--- PAGE 1 --- I • • Authority: NND927545 HEADQUARTERS AIR KATERI BL COWAND MClA/JCB/amb Wright-Patterson Air Force Base 2DjytAPH 0i948 KCIA SUBJECT, Projeot "BIOi" • TOs Chief of Staft United Statea ilr Poree Waahington 26, D. Co ATTN s Director ot Int-,lligenoe l. Thie ie an initial report on unidentified flying objecta aa direoted by Rq, USAY letter dated SO Deoember 1947, signed by General L. C. Craigie, subjeot1 •r1~Jng Diaea~. Qtarterly reports will be submitted beginning 1 July 1948. 2. Ae a reeult of thia letter, Pro~ot HT-304 was a.otiTated on 26 January 1948 and Technical Inatruotion 2185, dated 11 Pebruaiy 1948, wns published. Present ti.lea on Projeot •s10~• represent a oonaolida­ tion ot reports received directly by Hq, AMC and thoee forwa.rded by the Direotor ot Intelli gence, USAF. ~. Schedules of activities of lighted night-flying adTertising blimps have been secured a.nd crosa-oheoked at thi.a Headquarters to consider them as a possible souroe ot incident nporta. 4. Inoloaure l represents a tabulation am breakdoWll of all available reports through l February 1948. 5o The following ia a series of interesting observation• that were noted when rev19Wing the many incident 0ase11 a. Rigll rate of olimb, aa well aa the apparent a.bi li ty to remain mot1onleu or hover for a oonBiderable length of tiu o bo The objeot was described aa being oval, d1ac or 1auoer- t ehaped ~l times. o. Assooiated sound was preae?It ll tim.H o d. Reported sizes have varied from that of a 26-oent pitoe to 260 feet in diameter, and from the aise or a puraui t plane to tht ePulk of six B-29 airpl.&nea. , NND 927545 --- PAGE 2 --- .. AMC Subject, Project "SIG!i" • 2 3 APir 1948 e. »umber of objects per aighting, Objects per sighting l 2-6 6-10 over 10 Number of eightioga 77 21 8 9 t. Exhaust traile were reported 23 times. g. Speed has been eetime.ted throughout the entire range from very alow or hovering to supersonio. 6. Incloaures 2 and 5 are anlargementa of photographt taken of Incident f40o Inoloaure 4 1s an evaluation of inolosure 2 by thie Headquarters. Attention 1s iovi ted to the marked aimilari ty between incloaurea 2 ands. and inoloaure 6. Similarity also exiata between inclosures 2 and 3 and oonfigur&tiona illustre.ted in inolosure 6. 7. Representatives from tbie Headquartere visited Dr. Ining Langmuir of the P~sea.rch Laboratories. General Electric Comp&ny. Schenectady, N. Y. to discuss Project "SIGN". It was the opinion of this acienti st that prosent a.vai l!I. ble data does not encompass suffi­ ci ent information to enable a positive identific~tion to be ma.deo Dr. :.a.n&muir was relucts.nt to consider the so-called "flying discsM as a reality. However, it io be'lieved at this neadquarters that it is possible to oonstruot a low aspeot ratio airoraft that would d~pli­ oate many of the appearance and performance oharaoteriatics of reported "flyint discs~. Experts have agreed that thie would be possible through the intelligent application of boun:lary layer control. FOR THE COMMANDING GENERAL: ~Me~ 6 Inols l. Tabulation J H. M. ticC~!1. Co lone1. US&F 2. Photo Chief ot Intelli gence 3. Photo 4. Eval of Incl 2 6. Horten Parabola 6. Biology of I'lying Se.ucor 2 ~ NND 927545 --- PAGE 3 --- Incident No. Date / • Hour CONFIDENTIAL Location - N<>• Sighted Obser,ed P'rom 1 g Jul 47 0930 Muroc ilT Field, M'uroc, Calif. 2 Ground ; la g Jnl 47 0930 Muroc,Air Field, Muroc, Cali£. 2 Ground lb e Jul 47 0930 Muroc Air li'ield, li&uroc, Cali.f. 2 Ground le g Jul 47 09tl9 Muroc .lir Field, lluroc, Calif. 2 Ground ld g Jul 47 1000 lmroc Air Field, Muroc, Calif. 3 Ground le g Jul 47 1000 Uuroc A.Lr Field, itiuroc, Calif. 3 Ground 2 g Jnl 47 1200 Muroc Air Field, Mu.roe, Call!. 1 Ground ~ 7 Jul 47 1010 Iifuroc Air Field, Vuroc, Calif. 1 Ground 4 $ Jul 47 1150 Area 113, Rogers Dry Lake, Muroc l Ground Air Field, Muroc, Calif. 5 4 Jul 47 1305 ~ortland, Oregon 5 Ground 6 4 Jul 47 1305 1llli.lwaukee, Oregon 3 Grotmd 7 4 Jlll .47 1305 Portland, Oregon 1 Ground ~ 4 Jul 47 1305 Portland, Uregon 3 Ground 9 4 Jul 47 1305 Portland, Oregon undetermined wt atated 10 4 Jul 47 2004 Roi se, Idaho 5 Air ll 4 Jul 47 not stated Seattle, Xashington l r.:.r ound 12 4 Jul 47 1305 Vancouver, Washington 20-30 Ground 1~ 4 Jul 47 1400 Portland, Oregon 4 Ground 14 4 Jul 47 16}0 Portland, Oregon 1 Ground 15 4 Jul 47 1700 Portland, Oregon 3 Ground l.6 4 Jul 47 ll.00 Mount Jefferson near 4 Ground Redmon, Oregon 17 2ll. Jun 47 1500 14t. Rainier, a.shington 9 11r l!S not stated not stated Toronto, Canada 1 Ground 19 20 Oot 47 1320 Dayton, Ohio 2 Ground 20 20 Oct 47 1100 Xenia, Onio • l Ground CONFIDENTIAL NND 927545 --- PAGE 4 --- CO~FIDENTIAL e Incident No. Observed No. Date dour Location Sighted From 21 29 Jun 47 1645 Des Moines, 1owa l~ not stated 22 21 Jwi 47 about noon Spokane, ·1ashingt,on Ground 23 30 Jun 47 1745 Boise, Idaho 1 Ground 24 12 J\111 47 1&5 Weiser, Idaho 2 Ground 25 4 Jul 47 2345 Vfest Trenton, t~ . J. l Ground 26 10 Jul 47 not stated Harmon Field, Newfoundland l Ground ~ 10 Jul 47 ~ Hamon Field, bewfoundland l Ground 2g 24 Jun 47 not stated Idaho l Ground 29 23 Jun 47 not stated Bakersfield., Calif. 10 Ground 30 7 Jan 4! l ~ T Lockbourne AB, Co1umbus, Ohio 1 30a 7 Jan 4g 1925EST Lockbourne,!B, Columbus., Ohio l Oroum 30b 7 Jan 4a 1915EST Lockbourne AB, Columbus, Ohio l Ground 30c 7 Jan 4g 1940 Lockbourne il, Columbus, Ohio 1 Ground 31 mid-December early a.m. Northern Arizona l Ground 1946 32 32 not stated after dark Columbus , Ohio 1 llr 7 Jan 41! 133&.l'T,OO"' Oocbnan Field, Ky. (south of) 1 Ground 7 Jan~ l4000ST Godman Field, Ky. 1 Ground 7 Jan~ 1320CS'J.' · 0odman Field, Ky. 1 . 33c 7 Jan 4g J..420 CST 2100 from Oodman Field, Ky. 1 Ground 33d 7 Jan 4a Gedman Field, Ky. 1 Ground 33e 7 Jan 4g J..430-1600 Godman Field, Ky. 1 Ground 331' 7 Jan~ Godman Field., Ky. 1 ~ l ,l - l , 33g 7 Jan~ 11!54-19()6 lladi.eomi-1.le, Ky. ~ Ground I. 34 13 Oct 47 05}0 l4 mi1es north of Dauphin, J.lanitoba, Canada ~ Ground 35 12 Nov 41 GQ'l.Jr a.m. ticonderoga at sea (40 miles Boat south of Cape dlanco, 20 miles o£f shore) \ \ \ I CONFIDENTIAL NND 927545 --- PAGE 5 --- . DIOIDD'f ;w. - vu~FIDENTIAL lo. a...nect rra Is, 12111:. r,ooat1cm SMaatfd ,6 Jot Stated lot Stated !oilt, Idaho 1 Ground ,1 12 oot 47 1200 Oa•• Creek, Ar1■ ona 1 Qro\md ,s 10 Jun 47 lot Stated !udape1t, Bung&J"1 1 Ground ,9 9 Jlll 47 2,,0 Onnd Palla, levtoundland 5 OJ"ound 40 7 Jul 47 1600 Phoenix, Ar11ona 1 Oroun 7 Jan 48 4& 7 Jan~ 19,0 Y1la1Dgton, Ob1o 1 Orcnmd -84 7 Jan 48 1920-1950 111.111ngton, Ohio 1 ll'ound 9 Jan 48 2,00-2,15 J>aJffi 11e , ltntllolq 1 Qroimd ~ 50 10 Jan Ji8 2200 11lcSVood, In Jei-■r, One at tb11 Orouad date, PNT- 1wa17 1 ..oh 27 Deo,, JUI all at 2000 o 1oloek. 51 'Sept lf 1215 on.ao, oneon 12-15 Ground 29 Jul 47 1450 1181111 ton 11eld, Cal1torn1a 2 Oroad 52 ,,. 29 1111 •n Atter 1200 llllilton Jield, ca11tarn1a 2 Ground 53 28 Jan IJ7 1515 Lake Jllead, ore1on 5~ Air 22:50 Jorth Sea (50 ail•• troa 1 Air 54 16 Jan IJ7 tbe Dutch coa,t) BIJ'llCffl Pield, ltvtoundland l Orolll\d 55 2:, Jul 47 o,45Z --- PAGE 6 --- IAo1c1ent - -CQ~F~DENTIAL - lo. simaa Ob1enec! ?fe, 15a. us. Looat1on D:99 56 6 Jul 47 2945 1-10 Gi-oan4 57 20 lul 47 0015Z Abou-c! the BUl'aeo (at sea 1 Boat one hr. troa 874ne7, Autft11a) 58 4 Aug 47 BYeJWII Bethel, Alaska 1 Ail" 59 14 Se»t 47 055ae1T Reeter Ialand 1 ill' 60 10 Jul 47 1000 Oor4707, Canac!a 1 OPOUDCS 61 8 Sept 47 22:,0 Salt Lllce Cl tJ, Unb 12 Ground 62 8 Sept 47 22:S0~:S00 Salt Like Cit7, Utah 5 Sl'0'QP8 Ground eaoh oan- ta1D1Dg :S5~0 01:tJecta. 6:s 29 JuJ. 47 1205 can,on 1em, llontana l Ol'om:ad 64 19 Aug 47 2130 Tv1n Jalll, Idaho A.pprox. Ol'oun4 55. 65 2 Jun 47 lot stated Rehoboth Beaoh, Delevan 1 Ground 66 10 Aug 47 2100 811Yer 8pr1.ngt, Ohio l Ol'ound 67 llJ. Aug 47 1600 Placemlle, lalitornia 1 Ground 68 24 Jun 47 Hot 1tattd Cuoa4e lountaiJ:aa, 6 Ground Pwtlan4, 01-egon 69 6 Aug 47 22,0-2245 Ph1l.a4elph1a, Pa. 1 Ol'Ound 70 6 iug 47 1045 Ph1lt4elph1a, Pa. l Ol'oand 71 8 Oot 47 lot 1tatecl Laa Vega■, leYa4a 1 Ol'Ound 72 lot atate4 Jot 1tatec1 Port R1obardl0J1, Alllb 1 Ol"oand 7J 4 Aug 47 1600 Boston (101111e1 n) •••· 2 A1r 74 24 .JW'l 47 App. 1500 •t. A~IU, ftlh!ngton lot stated Ground 75 1, Aug 47 1300 saote Rl•er aaix,on, Idabo l Ground 76 1:5 Aug 47 Jlornlng Salaon Du, Ic!aho 2 Ornnd 77 :S 11117 47 1s,~ South BrookYille, Dine 10 Gl'O\IDl2 78 :,o Jun ~7 0910 JIST Oran4 ClllQ'on, AP1aoaa 2 ill' 79 Apr 47 1100 ES! R1oba0nd, V11"g1n.1a 1, other■ on Grcnmd other ooou1ona --- PAGE 7 --- coNriBcNTIAL lno1dent Jo. °'8tl"Ytd 19, em.. Looat1op SUhtn rrw 80 1 Ground 81 7 Jul 47 0900 Biokaa Jield, lava11 1 82 171117 47 2030-2100 0klahOllll CitJ, OklahOJII 1 Ground 83 9 hl 47 1217 Bo1 ■t (Between Boise and 1 hr1d1&n) Idaho z, 84 7 Jul 47 l:500•140aeryer's Opomtion - IM!