USAF Project SIGN file
USAF Air Materiel Command initial report for Project SIGN, dated April 23, 1948. It summarizes early 'Flying Disc' sightings from 1947-1948 and includes a detailed tabulation of 100 incidents, analyzing characteristics like shape, speed, and location.
Extracted images
Images flagged by the classifier as photographs, maps or sketches.
A compass rose diagram showing the reported directions of flight for UFO sightings, with counts for each direction and a summary of non-directional reports.
Photograph of a dark, teardrop-shaped object against a light background.
Photograph showing several dark objects and a fingerprint-like pattern.
Enlarged photograph of a dark, teardrop-shaped object, labeled Exhibit 'A'.
Photograph of a delta-wing or flying-wing aircraft on the ground.
Chance Vought XF5U-1
CROSS-SECTION
Diagram showing different aerofoil shapes and aspect ratios (A.R.).
Fig. 3. A simple experiment in annular aerofoils.
Fig. 4. Principle of the Huth annular-biplane system.
Fig. 5. Kitchen's doughnut of 1911.
Fig. 6. Huth annular biplane of 1909.
Fig. 7.-Cedric Lee Monoplane No. 1 of Tilghman Richards, 1912.
Fig. 8. Project by Warren and Young for a light twin-engined two-seater of 90 h.p. (1937). The elevator is fitted between fin and fuselage. There is no tailplane.
Fig. 10. Principle of the Willoughby Delta design.
Fig. 9. Model of the "annular wing" of Antes, 1933.
Fig. 11. Willoughby's "Delta 8" experimental monoplane of 1938.
Fig. 12. Experimental Hayden glider, 1925. Span, 19.7 ft.; length, 13-85 ft.; wing area, 173 sq. ft. All-up, weight, 310 lb. No lateral control.
Fig. 13. A French project of G. Abrial, 1929.
Fig. 14. A Russian parabola' glider of 1924.
Fig. 15. A parabola' aircraft by B. I. Tscheranowsky.
Fig. 16.-N.A.C.A. tests by C. H. Zimmermann which prove the extraordinary stalling qualities of disc wings.
18. Further results from Zimmermann's tests shown here also indicate the advantages to be gained from disc wings.
Fig. 17. These results from Zimmermann's wind-tunnel tests on disc wings (1932) clearly show the characteristics of low aspect ratio aerofoils.
Fig. 19. An American "Flying Flapjack" with two engines. It crashed while under test (1938).
Chart showing lift coefficient vs drag coefficient for various aspect ratios (AR).
Fig. 20. Lift and drag of wings of different aspect ratio. (Left) Wind-tunnel results obtained at Goettingen, in 1920; Goettingen 389 aerofoil with 10 per cent. thickness and square wing tips. (Right) A reduction of the results to an aspect ratio of five, by the Prandtl Aerofoil Theory of the induced drag, shows that a square aerofoil (aspect ratio of one) does not follow the theory. Its induced drag is less than predicted by the "horse-shoe vortex" assumption.
Chart showing lift coefficient vs angle of incidence for various aspect ratios (AR).
Fig. 21. Lift curves of aerofoils of different aspect ratios. (Left) Wind-tunnel results obtained, in 1920, at Goettingen, with Goettingen 389 aerofoil and square tips. The absence of stall at normal incidence is in evidence, for aspect ratios up to a value of two. (Right) Reducing the values, by the Prandtl theory, to an aspect ratio of five, shows that wings of very small aspect ratio do not follow the theory in respect of the induced-incidence correction.
Fig. 22. Increase of profile drag with section thickness, at zero lift. The importance of the tip shape is obvious. The data refer to an aspect ratio of five (From D.V.L. wind-tunnel tests at low turbulence).
Fig. 23. Increase of zero lift profile drag with thickness ratio of symmetrical aerofoil section. The saving in profile drag is one of the advantages of disc wings because of their thinner aerofoil section. (Data from Gerber, Zurich Report No. 6).
