vhich we know nothi.ng. But at this point we enter a field of speculation s o limitless that we can no longe r pursue it at all. I should perhaps also mention the space-satellite, the "artificial moon" as it is sometimes called, which involves the placing of a man-made and perhaps man- occupied object i n space outside the gravitationsJ field of the earth. Many of you may have read the article on this subject in a !.(arch 1952 issue of Collier' s It's a very good article., by the way, and scientifically The idea of the satellite also exerts a powerfUl pul J UJ>On man's imagination. far as our investigation is concerned, ve can find no reason t o believe that such a thing as a man- made satellite exists nov. It may 1n the f'uture, probably will. It may exist nov, in the sense that anything is possible. But ve can find no evidence to this effect. And lacking evidence, without proof , we must disregard the satellite possibilit y in our investigation. To come back at least a little closer to earth, ve vill discuss for a moment some of the other lines of inquiry that have been f ollowed. I will give over now t o Mr. -----' of the Aircraft and Propulsion Section, Technical Analysis Division, ATIC. Mr. i a an aeronautical engineer. He will give you an account of develop- menta in other fields, again in consideration of aJl possibilities, however remote. Let me apeak first about gui ded missiles. The early history of the operationa l use of this weapon is now quite well known. Ita tirat application was during Worl d War II by Germany, with the launching of the 1944 V- 1 or"buzz-bomb" attack on London. These aailes, although strange and fearfUl enough in many ways, did resemble aircraft in basic configuration. Their speed was about three hundred and fifty knots, and their range not mor e than one hundred and forty nautical miles. ATIC - 1 .April 1952 The German V-2, a "ballistic" or bHlJet-like missile as con- trasted to the aircraft-configuration type, was a much larger weapon. Ita range also, however, was short, being about one hundred sixty fiYe nautical miles. In the United States, work on guided mia8iles has been going on with ever-increasing rapidity. The near-operational state of the .MATADOR is probably well known t o you all. This, a vinged, non-ballistic missile, is given a range of five hundred nautical mile. Others of generally similar type, s uch as the SNARK and the NAVAHO, are projected for development betwee n 1954 and 1958 , and "'ill have gr eatly increased ranges up to five thousand five hundred miles. o, in the u.s. program are rocket- powered ballistic missiles ot the same general t ype as the V-2 but with much greater range. I t estimated that with continuing development effort we will have 1960 a multi-stage ballistic missile capable of carrying a mass estruetion warhead five t housand five hundred nautical miles. missil e work is als o goi ng on i n other countries, of course. The Soviets are known to have shown great interest in the German V-1 ATIC - 1 April 1952 and V-2 . It is e stimated that Russian development of the V-2 may have increased its range to about 350 nautical miles. Some increas e in r ange ma y be expected i n V-1 development, but no details are known. And t he Sovi e t s are conceded to have the capability to build mi s siles of the ltATADOR and SNARK types, although there is no siti ve evidence that they a.re doing so. There 1 e, however, con- siderable reason t o believe that they are uorking hard on large r ocket engines for missile application. And it is estimated they may have ready for us e by 1957, a t vo-stage ballistic miss ile Wit h a of t vrenty five hundred miles. They very likely have, today, a rocket engine of 120 metric tons. And nov, no discussion such as this would be enti r ely complete without at least some menti on of the Sanger r ocket drive. Dr.E . Sange r , German, performed hi s experiment s on the rocket drive, or rocket- bomber a s he himself calls it, during the period of 1939 to 1911. His ghly t heoretical and a s yet unrealized proposal for a rocket of extremely long range and pos sessing, oddly enough, both ballistic and aircraft characteristics. It cannot really be considered a guided sile at a.ll, in fact. It has wings, and, moreover, is designed to carry a pilot and to be recoverable, that is, landed, at the end of its mieej.on. An(l yet its range is s o great and its methods of operation ao unusual, that many of its design features come within the ballistic missile category. Dr. Sanger theorized vas a vehicle powered