need FAST help for SCHOOL

[snakeye]

my project layed still for 2 months.. but I'm fully focussed on my "jet"again...

please read my last posts on

http://www.pulse-jets.com/phpbb2/viewto ... c&start=30

cause I got some questions but nobody answers me..

please help me guys

greetz Jimmy

[Rossco]

Righto, i havnt made a post here for a while, so this is my contribution to the site...this is a quick one tho,


Jimmy, there is a couple of things that you should take into consideration.

If this engine is not built exactly to plans (working plans, i assume its MK's plan?) It may not run without some tweeking/tuneing. Then, it may not run well. There is always the extreem case where it wont run at all!
I will assume that it is to plans of a runner for now.

Starting from the tail pipe is very difficult! It can only work sometimes, and with a lot of trial and error and knowledge of what your looking/listening for.
Throw this idea away for the moment. You can play big flames when you know what your after a bit more.

The fuel injection point is the next or most important thing.
First, it has to be a good pattern, as to mix in with the incoming air stream as best as possible.
Then there is positioning. THIS IS CRITICAL. Some engines will not run in any but one spot. Others dont care too much, although your fuel/thrust will be effected.
In this engine (of the top of my head) it would be a good place to start between halfway down the intake, to the start of the CC.


Righto, now you have an idea of what you need for them to run. A good design, and fueled right.

Starting that is the tricky bit before your used to it.

You look a little intimidated by your engine in the post! ha.
Get used to it, i think that it is only in howling mode (just burning in the tail pipe), it gets much worse/better when it really starts running.

You need to get an ignition point in the CC!
Thats where the bang to start the effect needs to take place.
A spark plug is really the way to go... look into it, its not that hard, with endless ways of doing it.

BUT

There is another way if you want to "play with fire".
This can cause a couple of burns if your not careful. Just keep an eye on which way the propane (gas/vapour... do not use liquid for this) is going before you light it. Your warned, and if you dont like the idea of lighting large amounts of flamible gas from your hand, dont do this!
Keep your propane tank right side up! Liquid propane can really let some heat out in a hurry!

Get hold of some auto brake line. Just steel tube, about 3/16-5/16 or 4 to 8 mm that you can cut with side cutters.
Then you make your injector. The Rosscojector as it so happens.
Cut one end of your fuel tube off with the side cutters. Force them right through, to leave a ver sharp edge to the now sqashed end.
You cant see it, but there is a very small slit in the centre of that edge, and it makes a hell of a flowjector.
Squeeze down, with the cutters on the points of this edge to open that slit, just so you can see it. This is the "tuning" of your injector mixture. The bigger the slit, the richer the mixture, and vica virca.

Hook it up to your fuel line, and very slowly increase your throttle (only just so you can hear it. Holding the injector in your hand for now, and pointing away from you!!!!!
Light er up with a cig lighter!
It can take some practice, and more tuening, but try to get a good long flame coming out of it, that is fairly lean (blue) but doesnt cut out to easily.
Now youve got the hang of it, feed it up the intake of your engine! EDIT:(you dont need forced air with this, thats the beauty of it)
Play with the mixture and how deep you hold it in the intake.
Be aware... doing this to an engine can instantly start it without warning. I have fallen over backwards before, and remember your still holding that flamethrower!

ENJOY...... CAREFULLY

Rossco

PS, i havnt re read this, so i might ammend it a little later... any comments, let me know.

EDIT: ooooooh, i forgot about the school mention.
They will not like this method! your going to have to get a spark plug in there, or... a sparkler can do the trick, tossed into the CC before you start fuel and air. You can use a fixed Rosscojector then, once youve found the right spot, mixture and throttle setting.

[hagent]

Spark plug
Spark plug
Spark plug
Spark plug
Spark plug
Spark plug
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Spark plug
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Spark plug
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Spark plug

Listen to Rossco it will save you hours of time.

I don't think you PJ was running either. I couldn't see any heat from the CC. Welding a nut onto your CC is very easy. Just insert a srew or old sparkplug into the nut before you weld - it protects the threads. This is the only reliable means of starting it especially infront of your teacher.

Good luck,

[snakeye]

so that rossco injector works without the sparkplug, I'm gonna try that first. if it doesn't I'm going to weld a sprak plug into my PJ.

And if I understood it right.. I don't need forced air ?.. thank YOU very much.

I'll let you know if it worked.

[Rossco]

No worries.
Its not really a generaly accepted way of doing it but hey, it works.
It does take some practice tho.
The only one that i cant seem to get going that way is a chinese??? dont know why.

It does limit the top end and running performance a little of your engine running with one of these. But for starting there great.

Assuming that you get the engine running really nice. Once youve this starting sorted, i suggest that for school, you hook up a permanent mounted Rosscojector in the optimum starting position. Then a separate running injector (in optimum running pos). Something like Erics optimum injectors, and a spark plug.

Crack the starting gas valve, hit the spark (could even be a piezio barby lighter) let it idle on the starter injector up to temp, then bring up to full power with the main.

Remember that a school is watching you like a hawk for safety conserns!
Holding a blower at the mouth of a fire spitting exploding missile/rocket desnt look good.
If you can get the starting down pat, this will be the most empressive way to get it going without allarming them.
Ofcoarse then you have to deal with the noise complaints!
Glad you enjoyed!

Rossco