T = (K * D2) / L
Posted: Tue Feb 05, 2013 9:52 pm
T = (K * D2) / L
Discuss
Discuss
Blu
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T = (K * D2) / L
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Re: T = (K * D2) / L
Posted: Tue Feb 05, 2013 10:03 pm
Busy here, I'm out twice a day keeping trails and a long driveway clear of snow. I also plough a trail and driveway for an elderly neighbour lady who's a bit too old for moving snow around so she can take her pups out as well.
Blu
Blu
Re: T = (K * D2) / L
Posted: Tue Feb 05, 2013 10:05 pm
Greenhill?
Re: T = (K * D2) / L
Posted: Tue Feb 05, 2013 10:26 pm
WHOOOOOOOOOOOSH !!
and I didn't even have to duck
and I didn't even have to duck
Re: T = (K * D2) / L
Posted: Tue Feb 05, 2013 10:40 pm
Alfred George Greenhill, 1847-1927...
Calculation of optimal twist rate for a lead core bullet with a copper jacket?
T = rifling twist in inches
K = a constant = 150 Greenhill (for muzzle velocity of 457 to 853m/s), 180 - for the muzzle velocity of over 853m/s and 125 - for pistols. (Or whatever these values are for muzzle velocity converted to fps)
These constant values are valid for lead core bullets with a jacket made of copper or brass.
D = bullet diameter in inches
L = length of the bullet in inches
I'm sure ovenpaa will probably enlighten us further.
Calculation of optimal twist rate for a lead core bullet with a copper jacket?
T = rifling twist in inches
K = a constant = 150 Greenhill (for muzzle velocity of 457 to 853m/s), 180 - for the muzzle velocity of over 853m/s and 125 - for pistols. (Or whatever these values are for muzzle velocity converted to fps)
These constant values are valid for lead core bullets with a jacket made of copper or brass.
D = bullet diameter in inches
L = length of the bullet in inches
I'm sure ovenpaa will probably enlighten us further.
Re: T = (K * D2) / L
Posted: Tue Feb 05, 2013 10:41 pm
So it would seem.ovenpaa wrote:Greenhill?
Where by
T = pitch of 1 revolution
D = projectile diameter
L = projectile length
K = Greenhill Constant
Isn't Google brilliant.
D'oh, beaten to it
Re: T = (K * D2) / L
Posted: Tue Feb 05, 2013 10:55 pm
I cannot really add to what has been said other than I recognised it. I can still quote obscure mathematical formulae from nearly four decades ago, last used in exams in 1975...
I remember things only if they interest me.
I remember things only if they interest me.
Re: T = (K * D2) / L
Posted: Tue Feb 05, 2013 11:20 pm
Couldn't have put it better myself...pe4king wrote:WHOOOOOOOOOOOSH !!
and I didn't even have to duck
Re: T = (K * D2) / L
Posted: Tue Feb 05, 2013 11:34 pm
Re: T = (K * D2) / L
Posted: Wed Feb 06, 2013 7:56 am
Wrong, but occasonally useful.John25 wrote:T = (K * D2) / L
Discuss
Gaz