Photo analysis and text prepared by Dr. Richard F. Haines

Investigated by Francis Ridge, Linda Dahlkemper, Bruce Engstrom, Robert Taylor,
Roger Sugden and John Timmerman


Eight adult witnesses saw a self-luminous disk fly across the sky at a campground in northern Indiana at 9:30 pm (EDT) on August 31, 1994 on a clear dark night. Five 35 mm color photographs were taken over about a 25-second interval with a Kodak K-40 camera. Four of the frames show an angularly large object. This paper describes the results of measurements, calculations, and various digital quantifications. Knowledge of the approximate maximum distance from two different ground vantage points and the angular size of the aerial object shows that it was about 19 feet in length and 8.5 feet thick (at an assumed range of 2300 feet). Further analysis suggests the object traveled approximately 3900 feet over a 30-second time span. Assuming a constant velocity; its ground speed would have been approximately 192  mph significantly faster than a blimp can fly in calm air. The suggestion that the object was an internally illuminated advertising blimp is rejected on other grounds as well. The object remains unidentified.

DIGITAL IMAGE ANALYSIS RESULTS: Frames 4-7 were scanned with a LaCie Ltd., Silver Scanner II and analyzed by Dr. Richard F. Haines using Adobe Photoshop software on a Power Macintosh model 7100/66. 

THE ADVERTISING BLIMP HYPOTHESIS: It was suggested that the UFO was an internally illuminated advertising blimp on the basis of the fact that a blimp definitely was in the area that evening (Anon., 1994 [a]; Anon., 1994 [b] and similarities in general shape of video images obtained previously in other geographic locales by several people (Kelley,1995; Sainio, 1993). We will evaluate this suggestion in light of each piece of evidence. Mr. J. K. said that he went hunting the next day and saw the "Family Channel Blimp" flying nearby. He remarked to the investigator, Francis Ridge, "There's no way in hell (that) we saw a blimp that night." As will be seen, several different avenues were followed to test this personal assessment by the eyewitness. 

BASIC BLIMP CHARACTERISTICS: Francis Ridge and Mr. John Timmerman of the J. Allen Hynek Center for UFO Studies (CUFOS) separately contacted various lighter-than-air ship manufacturers for specifications, illustrations, and flight schedules. Figure 12 (not shown here) is a drawing of the "Lightship" built by the American Blimp Corporation of Hillsboro, Oregon. Four variations are sold which vary in length but not in width-to-length ratio. The overall length of the A- 150 model is 128 feet and its maximum diameter is 30' 10" for a width to length ratio of 0.24 (about one-half of the measured width to length ratio of the UFO seen in frames 4 and 5; viz. 0.444 and 0.452, respectively). One shorter and two slightly longer models than the A-150 are manufactured by this company. The top speed of this model is 55 mph using two 68 hp German Limbach engines, each operating at 2900 RPM. 

The maximum rate of climb for this blimp is 1600 feet per minute and 1400 fpm maximum rate of descent. Its rated service ceiling is 7800 feet and maximum range without refueling at 40 mph is 560 nautical miles. Its minimum turn radius is 375 feet. Needless to say, its ability to accelerate is very limited. More importantly, the outer skin of these blimps is made from a tough woven fabric and plastic film that is translucent. Spotlights located inside it make the entire blimp glow relatively evenly. The advertising panels on the sides of the blimp do not move relative to the blimp itself but are attached by numerous tie-down cords. 

Figure 1
  Larger image of Figure 1 (Map of area)

A blimp was in the area. (Ridge: "One newspaper account said that The Family Channel blimp was responsible for reports in northern Indiana at that time.") Kelley (1995) reported that a blimp owned by the Virgin Lightship Co. (Orlando, Florida) traveled from Minneapolis, Minnesota to Lakehurst, New Jersey in 31 hours, including that evening. 

No sound heard. If a blimp was the source of these photographs its reciprocating engines would probably also have been heard at distances under about 2,000 to 3,000 feet in the calm night air. No such sounds were heard by anyone. 

Blimp shape. Several previously recorded VHS segments of positively identified blimps were analyzed by Jeff Sainio, chief photo analyst for MUFON. He provided the author with a copy of these VHS clips and still frame photographs for comparison with the present photographs. While they appear to be similar in shape to the present images they also differ in interesting ways. 

Figure 14 (not shown here) shows three consecutive 1/30 sec. video frames from a camcorder recording taken by Mr. John Stanolevich on August 23, 1995 at Rego Park (near Shea Stadium), New York, which were conclusively identified as an advertising blimp. These three video frames show: (A) the one-flash-per-second white, anti-collision strobe light on the bottom appearing as a bulge beneath the oval-shaped object. Each flash is seen in only one frame indicating that its duration is less than 1/30th of a second. (B) and (C) the generally oval-shaped blimp image is composed of several horizontal (raster) TV lines separated by blank lines whose ends stair-step in order to produce the overall image. The overall width to length ratio of these images is 0.42 and no prominent dome is seen on the top.

