Jims Little 3 Lb Thermojet

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Eric
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Post by Eric » Wed Oct 24, 2007 8:06 pm

The augmenter is way too small in diameter, it might be causing the flow to restrict out the back of the engine.

Try something about 3" ID, about 7" long, with a nice big flare on the front, maybe make a cone flare then hand hammer it with a ball peen hammer and a block of wood to get a nice flowing curve like an anular wing. Positioned maybe 2-2.5" behind the engine.

Should give you about 50-70% more thrust.

Eric
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metiz
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Post by metiz » Thu Oct 25, 2007 8:51 pm

Ah damn the guestimate did not turn out to well this time - worked fine with the intakes :P

I'll adjust it asap. Don't know if I understand you correctly tho
something like this picture? (obviously not to scale)
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Eric
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Post by Eric » Fri Oct 26, 2007 2:36 am

More or less that would work. About the best shape, as you can find in the nasa papers, would be something like in the pic I'm attaching.

The inside diameter would be about 3" for this engine, with a straight section and then a expanded tail. The tail shouldnt expand more than 5 degrees or so.

The better you make the flare the bigger the gain you will get.

Get a good thick block of wood or even a piece of firewood will work, and if you have a wood rasp or file shape the edge of the block so that you can lay the tube flat against it, and pound down against the wood. Whatever profile you file the wood down to will be the radius the metal will take when you pound on it.

Start by gently tapping and rotating the tube around to make sure it stays even as the metal stretches.

First start out by putting a bit of a flair on the straight section of tubing that is 3" ID.

This will start to curve the front out a little, then make a cone that matches that diameter, so say if you flared it out to 3.25" then start with a cone that goes from 3.25 to 4.5" or so.

Now weld that cone onto the augmenter, then go back to the wood block and hammer that until you get it curving nicely. Then depending on how far you can get it to curve you can weld a flat disc to that section, and pound that down so it curves back and makes a really nice flared intake.

Depending on how far you can flare out the main tube, you might only need to weld the one cone on, with a bit of practice and fairly thin metal you should be able to flare the 3" tube fairly far and still keep a nice curve on it.

If you make the flare on the front really well then the engine should get up to around 80% more thrust, making the engine easily much more fuel efficient than just about any small hobby turbine.

Eric
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metiz
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Post by metiz » Sat Oct 27, 2007 5:37 pm

Ok how´s this

(if this is not right either, just don't say it - i've been working on this thing for 6 hours and I realy don't want to pull it of again :P)
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Post by Irvine.J » Sat Oct 27, 2007 7:14 pm

Bingo mate, thats much better, nice job on the flare, you can buy large flange fittings ya know? LOL! Sorry you don't want to hear that I know!
Anyway, in a case like this, a simple cone to cone would be fine, but like eric said just have to make sure its a bigger D then the tailpipe itsel.

Oh yeah, did you get that wire?
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metiz
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Post by metiz » Sat Oct 27, 2007 9:08 pm

heya James

Thanks man and no, I REALY do not want to hear stuff like that :P
I have not yet bought the wire but I mailed an aditional 11 dutch suppliers and there are some prommising replies. One company who has it on the shelf asks 250 euro's for it EXCLUDING 19.5% taxes and nathional transport wich still makes it more expensive then importing the stuff from amerika including taxes AND 120$ shipping cost. Oh well, a couple other companies have replied already and I think I'll have some results pretty damn soon

btw the struts that hold up the augmenter on the pics are made of stainless and I have welded them with normal mellow steel flux core without problems, it adhere's fine. Get where I'm going with this? maybe as a plan b? what do you think.

Can you comment on this to, Berry? you seem to be a proffesional at welding seeing how you have welded up the lady Astor. And if this is a very bad idea, do you know where I might be able to get flux cored stainless steel wire in small rolls?
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Eric
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Post by Eric » Sun Oct 28, 2007 12:14 am

Thats perfect, should work well for ya and not restrict the exhaust flow.

I've never seen any nice factory made flares in any sizes that would be of any use for specific augmenters.

Eric
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metiz
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Post by metiz » Tue Oct 30, 2007 10:22 pm

The augmenter works. It's actually noticable when I put my hand in the jet stream.

Time to strap it to something
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paulj
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Post by paulj » Wed Dec 26, 2007 6:57 pm

Hi guys, thought i'd bump this thread back up as this is what i'm going to have ago at building, fortunatly i've got access to lots of equipment at my friends place.
see some of my jet related video clips here:-

http://www.youtube.com/profile?user=slartibartfast69

Jim Berquist
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Post by Jim Berquist » Thu Dec 27, 2007 1:46 am

Paul: I used a large soup can, rolled it from inside to out side like Erric is talking about. Just a ball pi en and block of wood. Clamped it to the tail end with a hose clamp. You can adjust it that way. The little Beast thing did at least 20% More ummmph! Total weight of augmenter, <2 oz. With the welding wire standoffs I used. I used a strait can and rolled the inside out somewhat like this . then dimpled the center to take it down to close to the diagram.

Not very scientific Eyyy!
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Re: Jims Little 3 Lb Thermojet

Post by Jim Berquist » Fri Jul 06, 2012 6:10 pm

I still have this engine and have messed with Injectors Eric put on it.

Pulled them out and Tryed a Pressurized Reuseable Paint Spryer.

Fires up Most Well if you have it set right.

A Rosco type injector works fine with Propane.


I used one like this but mine has two Ports on it.

One to Air Charge it and the other provides Liquid if up side down.
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Re: Jims Little 3 Lb Thermojet

Post by Mike Everman » Fri Jul 06, 2012 6:20 pm

Hi Jim, how you been?
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Re: Jims Little 3 Lb Thermojet

Post by Jim Berquist » Fri Jul 06, 2012 9:57 pm

All Quiet on the Western Front! LOL

Been Metal Detecting more then anything else.

Eric Seems MIA?

Not ansering on Skype or anything.
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