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ww2 fighter armaments effectiveness..

Discussion in 'Aircraft' started by sniper1946, Nov 13, 2009.

  1. sniper1946

    sniper1946 Expert

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  2. T. A. Gardner

    T. A. Gardner Genuine Chief

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    I had a discussion on this paper with Tony on another board when he first put it up. While he does a decent job of measuring the weapons he left out a useful discussion of how these weapons interact at the receiving end and also how effective they are within the aircraft system itself.

    The second issue first: Muzzle velocity matters in aerial combat...ALOT. Low velocity, low rate of fire weapons, regardless of their effectiveness, are limited in usefulness compared to ones that at fire high velocity and rates of fire.
    What this boils down to is that in aerial combat closing rates are high and firing times are short. By having a higher velocity higher rate of fire weapon the firing aircraft has a greater firing time (that is it can open effective fire at longer range) and puts more rounds down range than its low velocity low rate of fire counterpart.
    As I recall I compared an Me 262, Fw 190A8 and a P-51 in this respect usiing the half second flight time of their rounds (this gives a gravitational drop that is not significant enough to heavily disperse or cause arcing flight of the rounds) against a target at several closing rates like 100 mph, 200 mph etc.
    I then used Tony's destructiveness data as given with this and assumed a constant rate of hits like 5% or so of the rounds fired.
    The result was that the Fw 190 and P-51 did better than the Me 262 for destructive firepower. The Fw 190 with its cannon was much better while the P-51 made up for its lack of striking power through rate of fire and velocity. The Me 262 was hit on two accounts: First it had the highest closing speeds so its firing envelope shrank and, two it also had the lowest velocity, slowest firing weapons. Yes, one or two hits were devastating but you had to get one or two hits.

    The second problem was how the weapons were mounted, how they were aimed and, how their hits interacted with the target. For example, Tony gives alot of destructiveness to HE filled rounds. This is probably overrated. There are essentially three ways to effect a kill on an enemy aircraft:

    Structural damage: That is the airframe itself comes apart and the plane no longer flies.
    Damage to systems: Shooting out the engine, controls, fuel, etc., causing the aircraft to no longer be capable of controlled or powered flight.
    Crew kill: That is killing or incapacitating the crew.

    HE rounds that do not cause much fragmentation have limited effect on an aircraft. They can blow fairly large holes in the skin and can cause spectacular damage to things like fuel tanks but, rarely result in the kind of damage that takes the plane down on their own. Instead, they rely heavily on secondary damage such as fragments generated from the target, fires starting in a fuel tank where the tank doesn't empty quickly, that sort of thing. Blast alone is not very effective at taking the plane down.
    A fragmentating HE round on the other hand is more dangerous. It generates fragments that can cut through heavier structurial members, cut control lines, hydraulic lines, or tear electrical system wiring to pieces. They are more likely to score system and crew kills than a blast HE round is.
    The number of hits can also be important here. Lots of penertating effective hits mean more chances something vital is going to get damaged. A few heavy hits are often less likely to score such damage than a somewhat less effective round (even a solid bullet) that is sprayed in large number over the target.
    Now, in this respect there is a bottom end to this effect. Small caliber rounds lack the penetrating power necessary to do substancial damage. Hence the move away from .30 caliber guns in WW II.

    Anyway, what it boils down to is that the most effective aerial guns combine high velocity with a high rate of fire and, a round that can cause sufficent damage to an enemy airplane on striking it as to have the potential to score a kill on a vital system.
    This is why you see even today that aircraft have not moved much beyond the 20mm - 30mm range in gun size for air-to-air combat and why those same guns have had their rate of fire greatly increased.
     
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  3. sniper1946

    sniper1946 Expert

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    thanks for that heads up t.a.,ray..
     
  4. marc780

    marc780 Member

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    I wont attempt to quote your whole reply even though it is a good one. You make make valid points that are no doubt accurate.
    The Germans decide at some pointmid-war , using most of the factors you mention, that something called "weight of fire" was most important in bringing down an airraft, especially a heavy 4-engine bomber. (Weight of fire is defined of course, as getting the heaviest weight of shot possible, in the shortest possible time, fired at the target.) Thus the ME-262 was armed with the 4 x cannon in the nose since it was designed as a bomber killer (despite Hitlers odd insistence that it carry bombs, costing the career of more than one luftwaffe officer who argued against this idiocy - "The smallest infant can see this is a fighter, not a bomber!") After awhile Hitler relented, too late for the Me-262 to do much good at doing anything but staving off defeat for a few weeks.

    Anyway the Americans seemed to have good results with the choice of either 4, 6 or 8 50 cal brownings (mounted in the nose of the P-38, and in the wings of the Corsair, the mustang, and the thunderbolt). Neither the Germans nor the Japanese ever had a weapon quite as good as John Browning's remarkable machine gun (still in use today, almost unchanged!). Having all those machine guns in the wings gave very good reliability since if one or even two jammed in flight, you still had several more to shoot back with. Contrast that with the armament of say, the early ME-109s: 1 x 20 mm cannon in the nose, and two dinky 7.92 machine guns atop the engine. If all 3 were working you had some serious firepower, if you lost any of the above you might have been at a serious disadvantage in a dogfight: the machine guns fired only a rifle caliber round, and the cannon fired a slow but heavy projectile but with relative low velocity. Should either the cannon or machine guns jam, you were instantly out gunned by almost every allied fighter in the sky.

