Within Fort Belvoir
How a Mock Atomic Blast Made the Ring
Fuel, explosives and white phosphorus could form a huge toroidal smoke vortex that detached from the blast and drifted across the base.
On this page
- How the demonstration was staged
- Why a toroidal vortex formed
- Why the ring stayed intact and drifted
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Introduction
The famous Fort Belvoir photographs from September 1957 are often remembered as one of Virginia’s most striking “UFO” image sequences. The photographs do indeed show an unusual dark ring drifting across the sky, but later investigation found that the ring was not an unknown aerial object. Instead, it was a smoke vortex created during a military demonstration designed to simulate the effects of an atomic explosion. Army personnel familiar with the demonstrations explained both how the ring formed and why it could remain intact long enough to be photographed. Their explanation became one of the strongest documented identifications of a celebrated UFO photograph.[NCAS Files]files.ncas.orgFiles Condon Report, Case 50: Ft Belvoir "Atom Bomb DemonstrationNCAS FilesCondon Report, Case 50: Ft Belvoir "Atom Bomb Demonstration"…
Rather than relying on speculation, investigators reconstructed the physical process behind the phenomenon. The mechanism itself is the key to understanding why witnesses initially mistook the ring for something solid and why the photographs appeared so convincing.
How the demonstration was staged
Fort Belvoir regularly conducted “atomic bomb simulation demonstrations” during the 1950s for military visitors, engineers and officials. These were intended to illustrate the visual effects of a nuclear detonation without using nuclear weapons.
According to Army personnel interviewed during the investigation, the demonstration used five 55-gallon drums arranged in a circle. The drums contained a combination of gasoline, diesel fuel, TNT and white phosphorus. When detonated together, the explosion produced:
- a rapidly expanding fireball;
- a rising mushroom-shaped cloud;
- dense black smoke from the burning fuel; and
- white smoke generated by the burning white phosphorus.
The investigators did not discover this explanation by working backwards from a preferred conclusion. When they visited Fort Belvoir years after the photographs were taken, Sergeant-Major A. M. Wagner independently recognised the images as the by-product of these demonstrations before investigators explained their own theory. Another instructor, Sergeant-Major A. Husted, then described the construction of the explosive display in detail and showed where the demonstrations had been conducted. The photographed ring was drifting directly away from that location, matching the expected wind direction.[NCAS Files]files.ncas.orgFiles Condon Report, Case 50: Ft Belvoir "Atom Bomb DemonstrationNCAS FilesCondon Report, Case 50: Ft Belvoir "Atom Bomb Demonstration"…
Why a toroidal vortex formed
The most unusual feature of the demonstration was not the explosion itself but the behaviour of the smoke immediately afterwards.
As the hot gases from the blast rose, the outer edges of the smoke column rolled back on themselves. This rolling motion created a toroidal vortex—a doughnut-shaped ring of rapidly rotating air and smoke, similar in principle to a smoker blowing a smoke ring but vastly larger.
The ring did not simply consist of smoke hanging in the air. It was a rotating vortex that continually circulated smoke around its circular structure. This rotation helped maintain its shape, making the ring appear remarkably solid and sharply defined.
Sergeant-Major Husted explained that the black ring was produced mainly by diesel smoke, while the white phosphorus generated a separate white cloud that gradually expanded around it. The six Fort Belvoir photographs capture this sequence: first the sharply defined black ring, then the growing white cloud, and finally the ring disappearing inside an opaque white mass.[NCAS Files]files.ncas.orgFiles Condon Report, Case 50: Ft Belvoir "Atom Bomb DemonstrationNCAS FilesCondon Report, Case 50: Ft Belvoir "Atom Bomb Demonstration"…
A witness to similar demonstrations, Jack Strong, also recalled seeing the ring rotate rapidly around its circular axis. He believed this continuous circulation was largely responsible for the ring’s exceptional stability before it became hidden by the surrounding cloud.[NCAS Files]files.ncas.orgFiles Condon Report, Case 50: Ft Belvoir "Atom Bomb DemonstrationNCAS FilesCondon Report, Case 50: Ft Belvoir "Atom Bomb Demonstration"…
Why the ring stayed intact and drifted
Many smoke rings collapse within seconds, so one obvious question is why the Fort Belvoir ring survived long enough to travel across part of the base.
