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Old 3rd October 2013, 09:44 AM
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Brian.Samson Brian.Samson is offline
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Member of: Pontefract, Doncaster Airgun Range
Location: Doncaster
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Originally Posted by neilL View Post
Once airborne the pellet is subjected to a lateral force aka wind (no wind, no force) for the duration of the flight time. The force depends on profile, wind speed and direction
Yup, all the rest looks ok, apart from the quoted line - that's not correct. Very odd I know, but the wind drift doesn't depend on side profile (according to ballistic theory). Unless that side profile has an effect on total time to target - i.e. the different profile causes more drag.

It took me a while to get my head around this when I started flying microlight aircraft, but it's the same thing.

When you're plotting the wind drift vector for an aircraft, how aerodynamic the aircraft is from it's side profile makes no difference whatsoever to the wind drift.

The reason is - the wind applies no sideways force to the aircraft, because the aircraft once airborne is a part of the atmosphere - so it's moving forwards through a substance (the air) that just happens to be moving sideways.

Well that's how it's been explained to me, any documents you read about wind drift for projectiles will tell you exactly the same thing and the calculation used in things like Chairgun (which just use a standard wind drift calculation) take no account of the side profile of a pellet.

It doesn't 'feel' right to me, but that's the accepted theory and has been for hundreds of years.
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