¥I8 £1 Yt•Hitr 57 Bridge Corustruct1on Bot stated Clear and dark. 58 Chiet Pilot- Not atated lfot auted Plying 1er-,1oe 59 Pilot Hone Rot stated 60 Storek:eepel" lot Stated Clear at duak 61 Kot stated lfone Wot stated 62 lot stated Not stated Cloudy 63 Hot stated BOYel"ing and fluttering, 1'1S1ng Scattered aull and deecendtng. olouda, 64 Executive Direct- Hor11onal OnNalt or ot Housing Authority. 65 P1lot lfot stated Not 1tated 66 Lt. Col, QSC Horizonal Pl1.g?\t lfot 1tated Sc1ent1t1c Branch Research Group. 67 Insurance Adjuster None Clear 68 Prospector Banking Cleu 69 Not stated Hot stated Not 1tated 70 Insurance Agent Not stated Clear 71 Capt. AC Reser-,es Not stated Clear 72 A1!S1 0tf1ce1' Not stated Cloud to1'118t1on 1oattered abOYe 10000 tt. 73 lavigator Not stated 5/l.O acattered (Conatellat1on cuaulus vith type ail"cNft) tops at 10000, Y111b111ty 10 a11H. 74 Prospector Standi.nc on edge and banking Mot 1tated 1n the clouda. 75 Trout Parm Oper. Rode up and dovn oyer the hills Mot stated and hollow ot the canyon tloor. 76 County COlllliaaioner Hot stated Rot stated It NND 927545 --- PAGE 13 --- In.ctdent Ob ■erTer'• Ko, Qo9upgt109 Manemrp J!eather 77 Astronomer Not stated lot stated 78 Lt, USI (P80 Pilot lot 1t1ted lot ■ tated 79 Weather r-,o7tff Rot 1t1ted Clear 80 Lt. Col. USAP Jot ltated Scattered clouds Y111b111t7 10-12 ailea. 81 C1T11 Service A1oendtng slowly bplo,ee 82 P1eld Bngtn,er Bot stated lot stated 83 Pilot Slow roll or barrel S projec- tiona on upper sur- face which llight han been thick fine or nob1. Tne,e croaaed each other at intervals, 1ug­ ge1ting either ro­ tation or oaci lla• tion ot alow type 5 lot 1tated Round .Not 1tated .llom 6 1'h1 ti ah-brown Diac Jllot atated Jllom 7 J.lumima Di1e Mot determined lone 8 White Dile Out ol light be­ !tone fore det&iled ob­ Hrfttion •d• Sa 1'hite Diec Out of 11 ght be­ Mone ror• detailed ob­ aen-at1on made 9 Like s hiny ohro­ Di,o Mot 1tated !lot stated aium hub cap 10 .bot 1tated Thin a.nd a.ooth Not stated Jot etated on bottoa, rough appea.rinc on top NND 927545 --- PAGE 15 --- II~· ,DENTIAL Inoident llo. Color Shape She Sound 11 ffbi t e Saucer Jlot stated ~t stated 12 mot atated Like tlock ot •ot stated Low hmmdng geese aound 13 Resembled •tallic llot 1tated lot 1tated l ot atated lt Lin a new di•• Like a nn dime Like .. run, di• lot etated 15 Sil•er lilot atated lot atated llot stated 16 Not stated Not stated lfot auted 17 ltirror bri t ht Approximately Diameter equal to lot atated circular. no tail di atan ce between outboard enginea of DC 4: 18 Jellow llot s t ated Not stated 19 Reflected the 1un Like ci ga.ra - Jlot atated Mom brilliantly 11uch longer than wide 20 Silnr Round About 12 inches in Mone diameter 21 Dirty 1'hite Betwe.n circle 175-2 50 t't. dia:aeter Like electric nnd on.l - in­ 12 ft. t hiok motor or dy­ ••rt•d aa.uc er nmo 22 Shiny d l nry Slim body Quite large Bri ght and sil•ery Ral t-circle Not atated Not stat ed 24 Gli&tened in av.n Too far away to Too far away to lone dotenune ahe.pe dete nain. ahape 25 25 Luminous Plying saucer - lot atated lot atated DO tai l 26 lot 1tated lilot etated Jiot sta'ted lot atated 27 Silvery Citoular in shape Same apan •• C-54 Wot stated ' like a wagon whee l at 10. 000 rt. 28 Not etated ·eomet-11ke Not stated 29 !lot stated Almo1t round lot stated lot stated 50 White (.light) dot stated lot atated !lone NND 927545 --- PAGE 16 --- vbV~r IDENTIAL lnoident No. Color Sha.pc Size Sound 30& Amber Round or oval C-47 airplane Jliono !Ob Bright white to amber Cone-shaped. blunt Rnonnou• on top and taper­ ing orr toward bottom ' 30c White lligbt) RoWlld Comparable 'to run- Bone way light 31 White Not stated lot stated ltone 52 Amber Mot stated tiot stated !lone 33 Sun flashes on metal Roughly circular At the distance and lone or metallic altitude the object appeared ~o be the size of a11Ter dollar ffll.1 te or luminous. Round teudi og to Unknown - altitude Iona ·rurnod to be more be conical a.na distance too red aa the aun aet great ~ot auted Cone. topped with Jot stated lone red :53e Si lver with shadow Raindrop Unlcnown - believed lJnJcnoa to be lar~ 53d 1'h1. te Round at time• - Uneert&in because cone ~haped of distance 53e lfhi. te Round l/4: she full moon lone 33.f l(atallio Bot stated Tremendous SSg "lfot stated Cone 100 ft. high. !lone 43 .rt. acrose Redish tinge Round Large gre.pef'rui t Ion• 35 Fire oolor Ball liot stated llot atatecl 36 )lot stated Bot stated Mot at&.ted Bot stated Reddish with blue lot stated S ft. from point of lone background.. Black view with white baokground 38 SilTer Ball .Not ate.ted Mot stated NND 927545 --- PAGE 17 --- GONfHltJ'TiAL Incident lo, 001or Shape ~ Soupd 39 Phosphoru1 Ba-shaped diaoa lot 1tated lot atate4 ~o Gray El11pt1cal 20-,0 tt. Ho11e like Jet airoratt prior to 1ts appell" - ~ .. No audible sound beai-d 11h11e object va1 1n Yiev. "1 Aluaim"- Round 3 tt. diameter lot atate4 ~2 OH.yilh Balloon 10 tt diaeter lot 1tate4 1'-3 Dirty 1'lite Between a o1.role IJ1d 12 tt thiolc and llectJ"ie Jlotor an oval (ln-.erted 175-250 tt diameter ordynaao sa~er) 44 lfot atat.d Jlyina Saueers Wot 1tated none (not actually des- oribed as being this shape) lJ-5 Hot stated Rot stated Hot stated Bot stated 46 Silvery vh1te Round Small lot stated 47 No detin1te Bo detim.te shape C -51'. airplane lot deterained oolor top due to the noise ai(!e l"etleot- ot airplane. ed 11ght. lf.8 Red PllUli.ng Red cone Wot stated Rot stated IJ.8a Bright light CirculU'-like a •tU' Ve17 lai-ge cOlll)U'ed Hone ohangi.ne to 1n tbe ak7 only luga. to an aeroplane 11,;bt. red then to White OI" J"•llow 48b Red - ldltn Cone Hot detel'llintd Jot 1tated descending Red men IIO"fin8 lot atated Kot 1tated lot ■tated then grean and black to red. 48d Yellow or tlame Rot 1tated lot stated lot 1tated colored. 49 Not atated Pencil shaped ob3eot !lot ■ tated lot stated t --- PAGE 18 --- cot~FIDENTIAL Incident 10. color Shape Si•e sound 50 Stated aa Referred to aa aauoer Kot stated Jfot atated queer 11.&ht. but not stated as being ot thie detinite shape. 51 11lver Bomd Not stated •ot •tated 52 llhite. ah1Dy Circular like a ball 15-25 tt Diameter !lot atated en the bott011 but not completely round. 521 ■ilk mite Bot atated •ot stated lone 53 Whit. C1roular 36 inches diameter Rot stated 54 Rot atated Not etated Rot eta,ed Not stated 55 RecUab lot stated Bot atated None 56 Dia glow ot Round 2 :tt. d1aaeter Hone light 57 lfot stated Kot atated 58 Blaok Saucer (not det1n1tel7 Larger than C~4 Not stated 1tated •• being tbia airplane shape) 59 Incandescent Hot stated Not atated Hot stated 11Cht without appreciable blue and no redd1eh tinae. 60 Plame oolor Diec shaped (the 11'ter Barrel Bead, dinner Wot stated glow •de 1t look like plate am the aise a oone) ot a plane tl71,ng hi&h. 61 White ancS Bot stated Sue ot Pigeons lfot 1tated 111Ullinated 62 YelloV1ah Bot stated 811811 Mot stated vhite Gleuaed and D1so (not actuall7 , rt. a1aaeter and lot stated Shialered stated aa being ot ot no great th1ok• this shape) neaa. 64 Color 111111ar Kot stated lot stated Hot stated to eiectr1c 11.&ht. 65 lot ltated Bot stated 15 1nohea diaaeter lot stated 66 Bright onnge lot stated lot atated Hot stated 67 Jllutal col01" top 1urtaoe al1ghtly IJ.-6 tt 1n le~h ll'ot stated h1ghl7 po111h- ournd-larger 1n front 4 ed chi-Ollium. than 1n the rear . NND 927545 :~e :O-l 1nchea liOMflDENTIAL --- PAGE 19 --- flDENllAL e Incident Col OJ' • I Shape UU. sounc1 68 Hot stated D1eo - appeare~ to have 30 tt d1aaeter lone a tail. 69 White lot 1tated Not stated Bussing sound. 70 Not stated Giant til'e cracker Kot stated Bu11DI aound not aa loud aa a rocket Ship. 71 Rot 1t1ted Hot 1t1ted lot atated Not stated 72 Silver Sphere( nt not like 2·3 tt diameter Rot 1tated 1auoer or diac. Deep Gold 1111pt1oal 15 tt long 2·3 tt lot atated 1n length. 