Author Topic: XS60C PCP Repeater project (Read 455905 times))

stalwart · « **Reply #920 on:** February 17, 2015, 01:55:27 AM »

Quote from: rsterne on February 16, 2015, 10:25:31 PM

I think stalwart has an alternative stock mount planned so that he doesn't drill the tube at the bottom between the O-rings.... One of the little things that prototyping teaches you....

I do. For the tankers, I'll be making a very similar set up (unsealed, of course), for the block. It will be shouldered, and act as a back up, as well as take the standard 5mm for stock mounting. I can't think of an easier option... and always try to avoid custom or rare hardware, when quality can be maintained... but the tanks give me no apparent options. Extended double tube set ups will use this, as a R tube mount. Single tubes will simply have a 3rd screw installed in that identical hole. This only generates 1 more part#, to cover all options in reservoirs.

I ordered a complete assortment of the screws, in bulk, of as high a grade as they sell. I'll be including full kits with any rifles done from now on. This included the 6mm long trigger group mount screws to allow stroking (recessing the F mount nut), without taking that mm or so off the end of a stocker, for clearance.

What are our options in a larger dia lower tube? I keep thinking that a fat 4.5K lower, with an inline reg to 3K max supplying the full length plenum, would really make these breath. A long time ago, I came across a thread discussing inlines... what's state of the art now?

rsterne · « **Reply #921 on:** February 17, 2015, 02:29:23 AM »

No idea, I'm not a fan of inline regulators, because of the plenum problem for any kind of real power.... Once you talk about running one reservoir, then a regulator, feeding a large plenum, you're talking my language.... The simplest way is to use the piston from a Ninja regulator and build a housing for it.... it can be in one of the tubes, or in the vertical portion of my tank block, take your pick.... As far as the commercially available inline regs., I know nothing about them....

If you use a lower tube that is larger than the upper, inletting the stock becomes problematic.... and in fact housing both tubes IN a stock ultimately becomes an issue.... Fat 4.5K tubes require significant engineering for the end caps.... and pretty soon you're looking at Titanium for the tube to save weight as they get heavy in a hurry.... I can't help but wonder how far it makes sense to go in that direction.... I becomes a matter of clearly defining a goal first, IMO.... for you, a marketable and profitable one....

Bob

Gertrude · « **Reply #922 on:** February 17, 2015, 02:32:03 AM »

I'm just in awe trying to follow and keep up with what you guys are doing in this thread.
I keep telling myself that one of these days, I'm going to need to go back and read it all over from the beginning. Then I'll try to pick and choose what level I may eventually want to take mine to... but with the constant development you guys are doing, I keep waiting for the "end goal" to come.
I think this thread needs to get re-named as a parody to the movie "How to Train Your Dragon (part 10)" LOL!

Keep up the fantastic work guys !

stalwart · « **Reply #923 on:** February 17, 2015, 03:05:04 AM »

Quote from: tri-5-ron on February 17, 2015, 02:32:03 AM

Keep up the fantastic work guys !

Thanks! Bet on it, Ron.

Quote from: rsterne on February 17, 2015, 02:29:23 AM

No idea, I'm not a fan of inline regulators, because of the plenum problem for any kind of real power.... Once you talk about running one reservoir, then a regulator, feeding a large plenum, you're talking my language.... The simplest way is to use the piston from a Ninja regulator and build a housing for it.... it can be in one of the tubes, or in the vertical portion of my tank block, take your pick.... As far as the commercially available inline regs., I know nothing about them....

If you use a lower tube that is larger than the upper, inletting the stock becomes problematic.... and in fact housing both tubes IN a stock ultimately becomes an issue.... Fat 4.5K tubes require significant engineering for the end caps.... and pretty soon you're looking at Titanium for the tube to save weight as they get heavy in a hurry.... I can't help but wonder how far it makes sense to go in that direction.... I becomes a matter of clearly defining a goal first, IMO.... for you, a marketable and profitable one....

Bob

The stock is no problem. A lot more familiar area for me. I've worked out a design I think you'll really like.

As you have known for a long time, a true .22LR equivalent was my goal all along (they'll sell here, close=no cigar.), and I want to go 9mm for the next step. I think a big double is the way to go. Hanging that tank, reversed, at the end of a longer plenum is not an option. It would finish off the damage we have already done to the gun's (beloved, at least here) balance.

It's gotta happen, Bob.

Kailua · « **Reply #924 on:** February 17, 2015, 03:51:10 AM »

What if you were to combine the double tube with the tank? So there would be two shorter tubes stacked with a three way connection. Like a wye connection. Having the regulator and tank in front of the double tubes. This way the tank can sit higher and would be able to fit a stock. Or would there to much restriction of flow from one tube to the other? Anyways its just a thought.

stalwart · « **Reply #925 on:** February 17, 2015, 04:54:57 AM »

It's good thinking. Anything to pull some weight back. Bob can answer best, but I believe the transfer wye would have to be pretty large, to act as a plenum. Be nice if it doesn't! I'd love to get a look at Xisico's double tube (side by side) 60, apart.

I'm thinking of extending the lower tube all the way back to the block screw, and mounting it there. A 27" steel tube, 7/8" dia, weighs 3oz more than a bare 22ci tank. Figure in internal reg vs. reverse block... 1" tube (1-1/4?)... and it should be, at least somewhat, better balanced and better protected (reg). We're not done yet!

stalwart · « **Reply #926 on:** February 17, 2015, 07:51:59 AM »

Made this a while back... turns nickle plated grommets into a nice way to keep screws from digging into the stock.

Every hardware kit will get one of these.

stalwart · « **Reply #927 on:** February 17, 2015, 09:07:33 AM »

Just looked into titanium tube... Will the same dimensions work with the pressures?

