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 68 users online :: 5 registered, 0 hidden and 63 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

QEVs.... on a hybrid?

Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
Sponsored 
  • Author
    Message

QEVs.... on a hybrid?

Unread postAuthor: Fnord » Sat Oct 06, 2007 6:05 pm

Has anyone ever tried this?
A qev is essentially a piston valve, and seeing how metal piston valves are such an effective alternative to a burst disk, I can't see why a qev wouldn't work.

The best part is they are already made to a high standard, so it would be an extremely good option to those who don't have access to a welder of some type.

Tell me what you think. I'm interested to see if this could be a "burst disk killer" idea. An idea to bring valved hybrids to the masses :)


Edit:You shouldn't even need to use a pop-off, actually. This will cause the valve to open at a higher pressure and increase overall preformance.
  • 0

Last edited by Fnord on Sat Oct 06, 2007 6:14 pm, edited 2 times in total.
Image
User avatar
Fnord
Major General
Major General
 
Posts: 2244
Joined: Tue Feb 13, 2007 9:20 pm
Location: Pripyat
Reputation: 7

Unread postAuthor: windshrike » Sat Oct 06, 2007 6:09 pm

I suppose you intend to use a pop-off valve as the pilot?
  • 0

User avatar
windshrike
Sergeant Major
Sergeant Major
 
Posts: 178
Joined: Thu Jun 28, 2007 4:23 pm
Reputation: 0

Unread postAuthor: HaiThar » Sat Oct 06, 2007 6:10 pm

windshrike wrote:I suppose you intend to use a pop-off valve as the pilot?


Oh, that's good. I wouldn't have thought of that :P
  • 0

User avatar
HaiThar
Donating Member
Donating Member
 
Posts: 227
Joined: Fri Sep 14, 2007 12:12 am
Reputation: 0

Unread postAuthor: CpTn_lAw » Sat Oct 06, 2007 6:14 pm

i think the rapid build up of the pressure would cause too much stress to the valve. Plus, a lot of QEV's are rated to 150 psi. In addition, a hybrid generates about 300 + psi in a few miliseconds. So you'd overpass the pressure rating by a factor of 2. However, i'm not familiar with QEV's, so i might not be a good advise.
  • 0

"J'mets mes pieds où j'veux, et c'est souvent dans la gueule."
User avatar
CpTn_lAw
Brigadier General
Brigadier General
 
Posts: 987
Joined: Sun Sep 11, 2005 9:10 am
Location: France
Reputation: 0

Unread postAuthor: Novacastrian » Sat Oct 06, 2007 6:15 pm

Even a pop off valve would react too slowly i think. It would be cool if it was able to be done easily, but i doubt that it could be.
Burst discs are cool to use anyway, if i aint broke.....
  • 0

America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

Novacastrian
Major General
Major General
 
Posts: 1604
Joined: Sat Aug 11, 2007 6:59 pm
Reputation: 0

Unread postAuthor: windshrike » Sat Oct 06, 2007 6:19 pm

CpTn_lAw wrote:i think the rapid build up of the pressure would cause too much stress to the valve. Plus, a lot of QEV's are rated to 150 psi. In addition, a hybrid generates about 300 + psi in a few miliseconds. So you'd overpass the pressure rating by a factor of 2. However, i'm not familiar with QEV's, so i might not be a good advise.


But he just needs the QEV to hold the pressurized air and fuel in until ignition. As soon as the pressure exceeds the pop-offs rating, the QEV will open, releasing the majority of the expanding gases.

The pop-off would open very quickly because of the pressure spike and the pilot would be very small.
  • 0

User avatar
windshrike
Sergeant Major
Sergeant Major
 
Posts: 178
Joined: Thu Jun 28, 2007 4:23 pm
Reputation: 0

Unread postAuthor: PVC Arsenal 17 » Sat Oct 06, 2007 6:26 pm

I pondered this idea many times. I was always turned away by my fear of hybrids. Oh well.

