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by Doc j
Mon Jun 15, 2020 4:19 am
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Re: Ideas for biodegradable cannon-balls

Make molds with gap sealer silicon mixed with cornflour makes a putty B4 it sets.

Maybe this, wat put into Mold.
But it shrinks a bit I think.

by Doc j
Mon Jun 22, 2020 10:17 am
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Re: "Sabotless" Semi-Automatic Shotgun Concept

I was having a bit of a think about this idea and it seems it could be greatly simplified and also made more efficient: https://i.imgur.com/Csm81PX.gif The piston itself becomes the hammer that opens an inline balanced valve. Sorta thinking out loud. Piston be generating air infront of it, as heade...
by Doc j
Fri Jul 03, 2020 8:43 pm
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Re: Confused. Cylinder chamber to barrel ratio for compressed air.

If you have the same air volume and the chamber is 1/3 the volume, the pressure will increase by 3x. https://www.omnicalculator.com/physics/boyles-law Interesting to note. Apllying my reasoning, punch into calculator. As cylinder reduces in volume. increases the pressure to compensate for The loss ...
by Doc j
Thu Jul 02, 2020 12:03 am
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Re: Brass as the foundation of a projectile?

How would hollow cylinder and sabot go.
Someone's thought about it.
by Doc j
Fri Jul 17, 2020 12:30 am
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Re: Calculations related to pneumatic cannon.

Maybe Just do a vacuum cannon.
Be simplest.
Plunger, Aluminium foil for burst disk.
Use a ping pong ball or tennis ball.
Be more in the "high school" theme.
Safer for demonstration.
Just my two bobs.
by Doc j
Wed Dec 28, 2022 11:29 pm
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Re: Hpa Dump valve ? Discussion points.

Hi Maybe someone with more experience with the GGDT , Can explain why in the Dump ( 9999+ ms ) of valve . In the results section : the pressure drop is not equal to the pressure in chamber . ( Train of thought if volume of chamber is completely dumped , it would equal the pressure Drop .?) Outside o...
by Doc j
Wed Dec 21, 2022 1:41 am
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Re: Hpa Dump valve ? Discussion points.

As above .
But in relation to point 2.
by Doc j
Wed Dec 21, 2022 1:33 am
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Re: Hpa Dump valve ? Discussion points.

Ran scenarios through GGDT.
Regards to point 1.
.30 gram BB @ 5.95 mm
.603cm I'd barrel @ 43 cm long
Assuming 1.52cm3 dead space.
Asummed Nozzle , 5 mm I'd . Same as seat ?
by Doc j
Wed Dec 21, 2022 12:04 am
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Hpa Dump valve ? Discussion points.

Hi All , Not promoting anything so altered out names . Product Description : The ****** is a fixed volume system so only the air contained within the ******* cylinder is released down the barrel when fired. Therefore you use pressure to offset the need for more air volume to properly fill the barrel...
by Doc j
Tue Nov 28, 2023 6:41 am
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Re: Valve reliability

I like the last animation .
With the Grub screw restrictor to adjust the air port so then adjust closing time of valve .