Project Fury 20mm BIGbore. 3100FPE!

[MJP]

Finally had time to engrave the name on the frame.
Turned out ok, should have made it more ragged looking, but its fine.

Tomorrow final assembly and hopefully it holds air.

Marko

[Motorhead]

Pre-NATO tank killer

[MJP]

Yep,
Need to upgrade it to be Nato compatible 

Marko

[MJP]

And when you forget the buckling factor...
if it was easy everyone would be making these.

Valve connecting rod, calculated failure point 556kg compression, let go at 570kg about.
We sometimes forget something, and failure is a learning experience.

Marko

[rsterne]

Excellent learning experience for all of us.... Thanks for posting that as a reminder.... 

Bob

[sb327]

Failure is a learning experience!

And I am constantly learning!

Dave

[lefteyeshot]

You all still talking about this Oerlikon.

[MJP]

Yes...

So I have come to the point in valve sizes and forces that plastic is no longer a viable option.
So we turn the next one from steel and titanium.

PEEK valve poppet pulled in half from the balancing force.

Interestingly the cut follows the thread pitch line all the way to the outside.
Valve size is large.

Marko

[JuryRigger]

Almost like the crest of the thread acted as a stress riser?
Dayum! 
Jesse

[MJP]

First test and part failure. Doesn't matter we know it works.
200bar air and 3200J of energy. So there is more to be had.
Needs more spring and better material balancer cylinder cage.

Marko

[Rob M]

3200 joules =2360fpe, not too shabby

[MJP]

Its pretty good for 200bar and on the edge of valve lock.
150bar 2100J
180bar 3000J
200bar 3200
And after that no gains and the cage collapsed.
Failure was expected as I didn't have crmo big enough for the cage and made it out of mild steel.
Just so I can verify the new valve dimensions are good.
Failure mode is very predictable and nothing dramatic, gun bleeds out to empty after shot.

Now better cage out of crmo and more hammer spring.
Interesting times ahead.

Marko

[MJP]

New valve parts and a new day...

upload pics
Just some nice looking scenery.
Last time we had a part failure and I used the valve stem from that setup. Should have measured the part first.
Started where we left off last time.
Around 200bar, valve lock and new longer spring.
220bar 139g bullet 233m/s
240bar same bullet 236m/s so again closing  valve lock and started leaking.
Took it apart and stem is bent. Back to the drawing board.
But we are getting to the last power mark with straight air and there is still some 60bar on tap.
Very happy on the performance of the new valve.

Marko

[Rob M]

So 2852 FPE on air !!!!!!!!!!!!! insane ! nice work

[jackssmirkingrevenge]

Fantastic work, it's always great to see dedication to pushing the boundaries!

I also love the "anti-materiel rifle" look, it is somewhat reminiscent of the Steyr HS .50:

[MJP]

Thanks guys,

It's kind of my pet project, can't help it. Just like drag racing, trying to push the boundaries a little.
Need to enlarge the balancer slightly as the cocking force is too high for my liking.
Made and internal ssg as the recoil is starting to get out of hand when there is any hammer bounce on this power levels.

It's working really good, only one sharp report and recoil is snappy.
For now it's manageable but when upping the pressure to the 300bar then it's another story.

Hand getting slightly colored from the recoil.
 
Extrapolating the curve from previous shots we should see north of 5000J on 300bar with air alone.
If not I will be slightly disappointed.


Marko

[MJP]

New sturdier valve stem, 8mm gr5 titanium.

This will hold what ever I throw at it.

Marko

[Rob M]

incredible !@

[jackssmirkingrevenge]

When your valve stem diameter is wider than most air rifle bores, you know it's serious business

[MJP]

When your valve stem diameter is wider than most air rifle bores, you know it's serious business

Now that you put it like that, I didn't think about it before.
It gives a certain perspective to the size.

Marko