Pages
MCIA HEADQUARTERS AIR MATERIEL COMMAND MCIA/JCB/amb Wright-Patterson Air Force Base Dayton, Ohio SUBJECT: Project "SIGN" TO: Chief of Staff United States Air Force Washington 25, D. C. ATTN: Director of Intelligence 1. This is an initial report on unidentified flying objects…
AMC Subject: Project "SIGN" e. Number of objects per sighting: Objects per sighting 1 2-5 5-10 over 10 Number of sightings 77 21 8 9 f. Exhaust trails were reported 23 times. g. Speed has been estimated throughout the entire range from very slow or hovering to supersonic. 6.…
CONFIDENTIAL
Incident No. Date Hour Location S No. Sighted Observed From 1 8 Jul 47 0930 Muroc Air Field, Muroc, Calif. 2 Ground la 8 Jul 47 0930 Muroc, Air Field, Muroc, Calif. 2 Ground 1b 8 Jul 47 0930 Muroc Air Field, Muroc, Calif. 2 Ground 1c 8 Jul 47 0945 Muroc Air Field, Muroc, Calif. 2…
CONFIDENTIAL
Incident No. Date Hour Location No. Sighted Observed From 21 29 Jun 47 1645 Des Moines, Iowa 18 not stated 22 21 Jun 47 about noon Spokane, Washington several Ground 23 30 Jun 47 1745 Boise, Idaho 1 Ground 24 12 Jun 47 1815 Weiser, Idaho 2 Ground 25. 4 Jul 47 2345Z West Trenton,…
CONFIDENTIAL
INCIDENT No. Date Hour Location No. Sighted Observed From 36 Not Stated Not Stated Boise, Idaho 1 Ground 37 12 Oct 47 12-00 Cave Creek, Arizona 1 Ground 38 10 Jun 47 Not Stated Budapest, Hungary 1 Ground 39 9 Jul 47 2330 Grand Falls, Newfoundland 5 Ground 40 7 Jul 47 16-00 Phoeni…
CONFIDENTIAL
Incident No. Date Hour Location No. Sighted Observed From 56 6 Jul 47 2045 Birmingham, Alabama 7-10 Ground 57 20 Jul 47 0015Z Aboard the Burgeo (at Sea one hr. from Sydney, Australia) 1 Boat 58 4 Aug 47 Evening Bethel, Alaska 1 Air 59 14 Sept 47 0558CCT Necker Island 1 Air 60 10…
CONFIDENTIAL
Incident No. Date Hour Location No. Observed Sighted From 80 7 Jul 47 2230-2300EDT Arlington, Virginia 1 Ground 81 7 Jul 47 09-00 Hickam Field, Hawaii 1 Ground 82 17 May 47 2030-2100 Oklahoma City, Oklahoma 1 Ground 83 9 Jul 47 1217 Boise (Between Boise and Meridian) Idaho 1 Air…
CONFIDENTIAL
Incident No. Observer's Occupation Maneuvers Weather 1 1st Lt, USAF None - horizontal flight Not stated la S/Sgt, USAF Not stated Not stated 1b Unknown Not stated Not stated 1c S/Sgt, USAF Not stated Not stated ld Pfc, USAF Flying in tight circle Not stated le Not stated Horizont…
CONFIDENTIAL
Incident No. Observer's Occupation Maneuvers Weather 10 Capt, United Airlines Straight-away horizontal flight Not stated 11 Coast Guard Horizontal flight Not stated 12 Deputy Sheriff Not stated Not stated 13 Not stated Not stated Not stated 14 Not stated Flipping around Not state…
CONFIDENTIAL
Incident No. Observer's Occupation Maneuvers Weather 30b Traffic Air Controller Bobbing up and down Overcast 30c Not stated Climbing and descending High overcast 31 Professor and Head of Aero Engineering None Clear 32 Lt, USAF None Overcast 33 T/Sgt, USAF None High scattered clou…
CONFIDENTIAL
Incident No. Observer's Occupation Maneuvers Weather 41 Colonel, USAF Not stated Not stated 42 Major, USAF Not stated Not stated 43 Bus Driver None Not stated 44 Not stated None Not stated 45 Not stated Not stated Not stated 46 Not stated None Cloud banks. 47 Captain, USAF Rolled…
CONFIDENTIAL
Incident No. Observer's Occupation Maneuvers Weather 57 Bridge Construction Not stated Clear and dark. 58 Chief Pilot- Flying service Not stated Not stated 59 Pilot None Not stated 60 Storekeeper Not Stated Clear at dusk 61 Not stated None Not stated 62 Not stated Not stated Clou…
CONFIDENTIAL
Incident No. Observer's Occupation Maneuvers Weather 77 Astronomer Not stated Not stated 78 Lt, USN (P80 Pilot Not stated Not stated 79 Weather reporter Not stated Clear 80 Lt. Col, USAF Not stated Scattered clouds visibility 10-12 miles. 81 Civil Service Employee Ascending slowl…
CONFIDENTIAL
Incident No. Color Shape Size Sound 1 Silvery Not stated Not stated Not stated la 1b lc Silvery Saucer shaped Not stated None ld Reflected the sun's rays Disc Not stated Not stated le Silvery Disc Not stated None 2 Aluminum colored surface Thin metallic object, unconventional sha…
