Rich S. wrote:
wrote in message
oups.com...

In your text you said the gunner fies when the ME 109
is directly behind the B17. For orthogonal ground
tracks, he cannot hit the ME 109 if it is *anywhere* behind
the B17 no matter where he aims because the flight
paths of the ME 109 cannot intersect the path
the bullet takes to the ground.

That's why, in the text, I also added that he "led" the ME-109 exactly
enough. Did you read the entire sentence?

Yes, you added the condition that he leads by exactly the same
amount he would from a fixed condition to the statement that
he fires when the ME-109 is directly behind the B17.
If he waits to fire until after the B17 has crossed the
flight path of the ME 109 he cannot hit no matter how
he aims. It matters not how he leads.


As I said, perhaps I wasn't clear.
He fires directly behind the B-17. The ME-109 is on its way to cross the
flightpath of the B-17.

This you added in a later post. If, while firing straight back
he still leads as if he were firing from a fixed position he
will miss again because the B17 has already crossed the flight
path of the ME-109 by the time he fires.

No matter the direction, if he fires after the B17 has
crossed the flightt path of the ME-109 he misses.



In your illustration, the gunner fires straight back
before the Me-109 is directly behind the B17. He can hit
if he fires at precisely the moment his gun crosses the
flight path of the Me-109.

Not so. The bullet simply falls to Earth and the ME-109 passes safely 50
yards (or so) behind the B-17.

That is true if he leads the ME109 as he would from a fixed
position, or any way other than the *right* way. But there
is a right way. I *changed* the scenario when I said he
fires at precisely the moment his gun crosses the flight
path of the ME-109.

If he fires stright back at that moment,
and the ME 109 is flying at the same airspeed as
the B-17 then the bullet is *also* 50 yards behind the
B17, when the ME-109 crosses. It will be a half inch or
so lower than the altitude at which it exited the muzzle
if it was fired exactly level.

Firing straight back at the moment the B17 crosses the
flight path of the ME-109 essentially drops the bullet
through the flight path of the ME-109. IF the bullet is
still there when the ME-109 arrives, which it will be
for a range of speeds close the speed of the B17,
the gunner hits.

An the gunner can compensate for the ME-109 flying
at a different speed and altitude by firing up or
down a little, again for some range of speeds and
altitudes.

--

FF