I am sure someones posted on it or tried it before ... sparked some ideas for me though. thought you guys might like it. could really get that plane flying with the right gun. what do you think ???

whenever i have compatibility issues for programs i run them on a different o/s under http://www.virtualbox.org/ ...... always sorts it out. install virtualbox and run it, then install xp(if your currently on vista) as if your doing a fresh install and load up GGDT once xp is running under VB.

??? WTF.. Diameter is 0.408
your seat (marked as vent in your pic Smile ) seems quite large... have you measured its ID or OD ??
the .408 diam is the seat diam inside the piston. i marked it as vent diam on the pic i posted of the piston opened. sorry i should of made that clear.


do i need ...

i double checked and its definitely .408 ID .... 10.34mm


To find volume.. Take the cross section of the cylinder and multiply by length. To find the cross section, use Pi times the radius squared.

got some measurements of the piston barrel and tried to get the pilot valve volume, definitely ...

Piston mass - 0.1410958oz

according to the pic i just posted, vent = 0.408 seat = 0.591

excellent thank you so much, seing all the mistakes clear as day now.
I've taken the qev apart and measured and weighed all the parts i think i need too.

Just to make sure, have i got the correct idea about the seat and vent diameters in the picture below ?? as too which is which ??
http://i9 ...

the most i can get out of it is 167 ft/s .... with lighter projectile and trying different combinations of barrel length, chamber sizes and psi rating.

is 3/8 qev to 1/4 barrel just never going to shoot well ? not sure if should just scrap this gun and sell the qev etc or ignore the program and ...

when setting it as barrel sealing what would i put the piston diametre as ? figured its about .276inch ish ? even when i change it around the gun still has no power at all. cant figure this out for the life of me :(

i have searched ggdt to try and learn how it works im not being lazy ... just the ...

Oww i see hehe told you ide do something stupid, i've turned it down to zero and i am still getting the WRN: Barrel potentially choking flow WRN: Barrel choking flow messages ... any idea what i am doing wrong ??

Also, the stats in GGDT don't seem to reflect what you're talking about.
I tried ...

hello folks

the other day i picked up a qev and some fittings and was hoping to get some help on what would be the best chamber size and any other info that might help to make this a better gun, still real new to all this sorry. looking to make a smaller bore sniper rifle, somewhat like an air ...

nice one inonick cheers mate. starting to get a good grasp if it now.

was hoping to ask, in the ggdt program under the chamber data section.
what do you they mean by inner and outer diam ??

i was figuring inner diam was how wide the tubing used for chamber is and then the outside was just used to ...

I love that hunting camo dense bushland look, if could replicate that would be pretty sweet.

Thanks for all the info jacks and Co. I just finished glueing up a barrel a little over twice as long so that should shoot alot better. Im really interested to see the difference first hand ... and properlly shoot my gun for the first time, its on tommorow .. inanimate objects beware!

How ...

Thanks for the comments guys, will definatlly get some paint on it. And many more guns too come. Already started a brass gun :)

Can i ask how in general the chamber volume vs the barrel length works ? have you guys made that many guns that you just know by now that it needs a longer barrel or is ...

i know i know it looks horrid, coloured primer+cement / not cleaning anything up = abstract. the barrel that's actually on the gun is just a straight 20mm to use while i made a breech system. the 15mm barrel on the breech system is nearing twice as long.

i plan to shoot anything that looks fun and ...