kool kitty89
Senior Master Sergeant
Glider,
On the MK 108's range, HoHun showed in his graph that out to 500m the trajectory is reasonable. (should be somewhat better with the streamlined Minengeschoss Type N -Ausf C L-spur- the tracer element would also improve the ballistic qualities, while the high sectional density will give good speed retention -a property of corse shared with the standard blunt shell)
However the low velocity (granted with relatively good speed retention) will mean a fairly long time in flight, will make it somewhat harder to hit with. (and requiring greater lead in deflection shots as I mentioned previously)
I tend to disagree.
While Tony's approach may seem somewhat arbitrary at first there is a good deal of sense behid it. And conversely, while it may seem a more imperical approach to use the kinetic energy values and add the chemical energy values on top of this for HE/I shells; the latter is IMO somewhat arbitrary as the effect of chemical and kinetic damage is not directly quantifiable in this manner not to mention the difference of HE chemical energy and Incendiary chemical energy. (not to mention different HE/I compositions, and if a pure white phosphorus filler is used there will technically be no chemical energy content at all in less you include atmospheric oxygen)
Firstly, when looking at solid ball/AP/SAP projectiles alone, using Muzzel energy is a rather poor choice as it thend to exaggerate the destructiveness of high velocity rounds compared to lower velocity rounds. Momentum (mass x velocity) tends to give much more realistic figures.
Tony gives a explaination of the choice of his system in the article:
WORLD WAR 2 FIGHTER GUN EFFECTIVENESS
and there's this highlighting the momentum choice:
Using chemical energy would tend to make HE more destructive than incendiary material. (a pyrotechnic mixture, in the case of the the "De Wilde" or Dixon- as well as the derived US incendiaries used a 50/50 mixture of Barium Nitrite and powdered aluminum/magnesium alloy rather like some types of flash powder used in pyrotechics -and these rouds did give quite a flash on impact)
And in particular guns of 13 mm or smaller caliber explosive rounds tended to be rather ineffective (probably not worth adding a delay fuze) despite it being used by both the Germans and Italians (on the .5" Vickers Semi-rimmed export) and thus by the IJA who used the same Italian type ammo. (the 13.2 mm FN Browning -firing the 13.2x99 Hotchkiss round -identical to the BMG save the caliber- offered HE ammunition as well, a did the Russians in the large projectiles of their 12.7x108mm amuntion though I don't know if either of these bothered with Fuzing)
The Japanese also used 7.7mm unfuzed HE rounds.
In any case, incendiary rounds tended to be more effective in such small calibers. (with 15mm/.60 cal weapons in kind of a gray area in terms of HE shell effectiveness, being just large enough to make the addition of a Fuze worthwhile particularly if a thin walled "mine shell" type projectile had been developed)
On the MK 108's range, HoHun showed in his graph that out to 500m the trajectory is reasonable. (should be somewhat better with the streamlined Minengeschoss Type N -Ausf C L-spur- the tracer element would also improve the ballistic qualities, while the high sectional density will give good speed retention -a property of corse shared with the standard blunt shell)
However the low velocity (granted with relatively good speed retention) will mean a fairly long time in flight, will make it somewhat harder to hit with. (and requiring greater lead in deflection shots as I mentioned previously)
Hi Glider,
>Can I ask how you calculate your numbers for effectiveness. Antony Williams site which I am sure you know, gives differing numbers.
I have pointed out my method above, and you'll even find it on Tony's site as well as he added it to his effectiveness page after we discussed the disadvantages of his "rule of thumb" approach on another forum.
>His numbers would give the Ta152 and Tempest very similar stats.
The disadvantage of his rule of thumb approach is that it underestimates low-velocity, high-explosive shells like the MK 108's, so this fits into the picture.
Regards,
Henning (HoHun)
I tend to disagree.
While Tony's approach may seem somewhat arbitrary at first there is a good deal of sense behid it. And conversely, while it may seem a more imperical approach to use the kinetic energy values and add the chemical energy values on top of this for HE/I shells; the latter is IMO somewhat arbitrary as the effect of chemical and kinetic damage is not directly quantifiable in this manner not to mention the difference of HE chemical energy and Incendiary chemical energy. (not to mention different HE/I compositions, and if a pure white phosphorus filler is used there will technically be no chemical energy content at all in less you include atmospheric oxygen)
Firstly, when looking at solid ball/AP/SAP projectiles alone, using Muzzel energy is a rather poor choice as it thend to exaggerate the destructiveness of high velocity rounds compared to lower velocity rounds. Momentum (mass x velocity) tends to give much more realistic figures.
Tony gives a explaination of the choice of his system in the article:
WORLD WAR 2 FIGHTER GUN EFFECTIVENESS
and there's this highlighting the momentum choice:
For all of these reasons muzzle energy (one half of the projectile weight multiplied by the square of the velocity) has not been used to calculate kinetic damage as this would overstate the importance of velocity. Instead, momentum (projectile weight multiplied by muzzle velocity) was used as an estimate of the kinetic damage inflicted by the projectile. It might be argued that even this overstates the importance of velocity in the case of HE shells, as noted above, but the effect of velocity in improving hit probability is one measure of effectiveness which needs acknowledging, so it is given equal weighting with projectile weight.
The relationship between the effectiveness of HE and incendiary material is difficult to assess. Bearing in mind that fire was the big plane-killer, there appears to be no reason to rate HE as more important, so they have been treated as equal.
Using chemical energy would tend to make HE more destructive than incendiary material. (a pyrotechnic mixture, in the case of the the "De Wilde" or Dixon- as well as the derived US incendiaries used a 50/50 mixture of Barium Nitrite and powdered aluminum/magnesium alloy rather like some types of flash powder used in pyrotechics -and these rouds did give quite a flash on impact)
And in particular guns of 13 mm or smaller caliber explosive rounds tended to be rather ineffective (probably not worth adding a delay fuze) despite it being used by both the Germans and Italians (on the .5" Vickers Semi-rimmed export) and thus by the IJA who used the same Italian type ammo. (the 13.2 mm FN Browning -firing the 13.2x99 Hotchkiss round -identical to the BMG save the caliber- offered HE ammunition as well, a did the Russians in the large projectiles of their 12.7x108mm amuntion though I don't know if either of these bothered with Fuzing)
The Japanese also used 7.7mm unfuzed HE rounds.
In any case, incendiary rounds tended to be more effective in such small calibers. (with 15mm/.60 cal weapons in kind of a gray area in terms of HE shell effectiveness, being just large enough to make the addition of a Fuze worthwhile particularly if a thin walled "mine shell" type projectile had been developed)