But assuming you had a QEV that could handle the stress, and an extremely efficient pop-off to vent it, there is no reason why this shouldn't work.
  • 0


PVC Arsenal 17
Major General
Major General
 
Posts: 1762
Joined: Mon Mar 27, 2006 4:18 pm
Location: United States
Reputation: 1

Sponsored

Sponsor
 


Unread postAuthor: wannabie » Sat Oct 06, 2007 6:27 pm

I dont see why it wouldnt work. but the only QEV's i can get are diaphragm ones and im afraid it might burst the diaphragm, but if i could get my hands on a piston QEV i might try it.
  • 0

In epoxy we trust.
User avatar
wannabie
Captain
Captain
 
Posts: 304
Joined: Sun Apr 15, 2007 11:44 pm
Location: Australia
Reputation: 0

Unread postAuthor: veginator » Sat Oct 06, 2007 6:56 pm

All qev's are diaphram valves he is just saying it is very similar to a piston valve.
  • 0

User avatar
veginator
Sergeant Major
Sergeant Major
 
Posts: 186
Joined: Tue Apr 10, 2007 4:02 pm
Reputation: 0

Unread postAuthor: BC Pneumatics » Sat Oct 06, 2007 7:20 pm

We are overlooking that if the valve misfires, you have potentially created a bomb.
I do not think this is the solution to the "Burst disk problem"
  • 0

<a href="http://www.bcarms.com/"><img src="http://www.bcarms.com/images/store_logo.png" border="0"> </a>
User avatar
BC Pneumatics
Donating Member
Donating Member
 
Posts: 1089
Joined: Tue Jan 18, 2005 6:55 pm
Location: Fresno, CA
Reputation: 0

Unread postAuthor: LikimysCrotchus5 » Sat Oct 06, 2007 7:31 pm

I know i shouldn't be asking this but in a hybrid, you use a mix of of a combustable fuel (propane) and air pressure. Then i thought it was actuated by usuing some kind of heat source, stun gun or bbq lighter, opening the burst disk and letting out the pressure, tell me if on wrong and what im wrong on.
  • 0

User avatar
LikimysCrotchus5
Brigadier General
Brigadier General
 
Posts: 1100
Joined: Tue Sep 04, 2007 10:16 pm
Reputation: 0

Unread postAuthor: DYI » Sat Oct 06, 2007 7:40 pm

I don't think you have created a bomb as long as all the chamber parts are rated for more pressure than the combustion can produce. The QEV could be damaged by the strain though.

Hybrids work by combusting a pressurised fuel-air mixture. When the pressure reaches the failure pressure of the disk, the disk bursts, releasing the pressure and firing the launcher.
  • 0

Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
User avatar
DYI
Lieutenant General
Lieutenant General
 
Posts: 2861
Joined: Sat Jul 07, 2007 8:18 pm
Location: The People's Republic of Canuckistan
Country: Turks and Caicos Islands (tc)
Reputation: 9

Unread postAuthor: BC Pneumatics » Sat Oct 06, 2007 7:59 pm

There is a difference between the pressure generated, and the initial shock of the combustion. PVC is NOT rated for shock pressure, it is intended for use with static pressures.
The impulse from a hybrid in a closed PVC system would no doubt make a bomb.
  • 0

<a href="http://www.bcarms.com/"><img src="http://www.bcarms.com/images/store_logo.png" border="0"> </a>
User avatar
BC Pneumatics
Donating Member
Donating Member
 
Posts: 1089
Joined: Tue Jan 18, 2005 6:55 pm
Location: Fresno, CA
Reputation: 0

Unread postAuthor: homedepotpro » Sat Oct 06, 2007 9:42 pm

don't QEVs have a rubber/plastic diaphragm, wouldn't the heat from the combustion eventually damage/melt it.
  • 0

Image
User avatar
homedepotpro
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 443
Joined: Sun Nov 26, 2006 1:00 am
Reputation: 0

Unread postAuthor: wannabie » Sat Oct 06, 2007 9:54 pm

veginator wrote:All qev's are diaphram valves he is just saying it is very similar to a piston valve.


No there not, the QEV on Hotwired's copper head prime is a piston one.
  • 0

In epoxy we trust.
User avatar
wannabie
Captain
Captain
 
Posts: 304
Joined: Sun Apr 15, 2007 11:44 pm
Location: Australia
Reputation: 0

Next

Return to Hybrid Cannon Discussion

Who is online

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

Reputation System ©'