by a rocket engine of some one hundred tons thrust, to be about one hundred teet long, with a wi ngspan of seventy feet, a takeoff weight of roximately one hundred tons, a takeoff speed of around twelve hundred miles per hour, and capable of attaining an altitude of one hundred miles. Its maximum volocity would be about 15,000 miles per hour. Its range is s o great a s to carry it more than half way around the eart h . To expla1n its operation and rather than t~t my interpretation, let me put it in Dr. Sanger' s own words. ays, '',,.the rocket-bomber . climbs at :t"ull motor drive t o height of f ifty t o one hundred fift y kilometers. At the end of ATI C - 1 APril 1952 the climb the rocket motor is turned off and the a i rcraft, because of its kine tic and potential energy, continues on its path in a ort of oscillating gliding flight with steadily decreasing amplitude of oscillati on. Because of its wings the aircraft descending its ballistic curve bounces on the lower layers of the atmosphere and is again kicked upwards, like a flat stone ricocheti ng on a water surface .... t he initially b i g jumps steadil y become smaller and finally go over into a steady gliding flight ... the bombs are released at a predet ermined moment, and the craf t returns t o 1 ts starting place or some other landi ng field in a wide arc .... d~ing gliding fli ght the flight speed decreases from its high initial value t o normal landing speed. It . i s completely independent of weather and tim~ of day at tbe target, and of enemy counteraction, because of . using astronomical navigation in the stratosphere and because of the height and speed of flight." End of quot e . I repeat that no working model of the Sanger rocket-bomber has ever been built so far a s is knovn. But Dr. Sanger is still living, and still a t work --presently for the government of France . ATIC - 1 April 1952 To depart nov from the missile field and discuss aircraft, let ua consider the unconventional aircraft configurations. A great deal of interest has been shown by many designers in low aspect-ratio all-wing configurations as a means of obtaining compact, low-drag aircraft. The elimination of fuselage and tail surfaces in such desi gns decrease the total surface area exposed to the airstream and thus l ower the parasite drag. And the low aspect-ratio normally a ssociated with an all-wing design makes it feasible to design an efficient light-weight structure. work in all wing confi~1rations has been carried on by various designers in the United States since the early 1930's. Of all of the se designs, the most interesting is probably the Zimmerman wing aircraft which was proposed by Chance - Vought in 1939. The aircraf't was to have a span of 23 . 3 feet and was to employ immerman wing (see NA~A report TN No. 539). The aircraft was t o be with two P&W engines of 1 350 H. P . each which were mounted at the wing tips. The take-off distances of this aircraft were very lov, ATIC -1 APril 1952 being 230 teet over a 50 foot obstacle. An experimental model of the aircrat't vas built for the Navy and designated XF5U-1. The rate of limb obtained during flight tests di~ not meet expectations due to the extremely high-induced drag inherent in low aopect ratio wings. The ake-off distance d i d check out t o be very lov. The project vas dropp e d vi t h the advent of high opeed Jet aircraft. pure delta-wing in which many U. S. companies have s.ho.m an interest also appears to h&vo u. high induced drag factor although there its some evidence that this can be ell eviated somewhat by round- ing the wing tips. Convair ls carrying on a.n active project (F-92) t o determine the flying characteristics of a pure de lta-wing aircraft. To date, fairly succesa:f'Ul. results have been obtained and they have been awarded a development contract ro~ a delt a -wing all-weather fighter. always good for a look of interest i n aeronautical c ircles are those of the Horton Brothers and Herr Lippisc h . These two design teams began in the early thirties t o build and fly variou s all-wing glider s i n Germany . APril 1952 The Horton Brothers are now separated, one of them being still in Germany and the other in South America. Lippisch has been in the u. 8 . since 1946. The rather unusual appearance of their designs accounts for much of the interest they arouse. Before I give you a quick run-down of the Borton all-wing aircraft series, permit me to make a tew remarks regarding the general history of wing shapes. It i s a matter of fact that saucer-s~ed airplanes are not