Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 54 users online :: 5 registered, 0 hidden and 49 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

Registered users: Bing [Bot], Google [Bot], Google Adsense [Bot], MSNbot Media, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

pilot vent to close a blow forward bolt

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.
Sponsored 
  • Author
    Message

pilot vent to close a blow forward bolt

Unread postAuthor: iknowmy3tables » Tue Mar 09, 2010 7:06 am

so polandspud showed me this animation in another thread awhile back
Image
read carefully what I'm suggesting isn't the same as this animation
so in this system the piston that pushes the bolt forward can't be air tight and the restriction it creates on the pilot reduces power slightly, however I was thinking, for a regular blow-forward bolt attached to a 3way and qev, what if you connected the pilot exhaust to the front of the piston, perhaps the the pilot air might help close the blow-forward bolt either fully or partially before the qev opened so the main blast of air would encounter less resistance from the blow-forward bolt when it finally opens.
would the restriction on the pilot flow make this less powerful or would the reduced resistance for the air from the qev make this more powerful then the regular blow-forward setup
  • 0

Last edited by iknowmy3tables on Wed Mar 10, 2010 11:31 am, edited 2 times in total.

iknowmy3tables
Major General
Major General
 
Posts: 1558
Joined: Fri Dec 15, 2006 3:57 pm
Location: maryland
Country: United States (us)
Reputation: 0

Unread postAuthor: POLAND_SPUD » Tue Mar 09, 2010 3:18 pm

yeah that's a cool design and cool animation.. I had to look at it for 20 minutes or so to work out how it works :D

perhaps the the pilot air might help close the blow-forward bolt either fully or partially before the qev opened so the main blast of air would encounter less resistance from the blow-forward bolt when it finally opens
the problem is that the performance will be reduced if piloted air can't be vented freely... sure you can use a chamber to provide more volume for it to expand, or a larger pilot valve/small qev to assist piloting...

though, I think that it's more complicated than just the QEV + 3 way valve + air cylinder combo, which offers zero restrictions in the first place...

lol I guess I am being repetitive... I wrote at least 3 or 4 similar sentences today :D
  • 0

Children are the future

unless we stop them now
User avatar
POLAND_SPUD
Chief of Staff
Chief of Staff
 
Posts: 5405
Joined: Sat Oct 13, 2007 4:43 pm
Country: Israel (il)
Reputation: 10

Unread postAuthor: Patto » Tue Mar 09, 2010 4:23 pm

He he he echo, echo .... :lol:
  • 0

User avatar
Patto
Sergeant
Sergeant
 
Posts: 96
Joined: Wed Jan 20, 2010 7:08 pm
Reputation: 0

Unread postAuthor: iknowmy3tables » Tue Mar 09, 2010 7:36 pm

yeah but in this case what I'm just thinking of is not exactly what's in the animation, it just uses the concept

what I'm suggesting is just a conventional blowforward bolt with the pilot exhaust redirected to behind the bolt instead of the atmosphere,

I've already stated that the restriction of the pilot is a negative factor towards performance, however the reduced restriction on the qev output could make up for this
  • 0


iknowmy3tables
Major General
Major General
 
Posts: 1558
Joined: Fri Dec 15, 2006 3:57 pm
Location: maryland
Country: United States (us)
Reputation: 0

Unread postAuthor: BigGrib » Tue Mar 09, 2010 7:47 pm

ok here's my take on it, the line going to the bolt from the res in the back remove that and put it to the res by the piston, that way when you fill the chamber it'll blow the bolt forward, put a spring in there to slide the bolt back after discharge that way air pressure overcomes spring pressure to close the bolt and then dumping the pilot opens the piston and the spring jacks the bolt back.
  • 0

Yea, that's definitely going to get you at least a tazer.

<a href="http://www.youtube.com/watch?v=AkMkGOpAF4s">DONT TAZE ME BRO.. DONT TAZE ME... AHHHH</a>
facebook.com/biggrib
User avatar
BigGrib
Colonel
Colonel
 
Posts: 652
Joined: Mon Oct 01, 2007 11:43 pm
Location: TriCities, WA
Reputation: 0

Unread postAuthor: POLAND_SPUD » Wed Mar 10, 2010 2:54 am

perhaps the pilot air might help close the blow-forward bolt either fully or partially before the qev opened
hmm I've just noticed something... just to make sure I get your idea... you want to vent the volume between the QEV and the blowforward bolt, right ?? well there is one possible problem here

QEVs stay shut because of pressure differential pushing the piston/poppet against the sealing face... but then you direct air from the pilot side to the volume between the QEV and the blow forward bolt the pressure is almost the same on both sides of the piston/QEV... I wonder what would happen then and when the QEV open?


will it stay closed ? I don't know

will the QEV fire prematurely :D (before the BFB loads ammo) ? IDK

will the piston bounce back as soon as the QEV opens (since air can pass from the barrel side of the QEV to the pilot side of it... sure you can put a check valve there but that makes it more complicated)? IDK

what effect will it have on performance? IDK

anyway, it seems that the expected advantage of this design....
the main blast of air would encounter less resistance from the blow-forward bolt
might not be worth it at all
  • 0

Children are the future

unless we stop them now
User avatar
POLAND_SPUD
Chief of Staff
Chief of Staff
 
Posts: 5405
Joined: Sat Oct 13, 2007 4:43 pm
Country: Israel (il)
Reputation: 10

Unread postAuthor: iknowmy3tables » Wed Mar 10, 2010 7:28 am

@poland spud: I think you got it
the qev wouldn't stay closed, note that plenty of diaphragm valves that don't hold plain compressed air vent pilot volumes towards their outputs

but the rest of the uncertainties you mentioned, I'm pretty uncertain about this, which is why I posted this, cause I don't know

if it is true then anyone attempting a semiauto blowforward qev gun could make an easy adjustment to improve their gun
  • 0


iknowmy3tables
Major General
Major General
 
Posts: 1558
Joined: Fri Dec 15, 2006 3:57 pm
Location: maryland
Country: United States (us)
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: psycix » Wed Mar 10, 2010 7:38 am

I like this system. But it indeed has some possible issues.
I'd drill a vent hole in the side so that the blue part can move forward without compressing air.

It might need a checkvalve in the small line leading to the bolt to prevent the mentioned leak into the pilot of the red part, closing it.



The main advantage of this design is the simplicity. Especially the simplicity in manufacturing.
  • 0

Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Return to Pneumatic Cannon Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], Google Adsense [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'