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S.P.E.C.S the only true semi auto combustion's progress!

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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S.P.E.C.S the only true semi auto combustion's progress!

Unread postAuthor: thespeedycicada » Tue Nov 20, 2007 8:07 pm

This thread is for my new project S.P.E.C.S its not done yet and the proto wont be done for about a week or two and until tuesday next week i wont have a camera but i can update you all on it with words! as of now i have the camber and will prep it to be fitted for its valve tommorow i am currently etching a valve for testing the flex of the material i am using.I will most likely have test results up tonight.

Please put your comments/suggestions up so i can make adjustments changes and stuff.

for those of you who dont know S.P.E.C.S is a semiauto cannon roughly based on the dynajet principle.
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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 » Tue Nov 20, 2007 8:18 pm

Great to see that you are going ahead with this project cicada, what kind of rof are you expecting?
Best wishes with the build :wink:
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Unread postAuthor: thespeedycicada » Tue Nov 20, 2007 10:06 pm

The rof depends on how fast i can refuel it so im not sure yet i am sure that the reeds will open now though! its just one pice of knowledge closer to building this beast.
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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: mark.f » Wed Nov 21, 2007 7:46 am

So, is this going to be based of a pulsejet design or such?

My only question would be your dP/Dt of the chamber, (change in pressure). If you can come up with some sort of approximation of an equation relating pressure to time, you can derive dP/Dt from that, and solve for minimum pressure throughout the cycle, (solving for zeros of dP/Dt and plugging those into the original equation, and choosing test value to see if P is increasing or decreasing on the interval). This would be extremely important, as you need a pressure drop to around atmospheric pressure to make most feeding systems work reliably, (unless you are designing some type of new one).

Good luck with the design.
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Unread postAuthor: Tom » Wed Nov 21, 2007 9:06 am

A few projects back I made a 3-way valve, There are two tanks. The main and the charge, the third is to the chamber. When unpressed the main and charge tank are connected, when you "fire" the valve the charge tank is disconnected from the maintank and connected with the chamber. This valve worked great, only the fueling is a problem for a semi-automatic.
GR.Tom
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Unread postAuthor: psycix » Wed Nov 21, 2007 9:10 am

Semi auto is awesome, but how powerful will it be?
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Unread postAuthor: jimmy101 » Wed Nov 21, 2007 12:26 pm

S.P.E.C.S the only true semi auto combustion's progress!

This statement is incorrect. There have already been "true" semi-auto combustion spudguns. Revolver-X springs to mind.
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Unread postAuthor: thespeedycicada » Wed Nov 21, 2007 12:57 pm

Ohh yea i forgot about that but did revolver-x fire as fast as you could pull the trigger? As that is the goal of S.P.E.C.S i do realize that people have come up with combustions that had a mag and thus could be vented/fired quickly gorts blue flame is a great example of this.

After some testing the first prototype (there will be three) will need a valve with four petals to effectively evacuate the chamber.The large one however will either need six or two large double petal valves.
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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: thespeedycicada » Sat Nov 24, 2007 1:03 am

Really sorry about the double post but....

SPECS will be delayed a bit as i am ordering a few things for it.But in the meantime i think ill work on a triggered burst disc cannon to play with for a bit.Any way i have figured out that the reeds will open but they will need a short fat cc not a long one as the smaller barrel diameter should allow the vaccum to open up the reeds.You can see wit valved pulse jets that as the exaust pipe (barrel) gets wider and the diameter of the cc and barrel get closer together air for starting is required.
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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: TwitchTheAussie » Sat Nov 24, 2007 4:24 am

Use a clean burn fuel like propane and use a pressure gauge like on a hybrid. Quick fueling and shooting. Have fun n hurry up :lol:
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