Hi Juha,
>More or less I agree but I'd put it a bit more mildly, the harmonization distances were usually reasonable and effective range.
Not a bad way to put it
Neil Stirling once posted excerpts from a RAF gun camera analysis report showing that 52% of the kills were achieved at less than 200 yards range, 34% from 200 to 400 yards, and only 14% at more than 400 yards. (And slightly more than 50% of all these kills were achieved with gyro gunsights ...)
It's not like the guns just stopped to function at long range, effectiveness just kept decreasing smoothly with increasing range.
>FC test early in the war showed that when pilots were ordered to fire at target at300y actual distances were 800-1200y, so pilots were advised to halve their range estimates and double their estimate of the lead and also advised to open fire as close as possible.
Hm, Fighter Command training doctrine seems to have been rather "rational", including setting the sight to the target wingspan, estimating the angle-off and the target speed, and calculating the required lead. The problem with this method is that it is slow, while air-combat is fast paced. I'm convinced a "flash card" approach (as developed during WW2 for aircraft recognition training) would have been more useful. Unfortunately, I don't know what doctrine the Luftwaffe used, but I noticed Reschke made mention of a card game (for solitary play) distributed by the Luftwaffe that was supposed to train the pilots in deflection shooting. It would be interesting to know if this worked on the "flash card" principle.
(Luftwaffe aircraft recognition seems to have relied on learning characteristic features for every plane, and I don't think they ever adopted the flash card method there. On the other hand, I've read that Luftwaffe "Morse" key operators were trained with a "high speed" approach that could be considered the acoustic equivalent of the flash card approach
To this day, "to morse" is a verb in German, by the way.)
>Absolutely true but I was thinking easing the sighting problems not increasing firing range.
Agreed, I just mean to highlight that as always in aviation, there is a trade-off involved. In the case of the MK 108, the higher firepower at short range out-performs the accuracy gain one might have from a higher muzzle velocity.
>IMHO maybe the best fighter gun was Hispano Mk V, clearly higher mv and higher rof than MK 108 but clearly less effective ammo with 2/3 weight. But it's matter of opinion. A bit large dispersion possible with tvo Mk Vs vs one MK 108 (weapon weight 84kg vs 60kg) would probably be preferable for average pilot, crack shots being rare.
The Hispano V certainly is a good all-around cannon, and I agree that it is to preferred over the Hispano II because it gained some firepower over the older gun at the expense of a bit of muzzle velocity.
However, when comparing fighter gun installations, the ammunition supply should not be neglected. Here are some batteries with equal ammunition and roughly comparable firepower (based on total muzzle energy):
1x MK 108 - 87 rpg - 111 kg - 221% firepower
2x Hispano V - 212 rpg - 188 kg - 109% firepower
8x ,50 Browning M2 - 250 rpg - 452 kg - 100% firepower
25x Browning ,303 - 399 rpg - 549 kg - 96% firepower
Starting with the smallest calibre, the 25-barrel rifle-calibre machine gun battery obviously will be very hard to install in a single-seat fighter for lack of space
The eight heavy machine guns are realistically possible, but comparing the complete installation to the twin Hispano battery, it's obvious that heavy machine guns come with a hefty weight penalty for the limited firepower they offer. The MK 108 not only is lighter yet than the Hispano cannon, but it additionally doubles the firepower. It can also be installed in the nose of a conventional single-engine fighter (if the engine is designed for it), while the Hispano V is unfit for synchronization so that you either have to restrict yourself to one engine cannon, reducing firepower, or mount the pair of them outside the propeller disk, with the ill effects we already discussed.
So let's change the battery to 3 Hispano (one engine cannon, two wing cannon - the Merlin didn't allow this, but the Hispano-Suiza did), comparing it to the MK 108/MG 151/20 combined battery I mentioned:
3x Hispano V - 141 rpg - 230 kg - 163% firepower
1x MK 108 - 43 rpg - 85 kg - 221% firepower
2x MG 151/20 - 105 rpg - 128 kg - 112% firepower
Total: 213 kg - 333% firepower
So I get about twice the firepower for the Ta 152 cannon setup compared to the triple Hispano V setup, at roughly equal weight if I use comparable ammunition loads. The Ta 152 setup would lose some firepower at longer ranges, but as the RAF report quoted above shows, long range fire was the excepton rather than the norm. Additionally, the MG 151/20 can be synchronized, and the wing-root position of the Ta 152's cannon has the well-known ballistic advantages over the wing-gun position necessary for two of the three Hispanos we're considering.
(Grr, now I notice that I probably should have used the data for the somewhat more powerful MX ammunition introduced late in the war for comparison to the late-war Hispano V. Well, I'm not going to re-do the calculations ... the picture is clear enough after all
>True but 2-3 20mm hits probably at least remove enemy fighter from that fight
Sometimes maybe, but taking into account that the Luftwaffe considered an average of 6 x 20 mm required to destroy a fighter aircraft, I don't think it's realistic to expect that as the normal result.
>>"In my opinion, sacrificing muzzle velocity makes sense because the resulting firepower makes it possible to score decisively even in snapshots, which can be achieved by criss-crossing the enemy's path instead of tracking him."
>But it makes hitting with those snap shots harder.
The lower muzzle velocity makes it harder to achieve nominal hits, but at the same time the massive firepower of the MK 108 makes it much easier to achieve decisive hits. It is a trade-off ... you sacrifice hit probability to increase the probability of a kill.
It also means that snap shots are a worthwhile tactic at all, as with a lower-firepower weapon, you might be forced to go for a tracking shot, which means that have to commit yourself to trade energy for angles - which can be a rather dangerous course, especially if you're up against multiple bandits.
Regards,
Henning (HoHun)
