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Aircraft armor

Discussion in 'Aircraft' started by harolds, Jul 20, 2016.

  1. harolds

    harolds Member

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    Aircraft of the WW2 era had two types of armor: steel and glass. I'm sure as the war went on the armor plate was strengthened. German fighter windshield glass was about 90mm thick by the end of the war. However, I have yet to read anything about how effective these armor plates (steel or glass) were. I'm sure they could stop rifle-caliber bullets but how effective were they on the larger cartridges that came out as the war progressed? I've done some research on line and I can't seem to find an answer. Can anyone help here?
     
  2. GunSlinger86

    GunSlinger86 Well-Known Member

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    American fighters were built like tanks, how were the US fighters compared to German fighters in armor and protection?
     
  3. CAC

    CAC Ace of Spades

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    back armour built to take 20mm...
     
  4. mcoffee

    mcoffee Son-of-a-Gun(ner)

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    The document "A Study of Ballistic and Metallurgical Characteristics of Steel Aircraft Armor" (1948) can be found here:

    http://www.dtic.mil/dtic/tr/fulltext/u2/492302.pdf

    The file is too large to post in this thread, but it should provide some insight to your request.

    It gives typical resistance to penetration by 1943 as follows [pdf page 98]:

    1/4" plate vs. .30 AP @ 0° and 1975 fps
    3/8" plate vs. .50 AP @ 0° and 1825 fps
    1/2" plate vs .50 AP @ 0° and 2075 fps

    Also, a 1943 document related to armor testing
    http://www.dtic.mil/dtic/tr/fulltext/u2/a953654.pdf


    Have not found equivalent for armored glass...
     
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  5. harolds

    harolds Member

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    Thanks mcoffee for those two scientific studies. They are basically studies as to what type of armor is best for use in aircraft. I found it interesting that weight for weight, duralumin is often superior to homogenous steel in resistance to projectiles. Also interesting was the fact that many types of armor plate became brittle at low temperatures and cracked when hit. Since much of the air fighting in WW2 was at high altitude with the corresponding low temps, it could be that the high altitudes contributed to a projectile over-matching the armor. Also suggested was that perhaps much armor was successful in defeating projectiles because when the projectiles hit the aircraft skin and especially structural members, the AP projectiles yawed or tumbled and did not hit the armor point on. Also of note, the first study mentioned that sometimes these armored plates would spall on the back sides with enough force, or by explosive shells, that the flakes could cause injury or death to the crewman behind it.

    However, I still haven't gotten a good idea of how effective these plates were in saving the lives of the men behind them. Naturally, there are a lot of variables that come into play in any battle situation, but nothing so far as to how these armored plates worked when absorbing punishment from real opponents guns. One would think some studies would have been done by all air forces to check downed aircraft to see if what's effective and what wasn't. As you said, there's very little on armored glass (which is actually not glass but a polycarbonate).
     
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  6. Poppy

    Poppy grasshopper

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    Great thread, Harolds.
    The crews also wore armour plates in their flack jackets. Wonder if it was the same type of plate used in the protection of the aircraft.
     
  7. harolds

    harolds Member

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    I was perusing the "Fighter Gun Debate" website and noticed it had a section on armor. The Brits said theirs would stop a 20mm but I'm not sure if that meant to early FF cannon or the later Mauser round that was considerably more potent.

    The USA proofed their seat armor to best the 50 cal. ball round. Sounds like it could have been defeated by AP rounds, both the 50 cal. and 20mm Mauser bullet.

    Germany proofed their armor to defeat the American 50 cal. at normal combat ranges, which only makes good sense.

    Nothing much is known about the Japanese armor.

    As far as glass armor, the site couldn't add much one hit could probably wipe out most of your forward vision.
     
  8. Poppy

    Poppy grasshopper

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    Did the plates spall ?- remember something about flak curtains but could only find this with duckgo



    flak curtain


    noun



    Definition of flak curtain




    1. : flexible steel mesh or plates covered with canvas and used in military aircraft to protect vulnerable areas from enemy gunfire
     
  9. harolds

    harolds Member

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    Hmmm...never heard of a "flak curtain" before. Might be useful against shell splinters all right. I'm sure some of those armor plates spalled but those pieces of spall had to go through a lot of heavy clothing in order to get to the pilot. Doubt they could do that and still have enough energy to penetrate a body.
     
