Bumbling around the internet this afternoon, I found this link to a Mechanix Illustrated contest to design and build a jet engine. Lots of good ideas in this scanned article to get started on the competition.
Hey Gunner! Ever make model ramjets out of .50 cal brass?
As a kid in the 60's I was really into model airplanes, and had a couple of jets.
Dyna and OS Max (if it means anything to anybody) pulse jets, and to this day think they're responsible for my partial hearing loss... jeez were they loud, and low frequency loud too. About 440Hz IIRC. I remember they could literally be heard for miles, and gave my dad nose bleeds.
They liked to go through reed valves... chunks would break off around the edges of the 'petals', and they'd chew up the aluminum valve seats in short order.
I think some people still mess with them, engines still show up on eBay from time to time... a few Dyna Jet's are there now as a matter of fact.
Erik
No! And that sounds neat as hell! Got some info?
Gunner
That rifle hanging on the wall of the working-class flat or labourer's cottage is the symbol of democracy. It is our job to see that it stays there. - George Orwell
Well I was only an onlooker, not a constructor, and it was 50 years ago, but if I remember right it went like this:
The armorers (it was usually the armorers) would punch the primer out of the end of a spent .50 cal casing. Then they would drill two holes into the side about a half inch from the end. One hole was for a model aeroplane glow-plug, the other a little spigot thingy that had a tapered needle valve, I think it was from a model aeroplane engine too. They would saw the neck off the end of the case so a penny could be dropped inside, and this was pinned in place down at the end of the case by a piece of twisted monel aircraft locking wire. The penny was trapped over the primer hole, but not tightly, it was free to rattle back and fourth maybe 50 thou.
Then the casing was mounted in a vise and fed JP4 through a length of tubing. The armorer's guncart that was used to prime the Wurlitzer gun chargers was brought into play to blow a good blast of compressed air into the end of this diabolical device. A quick check to make sure the flight sergeant was somewhere else and a battery was hooked up to the glow plug.
The first result was a lot of flame and smoke and fiddling with the fuel adjustment, but if you got it right the flame would disappear inside the case with a pop and drive the penny closed against the primer opening. The air blast would promptly open it again, then the exploding air-fuel mix would close it. The rig was essentially a stationary pulse-jet of the same basic operating principle as the engine that drove the German V1 "buzz bombs".
I don't think I ever saw one run more than a minute before the casing melted though!
Nah, nobody would mess with (
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I was gonna say, where's Bruce to liven up this thread? ;)
BTW, how are things going these days?
Tim
-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @
O the memories of Dyna Jets
Hit 212 MPH with one in a SideWinder C/L plane in the late 50's early 60's.
Still have them, need to get one out and fire it up just to renew the memories.
Hugh
Don't ask :-)
Things are actually pretty crappy since the government stepped in to shut down my activities -- of course it didn't help that I'd embarrassed them by publicizing the fact that they okayed me to export advanced jet engine technology to Iran in direct contravention of treaties that prohibit such things.
No, I had no intention of exporting the technology but I thought I'd ask -- just for the hell of it and was absolutely gobsmacked when they said "yes, there's no problem with that, you can go ahead"
That little fiasco and what appears to be a lot of nudging from the US administration resulted in some rather nasty retaliation that has left me high-and-dry.
One of NZ's leading news and current affairs programs did a piece on my situation and it can be seen (Windows Streaming media) at
C'est la vie I guess.
-- you can contact me via
The Man has zero sense of humor. Mess with the Man, and he'll surely mess with you.
Gary
Whatever happened to the great US freedom of speech and the right to bear arms? (although I suspect that doesn't include missiles :-)
The silly thing is that I had contacted the FBI and DARPA before I started the project and asked them for their comments. The FBI sent me an automated acknowledgement of my communication, DARPA ignored me.
I even offered to share all my work and results with DARPA because they're charged with developing a defense against low-cost cruise missiles and have a programme in place to do this.
It's a bit harsh therefore, to turn around later and slam someone who has done their best to inform and seek comment.
What's more, the whole rationale for the project was to make it
*harder* for potential terrorists to build such a device by arming the public with the knowledge of what such a nefarious group would need and how they would likey go about the task.I have never (and never intended) to publish any information that wasn't already available elsewhere in the public domain or on the net.
Indeed, if you know where to look you can find sufficient in the way of drawings, plans, pictures and other technical details to build your own V1. Hell, the US government's own public NACA archives (available online) contain a *very* detailed technical description and analysis of the Argus pulsejet engine used on the V1.
The real reason they got snotty was probably because I publicized a weakness in their defense capability that they really didn't want the public to know about (although you can bet that terror groups have known about it for a long time because, once again, it's well documented on US government websites).
Ah well, that's politicians for you :-(
-- you can contact me via
Doesn't apply outside the US.
Yeah, but you drew all that information together in one place, and showed how it could be made to work together, inexpensively. That's 99% of any engineering design project. It may have seemed an obvious synthesis to
*you*, but to the non-engineer it is an astonishing cookbook. Even to another aeronautical engineer, consulting the information you correlated represents a tremendous saving of time, effort, and money.You might want to consider the fate of Gerald Bull. If the Man considers you a continuing irritation, assassination isn't out of the question.
Gary
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