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Latke Data Collapse... The Plot Thickens

Posted: Mon Apr 14, 2008 2:26 am
by D_Hall
OK, so we've spent a few days arguing over the long-barrel velocity collapse exhibited by the Latke L2 1.5" shooting spuds. I've spent a lot of time studying that scenario. Why THAT scenario? I dunno, I just grabbed it and ran with it.

Anywho, after much wracking of brains here's the best that I came up with....

Image

...Disgusted with my inability to model the much discussed knee in the curve I decided to just move on and come back to it at a later time. I finished up some bits and pieces of HGDT and even went to work on the webpage.

Working on the webpage I felt that I needed to compare HGDT to *something* so I revisited Latke. Yeah, the spud has already been talked about. Given how badly I was modelng the spud I was scared to see what would happen if I modeled anything else.

Long story short: I threw HGDT up against the Latke L2 shooting wood data.

WTF?......

Image

....While I love that HGDT is riding the Latke data pretty well... Where did the knee go?


ARGGGGHHH!

Project for immediate future: Look at the rest of Latke's data. Is the knee endemic to the spud data, but not the wood data? If so, why? Blah blah blah.

Posted: Mon Apr 14, 2008 2:41 am
by starman
Hummm interesting. Maybeeeee the spud seals the barrel and the wooden slug doesn't....... or... moisture in the spud vs not in the slug.... or.... wooden slug is a smaller caliber....

Just thinkin' out loud here....

Posted: Mon Apr 14, 2008 6:17 am
by psycix
Maybe you should perform tests on your own.
That way you can measure anything you want and will have accurate data to work with.

I cant see why the wood doesnt knee
Weird it is.....
Maybe the wood knee has fallen off the graph since the wood tends to go faster


EDIT:
ARGGGGHHH!
AAAAAAAAAAAAAAAAAAAAAAARGH! :evil:

lol :D

Use facepalmdeaddeskcombo?

Posted: Mon Apr 14, 2008 7:21 am
by JDP12
interesting results... i'm with physix on doing your own testing

Posted: Mon Apr 14, 2008 1:44 pm
by jimmy101
I believe Latke breech loaded his spuds. Perhaps blowing a spud down a many foot long barrel abraided the spud and dropped the friction and/or created blow-by? In other words, a long barrel acts funny with fragile ammo like a spud?

BTW, my combustion model also has trouble with the"knee".

Posted: Mon Apr 14, 2008 5:32 pm
by SpudMonster
psycix wrote:Maybe you should perform tests on your own.
That way you can measure anything you want and will have accurate data to work with.

I cant see why the wood doesnt knee
Weird it is.....
Maybe the wood knee has fallen off the graph since the wood tends to go faster


EDIT:
ARGGGGHHH!
AAAAAAAAAAAAAAAAAAAAAAARGH! :evil:

lol :D

Use facepalmdeaddeskcombo?
Hmm. That could be the case. The wooden slugs have less friction and weigh more, so they could wind up coasting past the knee. Or as has been stated before, the spuds could be abrading.

Posted: Tue Apr 15, 2008 4:41 pm
by clide
Those wooden slugs have gaskets on the back don't they? The gaskets could be acting like a check valve. No blow-by when the pressure on the chamber side is higher than the muzzle side, but once the pressures are reversed the gasket is able to flop backwards and allow blow-by and reduce friction.

Of course the bad thing with that theory is that the knee still exists for a normal gun, but the projectile design is preventing it.

Does the knee show up on the tennis ball data as well?