oh man... where to start

oh man... where to start

Joined: March 1st, 2002, 12:22 am

June 25th, 2012, 7:19 pm #1


Thanx guys for all the responses to my post below (http://www.network54.com/Forum/275684/t ... +the+P+Rod....)

I leave you  alone for a couple days, and the brain trust goes wild with a lot of great info and suggestions. Now to sort thru it all....

A lot of talk about changing, or not, the TP from its .101 to possibly something closer to factory diameter..... split the difference? (hehe what we need here is an externally adjustable TP with an iris type "shutter" to be able to test the various theories discsussed sans disassembly... )

Scott was the only one to mention fill pressure. Is that an area needs exploration?  Try the same settings across a number of fill pressures and see what happens?

Was thinking of doing just that... run both adjustment back to "zero"(and counter striker preload to verify my count was corect from last week), then a mag over the chrony to see what happens. Study that for a moment, then make another adjustment and retest? Only test one setting (say striker preload first, then hammer throw)?  set both to the "mid range" and work it either way?

Does all this go straight into the trash heap when I change pellet weights? ( I suppose after this thing settles in, and I find what thing likes to eat, that I should buy a few tonnes of them....)

So I thinkI'll start with:

No change to anything: 5 shots each at 2400, 2600, 2800, 3000. record and plot. Baseline in its current state

run both adjsutments to "zero" and rerun the fill spread test, record and plot

run one adjsutment (striker preload most likely) to the 1/2 point, run the fill spread test, record and plot

dont change the adjustment made above, but start moving the other, record results across the fill spread

I would think that by the third set of tests that some indication or pattern would begin to develop, and suggest a further course of action.

At this point, I open the floor to discussion......

 

 

 

 

 


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
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Joined: August 20th, 2008, 3:27 pm

June 25th, 2012, 11:46 pm #2

Dan if you don't mind me asking, what kind of a tune are you looking for ? highest energy & lower shot count or longest flatest low energy tune?
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Joined: November 17th, 2006, 3:51 am

June 26th, 2012, 1:45 am #3

Thanx guys for all the responses to my post below (http://www.network54.com/Forum/275684/t ... +the+P+Rod....)

I leave you  alone for a couple days, and the brain trust goes wild with a lot of great info and suggestions. Now to sort thru it all....

A lot of talk about changing, or not, the TP from its .101 to possibly something closer to factory diameter..... split the difference? (hehe what we need here is an externally adjustable TP with an iris type "shutter" to be able to test the various theories discsussed sans disassembly... )

Scott was the only one to mention fill pressure. Is that an area needs exploration?  Try the same settings across a number of fill pressures and see what happens?

Was thinking of doing just that... run both adjustment back to "zero"(and counter striker preload to verify my count was corect from last week), then a mag over the chrony to see what happens. Study that for a moment, then make another adjustment and retest? Only test one setting (say striker preload first, then hammer throw)?  set both to the "mid range" and work it either way?

Does all this go straight into the trash heap when I change pellet weights? ( I suppose after this thing settles in, and I find what thing likes to eat, that I should buy a few tonnes of them....)

So I thinkI'll start with:

No change to anything: 5 shots each at 2400, 2600, 2800, 3000. record and plot. Baseline in its current state

run both adjsutments to "zero" and rerun the fill spread test, record and plot

run one adjsutment (striker preload most likely) to the 1/2 point, run the fill spread test, record and plot

dont change the adjustment made above, but start moving the other, record results across the fill spread

I would think that by the third set of tests that some indication or pattern would begin to develop, and suggest a further course of action.

At this point, I open the floor to discussion......

 

 

 

 

 


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
So far, playing with carbines of limited air volume and NO valve mods:

1. The harder you smack the valve, the higher the sweet spot pressure. Are several ways to get that harder "smack"...stronger spring, heavier striker, longer stroke.
2. A more or less direct proportion between sweet spot pressure and energy.
3. SHOT COUNT doesn't change much; more energetic with pressure increase, but the number of shots within the same limit (set FPS or percentage of max) remains about the same.

What I think happens with #3 is that sooner or later, if you can get the operating pressure up high enough, the transfer port ev entually resticts....which limits air use, makes energy rise LESS than proportional to pressure rise, and extends the shot count. But if you have it "wide open" are likely to run into tube limits before that happens.
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Joined: March 1st, 2002, 12:22 am

June 26th, 2012, 5:02 am #4

Dan if you don't mind me asking, what kind of a tune are you looking for ? highest energy & lower shot count or longest flatest low energy tune?
at something oh 725ish fps

it was doing 670 stock, for 3 mags

And Im very much willing to trade speed for consistancy, to a point.

I think its in there, just a matter of finding it.

 


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the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
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Joined: March 1st, 2002, 12:22 am

June 26th, 2012, 5:16 am #5

So far, playing with carbines of limited air volume and NO valve mods:

1. The harder you smack the valve, the higher the sweet spot pressure. Are several ways to get that harder "smack"...stronger spring, heavier striker, longer stroke.
2. A more or less direct proportion between sweet spot pressure and energy.
3. SHOT COUNT doesn't change much; more energetic with pressure increase, but the number of shots within the same limit (set FPS or percentage of max) remains about the same.

What I think happens with #3 is that sooner or later, if you can get the operating pressure up high enough, the transfer port ev entually resticts....which limits air use, makes energy rise LESS than proportional to pressure rise, and extends the shot count. But if you have it "wide open" are likely to run into tube limits before that happens.
Like what we do on the 13xx/22xx valves?

Do that now, or wait till the consistent FPS gets dialed in?

 

 


dr_subsonic's pneumatic research lab

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Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
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Joined: January 16th, 2011, 9:27 pm

June 26th, 2012, 6:13 am #6

at something oh 725ish fps

it was doing 670 stock, for 3 mags

And Im very much willing to trade speed for consistancy, to a point.

I think its in there, just a matter of finding it.

 


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
I just looked back through my tuning notes for my p-rod and found a string right around what you are looking for.

CPHP 14.3 gr 24 shots 712-730-712 from 2800 psi down to 2000 psi

If you can push the sweet spot a little higher you could get even better results.
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Joined: November 17th, 2006, 3:51 am

June 26th, 2012, 11:00 am #7

Like what we do on the 13xx/22xx valves?

Do that now, or wait till the consistent FPS gets dialed in?

 

 


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
...do it before getting into final testing. Becasue the valve is so basic to the system, cahning aspects of it (volume/valve stem size, valve stem weight,etc) that everything else changes.
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Joined: March 1st, 2002, 12:22 am

June 26th, 2012, 7:10 pm #8


return spring, valve "head" shapes, easing the airpath, etc?

Ok, into the gun tonight

 

edit: speelng, wot elz?
dr_subsonic's pneumatic research lab
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the Lunatic Fringe of American Airgunning
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Proud Sponsor of team_subsonic
Last edited by dan_house on June 26th, 2012, 7:11 pm, edited 1 time in total.
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