New guy getting started

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CLAY
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New guy getting started

Post by CLAY » Wed Dec 03, 2008 5:57 pm

Howdy! I'm a physics teacher in Michigan, USA. I have been studying pulse jets for quite some time- especially for my physics class when we study engines. Last year at this time I almost bought one- this year I have decided to build one. I'm a fairly handy fabricator with a welder and metal shaping capabilities- the plans I have downloaded (so far following Larry Cottril's Elektra I) have been pretty straight forward; however, I have a questions on fueling and starting.

I printed off the schematics for a starter- using a flasher unit. That seems pretty straightforward. I also am a motorcyclist and have many parts for my older bikes (Yamaha XS650's) incluing coils and condensers to create the spark.

What are you all using for fueling? Propane seems the fuel of choice- I have a spare tank- my question involves the regulator. What type of regulators are you using and where did you get them? Thanks!

I have been doing lots of research and reading both here and other places, and I am very excited to give an engine a try. I tend to be a tinkerer/inventor by nature, so the DIY factor here is huge. I forsee a small gocart powered by pulsejet in the future if I continue to find this as enjoyable as I have so far. TIA.
CLAY
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Mike Everman
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Re: New guy getting started

Post by Mike Everman » Wed Dec 03, 2008 6:04 pm

Welcome, Clay.
Check viewtopic.php?f=3&t=4950

In short, your plan will include how to do the injector, and you should know that you will not want a regulator on your (preferably) BBQ tank. You'll want all the pressure it can give you.
Mike
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Re: New guy getting started

Post by larry cottrill » Wed Dec 03, 2008 6:42 pm

Clay -

Yes, welcome aboard! For an Elektra I, you should use the final dimensions of the running prototype as shown in the attached drawing. The starting air tube is optional, but I think it works well and makes things easier (if you have a small compressor handy, equipped with one of the little hand-held "blowgun" attachments). The starting air tube, if used, should be aimed right down the center of the intake pipe. Your fuel pipe can be 1/8- or 3/16-inch copper tubing, with the spouting end located about where the intake penetrates the chamber corner, or even a bit farther in. You don't need to do anything special with the spouting end of the fuel tube at all, i.e. just a clean cutoff end will do nicely.

You might be confused by my comments on using a regulator (I always use my regulator to fuel small pulsejets!), but you are well advised to not bother with it, since controlling the whole fuel flow process from a valve at the tank is simple and works well. You should, however, equip your tank with a 90-degree "ball valve" approved for gas. The reason for this is that you want a "quick shutoff" valve for safety, not something you can only shut off by turning it repeatedly over a many-seconds interval. It takes a little practice throttling with such a valve, but you can learn to do it, and it's easier if the valve handle is lengthened for greater leverage.

Good luck with her! If this works well for you, you should then try an Elektra II -- it's at least twice as good an engine, better looking and probably easier starting and more throttleable. It's more work, but the materials are basically exactly the same, so the cost is approximately the same, too.

L Cottrill
Attachments
Elektra_I_prototype_dims_rev01.png
Elektra I prototype final "as built" dimensions. Drawing Copyright 2006 Larry Cottrill

CLAY
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Re: New guy getting started

Post by CLAY » Wed Dec 03, 2008 7:08 pm

Ahh! Already I feel like an idiot! :o

It's not the Electra I I have been looking at building, it's the "Short Lady"!

Larry, might I say your pages have been an incredible resource. I have spent many hours reading over your information. Thank you!
CLAY
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Re: New guy getting started

Post by larry cottrill » Wed Dec 03, 2008 7:17 pm

Clay -

All right -- much better! However, you can do even better with Eric Beck's improved version, the 'Advanced FWE', unless you just really want to build the classic FWE prototype with the intake protruding down into the chamber. Eric's engine is just as easy to build, slightly more compact, and better performing. If you build it in mild steel, you can still use the antenna mast tubing tailpipe I used on the original instead of rolling your own. That would make it a very nice and easy build.

L Cottrill

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Re: New guy getting started

Post by CLAY » Wed Dec 03, 2008 7:19 pm

Mike Everman wrote:Welcome, Clay.
Check viewtopic.php?f=3&t=4950

In short, your plan will include how to do the injector, and you should know that you will not want a regulator on your (preferably) BBQ tank. You'll want all the pressure it can give you.
Got it- then I just need the fitting and the hose, right? I'll probably set up the fitting to run through a SS supply line then into the copper fule line like others have done. WHat size copper fuel line are you running on the short lady? Also, are you pinching the end like I have seen to increase the mixing?

Larry, where will I find plans for the FWE?
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Re: New guy getting started

Post by larry cottrill » Wed Dec 03, 2008 7:44 pm

Clay -

I just used 1/8-inch copper line for the actual "stinger" into the intake, with nothing at all done to the end except to make sure it was a very clean cut end without little burrs, etc. Of course, experimenting with fueling is one of the enjoyable things to do after you learn to reliably start and run your engine. These engines take just a breath of starting air, incidentally -- beginners usually start out by overwhelming their engines with air and then wonder why "it just won't sustain". If you use a blower, you can just "tease" the intake with the air while you gradually increase fuel flow until it "catches".

