at we could put in a nd ou t a nd , I,.' C ran ;:Ln el ""ve J' a n nigl1t and d a y until we l1ad a ni.ce s rnooth c1is lr ib!1 tio l1 .

B: W ell, I1ve a.lwa y- s f j gured that Dryd e n 80rnetim es has been pictured too rnuch as a very cOll ser'v'at ivc pe rson, but in (l case like this, he put his own technical reputation on the line v:hen he authorized the expenditure of sever a l millions of dollars to m odify th a t tunnel.

11: I wou l d disag re e with that in the sen se that that ha s n't been my lilnited experience with Dr. Dryd E::n. As f a r a s breaking the barriers or the frontiers of t e chnolog y, h e ,vas just 2.S bold as anyon e could be.

B: Well, he and John Stack butt e d heads, as you know, l a ter in the '50s.

M: Well, yes, but I never fully und erstood that. I got involved right in the nJiddle of one of those things , but I'll have to say that I n ever under stood why it happe ned.

Mattson Page 8

B: What one was that?

M: Well, wc'd develope d this wind tunne l, John Stack prepared --well, we had to prepare a t a lk for th e AI A A - - l A S - - anyway, and this was a very secret synl po s i u l1.1. or rn ee ti ng lh a t w a t: a p a rt of a session out in L. A. and Dryde n and D r. Goe thert a nd COl'nell and Langley --now all three of those outfi t s we r e d e velo ping 80- called transonic wind tunnels, 80 this wa.s a Sl11.TI :n ary repor t th a t w as to be delivered out there by all three of the.m .and th e session was classified a s Secr e t. Dryden wanted Stack - - told Stack, as a l1.l att e l' of fa ct, that I want you to prepare this talk, I want you to be the r e a nd I w ant y ou to present it. You are the one to represent NACA. N ow) for sorriC re as on S tack had somethin g else to do, so he called rne up and said, how about writing the report and then get it done by a c e rt a in time, a nd then COl1.le here and s e e me and we'll g o over it to g ethc l', and so f orth. So, I turned out to be co­author of this thing. I put the mate ri al to ge tb e r and g ot to ge ther with Stack and he took the In ater i a l amI h e r eally w hipped it up in shape Cl n d we had a pretty g ood :ceport. Then h e t old me " y ou'r e going out th e re to give it:." '.Vell, at tl: e titTlC I didn't knov\T 2.bout thi s and being ki nd of naive her e I go way out t o the vVest Coast w hich a t that tirn c w a s guite some distance to travel. I was in a ll th i s e li t e cornpany of Dr. Goe th e rt a nd E d s o, and so I reported tbere at t he l A S building , if you rem e n , b e r it, Walt; Hartman h a d a n oHi ce. ,

B: Yes. Ed Hartman was up on B e verly· Blvd.

M: That's right, on Beve rly B lvd. and he hc:tel a n office. So, here I repor t e d in tbi s nl ornin g or th e day b efore a nd ther e in Hartrnan's office was Dr. D r yd e n, a n d I think Sharp was the r e a nd Abc Silver s tein. And I w a lked in ther e , a nd D r. Dryden l ooke d at nlC a nd I said "1-10\'1 d o you do, Dr. D r yde n" a nd " I-l ow d o you do. Wh e r e ' s John St a ck? " I s aid, h e 's b a ck ;:;.t .L ar~gh,; y . "Vv e ll, who 1s g oin g to give l1i s paper?" I Bald, "I am. " A nd t hat r ea lly put hhn out. H e reall y got kind of {u rion s a b out tb a t, andl-Ja rhnan called t o fin d out w h e r e John St a c k was and of cour se I w as li s t e nin g to all thi s and y ou can irrla gine how I felt.

B: Your confidence f a ctor w as g oing dow n pretty fas t .

M: Oh, :my goodness. You know, it w as a terrible thing for me, but I never fully und erstood 'wh a t the confli ct w as b e twe e}'l the hvo, but nevertheless I gave the p a p e r and I ::-crnern b e r b e ing cxtrcrnely nervous and I rem.ember doing w e ll t hou gh I wa s n ervou s , and I rem.ernber Sh a rp and Smitty DeFr a nce a nd a ll the NACA hi e r a rchy w ere in the front rO\v to see 110W this guy und e r the se cil"cu·ms tanc e s wa D going to perfonn and I'll never forget that episode as long a s I live.

