Best armed fighter

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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:

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.
Click to expand...

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)
 
The problem I have with William's approach is this:
For projectiles with a chemical content, we increase this by the weight fraction of explosive or incendiary material, times ten. This chosen ratio is based on a study of many practical examples of gun and ammunition testing,
Click to expand...
I would really like to know the study he mentions, but there is no link or source what-so-ever. What guns were studied, what calibre, what period etc... For example an educated guess tells me a study on modern guns will give a much more pronounced energy advantage for "chemical guns", as modern chemical agents tend to be more effective. As it stands his study is nicely written and probably gives acceptable relative outcomes, but the formula above looks largely arbitrary to me.
koolkitty said:
And in particular guns of 13 mm or smaller caliber explosive rounds tended to be rather ineffective.

In any case, incendiary rounds tended to be more effective in such small calibers.
Click to expand...
What do you base this on?
 
I also would be interested to see what tests that ratio is based on. However it does corespond fairly well to the USN comparison of the Hispano to the .50 M2. (3x as effective at close-medium range, in fact Tony's figures are even more in favor of the cannon, the all-energy figures are significantly higher still)

On the HE machine gun rounds, there are a few reasons behind that statement (besides the "20 mm was determined to be the smallest caliber for a shell with worthwhile explosive capacity" statment -which is obviously debatable), The MG 131 HE round carried only 3.5% filler (1.2g) and the Italian-Vickers 12.7 mm even less at 2.2% (.73g) while the .50 BMG and .50 Vickers carry ~5% as pure incendiary rounds. ("de wild" derived)

Things may be different for the somewhat larger projectiles of the 13.2x99 Hotchkiss and 12.7x108 Soviet amunition, but I'm not sure. (both offered HE ammo and the 12.7x108's API round carried 4.2% incendiary compared to only 2% for the .50 BMG's API)

And if it was possible to make an effective "mine shell" in such calibers it may have been worthwhile as well. (though pure incendiary may have still been more effective here)
 
Hi Koolkitty,

>Which clearly shows that the G.55 had a higher total ammo power, granted at a lower fire power.

That was a comparson G.55 vs. Ta 152H, the other was a comparison G.55 vs. Fw 190A-8 (which have, as I pointed out, the exact same number of 20 mm rounds).

>And according to wikipedia's figures, the G.55 had 300 rph 12.7mm, 200 rpg for the wing 20mm's, and 250 rpg for the nose cannon.

Oh, Wikipedia ...

>I also beleive the Ta 152H was intended (high altitude optimized) for fighter vs fighter combat, not specifically for bomber interception. If the latter had meen the case, a heavier armament would be likely be fitted.

Quite right. The Ta 152C would have two additional MG 151/20 cowl guns, and two outer wing MK 108 were possible too. It was even planned to use an engine MK 103 and to allow mounting of MK 103 gondola (instead of the outer wing MK 108). I don't think there was ever an aircraft such equipped, though.

Regards,

Henning (HoHun)
 
Hi Glider,

>If you allow for the ballistic drop of the Mk108, then the 20mm are going to miss.

Oh well, you talked about the 30 mm being unsuitable for long range fire, which is not true.

>RAF aircraft also had sophisticated sights and they would be hitting with all their 20mm.

Yes, and in the case of the Meteor, with 4.2 MW combined firepower. Now the Ta 152H's single 30 mm offers 5 MW firepower, so when you simply cut out the 20 mm, the Ta 152H is still superior.

(And even more than these muzzle power figures indicate - at long range, the kinetic energy has been considerably reduced by drag, while the chemical content is just as powerful as it was at the muzzle.)

>Again true but to a degree, the fixed gun is more accurate than the turret and the HMG loses more of its effectiveness at longer ranges. So by getting close you lose a lot of the advantages of the fixed wing fighter.

The determining factor is the required mission effectiveness ratio for the fighter - even assuming the exchange ratio were more favourable at extreme ranges, the total number of downed aircraft would be down. In the Luftwaffe experience, effectiveness dropped with 1/r^2, so if you're out at three times the range, you get only 1/9 of the kills.