The spouting end of the stinger can be just inside the intake flare (inefficient) or about 3/4 of the way in toward the point where the pipe enters the chamber. It does not take very fast fuel flow to get the mixing required to get startup, and after that the engine is reasonably throttleable. Even more so with Eric's redesign. I think you can still get the Advanced FWE plans as a free download from Eric's site:
http://www.Beck-Technologies.com

L Cottrill

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Re: New guy getting started

Post by CLAY » Wed Dec 03, 2008 8:11 pm

I didn't see the plans, but I emailed Eric to see if he had them somewhere. Work should begin on the project tomorrow night I think. I'm excited to begin!
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Re: New guy getting started

Post by Mike Everman » Wed Dec 03, 2008 8:23 pm

Since you're in a hurry, here it is from my archives.
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advancedfwe_159.pdf
(443.42 KiB) Downloaded 141 times
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CLAY
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Re: New guy getting started

Post by CLAY » Wed Dec 03, 2008 9:55 pm

Thanks a bunch- I'll probably grab some metal tonight or tomorrow on the way home. Time to begin fabrication. Thanks for all your help! I'll post pics and such as the process goes on.
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Ghrey
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Re: New guy getting started

Post by Ghrey » Thu Dec 04, 2008 7:19 am

Just a brief note on regulators;


If you do find that you need one for some PJ project, use a roofing torch regulator, they are high flow and durable, low cost is also a plus.

.:.
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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Re: New guy getting started

Post by CLAY » Thu Dec 04, 2008 2:58 pm

Ghrey wrote:Just a brief note on regulators;


If you do find that you need one for some PJ project, use a roofing torch regulator, they are high flow and durable, low cost is also a plus.

.:.
Where does one find such a beast?
CLAY
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larry cottrill
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Re: New guy getting started

Post by larry cottrill » Thu Dec 04, 2008 4:01 pm

Clay -

For your testing, the regulator really is unnecessary. But, since this is a somewhat "controversial" topic, I will briefly state why I use one.

Most directly, the regulator gives you constant pressure over time applied to the input side of your throttle valve. This means that for long runs, you can "set it and forget it" instead of tweaking it every so often to keep things running right. I once had to run the Short Lady for over half an hour, for the famous Wired magazine photo shoot. With her running through the regulator, I never had to worry about her quitting as the propane tank got cooler and cooler (which it did!), so we could just concentrate on messing with lighting, poses, etc. For test runs of a couple of minutes, this doesn't matter if you're using a good size tank of propane, like the 20 lb BBQ cylinders. Little regulators for regular size BBQ grilles are utterly hopeless.

What has been said already about them is exactly right: You MUST have a BIG (meaning, high flow volume) regulator, even for small engines like the "standard" FWE styles. You don't want the regulator to be just another silly flow restriction in the path. The one I use looks exactly like a small welding outfit regulator, but it's actually MUCH different -- its total output range is only 0-25 PSIG, but the whole body and the pad and seat are ported for very high flow. It's the highest flow air regulator Victor made back in the 1970s, procured by special order. Its input side is limited to 500 PSIG, much too low for use on an oxygen cylinder, for example.

Anyway, for ordinary testing, you can consider it a "nicety" and you really can do without it.

L Cottrill
Attachments
Good_propane_regulator_setup_crop1.jpg
Victor regulator set up for propane, as originally rigged with right-angle needle
valve. I now use a 90-degree swing ball valve for throttling and quick shutoff.
Photo Copyright 2004 Larry Cottrill

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Re: New guy getting started

Post by CLAY » Thu Dec 04, 2008 7:46 pm

Cool- that's what I figured, but I thought if there were a cheap source nearby I'd give one a go.

Well, I have all my metal, thanks to an electrician buddy with a bunch of various sized metal conduit in various lengths, and I have the sheet left over from other projects. Tonight it will be time to turn on the heat in the garage and do some fabrication. I can hardly wait to get home. Some of the finer metal work intrigues me, such as heating and hammering the bells. I look forward to the learning curve. When my buddy dropped off the stuff he laughed and simply said "I want to see it run!", which he surely will.

Good stuff!
CLAY
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Re: New guy getting started

Post by CLAY » Fri Dec 05, 2008 1:16 am

First off, I have the pipe ends flared using heat and hammering. I can see if I keep this up a real anvil would be handy. I find it incredibly rewarding to sculpt metal with heat and a hammer! In an hour or so after the kids are in bed I'll head out and begin work on the combustion chamber.

OK- here's a question:
A buddy of mine, a master fabrictor with stainless (it's his business *and* hobby) wants to build a big lockwood for demonstration and to "toy" with. Understand Derek (my buddy) owns a loader and a skytrack for fun. He's into big things- and being single and a good money manager, he can handle it. Anyway, are there plans for a 50-100lb thrust lockwood out there? The Lockwoods seem to be more effecient and develop more thrust, don't they?

Or could one simply scale up the Short Lady design? I didn't think you could really simply scale up a design, since resonance plays a role and I can't imagine that ratio to size is simply linear.

I have been searching here for about 20 minutes with no large lockwood plan results. Any ideas? Thanks!
CLAY
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