Case 50

Fort Belvoir U.S. Army Facility, Va.

September 1957

Investigator: Hartmann

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PLATES for this Case


A black ring that became obscured by an opaque white cloud, reportedly witnessed by about 15 persons and photographed by the principal witness, is identified as the by-product of an "atom bomb simulation demonstration" on the army base.


Time: Approx. 9 a.m.

Position: Looking NNE past building T741, Fort Belvoir, Va.

Terrain: Gently rolling hills with scattered technical buildings, residential areas, and woods.

Weather Conditions: Exact date unknown; hence weather conditions unavailable. Photographs show scattered cloud cover.

Sighting, General Information:

Private X, who worked as a draftsman with Post Engineers (1), has given the following account of the visual and photographic sighting. He was in one of several buildings facing on a parking lot flanked by buildings T741 and T742 (1,3). Someone from the outside called for the men to come out and see the curious object approaching overhead. Pvt. X and several others came out in time to see a dark, ringshaped object approaching in the north. He ran to his car in the parking lot and got his Kodak Brownie camera (1,2,5).

Pvt. X thought the black ring "seemed solid," as opposed to being "like smoke" (2), although he also stated that it was not metallic, shiny, or dull, but very black with no reflection (1).


He estimated that the ring was about 60 ft. in diameter and five to six feet thick (2,5). He felt that it moved systematically faster than the clouds (1), and was "high above the treetops," but below the clouds (2). It did not stop or hover, but moved continuously (1) and horizontally (2). Standing in one spot as well as he can recall (1), Pvt. X took six photographs of the UFO (Plates 32 - 37). Between taking the second and third, the black ring began to be "engulfed in smoke" (2), though Pvt. X does not remember seeing how this happened; he believes he was distracted by winding the film of his camera at that time (1). Sources 1, 2, and 5 are in agreement with regard to the circumstances and description of the UFO (All three references resulted from interviews with Pvt. X.)

The duration of the sighting was estimated at not more than five minutes (1), with perhaps 30 - 60 sec. required for the black ring to become enveloped by smoke.

Roughly 15 men saw the phenomenon, and at least two photographed it (1). Pvt. X did not know any of these men personally, as he had recently been assigned to work in this building. Efforts to locate other witnesses were unsuccessful. After watching the cloud for a while, the men returned inside without waiting to see what became of it. There was a feeling at this time that perhaps the object represented some kind of secret test (1,2,5).


Pvt. X believed that the object was connected with some sort of test or experiment and that it perhaps should not have been photographed. As a result he made no inquiry or report at Fort Belvoir and did not have his photographs developed until a month after the incident when he had returned home (1,2,5). He notes, "I was only a private in the Army...the only thing mentioned was that it was strange and maybe someone was experimenting so we didn't tell anybody that we even took these pictures...1 didn't want to get in trouble so when I came home I had the pictures developed then" (2).


Pvt. X had changed his residence five or six times since the photos were made and the original negatives have been misplaced. He still has the camera, a Brownie holiday, purchased in 1957 (1). He showed the photographs to various friends, whose reaction was typically a mixture of joking and scoffing. Finally, in the spring of 1966, he showed them to a friend who sent the photographs to NICAP with an inquiry. Dr. James McDonald became interested in them in mid-1966 and called them to our attention. In view of the excellent photographic material we gave them a high priority.

With regard to the sighting Pvt. X has been an intelligent and interested advisor. His suggestions for locating other witnesses indicated a sincere attempt to be helpful in shedding light on the affair.

Photographic analysis. A preliminary analysis was carried out on this case on the basis of which it was regarded by us as potentially interesting. The early tests are briefly described as examples of the kind of analysis which allowed us to classify UFO reports as potentially important, verifiable, and/or explicable.

Consistency with observer's report. The photographs all overlap on a large tree whose complex foliage shows no parallax whatsoever verifying Pvt. X's statement that all photographs were taken from one spot. This was later determined to be in the middle of the parking lot near Pvt. X's building. By overlapping and "blinking" the six exposures, motions of the background clouds could be followed from Plates 34-37. The numbering of the photographs was found to be consistent with the motion of the clouds. A montage showing the object and cloud motions in the six frames is shown in Fig. 5 . it is significant that the relative spacings of both UFO and cloud positions are the same; this is an argument against a fabrication created by sketching an object on six photographs, because such a fabrication would require a certain sophistication on the part of the artist.


Fig 5

Figure 5: Mosaic of Photos

Click on thumbnail to see full-size image.


