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QEV+popoff experiment - update: NOW WITH AMMO!

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Unread postAuthor: Ragnarok » Tue Mar 31, 2009 4:54 pm

psycix wrote:Can anyone use audacity or something like that to determine the ROF?

Actually, I tried this earlier. It's fast enough that it's pretty hard to clearly make out on Audacity, but I believe it hits around 2400-2500 rpm, around 40 "shots" per second.

During the endurance test, ROF was about 650 rpm, which makes for about 700 shots during the test. No, I am not going to count them individually.
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Unread postAuthor: jwilson7 » Tue Mar 31, 2009 6:06 pm

I can't imagine what its gonna do to targets with ammo. :D Just wondering... what are you gonna use this for? Because it would be great in airsoft with a more portable air supply setup. And when you build the blowforward bolt for good ammo reloading.
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Unread postAuthor: Davidvaini » Tue Mar 31, 2009 8:00 pm

I know you dont have your chronograph yet but can you do a poor mans chronograph with some .20g Airsoft BB's?

http://www.redwolfairsoft.com/redwolf/a ... ulletID=34

just load a single bb in for a single shot to test it.
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Unread postAuthor: Lentamentalisk » Tue Mar 31, 2009 9:13 pm

Herm... Rag, I am not sure about those numbers. Maybe I am just looking at the wrong section, but at the part in the middle of the third video, I was reading a solid 10rps.
Oh wait, that was during the endurance test.
I can't imagine how you could pick out anything on Audacity during the speed test. it was all a blur for me.

btw, thanks for getting me into audacity Rag
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Unread postAuthor: c11man » Tue Mar 31, 2009 9:24 pm

HOLY CRAP!!!

insane ROF!!!

only question is if a popoff from mcmaster would work? in the description it says that it opens a little just above the pressure and opens when the pressure increases and is fully closed again when it is a the specified pressure.
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Unread postAuthor: POLAND_SPUD » Tue Mar 31, 2009 9:34 pm

only question is if a popoff from mcmaster would work?
yes

insane ROF!!!

indeed it is insane but I am not sure if a blow forward bolt could keep up with it
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Unread postAuthor: Ragnarok » Tue Mar 31, 2009 10:18 pm

Lentamentalisk wrote:Maybe I am just looking at the wrong section, but at the part in the middle of the third video, I was reading a solid 10rps.

Like I said, I was getting about 650 rpm, which isn't far off 10 rps. But you've already said that.

I can't imagine how you could pick out anything on Audacity during the speed test. it was all a blur for me.

It wasn't easy, but there is just enough definition in there that I could get a number I'm pretty sure is right.

There are also some lateral thinking methods to make it easier. Simplest of them is creating another sound file that repeats firing noises at the rate you think is right, then see if it sounds the same - or equally, if it's faster/slower, adjust until it sounds right.

btw, thanks for getting me into audacity Rag

Not a problem.
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Unread postAuthor: Davidvaini » Tue Mar 31, 2009 10:31 pm

if you use airsoft BBs why not just install a metal hopup chamber to the barrel, they can keep up with 40rps and you would have the extra added accuracy from the hopup as well.

This is why I want to know the velocity of this thing with .20g 6mm Airsoft BB's because If its decent then I want to make one with an Metal hopup chamber for feeding.
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Unread postAuthor: rna_duelers » Tue Mar 31, 2009 11:14 pm

Awesome!

Love the video and especially the "Holy crap Dude" part :D

That has some nice ROF when connected to the tank,hope you can get a working feed system to keep up with it's cycling.
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Unread postAuthor: Lentamentalisk » Tue Mar 31, 2009 11:25 pm

One thing you might want to consider trying is whether you can mod the QEV to fill chamber side, hopefully greatly increasing efficiency.
Other than that, this is looking amazing.
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Unread postAuthor: jackssmirkingrevenge » Tue Mar 31, 2009 11:58 pm

POLAND_SPUD wrote:indeed it is insane but I am not sure if a blow forward bolt could keep up with it


Very good point, I personally would not go beyond 200 or so round per minute. Lower ROF also gives the chamber time to refill properly, so technically you should get MOAR POWER! :)

Also, what's with the tnak? Is it a typo gone wrong or simply a Dutch thing? In that latter case, don't even bother explaining :roll: :D
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Unread postAuthor: starman » Wed Apr 01, 2009 1:03 am

I verified the audio with Wavelab and found the "endurance run" varying anywhere between 570 and 700 rpm after initial startup. While it is difficult to see the impulses (room echo blurs primarily) in the all-out run, in several different samples, I found numbers fairly consistently in the 2600-2800+ rpm range.

This is pretty amazing performance for a basic pop-off spring AND the QEV itself!!
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Unread postAuthor: jackssmirkingrevenge » Wed Apr 01, 2009 1:33 am

starman wrote:This is pretty amazing performance for a basic pop-off spring AND the QEV itself!!


Amazing but in my view not desirable for such a setup, at those rates you might as well have a cloud BBMG.

I'm aiming for something like the AA-12, that fires at around 300 rounds per minute.

[youtube]http://www.youtube.com/watch?v=hhstuvzMiB0&feature=related[/youtube]
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Unread postAuthor: Carlman » Wed Apr 01, 2009 2:33 am

Gday guys,

back in the day soon after i made this i tuned it onto an airsoft mortor. basically the same format but with the barrel on a 45 to the chamber and i also cut down the barrel by half.

i stuck a T on the pilot going to a ajustable popoff and the other side of T went to a needle valve and then to my compressor.

I ran it at 100psi and dialed it in to shoot every 5 secs or so, so i would drp one in then wait for it to fire then drop agin.

aaaannnyway the point is it had enough power to go through cans easily.

this is relating to the power questions BTW
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Unread postAuthor: psycix » Wed Apr 01, 2009 4:27 am

Thanks for the measuring guys. :D

40 rpm is very fast, and I also think that the BFWB will not be able to keep up, but that doesnt matter. I'm aiming for the lower ROF anyway (dakka dakka)
At least I now have an idea how large my mag will have to be.
JSR wrote:I'm aiming for something like the AA-12, that fires at around 300 rounds per minute.
Thats a nice rate of fire indeed. In the end, I am looking for powah!
Larger chamber, larger barrel, more efficient system ect. But first I gotta finish this one.

Another thing is that besides clouds/vortexes being pffffffrrrt, I wanted to get more power out of less air, yet still going full auto.

Davidvaini wrote:I know you dont have your chronograph yet but can you do a poor mans chronograph with some .20g Airsoft BB's?
There is a brand new chrony on the way as we speak.
Also I will be using .87 (or something around that) steel bb's, they are also being shipped to me now.
Advantage is that I can sweep a magnet to recover my bb's. And on top of that, they are HEAVY.

jwilson wrote:I can't imagine what its gonna do to targets with ammo. :D Just wondering... what are you gonna use this for? Because it would be great in airsoft with a more portable air supply setup. And when you build the blowforward bolt for good ammo reloading.
I plan to use it to shred cans and some other stuff.
The current air setup is quite portable, I plan to paint the tnak camo and make something to be able to wear it on my back. Short hose to the gun and I'm done.

Lentamentalisk wrote:One thing you might want to consider trying is whether you can mod the QEV to fill chamber side, hopefully greatly increasing efficiency.
Yep, I have a few ideas like that in mind for the future. This is only a prototype/tryout, but the next version will surely have something like that installed.

JSR wrote:Also, what's with the tnak?
It is the result of a typo combined with a lot of roflmao, supplemented by a bunch of lol. :D
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