74 Bot stated Tapered lbarpely to a ,o tt. diaaettr Hone point in the tront end. 75 Slq blue Oblong like a broad rill 20 tt. lona am Kade a hat with a low crown. 10 t,. thiolr. av1shiq sound. 76 Not stated Jot 1tated Hot stated Lite the eoho ot • aotor. 77 Light colored Only oonerete evidence 50•100 tt lfide. Loud roar or tora appeared on the lett tangent ot the group. 78 Light gray e1rou1ar 8 tt. diueter Bot ■ tated 79 S1lftl' Bot atated Lu•er than a Not atated Pibal balloon When obaened through a theodolite. 80 Retleoted vh1te "Blob 11 SMll ail"plane Hone light. 81 S11Yer Large Balloon With silver Large lot etated d11c below it, no attaebing ' cables vere noticed. 82 Proa t7 ltbi te Round and tlat Equal to b\11.k ot A 1l1gbt 6 eaob, B-29 air· mahing. planes td th dia .. •t•r to tluomeas ratio ot 10-1. 83 Black Round 'tVtnt,-.f'ive cent lot atated piece. --- PAGE 20 --- , .DENTIAL e Incident 110, color Ship, 84 Sb1Jm7 Road lot ltated lore~ le11 SbJ-111. 85 Bot 1tated Reseabled the D5U•l. Jot 1tated lot 1tated 86 Not 1tated lot atate(! IOt ltated lot stated 87 Jot S1t&ted Bot stated lot ata.ted lot atated 88 lot stated 1lying di ec (not ao­ )lot 1t1.ted lot atated tual ly deaoribed aa being ot thi• aha.pe) Ro\lDd di,o ahaped object 50-60 rt. diameter bot at&ted Refleote4 Unitonn with no protu­ Hot atatad Bot 1tt.t1d light berano•• euoh •• wing• of an airplane Light lot atated Not stated looe 92 Silver lot ,tated S-11 lloli ata.ted Bluish center Appeared to be a di10 Reaembled ~ shooting Not etated ·. rl th rod on at~r; however. ob- its edgH aervera not oertain !ot atatad lot 1tated Not stated Not ,tated 94 Not stated Kot stated Bot stated 95 Not stated Not st:i.ted Hot etated Not stated Not atated 96 91 Flaah of Kot atat•• Hot stated Hot atated light 98 Bright light Ahaoat round or perhaps 2ti-30 miles diametor lot etated oval or aauoer-ahaped Brightly ehining object lot atated Bot atated 99 Shining with long td 1 Wot ,tated lot atated !lot stated 100 NND 927545 --- PAGE 21 --- -COt~f\DENTlAL:- Incident Exhaust - e Speed lffect on Cloud• No. Trail Heading Altitude Ft. l t:one 320° 1000-sooo rt. ~00 mph lot at&ted la. lb Not stated liorthwest 7500-8000 ft. ~50-400 mph Hot stated le ld f.ot stated northwest 7000-8000 f't. 300-400 mph tlot atatod stated tiorthwest 6000 rt. 300-400 mph ~ot stated le tlot From very near Not ste.tod llot atated 2 tot stated Not at&ted the ground to vory high frost to east 10000- 12000 rt. 200- 225 mph )lo-r; stated 3 Not ata.ted Not stated North of due Under 20000 ft . Slower than Hot stated 4 east lllAXimUDl speed or P- 80 Bot stated Two flying Bo'\ stated.d Great speed lot atated 5 aoutb - S flying ea,t llorthweater ly Undetermined Terrifie lot stat.d 6 Not stated Southweat 50000 fto Terrific - lot stat.cl 7 None faster than any object ever seen by him South 40000 tt . Terrific lot atated 8 Rone- Jlone South 40000 rt. ?errifio Not ,tated 8a S01..-th High over Terrific lot stated 9 Not atated Globe Mille Northwest llot stated Cruised for Not atated 10 !Jone 46 min. at oonventional airline apeed (180 mph) then rapidly dis- appeared llot stated .ttoi; a ta. ted 11 Not stated OTer north end lot stated ot Lake 1'o.sh- ington CG."f,DENTIAL NND 927545 --- PAGE 22 --- F1DENTIAl Incident Bo. E:xhauat Trail • Bee.ding .lltitude Ft. Spoed Effect on Cloud.a 12 Wot atated Hot stated Not atated lot • ~ d Hot at&t.h lot stated 65 Low Required ,-4 lot 1tattd 66 Lone atl'a - lorth to South tsht '4\itt 1econd1 to 1treak 11.ll- tnffl 70• ilar to th• an. 1treak left by• traoer bullet. White bail lot 1tattd 500-1000 Tnr1tlo lot 1tated 67 of l■Okt. Wot 1tated Southea1terl1 6000 lot 1tated lot 1tattd 68 Thin 1treaJc South lot 1tateO Vff"f t11t. lot stated 69 of gl"e7ill\ color. Bitber 1aokt 1B to SV 1000-,000 a.oo,oo 1ot 1tated 70 or conden- eat1on laat- SAI 2 1eoonda. 7ooteoo lot stated 71 Jilt)' hav• Southeaat then wot atated been IIIOkt t\ll"Jled and vnt or npor net. t r • 1nttnae NND 927545 ■i,eed WI aiaoet wit•. --- PAGE 27 --- r~eE·~flAl: Incident lo. llxhauat ffiil - Bgd1ng ~hr iiUuii i i 41t1t1»4e Pt, • Sp••4 Vtftt op Qlouf• 72 Iona South Below 10000 'flteaendou Jot 1tated 1, lone Ba1terl7 7000 175 IIPh Rot 1tated approxillatel1 110• -,netio. lot stated •ot 1tated Jlot ■ tated Oreata thd&ft7• thm, n•r Witneaaed. 75 lone Baat to wet 75 lot ,tated loi atated 76 lot stated Bot 1tated 4000-6000 lot atated Jot stated 77 lot stated Jfortihwat(Trut) •ot stated 600-1200 lot •ta'-4 78 lot stated 8va1&ht down. Deorna1Jlg tr• Inaono~nblt lot stated approi111atelJ 25000. 79 Jot atated Batt to lfe1t LIii t.ban 15000 Jot atated Kot 1tated 80 Jone southeast Lesa than 500 CCIIIPUttd at lot atawd ·1:550 IIPh, hOWffJI IP• pelNd to aOTe "1th tbt speed ot • Jet 11.Jlcntt. 81 lot stated • ortlnreat 6000 lot stated Bot stated 82 lone ,5t• 10000-18000 Tbree t1M1 lot 1tated that ot a Jet atrontt. 8:5 lot 1tated lot atated 11000 lot stated lot atated 84 lot atate4 lortbeaat 7500 lot atahd lot 1tated 85 Bot atated Borth 8500 35011Ph lot atated 86 Jfot etated IOJ1thard lot stated lot 1tated Rot atated 87 lot stated Not etated trom 6000 lot stated lot atated 88 lot stated lot 1tated 200 yards 110vhig ra,- liot stated ?idly 89 llot etated Eaet 11000 210 mph JIJot stated NND 927545 CONFIDENTIAL --- PAGE 28 --- 11JcnTIAl Incident Bxh&uat lo. Trail Beading lltitude Ft. Speed Ureot on Cloud• 90 One w1tneH lor'therly 8000-10000 lot atated lot atated thought be eaw Tapor traile 91 lot stated Diaappear ed Great height High rate lot atated in the aoutb- ot apeed weat Jlot stated W.at Abon 1000 Oreat a pffd lot • tated Dropped troa Iot atated Ver, high lot atatecl sight on north Telooity aide of •t. Tom near Holyoke. MaH. Green and Deaoending Ter- Prom lSOOO 'fery high liot atated blue tleaea tioally rate ot apeed 95 Se..-eral color• Saatwa.rd Very high Jlot atated ot r1..... - rate or red and green apeed predomin ating 96 lot stated Bot stated 1200-1500 lot atated Hot atatecl 97 Wot stated 1'ot atated Mot stated !lot etated Mot atated 98 lot stated Jlot atated lot at&ted lot a tated lot stated 99 Mot atated lreat to eaat tilot stated lot stated llot atated 100 Grey streaks Borth to aouth lot atated .llot stated lot atated were left in eky . NND 927545 --- PAGE 29 --- lfOtE: Inc1dent f 18 It has now been d•tini t•ly determined that both tho photograph and story were t. hou:, perpetrated tor publioity e.nd aooey. Incident #8• The peraon malting t he report on thil 1nc1deat was detsrainod to be &n excitable person, ••r/ talkt.tive, and poaseaaing a.n ex­ a ggerated.. iugination and 1nol1ned to iJlpreaa people with his continuous uhatter. NND 927545 --- PAGE 30 --- CONFIDENTIAL REPORTED DIRECTIOIS OF PLIGHT D 5 I 2Z 34 Circling 16 s Straight down 5 • 1'he re an undetermined number ot ob­ Directi on Indefinite 64 jecta ware reported the minimum number Direction lot Stated 61 of object& are pl ottedo Same object reported by di !'teren t p,ople only shown oncto NND 927545 CONFIDENTIAL --- PAGE 31 --- , NND 927545 --- PAGE 32 --- --- PAGE 33 --- eCONFIDENTIAL • Identit1c&tlon ot Subjeot llatter (a, per ••Pl•) IIOU 11CIT 19 Feb 48 l l. Reterenoe 1a ade to th• £11&1 tann b7 llr. Rhoad•• (In.oident f,40) which ••re tonrarded tor exuination. Tb• tollcnriq data ••r• dtri·Hd. froa a atucly ot the 1peciaen1 a. It ia oonoludecl that th• me• ii of tne pbotogn.phio m.ture, and 1• not due to 1~rteotion1 in th• nul.S.011. or lack o1 deTel opaent in the ■ to­ tion in quHtion. Th• im.c• •xhibit1 a "tt.11" indicating th• pn,per t)'~ ot di1to·rtion due to the tne ot 1hutter u1ed, tht apt.cl of the o'bj•ot and tht fixed •peed. of the abutter. Thll trailing ott oontona, to th• g.ntral intor•• tS.oD gi T~ 1n th• report. l>. Th• nport 1tatH th• objeot na •••n a.1- approxiat•ly 2000 t••t at tho t i • ot expoaure. !he obaerHl" allO report, bein& abl• to Ht oltarl1 t. oanow of •nolo1v•. !h• Tiaual aoui ty ot an aTerag• perao!lf'woulcl allow tor thi• peroeptioa, bu't oH•te:l Illy not auoh t'\ll'ther •• 'the 1ubjeot Md low fl nal ooutraat, being cn.y againat a C!'