location of flash hole

[yip]

  what are the limits to the flash hole location? center of the pan is okay ,but a little high. is this tolerable?

[Stuartg]

What do you mean by a little high? Do you have any pics? I know there's been a lot of research done on this topic, and from what I can recall a little high is better then a little low.

[Acer Saccharum]

I've had a touch hole covered halfway with the pan cover when closed. No apparent problems.


Look up the high speed photography research Larry Pletcher has done on flint ignition, should be posted on his Black Powder Mag site. http://www.blackpowdermag.com/  He busted a lot of myths.

You will also find interviews of totally famous builders like Allen Martin, and horners like Art DeCamp, historians like the late Gary Brumfield.

[WadePatton]

...Look up the high speed photography research Larry Pletcher has done on flint ignition, should be posted on his Black Powder Mag site. http://www.blackpowdermag.com/  He busted a lot of myths.

...

Which leads me to think i might poke the next one a little lower.

[galamb]

In the Gunsmith of Grenville County, Peter suggests that you place the flash hole 1/16" "below" the midpoint of the side flat.

[smart dog]

Hi Yip,
Larry Pletcher's wonderful photography revealed that the powder charge is ignited by radiant heat from the priming, not actual flame.  Radiant heat is at its maximum when the largest volume of priming is burning.  A touch hole level with the top of the pan takes advantage of the top layer of burning priming powder and should produce faster ignition.  However, the amount of radiant heat entering the barrel is less than after more priming burns.  My experience suggests to me that for thinner walled barrels, a higher touch hole (level with top of the pan) works very well but as the barrel thickness increases I believe more radiant heat is needed to ignite the charge, particularly after fouling starts to pack around the touch hole or in the liner if you have one.  On bigger barrels, I either move the touch hole down lower in the pan (about half way) or drill the touch hole bigger.  That strategy seems to work pretty well so far for me.

dave

[Joe S]

A touch hole level with the top of the pan takes advantage of the top layer of burning priming powder and should produce faster ignition.

If you look at all of Pletcher’s data, you will find that there is no difference in ignition speed when a hole at the top of the pan and the bottom of the pan are compared.  These data are for one shot with a clean flash hole.  Other data suggest you get the best flame front moving into the barrel with the flash hole at the very bottom of the pan.  Arguments against placing the hole at the very bottom are the increased difficulty of picking the flash hole and potentially increased erosion of the pan.

I'm going to be drilling a flash hole in the near future.  Balancing all the available data, I think the optimal placement is probably midway between the top and bottom of the pan.  This takes advantage of an improved flame front and allows for easy cleaning of the flash hole.  An improved flame front is apparently of no consequence with a clean flash hole, but under field conditions, it could plausibly be of service.

[rich pierce]

Pan erosion on original locks suggests that touchholes were sometimes low in the pan.

[Larry Pletcher]

Pan erosion on original locks suggests that touchholes were sometimes low in the pan.

Rich,
This idea was what got the vent experiment going.  I was sitting in Mark Silver's booth at friendship talking with him and Gary Brumfield.  Gary surprised us when he said that he and Wallace had examined a number of original foreign guns with very low vents. My thought was that I can test that.  We discussed how the experiment should be set up, and we went from there.

Regards,
Pletch

[Joe S]

Pletch

Would it be possible for you to post all of your studies in a single place?  They can be pretty hard to find.  Maybe on this site under Tutorials?

[Acer Saccharum]

Joe, the tests ARE in one place. See the link I pasted above.

[Larry Pletcher]

Tom is right.  Use the following link:http://www.blackpowdermag.com/
Click on the black bar to the right of "Home" and you get a pop-up Table of contents. From there you can see everything. The photos that circulate just below are lead-ins to the last four articles posted.

Below that are sections separated by topics, but everything is there. I have to add that a year ago the site was a mess.  The navigation was old fashioned with many corrupted files and audio that did not function at all. BY June Friendship, my son worked a bunch of magic, and the site is much more attractive, navigation is a snap, and will work on tablets, smart phones, etc. He also insisted on a blackpowdermag facebook page which I am supposed to keep up to date. I also update posts on the NMLRA facebook page.

Regards,
Pletch

[Joe S]

Thanks for the link gents.  Pletch – the website is much improved.  I guess it’s been a while since I looked for some of your data.  It used to be a bit of a chore to find things, but now it’s all accessible.   

[kaintuck]

Holy flash hole batman!

Sunset to pan works for me, the book "recreating the American longrifle" has a good chapter on placements......

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Marc n tomtom

[flehto]

Have been locating the center of the  TH in the White Lightnings even w/ the pan top or slightly above. The ignition is so quick that I sometimes think the WL is taking all the fun out of shooting flintlocks.

Don't think that when using a WL TH liner, the TH location is that critical.....perhaps it is w/ just a drilled hole. ...especially w/ thicker walled bbls.

Haven't located a TH in a WL liner near the pan bottom, but suspect that the ignition  will be just as quick......Fred

[ironwolf]

  I gotta agree with Flehto on the WL liners.  If fitted correctly, you wind up with the equivalent of a wall thickness around .060 to .070 inches.  The powder charge is right there.  So close that they can be fired with no prime at all.

   Kevin

[yip]

  did so measuring, 1/32 above the top of pan,but centered left to right. hope this clears things up, used a 1/4" whitelighting can go to the larger one if i gotta. ..............yip