quite as new as is sometimes thought. Quite a number of aircraft have been constructed and flown with wings of the ring or disc type which could well have been mistaken for saucers, hat brims, doughnuts, etc. Aeronautical engineers have always toyed with such queer wing shapes. Disc wings, for instance, permit certain disadvantages of conventional wings to be overcome. When the sa1lilane movement proved that slender wings were a necessity for soaring, designers began striving for "good" aspect ratios. A good aspect ratio for gliders would be in the neighborhood ATIC - 1 April 1952 of 10 and higher. The highe r the better. A representative value would be 15 to 20. While the glider enthusiasts were always striving for higher aspect m.tios (and in that category fall the "all-wing" enthusiasts), the circular airfoil designers were dabbling vitb aspect ratios of 1 to 4. This so-called "battle of the aspect ratios" was decided in favor of slender wings (that is, high aspect ratios) in spite of the tact that Prandtl vas eager t o point out that his airfoil theory did not hold water for very small aspect ratios . That,in fact, the induced drag of disc wings was less than his theory suggested . Some early tail-less a irplanes had rather stubby 'nngs and heavily reflected airfoil sections. A 1929 design by the Frenchman, Abrial, showed a n aspect ratio of 2 . 88 with, however, substantial wing tip discs ( which have the effect of increasing the aerodynamic a.apect ratio). Wind tunnel experiments of this model indicated a creditable performance. ATIC - 1 APril 195? UHIDENTD'IED AERIAL P&1feENA 'mE AIR TLCBNICAL IN'I'EI.I.IGC:NCE CENTER Wright-Patterson Air FOree Base Dayton, Ohio Prepared 1 April 1952 The Lippisch delta wing designs arc very similar in their basic aerodynamic aapecta to those of the SF5U. Both the disc and the delta shape make tor high structural rigidity and, consequently , very thin airfoil sections can be employed in these designs. Furthermore, tests have shown that wings vi th high sweep back plus low aspect ratio will give cnfer stalling characteristics. The delta wing plan form, of course, combines both the sweep angle and the lov aspect ratio feature in one package. And now ~re are some illustrations. This is the XF5U-l referred to previously. Thie io a table suunuarizing characteristics ot the Horton Thie is the glider with the two-parabola plan f orm, referred to previ ously . ATIC - 1 April 1952 This is the Horton H-VII I transport. It was deisgned t o carry 60 passengers i n the trans-atlantic run. The facilities at Gottingen limited the wing span t o 158 feet although the original plane called for a larger aircraft. The Horton H-VIII had characteriotics and performance as shown on this slide: Wing span 158 t t Wing area 2500 ft Aspect ratio 1 0 Sweep at leading edge 28 Gross weight 33 Wing l oading 1 3 . 2 lb/ft Power plant 6 BMW engines rated at 6oo bp each loading 9.17 l b lhp Cargo 6o passengers Vmax 175 knots Rat e ot climb 1000 tt/ min rvice ceiling 1 5,000 ft Range 2500 nM we have made a proje ction of the Hort on design which may be of interest. Development or t he Horton H- XVIII. A possible development a s t o performance and characteriotics is shown in this slide. Ass umi ng an a i r craft wit h a span of 153 feet , 'Wing area of 4oOO square feet, and a gross weight ot 200,000 pounds powered with 4 x 10,000 pound thrust engines, the aircraft could have a range of approximately 5000 m.r. Of the German all-wing designs, the u.s . showed t he greatest inte r e st 1n the Lippiach delta-wi ng DM-1 glider. DM- 1 was to be used to t est the flying qual i ties of t he elta-wing pl anform, in preparation for construction of a supersonic t i ghter or t hat pl enform. The DM-1 had a span of 19. 7 feet, a very low a apect ratio of 1 . 81 , and a gross wei ght of approximatel,r 1000 unds. The pilot was housed i n the root of t he l a r ge vertical t i n . Thi s ai r craft was t o have been develope d into a supe r soni c f ighter powered wit h a coal fuel ram-Jet . A comprehensive vind tunnel test program wa run on the D..\f-1 by the l!ACA at Lengle y Field. The original teats vere started upon the recommendations of Theodore Von Karman in ans wer t o a request as to vhethcr or not it would be oafc to flight test the DM-1. Considerable was done by the NACA t o find the maximwn lift coefficient available tor landing and t o determine aink!1~ speed of the glider. triangular wings of aspect ratio ot o.'bout 2, maximum lift coefficients of the order ot 1 . 