Am in process of designing an air cannon using a QDV set up. Aquired a large propane tank for free (4 ft tall and about 16 inches diameter).
plan is to install a 2 inch galvanized pipe down the middle for the valve cylinder but was wondering if 2 inch exhaust pipe would work as well?. for sure ...

yea it could get hevy for sure.
maybe just a little water and lots of dry ice = lots of fog??
going to have local welding shop do the welding anyway. I am going to do the small propane cylinder by brazing.

WAs playing around with the GGDT program and my computer crashed!
all I was doing was changing values and see what happens.
any one else experience same?

I like the idea of dry ice.
I wonder if I filled tank with water, droped some weighted dry ice (so it won't float) into tank then proceeded to cut and weld
On the subject of welding, contemplating on using exhaust pipe.
cheaper that 2inc galvanized and smoother inside.
this is for the valve cylinder?

I found two large (about 4ft tall) propane tanks that are for FREE
Question concerns safety in cutting and welding of tanks.
I understand that removing the valve then dropping dry ice into tank will rid tank of any flammable gas or is there a better way.
leaving out in weather upside down(valve end ...

The schematic I posted does need a second sensor for the wind direction. Thinking about a ps2 mouse method of direction sensing.
I like the dry ice idea.

was concerned about North but thinking about it all I need is a reference position or HOME position to start for the direction setting.
have a 8-10f pole with weather stuff on top. lock the wind vane. then have aiming tube or sight , point at target from behind cannon with barrell pointed at targe ...

latest electronics schematic
need to tweek and write code.
test each segment seperatly -air pressure, wind speed, wind direction then muzzle velocity.
THEN combine the codes into one. http://i992.photobucket.com/albums/af44/MrDEB/chrono2.jpg
and yes if anyone is wanting to assist or when I get it ...

my latest additions
plan to use a small propane canister (used from camping) for trigger air tank. thinking why take away air from the main chambers for triggering. may not be consistent.
have an isolation ball valve so I can fill both chambers up but at say 10psi, close ball valve and continue ...

yes a stand with elevation and mounted on an adjustable and lockable truant.
aim at target, adjust for wind, adjust air pressure using digital readout, then corrlating for muzzle velocity and BAM! hit on the target every time.
Or at least hope to.

planning on building with a seperate air chamber as I posted drawing(see above) using a QDV actuacted by a spk valve triggered piston (back to back air cannons)
using this method will hopfully add to consienty and less operator error (jarring the barrell while pulling rod or rope) as well as opening ...

QUESTION?
which valve is desired for power and which one for accuracy (consistent firings)
The QDV vers the barrel sealing valve

What video are you talking about
Haven'yt seen a QDV w/o a rod??

the PIC will just display data such as wind speed, muzzle velocity etc.
no real cals as to what pressure to hit target at X distance.
this will all be drawen up using actual test firings/data retrieval then drawing up graphs using data that was aquired.
need to test on windy days as well as calm ...

If I am reading Techs info right, if we use a sabot in the barrel for the short distance shots we will be more accurate?
on the subject of sabots, what material are you recommending?
could one be made of homemade marshmallows?
Fr the pressure transducer, going to connect to a micro-controller chip ...