ME-110 in-line cannon?

[Ryan B.]

Probably a remarkably dim question, but why didn't bomber-destroyer 110s, and, I suppose, ME-410s, load a 20mm, or larger, cannon into the engines--a la ME-109s_-rather than sling a heavy wind resistant cannon pack below the fuselage?

[Graham Boak]

I suspect that the cannon breech and ammo tank would get in the way of the wheel well, but the earlier versions had a different version of the engine anyway.

[Jure Miljevic]

Hello

It would also mean giving away advantages of weapons, concentrated close to a center line. It was difficult enough to align cannons and machine guns to ensure close hit pattern at certain distance (and only at that distance) without cannons installed two or three meters out of center line in horizontal plain. Also, 3,7-cm and 5,0-cm cannons had significant recoil which made accurate aiming practically impossible and hits a matter of luck - even when installed relatively close to a center line as was the case with Me 410. Also, I suspect such installation would put significant strain on wing spares. Reinforcing wing structure would add extra weight to Luftwaffe Zerstörers, which were too heavy to start with. Cheers

Jure

[Ryan B.]

Thanks, gentlemen.  I don't think moving the 20mm cannon fire away from the center line would make all that much difference, particularly with a large target like a bomber, and the original centerline cannon still installed--in fact it may distribute the aircraft's punch over a wider area--but I can see your points about reinforcing the wing spars and bulking out the engine nacelles.

[Richard502]

Would not additional weight (guns and ammunition) far from the centre of gravity decrease the rate of roll? And the Bf110 was not the most agile plane to start with. As an aside, there are plenty of FW190s that had their outboard wing mounted guns removed (as a weight saving measure?); but afaik, they all kept the inboard guns despite their lower rate of fire.

Richard

[Graham Boak]

Distributing the punch would go against the principle of concentration of fire.  Whereas wing guns are adjusted so that the fire is angled to converge at a given point ahead, it is impossible to do the same for a gun mounted in the middle of an engine and firing through a extended tube.

 

I don't think that the ultimate rate of roll would be affected, but the inertias would mean that more control power would be needed to start the roll, and to stop it. Hence the aircraft would be comparatively sluggish, as described in the literature.  Yakovlev refused to put guns in the wings of his designs.

 

There's nothing intrinsically inaccurate about 37mm or 40mm cannon, or they would not have gained the recorded successes in the anti-tank role or indeed the sniper reputation of the Yak 9T.

[Ryan B.]

Some factions went against the principle of concentration of fire, particularly early in the RAF, with the Spitfire's eight guns harmonized at different distances, the intention being that new pilots would have a better chance of making a hit if their fire covered a larger area. Considering the lack of punch of the English .303s, this is a pretty foolish idea. Even so, for a large target like a bomber, fire outside the harmonization point would still have a chance of hitting the aircraft, and a 20mm cannon would have a far greater effect than a .303.

As for the wing loading and its effect on maneuverability, that would of been of little importance when attacking USAAF bombers beyond escorting fighters range. Of course, when better tanks and P-51s show up....

 

Edited February 25, 2019 by Ryan B.
initially wrong thread

[Jure Miljevic]

Graham,

Luftwaffe aircraft, armed with heavy caliber guns, were reasonably successful against ground targets but far less so against Allied bombers. Stationary or slow moving tank at 300-400 m is much less difficult to hit than a heavy bomber, constantly changing her relative position at distances between 500 to 1000 m. Also, while German BK 3,7 and BK 5,0 had decent muzzle velocity (900 and 920 m/s respectively), their rate of fire was miserable (140 and 45 rpm respectively). Their ammunition supply was meager to say the least as on Bf 110 it was Funker's job to feed BK 3,7 with six grenade clips and BK 5,0 on Me 410 carried grand total of twenty-two grenades. Pilots of the latter were expected to keep steady aim at bombers some half a mile ahead despite a massive recoil of some seven tons (according to Profile publication, not my calculation) shaking their aircraft every 1,33 second. Jams on BK 5,0 were frequent and could not have been cleared during flight. No wonder that at least one Me 410 pilot, after unsuccessful conventional attack on B-17 formation, ordered his Funker to bail out and in frustration resorted to ramming.

NS-37 on Yak-9T had muzzle velocity of 900 m/s, decent rate of fire of 250-260 rpm and a 30 rounds magazine. Given that the gun fired through propeller hub I would assume recoil must have been somewhat less disruptive. It was A. G. Kubyshkin, one of the test pilots, who said that every Yak-9T pilot should be a flying sniper and hit the enemy with the first shot. Recommended distances for opening fire on ground targets were 1000 to 500 m and on flying targets 500 to 100 m. While attacking larger bomber formation, grenades could be lobbed from distances 1000 to 1200 m, but primary aim of such attacks was ˝to brake enemy formation and affect its morale˝. I have no idea how Yak-9T fared against actual ground targets but I suspect it did not matter too much - Red Army armour and specialized VVS ground attack aircraft were perfectly capable of doing the job themselves.

Ryan B., these Kiel's claims were from early war period and his score had been achieved with regular Bf 110 armament: 20-mm cannons, 7,9-mm machine guns and bomb ordnance. No heavy caliber guns had been used. Cheers

Jure