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Old 2nd October 2013, 09:58 PM
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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
Posts: 2,328

Originally Posted by rich View Post
It's a pity Doncaster is so far away from here, Brian, we could lend you a 42 yard wind free tunnel for your investigations.

For a very long time I've felt that the ballistic models we accept as given are not the full story. Nailing down what the differences are, and what causes them, will be worth a Hon Ph.D. for somebody.
Haha, Rich I've had that conversation with people in the past and the reaction you get is as though you've committed some sort of act of heresy - It's maths, it can't be wrong!

Now I'm not a ballistics expert by any stretch of the imagination, but I have been a programmer every day of my working life for the past 25 years and I've got the trajectory calculation source code used by all of the main ballistics calculators and I can see some scope for inaccuracies in there.

Mainly centred around BC and the drag retardation tables used to adjust BC for different velocity bands.

The calculations we use are an approximation with some adjustments from real world data. But they're all based on projectiles at significantly higher velocities, and in flight stability being provided in a different manner. I'm not convinced Chairgun's 'GA' profile isn't just a made up table either. (I found that it gives almost the same answer as the G1 profile with a 7% reduction in drag across the board).

So yes, I also believe they don't give you the full picture. ( I'll probably be burned at the stake for suggesting such a thing though )

There's a chance I might be able to get access to a 50m indoor range... I don't think clamping my TX in a vice is going to help my groups I can probably borrow something a bit special for some testing though if I can arrange access.
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