does any one ever check this site valveless pulsejet engine

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nanotech1a
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does any one ever check this site valveless pulsejet engine

Post by nanotech1a » Fri Nov 27, 2009 2:15 am

has anyone ever bought any plans from them just want to know if this one was build by some here in this forum or is it a waste of money

http://www.alternative-technologies.org ... ngine.html

the other engine they have look at the bottom of the page

http://www.alternative-technologies.org/aircraft.html

any comments appreciated

steve normandin

tufty
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Re: does any one ever check this site valveless pulsejet engine

Post by tufty » Fri Nov 27, 2009 7:52 am

nanotech1a wrote:has anyone ever bought any plans from them just want to know if this one was build by some here in this forum or is it a waste of money

http://www.alternative-technologies.org ... ngine.html
Hi Steve.

Ignoring the fact they pissmell "valveless" on the page header, I'd suggest it's probably not a go-er. Looks a bit Foa-ish, the annular concept is particularly hard to make work. Also, there's no user comments, no videos, no user build photos, nothing. Also, as Eric commented the last time this one came up :
Eric wrote:I'd be kind of skeptical buying plans from a place that also sells ebooks on werewolves, mind control, and also has sponsored links to porn sites...
If you want to build a valveless, I'd strongly recommend going for one of the free plans available from here (especially, if you're looking for something weldless, the "pipewood"). Not only do you have a set of plans that *will* go if you follow the instructions, but you have a community that are willing and able to help you if it doesn't.

Simon

nanotech1a
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Re: does any one ever check this site valveless pulsejet engine

Post by nanotech1a » Fri Nov 27, 2009 12:16 pm

i am not trying to push there product but i would like to if someone here actually bought the plans and made an engine out of it for evaluating its performance
what is real intringing about this one is the coaxial tailpipe design witch is realy interesting

steve

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Re: does any one ever check this site valveless pulsejet engine

Post by Ghrey » Thu Dec 10, 2009 9:47 am

Coaxial designs LOOK great on paper. I know I like them.

Execution, so far, has proven extremely problematic.

Eric posted a really good synopsis somewhere on this forum. ( if memory serves )

I can only add;

All of your diameters change with heat, and the Coaxial/Annular design just magnifies this effect. Also the upstream end of the tailpipe ( exhaust ) is subjected to incredible heat, slag is a common result.

I am still working on one, but, I suspect it will only prove that it is a bad idea.

Search the boards under "Coaxial" and "Annular" Annular should give more results...

Cheers.
In the process of moving, from the glorified phone booth we had to the house we have.

No real time to work on jets, more space, no time.

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Mark
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Re: does any one ever check this site valveless pulsejet engine

Post by Mark » Thu Dec 10, 2009 1:24 pm

To me, it seems like the challenge with sleeved valveless engines is that the gases aren't confined to a coherent flow. I picture air charging in and out at uneven rates around the skirt where pressure inconsistencies can arise around the circumference, dampening feedback. Also there is more surface area/drag over a typical straight cylindrical port.
If you could pancake out the sleeved intake into a flat profile, one might see one sheet of metal above the other like a large rectangle of sorts.
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Re: does any one ever check this site valveless pulsejet engine

Post by Ghrey » Fri Dec 11, 2009 6:55 am

ANY imperfection is amplified. The results are much as you state. Flow can Ideally travel along the outer walls to converge at the head of the CC for efficient combustion, but that model discounts much of the dynamics of pulsating combustion, but still may function on pulses, it self.
The model gets middy fast.

I am not quite clear on your approach, a rough illustration would be helpful.

Some such devices of this type have in fact functioned quite well, BUT no one really can quantify why or give a definitive design model.

I am attempting to decouple the intake entirely from the system so that the engine has more the dynamics of a jam jar.
And yes I do suspect that this is a fools errand. I hope that I may learn from it.


Cheers
In the process of moving, from the glorified phone booth we had to the house we have.

No real time to work on jets, more space, no time.

Life still complicated.

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