LesB wrote:

On Tue, 15 Jul 2003 10:26:18 +0100, Dave Eadsforth
wrote:

If the optimum range was 300 yards, would this simply be because of guns
being harmonised for about that distance because encounters with enemy
aircraft could not be excluded? Short range was clearly preferable
against manoeuvring targets, but the V1s were not taking evasive action,
and if the Tempests were dedicated to V1s then other harmonisation
patters might have been possible.

Again, relating Bee's tales. The 300 yard range had been found by
trial and error, but the growing success at intercepts was offset by
the fact that too many were still failing to destroy their targets.
The fighters (Mossies, Tempests, Spits, et all) were firing off all
their ammo without causing lethal damage. Seems there was a clear
reason for this.

Throughout the war the guns of fighters had been harmonized not on a
point for optimum concentration at a given range, but on a basis of
calculations by gunnery experts in the Air Ministry Armaments Branch,
this harmonization was called "Fighter Command Standard Spread
Harmonization".

When the guns and sight were harmonized to this standard against the
"pattern" boards it looked as if all the guns were aimed in slightly
different directions. The reasoned explanation for this method was
that the calculated "dispersion" pattern would ensure the maximum
number of rounds would hit the target from any one burst of fire. With
experience, says Bee, many pilots doubted this and so, at Newchurch,
they took matters into their own hands. They knew the Tempest was
extremely stable and the four 20mm cannon had a fairly high accuracy
over a range of 1000 yards. The V1 however was a difficult target with
its 3 foot dia fuselage making it difficult to see at long range.

snip

I think this last point is what would make trying to fire at longer range
difficult/impossible. If you can't see the target to aim, everything else is
irrelevant.

Guy