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Old 4th October 2013, 07:30 AM
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Brian.Samson Brian.Samson is offline
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Join Date: Jun 2009
Member of: Pontefract, Doncaster Airgun Range
Location: Doncaster
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Originally Posted by sven View Post
From what I have read here and there in ballistics books it is NOT the Time to target that is the main factor. It is the retardation of the projectile (retardation in feet per second per second, fps/s or ms/s).

A pellet that slows down more during flight suffers a greater wind effect. Even when the total time to target is the same because the pellet has a higher muzzle velocity it is still the one that slows down the most that has the largest deviation due to the wind.
Hmm.. that might actually be taken account of in the standard wind drift calculation thinking about it.

The time that's important, is the difference in time between the flight in air and the flight in a vacuum.

The time of flight in a vacuum is dead easy to calculate because the pellet leaves the barrel at it's muzzle velocity, and then doesn't slow down at all - it just carries on at the muzzle velocity for the whole flight.

Supposing you've got two pellets - one with a high BC and one with a low BC and you shot the one with a low BC at a higher muzzle velocity such that the two pellets reach 55 yards in the same time. The speed in a vacuum of the low BC pellet would be less than the time in flight of the high BC pellet. So you'd be taking away a smaller amount of time from the low BC (more draggy pellet) in the equation and the wind drift would be greater.

Yup, I think you're right!.. And that is modelled by the standard drift calculation. Perhaps thats the reason the time of flight in a vacuum is important then??
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