Search found 61 matches

by Alanstone
Mon Jan 07, 2019 3:53 pm
Forum: Miniature Guns
Topic: HAC- II- R
Replies: 23
Views: 29262

Re: HAC- II- R

In the case of using cartridges that include the rupture disc, you simply load the gas before inserting the cartridge. Hectmarr, is the cartridge your firing chamber? If that is the case I think it's greatest benefit is being able to eject the hot cartridge. I am concerned about heat generation wit...
by Alanstone
Fri Jan 04, 2019 11:57 pm
Forum: Miniature Guns
Topic: HAC- II- R
Replies: 23
Views: 29262

Re: HAC- II- R

Do you say the pressure is to high because of your butane measuring system?
by Alanstone
Fri Jan 04, 2019 1:04 pm
Forum: Miniature Guns
Topic: HAC- II- R
Replies: 23
Views: 29262

Re: HAC- II- R

Hectmarr you've done some excellent work with regard to your hybrid projects. Congratulations. I've been thinking along these lines: A https://www.ansgear.com/Ninja_Adjustable_Tank_Regulator_4500_PSI_p/ninjatank-reg45.htm adjusts from 450psi. With a stoemetric ratio of 31:1, you can your flush your ...
by Alanstone
Wed Nov 16, 2016 10:39 am
Forum: Pneumatic Cannons
Topic: Valve flow coefficient question.
Replies: 3
Views: 2298

Re: Valve flow coefficient question.

Thanks for taking the time to reply Matti. I am aware of the GGDT user guide info and that it suggests 30-50% efficiency. Here is my problem though. I was looking at 1/2" QEV'S on the net to try get a feel for what kind of Cv they have and came across numbers I did not expect. This 1/2" QEV is rated...
by Alanstone
Tue Nov 15, 2016 3:30 am
Forum: Pneumatic Cannons
Topic: Valve flow coefficient question.
Replies: 3
Views: 2298

Valve flow coefficient question.

I have a barrel sealing piston of 12mm diameter. When unseated, the CO2 flows into 4 separate 6 mm diameter holes into the barrel. Is it possible for someone who has a feel for these things to give me your gut feel on what the valve flow coefficient will be? I have attached a few pictures so that yo...
by Alanstone
Tue Nov 01, 2016 1:35 pm
Forum: Combustion Cannons
Topic: Simple Pump Action Design
Replies: 10
Views: 6103

Re: Simple Pump Action Design

Looking good. It's coming along nicely. I am looking forward to how your project works out.
by Alanstone
Wed Oct 26, 2016 2:04 am
Forum: Pneumatic Cannons
Topic: Arrow gun: Barrel length vs fps question.
Replies: 18
Views: 7799

Re: Arrow gun: Barrel length vs fps question.

@ mrfoo "If you're holding the arrow back until the barrel pressure reaches a certain level, you can consider your barrel to be the chamber, and your arrow to be the piston. At that point, you're probably better off working out a way to make the barrel seal properly against the arrow, forget any hig...
by Alanstone
Mon Oct 24, 2016 11:28 pm
Forum: Pneumatic Cannons
Topic: Arrow gun: Barrel length vs fps question.
Replies: 18
Views: 7799

Re: Arrow gun: Barrel length vs fps question.

You have the workings right sharpshooter. The shroud is there to protect the barrel and it looks neater too,in my opinion. There is 2.8 "cu co2 in the valve but it looks like I may have to increase that. Although it's a work in progress, here is a rendering of the launcher further along in its design.
by Alanstone
Sat Oct 22, 2016 5:09 pm
Forum: Pneumatic Cannons
Topic: Arrow gun: Barrel length vs fps question.
Replies: 18
Views: 7799

Re: Arrow gun: Barrel length vs fps question.

Thanks for your input D_Hall. If I held the arrow back until the pressure reached 850 psi in the barrel, the dead space would be zero right? Auxiliary, is your launcher still operational? Can you remember what the diameter of the piston is? I am assuming it's around 12.6 mm. How is the spring and bu...
by Alanstone
Sat Oct 22, 2016 4:15 pm
Forum: Combustion Cannons
Topic: Simple Pump Action Design
Replies: 10
Views: 6103

Re: Simple Pump Action Design

Hi Jean. Good luck with your project. You say you are printing the parts in pla and then going to glue them together. What glue are you going to use for that?
by Alanstone
Wed Oct 19, 2016 2:28 pm
Forum: Pneumatic Cannons
Topic: Arrow gun: Barrel length vs fps question.
Replies: 18
Views: 7799

Re: Arrow gun: Barrel length vs fps question.

Now just to get pictures instead of ray tracings - mark.f Much water needs to flow under the bridge before we get to photographs! :lol: I have use of a 3D printer in December (perhaps a little sooner) with which I will do as much prototyping as I can. In the meantime I need to get from the 3D desig...
by Alanstone
Wed Oct 19, 2016 2:07 am
Forum: Pneumatic Cannons
Topic: Arrow gun: Barrel length vs fps question.
Replies: 18
Views: 7799

Re: Arrow gun: Barrel length vs fps question.

I went to a paintball shop yesterday and found out about remote lines and pneumatic fittings. So the above is meant to be run off a remote line. At the same time I would like to see if I can fit a 9oz bottle ahead of the trigger and have a microline running to the valve. I would be ok with having it...
by Alanstone
Wed Oct 19, 2016 1:56 am
Forum: Pneumatic Cannons
Topic: Arrow gun: Barrel length vs fps question.
Replies: 18
Views: 7799

Re: Arrow gun: Barrel length vs fps question.

Do you mean something like this? :lol:
by Alanstone
Mon Oct 17, 2016 9:20 am
Forum: Pneumatic Cannons
Topic: Arrow gun: Barrel length vs fps question.
Replies: 18
Views: 7799

Re: Arrow gun: Barrel length vs fps question.

Thank for the answer Jimmy101. Thanks for the compliment farcticox1.
by Alanstone
Sun Oct 16, 2016 5:02 am
Forum: Pneumatic Cannons
Topic: Arrow gun: Barrel length vs fps question.
Replies: 18
Views: 7799

Arrow gun: Barrel length vs fps question.

Greetings spuddy buddies! I have been designing a pneumatic arrow launcher and have a question I am hoping someone will be willing to answer. The design is not complete but I am getting there. Firstly, the arrow gun uses a QDV. Credit for inspiration must go to Technician 1002 and Auxiliary. Here is...