Please put your "I am new and need help" question here.

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Flyman
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Re: Silly idea

Post by Flyman » Sun Jun 26, 2011 5:29 pm

Never thought about using a bathroom scale! I just tried it, and it read about 3 lbs, so judging from that it's barely enough. Could you possibly tell me how much thrust the "Lady Jane Grey" has? - since it seems more powerful from video presentations.

Thank you

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Re: Please put your "I am new and need help" question here.

Post by Mike Everman » Mon Jun 27, 2011 7:32 pm

No idea. Check Larry Cottrill's threads on that motor to see.
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pulsepower
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Re: Please put your "I am new and need help" question here.

Post by pulsepower » Tue Jun 28, 2011 7:17 pm

Hey guys,
My name's Marvin and I'm from Düsseldorf (germany). I 've designed my own pulsejet in a scale of approx. 3,4 from plans I got at this site:
http://home.no/andreas.sunnhordvik/Engl ... less_e.htm

For the cumbustion chamber I used an old CO2 one-way bottle I'd cut in the right lengh.
The pipes I used are trash from old bicycles or things like that made of normal steel.
But somehow it refuses to work. For firing it up I use a propane/butane mix and a pressure around 2 Bar.
However,it refuses to work.I tried firing it up by using a sparkplug (nothing happened) and using sparklers (at least it produced single explosions.)

here's a pic of it (I know its a bit blurry :oops: )
Greetings:
Marvin
Attachments
DSC00886.JPG

Kool
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Re: Please put your "I am new and need help" question here.

Post by Kool » Wed Jun 29, 2011 8:49 am

In fact, pulsejet could not simply scaled down by a factor, but it could gonna work :wink:

A few suggestions:
- Are you sure the engine is totally leak-free?
- The intake must be flared.That means that the last 20-30mm of the intake tube should be angled outwards so as to make the opening wider than the tube.
- You need a leafblower/ kompressor to blow in the inlet.
- How are youre injecting the fuel? A good solution that worked for me was as in the attachment.
- The last section of the exhaust looks too smal for me. I'm not very sure, but it should minimal have the profile of the inlet

Good luck with it
Attachments
injector.jpg
Injector, holes to side of combustion chamber
injector.jpg (8.68 KiB) Viewed 3306 times
...It's better to generate heat efficiently, than recover it efficiently...

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Re: Please put your "I am new and need help" question here.

Post by ganuganu » Wed Jun 29, 2011 8:57 am

here take a look at the pdf file for the injector design..And i think your exhaust pipe dia is small,try to make a larger one..And as kool said flare your intake..
Attachments
lh55lbsfuel.pdf
(18.53 KiB) Downloaded 179 times

pulsepower
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Re: Please put your "I am new and need help" question here.

Post by pulsepower » Wed Jun 29, 2011 10:03 am

Thanks for answering! My fuel injector is just a small aluminium pipe,which ends approx. 3mm in the chamber.I've already tried to make a conus or extend the intake,but it always ended up in a mess :cry: . how do you produce those things?

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Re: Please put your "I am new and need help" question here.

Post by ganuganu » Wed Jun 29, 2011 12:22 pm

pulsepower wrote:Thanks for answering! My fuel injector is just a small aluminium pipe,which ends approx. 3mm in the chamber.I've already tried to make a conus or extend the intake,but it always ended up in a mess :cry: . how do you produce those things?
use this to calculate cone dimensions..it will be really helpful..
Attachments
pjc14.xls
(361 KiB) Downloaded 197 times

pulsepower
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Re: Please put your "I am new and need help" question here.

Post by pulsepower » Wed Jun 29, 2011 1:40 pm

thanks a lot!! great stuff!
"flaring the intake" means making a cone or an augumentor?
sorry for asking this but my scientific english knowledge is not very good.
Greetings:
Marvin

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Re: Please put your "I am new and need help" question here.

Post by ganuganu » Wed Jun 29, 2011 2:25 pm

pulsepower wrote:thanks a lot!! great stuff!
"flaring the intake" means making a cone or an augumentor?
sorry for asking this but my scientific english knowledge is not very good.
Greetings:
Marvin
no,augmenter and cones are different from flaring..just take a look at the picture..
The .xls file which i gave in previous post was to make cones and augs for your pulsejet engine..

suggestion: if you are making pulsejet for first time please make the engine which was already done and tested by someone,then you can design your own engine..lockwood is not recommended for beginners..
Attachments
FLARE.jpg

pulsepower
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Re: Please put your "I am new and need help" question here.

Post by pulsepower » Wed Jun 29, 2011 4:26 pm

Thnk you for that drawing,ganuganu i welded a conus at the intake,before you wrote your tips...
And I welded a pipe with a conus aon the exhaust,but it still refuses to work :(
it always the same: If i'm just blowing air in, there's only a flame,if i take it away there's one combustion or maybe 2.
I've tried it with diffrent amounts of gas without the wished result.Here's a pic of it,too.
Do you think I could just make a horizontal exhaust like on the valved ones and it'll work?
Attachments
DSC00888.JPG
DSC00887.JPG

Mike Everman
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Re: Please put your "I am new and need help" question here.

Post by Mike Everman » Wed Jun 29, 2011 5:14 pm

That cone you've put on the intake has probably doubled the (acoustic) length of the intake. I suggest you cut that cone off again and hammer a flare on it to about 1.25D
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pulsepower
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Re: Please put your "I am new and need help" question here.

Post by pulsepower » Wed Jun 29, 2011 7:23 pm

The cone is cut off again, And I tried to flare the intake but the resulting Intake looks like somebody shit it out :(
Do you think that is enough?
Attachments
DSC00890.JPG

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Re: Please put your "I am new and need help" question here.

Post by Mike Everman » Wed Jun 29, 2011 7:34 pm

Not pretty, but looks OK. Where are you putting your fuel in?
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pulsepower
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Re: Please put your "I am new and need help" question here.

Post by pulsepower » Wed Jun 29, 2011 7:59 pm

on the first pictures i've posted you can see the sparkplug and a thin aluminium pipe.That's where i inject the propane. But I'm wondering why the pj doesn't even ignites when I'm using the sparkplug,and there's defenetely a spark created by a piezo igniter.

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Re: Please put your "I am new and need help" question here.

Post by Mike Everman » Wed Jun 29, 2011 9:26 pm

Aluminum will melt once you get going. more importantly, the placement may not work there. I would take that out for now, and make a simple "stinger" injector so you can move it to different places in the intake (use 5-7mm copper; at the tip, cut it with wire cutters at a 30degree angle. this is called a "rosscojector". You can search for this in the tools and construction forum). fuel injection will best be at the flare of the intake to a point down inside it somewhere.

Your piezo, is it a manual "clicker"? If so, this is making life very difficult. If you can get a battery operated one, or use an AC one from a clothes dryer.
1. Always open up the sparkplug gap big or just break the electrode off.
2. Clamp the motor in a vise
3. Have a spark that you can leave ON until it starts
4. Use the fuel stinger and starting air, but you may get results with just the stinger and no air (just maybe...) the point is to find where the fuel should go in on this motor.
5. Use small amounts of fuel and air to start
Mike
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