"Volker Borchert" wrote in message
news
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.

Joseph Whitworth knew what he was doing in 1860.
http://civilwarwiki.net/wiki/12_pdr....hloading_Rifle
"At 1600 yards the Whitworth gun fired 10 shots with a lateral
deviation of only 5 inches."

But the Confederacy had only a few pieces of superior British
artillery, and Lee's Chief of Artillery was incompetent.
https://en.wikipedia.org/wiki/William_N._Pendleton
At Gettysburg Lee chose a talented but inexperienced junior officer to
command the artillery and Pendleton mainly interfered with him. The
Union artillery commander tricked him by pulling guns out of action
randomly as though they had been destroyed. Gunpowder smoke obscured
what was really happening. Expecting a disaster he'd been unable to
prevent, General Longstreet delegated the decision on when the
infantry should charge to the junior artillery officer who didn't
realize he hadn't really crushed the opposition that then massacred
Picket's Charge.

-jsw