StevenG · « **Reply #928 on:** February 17, 2015, 09:10:45 AM »

.22LR replacement? As in 100ftlbs for the subsonics?

stalwart · « **Reply #929 on:** February 17, 2015, 09:23:31 AM »

Yup.

Bob figures 118 with a 7/8" double @ 3K, with no other changes. A full mag.

RHytonen · « **Reply #930 on:** February 17, 2015, 10:26:19 AM »

I've got it covered, with the Windowsill Cannon's (and its tube's) extreme length - thus standard (7/8") OD throughtube receiver, plugs etc.

Now I'm just concerned with adding enough valve dwell to fill half that long barrel, without having it too hard to cock (hence the PEEK musing.)

Rod

RHytonen · « **Reply #931 on:** February 17, 2015, 10:34:05 AM »

Quote from: rsterne on February 17, 2015, 01:46:24 AM

PEEK is .... more difficult to get to seal....

Bob

Wouldn't lapping it fix that?

Rod

RHytonen · « **Reply #932 on:** February 17, 2015, 10:44:56 AM »

BTW - has anyone sourced a 4K3(-5) psi 2" bottle yet?

stalwart, I'm also wondering what is the difference between a 3K and a 4.5K throughtube...
(and no answering, "1.5K..."

Rod

stalwart · « **Reply #933 on:** February 17, 2015, 11:16:42 AM »

ChroMoly tube, (3) 1/4"-28 backing screws. Everything else the same... Production 3Ks will probably just be 4.5Ks too. Less part #s.

rsterne · « **Reply #934 on:** February 17, 2015, 01:19:30 PM »

Don't forget, the pellet doesn't spend much time going from the 12" point to the 20" point in a (40") barrel, so the increase in the required dwell is no where near in proportion to the barrel length increase.... In fact, according to Lloyd's spreadsheet, if you put a 40" barrel on my Grizzly, with no change in dwell, those 70 gr. BBT's would move up from 840 fps to 934 fps (136 FPE).... NO OTHER CHANGES EXCEPT BARREL LENGTH.... Increasing the dwell to the 50% point of that 40" barrel should give 980 fps (150 FPE), and that only requires a 30% increase in dwell.... I can already achieve more dwell than that with my existing hammer and spring....

I think you could make a decent 9mm by using a full length upper tube as a plenum at 3K, regardless of how you feed it to give it more volume.... regulated or not.... 28" barrel would help the numbers....

Bob

rsterne · « **Reply #935 on:** February 17, 2015, 08:51:16 PM »

Well pulling the gun apart to chase leaks was worth it.... For the most part I've found them, although I still have one slight puff of air that I think is mostly blow-by from the valve stem.... When I fitted the MRod poppet it was a little loose.... Anyway, I got the gun back together and duplicated yesterday's tests, and there isn't enough difference to even bother changing the graph.... I picked up a few fps per shot on the 45 gr. JSBs, so the efficiency is about 1% better, although I did make a mistake on the ending pressure on the original string with the Daystates, that 1960 psi was after 17 shots, not the full 18, so the efficiency on that string is 1.01 FPE/CI.... I'm actually quite surprised how little difference getting rid of the leaks made to the numbers.... I did gain about 15 fps with all three pellets when I maxed the hammer preload, so the plateau is no longer quite flat, and that was consistent over all the weights.... I'm not sure why that is, but it doesn't matter anyway, because you can't run that much dwell, you are just wasting huge amounts of air.... The interesting thing is that once you tune back to the knee of the curve, the velocity gain with the leaks fixed was only about 5 fps or so.... No idea why the leaks are more siginificant when you are pouring huge amounts of air through the gun, but it is what it is....

I plan to make the barrel band tomorrow.... Oh, I did one other test today, I tried the Daystate 50 gr. pellets with another 1/2 turn of preload.... I gained 20 fps (up from 923 to 943 average), to give me an average of 98 FPE, but lost 5 shots (18 down to 13), and the efficiency dropped from 1.01 FPE/CI down to just 0.82 FPE/CI.... You can sure see how critical it is for efficiency not to run too much hammer strike on a regulated PCP.... I might try a setting in between, that should yield about 96 FPE for 15 shots, with an efficiency of about 0.90 FPE/CI, which I could live with.... The final settings and pellet choice will depend on accuracy, of course.... Accuracy testing will have to wait until the snow around here melts and I can get out to my test range....

Bob

rsterne · « **Reply #936 on:** February 17, 2015, 11:29:11 PM »

Here is the finished result....

This has been a really fun and satisfying project, from conception nearly a year ago to being able to shoot it this week.... I'm delighted with the way it turned out....

Bob

stalwart · « **Reply #937 on:** February 17, 2015, 11:50:02 PM »

Me too...

What's next for it? Gonna get fancy with the finish?

Kailua · « **Reply #938 on:** February 18, 2015, 12:37:16 AM »

Thanks for taking the time to share every step of the process. Now I'm just waiting on Eric.

stalwart · « **Reply #939 on:** February 18, 2015, 12:57:37 AM »

Quote from: Kailua on February 18, 2015, 12:37:16 AM

Thanks for taking the time to share every step of the process. Now I'm just waiting on Eric.

Tick... tock...

I haven't been taking deposits on new work, as I'm kinda buried in non-AG matters right now... and slowly moving SA into a bigger space.

This doesn't mean we can't start planning something... email me with your thoughts. I'm making progress here... there's a light at the end of the tunnel, I'm just hoping it isn't an oncoming headlight.

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XS60C PCP Repeater project

Author Topic: XS60C PCP Repeater project (Read 455905 times))