rotation of the earth

[The Reaper]

I saw a great article about ballistics in Very High Power magazine.

They went to Yuma and got the YPG instrumentation to help them track .50 bullets in flight.

One of the things they looked at was the attitude of the bullet at impact. Turns out that as you state, the bullets fly nose high from max ordinate on (or just never turn nose down from their initial launch attitude).

Very weird.

TR

[HOLLiS]

Originally Posted by longrange1947

That is why alot of the ballistic "predictor" programs fail as they do not take into account that the BC changes with velocity. Sierra, atleast, shows three to four BCs with speed envelopes to get a basic prediciton. Presicion Workbench uses a modeled curve based on actual performance of your bullet/weapon combination at specific ranges.

As the velocity approaches trans sonic it falls off rapidly and then during subsonic shift it jumps back up. It flies really well but is very suseptable to any changes in air resistance as from wind shift to thermals. The round is spinning at a higher ratio to forward velocity so the round is now nose high and overstablized (gyroscopic) making it even more suseptable to violent tilts in axis, just as a gyroscope tilts once upset.

Predicitng bullet flight at those speeds is right next to impossible as so many things come into play.

Thank you, that is what I thought/leanred. I met some Greenill formula fanatics that told me I was FOS.

Thanks for the excellent read. My biggest mistake was sleeping too much in calculus class.

[kgoerz]

Originally Posted by longrange1947

That is why alot of the ballistic "predictor" programs fail as they do not take into account that the BC changes with velocity. Sierra, atleast, shows three to four BCs with speed envelopes to get a basic prediciton. Presicion Workbench uses a modeled curve based on actual performance of your bullet/weapon combination at specific ranges.

As the velocity approaches trans sonic it falls off rapidly and then during subsonic shift it jumps back up. It flies really well but is very suseptable to any changes in air resistance as from wind shift to thermals. The round is spinning at a higher ratio to forward velocity so the round is now nose high and overstablized (gyroscopic) making it even more suseptable to violent tilts in axis, just as a gyroscope tilts once upset.

Predicitng bullet flight at those speeds is right next to impossible as so many things come into play.

I'm stealing this one also....Is Ed still out there or are you the only civilian working there? I heard he retired, or was sick. Ill be back late June. Might just work locally after this. I never thought I would say I'm getting tired of Bogotá. Let me know if you need anything. I'm getting some gear made here. Just for personal use or a gifts, not selling it. Me and Doc have something for ya.
It's still cheaper to have stuff made here but not as cheap as it use to be. We don't use Commando DE Selva as much, couple of other Gear makers have sprung up.

[Team Sergeant]

Originally Posted by The Reaper

One of the things they looked at was the attitude of the bullet at impact. Turns out that as you state, the bullets fly nose high from max ordinate on (or just never turn nose down from their initial launch attitude).

Very weird.

TR

My guess would be that as the bullet slows gravity starts to take affect and changes the angle of the pressure wave moving in front of the bullet.

This pressure wave might keep the nose up at slower velocities where at the higher velocities the pressure wave would be equally distributed.

Just a guess.

TS

[longrange1947]

KG - Ed retired last year. He is shooting for the Sierra Rifle Team and is on the Palma team so training for his matches. I have no idea how many bullets he sends down range but he fires about 100 rds a day just in .22 to stay up on the basics.

Give me a buzz when you get back in the area and I'll buy you a beer.

Not too sure I am ready for whatever you and NDD have dreamed up.