The Virgin Lightship Co.  blimp

Contradictory film image size. If the object was one of the American Blimp Corporation airships (128 feet long) for instance, it would have had to be 21,395 feet (about 4 miles) away to produce the small image length found on these photographs! This large a distance contradicts the testimony of the main group of witnesses at the campsite, as well as that of two hunters who said they saw the object to the north of their estimated position. 

Other arguments. 1) the lack of any visible protuberance on the top of the blimp which is clearly visible in all of these photographs, 2) the presence of a small gondola below the blimp which is hot visible on these photographs, 3) the presence of a dark, opaque (structural) tip at each end of these blimps which is not seen in any of the eyewitness drawings or photographs. 4) the probable average velocity calculations presented below tend to exceed the maximum ground speed of a blimp, 5) the reported high acceleration departure exceeds the capability of blimps, 6) only one of the six witnesses at the main campground saw a flashing light on the object as it departed to the SE. However, FAA approved anti-collision strobe lights on flight certified blimps must be visible from all possible viewing positions relative to the blimp so that everyone in the group should have seen the strobe light.

B & W print of frame 4, scanned at 600 dpi

The results presented in Table 6 (not shown) also support the opinion of Mr. J.K. wherein the angular size of a 128-foot-long blimp was calculated for each of four hypothetical viewing distances. The length of the image of the object on the original negative represents only 0.86 percent of the width of the frame which is considerably smaller than any of the values given in Table 6. 

Finally, the majority of blimps have a width to length ratio of from 0.25 to 0.30 which is approximately one-half of the ratio of the present aerial object (not including its dome on top). 

Discontinuous object motions. All but one of the main group of witnesses indicated that the object wasn't a blimp. It moved relatively fast, stopped, changed directions (appearing to approach the witnesses), stopped again, and then accelerated away in a matter of seconds. Blimps do not behave this way! 

Object velocity. Assuming certain values for total distance traveled (d) and sighting duration (t), object velocity can be calculated. Mr. J. K. thought the sighting lasted about 15 seconds while D. B. had a longer estimate of from 60 to180 seconds. The other three primary witnesses (one of the six did not report) did not make temporal duration estimates. The total horizontal angle through which the object traveled (as measured from the main campsite) is approximately that shown in Figure 1, although its distance from the observers is not known for sure.

Assuming the flight path of the object was that shown by the heavy dashed line in Figure 1 and it was in sight for t = 60, 90, or 120 seconds, its average (constant) velocity is 65.3, 43.5, or 32.6 ft/sec, (95.3, 63.8, or 47.9 mph), respectively. Only the slowest of these values is within the 55 mph maximum speed of the commercially produced Lightship Blimp discussed above. If the actual flight path of the object was far more of an acute angle V with its initial and final distances much greater than are shown in Figure 1, i.e., an assumed total flight path length of about 10,740 feet, with the nearest point as illustrated, the object's average velocity (also assuming a constant velocity) for t = 60, 90, or 120 seconds would be 262.175, or 131 mph, respectively. All of these velocities are significantly faster than this blimp can fly. And so for a blimp, comparable to the Lightship Blimp, to have caused this report it would have had to do all of the following: 1) fly at its maximum speed and never stop moving, 2) fly along the approximate path shown in Figure 1 or nearer to the campsite. 3) remain in sight for about a hundred seconds or more (traveling at a constant speed), 4) somehow appear to accelerate at a high rate of speed, and 5) remain silent the entire time! Since most of the witnesses said that the object moved discontinuously and actually seemed to stop once or twice, its actual velocity would have had to be even faster than calculated above to make up for the time it had stopped. Finally, no witness indicated that the object changed shape. If it were a blimp and changed heading, its length would seem to shorten somewhat without changing thickness. 

The self-luminous aerial object seen and photographed at Mongo, Indiana on August 31, 1994. has remained unidentified after the various evaluations cited above. On the one hand. its overall shape and flight characteristics are not unlike many scores of other UFOs reported for more than fifty years from around the world, many of which were captured in photographs. On the other hand, a blimp definitely was seen during the night of August 31, 1994 in the Mongo area. The aerial object photographed cannot be positively identified at this time. It remains a UFO. 

We have been unable to obtain any official flight records for any blimp flights explaining the Mongo event. Two different blimp companies were "identified" (Family Channel & Virgin Lightship) by "authorities." A current and separate investigation is underway involving a video taken the same evening at Hamilton, Indiana, just a few miles SE of Mongo! The witnesses also claim the object at one point was less than 100 feet over them, was as big as a football field, and made no noise! 

Source: MUFON UFO JOURNAL, Number 334, February 1996

Mongo Case Directory