Alternate Me 262 armament?

[kool kitty89]

In comparison threads concerning the Me 262 (ie P-80 vs Me 262, best jet etc) the question of armament often comes up.

The 4x MK 108's (100 rpg inner, 80 rpg outer) is a natural choice for bomber killing, with high destructive, capability good rate of fire, and good ammunition capacity. (considering the caliber) the low muzzle velocity being the main disadvantage. (in addition to the MK 108 being fairly cheap to produce)

Some members have proposed 2-3x MK 103's due to their higher velocity. But even with 3x, RoF will be only 1/2 that of the 4x Mk 108's. (and the total gun weight would be ~80% more than with 4x MK 108's in addition to much greater recoil)

Then there's possible mixed armaments. Though these usually have the problem of non matching trajectories. (with the exception of the MG 151/15 and MK 103)



The alternate cannon armaments actually tried on the Me 262 (other than the single ~50 mm guns) would be:
-the /U1 configuration with 2x MG 151/20 (146 rpg) 2x MK 103 (72 rpg) and 2x MK 108 (65 rpg) (total gun weight of ~500 kg)
-and the /U5 with 6x MK 108 with 500 rounds total. (~350 kg total gun weight)

The /U1 configuration would obviously be impractical due to the wildly different trajectories of all 3 weapons. (in addition to weight and reliability problems)

 

[kool kitty89]

There hve also been suggestion that a battery of (say 6) MG 151/15's would be the best from a fighter vs fighter standpoint due to the high RoF and muzzel velosity along with decent hitting power. (though closer to a HMG than a "true" cannon due to the smaller round size and lack of suficient HE capacity) Weight would also be quite comparable to the standard 4x MK 108.


A rather obvious choice is 6x MG 151/20's: offering high rate of fire (slightly higher than the 15 mm) fairly high muzzel velocity, very good HE capacity, and similar weight to 4x MK 108's. The destructive power is not as high as the MK 108's, but still very good. The flatter trajectory and ~2x rate of fire would make hitting targets much easier, particularly at longer ranges and for deflection shots.

With ammunition capacity of ~1050-1100 rounds total (with, say 175 rpg depending on distrigbution) you'd have an average of about 4.5 seconds longer firing time than the standard 4x MK 108 battery.


While this should obviously be better against fighters, I think there are considerable advantages against bombers as well.

And, of course there is no problem with different trajectories as in the mixed armaments.


It seems odd that this arrangement wasn't considered, or it at least wasn't implemented. It would seem to be an obvious choice of armament given that the MK 108 and MG 151/20 were the main LW cannons for the latter part of the war.

-It should be noted that there were problems with reliability of the armament in the /U1 configuration due to the crampped position of the guns. (a generally unsatisfactory arrangement iirc) I believe there were some problems with the /U5 configuration as well, but not as serious. I dout the 6x of the ssmaller MG 151/20's would have posed a problem. (though some of the barrels may project out of the nose due to theit greater length)

 

[Soren]

I say 6x 15mm MG-151's because of they're the best suited for the coming jet age. But 6x 20mm MG-151/20's will also do and will be more effective against bombers.

 

[kool kitty89]

Do you think they could have developed a Minengeschoss type round in the 15 mm version?
It would obviously be less powerful than the 20 mm mine shells, but given that the 20 mm versions held roughly 3x the HE/I of the 20 mm Hispano's shells, a 15 mm mine shell would still likely hold more than a conventional 20 mm shell.

I would use comparisons of the 151/15 and the /20's conventional shells to get a general idea of the comparative capacity, but all I've found is wikipedia's figures which seem rather odd at:

15 mm: 51 g with 2.8 g HE filler

20 mm: 115 g with 3.6 g HE filler (which seems rather low, and would be less HE/weight than the 15 mm shell)

(the mine shell is 92 g with 18 g HE)

 

[KrazyKraut]

2 Mk 108s and 4 MG 151/20 seems the most optimal mix to me. With the 108s only used against bombers it would result in only very little harmonization problems.