>As mentioned a number of times I believe this is a more flexible arrangement.

Now there is an adjective that means everything and nothing.

>>Its armament was not changed after Korea though - just as I said, the Soviets continued to use the MiG-15's battery in the MiG-17.

>Neither were the weapons carried in the USAF F86.

Whom are you trying to fool? The weapons carried in the USAF F-86 were changed in Korea already because of their inadequacy, and there were quite a number of 20-mm-armed F-86 variants produced afterwards.

That the USAF considered the 12.7 mm guns woefully lacking in the light of their Korean experience is beyond doubt, and to me it looks as if you're trying to throw up a smokescreen here.

>Again true but the point was that the first Soviet fighter produced after Korea went to a single weapon, away from a split 37mm/23mm payload. They had learnt the lesson.

The MiG-17 was the first Soviet fighter produced after Korea, and it had the combined armament for its entire service life, with the exception of radar-equipped aircraft which had the 37 mm cannon replaced by another 23 mm cannon to compensate for the additional weight of the radar and associated equipement.

If the mixed armament would have been considered a mistake, the 37 mm cannon would have been replaced by a 23 mm cannon on all aircraft in just the same manner, which didn't happen, so you have no point.

And to equate the mounting of a much more powerful battery in the MiG-15's successor's successor aircraft to the ripping out and replacing of the F-86's recognizedly inadequate armament in the framework of a purposeful project while the war was still going on takes you half the way to my ignore list already.

I see a pattern there, Glider - play fair, or don't play at all.

Regards,

Henning (HoHun)
 
Hi Kitty,

>While Tony's approach may seem somewhat arbitrary at first there is a good deal of sense behid it.

It doesn't appear "somewhat arbitrary", it appears completely wrong. There is no reason for linking chemical content and muzzle velocity I could see, and I note you didn't provide any either.

>Tony gives a explaination of the choice of his system in the article:
WORLD WAR 2 FIGHTER GUN EFFECTIVENESS

You can assume I'm familiar with that as I criticized it when it came out, leading to Tony's addition. If there is anything you consider important, it would help if you'd explain it here because I still don't follow Tony's original explanation.

>and there's this highlighting the momentum choice:

Which makes claims, but gives no physical reason.

>fire was the big plane-killer

Unproven, probably resulting from a misunderstanding of the findings of a single report. (If fire was witnessed during the destruction of an aircraft. that doesn't mean that fire was the cause of the destruction - it could just as easily have been the result.)

>And in particular guns of 13 mm or smaller caliber explosive rounds tended to be rather ineffective [etc.]

Right - and that ineffectiveness is clearly evident in the energy figures, too.

Regards,

Henning (HoHun)
 
Hi Koolkitty,

>I also would be interested to see what tests that ratio is based on. However it does corespond fairly well to the USN comparison of the Hispano to the .50 M2. (3x as effective at close-medium range, in fact Tony's figures are even more in favor of the cannon, the all-energy figures are significantly higher still)

Well, I guess the question on what the US Navy based that conclusion on is just as interesting.

The Luftwaffe compared the MG 151 in the 15 mm variant (which is pretty exactly twice as powerful as the 12.7 mm Browning) to the MG 151/20 cannon, and found the 20 mm cannon to be 3.25 times as effective. (This agrees well the energy-based analysis.)

Regards,

Henning (HoHun)
 
lesofprimus said:
Real interesting stuff here fellas.... Surprised Drgondog aint in this...

If we can guys, lets keep this in the boundry of single engined fighters, and those utilized for air to air combat...
Click to expand...

Dan - it just seems pretty straightforward that the 262, Fw 190A8, He 219, P-61 and F7F were the heaviest armed figters - and only one was a single engine fighter. Only the A8 had to depend on synchronization of any kind - all the rest push one 'solid tube' of very heavy firepower out of the nose.

And to think that one A-10 exceeds them all.
 