&T •~• It•• ou e1tabl1ah the 41,teoe troe o&aora ~o 1ubjeot, •• Will h&Te quntlty ,fl. !he report 1tate1 tha.t a 820 oaatrt. n.1 u,.ct, in4ioat1ng Hnn.l po111Mlli1••• ti.not tht 620 ia ooa111cle.tur• for the •pe>oli~ a.114 width ot the til.a •• aay h&Ye mptiT•I 2t' X 2t", 2f X ~ a.n4 2-t x 4f'. The aaapl• aubaitte4 ha.cl been out and it wa1 not po11ible to Ht&blilh the 1xaot traat dse. !be 2t x 2f' Iii• waa rul•d out, 1-anrc 2¼ x st" a.nd i¼ x ~ . It 1 t ftre th• ro,...r, them. the tooal leqtii ot the 101 would be ••• an4 uelisg 2000 teet ... the approid.u.te aubj•ot diatanoe and the lagt dH at 1/M•, .. ban an app,onaat• ••se ot '4 t••• a, the cllagonal of the objeot. low 1t wa ohoo ■• the latter n.lue ot a• tor t.,eal length, •• h&Te an approxi• •te T&lue ot' &&• tor th• cliagon&l. Poln-t:1 ot meaauNaent are 1ndioated troa . x to x on lxhibit •••• CONFIDENTIAL NND 927545 --- PAGE 34 --- • " NND 927545 --- PAGE 35 --- • NND 927545 --- PAGE 36 --- THE AEROPLAtlE I FEBRUARY 13, 194& 18S # The Biolo! of the Flying Saf cer- I The Story of Low Aspect Ratio Aircraft By A. R. Weyl, A.F.R.Ae.S. EVERAL MONTHS AGO peo ple o n both side.. of the o ther hand. the U.S. Air Force considered the matter seriQU\ S Atlantic rushed into print wnh claims of having ob~erved queer saucer-shap ed aircraft which new very fast . Some main­ enough to warrant inve..tigation s into the incidenis which had been reported. ceased tained, indeed. tha t they had seen ,quadron\ of , uch mysterious In the meantime. the occurrence of Flying Saucer\ ha.. ob{"ccts; others described vividly how these celestial saucers v.ere to be new\. P resuma bly. the~ have all landed. [A new crop ab e 10 descend vertically. All agreed on the \aucer-hl.e , hapc. wa<; reported in Tur AER0PLANF for J anuary 16 la~t under the Sceptics considered that, for non-aerona utical people ltv1ng heading •• Tuppence Coloured." -Eo.] far from the former playaround s o f V . I. V.2, a nd all the rest Aerooaudc-al Aotlquities and lniquititt of H itler's "civilizator y • practices. flying saucer<; might indeed As a matter of fact. saucer-\hap ed aeropla ne.. are not quite constitute phenomena of threatening aspect, from their experi­ ence of domestic disagreemen ts. Doctors, however. hastened to as new as some people have tried to mal.e out. (Fig. I.) Quite assure the World that saucer-shap ed or lenticular objects could a number of a1rernft have been constructed and nown with well be nothing more than specks in the lenses of the eyes of the wi11gs of the ring or disc type which could well have been mis­ observers- the so-called m11sae 1·0/ames associated with high ta ken for saucers. hat-brims. ~pades, doughnut~. diamonds. blood pressure. Teetotallers blamed the sorry consequence.. o f Greek letter,. pancal.e\, nat fhh. geometrical symbols. d inner imbibing intoxicating liquors for the observation s. On the plates, and other entirely non-aeronau tical commoditie s. Moreover. it is qu ite true. .and not even a minor secret, that, at present. aeronautica l engineers are paying increased a ttention to s uch queer wing shapes: disc wings. for instance. permit ceriain disadvantag es of conventiona l wing\ to be overcome. It 1s even thought that such shares have been neglected too long 1 he blame for rheir neglect can be ascribed to the doctrine o f the induced drng. When the Lanche..ter-Pranc.ltJ aerofoil theory became recoi,1nized nearly 30 }ears ago, and \\hen the !>a1lplane movement proved that slender wings were a necessity fo r soaring. designe r, began striving a fter .. good .. aspect ratios. The theory blinded their eye~ agains, the poss1bili11es of other than convenriona l wings. T hi~. hO\\Cver. was not the fault C"f the theory.,\\ Prandtl soon sho\\ ed its restrictions. We have now come 10 reconsider the matter of wing shape in an objective way. as it is quite possible that aircraft design is approaching a cul-de-sac ~o long as it retains it~ bias in - - 6 - - - -~ ==~ Apttro.l 1 L-- .I_ _°' _ _ __ _,_ ' _'°' _1_ _ ____,, - r . : - - i , (b I c 6) OCl5S • stCTIO!'I \ ,pa" C chor4 \ )(•-,lod a,u Fig. 1.-" Turbine flying machine" (project) of the Munich engineer Gustave Koch, 189311894. Tailless monoplane of low aspect ratio. propelled by a ducted fan. A SO h.p. t SquHC' ...~ , steim engine wu deemed sufficient for th is flying motor car. The design of the duct shows intelligent anticipation. Fig. 2 (Right).- Definitlon of the aspect ratio of an aerofoil. L ...._______. I- b , __j AR • 0-1 l t t The arrows signify the direction of the air flow against the wing. The terms pteroid (feather-like) and apterold have ttt been introduced by F. W . Lanchester. NND 927545 --- PAGE 37 --- \ I THE AEROPLANE 186 FEBRUARY 13, 1948 C..HlUr of the "well-tried " convention, .. normal " wings. For the c reasons. a study of. the hi\lory of the u'IC of low asp,.-ct. rat,o) m wing de:.11n will be of interest. Sp1ruually, the fathers of uch acronauucal exhibits were Ens!"hmen. 1 hey were people of good reputation ttnd by no _me.ins suspect o( aerodynamic perversion. F. W. Lanchcstcr was undoubtedlf the first acrodynamici ,t to g,~e thought to aeroplane winis ot circular or squ.irc ,hapc. lo ht) bool.. publl\hcd m 1907, he referred c'tperiment th.it we lent aspect ratio. hope to repeat u ,U a later date on a more ..c:1entific levcl.- Eo.) In common with circular wing,. annular wings have the fhe conven11onal aeroplJne " constituted of two ba\ic aero­ remarl..able property that the lift force ,teadily increases with frnh: a "ing (,, h1ch ,uppl1e~ the lift) and ri tail (,, hich balances incidence up to fairly high values without a stall. For all and ~tabilize~ the wing). We I.now that \Uch a n arrangement I.no" n arrangements the maximum lift seem, 10 occur at o.f the 111.0 aerofoil compnnenh i, by no mean, the only pos­ incidences exceeding 30 degree,. A, ,uch h igh angle~ of \tblc one. The balancing .ind st11b1lmng aerofoil (tailplane) incidence are not likely 10 be reached an flight unintentionall y. need not to be aft of the lifting wing a, a tail. It can be It 1s obv1ou, "hy annular wings have become renowned for arranged anywhere 1n relation to the wing. e.g .. above It, belo11. their good-natured flying charac1eri,1il:,. it. o r in front of it. Another property of annular wings (first establi,hed by If the balancing aerofoil i, in front o f the main win~. the aero­ Tilghman Richard,) i, that the centre of pre,sure of ,uch wing plane i~ of the tail-first type. and if it i, attached to the ,y,tcm, i, nearly stationary in flight , or that a travel o f the centre of pre,wre can be obtained which i, po,itively stable unul incidences o f the order of 18 degree are reached. In fact. no case of longitudmal in,tabihty ha, ever been reponcd w11h an annular wing. although the centre of gravity has often been located d:ingerou,ly far back. The fi~t annular-wing aeroplane dates bacl.. 10 1908. It h,1d little succe\\. Two type, 11.ere con~tructed m ,ucces\ion tu the de,1gns of a capable German aeronautical engineer, Fritz Huth. who "as by profe\\1on a teacher at a technical ,;chool ( f-tg,. 4 and 61. The ,econd type. which had a less elaborate a1r,crcw drive. flew in May. 1910: it wa,. however. ,o devoid of performance. in spite of a SO b.h.p. engine. that it was soon ,1f1erv.ards d1..carded as a hopeless proposition. Britain'~ Fir..1 Doughnut The Bri11,h concepuon of the idea has been for more ,ucccs,ful. A, it i, cun,1i1u1ed, until now. the best tried reprc,cntativc. it~ hi,1ory may be given somewhat more c,1cn,1vcly. Ihe ori~mal idea for an annular-wing aeroplane came from (,. A K itchen. m about 1910; he con,tructed a b1pl.1ne with Fig. S. Kitchen's doughnut of 1911 . rini:-,haped wmg,, but made no progrcs, "ith it. The stable NND 927545 --- PAGE 38 --- FEBRUARY 13, 1948 - flight of K itchen's models. however. convinced Cedric Lee that an aeroplane of such de~ign would be a succes,. 11nd late in 1910 he acquired the patents. At the same time, G. Tilghman Richards, who was a qualifii:d aeron:iutical engineer, became , ~uffic1ently interested in the mailer to give up a budding engineering bureau in order to join Cedric Lee and 10 devote 187 ·JUI· tl?,!i m THE AEROPLANE hib energy 10 tbe idea of a ·• safety " aeroplane. Tilghman Richards began with systemat ic experiment, on __.._ models and on large gJiders. Later, careful wind-tunnel test~ -:'x: (including the o bservation of the pressure distribution) were - -'- made by him in a :!