2 can be obtained. The corresponding angles of attack, however, will be considerably greater t han t hose tor conventional airplanes. Furthermore, since t he lift-drag ratio at high angles of attack is approaching 1, the angles of deGcent without power are likely to be prohibitive and a!rplanea using this type of wing probably will not land sat'ely without power. The Lippiach P-12 delta Ying aircraft was designed as a high erformance interceptor and was to be povered by a liguid fUel ATIC -1 APril 1952 There is a large air intake in the proJecting nose and the pilot is eeated above the combustion chamber forward of the large vertical fin. The undercarriage is composed ot a single central wheel w1 th a skid projecting downward from each wing tip . The only known characteristics are as follovs: Aspect ratio Pover plant liquid tuel ram-jet (rocket l"or initial acceleration) Note: A.t present, no country is known t o have an operational liquid :tuel ram-jet: The leading powers are conducting research and development on a limited scale; no immediate estimates on performance are available.) ATIC - 1 April 1952 Results of tests conducted with the DM-1 glider were to be utilized in the design and construction of the P-13 fighter. P-13 incorporated a delta planform Vith a 6o swept-back leading edge. A ram-jet power plant was proposed but no information is available regarding itc development except that several coal burning types were being considered. slide shows another projection, of the same kind done previously vith the Horton design. It io a projection of the possible of the P-13 design. a development of the P-13 project ~ere actively pursued it wuld probably follow along the original German thinking . Such an aircraft is est imated to have the following characterioties: Wing span 20 ft Wing area 220 s q ft Aspect ratio 1.e Sveep at leading Gross weight 7700 l b ATIC - 1 April 1951 Assuming a typical present day installation of a ( OOO lb. thrust jet engine, the estimated performance would be as follows: Rate of climb at sea level Mach Ilo. l. 0 Endurance 30 min for this aircraft would not be outstanding, pr obably about 300 nautical. miles. Lights on now, please. n-flight refueli ng) as ve have been of long-range possibilities, we miGht mention that we have also given consideration to in-flight refueli ng and the possib ility that our aerial phenomena may be due to conventional aircraft from a foreign source, using the range extension to be gained from recent refueling techniques. It is quite true, of course, that in-flight refueling has greatly ATIC - 1 APril 1952 extended the range of present-day aircraft. This applies to conventional aircraft, however, and since our reports indicating aircraft point to a highly unconventional type, it is felt that in-flight refueling as a possible explanation for the phenomena offers little promlse. Jet Engine Development) To complete our consideration of the field of aircraft development with special ~phaois upon the possibilities of increased range, let us review for a moment the aircr~ft gas turbine. It is a truism to refer to jet engine development as sensational, but I wonder if that tired word "sensational" reaJJy expresses juot how remarkable that development haD been. In some ten years ile have gone fro:n lese than nine hundred pounds thrust to more than ten thousand. Turbojets with dry static see level ratings of about ten thousand pounds thrust are already installed in aircraft and undergoing flight test. And ue have currently in bench teating engines with thrust ratings of up to eighteen thousand pounds. ATIC - 1 APril 1952 American and British developments have been about parallel. Both have gone trom centrifugal flow t o axial tlov compressors, t o performance augmentation by use o~ afterburners and other devices , to improved operations at ever higher altitudes. The Soviets have apparently followed much the same trend. They are now developi~ engines of upwards of ten thousand pounds thrust, and they have at least one, the L~llka, that i s rated at eleven thousand five hundred. And we have every reason to believe that their development program is continuing at a rapid pace . There is no indication, however, of any radically new principleo in Jet propulsion that would account for the reported behavior of some of the unidentified objects as to maneuverability and acceleration ~nll take over again now. Briefing Officer) ATIC - 1 APri l 1952 Thank you, Mr. Kobernuos. (Briefing Officer) As ve have s een from what Mr. Kobernuos baa told us, there is no real evide