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Dynajet spudgun?

A place to ask general spud cannon related questions.
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should this be attempted?

yes!
6
60%
hmmm the theory is good but some things should be added/changed
2
20%
i have no clue what you mean!
2
20%
 
Total votes : 10
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Unread postAuthor: MaxuS » Fri Nov 30, 2007 5:21 pm

It would be worrying for me it my spudgun actually glowed brightly with heat, so how hot does it get?
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Unread postAuthor: Tom » Sat Dec 01, 2007 10:23 am

I have seen them to, there is even a website how to buildt one(valveless pulsejet go-kart). But in my opinion they are too big, with a jet engine you would catch less air resistance
GR.Tom
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Really really proud member of the Dutch Spud Clan!

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Unread postAuthor: octane89 » Sat Dec 01, 2007 12:54 pm

Id say draw up some ideas, post them here, see what people say, and do as you please. You seem to know about PJ's enough to trust yourself with this so give it a try with some sketches.
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Unread postAuthor: jimmy101 » Sat Dec 01, 2007 3:30 pm

I think it would be pretty tricky to get this to work.

Most valveless pulsejets (and, i assume, valved jets) cycle at a couple hundred times per second. Obviosly that is way too fast, for no other reason than it'll get too hot.

If you slow the ROF down to say one shot per second then you really don't have a "jet". Simply an auto cannon, one that refills with fresh air automatically.

You might be able to get the reed valves to work to automatically let fresh air into the chamber but the reeds will have to be substantially stronger than what is used in a reed valve jet. The jet operates at fairly low pressure, perhaps only a couple PSI above ambient. A spudgun is going to be hitting peak pressures of at least 50 PSIG. I would think the typical reed valves used in a jet would be trashed the first time there was a round in the barrel and the pressure rose high enough to actually launch the round.
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Unread postAuthor: thespeedycicada » Thu Dec 13, 2007 11:05 pm

No the valve will not be trashed they are made of steel that is thicker than soda cans and soda can burst discs blow at a higher temperature than a combustion will create.
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current projects: co-axial piston valve.Status DONE!
S.P.E.C.S update mk 1 construction begining in febuary all the maths for it are done plans are drawn up and parts are listed.
NEXT project:auto piston valve.
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Unread postAuthor: Novacastrian » Fri Dec 14, 2007 1:28 am

thespeedycicada wrote:No i have not used my jets in planes and probaly never will as these planes can reach 200+ mph! Besides my jets are valveless like the one below.The dynajet produces around 4 lbs of thrust and is about 1 lb or less in weight.I most likely will start this project tommorow but morre comments/suggestions will be appreciated the prototype will be pvc to test the theory.I also encourage some of you guys to get into pulse jetting its reallly addicting seeing a heavy tube get red hot in 15 seconds with enough noise to blow your eardrums.Ahhh the two of the most dangerous hobbies ever,spudding and pulsejetting.


Sounds like just the thing i need to piss off my neighbours :twisted:
Not illegal and "Perfectly" safe!
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When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

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