B: Do you have a copy of that paper?

M.: Yes, I think so.

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Mattson Pag(; 9

13: it d like that one too, A"'{el. So, you got two paper s you're going to get me.

M:: I'll try to get them., Walt. I don't know where they are. You know I gave so much of this to M~. 1t . I don't have too much left. I used to know where I could pu t my hands on these thingn , out I'll try to ge t them . And, then, of course, we ceve loped the transonic wind tunnel and the n ext th ing that happ e n ed to u s was, Dick i,Vhitcornb developed the area rule.

B: H e w a s wor k.ing for y ou Ctt that time.

lvr. : Working for me at the tirne and we we r e worki ng together, I guess. I was supplyi 1!g him with aU the support he could ge t, and he was ju st trying to do son"o.cthing 2.nci that was a very interes ting thing on the way th a t happened. It was a very time ly thing also. You prob a bly know as Jnuch ab<.JUt th a t as I do.

B : No, I'd like t b have you run through that.

M: Basic a lly, ,Vhitcomb came up with this idea of the area distribut ion and th a t it should be the equivalent of a snlooth body area distribution, cl nd that if you h ave a wi n g on a body, you 'd s ubt ract the area £rOln the fusel~ •. [;e occ'-.1pi ed b y the wing or the cross sec ti o n. So, it \vas such a great - - we had t h e 10 2 in the tunnel at the time, a model.

B: The 102 wouJ(2n ' t g o s upersonically.

1'v1: The 102 was supposed to go supersonic , but boy, the drag r esults that VJe were getting just sho\.ved there was EO ~'(, and thi s was p,u-t of th e contract , so it \Va!> a very ily!portant point. As a nl.att e r of fact, eyeryon~"! \vas inv o]v(':cl in it a nd the compaflY was sayi n g well it's a H eyn.o;.,{s nUlnbcr ei'i.:!d a.ncl whe n they corrected -- made a correction { ()L' the nE:yJlold~> 11'JTnber . why then, they proved tbat they were ok. ·Well, there was a b i g dJscu ssi on about this Reynolds nutTlbcr -- even t od a y·, i t ' ~: not .. • ·we ll, I think eve ryone wi!o ' s been working the probJ.clll over the se year s has finally given up and says, we Hli ght ju s t as we ll t es t full·- scale and forget about that. But, we didn't ever fe e l it was a Reynolds nunlber effect, at leas t no t the n~agni tude to correct the drag as m.u ch as the COn1p al1Y was clainling. So, aL the tinle I decided that WhitcOII1 b had this ide a, and we j ust couldn 't wait. We w ent over to the s hop a nd we h a d these models built, and I was bound and clei el-Hli ned to get th at. · So, J: t old the :fellows - - we were worki ng three shifts at the time - - on the ni ght s hiH I just took it upon myself to yank that model out a nd put in this area rule model, ju st a Ettle basic wing body to try the thin g out. By damn, it worked. So, we said " Wow . Now we know how to ge t the dr ag l ow on this 102. Let's g o ahead and area rule it." So, we took that model a p art and made littl e plastic inserts and what not and are a ruled i t, and sure enough now the dr ag - - now she would yneet the p e rfornlanc e that she was supposed to rneet, and it was

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Mattson Page 10

jnteresting, thcre was .11.0 Teason why you shouldn't apply the same Reynolds r..urnber corr ection to the area rule model as the one that was not area ru led , and.if you did the d :l.'ag would have been zero. I think that was kind of funny. As a matter of .fact , that was the big selling poi nt.

B: Well, nov,' you've g ot the area rule behind you. Then what did y ou spend rn ost of your tirn e on?

M: Well, I rnight say, this is my OplnlOn, the area rule was some-thin g that _ .. one of the thing s that - - kind of sne aked by J oha. It cam e up. It was some thing we didn 't talk about. We l'e a lly didn ' t talk about it too rnuch. The idea was presented alrnost over John Stack ' s dead body, but he kind of felt - - he a llowe d u s to g o ahead a nd preSe!lt the concept at a department meeting with the id ea that BUSeri'l Ct. nrl would be there and all of the exper t s would b e there to prove that it ' s just a bunch of cr a p. The only trouble of it was when Dick presented that, that was b efor e we'd run the wind tunn el, it was only t wo d ay slate r that I yanJecd that model out, and then I Teally d).dn't have a u thority to do th at. I just did that on rnys e l£. As a matter of fact, if it h a dn't tu rned out so well and they found out that I w as running anotl1cr t es t and not conccntrating on this 102, they would h ave p1'0bably canned nle . But, at any rate, BUbernann spearheaded the defense of i t, and }1.e s ays it will worl(, 80