I admit to having been doing some thinking and have some doubts about the statements being made.

For Example
The 30mm Mk108 I do not see as being acurate up to 500m and then suddenly dropping off. Its a heavy shell with a low MV. Gravity will take over and the shell drop. The statement earlier in the thread that you can keep the pipper on the target up to 500m I frankly disbelieve.

There are two factors in external ballistics, Muzzle Velocity and Ballistic Co efficient, with the MK108 is well below average on MV.
The Ballistic Coefficient of the 30mm will tend to be slightly better than a 20mm but nothing like the difference between the different MV.
 
HoHun said:
Hi Glider,

>If you allow for the ballistic drop of the Mk108, then the 20mm are going to miss.

Oh well, you talked about the 30 mm being unsuitable for long range fire, which is not true.
Click to expand...
I believe that it is unsuitable.

Can I ask how you calculate the 4.2 MW. I mention this as you give the Tempest a higher power when they are the same guns.
(And even more than these muzzle power figures indicate - at long range, the kinetic energy has been considerably reduced by drag, while the chemical content is just as powerful as it was at the muzzle.)
Click to expand...
You are of course correct but Kinetic Energy is less important in a cannon shell as they can penetrate almost any armour carried on an aircraft. The 20mm Hispano could penetrate 20mm at 400m, the punch is in the explosive content so any drop in Kinetic energy is of little consequence. Using low MV weapons that is probably true but to apply it to longer ranged weapons is an unproven fact

The Mig 17 was not the first soviet fighter produced after Korea, the Mig 19 was and that switched to a common weapons system.

True the Mig 17 kept its weapons for its life but its my believe that that was also the case in the USAF.

I believe the following to be true. The USAF had the A and E which kept the 0.5 HMG, The F86D had rockets, The F86K had cannons but it was my understanding that this was for export only and not used in the USAF.
I certainly could be wrong and am happy to be corrected.

The USN had always been keen on the 4 x 20 and their aircraft were so armed but not the USAF.

Re Playing fair I have. Where I have made mistakes I have admited them and supported my statements. If that gets me half way to an ignore list, then I leave it to the people who are looking at this debate to make their own assumptions.
 

You mistake accuracy for ballistic performance - they are not the same. The MK 108 was indeed very accurate with its short, stubby barrel and low muzzle velocity - accurate means the gun had very little dispersion. High muzzle velocity, long barelled automatic guns, quite contrary to what instincts would tell you, are less accurate.

I have seen a LW accuracy table, and the ranking (from the most to the least accurate) was the follows:

MG FF
MK 108
MG 151
MK 103

The dispersion of the MK 103 was twice that of the MG FF - the reason is barell flexing. Longer barrel, more powerful (ie. higher Mv) round - more flexing.
 
Careful, Glider, or you will be relegated to the ignore list. As regards the ballistic coefficient of a projectile the relationship of length to diameter is important but also the form or the shape of the missile plays a big role. Of course gravity begins to act as soon as the missile leaves the muzzle but so does friction. The question I have had from the beginning is, based on illustrations I have seen, some of the cannon rounds appear to have a not very efficient shape or form as far as BC is concerned.
 

You are of course correct when you say that accuracy isn't the same as ballistic performance. However, although a longer barrel can mean more flexing that depends on the design of the gun. For instance the French 20mm was very accurate but also one of the longest cannon carried by any aircraft.
Also a short barrel with a powerfull cartridge can have an equally detremental effect on accuracy. It depends on how well matched the cartridge is matched to the gun.
Note - I am not saying this applies to the mk108 just making an observation about flexing
 

Rennich
The Basllistic Coefficient is made up of two factors the Sectional Density and the Form Factor.
The Sectional Density will favour the 30mm, its basically a calculation concerning the density of the shell and the frontal area of the projectile.

The Form Factor is basically the aerodynamics of the shell and is measured. I don't have the numbers but like you would be suprised if there is any significant difference between most shells of ww2.
 
I have a source which has an actual sized illustration of four of the German 30 mm shells and three of the four appear to have a shape which would not lead to a high BC.
 
