What were the weight savings from removing FW 190 outer wing cannons?

[Tony Williams]

Originally Posted by John P Cooper

1) MG FF: Oerlikon Schweiz 20mm weighed 37 kg and fired 530 rds/min 100 rds weighed 33 kg (drum) or 21 kg (belt)

Ermm - the Ikaria-made MG-FFM weighed 26 KG and it never had belt feed (apart from an electric-powered device in some night fighters).

Tony Williams: Military gun and ammunition website and discussion forum

["bubi"]

Hi,

This operation which consists in reducing the weight of "jäger" in order to make it more powerful face to the enemy fighters was still in 1944 on more advanced marks like FW 190 A-8.

Sorry for my english

[Leo Etgen]

Hi guys

Interesting discussion. I am glad that others are responding to this question as I find it interesting as well. I would just like to point out that all sources that I have seen state that the Fw 190 series used a 55 round drum for the MG/FF, although I have also read about a 60 round drum that may have been used as well. On the post that I mentioned earlier I recall that the maximum speed was 646 km/h without and 636 km/h with the outboard guns. However, what configuration this aircraft, apparently a Fw 190 A-4, was in when tested, whether it was equipped with a bomb rack (s), the engine condition, other equipment fitted, etc. I do not know. I believe these were the results of a German test so it was not captured equipment. I would assume that the fairing over of the gun ports and deletion of the underwing bulges, like Franek points out, would contribute in no small measure to any increase in speed.

Horrido!

Leo

[John P Cooper]

Err the belt fed was experimental (due to mag capacity and jamming but I am not 100% sure maybe some experten can comment) sorry it was only added as a weight comparison...

[Tony Williams]

Originally Posted by John P Cooper

Err the belt fed was experimental (due to mag capacity and jamming but I am not 100% sure maybe some experten can comment) sorry it was only added as a weight comparison...

Yes, they made a rather Heath Robinson attempt at a belt feed, but I doubt that it was ever installed in an aircraft. The only people to produce a successful belt feed for the aircraft Oerlikon were the Japanese.

Tony Williams: Military gun and ammunition website and discussion forum

[Jens]

Indeed weight does very slightly (up to 1% for 200kg) influence maximum speed.

For D9 german Documents show an decrease of perfomance by 10km/h, 0,45m/s climb and 150m height, if you use mk108 rüstsatz.

[philippe willaume]

hello
The outer wing guns Affair

You have all seen pictures of FW 190 of all series with and without outer wing guns. The amount of ammunition for the MG FF varies from one publication to another and the type of guns changed from version to versions.

The guns used in the outer wing inboard position were the MG FFM, MG151/20E and MK108.

In this paragraph we will just concerned ourselves with what determined the presence of the gun in the outer position. You will find the ballistic and the effect of the weapons on the plane in the Weapon chapter.



According the version of the A there was two types of gun used the MG FFM and the MG 151/20E.

As far as the MG FFM is concerned, the part number in the production sheet never changed, save for the A1 and the Aa-3.

The MG FFM had slightly better performance than the MG FF and had the ability to fire Mine (highly capacity explosive) ammunition. See the gun section for more details.

As far as the A2, A3, A4, A5 are concerned, this was a rustsatz (optional) and it is described as

such in production sheets (except for the A1 and the Aa-3 sold to the Turks where it is part of the plane).

The manual for the A1, A2, A3, A4 gives the weight for a version with and without the outer guns. The magazine usually used is the T 60-FF with 60 rounds.

The manual for the A5 gives one the version with the outer guns and the drum with 90 rounds but precise that removing those guns will save around 1345 kg (98 for the weapons and 37 for the ammo), so it seems clear that this was still an option.

The manual for the A1-to A4 and the manual for A5 /A6 clearly states that the T 60-FF (60 rounds) could be replaced with T 90-FF (90 rounds) without any modification.

Note: the A6 used MG 151/20E in the outer position but the A5 still used the MG FFM.

Of course there is plenty of evidence where the guns were installed.



The MG 151/20E in the outer wing position is mandatory equipment, according the plane’s production sheet anyway and the manuals do not mention any removal or rustsatz.

That being said there is plenty of photo evidence where even the outer MG151/20 was removed.

In September 44, the Uk captured, a deserting ferry pilot crash-landed in England, an A8 with the TU engine. The plane was without the outer MG 151/20E. (PR0 AIR 40/151).

The weight for the outer guns 177 kg (112.6 and 64 kg for the ammo)



So far I have not being able to determine a set of rule that led to the deletion of the outer guns. These comments only concern fighter planes, Jabo (ground attack) ans Jaborei (long-range ground attack) did not have the external guns installed at all. So here the list of the case where it did happened, just bear in mind that this is just a very generic rule of thumbs.

Pilot wish, Installation of the FuG 16 ZY or more precisely the Y or E add-on to the FuG 16 Z, main mission to fight against fighter or to assume a pure fighter role, possibly some gun shortage or re-use of ground attack plane wings in fighter production line.

[Franek Grabowski]

xxxxxx

Originally Posted by Jens

Indeed weight does very slightly (up to 1% for 200kg) influence maximum speed.

Pardon?

[Dick Powers]

Maybe the real reason wasn't the weight, but the effects on the moment of inertia about the roll axis. Two 100 pound weights at mid span could have significant effects on the roll inertia, amking the FW 190s superior roll rate much less.

Also, might the recoil effect of the two wing guns firing at slightly different times effect the directional control and creat a wandering effect of the aiming point?

[Mifletz]

A "Heath Robinson" in the UK is known as a "Rube Goldberg" in the USA! = an extemporised lash-up job.

Originally Posted by Tony Williams

Yes, they made a rather Heath Robinson attempt at a belt feed