Ballistic Co efficient

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Markhamclinton38
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Joined: Fri Jan 13, 2017 7:08 pm

Ballistic Co efficient

Mon Oct 07, 2019 7:40 pm

Does anyone know the Ballistic Co efficient of the Chinese QYS .177 Streamlined 4.5mm 8.48grain Airgun pellets

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gary martin
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Joined: Thu Feb 19, 2015 8:21 pm

Re: Ballistic Co efficient

Mon Oct 07, 2019 8:46 pm

if you use a ballistic software package such as chairgun, you can calculate it by the FPS measured at two points of known distance, or by poi at zero and another known distance. The BC can be different between different barrels etc.

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Markhamclinton38
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Joined: Fri Jan 13, 2017 7:08 pm

Re: Ballistic Co efficient

Mon Oct 07, 2019 9:17 pm

Thank you for your reply. I didn’t realise that the ballistic coefficient was directly linked to a change of velocity between two points on its flight path. Does that mean that the b c changes the further down its flight path it travels?

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tonyc
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Re: Ballistic Co efficient

Mon Oct 07, 2019 10:01 pm

Markhamclinton38 wrote:
Mon Oct 07, 2019 9:17 pm
Does that mean that the b c changes the further down its flight path it travels?
In theory, yes. In practice, at sub-12 airgun velocities you'll not need to worry about this. When using Chairgun you can select a BC profile for the projectile: use one for a similar shaped pellet from the database. You may find you will get different trajectories from different barrels even at the same muzzle velocity. The rifling, choke, and any damage to the pellet will affect the drag, so the BC will be specific to the pellet-barrel combination.

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Markhamclinton38
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Joined: Fri Jan 13, 2017 7:08 pm

Re: Ballistic Co efficient

Tue Oct 08, 2019 10:48 am

Thank you for the information it’s very helpful

Alick

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gary martin
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Joined: Thu Feb 19, 2015 8:21 pm

Re: Ballistic Co efficient

Tue Oct 08, 2019 7:00 pm

https://www.youtube.com/watch?v=H8-m0MGybAA

a video tutorial on how to. hope this helps.

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