The relatively long pauses after exposures 1 and 2, and the sudden burst of exposures 3 and 4, followed by the somewhat slower pair 5 and 6, are judged to be psychologically consistent with the sudden observation that the remarkable black ring was being enveloped, even more remarkably, by a white, misty cloud before exposure (3).

Geometric and physical tests; Inclination vs. altitude. If a flat disk or ring moves with its plane parallel to the ground (the mode of flight usually associated with "flying saucers"), the observed inclination angle (observer-center-rim) should equal the observed altitude. One initial hypothesis was that these photos could represent optical fabrication with an image drawn in on photographs made earlier. It was important to test the geometric consistency of the images with tests more sophisticated than might be expected of a hoaxer. Table 4 shows the results of these measures.

Table 4

Inclination vs. Altitude

Photo Inclination Altitude Pitch Angle
1 19.9° 16°
2 42.0 31 11
3 46.8 47 0
4 48.1 48 0
5 49.0 49 0
6 49.1 51 2

Only in Plate 33 does there appear to be a significant departure from level flight. From the apparent attitude of the ring in this photo it is judged to be out-of-level not only in the vertical plane of UFO observer, but in the vertical plane perpendicular to this. Nonetheless, it is concluded that the ring and disk-cloud can be described as oriented essentially horizontally, with some "wobble"-like perturbations.


Distance vs. angular size. If the linear diameter of the UFO is D and the angular diameter Delta, and if its vertical height is Z and its altitude Alpha, then (if Delta is small),

sin Delta
sin Alpha
= D

if the UFO moves along a path roughly parallel to the ground. One has a subjective impression, both from the testimony and from the photos, that this was the motion in this case. Table 5 shows the results of measures of this sort (made with a millimeter scale on prints). It is concluded that within tolerances of 7%, the object did move on a path roughly parallel with the ground, although it may have been slowly rising and expanding.

Table 5

= sin Delta
sin Alpha

Photo sin Delta
sin Alpha

1 .181
2 .170
3 .141
4 .147
5 .146

Illumination properties. Another item of evidence against an optical fabrication is the subtle consistency between the illumination of the cloud and the laws of physics. In Plate 34 when the cloud is first forming, it is tenuous. The optical depth is low, so that we can still see the dark ring inside quite clearly. The sunlight is coming from the upper right. If the optical depth is low, the sunlight must pass through the cloud with only moderate diminution. Hence, no strong shadows can be formed on the "dark" side of the cloud, as is shown by the photograph.


Plates 35 through 37, the cloud develops and becomes opaque. The dark ring becomes invisible, and a cumuloform structure can be seen. In Plate 37, the cloud is quite white and opaque, like a dense cumulus cloud. The optical depth is great; the sunlight must be absorbed and shadows must form. This is also shown by the photograph.

It is unlikely that had the prints been fabricated by using airbrush, the artist would have thought, even intuitively, to establish this consistency. This test, like the others, leads to the conclusion that the data are consistent with a real object becoming enveloped first in a tenuous, then in an opaque, cloud.

The fact that the six photos overlap lends interest to the case, relative to cases with markedly different backgrounds in allegedly continuous photo sequences. The rather subtle discovery of the cloud motions in the sky background confirmed that the photos were definitely taken in the order reported. The fact that the UFO spacings were consistent with the cloud spacings gives no support to the hypothesis of an optical fabrication with a drawn-in-image. The psychological consistency of the spacing of exposures adds credibility.

Finally, and perhaps most significant, the UFO was moving with a vector motion approximately equal to the background cloud vector motion; i.e. the directions and angular velocities were about the same. This at once suggested that the whole apparition was drifting with the wind, a conclusion consistent with the appearance of the smoky cloud.

Estimate of dimensions of UFO. Since the approximate velocity and height of the background clouds and the time intervals between photos are known, one can derive an approximate distance, hence size, for the UFO as a function of the UFOs height by using the observed cloud and UFO angular velocities. Although the exact date is unknown and therefore weather data were unavailable, we need only order-of-magnitude data, since the UFO dimensions are a priori quite unknown. A geometric model and estimated parameters


were used in this way to estimate the diameter and distance of the ring. The observation that the UFO drifts smoothly and in approximately the same direction and with the same angular velocity as the clouds makes reasonable an assumption that the UFO is at an appreciable fraction of the height of the clouds, and large and high enough to be out of the region of ground eddies.

With these assumptions, using 20 mph as the wind velocity at cloud height, and various reasonable values for cloud height and time intervals, the assumption that the object was higher than one-tenth the cloud height, allows a rough estimation of the ring diameter as 30 - 600 ft. Once again, the conclusion was that all the data are compatible with a large, unusual, real object.