-ft. tunnel he had constructed at East London College and al~o in tunnels-of tile National Physical Laboratory. The preparation of the design was, therefore, uncommonly ~-ardul for this early period of 1911 - 1914. In o rder to ap(>reciate the intention~ for the development, the following quota11on from a paper read by Tilghman Richards in about 1912 is illuminating: - ... . . 1 he ve ry fnct of high lift occurring at small angles rreans the provision of large area for l•nding speed resulting in an inefficient altitude of the plane at high speed: and the inherent instability of curved aerofoils means a continual dependence on extraneou, controls carried at some distance f_rom the wing by heavy and redundant Structure. . . . High lift at small angles il> u~eles~. likewise h igh lift/ drag ratio at Fig. 6.-Huth annular biplane of 1909. ,mall an,les, and what is required is the reversal of the normal type of hft c urve i:iving little lift •lit small angles with low value and Gordon Bell. Finally it came to i;ricf when flown by of the lift/ drag ratio for landini. . . ." Seen from our pre.sent state of knowledge and development, Cedric Lee himself without previous training. After a good fliaht he managed to put it into a river. a nd facing the burning problems of personal aircraft for the Another incident happened with a subsequent annular man in the street. it wo uld seem that this opinion is a very i;o~ argument for further experimentation along the lines monoplane: the elevator jammed anct broke in flight. The indicated. aeroplane merely pancaked to the ground, again preserving _The. experience with _powered aeroplanes was at first beset the health of i~ pilot, E. C. Gordon England. with disappointment~. Famine P_oint, Heysham, was apparently These types in their final form had lateral control effected no t a spot from which aeronauucal experimenters could derive by differential deflection of the elevators. It was realized that any comfort. this elevon control was not very effective for lateral manceuvres. The original Kitchen biplane with a 50 b.h.p. rotary engine yet the lateral stability of the wing proved so great that the was wrecked by a gale, during I 9 I I. before flight tests could provision of ailerons seemed superfluo us. The loneitudinal b~ m~de. After recort~truction some flight~ were performed stability was always satisfactory, once the centre of gravity was wtth 11 at Sho!eham ; for the pilot, but. unlucky for the The third British monoplane of this type also had an 80 b.h.p. precious craft. After havmg flown a large circuit on the first rotary engine. but this time it was located aft and. further, drove attempt. the pilot noticed, when coming in to land that the the airscrew by means of an extension shaft. Unlike its pre­ aeroplane was exceedingly tail-heavy and getting out ~f control d~cssors, ~~ dihedral was provided. and because of this the the elevator. bei!Jg insufficient. At about 150 ft. above th~ flying qualities were found to have been greatly improved. ground the inevttable stall took place: but the pilot managed From early in 1914 until the outbreak of the 1914-18 War ~~mehow to drop his mount upside down on to telegraph this unco nventional aeroplane was frequently flown (mostly wire~ and escaped without personal injury. by Gordon Bell): it was demonstrated before Winston Wtth the reconstructed and improved monoplane many Churchill in the hope of securing orders from the Admiralty. s\iccessful flights were made by G o rdon England, N. S. Percival Altogether, 11,000 miles were flown in about 128 hours, a nd eve~ people not previously trained as pilots were able to fly 11. In Ma y, 1914. two such aeroplanes were being designed for parlicipation in the Gordon-Bennett Race of 1915. When the 1914-19 18 War terminated the work. it had clearly grown far beyond the stage of an untried project and could have well been termed a successful experiment with every prospect of becoming a practical proposition. In l?l~-10 Tilghman Richards succeeded in persuading the Air Mm1stry 10 place a n order for a further experiRlental aeroplane. But a week after communica1ing this decision Major-General Bagnall-Wild, the promoter of the idea, retired, and red tape killed an intelligent intention. It is only fair to record that aeronautical progress has suffered fr~m the failure to have this develop'ment continued. As Tilghman Richards stated many years ago:- .. There i~ no!hing myMerious about th~ annular plane. It affords high ltft at large angles, ha~ no >urble point and has ~ good lift/ drag . rati_o for wings with a body. ' The !Tiachm~ was very fast in p,ght. for its day, and extremely slow m lan~mg: and there bei!)g three dislinct regions of lift, one a ptero1d and two pterygo1d on each half-wing. the movement of the centre of pressure was a resultant of three distinct regional movements; ,tnd with slight modifications could be made 10 move in any desired manner witho ut affecting the general efficiency of 1he plane." As _mentio ned. th«: c!rcular shape for the wing is not in itself ~ dec1s1ve cha".\c1enst1c. ?reviously. in 1908, A. H. Edwards invented the ring-type wing with rhomboidal or triangular shape_ (Brit. Pat. Spec. No. 4519 of February, 1908). An experimental aeroplane of this type, "The Rhomboidal,'' was constructed and tested at Brooklands. It wa~ not s uccessful. Fig 7.-Cedric Lee Monoplane No. 1 of TIighman Richards, 1912. (To ~ conlit1u~d.) NND 927545 --- PAGE 39 --- .. ,. .. MARCH S, 1948 -­ 279 - THE AEROPLANE The Biology of the Flying Saucer- II By A. R. Weyl, A.F.R.Ae.S. In this series of articles the history of low-aspect-ratio aircraft is recounted and technical aspects of their design discussed. leading up to their use for supersonic flight. (Continued from J>Olt 185, February 13 /rut.) qualified aeronautical engineer (Fig. 10). The Willoughb} THE SECR ET-CIRCLE "CONSPIRACY;• mentioned pre­ viously in connection with circu)ar-aerofoil aeroplanes. did not lack congenially inventive spirits. Early in 1913 an engineer Delta Co. of London had taken up the development of th,., idea in 1931 and sufficient means were available to make rather extensive tests. in D ijon. M. Bou rgoin. made experiments with an annular­ The principle is best described as a tandem monoplane with wing aeroplane. The tests were unsatisfactory. One feature two aerofoil-shaped parts connecting the leading wing with the trailing wing near the tips. The "side wings" had aerofoil of this design was the provision made for varying the wing shape not only in their longit ud inal cross-section (i.e., in the incidence in flight. direction of flight). but also laterally. This was considered a More recently, a similar idea was suggested by N. H. Warren characteristic feature and subject to patents. It was claimed and Th. R. Young (Fig. 8). In 1937 they secured a p atent tha t the vortex distribu1ion induced by such shape gave an ( Brit. Pat. Spec. No. 508,022 of December, 1937) for a non­ unusually h igh aerodynamic efficiency in spite of the small span stallable monoplane of rhomboidal shape (i.e., leading wing of the aeroplane. In addition. it was pointed out that the swept back and trailing wing swept forwards with the wing lips maximum lift was shifted to very high incidences. Moreover. merged together). This was provided with a conventional tai l the "side wings" should reduce the drag of engine nacelle, at 1he stern of a long fuselage and a number o f advantage~ filled underneath them. All this was said to be proved by extensive wind-tunnel experimentation here and abroad. Designs of passenger trans­ po n aircraft reaching weights o f 40,000 lb. were prepared on the basis of model tests made at the National Physical Laboratory a nd elsewhere. T he results must have been so encouraging that a n experimental monoplane with two 125 b.h.p. Menasco e ngines and weighing 2,540 lb. was constructed late in 1938 (Fig. 11). This aeroplane flew indeed and was even publicl~ demonstraled (including one-engine flight) a1 a Garden Party in May, 1939. Shortly afterwards the experimenter was killed in an uneitplained c rash during a flight test. From pressure plots over the "side planes" which have been published, apparently trim changes could be eitpected at various aocidences. These components were thus capable of producing long itudinal inslability a nd it is not improbable that this and poor control efficiency may have contributed to the accident. There was a lso evidence of a stall at normal incidences. although of a very mild character and with little apparent decrease in the lift c~fficient (which. however, would not exclude the presence of fl uctuating lift forces). 