Feb 19, 2019 I Micah Hanks

Ruppelt’s Mystery Deltas: Evidence of Project Blue Book-Era Stealth Aircraft?

Project Blue Book has been all the rage lately, with the popularity of History’s eponymous program based loosely on the real-life USAF UFO study, and its equally real science advisor, J. Allen Hynek. (Apparently, the show has been really popular, since it was recently announced that the saucers have been cleared for landing… landing another season, that is.) 

However, all the interest in Project Blue Book lately has brought something to mind from the Blue Book years that has always bothered me.

More on that in a moment. To lead off, I’ll quote an interesting passage from Bill Yenne’s excellent book Area 51 Black Jets: A History of the Aircraft Developed at Groom Lake, America’s Secret Aviation Base, in which he brings to mind a question that has remained on many minds since the beginning of the UFO era: how many of the “unknowns” are actually ours?

Bill writes:

One area where the interests of the black airplane and flying saucer enthusiasts has intertwined is in the suggestion that the flying saucers actually were black airplanes, disc-shaped craft created here on earth. Back in 1947, General Nathan Twining had mentioned a "possibility that these objects are of domestic origin—the product of some high security project not known to [the Headquarters Air Staff]."

If so, what were they?

It’s an interesting question (as is the quote from General Nathan Twining he cites, since Twining, and a particular memo associated with him, have pertinence to some of the most contentious information to arise in relation to UFOs during his era; but that’s a story for another time, and one that’s already all-too-often talked about anyway).

This brings us back around to that issue I had with the Blue Book years, which actually has to do with a report from July 24, 1952, which was described by Edward J. Ruppelt, first chief of Project Blue Book, as being “a good UFO report,” in his words. I’m not here to dispute that, and in fact, I would agree: what we’re about to look at really probably is, as Ruppelt said, a good UFO report… and the very reason why is because I think it may be explainable, at least partially, in hindsight. Hence, it may also be a case representative of a reliable description offered by pilots at the time, who legitimately could not identify the objects they had seen.

In his The Report on Unidentified Flying Objects, Ruppelt describes the incident as follows:

On July 24, 1952, two Air Force colonels, flying a B-25, took off from Hamilton Air Force Base, near San Francisco, for Colorado Springs, Colorado. The day was clear, not a cloud m the sky.


The colonels had crossed the Sierra Nevada between Sacramento and Reno and were flying east at 11,000 feet on "Green 3," the aerial highway to Salt Lake City. At 3:40 P.M. they were over the Carson Sink area of Nevada, when one of the colonels noticed three objects ahead of them and a little to their right. The objects looked like three F-86's flying a tight V formation. If they were F-86's they should have been lower, according to civil air regulations, but on a clear day some pilots don't watch their altitude too closely.


In a matter of seconds the three aircraft were close enough to the B-25 to be clearly seen. They were not F-86’s. They were three bright silver, delta wing craft with no tails and no pilot's canopies. The only thing that broke the sharply defined, clean upper surface of the triangular wing was a definite ridge that ran from the nose to the tail.

We have to stop here for a moment, and ask the relevant question: do these “UFOs” sound familiar at all?

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I dunno... maybe?

I don’t think any serious aficionado of military aircraft (which I don’t claim to be, by the way) could read this incident report and not think about our various existent stealth aircraft today, most notably the Northrop Grumman B-2 Spirit, otherwise known as the Stealth Bomber. It’s not the only aircraft to have been developed over the years which bears a remarkable similarity to the aircraft described in this early Blue Book era report, either. This general design which incorporates a tailless, delta-shaped aircraft with a “definite ridge” running from “nose to the tail” (the location of the cockpit, in essence) dates all the way back to hypothetical World War II-era designs produced by the Horton brothers.

To quote Bill Yenne again:

As with revelations about secrets within Area 51 that invited speculation about "what else is out there," the revealed advances in German aeronautics begged the same question. Among the myriad projects in wartime Germany was the Horten IX, a tailless flying wing created by the brothers Walter and Reimer Horten. This aircraft was built by Gothaer Waggonfabrik under the designation Go 229, and made its first powered flight in February 1945. Like most of the German experiments, the Horten aircraft was largely forgotten over time. That is, until 1988, when the US Air Force rolled out the B-2, which was a flying with no vertical tail surfaces. There was now a renewed interest in the "what else?" of wartime German secrets.

By all accounts, it sounds a lot like that “what else” might have been in our airspace well in advance of 1988, the year that the Stealth Bomber was finally given its first public showing.

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Kenneth Arnold displays a rather un-saucer-like artist's conception of one of his "saucers" that, again, reminds us of modern stealth aircraft.

To note these similarities between descriptions of a classic “good UFO” and known stealth technologies today is not to claim that all such reports of unusual things seen in U.S. airspace (or anywhere else) can be identified and explained. It's also noteworthy that there are some dissimilarities between the B-2 and some of the Blue Book era "deltas" that Ruppelt and others described.

However, in this instance, those similarities that do exist are almost too much to ignore… and in such cases, we must concede that the most likely solution is that, as Nathan Twining suggested, these objects probably were “of domestic origin,” and thus “the product of some high security project,” which obviously was not known to Headquarters Air Staff… not at that time, at least.

Micah Hanks

Micah Hanks is a writer, podcaster, and researcher whose interests cover a variety of subjects. His areas of focus include history, science, philosophy, current events, cultural studies, technology, unexplained phenomena, and ways the future of humankind may be influenced by science and innovation in the coming decades. In addition to writing, Micah hosts the Middle Theory and Gralien Report podcasts.

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