    Almost every German bomber used the MG-34 as defensive firepower and you have to wonder what they were thinking. In the stuka it had two in the wings and later on two cannon, but one Mg-34 was set up for the rear gunner. The effectiveness of one little old 7.92 machine gun, against an attacking fighter, seems almost laughable (unless you were the rear gunner, of course). The germans had some very good rheinmetal 20 and 30 mm cannon installe in their fighters. But if i had been Jeschonnek or Goering, or someone else in charge of Luftwaffe ordnance, the first thing i'd have one was adopt a 50 caliber size weapon for aircraft use - and take out the almost useless rifle caliber machine guns out of the airplanes!
     
  5. TiredOldSoldier

    TiredOldSoldier Ace

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    Suggest you get yourself a copy of Tony's book ;) his research is impressive and while some of his conclusions are hotly debated, (see T.A. post for a sample of this) he makes some very good points.

    1) Only the Me109F had the armament you described (and the MG 151 was a high velocity weapon) the E had two 20mm and two MG17 and the G or later two 13mm MG 131 and one cannon. (This is not counting additional guns added for bomber interception on most G6).
    2) AFAIK no german planes used the MG 34, the 7.92 weapons they used were the MG 15, MG 17, MG 81 and 81Z.
    3) Had rifle caliber ammo been that ineffective the Germans would have won the Battle of Britain as pracically no British fighter of the time had anything else. Also most British bombers had rifle caliber ammo until the end of the war and the standard British 7.7 was probably a less powerful round than the German 7.92 v-Munition. The Japanese achieved their early victories with most of their fighters having only two 7.7mm weapons (the cannon armed A6M are the exception to the rule).

    German fighters as a rule are smaller than allied ones, so the Germans preferred nose mounted weapons to massive and heavy multiple wing installations. The Soviets, also with rather lightweight planes, went the same way. The Browning is heavy compared to it's performance, 29Kg compared to 17 for a MG131 and 60 for a MK108.
     
  6. Butts

    Butts Member

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    ^^^ Good post

    My pick of fighter armaments is the 20mm cannon.
     
  7. Erich

    Erich Alte Hase

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    might be wise to look further into the variety of fuzes in the LW arsenal. the 3cm came in a self-destruct fuze, hit and explode on impact, the recent purchase I mad of a 3cm M-GeschoƟ box indicates the 3cm M round in this case had a NON destruct fuze indicating the round would enter into the fabric of an Allied fighter/bomber and then explode causing great havoc within, so in answer of sorts to T.A.'s excellent posting yes this would be a nasty frag effect, tearing the insides and all whom close enough to shreds.
     
  8. wokelly

    wokelly Member

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    The 262 was delayed due to engine shortages, not Hitlers insistence on it being a bomber, though he did want it to be a fighter bomber regardless for a time.
     
  9. brndirt1

    brndirt1 Saddle Tramp

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    I just ran across a bit of information I was unaware of. The .30 caliber Brownings used in the air planes was a lightened version of the one used by ground forces. And as such had a much higher rate of fire. 1200 rounds per minute as opposed to under 700 rpms for the other types.

    1200 rpms is a very high rate of fire, and even compares favorably with the famous MG-42.
     
  10. TiredOldSoldier

    TiredOldSoldier Ace

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    Figure I have are:
    1150 RPM for the .303 Browning
    1000 RPM for the MG 15
    1200 RPM for the MG 17
    1600 RPM for the MG 81
    2800 RPM for the twin barrelled MG 81Z

    Apparently air mounted rifle caliber MGs had higher ROF than weapons designed for ground use. Maybe the higher ROF was because they didn't have the overheating needs of ground weapons (plenty of cold air flow available) but rather the opposite, (oil freezing especially in wing mounted guns).
     
  11. brndirt1

    brndirt1 Saddle Tramp

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    The Browning people not only lightened the barrel due to the cooling of the high-speed air and altitude, they also reduced the mass of the receiver so that the higher ROF could be attained, and reliability maintained. I think (don't count on this, it is from memory) they were the Browning M28 A2 models. I look around for a reference or something if you like.
     
  12. TiredOldSoldier

    TiredOldSoldier Ace

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    I had assumed that in "lightening" the receiver or the some other moving part was invoved as those are the components that will give you a higher ROF, lightening the overall gun will not have that effect but better cooling may allow higher ROF without jams. AFAIK the post war MG42 copies had both light bolt (>1200 RPM) and heavy bolt (700 RPM) versions with identical weapon weight.
     
  13. brndirt1

    brndirt1 Saddle Tramp

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    Yes, as I understand the process the barrel thickness itself was reduced, and the bolt and receiver "box" were lightened as well in the A2 "aircraft" version. This made the barrel and the overall weight of the weapon lighter, and more "compact" for fitting in confined spaces of wings I guess. That version was also (I think) ambidexerous, loading from either side as needed for feeding, left feed for left-hand wings, right feed for right-hand wings.
     
  14. T. A. Gardner

    T. A. Gardner Genuine Chief

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