11 Fis. 8.-Project by W arren and Young for a liJht twln­ en1lned two-seater of 90 h.p. (1937). The elevator is fitted between fin and fuselage. There Is no tailplane. were claimed. lo 1943 a model for a two-seater fighter with tail turret show~ the separate tail omitt~d; special emphasis was laid oo the triangu lar shape o f each wing and the effect of sweep was relied upon. N othing more bas become_ known since however b ut it is worth noting that the proJect had been'based oa ;ound aerodynamic considerations. lo 1933 the annula r wing of the German sculptor Antes created a mild s~nsation bc<:ause ?f the good performance oC models made to th is coocepuon (Fig. 9). Some.what pecul iar was the aerodynamic ~onceP.tion of the = rhomboidal annular aerop lane of P. Nesbitt W11loughby, a Fig. 10.-frinciple or the W illoughby Delta design. Another suggestion for an annular wing was made by L. Peel, in 1944. This. however. was concerned less with the aerodynamic p roperties of such wing systems than with the arrangement of two engines facing each other with their air­ screws. in order to overcome the torque reacuon. A phenomenon of which aerodynamic experimenters were alwa)ls well aware. but which aircraft designers failed 10 u1ilizc, was that wind-tunnel tests clearly proved good-natured stalling p_roperties of wings having very small aspect ratios. Yet even m the very e_arly days when centres of gravity were far too far back on the old box-kites, the square shape of tailplanes. then unaccountably in vogue, ma y have saved the pilot's bacon more than once by its refusal to stall under eittreme provocation. Later on science came and proved that a tailplane of "good" aspect ratio was more eflkient. It was, but it made the stall worse when the centre of gravity happened to be rather aft. The interesting thing is that aerofoils of circular or square shape were tested in the early days at incidences up to 90 degrees, while o n normal aerofoils tests were restricted to rather Fis, 9.--Model of the "annular wing " ~f Ant es. 1933. small incidences onl y. generally ucluding the range o f stall. NND 927545 --- PAGE 40 --- THE AEROPLANE 280 e MARCH S, 1948 argument against disc wings. The best aerofoil sections in use prio r 10 about 1925 had a plain camber which implies travel of c > the centre of pressure when the incidence varies; the length of such travel is linked up with the wing chord. Hence the change in trim o r stabiluy is. with such aerofoil sections, greater with large-chord wings. On this consideration of fore-and-aft stability and control, designers bad some justification for thcir decision against experimenting with disc wings. Yet quite useful aerofoil secuons had a lready been used in flight which \ I \ I had practically no travel of the centre of pressure and hence I I I I I I d id not suffer from thi~ disadvantage of the disc wing. \,' I I \,' The whole argument, however, lost its importance imme­ diately M. M. Munk proved that very efficient aerofoil sections could be designed with a completely (or nearly so) stationary centre of pressure. It is. therefore, right to say that from that time all conditions existed for a practical evolution of d isc-wing aeroplanes. F. Handley Page converted an aerofoil, leaving an aspect ratio of 6.25, into six square-aerofoil po rtions by five slots. each parallel to the chord of the wing. By so doing he hoped to have the low drag of a oormal wing combined with the high stalling angle of the d isc-type wmg. Although a very slight improvement was claim~d , the principle was that of eating the cake and having it too: the induced drag is respon­ sible for the stalling properties of the d isc wing and you cannot have the benefits of the high drag without suffering its disad­ Fig. 11.-Willoughby's "Delta 8" experimental vantages. Moreover, in o rder to have the effect of the disc monoplane of 1938. wing, the provision of mere slots is insufficient. Marginal vortices need room to deploy. On the whole, however, the idea proves that at least one Thus, an observant student of laboratory tests could have practical aircraft designer had realized that there was some­ noticed the extraordinary capacity of circular or square shapes thing in wings of abnormally small aspect ratio. 10 give a very gradual, innocent stall, an~ that at v!!rY high There were other. although not quue as well thought out, incidences. Yet, a part from a few broad-minded experimenters, antecedents of the disc-wing aeroplane. In the tint soaring­ no designer drew the conclusion that wmgs of such shapes flight competitio n on the Rhocn ( 1920), Friedrich Richter, a promised safety in flight, t~oug_h it w~s known f~om ..~rly burly naval pilot o f 20 stone or so, performed on a triplane practical experience that fly1Dg 10 the second regime, 1.e., glider with wings having an individual aspect ratio of far kss at the stall, was positively dangerous. than three. H. Hayden secured, in 1922, a patent for a rhom­ It is true that spinn ing- Pa rker's "Spiral D ive "-was boidal wing with an aspect ratio of nearly unity, claiming for attributed. in those days, to high i~cideoces, and that most _of such a shape high lift and good flying qualities. the lightly loaded rectangular wmgs used at that period In 192S he constructed a glider with a win, having an aspect rendered the stall relatively. in nocuo us. Howeve_r, :iccidental ratio of only 2.25. The wing was nearly tnangular in shape, ~tailing was then, as now. the cause of the maJonty of all with its apex leading, and a pronounced wash-out towards the crashes. And the nose dive following inadvertent stalls was well tips (Fig. 12); no lateral controls were fitted. The tailplane known to be o f the most serious consequences. . with the elevator was fitted underneath the trailing edge at the Eiffel, Riabouchinsky, D ines, . Prandtl, etc., began the_1r laboratory experiments on aerofoils of very small aspect rauo and the results were generously published (how closely secret they would be kept to-day!). Eiffe l showed that the ratio of the resultant forces reached maxima for small aspect ratios _an~ that slender wings gave the greatest drag at ~ degrees 10c1- . mcthing like a circular wing, a nd performance estimates were based on the properties of such wings. Yet the question of stalling stability did not a rise, bccau~e of the rotor properties. The real pioneer of the disc wing was a very able American research engineer of the National Advisory Committee for Fig. 12.-Experimental Hayden glider, 1925. Span, 19.7 rt. : Aeronautics (N.A.C.A.), who proved capable of following length, 13·85 rt.; wing area, 173 sq. rt. All-up_ weight, independent lines of development. In about 1930 Charles 310 lb. No lateral control. H. Zimmermann subjected the properties of disc wings to NND 927545 --- PAGE 41 --- MARCH S, 1948 281 e THE AEROPLANf wing , tructures as well as for the pos\lbility of housing every· thing w11hm a wing. Hence 1hc1e a re very real design reasons for the preference of disc wings, quite a pan from the ea~cd accommoda11on of short-span aeroplanes. Some R ernurkable Results Zimmermann establ.shed that the optimum a~pcct rauo "'"~ found bet,..een the values o f 0.75 and 1.5. l he,c value, include both ,quare and ctrcubr wmg ,hapes. For a g1Hn win g sccu on (Clark Y) the latter gave the h1gh~t hft coefficient. 1.85 at 45 degrees incidence, compared "uh a value of t.:!4 at 14 degree, mc1dencc for an aspect ratio o f six. Funhcrmore. an important result "'•'\ evidence that at ~,n a,pect ra110 of unity hquare or elhpllcal .... ,ng,), and :11 an a,pect rauo of 0.9 (" mg "11h faired ups), no tendcnc)' 111 ... - -- / autorotauon could be found. A circular " mg (:1,ix-ct raw, of 1.27) ind c.llcd the po\\1hili1y of ~1urnrntation (1.e., ,rinningl at incidence\ below that of maximum lif1. 1 he 1nm1biht)' of ,pinning before the actual ,tall is reached is. indeed, e,tra· ordinary. All these rcwh, r.:fer to te,t• "ith the ( lar~ , Fig. _14.