www.pulse-jets.com

I cant see why valve travel in an opposing direction will contribute to fatigue provided that the valve is not stressed past its elastic limit. I agree that material and shape will always play an important part in extending valve life, but perhaps offseting the valves from the seats might contribut...

Viv - This is what I meant to do. I doubt that it will improve on your observation about turbulence, but at least it will carve out a clear difference between the momentum of the gas going straight out forward and that snaking its way through the recycling tube. The higher molecular momentum wins! L...

Larry I cant see a pressure differance across the deflector ring to cause a mass flow? I can see the anular gap choking like a `Delavel nozzle (good) but the extra internal deflector ring wont have any appriciable flow altering effects Viv Viv - Nuts! I forgot to 'bucket' the inner ring. I'll get t...

Viv -

Ok, here's a mod I came up with as a real Tesla valve test version.

L Cottrill

Viv - Yes, of course, I am aware of the resemblance to the Foa engine, which is one of the nicest valveless front ends ever proposed ... and certainly, mine is not simpler to do. Not for the squeamish -- a real Troy Legner project. I should have acknowledged the Foa heritage. However, this does try ...

YAVPJFE [Yet Another Valveless PulseJet Front End] -

This time it's an amphora [or maybe just a streamlined cuspidor] surrounded by a single-stage Tesla valve, both of which serve to capture otherwise lost momentum from forward-firing gases.

What do you think?

L Cottrill

Mathias - Another thing that can affect good starting and running is the centering of the reeds over the holes. MAKE SURE your reeds are EXACTLY centered on the holes. Also, make sure that they lie perfectly flat against the valve plate surface. The valve plate MUST be flat, smooth and clean for goo...

Gentlemen - There is another approach, taken in the venerable Dynajet, that works well, at least in fairly small size valves: I believe that the retainer is NOT designed to take the reed hitting 'all at once', but rather that the valves 'roll out' onto the retainer without kinking, and with the bend...

Mark - I also think you could do something like this, not with a true howler tube, but with a simple 'jam jar' type device like John's, but with one addition: a Logan-style tube with external fuel supply and 'choke plate' at the outside end. Imagine John's device [but with the stack solidly attached...

Larry, I was wondering if a cup type design like you find in a wind speed gizmo would work. It would harness the thrust head on. I think your concept would be interesting to have the pitch angle to the thrust variable. I'm thinking that maybe the dynamics and effeciency might be effected when a bla...

John - This is very impressive! So - there IS a stack involved in getting pulsation. The reason the stack makes a difference must be what Hank alluded to in his article: increased velocity [as evidenced by the 'buzzing' sound it makes, which is from the rapid 'pops' of ejected gas]. It's extremely i...

John, with a 1.125-inch throat, that puppy must put up a pretty good roar. It's a nice design, with lateral breathing holes, like Hank showed in his article in the last issue of JetZILLA. What's the length [bottom of the whole thing to top of the cone]? Is it really just 'chrome' as the ad says, or ...

Don - I fully agree that the velocity is indeed the problem. Your test setup for the experiment sounds fine, with just one exception: You're not getting a real bang from the driving explosion. Note that we expect good bangs from pulsejet combustion, even from a nicely-running jam jar; I think the co...

Don - Well, that agrees with the trial firings of the original Synchrodyne prototype. My belief is that this failure is caused by making the throat too narrow, so that the forward flow is essentially choked. Of course, there could be a more basic problem that is not being understood, at least by me ...

As I said in the first posting, for this thing to begin to hope to work, the bucket should be much bigger in proportion. It will have to be big enough to take in all the hot gas that is spewed out in the front, or else the excess of hot gas will stream out of the intake and exert thrust against the...