The Army personnel interviewed during the investigation described several favourable conditions.
First, the ring detached cleanly from the top of the mushroom cloud rather than remaining connected to the rising column. Once separated, it became an independent vortex moving with the prevailing wind.
Second, the vortex was rotating continuously. This internal circulation resisted mixing with the surrounding air, allowing the ring to retain its circular outline much longer than ordinary smoke.
Third, weather conditions mattered. According to Sergeant-Major Husted, some demonstrations produced no recognisable ring at all, while others created nearly perfect circles. Calm, stable air allowed the vortex to remain coherent instead of being torn apart by turbulence. Under especially favourable conditions, he estimated that a ring could remain intact for as long as forty minutes, although many would dissipate much sooner.[NCAS Files]files.ncas.orgFiles Condon Report, Case 50: Ft Belvoir "Atom Bomb DemonstrationNCAS FilesCondon Report, Case 50: Ft Belvoir "Atom Bomb Demonstration"…
The investigation also estimated that the photographed ring was far larger than the witness had originally believed. By comparing the ring’s apparent motion with cloud movement and estimated wind speeds, investigators concluded that it may have been several hundred feet across and thousands of feet from the observer. Comparison photographs from actual demonstration tests showed vortex rings roughly 260–300 feet across shortly after formation, expanding further as they drifted. A diameter approaching 500 feet by the time the ring reached the witness’s position was considered physically consistent with the photographic evidence.[NCAS Files]files.ncas.orgFiles Condon Report, Case 50: Ft Belvoir "Atom Bomb DemonstrationNCAS FilesCondon Report, Case 50: Ft Belvoir "Atom Bomb Demonstration"…
Why the explanation fits the photographs
The smoke-vortex explanation accounts for several details that initially made the photographs appear mysterious.
The witness described the object as extremely black and apparently solid rather than wispy. Dense diesel smoke concentrated within a rotating vortex would naturally produce a darker appearance than diffuse smoke.
The gradual transition from a black ring to a white cloud also matches the demonstration. Investigators noted that the first photographs show a relatively transparent white cloud through which the ring remains visible. Later images show a much denser cloud casting realistic shadows while completely obscuring the black vortex. The changing lighting and opacity followed normal physical behaviour rather than suggesting photographic manipulation.[NCAS Files]files.ncas.orgFiles Condon Report, Case 50: Ft Belvoir "Atom Bomb DemonstrationNCAS FilesCondon Report, Case 50: Ft Belvoir "Atom Bomb Demonstration"…
The object’s steady motion also supported the explanation. Photogrammetric analysis showed that the ring moved with essentially the same direction and angular speed as the background clouds, indicating that it was drifting with the wind rather than flying under its own control.[NCAS Files]files.ncas.orgFiles Condon Report, Case 50: Ft Belvoir "Atom Bomb DemonstrationNCAS FilesCondon Report, Case 50: Ft Belvoir "Atom Bomb Demonstration"…
Why this mechanism matters in Virginia’s UFO history
The Fort Belvoir photographs remain significant not because they reveal an unidentified craft, but because they illustrate how an unusual atmospheric effect generated during military activity could convincingly resemble one.
Unlike many historical UFO photographs, this case was supported by multiple independent lines of evidence. Army personnel identified the demonstration without prompting, investigators located the demonstration site, technical descriptions matched the sequence visible in the photographs, and comparison images of the same training exercise showed identical vortex formation. Although investigators briefly considered whether some photographic retouching might have enhanced one image, they concluded that the overall event itself had been positively identified as the product of Fort Belvoir’s bomb-simulation demonstrations rather than an unexplained aerial phenomenon.[NCAS Files]files.ncas.orgFiles Condon Report, Case 50: Ft Belvoir "Atom Bomb DemonstrationNCAS FilesCondon Report, Case 50: Ft Belvoir "Atom Bomb Demonstration"…
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Endnotes
1.
