Pulser Jet?

Seen this interesting Spiegel article (plus photos) on a tidbit in Aviation Week & Space Technology. A quick search for an English text turned up this one.

After a long absence, what may be a classified aircraft powered by an impulse-type engine appears to be back in the air again. Its distinctive “donuts-on-a-rope” contrail was spotted recently above Utah’s Wasatch Mountains.

More than a decade ago, cotton-ball-like contrails were spotted and photographed periodically by observers throughout the U.S., but reports had dropped off sharply in recent years (AW&ST May 11, 1992, p. 62). The latest sighting over Utah on Mar. 21 was of particular interest, though, because the unknown “pulser” apparently was shadowed by another, conventionally powered chase aircraft that left a smooth, unbroken contrail. The two contrails–one smooth, the other a string of puffs–remained parallel across at least 120 deg. of sky, indicative of distinctly different powerplants.

The two contrails were spotted just before 3 p.m. MST by Phidias Cinaglia, a mechanical engineer who lives in the mountains east of Salt Lake City. He did not see or hear the two aircraft fly overhead. However, he noticed the contrails very soon thereafter, because they were still well defined. Initially, he saw distinct side-by-side puffs, suggesting a twin-engine aircraft with powerplants firing simultaneously. Cinaglia remarked that each of the impulse contrails was “an unbroken string of pearls” across a large arc of the sky.

interesting, I wasn’t aware there were any pulse jet powered aircraft. A pulse jet is in theory more efficient than a standard turbojet but they are hot, noisy, and hard on parts so I wasn’t aware anyone had made an actual aircraft wtih a pulsejet.

For anyone interested in pulse jets, check this out:


Well the whole point of the stories and the idea behind it was that no one knew there was such a thing, yet someone photographed this odd contrail more than ten years ago (one videotape IIRC from the cabin of a passenger liner), an AW&ST guy showed it around (or maybe Glenn Douglas did) and an engineer or somesuch said, and I paraphrased, “Well I’ll be damned, they actually did it - that’s what we think a contrail of a pulse jet would look like.”

I get AW&ST and will look for a mention if it’s in a new issue, unless they’re just referring to the article they published a long while back.

— Alan

Looking at the new photos, the problem is that the “donuts on a string” described in the 1990s looked simply like that - these however just look like donuts. You can’t see the string at all - which may have faded or whatever, but the other contrail is plainly visible so…

— Alan