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A no valve no chamber airgun idea:

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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A no valve no chamber airgun idea:

Unread postAuthor: boyntonstu » Sun Jul 05, 2009 8:58 am

I enjoy taking ideas from different arenas and combining them into a new invention:

Listed below are YouTube links that lead me to a slingshot airgun:

If you have the patience, view the videos and see if you agree with my train of thought.

Airowgun
http://www.airowgun.com/pellet.php
A 60 lb bow shoots a pellet 600 fps.
Notice how far the compressed air must travel to reach the breech.

Homemade shock pump
http://www.youtube.com/watch?v=ywC04etbHVY
A plunger, a seal, and some copper tubing.
This bright young man made a pretty good one.


Wrist rocket speargun
http://www.youtube.com/watch?v=wQktYuxNCxQ
Combining a slingshot an a speargun.


Crossbow vs Slingshot comparison
http://www.ctmuzzleloaders.com/ctml_exp ... etbow.html
The slingshot was surprisingly comparable in performance.


Jorg Ultimate Slingshot
http://www.youtube.com/watch?v=B9lJ5FoXrek
Imagine what 4 of these bad boys could do.
This slingshot uses a non latex elastic rubber that is very powerful.


Slingshot rife
http://www.youtube.com/watch?v=s0hhF91mrsc
Pretty interesting idea.


Vice grip slingshot gun trigger
http://www.youtube.com/watch?v=RM5kaZA0I8M
One possibility for a quick and easy trigger.

I ‘see’ this prototype test:

Assume a .8” diameter barrel about 36" long mounted on a rifle/speargun stock.
(cross section is almost exactly .5 sq in.)

Assume 4 ea 50 lb rubbers (200 lb) that will travel 12”

The 200 lb force on the .5 sq in piston will generate 400 psi.

A .8” OD hardwood bolt 14" long cut from a dowel.

Nock: Cut a nock into the end of the bolt.
or Fit on a nock made from plastic, aluminum, steel, etc.

Trigger holding point on the bolt:

Cut 2 notches into the bolt 180* apart near the nock
or Make spurs as part of the fit on nock.

Plunger/piston seal:

Cut "O" ring grooves into the dowel
Or use Screw/steel washer/rubber washer/steel washer. etc.

How it would operate:

Piston outside the barrel, load projectile into the breech.

Manually push projectile into the barrel with piston and retract to leave air space.

Lock the piston to the rifle trigger mechanism.

Using stirrup cock the 200 lb pull to the nock
Or pull back each rubber individually.
Lock the rubbers to the nock so that the piston will not be released.


It may be necessary to lock the piston in position to prevent blowback.

Aim, release trigger.

Repeat.

A no valve, 400 psi, no chamber air rifle!

What do you think?

BoyntonStu
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Unread postAuthor: pizlo » Sun Jul 05, 2009 11:06 am

Do you even read these forums? this is the second stupid topic you've made today, it was said like a week ago that lb of force and surface area cannot get you an accurate PSI Energy transfer and all. ALSO you will never get near that pressure unless your ammo is a perfect seal and gets held in till the perfect time.

Godamnit read before you post, and stop clogging these forums with your crap.

and

your

post

is

annoying

with

all

the

spaces!
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Unread postAuthor: mark.f » Sun Jul 05, 2009 12:07 pm

pizlo wrote:Do you even read these forums? this is the second stupid topic you've made today, it was said like a week ago that lb of force and surface area cannot get you an accurate PSI Energy transfer and all. ALSO you will never get near that pressure unless your ammo is a perfect seal and gets held in till the perfect time.

Godamnit read before you post, and stop clogging these forums with your crap.

and

your

post

is

annoying

with

all

the

spaces!


What's your problem? This post was actually well put together and not stupid at all. While some technical points (like the pressure not approaching 400 PSI) are invalid, "What do you think?" does not mean to call him stupid.
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Unread postAuthor: pizlo » Sun Jul 05, 2009 12:49 pm

This is a bad Idea from the start and has been discussed very recently. I was too harsh, but this idea will yield pitiful results, and a normal spudder would be far better and easier. I guess I jjsut want him to know that.
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