 

[HoHun]

Hi Koolkitty,

I'm using this as a point of reference (note: WW2 vintage M2 ... if you have post-war M3 data, please let me know):

6x ,50 Browning M2 - 300 rpg - 372 kg - 100% firepower

The battery actually installed in the Me 262:

4x MK 108 - 90 rpg - 451 kg - 1181% firepower

An obivous alternative for pure fighter-vs.-fighter combat:

4x MG 151/20 (MX) - 200 rpg - 339 kg - 329% firepower

However, while that would give better firepower than the P-80, it's only a fraction of what the Me 262 originally had, so it looks like a bad tradeoff.

Using the 15 mm MG 151 would be even less attractive:

6x MG 151 - 200 rpg - 471 kg - 155% firepower

(Not that any Luftwaffe fighter pilot ever replaced the MG 151/20 against the earlier 15 mm variant anyway - firepower was obiously preferred over muzzle velocity. I list this one only for the sake of completeness.)

Realistically, the Luftwaffe would not sacrifice the anti-bomber capability, and for anti-fighter work just two MG 151/20 using MX ammunition are quite effective (at least equal to the firepower of the 6 x 12.7 mm MG armament of the P-80). Accordingly, a mixed battery might be the best choice, for example:

2x MK 108 - 100 rpg - 237 kg - 591% firepower
2x MG 151/20 (MX) - 200 rpg - 169 kg - 165% firepower
Total 406 kg, 756% firepower.

That would yield a battery of 406 kg with adequate anti-fighter capabilities but a massive short-range punch (which can come in handy against fighters, too). Matching trajectories is not a problem - you wouldn't want to use the MK 108 beyond 500 m anyway, and at shorter ranges the trajectories are in fact well-matched.

It was Luftwaffe doctrine to use only some of the guns or the entire battery depending on the situation, so typically you'd set the MG 151/20 to the A-Knopf and the MK 108 to the B-Knopf on the control stick. For long-range deflection shots, the MG 151/20 would be used by themselves, for everything else, the MK 108 could be added, too.

Regards,

Henning (HoHun)

 

[kool kitty89]

I agree that the 15 mm would be too light an armament (except maybe if Minengeschoss amunition had been designed for it -possibly with ~14 g HE capacity)

I think the 2x MK 108 + 2/4 MG 151/20 could be a good choice too. I still think the all 20 mm armament could be advantageous though, but I'm not sure on a couple things.


You mention the HE(XM) ammunition, or MX-Geschoss. According to Wikipedia, this is similar to the normal mine shell except the HE content is greater due to higher pressures used to pack it. Having a weight of 104 g and containing 25 g HE. (and would thus should have a somewhat lower velocity, arround 750 m/s)

However, on another thread where this came up, Tony Williams mentions this amunition and describes it differently:

The MG 151/20 used the same projectiles as the MG-FFM. Minengeschoss were used from the start (late 1940). There were two standard weights for them; c.92g for the M-Geschoss (fired at around 800 m/s) and c.117g for the HE-T and the later AP rounds (which were usually API or APHE) fired at around 720 m/s.

There were some later more specialised rounds: the Brgr 44 incendiary (essentially a thick-walled M-Geschoss for better penetration into fuel tanks) which weighed 106g and was fired at 745 m/s, and the bigger MX-Geschoss (105g at 640 m/s) which contained more HE: it had a lower velocity because it was so long there was less space for propellant in the case. These were both specifically designed for anti-bomber use.

So it would seem Wikipedia's discription would be incorrect, and I'm not sure of the circumstances of operational use of that amunition either.

 

[kool kitty89]

HoHun, what equation are you using for firepower?

By the conventional: round mass (kg) x 1/2(MV (m/s))^2 x RoF (/s)= power (W) (or devide by 1000 for kW) the figures would be much different. (though of course, this system doesn't take into account the destructiveness of the round used)

 

[Broncazonk]

The Mauser MG 213C 20mm revolver cannon was THE SOLUTION. The Germans had the MG 213 very early on and wasted the entire war screwing around with it.

1400 rpm!!

The muzzle velocity was way over 3200fps and the 20mm shell had the same explosive power as the 30mm mine shell.

Having twin 20mm MG 213C's in every Fw-190 A-D and (3) in the Me-262 would have been devestating to the Allied bomber force.

Not fielding this cannon in 1942 cost the German war effort ENORMOUSLY.

We would have had to nuke German in August, 1945 if this cannon had be fielded.

Bronc

 

[HoHun]

Hi Koolkitty,

>HoHun, what equation are you using for firepower?

