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Bf 109 propeller hub guns

Discussion in 'Aircraft' started by Poppy, Jun 15, 2010.

  1. Skipper

    Skipper Kommodore

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    Glad we can help . I suppose you have heard of the regular Schräge musik , behind the cockpit (of the Ju88 or BF-110 mainly) and oriented 45° to the rear . This device was used by Nightfighter and was feared by allied bombers as the fighters could get them from beow in a dead angle and shoot them down in a single burst.
     
  2. Skipper

    Skipper Kommodore

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    My mistake, 13mm is correct for the Mg131:)
     
  3. Poppy

    Poppy grasshopper

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    Yes, i've read about the jazz music installation. Upon looking @ the listing for the Ju88, there is a note for a C-6b model which had 2 20mm " firing obliquely upwards in schrage music installation ". Found no mention of a Nashorn config. ... Was any gun firing upwards a schrage music? Were they always mounted aft of the cockpit? Maybe the nashorn was labeled as such because guns were fitted in front of cockpit? ...Also see a Ju88 with a jettisonable 75mm gun .
     
  4. Erich

    Erich Alte Hase

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    the c-6 was experiment and so was the R version NF of the Ju 88 for the 2cm SM installation. A few A/C were fitted and that was it there was no standard until the G series crates. the nashorn is a field modification only not done up at the factory.
     
  5. Skipper

    Skipper Kommodore

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    I would even add a very small scale field modification, possibly only done on johannes Strassner's Ju.
     
  6. Erich

    Erich Alte Hase

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    yes most likely and the G-1's in NJG 2 were not fitted SM as standard equipment either, the useage of the forward 4 2cm was still the go.

    lets remember to that not all SM's were angled at 45 degrees this was pre-set to the pilots wishes in the field from 40- 65 degrees as general rule of thumb.
     
  7. efestos

    efestos Member

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    ¿? The Dewotine 520 and the Morane Sauliner 406 had the Hispano Suiza. A clasic "V" engine with a 20 mm main gun firing through the propellor hub.

    Hispano Suiza and Hispano Suiza 12Y

    The Dewoitine D.500 had that configuration. Many of them were sold to the Spanish Republica but the French goverment stopped their exportation to protect the "secret weapon".
     
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  8. Skipper

    Skipper Kommodore

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    the Dewoitine 520 was a fair airplane in 1940 and could match the Me-109, too bad so few were built, the Free Poles who flew them in June 1940, were particulary happy to score with the gun firing through the hub and shoot down Germans who thought they were facing the slower and obsolete Morane.
     
  9. Skipper

    Skipper Kommodore

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    It is a French invention from WWI by Hispano Suza and copied by the Germans in the 1930s

    Dewoitine D.520 - Wikipedia, the free encyclopedia
     
  10. Poppy

    Poppy grasshopper

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    In "Dogfight - The Greatest Air Duels Of World War ll" by Tony Holmes . Osprey 2011: It says of the Bf 109E-3 "This version of the Daimler-Benz engine could mount an MG FF 20mm cannon on it's crankcase, the weapon in turn firing through the airscrew hub. However, the problems of vibration, seizing and overheating that had beset the engine-mounted MG FF in the Bf 109-1 persisted, and the weapon was rarely used in frontline service....So it seems passing air (gas-lol) is not enough to cool guns heat.....

    Also the reason early marks of Spitfire cannon jammed was because of combat maneuver where the casing would fall back into the action....Kinda like when the carburetor float would cause fuel starvation because of negative G.
     
  11. Vanir

    Vanir Member

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    I had a great write up-correspondance with an ex-Condor L. armourer back in about 98 I think, but it's gone from the web, I haven't been able to find it.

    Anyways it was written up so somebody might know of it from my description. He talked about the armaments configurations during Me-109 early development, specifically the motorguns. They actually tried a prototyped MG-131 prior to the MG-FF in one of the BF-109C prototypes I think it was. Anyways what they were after was a gun specifically designed to be a motorgun, which the MG-FF definitely wasn't.
    The main reason was overheating, which jammed the gun. But the main reason it was recommended was by the pilots, not the crew chiefs, because the pilots liked the firepower and accuracy even if you only got 10-20 shots out of it on an average day.

