TBMA-230 V2.0

Harness the power of precision mixtures of pressurized flammable vapor. Safety first! These are advanced potato guns - not for the beginner.
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POLAND_SPUD
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Sat Dec 03, 2011 12:38 pm

MOAR push-to-connect fittings
You used them becasue they make things easier... and that's why I have been I recomending them

What do you use as air source ? ever considered buying an old scuba tank and filling it with a fridge compressor?
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SpudBlaster15
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Sat Dec 03, 2011 2:00 pm

Lockednloaded wrote:I'm not much of a DCV guy, but couldn't a hybrid be fueled using only a 3/2 way and two regulators?
A manometrically metered burst disk hybrid could be fueled using a 3/2 DCV, two regulators (One of which would need to be extremely precise and accurate) and a ball valve to protect the DCV from combustion pressure, but I don't think it's possible to use that setup to fill the pilot chamber of a piston hybrid without additional valving.

A 5/3 DCV on the other hand allows all gas flows to be controlled with a single valve (Two if you count the chamber isolation valve which needs to be there anyway), and the neutral position enables the use of volumetric fuel metering, for which a standard air pressure regulator is perfectly suitable.
POLAND_SPUD wrote:You used them becasue they make things easier... and that's why I have been I recomending them
They definitely make the fuel/air routing system much more compact and less time consuming to set up. Had I known how inexpensive these fittings are at the local supplier, I would have been using them years ago.
What do you use as air source ?
Shop compressor if I'm near an electrical outlet, an el cheapo 12V air compressor (Hasn't failed yet) if I'm near my car, or a manual track pump.
ever considered buying an old scuba tank and filling it with a fridge compressor?
Yes, I was considering something along those lines when I was testing V1.0 last year, but I became sidetracked with helping SWIM toss nitro groups onto chain polyols, and ended up abandoning most launcher related projects.
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SpudBlaster15
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Mon Dec 05, 2011 2:50 am

Just in case I want to try an 'enhanced' mix or two...
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Gun Freak
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Mon Dec 05, 2011 6:29 am

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Mon Dec 05, 2011 6:33 am

Gun Freak wrote:jizzinpants
Since you're a strict pnemosexual, isn't that kinda... gay?
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Gun Freak
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Mon Dec 05, 2011 7:02 am

I like teh 3 way valvez
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POLAND_SPUD
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Mon Dec 05, 2011 5:08 pm

I like teh 3 way valvez
OMG subliminal messages do work...
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MrCrowley
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Tue Dec 13, 2011 1:58 am

Just noticed; how come your pilot gauge only goes to 160PSI? I guess it's possible to only need 160PSI for a 10x mix if you have a seat:sealing face ratio close to 1.
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SpudBlaster15
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Tue Dec 13, 2011 3:04 am

Four words: Extreme Piston Static Friction

160PSI is the maximum used in the pilot chamber, mostly because all of my high volume air supplies seem to disintegrate at beyond said pressure.
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SpudBlaster15
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Mon Dec 19, 2011 12:25 am

Not bad for $10 worth of 1.5" EMT conduit.
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daniel0663
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Mon Dec 19, 2011 1:32 am

Not bad at all for $10.
Can't go wrong with that..
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mark.f
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Mon Dec 19, 2011 9:29 am

Excuse me, sir, but you must immediately film, at the very least, a blank firing with this barrel to prove it's not a tuning fork like MrCrowleys. :P
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Mon Dec 19, 2011 3:09 pm

I believe Mjölnir's tuning fork behaviour is caused by the barrel support setup, which seems to allow for some high frequency vibration upon firing. This barrel is not likely to have similar issues, as it is well supported by a section of 2" ABS sleeved inside a 2" galvanized nipple.

Videos are on their way, but we recently received 25cm of snow, followed immediately by several hours of continuous freezing rain, so I doubt any of the roads to my test sites will be accessible for at least a few days. You're going to need to be patient. :P
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Wed Dec 21, 2011 6:04 am

Test fired it at 7X with the new barrel, and there was no sign of any tuning fork like behaviour, only a sharp crack and rolling echo. My earplugs were pressed in lightly, so the tone of the report was quite apparent.

No video, I couldn't be arsed to drag the camera through a snowy field and set it up in the dark. Sorry Mark, I'll film another shot soon. :wink:
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daniel0663
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Wed Dec 21, 2011 6:06 am

Very much looking forward to the new vid of the upgraded set-up... :P
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