Kinetic energy plus chemical energy of the explosive/incendiary content based on the specific energy of TNT.

By the conventional: round mass (kg) x 1/2(MV (m/s))^2 x RoF (/s)= power (W) (or devide by 1000 for kW) the figures would be much different. (though of course, this system doesn't take into account the destructiveness of the round used)[/QUOTE]

Roger, that's kinetic energy only. (You don't actually have to state International System units with the equation by the way, you'd only state units for numeric constants, should there be any. It's not like US units where funny numbers crop up everywhere, forcing you to use pre-determined units.)

As the point of using cannon shell is transporting chemical energy to the target, chemical energy of course cannot be neglected without distorting the comparison.

The chemical energy accounts for 20% of the total energy in a heavy machine gun armour-piercing incendiary shot, 30% to 50% of the total energy in a 20 mm armour-piercing incendiary projectile, and 80% to 90% in a 20 mm or 30 mm mine shell.

Regards,

Henning (HoHun)

 

[kool kitty89]

Do you know anything else about the 20 mm HE XM/MX round?

 

[B-17engineer]

Wasn't there a Me-262 converted to a bomber with a glazed nose toO?

 

[HoHun]

Hi Koolkitty,

>Do you know anything else about the 20 mm HE XM/MX round?

Nothing beyond what's on Tony's site, I'm afraid.

Regards,

Henning (HoHun)

 

[kool kitty89]

Where is it mentioned on Tony's site?

 

[HoHun]

Hi Koolkitty,

>Where is it mentioned on Tony's site?

Hm, I can't find it either. I guess I either misremembered, or the information is from Tony but was posted in some forum thread and not on his site. Do you have his books, by the way?

Regards,

Henning (HoHun)

 

[Soren]

I'd put on the 6x 15mm MG-151's, it's more than enough in terms of punch and the excellent ballistics is large added bonus.

The F-86 Sabre did well with 6x .50cal's which have both poorer punch and ballistics than the 15mm MG-151.

So for fighter vs fighter combat I'd prefer the MG-151, while if the a/c is to be used in mixed roles I'd go for 6x MG-151/20's.

A combination of 4x 15mm MG-151's and 2x 30mm MK103's seems attractable as-well.

 

[drgondog]

I'd put on the 6x 15mm MG-151's, it's more than enough in terms of punch and the excellent ballistics is large added bonus.

The F-86 Sabre did well with 6x .50cal's which have both poorer punch and ballistics than the 15mm MG-151.

So for fighter vs fighter combat I'd prefer the MG-151, while if the a/c is to be used in mixed roles I'd go for 6x MG-151/20's.

A combination of 4x 15mm MG-151's and 2x 30mm MK103's seems attractable as-well.

The USAF came very close to the .60 caliber switch because it did have an effective explosive round capability, the same ballistics as the .5 and easily convertible to the Browning action - basically requiring barrel changes and buffer spring replacement. The decision was pending in the 1952 timeframe and decision was made on $$ as the M2 20mm and the Colt was coming into the inventory and would be was widely available with superior explosive capability... but still not the weapon the MG-151 was.

4 MG 151/20's in the nose seem to be pretty good selection - think I would rather have that with more rpg than the 30mm but confess purely subjective assessment on my part

 

[kool kitty89]

What's the "M2 20mm"?

I didn't know about the proposed .60 cal Browning, there was an earlier US gun, the T17 (derived from the MG 151) but it never entered service. (the only use I know of was the proposed armament of Bell's P-83)

 

[SoD Stitch]

What about the MG 213? It was about to enter service just as the War ended, and would've been an excellent a2a weapon, though the ammunition expenditure would've been about double that of the MG 151.

 

[drgondog]

What's the "M2 20mm"?

The M2 replaced the M1 and was further replaced by the M24 - then the Colt then the M61. The M1/2 and 3 all experienced problems ranging mostly from ammo jams due to headspace and misfires.

I didn't know about the proposed .60 cal Browning, there was an earlier US gun, the T17 (derived from the MG 151) but it never entered service. (the only use I know of was the proposed armament of Bell's P-83)

The proposed .60 caliber was in Test at the Climatic hanger when my father had the Air Proving Ground command at Eglin 1951-1953. I used to have a 250 round box of live ammo that my mother tossed in our move from Virginia to California after my father retired.