Source: files.ncas.org
Title: Files Condon Report, Case 50: Ft Belvoir “Atom Bomb Demonstration”
Link:https://files.ncas.org/condon/text/case50.htm
Source snippet
NCAS FilesCondon Report, Case 50: Ft Belvoir "Atom Bomb Demonstration"...
2.
Source: files.ncas.org
Title: Files Condon Report Section III, Chapter 1: Field Studies
Link:https://files.ncas.org/condon/text/s3chap01.htm
Source snippet
An indication of the manner in which representatives of the Air Force dealt with the photographer, after the original UFO report was subm...
3.
Source: files.ncas.org
Title: Files Condon Report Section III, Chapter 2: Photographic Evidence
Link:https://files.ncas.org/condon/text/s3chap02.htm
Source snippet
NCAS FilesCondon Report Section III, Chapter 2: Photographic Evidence...
4.
Source: files.ncas.org
Title: * * * | | LETTER OF TRANSMITTAL
Link:https://files.ncas.org/condon/text/contents.htm
5.
Source: files.ncas.org
Link:https://files.ncas.org/condon/text/s3chap05.htm
6.
Source: files.ncas.org
Link:https://files.ncas.org/condon/text/case52.htm
Additional References
7.
Source: nationalacademies.org
Title: Read “Toxicity of Military Smokes and Obscurants: Volume 2” at NAP.edu
Link:https://www.nationalacademies.org/read/9621
Source snippet
January 1, 1999 — To assist with this effort, the Army requested the National Research Council (NRC) to independently review the availabl...
Published: January 1, 1999
8.
Source: ntrs.nasa.gov
Link:https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050196658.pdf
Source snippet
Rings Generated by a Shrouded Hartmann-Sprenger Tube - NASA Technical Reports Server (NTRS)July 1, 2005 — NTRS NTRS - NASA TECHNICAL REPO...
Published: July 1, 2005
9.
Source: gbppr.net
Link:https://gbppr.net/reanalysisofthe1965heflinufophotos.pdf
Source snippet
Journal of Scientific Exploration, Vol. 14, No. 4, pp. 583–622, 2000...
10.
Source: youtube.com
Title: What Are Those Mysterious Black Rings All Over the World?
Link:https://www.youtube.com/watch?v=BhJFYRyjvoA
Source snippet
Smoke Bomb Smoke Rings - Cool Science Experiment...
11.
Source: youtube.com
Title: Ominous Smoke Ring in Sky Likely Has Easy Explanation
Link:https://www.youtube.com/watch?v=CsEzsnzSQJk
Source snippet
The Condon Report | NASA's Unexplained Files...
12.
Source: dtra.mil
Link:https://www.dtra.mil/About/Mission/Nuclear-Test-Personnel-Review/US-Atmoshperic-Nuclear-Test-History-Documents/
13.
Source: scribd.com
Link:https://www.scribd.com/document/192717159/Final-Report-of-the-Scientific-Study-of-Unidentified-Flying-Objects
14.
Source: youtube.com
Title: The Science of Vortex Rings
Link:https://www.youtube.com/watch?v=yjgACB7urOo
Source snippet
What Are Those Mysterious Black Rings All Over the World?...
15.
Source: youtube.com
Title: The Condon Report | NASA’s Unexplained Files
Link:https://www.youtube.com/watch?v=_W7SqS6UhE4
Source snippet
The Science of Vortex Rings...
16.
Source: scribd.com
Title: Condon Report | PDF | Cloud | Sky
Link:https://www.scribd.com/document/718800974/Condon-Report