-A Russian • puabola' glider of 1924. aerofoil section. Less establi,hed "as the contenuon th:11 d1..c wing would 11ive improved la11:ral and longuudmal ,1.1h1htv at low incidence, extensive wind-tunnel investigation and the publbhed reports 1 hi, ..ecm, ,11II 10 be a moot point of the Flyin!l Saucer. \till form the ba,is of prc~ent development. In places. In Fig. 16, Fig. 17. and Fig. 18 some charactcri,tic result, ,,f the re,ults confirm, qual1tat1vel)', the experiments made '.!O year~ before. But, as mentioned earlier, these experiments had been praet1C111ly forgotten. Zimmermann' s target has been the development of a really fool-proof aeroplane for amateur pilots. It is no u<,c hiding 7 the fact that in n.:arly all accidents in which blame is attributed to an .. error of /'udgment" on the part of the p1lo1, th.: aeroplane is :ietual y at fault. The moq common causes arc the consequences of inadvertent ~tailing. Once this 1~ completely remedied, the overwhelming majority of accident will become mere incidents or just fun, and instead of coroners and hospitals. aircr.1ft manufacturer) and repair shop) will I! have the benefit On such very sound lines (which seem to be generally II acknowled$ed , but still far too often ignored), Zimrrcrmann I I directed his main attention to the stall ing problem. :;., He ;>roved that small variations in the aspect ratio made profound 't ...~ differences and that the shape of the wing tips also had a great 0-, influence. At the same time he confirmed that the induced drag of circular or square wings is by no means as proh1b111ve as the ~. simple theory of the " horseshoe " vo rtex line would indicate. He also proved that it was simply the induced drag due to the predominant influence of the marginal vortices which brou~ht about the behaviour at high incidence~: the idea that the •• provision of oblique slots might help in this connection proved, h owever, abortive. An advantaae which Z1mmermann' s research brought to liaht was that disc wings gave less profile drag at small CIA°', IIC,,O,. incidences (high-speed flight). because of the reducti on of the -1....____..._ relative thickness of the aerofoil sections. 1 h is drag reduction .,,. JO' -: has indeed become one of the rr.ain reasons for di.c wings being adopted for aeroplanes capable of flying at ~reeds at Fl&, 16. -N .A.C.A. tests by C. H. Zimmermann which prove which the compressibility of the air needs to be considered . the extraordinuy sull1ng qual1t1es of disc wines, Fo r supersonic flight disc wings seem, at P.rcscnt, to be a necessity. Alternatively, for a given aerofoil thickness ratio, !he height avail_able f At the time .of the Arup development (1934). F. Piana Canova. an Italian, began to embark on a development for a tajlless aeroplane with a low aspect ratio. In May, 1935, he "It• 0 It ti ~ 11f 2 secured patents for a rhomboidal wing, one diagonal of which 10 c!, " z coincided with the direction of flight. 1 he ailerons were to ~ 6 t i; be located at the lateral apices. elevator and rudder at the rear apex. while the airscrew was in front of the leading apex. Another patent related to bi-convex aerofoils with ducts and o· • AA ASP(C f U flO ( •' 1J control valve~ for the pilot, enabling the latter to neutralize the negative oressure on the forward ventral surface when at negative incidences. The latter patent was, apparently, never Fig. 117.-These resulu from Zlmmermann's wind-tunnel submitted to flight experiments. tests on disc; wings (1932) clearly show the character!stits (To ~ confin~d.) of low aspect ratio aerofoils. NND 927545 --- PAGE 43 --- MARCH 19, 1948 , 337 THE AEROPLANE The Biology of the Flying Saucer- III By A. R. Wcyl, A.F.R.Ac.S. Previous articles In this series appeared In " The Aeroplane" for February 13 and Morch 5 WofI of0five-·11h1,UNC:anovo1 "'!Cnl l· L I F-••n S w.:rc made in I unn and at Rnme project\ {de-.cnbcd m the prcvtom tn\1,11- ar1de). It " in1erc,11ng 10 note that 1he Canov.1 d1-.c-wmg lype, d id not mal.e u,e of rellc'Crcws driven by two 100 b.h.p. engines mounted in 1andem a n arr.rngemcnt. the wing system i, not tha1 of a di-.c. It is m the long fuselage. 1 he pilot's cockpit was located at the more akin to primitive kites or. belier, to the paper dart of root of lhe fin, and a single·lrack undercarriage w.is adopted. our school day~ which. a, we may be able to remember wi1h 1 here were. however, far too m.iny untried feature in th" some mental effort, exhibited quite remarkable nying quali1ie, unusual design 10 make ii a ~rious proposi1ion. Nothing and made better use <>four schoolbooh than we ever expt-ctcd. more has been heard of Payen's cffoA~. A rcpresent:11ive of 1his aboriginal 1ype is shown in Fig. 19. l he ll)Odern ph:ll!e of .1he Flying Saucer aeroplane i, It crashed during the first tests (which would not seem very charactcn1ed by two d1,ttncl development~. One is the surprising in view of the; arrangement of engine, and air;crew,). hclicop1er-aeroplane, 1he other is the tranb•\onic or buper,on1c Ano1her Je,s eccentric arrangement was the French Payen aeroplane. Hoth have bccome:-unforiunately--cs<;entially single-seat racer of 1935. This was a daring experimental military dcvcl_opment~; the proJ_!re~~ is ~cnce bhroudcd in the type with a 400 b.h.p. radia l engine. A n improved type, this u~ua I pretcnuou~ \ecrccy Iwhich implies that the potential time more reasonable--a 70 b.h.p. light aeroplane- was enemy knows everything) v. hile the work is gravely hampered constructed in 1936. To a very small. conventionally tapered by elabora1c securi1y precautions. wing, a large triangu lar tail was fitted: the wing alone had The helicopter-aeroplane is not a novel idea. Many }Cars d ihed ral. and the overall aspect ra1io was about 1.76. No ago, for in,iance, Nicola T e~la (famous for his elccirical flights have bc.:n reported of one of these Payen aeroplanes. experiment~ wi1h high-frequency phenomena) bccured a pa1en1 but take-off attempts with the ~econd type seem to have for a taille,~ aeroplane equipped with a large lifting air~rcw sugges1cd that with 1he small span the 1orque reaction of the pcrmi11ing a vertical ascent. air,;crcw ca nnot be adequa1ely dealt with. In 192 1 Claud Dornier ~ecured a pa1ent for a eonvcnlmnal 1/lO C - - ·-~ 1110 C f L lL: .__ ._ GI c• t • Fig. 20.-Llft and drag of wings of different aspect . :~ 120 '--- 100 I ,_ 0 ratio. (Left) W ind- tunnel results obtained Goettingen , in at \ ~j 1920; Goettingen ~~ - 80 n ... 389 aerofoil with 10 per cent. t hick- ~ eo t--t--;illt":!'-~ -+7"lr--+--+..-t---c¥~--+~ 19" ASPECT RATIO ness and square 0 .» ... 1 0 1 SQUARE v, ING wing tips. (Right) ~ " A reduction of the ...a:; ~60 + 2 r esults to an ...~ ~( A 3 aspect ratio of w 0 ._u ,o (t h • ' 0 5 f i v e. by t he Prandtl Aerofoil 1· t Theory of t h e :::; 4l 6 Ind uced d ra g , () 7 s h o w s t hat a ~ w s quar e aerofoil .t (aspect ratio of - - i--c one) does not oQ-"11~t---t--t--:,~o- r-+ ---l- +-~ 20- +--+--I I I- 0 i€ I 10 ID follow the theory. Its induced drag is ORAG C0EfFICIENT 100) 20 less than pre­ I I ~ I DRAG COEFFICIENT < 100) dicted by t he '-- 20 "h orse-s h o e 0. : vortex " assump- I t ion. NND 927545 --- PAGE 44 --- THE AEROPLANE . 338 MARCH 19, 1948 • 100 C t L l ...l' I 100 Cl t 1,10 I Fig. 21 . - LI ft curves of aerofoils ~ 1IO i\ ~ ~ AR 1 --;? :a-: ,_,... / ~ LA>- L,CI" ~ L-/ f -l - ~· -- . o,."' O+ .. C of different aspect ratios. (Left) Wind -tunnel results obtained, ~Vv 100 ~- 100 V in 1920, at Goet• ...- I o"'f3. I tlngcn, w ith ,v AR~ :z Goettlngen 389 ~ eo IA . ~ 80 aero fo i l and ~~ V t ASPIC.T RATIO ~ ~" Lu ~ a 1 Aou,hf square t ips. The V 00 ,.I. ,, ' 0V 00 + ? WING ,__,__ absence of stall at t: 't. . .0. J normal Incidence ::; v v l,o' / t: ::; I+ • • Is In evidence, for '° J ~ -l.,o' 1,,1" fif (r ro t'°I b .. ,· - .o I ~ ,__ aspect ratios up to a value of two. (Right) Reducing ,,. () the values. by the ., . Prandtl theory.to .