Range Report Drag coefficient changing with velocity

[flyfisherman246]

I have searched high and low and can't find a good explanation on why the drag coefficient of a bullet gets higher as velocity slows before it hits transonic. What is causing the bullet to have less drag at higher velocities?

 

[CoryT]

It relates to the position of the shock wave and the change in flow at the base. Base drag is quite significant, which is why we have boat tails. If you look at spark photographs that show the air flow around the bullet, you can see the change in position of the bow wave, the changes in the boundary layer flow and the increase in base drag as the projectile slows down.

Bullet Shockwaves in SloMo

 

[flyfisherman246]

It relates to the position of the shock wave and the change in flow at the base. Base drag is quite significant, which is why we have boat tails. If you look at spark photographs that show the air flow around the bullet, you can see the change in position of the bow wave, the changes in the boundary layer flow and the increase in base drag as the projectile slows down.

Bullet Shockwaves in SloMo

Dude!!! That is so awesome and makes so much sense. Thank you so much for posting that.

 

[Long Range 338]

Probably the coolest slo mo video ever, thanks for posting that up

 

[Steel head]

That channel is gold

So much cool stuff

 

[flyfisherman246]

It relates to the position of the shock wave and the change in flow at the base. Base drag is quite significant, which is why we have boat tails. If you look at spark photographs that show the air flow around the bullet, you can see the change in position of the bow wave, the changes in the boundary layer flow and the increase in base drag as the projectile slows down.

Bullet Shockwaves in SloMo

So I see what you are saying here, and this makes sense. What about the added drag of the increasing yaw angles at longer ranges. I'm guessing this has something to do with it as well?