Author Topic: Project Fury 20mm BIGbore. 3100FPE! (Read 86467 times - 2 votes)
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rkr · « **Reply #220 on:** July 19, 2017, 01:38:32 PM »

Quote from: Finn on July 19, 2017, 05:52:59 AM

I didn't even think that the suppressor would make this gun silent (they rarely do), it was just interesting to think how large the can would have to be to get any notable effect on recoil or sound.

I've used the can I mentioned at 150 fpe level and it's roughly equal to HW can at 30 fpe level.

rsterne · « **Reply #221 on:** July 19, 2017, 04:16:51 PM »

OK, so with a 450 cc reservoir, a 265 bar fill, and 200 bar after the shot, the volume of air used is (450/16.4) x (265-200) = 27.4 CI x 65 bar = 1784 CI.... For a shot of 2447 FPE, that is an efficiency of (2447/1784) = 1.37 FPE/CI.... which is astoundingly good....

If for the same shot you used 80 bar, then we have 27.4 x 80 = 2192 CI, and the efficiency would be (2447/2192) = 1.12 FPE/CI.... If we use a few reasonable assumptions, Lloyd's Internal Ballistics Spreadsheet models the results as follows....

With a 65 bar drop the air used is 450 x 65 = 29,250 cc.... and the residual muzzle pressure with a 43" barrel should be about 840 psi.... approx. 70% efficiency, with the valve closing when the bullet is about 18" from the breech, with a valve dwell of 5.1 mSec....

With an 80 bar drop the air used is 450 x 80 = 36,000 cc.... and the residual muzzle pressure with a 43" barrel should be about 1170 psi.... approx. 64% efficiency, with the valve closing when the bullet is about 23" from the breech, with a valve dwell of 6.2mSec....

Substituting Helium, and only compensating for the mass difference, but using the same valve dwells, it predicts about 2800-2850 FPE.... What it can't calculate is if using Helium will change the valve dwell compared to air, or if there is an effect from the smaller molecules, this is solely based on the reduced mass of Helium compared to air....

Bob

QVTom · « **Reply #222 on:** July 19, 2017, 04:46:47 PM »

Marko,

I must say this is a fascinating project, I'm very impressed with your progress and your ability to get it done! The most amusing part for me is the barrel has a larger OD than the the airtube LOL; the most interesting part for me is the performance analysis because this baby is so far outside the box!

Well done sir!

Tom

MJP · « **Reply #223 on:** July 19, 2017, 05:12:13 PM »

Thanks Bob for doing the math, we will have more data on helium next week Monday or Tuesday.

Well Tom, its been a long time comming and now that I made the new valve substituting the dumb valve.
It started to get interesting again and I can't really stop working on it to be honest.
I want to see what can be had with this platform on air and then the absolute maximum on helium.

I'll cast more ammo this week and will skip all the light stuff, well if you can call 108 gram light

140-158 grams, or if I can extend the mold just a tiny bit and get to around 170 gram.

The 140g has a calculated g1 bc around .711 measured from 0-100m the holdover was a lot less than I expected for 300m and shot over the berm in to the trees. Did make lot of noice in the forest.

Marko

MJP · « **Reply #224 on:** July 20, 2017, 10:29:46 AM »

Long hours in the shop, couple of picatiny rails done and extra hammer weight, plus remote housing for the chrony display and electronics.

Marko

TPL · « **Reply #225 on:** July 20, 2017, 10:42:46 AM »

Next week will going to be very interesting.

MJP · « **Reply #226 on:** July 20, 2017, 02:29:39 PM »

Yes indeed. Lets see what are the final numbers on air. I'm really hoping the extra 45g of hammer mass will help opening the valve at 300bar.
I will cast some bullets tomorrow after I have turned a barrel for Eve.

Marko

urgthrash · « **Reply #227 on:** July 21, 2017, 03:19:10 PM »

Just freakin wow...

Lotta luv in that project

MJP · « **Reply #228 on:** July 21, 2017, 04:20:02 PM »

Thanks Tom.
I have had some spare time so I try to make the best of it.

Marko

QVTom · « **Reply #229 on:** July 21, 2017, 05:55:43 PM »

Marko, I love the way you executed your receiver by taking the design well beyond the typical tube gun

Tom

MJP · « **Reply #230 on:** July 22, 2017, 04:38:41 AM »

Thank you Tom,
Something like that comming from a manufacturer of one of the finest american rifles. It means a lot.

Its the first thing I really was thinking about a lot, the forces are so great that I wanted the extra safety of 6 locking lugs.
Its built more likea powder reciver than an airgun really. There is no separate transfer port between the lower and reciver, only a 2mm thick alu sealing ring.

Marko

MJP · « **Reply #231 on:** July 22, 2017, 04:55:50 PM »

Getting ready for another range session, casting bullets from light(ish) 146 to heavy 174gram. Ammo starting to look like mortars.

Did make another barrel for a the good old trusty .357 this time in .311 and my girl Eve can test it out.
What a better way of ending the week, reloading brass and casting ammo to spend it again next week

Marko

MJP · « **Reply #232 on:** July 23, 2017, 03:56:46 PM »

And some perspective on the size of the rifle, found a suitable scope that doesn't look too small.
It looks pretty big, about as long as I am.

Marko

Rob M · « **Reply #233 on:** July 23, 2017, 04:15:18 PM »

HOLY COW , its about double the size I imagined, unless of course you are 3 feet tall

MJP · « **Reply #234 on:** July 23, 2017, 05:00:49 PM »

The barrel is 1.1 meters long so adding the reciver and stock it became pretty darn long.
But it's built purely for fun. Its not going to be a hunting rig of any sorts.

Marko

Allen A · « **Reply #235 on:** July 23, 2017, 05:15:13 PM »

Wow...now that's a gun! Excellent build Marko.

rsterne · « **Reply #236 on:** July 23, 2017, 05:21:03 PM »

Love that shot, Marko.... really lets us appreciate how BIG this build is....

Bob

michaelthomas · « **Reply #237 on:** July 23, 2017, 05:27:39 PM »

Holy Cow...I had no idea of the size of that thing from the other pics! That's awesome!

Mike

Finn · « **Reply #238 on:** July 23, 2017, 07:20:23 PM »

Suksethan tuo vielä tarvii

rifle50 · « **Reply #239 on:** July 24, 2017, 12:15:24 AM »

Quote from: MJP on July 23, 2017, 03:56:46 PM

And some perspective on the size of the rifle, found a suitable scope that doesn't look too small.
It looks pretty big, about as long as I am.

Marko

Thanks Marko for the PERSPECTIVE PHOTO............WOW is about all I can say............Great Work.

Carl

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Project Fury 20mm BIGbore. 3100FPE!

Author Topic: Project Fury 20mm BIGbore. 3100FPE! (Read 86467 times - 2 votes) )

Author Topic: Project Fury 20mm BIGbore. 3100FPE! (Read 86467 times - 2 votes)
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