NigG,
You've given me so much material here (and all "up my street") that I hardly know where to start !
...The ground was often too featureless for Wingate's suggestion that troops would identify targets by sending a map reference...
It was (nearly always) too featureless ! Only in cases like the Akyab Jail strike ("Pilot's Brevet" p.133 #2658) was the target so big that you couldn't fail to find it or miss it when you did. A grid reference in a thousand square miles of jungle means very little to a poor pilot or nav in an aircraft, I'm afraid.
...one at each end of the target at the appointed Time Over Target (TOT)...
No, you can't rely on the timekeeping being as accurate as that. Best idea is for the Army chaps to "gather round" as close as they dare, wait till they can hear and then see us coming, pause till we are about 45 degrees elevation from them and whack down the smoke.
...I recall my father explaining that there was an added complication when they were using their low level dive technique, during the monsoon, when cloud was too low to permit a vertical dive. There was a risk of bombs missing the target, usually over-shooting it...
Even in vertical bombing, there was less "line error" (left-right) than over/undershooting (forward-back). As the dive angle decreases, the line error, if anything, should decrease, but the over/undershoot will increase, as the nose has to be pulled up more (a lot more in a VV, with its long nose and no AoI), and the release point becomes more of a guess. As you say:
...This was potentially hazardous for nearby friendly troops. So it was important for the pattern of mortar smoke bombs to define where the troops were. That way, the dive was made across the front of the troops, so that any over-shooting bombs or bombs falling short wouldn't imperil them...
Good idea (never did it myself, or heard of it being done). Can see the sense of it in a shallow dive, where you can choose your heading in the dive. But vertical, your aircraft chooses your heading for you, as you are "weathercocking" (twisting) all the time down to keep the yellow line on target, so it is pot-luck whichever heading you bomb and pull-out on.
(Still small voice: why not use the Hurricane and Beaufighter for LL bombing, as they can see so much better, and do it all the time [in all weathers], and so are much better at it ?)
...The sixth and twelfth aircraft carried cameras, which the pilot would switch on before he peeled-off into the attacking dive. In an attack by 6 aircraft, they would then record the accuracy of bomb-strikes of the first 4 aircraft. Film would be assessed by 221 Group Ops Room, who would decide if a second attack was necessary, depending on the type of target...
And there was me, with my ("Pilot's Brevet", p.135, #2684):
...An air staff officer back at Group had a bright idea (make for the hills, chaps!) Why not kill two birds with one stone? Fit a camera in the bomb bay of the last Vengeance to go down, and let him take the photographs himself after he's bombed. They checked for free space in the bay: it could be done..
Had to think hard about this. I assume the camera was fitted facing forward (not in the bomb-bay, as in my case). 6 (?) might see the leader's bomb flash and smoke. Ye..ss, but my guess would be that 4 or 5 would be better, 6 might see only the dust and smoke cloud kicked up by 2 and 3. But they were the ones who were doing it, they should know.
(You'll have seen "
Vengeance" pp 150-151 - wonderful series of shots, but must have been taken from some other aircraft.
...Sometimes the 12 would separate, 6 attacking one target, while the other 6 went for another one...
That's more like it !
..3 were enough to destroy a bridge...
True - but only provided you hit it ! A bridge is notoriously difficult to hit, you have to destroy a span or an abutment (the Narigan bridge in Akyab survived many attempts to hit it, before it was brought down, I believe).
... It also gave optimal protection against attack by fighters, the rearward guns, combining their fire power...
Well, I don't know what air gunnery refresher training 84 Squadron had (and the IAF, possibly at OTU). The rest had none. In your back seat might be a Navigator who had never touched a Browning in his life, still less fired one, or an old Blenheim Wop/AG or AG who was last in its two-gun turret in early '42.
The Vengeance had a Heath Robinson affair in the back. Basically, it was a pillar on a joint on the cockpit floor. This could wobble about all over the place, but was restrained by a couple of links. On top was the twin-gun assembly which had limited free movement. It was all handwork, there was no power assistance.
And even 12 of these are going to fight off a determined attack by a couple of pairs of well-handled "Oscars" ? (100 mph faster than the formation, much more agile than even a single VV, and more heavily armed ?)
Forget it ! It would be the Fairey "Battle" v. Me109 story ('39-'40) in France all over again. Our back-seat men would blaze away valiantly, but would be unlikely to hit anything other than their own tails (or somebody else's), what with their pilots screwing the things round desperately to turn into the next attacker.
Good thing it never happened !
Much too much, I'm afraid.
Danny.