    They tried wing mounted MG-FF at the same time, but everyone liked the motorgun. This translated later to the 109F configuration of a motorgun, despite Galland's protests. The real truth behind that was however, that Messerschmitt never designed his fighter for wing guns and didn't want them, and secondly that it was always designed to have a heavy motorgun, a-la new French monoplane interceptors and their soviet followers (klimov is essentially a licensed hispano-suiza). This was an initial specification by the design team, but when a heavy motorgun wasn't available the RLM wanted wing guns.

    As far as quite a few research teams I've been involved with have been able to determine, no E-3 were operationally using motorguns by mid-1940. It is possible early series versions built around Feb, could've, but it is equally likely they were disabled, left unarmed, or outright removed in the field. It didn't work.

    Even the light early series wings didn't like the relatively soft recoil of the MG-FF, which is a very soft recoil gun for its class. Pilots described it as "like each round makes the wings shake and seem they're about to break off," they were apparently very disconcerted about it in the C prototype that trialled them. One Mölders I think, remarked that their innacuracy was from shaking the wings so much.



    Ah...and as I recall, the interesting point that was gained from the Spain Me-109 configurations trials, was that a heavy machine gun of around 15mm was best to use as a motorgun for the type. This funded the MG-151 calibre, which was designed from the start to be a Luftwaffe motorgun. It was pilot protest which had it rechambered for 20mm.
     
  12. TiredOldSoldier

    TiredOldSoldier Ace

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    The reference to experiments in Spain with a "prototype MG 131" are interesting, IIRC there is a relic from the Civil War in a Spannish museum believed to be a prototype MG 151, a very different design from the MG 131, but it came from the wreck of a Do 17e not a Me 109C. Tony Williams refers to Spannish trials of the He 112V5 with a 20mm MG C30/L (whatever that is) in the hub, and some MG FF wing cannon armed He 112B serving during the last months of the civil war.
    Seems logical the Germans would experiment with .5 caliber weapons after seeing the good results the Italians got with theirs in Spain.
    The big advantage of nose mounted guns is they need no "harmonization" calibration, they also benefit from a much more rigid mount than a lightly built wing, so less recoil induced vibration and more precision.
     
  13. Vanir

    Vanir Member

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    Actually, and admitedly I've been stretching my memory a bit here because at the time it wasn't a specific point of research, it was just something I happened upon and thought was interesting...
    but anyways I think I surmised that it was an MG-131 prototype and he said simply a heavy calibre machine gun being prototyped at the time for a main fighter armament. I just couldn't think of anything else it could've been but honestly Tony Williams would know much better than me about any of this. Essentially what I'm trying to do is remember visually what he wrote on the page so I can quote specific things he said, it's kinda tricky and I'm kinda fallable.

    This has happened a couple of times. I got mates with a Czech MiG Fulcrum field mechanic who told me so much awesome stuff that hardly anyone knows, but it's so tricky and scary trying to tell people about some of the stuff he said, because if I get even the tiniest thing wrong, my whole credibility is shot, I found it's very important to just remember specific sentences he said, and just repeat those. But it's not like I've never misremembered something, and recanted/revised a dozen times before I got it right.

    this is like that, and this was a while ago, if anything I said made tony wince, I'd go with his opinion over my memory any day of the week.

    Actually TiredOldSoldier, I do remember having brought this up with Tony, the specific article I was talking about because I was asking about the MG-FF recoil. From the article I thought it had a terrible recoil, it said that when the MG-FF were first tested in the wings (which happened a few weeks after the motorgun test, which was a heavy calibre machine gun first, upgraded from the MG17 and then the MG-FF), "its sledgehammer recoil felt like it was going to rip the wings off" was apparently the comment of the pilot, and that it threw shells all over the place.
    But Tony explained how the MG-FF actually has a very soft recoil, among the best in its class.
    So I did some running around and found there were troubles putting guns in the 109 wings at first as it was, primarily because they were designed with the intention that guns would be on the centreline and never placed in the wings, that was simply how Mr Messerschmitt designed it. It didn't flex well for guns, there wasn't good space for them without moving the main gear a little. They moved CoG rearwards. You had to cut some ribs to fit them, which weakened wings that were already designed to be conservative with weight.