The case had come originally through Dr. James McDonald from NICAP. Although we made no effort to publicize it, it was described in a magazine article by Ralph Rankow (1967). Rankow presented it as a complete mystery, but his article generated a letter from Jack Strong, graduate student at the University of Wisconsin, who said that he had been present at bomb demonstration tests at Ft. Belvoir, and described clouds from such tests. At this time the suggestion was not taken very seriously, as none of those involved imagined that such a phenomenon would be produced by an explosion.

Sergeant-Major A. M. Wagner, interviewed at Ft. Belvoir, immediately identified the pictures as showing a cloud produced by "atomic bomb simulation demonstrations" which were frequently carried out at Ft. Belvoir for visiting officials and military cadets. This identification was made without mention of such a hypothesis. Before the geometry of the situation was discussed, Sgt-Major Wagner showed a map of the base and the location o1 the bomb demonstration site. It was clear that the ring and cloud in the photographs were drifting radially away from this site (see Fig. 6).


Fig 6

Figure 6: Ft Belvoir Map

Click on thumbnail to see full-size image.


Sergeant-Major A. Husted further confirmed this and described the technique of the explosion. Five 55-gal. drums of gasoline, diesel fuel, TNT, and white phosphorus are arranged in a circle and detonated. The blast throws up a fireball enveloped in black smoke. The top of the mushroom cloud is a stable vortex ring, which ultimately drifts away. Depending on the weather and explosion conditions, this ring sometimes never forms at all and at other times forms a perfect, persistent circle. According to Sergeant-Major Husted, the white phosphorus produces a white smoke that eventually envelopes the black vortex produced by the diesel fuel. He estimated that the vortex occasionally held together as long as 40 min.

Strong, who believes he witnessed the same vortex that was photographed in this case, makes the following remarks: "I recall that the ring could be seen to revolve rapidly up to the time that the developing cloud had obscured details. By 'revolve' I mean, of course, motion about the centerline of the vortex [not around the vertical axis]. I don't recall the direction of this revolution, whether upward or downward through the center...This rapid rotation, along with the calmness of the air, probably had a lot to do with the great stability and symmetry of the vortex."

Photographs of one of the tests were obtained through Sergeant-Major Husted. Plates 38, 39 , and 40 were made by Sergeant First Class James O'Dell and show the early stage of such a test, up to production of the independent black vortex.

The dimensions of the ring are estimated from the O'Dell photographs to be as follows: diameter ~200 ft. for the fireball in Plate 38, and 260-300 feet outside diameter for the ring in Plate 40. From the angular diameters of about 6° in Plates 32-37, and the estimated line-of-sight distance of 5,000 ft., a diameter of about 500 ft. is derived by the time the ring was passing near the witness. These figures are consistent with the expected expansion of the ring, and with the estimates made from the photographs (Plates 32-37) alone.


There are, on the other hand, some indications of possible fabrication of the photographs. Upon close inspection, Plate 33 reveals a set of radial scratches or striations around the outer and inner borders of the black ring. Each mark is of length comparable to the width of the ring; the pattern is reminiscent of iron filings near a magnet. It is conceivable that these marks represent a retouching of the original vortex ring to make it appear more regular and thus more puzzling. It is also conceivable that these are a natural step in the formation of the white cloud. In view of the positive identification of the entire event and consequent irrelevance to UFOs, this question was not pursued further.


In the light of identifications both by officials at Fort Belvoir and other technically competent observers familiar with the event, this case is considered positively identified as an atomic bomb simulation demonstration of the type commonly carried out at Fort Belvoir during this period.

The fact that this case did not come to light until nine years after it occurred because the witness was afraid of ridicule or possible reprimand for military security breaches testifies to the reality of the "hidden data" problem in UFO studies.

Sources of Information:

  1. Hartmann, W. K. (24 May 1967), Telephone interview with Pvt. X.
  2. NICAP file on Ft. Belvoir incident, consisting of correspondence and interviews with Pvt. X.
  3. Hartmann, W. K. (21 Dec. 1967), Interviews with staff personnel, Ft. Belvoir, Va.
  4. Klass, Phillip J. (1967), Miscellaneous correspondence with Hartmann regarding Ft. Belvoir incident.


  1. Rankow, Ralph "The Ring-Shaped UFO," Flying Saucers, No. 4, (Fall, 1967).
  2. Correspondence between Dr. James McDonald and Jack Strong, University of Wisconsin.