#J ~ 1 -► (l o· cf --< an aspect ratio of five, shows t hat wings of very 10 ° 10 10 • 10 small aspect rat io I 0 ' I •NGt[ or INCll)[NC( ( O!GRCES i AN(;l[ Of tNCIO(N(( t OIGRH\ I do not follow the 10 ... IO theory in respect of the induced­ ~ Incidence correc• tlon. aeroplane with take·off as helicopter {Brit. Pat. Spec. control organs directly in the slipstream of tht: paddle-like No.161,948). Earlier still (in 1916), the German, F. Bendemann, airscrew rotor... T he twin rudders, too. are in the slipslfeam. a noted fesearcb worker on a1rscrews, conducted a secret Unlike the V-173 type, the XF-SU· l has an all-moving tail development o f an aeroplane with a large tilting airscrew surface and the undercarriage is retractable. capable of rising and descending as a helicopter. The This interesting hybrid has a modern metal structure. Two development of this air observation post was later discon• Pratt and Whilney R-2000-2 engines Qf 1,350 b.h.p. each (at tinued in view ot the Austrian helicopter experiments by 2,700 r.p.m.) are mounted within the wing, entirely buried and Th. v. Karman and Petroczy. cooled by forced draught. Water injection for temporarily From his early experiments with lifting airscrews, boosting the oower is one of the engine features. F. Bendemann found that hoverihg without forward movement A special oroblem was the design of a transmission ~ear could be achieved- when the power loading of the aircraft was which a llows both rotors to be driven from either of the eogmes less than a bout 9 11,.. / b.b-.p. With fighter aeroplanes, such - this is a necessity in case of an engine failure. The four· low power loadings were already then being approached1 and bladed rotors are contra-rotating so that there is no residual operat ional experience bad indeed shown that certain single· torque and are ,eared down to about one-fifth of the engine sealers could. under favourable conditions, be held in attitudes speed, hence their substanlial diameter. The wing loading is a pproaching that of hov.ering (later the Fokker D.Vll biplane, rather high. reaching the order of 40 lb./sq. ft. with a large airscrew, became renowned for this trick 10 air combat on the Western Front). Attempts to revive the project ~ta la ter date failed. and with the suicide of its promoter (who The Real Flying Saucer ? had gone into the Civil Service), all interest lo the development Since this experimental t ype was produced, further progress ceased. • has been made in the development. IL seems that axial-flow Charles W. Zimmermann, mentioned earlier as stimulator of gas turbines have been installed, and it is quite possible that the disc wing, approached the conception of the helicopter a combined oropulsion with thermal jet and airscrew rotor Aeroplane on the basis of his results with low aspect ratio is alt:eadv under test. Wilh this, for slow flight (take-off, wings. He secured basic patents and constructed during climb and landing) the rotors a re driven by the gas turbines, 1934·35, in the cellar of his home, a man-carrying aircraft of while at high speed the rotors are declutched a nd feathered bis design. This had a wing of only 7-ft. span, with two and pure jet propulsion is used. This would, incidentally, airscrews driven by two 25 b.h.p. engines. Due to persistent engine trouble, no flights were made; the Little aircraft showed, however. all the C$SCOtial features of the present types. In 1937 he granted a licence for his patents to the Chance• ( Vo ught Aircraft Division of the Unik:d Aircraft Corporation ~01! 1---1---1------.1---1----1----1 in Strntfort, Connecticut, and /'oined this firm for the further development of his ideas. t is possible that the public conception of the mysterious "Flying Saucers" has origmated from this develo,,ment. - Zimmermann's intention may have been the development o f a safety-first aeroplaoe for the private owner. The U.S. Navy, ; however, took an interest in the possibilities of the helicopter• 0 aeroplane, and the work done at present is purely for military ~ purposes. In 1942 a low-powered piloted scale model type ,. V-173 was constructed. This wooden aircraft made many < flights and proved that the ideas underlying the design were i practical. Q The principle is that, at h igh speed and when cruising, the ::: ...- NACA 14 SEC11C)N:~ aircraft shall fty as an aeroplane, while for slow speed and iSV .., hovering it flies as a helicopter. Hence the airscrews are at 0-00, ._N• '1·1 , 10' the same time rotors and must have a rarher large diameter. ~ 0 With the V-173 the problem of the prone position for the pilot i ~ 0.~L T!HI was studied. and there is reason to believe that the latest types have adopted this feature. A further step towards the realization of a naval gun-spotter ,. ... I - and a fia),ter for use from aircraft carriers bas been the Chance· ~ T{C Vouaht XF5U·l single-seater (1946), for which a speed range ~ from 40 m.p.h. landing speed to over 425 m.p.h. has been ~01 0-ll 0-16 ~IO 0 •1' claimed; in general, it follows the V-173 model. (See p. 185, AU,0r0tL TMICKNESS A.ATIO February 13.) The aspect ratio of the wing is lesa than unity. Strictly Fie. 22.-lncrease of profile drq with section thickness, at speaking, however, it is not a genuine tailless aeroplane because :zero 11ft. The lfnporunce of the tip shape Is obvious. of the attachment of a trimmmg elevator to both sides ot the The data refer to an aspect ratio of flve (From D.V.L. wind- wina. The reason for such excrescences is the need to locate tunnel tesu at low turbulence). NND 927545 --- PAGE 45 --- 0·3 ., ... ~ ARCH 19, 1948 r - - - - - - - -- - - - - - - - - - - - --i~ 339 THE AEROPLANE M. B. Morgan has recently communicated the following values for the limit of stability at the stall from this araph:- <=o, Upper llmic of th• Ansl• of Swetp,back (r•lerred 0 to th• l chord) beyond which Hll••tall can be A,poc, Ratio 11.•qulr•d expected Ocareu 6S 1 S4 2 46 3 38 2S 14 ' 6 8 s •• It is thus advisable to combine sweep-back with low-aspect ratio w!1en s~fc stallin_g is required. . Consaderataon, of high speed lead to a ,imilar combination. since both feature~ tend to delay the shock stall. We have. o-a 04 1·0 as ~ res!lll, the rare ca~ i;,f two quite d ifferent aspects of an enginee~ing_ problem pointing to an identical solution. 1 he incv11able result has been the development of arrow­ Fig. 23.-lncrease of xero lift profile drag with thickness ratio sh<;1ped:. more ?r less triangular, . disc wings, termed " Oelta­ of symmetrical aerofoil sectldn. The saving In profile drag Is Wangs, _for lhgh~ at sp~eds which are trespassing into the one of the advantages of disc wings because of their thinner tr~ns•s?nlC velocity rtg1me. Another advantage of such aero~oll section. (Data from Gerber, Zurich Report No. 6). wings as that when the shock stall occurs. the backward shift of !he centre of pressure is less than with normal wings. The induced drag doe, not count quant itatively at tbeg high speeds explain the extr~ordinary ability of the reported •• Flying Development of such abnormal aeroplane types began i~ Saucers·• to be able to fly very fast and high, and also to hover, 9e:many during the War_. following the progress accomplished ascend _and de_sceod with practically no forward speed. No •~ 1et and r~ket propulsion since 1937, which had shown that ~ther a!rcraft 1s known to do tha t. On the other hand, it is flight . at sonic vcla<:IIY wa, a r,ractical proposition. A few ll!(ODCeavable that whole squadrons of such unconventional experimental delta-wing types had been brought to initial flying atreraft could already be observed at air exercises. It is rare te~t, when the War came to a close. for military developments to progress as quickly as all that. . The German ~evclopmcnt had two d istinct aims, resulting . For operatao~ with gas turbines a speed range from zero 11_1 two separate hn_es of approach. The immediate target neces­ (1.c., hovcrin~ flight) to more than .500 m.p.h. has been claimed satat~d by the Allied bombing raids. was the creation of very for t~e Chance:V~ugh t-Zimmcrman n helicopter-aero plane. fast Jct fighters or fighter-bombers which could surpass in speed Technically. there 1s httlc reason to doubt that such an amazing even the Mc 262. _Secondly, there was the long-term develop­ specect ratio. and a curve based on r,rcpared coal which lined the walls of the doct. This develop­ exten,av~ wind-tunnel te,ts CT11c ~ER0P~~c for Jul y t I. 1947, ment ha~ bee~ perfected by the German Research In1titutc­ p. 47, F111_. 8) proved that there 1, a d astmct relation between for Soarmg Fhaht. a,r,ect ratio and an11le o f sweep-back in this connection. (To ~ continued.) NND 927545