Hi Glider,

>Re Playing fair I have.

If that was the best you could do, you're on ignore now.

Kind Regards,

Henning (HoHun)
 
renrich said:
I have a source which has an actual sized illustration of four of the German 30 mm shells and three of the four appear to have a shape which would not lead to a high BC.
Click to expand...

http://www.ww2aircraft.net/forum/weapons-systems-tech/30mm-mine-shell-12821.html

Komet weapons: MK 108 cannon

The standard Minengeschoss shells were bunt nosed like their 20 mm counterparts (and fairly similar to their "normal" low capacity cousins -blunt from nose fuze)

The streamlined "Type N" shell (fitted with tracer) was much more streamlined, in fact it was probably the most streamlined cannon shell of the war. (in fact it apears to be better than the modern 20 mm HE shells used by the US millitary) The Shells of the British ADEN (and I assume the similar French DEFA) had rounds very much like the "Type N."

Even with the blunt shells the sectional density was quite high. (~40% higher that of the .50 Browning's round)



HoHun, I agree that the chemical and kinetic damage should be ranked seperately. (and HE vs Incendiary should probably be ranked seperately, and the varying characteristics of the HE or I compositions be taken into account as well, with incendiaries being particularly diverse: from phosphorus, to "flash powder" like pyrotechnic mixes, to thermite)

However I dostill think Momentum is a better measure of destructiveness than kinetic energy when looking at that alone. Of course that makes adding a cemical score trickier (though using the chemical energy is oversimpified in any case IMO) and still leaves the question on how to compare th two.

Ideally, you'd use a statistical analysis comparing the average number of hits from solid shot, and varying degrees of HE content (say ranging from 6 to 25% by mass) as well as incendiary mixtures in a similar manner. (possibly HE/I maxes as well)
Then compare such results through a variety of different caliber bullets/shells.

Perhaps we should start a seperate thread on this.


I wonder if Soren has any thoughts on this, I seem to rember that he's pretty knoledgeable on this area. (particularly ballistics -which has admittedly spurred a few arguments when making comparisons of ballistics with aeordynamics of aircraft )
 
Henning

Its a shame that you react this way when someone has a differing opinion and explains their case. I admitted when I made mistakes and its a shame that you don't feel able to do the same.

Nearly all my comments have been factual that you can check and I am open to correction. However you prefer to put me on an ignore list, that is your choice.

Until the next time
 


The blunt shell would actually have basically little if anything, to do with the sectional density but it would have an impact on the Free Form which is about aerodynamics.
Interestingly its the Tracer that has a large impact on the aerodynamics, as it causes an increase in pressure at the rear of the shell where there is an area of low pressure. As the shell passes through the air it creates a vacuum effect behind the shell, which in turn sucks in the air that the shell is passing through. This causes turbulence (drag) and the drag reduces efficiency. By increasing the pressure the tracer reduces the amount of turbulence and reduces the drag. As you would expect streamlining has a similar effect.
 
Hi Koolkitty,

>HoHun, I agree that the chemical and kinetic damage should be ranked seperately. (and HE vs Incendiary should probably be ranked seperately, and the varying characteristics of the HE or I compositions be taken into account as well, with incendiaries being particularly diverse: from phosphorus, to "flash powder" like pyrotechnic mixes, to thermite)

Well, if you come up with a method, and with the data required to feed it, I'll definitely have a thorough look at it However, you're going to need a certain level of abstraction in order not to get swamped with detail, and that's what the energy-based method provides.

>However I dostill think Momentum is a better measure of destructiveness than kinetic energy when looking at that alone.

Hm, why? The damage potential is limited by the kinetic energy, and as soon as you deviate from that, you already make an assumption regarding the damage mechanism, which depending on what the projectile will actually hit can be wrong as easily as right.

(The same problem applies to your suggestion of analysing the number of hits - unless you're talking about hits on actual aircraft, but we'd have to find something very specific there.)

Regards,

Henning (HoHun)
 
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