Search found 40 matches

by Doc j
Fri Jul 17, 2020 12:30 am
Forum: Pneumatic Cannons
Topic: Calculations related to pneumatic cannon.
Replies: 9
Views: 1527

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
Sat Jul 11, 2020 2:07 am
Forum: Ammo & Parts
Topic: Brass as the foundation of a projectile?
Replies: 6
Views: 695

Re: Brass as the foundation of a projectile?

Doc j wrote:
Thu Jul 02, 2020 12:03 am
How would hollow cylinder and sabot go.
Someone's thought about it.
Aperently, This design, unless gets mach 3 and over.
Creates a dome shock infront.
Dunno if much be gained from it
From lower herbs.
Interesting non the less.
by Doc j
Fri Jul 10, 2020 2:10 am
Forum: BB, Airsoft, and Pellet Guns
Topic: Confused. Cylinder chamber to barrel ratio for compressed air.
Replies: 9
Views: 882

Re: Confused. Cylinder chamber to barrel ratio for compressed air.

Ended up getting Ggdt. To work On desktop pc. First time having a play around. Working off the above, Punched in details. On paper, Went to 1/8 th of cylinder start volume went x8 pressure 116psi. Gave only 18% better fps. (+33fps) Than the 14.5 psi on full cylinder volume. Helped can that direction...
by Doc j
Fri Jul 03, 2020 8:43 pm
Forum: BB, Airsoft, and Pellet Guns
Topic: Confused. Cylinder chamber to barrel ratio for compressed air.
Replies: 9
Views: 882

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
Forum: Ammo & Parts
Topic: Brass as the foundation of a projectile?
Replies: 6
Views: 695

Re: Brass as the foundation of a projectile?

How would hollow cylinder and sabot go.
Someone's thought about it.
by Doc j
Wed Jul 01, 2020 11:25 pm
Forum: BB, Airsoft, and Pellet Guns
Topic: Air Stapler
Replies: 6
Views: 597

Re: Air Stapler

My progress. Haha.... Mini... incremental. Just to see how it goes, I Pulled out piston. Put Schrader valve bottom handle , used foot pump. Didn't work at lower pressures. 70 to 90 psi did. It air hungry, pretty much whole volume gone in one pull. I changed spring and length in back of piston valve ...
by Doc j
Wed Jul 01, 2020 11:07 pm
Forum: BB, Airsoft, and Pellet Guns
Topic: Confused. Cylinder chamber to barrel ratio for compressed air.
Replies: 9
Views: 882

Re: Confused. Cylinder chamber to barrel ratio for compressed air.

Are you working on something that you had a question about? I lost sight of what you were trying to do.
[/quote]

Yeah,
I posted "air stapler"
In another topic.

For simplistic sake it might end up manual bolt yet.
Might try blow forward later.
by Doc j
Wed Jul 01, 2020 6:48 pm
Forum: BB, Airsoft, and Pellet Guns
Topic: Confused. Cylinder chamber to barrel ratio for compressed air.
Replies: 9
Views: 882

Re: Confused. Cylinder chamber to barrel ratio for compressed air.

Talking about both volume and pressure. For a determined Barrel to cylinder / chamber ratio. Without changing barrel volume. Just working on cylinder and pressures to volume. I could be wrong too, seen somewhere take 1 bar off regulated pressure gives actual reg pressure. In that case suppose adjus...
by Doc j
Wed Jul 01, 2020 6:25 am
Forum: BB, Airsoft, and Pellet Guns
Topic: Confused. Cylinder chamber to barrel ratio for compressed air.
Replies: 9
Views: 882

Re: Confused. Cylinder chamber to barrel ratio for compressed air.

If you have the same air volume. You mean same pressure. That calculator shows if compress 21. 5 psi to A third of its volume increases presurre x3 No you don't have same volume. But Yes a higher pressure. Thats where I get confused and was saying. Regulate pressure at higher to compensate for loss...
by Doc j
Tue Jun 30, 2020 7:16 am
Forum: BB, Airsoft, and Pellet Guns
Topic: Confused. Cylinder chamber to barrel ratio for compressed air.
Replies: 9
Views: 882

Confused. Cylinder chamber to barrel ratio for compressed air.

Hi. Got a cylinder volume to barrel ratio. Want to use on diff build. I got it from a AEG. Crono found sweet spot. For diff build using air pressure. Not spring. If I up the psi, would that mean to use a smaller chamber./ cylinder. Bare with me. Worked out cylinder volume. To Guestimate pressure Goi...
by Doc j
Mon Jun 29, 2020 4:02 am
Forum: Pneumatic Cannons
Topic: "Sabotless" Semi-Automatic Shotgun Concept
Replies: 19
Views: 4425

Re: "Sabotless" Semi-Automatic Shotgun Concept

Gettin lost in What proposed to do. If drive piston quik. Would this work. Disregard. Force output would be significantly less. Guess at : If was 30mm I'd cylinder at 7 bar equates to 495 newton's output force shaft. . If piston became valve I'd. At 7mm cylinder I'd. Out put be 30.9 newton's using ...
by Doc j
Sun Jun 28, 2020 9:28 am
Forum: Pneumatic Cannons
Topic: "Sabotless" Semi-Automatic Shotgun Concept
Replies: 19
Views: 4425

Re: "Sabotless" Semi-Automatic Shotgun Concept

Gettin lost in
What proposed to do.
If drive piston quik.
Would this work.
by Doc j
Tue Jun 23, 2020 2:30 am
Forum: BB, Airsoft, and Pellet Guns
Topic: Air Stapler
Replies: 6
Views: 597

Re: Air Stapler

https://i.imgur.com/IXFQ1Ji.jpg A good diagram of how it works Thanks. Found another, explains the small holes in cylinder for piston return, in that diagram nailer is fed from Seperate chamber. I think could do, hav to block above the trigger. Makes the around white plastic storage pressure volume...
by Doc j
Tue Jun 23, 2020 2:15 am
Forum: BB, Airsoft, and Pellet Guns
Topic: Air Stapler
Replies: 6
Views: 597

Re: Air Stapler

This was bit of inspiration.
For build.

by Doc j
Mon Jun 22, 2020 10:17 am
Forum: Pneumatic Cannons
Topic: "Sabotless" Semi-Automatic Shotgun Concept
Replies: 19
Views: 4425

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...