CONFIDENTIAL
Incident No. Color Shape Size Sound 11 White Saucer Not stated Not stated 12 Not stated Like flock of geese Not stated Low humming sound 13 Resembled metallic Not stated Not stated Not stated 14 Like a new dime Like a new dime Like a new dime Not stated 15 Silver Not stated Not s…
CONFIDENTIAL
Incident No. Color Shape Size Sound 30a Amber Round or oval C-47 airplane None 30b Bright white to amber Cone-shaped, blunt on top and tapering off toward bottom Enormous None 30c White (light) Round Comparable to runway light None 31 White Not stated Not stated None 32 Amber Not…
CONFIDENTIAL
Incident No. Color Shape Size Sound 39 Phosphorus Egg-shaped discs Not stated Not stated 40 Gray Elliptical 20-00 ft. Noise like jet aircraft prior to its appearance. No audible sound heard while object was in view. 41 Aluminum Round 3 ft. diameter Not stated 42 Grayish Balloon 1…
CONFIDENTIAL
Incident No. Color Shape Size Sound 50 Stated as queer light. Referred to as saucer but not stated as being of this definite shape. Not stated Not stated 51 Silver Round Not stated Not stated 52 White, shiny Circular like a ball on the bottom but not completely round. 15-25 ft Di…
CONFIDENTIAL
Incident No. Color Shape Size Sound 68 Not stated Disc - appeared to have a tail. 30 ft diameter None 69 White Not stated Not stated Buzzing sound. 70 Not stated Giant fire cracker Not stated Buzzing sound not as loud as a rocket ship. 71 Not stated Not stated Not stated Not stat…
CONFIDENTIAL
Incident No. Color Shape Size Sound 84 Shinny Round Not stated More or less Shrill. 85 Not stated Resembled the XF5U-1. Not stated Not stated 86 Not stated Not stated Not stated Not stated 87 Not stated Not stated Not stated Not stated 88 Not stated Flying disc (not actually desc…
CONFIDENTIAL
Incident No. Exhaust Trail Heading Altitude Ft. Speed Effect on Clouds 1 None 320° 1000-8000 ft. 300 mph Not stated la 1b 1c Not stated Northwest 7500-8000 ft. 350-400 mph Not stated ld Not stated Northwest 7000-8000 ft. 300-400 mph Not stated le Not stated Northwest 8000 ft. 300…
CONFIDENTIAL
Incident No. Exhaust Trail Heading Altitude Ft. Speed Effect on Clouds 12 Not stated Not stated Not stated Not stated Not stated 13 Not stated 3 west to east. 1 north Did not appear very high Traveling so fast they were out of sight in east in 2-4 seconds Not stated 14 Not stated…
CONFIDENTIAL
Incident No. Exhaust Trail Heading Altitude Ft. Speed Effect on Clouds 25 Not stated East High Fast Not stated 26 Bluish-black Not stated Not stated Not stated Cut a clear path through clouds 27 Bluish-black 15 mi. long Not stated 10-00 ft. Fast Seemed to cut clouds open 28 Not s…
CONFIDENTIAL
Incident No. Exhaust Trail Heading Altitude Ft. Speed Effect on Clouds 33c Not seen Appeared to be stationary. Very high. Appeared to be stationary. None 33d None 210° from Godman Fld. Uncertain- very high. Stationary. Could be seen through cirrus 33e None 210° from Godman Fld. 2…
CONFIDENTIAL
Incident No. Exhaust Trail Heading Altitude Ft. Speed Effect on Clouds 48a Very faint exhaust trail when moving. S/W when it left the vicinity. Not stated Left vicinity at very high speed. Not stated 48b Greenish mist when descending. S/W when it left the vicinity. Not stated Not…
CONFIDENTIAL
Incident No. Exhaust Trail Heading Altitude Ft. Speed Effect on Clouds 57 Not stated NNE (30° E of true North on horizonal plane. 30° off the horizon at an estimated 1/4 mile range. High velocity, stated to be faster than a tracer bullet. Not stated 58 Not stated N/W 10-00 510 mp…
CONFIDENTIAL
Incident No. Exhaust Trail Heading Altitude Ft. Speed Effect on Clouds 72 None South Below 10-00 Tremendous Not stated 73 None Easterly approximately 110° magnetic. 7000 175 mph Not stated 74 Not stated Not stated Not stated Greater than anything ever witnessed. Not Stated 75 Non…
CONFIDENTIAL
