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New fuel/air injection method?

Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
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Unread postAuthor: POLAND_SPUD » Sun Sep 26, 2010 10:43 pm

the air through meter design

Ohh I think I get it now... I just had one of those 'aha' moments :wink:

The meter tube has smaller volume than the volume of the chamber so you don't need to set the reg to 6.44psi but instead you can set it to ~64.5 psi (provided that the meter V is 1/10 of the chamber volume).

'Air through' means that air flows to the chamber via the meter - thus mixing it.
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Unread postAuthor: Technician1002 » Sun Sep 26, 2010 11:13 pm

D_Hall wrote: I've done metering with two similar sized orifaces running different pressures to deliver the correct fuel/oxygen mixture. Very easy to do.

Admittedly, in my system it was for an ambient pressure system so that made things easier but it's still a thought.


The idea behind the same pressure and two orifice sizes is it can be used for various delivery pressure while maintaining the same ratio, such as filling a 2 to 8X mix hybrid. It would even properly fill a vacuum purged chamber.
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Unread postAuthor: SpudBlaster15 » Sun Sep 26, 2010 11:28 pm

POLAND_SPUD wrote:The meter tube has smaller volume than the volume of the chamber so you don't need to set the reg to 6.44psi but instead you can set it to ~64.5 psi (provided that the meter V is 1/10 of the chamber volume).


Essentially, though I never design the meter volume to be any specific fraction of the chamber. That ratio is worked out after the design is assembled and precise fluid volume measurements are taken.

'Air through' means that air flows to the chamber via the meter - thus mixing it.


Yes, mixing was one of the primary motivating factors behind the design. Earlier volumetric metering systems had issues with air/fuel mixing, and were extremely troublesome to operate. Forcing the air charge through the meter pipe solved this problem.
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Unread postAuthor: D_Hall » Mon Sep 27, 2010 8:44 am

Technician1002 wrote:The idea behind the same pressure and two orifice sizes is it can be used for various delivery pressure while maintaining the same ratio, such as filling a 2 to 8X mix hybrid. It would even properly fill a vacuum purged chamber.

The same could be done via pressure control assuming your gas choice was appropriate (I was using acetylene, obviously you wouldn't want to use that on an 8X hybrid.). The difficulty isn't in arriving at a combustible mix, the difficulty is in arriving at the desired X mix.
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