    So it wasn't that the MG-FF had a heavy recoil at all, the early wings were just too weak for them (emils got more ribs but the friedrich was the one that was strengthened and redesigned, and even so guns were removed).
     
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  14. TiredOldSoldier

    TiredOldSoldier Ace

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    It's quite possible that the Germans were experimenting with both .5 and light cannons in Spain, so predecessors to both the MG 131 and the MG 151 could have been tested there. The Italian fighters used a .5 weapon, and they believed that gave them an advantage over the rifle caliber MGs of the I-53 and early I-16, so the Germans could have tried something like that as well.

    BTW found this on the MG c/30L (it was in Tony's book I just had to look harder) Caliber: 20 × 138B mm
    Weight: 64 kg
    Shell : 119 g
    ROF : 350 RPM
    Muzzle velocity: 900 m/s

    Pretty impressive stats compared to the MG FF
     
  15. phylo_roadking

    phylo_roadking Member

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    As an aside - the Allies DID have a fighter flying with an inverted-V motor...the lightweight Caudron C.714 Caudron C.714 - Wikipedia, the free encyclopedia But the designers didn't attempt a through-the-hub cannon'; they'd built the C.710 prototype with Hispano Suiza cannon in underwing gondolas...but had reverted to twin MGs in each gondola for the "production" C.714.

    If cannon in the wings could give the Spitfire recoil-generated instability problems at first - I hate to think what it did to the lightweight, underpowered Caudron!!!
     
  16. Vanir

    Vanir Member

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    I liked reading once some reasoning for the inverted vee requirement for German inlines, the idea which worked was streamlining and pilot view. You could put the cockpit a little closer to the leading edge for better forward-down view (you had no forward-down view in a Spit which was one of its biggest complaints, gigantic wings in the way), and secondly the vee motor heads, where the motor is widest fits snugly right into the wing root fuselage blend, removing half the engine from the plane's frontal mass where wind resistance is concerned. Probably why the 109 maintained excellent climb and dive characteristics throughout the entire war, even in underpowered, overweight configurations it could climb and dive with Tempests or the very best of anything right to the end.
    Of course the trade off was no cockpit width, german planes like small pilots. Was always told that when I was a kid.

    Soviets loved motorguns too, I supposed this happened because of the klimov - hispano relationship. Even the ShVAK is loosely based on the french 20mm from what I understand. When they started producing rechambered Beresins in 45 they put two or three in the nose of Yaks, in this layout the USAF comparatively tested it up against the Mustang at Wright-Patterson, from some captured NK models. These were identical to those produced in 1944, they just had the Beresins. Wright field rated them as "equivalent to the P-51D in all respects, at all heights except more manoeuvrable."
     
  17. harolds

    harolds Member

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    Regarding the jamming of the ME 109's centrally mounted guns. Actually they were less prone to jamming in a well coordinated turn or a roll because of their centerline position. Wing mounted guns on the wing that was on the outside of a turn had far more g-forces on them.
     
  18. Vanir

    Vanir Member

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    Isn't there a G-restriction on the Oldsmobile gun in the Airacobras (the 37mm)? I'm pretty sure I read it jammed unless you had next to no G when firing, that's on the centreline. Maybe it's as much to do with gun type, action or something, geez I dunno, I'm out of my depth getting too technical with guns. I know Spits had problems with early Hispano fitment but I thought that was to do with feed and heating.
    I don't think they had any problems in the later fitments on any fighters. Hurris, Tempests, Spit IXc/e all seemed to be just fine using the guns during BFM.
     

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