  10. Kai-Petri

    Kai-Petri Kenraali

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    I don´t know if the Germans had other plans to strengthen their planes but against the B-17´s they had plans as the Sturmböcke:

    The Fw 190, designed as a rugged interceptor capable of withstanding considerable combat damage and delivering a potent 'punch' from its stable gun platform, was considered ideal for anti-bomber operations. Focke-Wulf redesigned parts of the wing structure to accommodate larger armament. The Fw 190A-6 was the first sub-variant to undergo this change. Its standard armament was increased from four MG 151/20s to two of them with four more in two underwing cannon pods. The aircraft was designated A-6/R1 (Rüstsatz; or field conversion model). The first aircraft were delivered on 20 November 1943. Brief trials saw the twin cannon replaced by the MK 108 30mm autocannon in the outer wing, which then became the A-6/R2. The cannons were blowback-operated, had electric ignition, and were belt fed. The 30mm MK 108 was simple to make and its construction was economical; the majority of its components consisted of just pressed sheet metal stampings. In the A-6/R4, the GM-1 (nitrous oxide) Boost was added for the BMW 801 engine to increase performance at high altitude. For protection, 30 millimetres (1.2 in) of armoured glass was added to the canopy. The A-6/R6 was fitted with twin heavy calibre Werfer-Granate 21 (BR 21) unguided, air-to-air rockets, fired from single underwing tubular launchers (one per wing panel). The increased modifications, in particular heavy firepower, made the Fw 190 a potent bomber-killer. The A-7 evolved in November 1943. Two synchronized 13mm (.51 caliber) MG 131 machine guns replaced the twin cowl-mount synchronized 7.92mm (.318 cal) MG 17 machine guns. The A-7/R variants could carry two 30mm MK 108s as well as BR 21 rockets. This increased its potency as a Pulk-Zerstörer (Bomber Formation Destroyer). The A-8/R2 was the most numerous Sturmbock aircraft, some 900 were built by Fiesler atKassel with 30mm MK 108s installed in their outer wing panel mounts. While formidable bomber-killers, the armour and substantial up-gunning with heavier calibre firepower meant the Fw 190 was now cumbersome to maneuver. Vulnerable to Allied fighters, they had to be escorted by Bf 109s.

    https://en.wikipedia.org/wiki/Focke-Wulf_Fw_190_operational_history

    Shown on the picture are the additional outer armour of the "Sturmböcke". It consists out of 30 mm thick plates of bullet-proof glass at the windscreen and as so-called "blinders" mounted on the hood. In addition there are 5 mm thick steel plates screwed under the cockpit and the windscreen!
    The pilots disliked the Blinkers because of the reduce sight, so later on many was removed by the flight personnel.



    http://rafiger.de/Homepage/FBMuseum/Info-JG3Udet/Info-JG3-Udet.htm
     
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  11. Markus Becker

    Markus Becker Member

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    About 20mm projectiles. They are not bullets but shells. They explode on impact. If an armor plate that remains intact after being hit matters little if at all. They force of the explosion rips a chunk out of the plane. Do that a couple of times and the plane is littlerally falling apart, even if the armored parts have not been penetrated.
     
  12. harolds

    harolds Member

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    I'd split the difference with you Marcus. If they carried high explosive as their destructive force, then indeed they'd be shells. If the 20mm cannon round is what we call "ball ammo", then I'd say it could be called a bullet. AP projectiles could even be called "shot". A small quibble, we all know what we're talking about here.

    "A couple" of HE 20mm HE rounds wouldn't necessarily cause even a fighter plane to come apart unless something like a wing spar was hit. Now a 30mm HE hit from a Mk 108 cannon is a totally different story!
     
  13. phylo_roadking

    phylo_roadking Member

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    A hit on armoured, high lead content glass won't craze it IIRC. Chip it, but not craze it.

    There was a study done early in the war on the rear seat armour of the Blenheim for the RAF, comparing RAF .303 MkVII rounds with German rifle-calibre equivalent....conventional and the steel cored AP rounds. The Blenheim carried very light armour IIRC...but unless the rounds hit a frame member, the actual thin skin of the aircraft didn't do much at all to slow down the rounds. IIRC the results showed that the .303 round penetrated better than the German equivalent - but the steel cored German round penetrated better.

    Turned out in later searching that for the first few years of the war each landser carried ten of these AP rounds as part of his standard load out, as his individual contribution to carrying AP ammunition for the squad MG34...which is why you read accounts of that weapon sometimes firing AP ammunition. For example, on Crete.
     

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