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Volker Borchert

wrote:
On Thursday, March 9, 2017 at 9:52:34 PM UTC-5, David R Brooks wrote:

A howitzer fires, with elevation 45 degs. So the shell exits, pointing
upward at 45 degs., spinning. When it hits the target, it is (to 1st
approximation) falling at 45 degs., but the spin should have kept it
pointing upward. This means it would be flying sideways-on.
This sounds wrong to me, but where is the error?\\

The shell flies with its axis in line with the direction that the shell is moving.
So the shell starts out pointed up by 45 degrees , it flight path changes and its orientation also changes. Since the shell is spinning , changing the orientation causes it to precess. And the shell changes from not only the angle up but also changes sideways. So a shell with a clockwise rotation fired due west, will turn so it is going south west.

And it gets worse. A shell fired due North in the Northern hemisphere will go somewhat East because of the Coriolis effect.

Well, it seems the people who designed the Rheinmetall Rh120 knew
what they were doing.

--

"I'm a doctor, not a mechanic." Dr Leonard McCoy
"I'm a mechanic, not a doctor." Volker Borchert