Incident No. Exhaust Trail Heading Altitude Ft. Speed Effect on Clouds 90 One witness thought he saw vapor trails Northerly 8000-10000 Not stated Not stated 91 Not stated Disappeared in the southwest Great height High rate of speed Not stated 92 Not stated West Above 10-00 Great…
CONFIDENTIAL
NOTE: Incident #18 It has now been definitely determined that both the photograph and story were a hoax, perpetrated for publicity and money. Incident #84 The person making the report on this incident was determined to be an excitable person, very talkative, and possessing an…
CONFIDENTIAL
REPORTED DIRECTIONS OF FLIGHT NW 63 N 38 NE 9 W 5 E 22 SW 14 SE 22 S 34 Circling 15 Straight down 3 Direction indefinite 64 Direction Not Stated 61 Where an undetermined number of objects were reported the minimum number of objects are plotted. Same object reported by differen…
ONFIDENTIAL CONFIDENTIAL NND 927545
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CONFIDENTIAL Identification of Subject Matter (as per sample) MCIA MCIT 19 Feb 48 1 1. Reference is made to the films taken by Mr. Rhoades (Incident #40) which were forwarded for examination. The following data were derived from a study of the specimen: a. It is concluded tha…
CONFIDENTIAL CONFIDENTIAL NND 927545
CONFIDENTIAL NND 927545
THE AEROPLANE
THE AEROPLANE FEBRUARY 13, 1948 185 The Biology of the Flying Saucer-I The Story of Low Aspect Ratio Aircraft By A. R. Weyl, A.F.R.Ae.S. SEVERAL MONTHS AGO people on both sides of the Atlantic rushed into print with claims of having observed queer saucer-shaped aircraft which fl…
THE AEROPLANE
THE AEROPLANE 186 FEBRUARY 13, 1948 favour of the "well-tried" convention of "normal" wings. For these reasons, a study of the history of the use of low aspect ratios in wing design will be of interest. Spiritually, the fathers of such aeronautical exhibits were Englishmen. They…
THE AEROPLANE
FEBRUARY 13, 1948 187 THE AEROPLANE flight of Kitchen's models, however, convinced Cedric Lee that an aeroplane of such design would be a success, and late in 1910 he acquired the patents. At the same time, G. Tilghman Richards, who was a qualified aeronautical engineer, became…
THE AEROPLANE
MARCH 5, 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. (Contin…
THE AEROPLANE
THE AEROPLANE 280 MARCH 5, 1948 Fig. 11. Willoughby's "Delta 8" experimental monoplane of 1938. Thus, an observant student of laboratory tests could have noticed the extraordinary capacity of circular or square shapes to give a very gradual, innocent stall, and that at very hig…
THE AEROPLANE
MARCH 5, 1948 281 THE AEROPLANE Fig. 14. A Russian parabola' glider of 1924. extensive wind-tunnel investigation and the published reports still form the basis of present development. In places, the results confirm, qualitatively, the experiments made 20 years before. But, as m…
THE AEROPLANE
THE AEROPLANE 282 MARCH 5, 1948 and pseudo-circular and pseudo-square wings thus exhibit significant d.fferences. This also applies to the ground effect, i.e., the land.ng qualities. The provis.on of oblique nozzle-shaped slots at the tips yielded no useful results. In any CASE,…
THE AEROPLANE
MARCH 19, 1948 337 THE AEROPLANE The Biology of the Flying Saucer-III By A. R. Weyl, A.F.R.Ae.S. Previous articles in this series appeared in "The Aeroplane" for February 13 and March 5 WIND-TUNNEL TESTS were made in Turin and at Rome of five Canova projects (described in the pr…
THE AEROPLANE
THE AEROPLANE 338 MARCH 19, 1948 Fig. 21. Lift curves of aerofoils of different aspect ratios. (Left) Wind-tunnel results obtained, in 1920, at Goettingen, with Goettingen 389 aerofoil and square tips. The absence of stall at normal incidence is in evidence, for aspect ratios up…
THE AEROPLANE
MARCH 19, 1948 339 THE AEROPLANE M. B. Morgan has recently communicated the following values for the limit of stability at the stall from this graph:- Upper limit of the Angle of Sweep-back (referred to the chord) beyond which self-stall can be expected Aspect Ratio Required D…
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