there n l y confidence w as pretty !50od to g o ahead, a nd put it in the tunnel. 'Nell. the point is th2.t it was somethi n~ that Stack wasn't the leader of. Oh, yes, we worke d for him like we (lid all the years, but it: \·:·asn 't an idea th a t he really and trul)f had and got the team toge th e r. It was ju s t some young whippersna ppers that got an i d e a and did it and did it at a very fortunate tinlC a nd a tinl e ly sort of ~hing. So, it: turned out vcry \ve11.1 rCJlleJ l1. bel..· h e go t so sick a nd tired , . that wa s eating hinl. very ba.d. We had a n aerodyn aroics conference the following year, I beli e v e it wa.S, iJnd rlC gave ,1 C the Lask, he s a jcl "I want you to write and dcl1 vc'r a p ape r at tll ·, ae r odyn~nn i c s confcrenc e a nd t he E; U bj (: ct i s g oing to be 'The Appli c<:Itions a nd Limih.tions of the A re a H.ule I " and h e said, "I w a nt: you to put 111at d a mn area ru l e to b ed fo r what it ' s worth. for the last ti-IDe so we don 't hee'.}' any rn.o re about this area r'-.11e. " So, I pr e par ed that p ape r. VleU, the area rule has never s topp e d. It's one of the gH!:lt things that Whitcom.b is doing today. l~o t o nly transonic, supersonic configuration and this so-called supcrcritical w i ng th9-t Whitcornu has . de velope ll, the basic thinking that goe s into that ,,<.'ent bu.ck to th at time frarne.

B: Tell me, I have a h2.zy idea about what a supercritical wing is, but how would you describe it in sirnpliest tenns'?

M: Well, the supercritical wing what makes a wing supercritical is the airfoil section.

B: Well, what does supercritical mean in that context ?

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Matts on Pag e 11

M: It sirnp1.y m ean f-. that if you have an airfoil or a wing, the critical speed is the point the f 01"lJCl!"d speed where L~c air is accelerating over the wing over the top surfac r:- . Now c ritical means that when the air acceler at e s at a gi ven forward spe e d and acce l erates over the surface of the wing, it 1'eaClle s ttt S 0)"oe point the local spee d of sound. And when this happens , you g e t a so-called shock wave which is a pressure differential -- a. very ~:harp dis c ontin'.lity· in pl'essure, and as a result of this pr e ssure increase., this discontinuity, yOIl get the flow separates over the wing. Now, on conventional sections , t11is will occur nornJally about just a little aft o f t he rr~axinlum thickness on the upper surface. So, what the super critic a l ~irfoil or su pe rcr itic a l w ing does , it has a very flat top. In othe r words, the curvatur e of the u pper surf2.ce of the wing is v e ry flat, so that when the wind fl ows over it,it becomes critical back further on th e airfoil, Iike a t a bou t 90% of the length, whereas in the previoll s , rnost-!cases , it occur s a round ITlaXin'lU1Yl. thick ness so it occurs at l e t ' s say 50% or ,1 0% or even 30% o f the chord, so the separated flow is very extensive all ove r the wi n g . But, on the super critical wing the salYle phcnOlTleX'la occurs, but it occurs back on the t:railing edge of the wing .

B: I-Iow do you g et Eft out of a super critic a l wing ? Or is that the trick of. the whole thing _ .. i f i t' s such a flat S Ul'L.i CC?

]\'1:: Well, you s till bet the lift of th e w ing .. The lift is not as much for a given angle of attack . Itl s not as gre a t as the oth er wing, but it so happe ns that wh~n yO'_~ h C'.vp. s .1'"noof:h flow, you do ge t greater lift at tho se speeLls, if you foll ow mI.':), NGw , the way you get t11C lift b a ck - - ther e is this lift loss in li ft , they have a Ettl e turning clown o f the trailing ed ge . So, in effect, they build in a fixed fl a p a nd so that \Nay they ge t the lift back on the ail-foil.

B: Well, thi s is very· l.l:;efu l.

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