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

Hi:

I have read that sometimes, some FW190 pilots had the outer wing cannons of their planes removed to save weight---especially with earlier marks of FW(A2 thru A5), where the outer cannon was the older MG/FF with a very different ballistic performance that the MG150/20 of later FW marks; So...how much weight did this actually save & how much of an improvement did it make in the performance of the FW? I imagine the reduction in firepower was moot, given that MG151s were much harder hitting & had a higher velocity & rate of fire;

Thanks, ahead of time;

NickM

FW 190 outer wing cannons
 

Hi Nick

I remember reading a post on this discussion board by George Hopp in which the specifications of a Fw 190 A-4 with and without the outboard MG FF cannons were compared. If I recall correctly, the weight difference was 100 kilograms and the maximum speed without the guns was raised by 10 kph (no idea on what altitude this was at nor the effect on the climb rate). However, it would be nice to check with him or somebody else with available information before accepting this, as there were so many different variables involved (including my memory!).

Horrido!

Leo

Re: FW 190 outer wing cannons
 

Weight does not influx horizontal speed, so if there was speed increase, it was due to better aerodynamics of the cannon-less wing rather than of any weight savings. Parameters that improve are climb rate and roll rate, quite likely the aircraft was also nicer to handle.

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

Interesting question - here is sme additional information you may find helpful and may prompt someone to fully answer your question.


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

2) MG 151/20 Mauser 20mm weighed 42 kg and fired 630/720 rds/min 100 rds weighed 19.9 kg

So you could save about 150 kg for x2 MG FF if you remove the weapon and what ever bracket it was mounted with. (just a guess)

Cheers

John

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

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

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

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.

:o Sorry for my english

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

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

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

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...

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

It was always a 60-round drum, but may have been loaded with only 55 rounds to improve feed reliability. Some time in 1942 (IIRC), a 90-round drum with the same external dimensions was introduced.

Tony Williams: Military gun and ammunition website and discussion forum

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

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

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

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.

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

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

xxxxxx
Pardon?

Wondering...
 

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?

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

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

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

It may not be obvious, but the reason why weight does influence speed is quite simple.
Adding weight to a specific plane means, that this plane has to achieve more lift to stay in in level flight. More lift with the same wing needs a higher angle of attack of the air flowing around the wing. And a higher angle of attack does produce more drag.
The speed advantage by using less weight is dependent on the aerodynamic efficiency of the plane. The speed advantage with a 2 percent lighter "Me 323 Gigant" will probably be much smaller than with a "Mustang" for example.
Regards
Robert

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

"I have read that sometimes, some FW190 pilots had the outer wing cannons of their planes removed to save weight---especially with earlier marks of FW(A2 thru A5), where the outer cannon was the older MG/FF with a very different ballistic performance that the MG150/20 of later FW marks; So...how much weight did this actually save & how much of an improvement did it make in the performance of the FW?"

Sorry I didn't get onto this sooner. The weight of the outboard MG FF/Ms was 135kg (Waffen 98kg plus Ammunition 37kg) (from Rodeike's "FW Jagdflugzeug", page 147). Sorry, no info yet on speed loss, or maneuverability gain.

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

The guns by themselves didn't weigh anything like that much - the 'Waffen' weight must include associated equipment, presumably to do with mounting the guns.

Tony Williams: Military gun and ammunition website and discussion forum

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

For a WW2 fighter at maximum speed, the lift-induced drag will only be some 10-15% of the total drag. If the 200kg weight increase was 5% of the weight of the fighter (What is the weight of an Fw.190?) , then you are looking at 5% of 15%, or less than 1% increase in total drag. As drag is proportional to speed squared, so you will get no more than 1% change in top speed. This comment appears to be supported by the FW estimate quoted above.

A difference of 1% is less than that expected between adjacent aircraft off the production line, or from consecutive flight trials, and is about the measurement accuracy of the time. This is the background to arguing that weight does not affect top speed. Strictly speaking, yes it does. Practically speaking, it does not.

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

yes tonny you are spot on.
however i think that only includes what you could actually remove.
This is for both guns and both drums wich were 90 round drums.
those figure are comming from the A5 maintenace manual.teil 0 page 11 on the december 43 revision of the manual replacing the august 43 version.

if you are interested I think I have a break down of the different element (in weight document on the F and G from FW, it is in the simthoniams)


if you read the A1-A4 manuals or the report on the captured derated A3 handed over by Faber the weight of the ammo for the 60 round drums is 29 kg.(this is with 55 rounds)

philippe

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

The RAE report on 5313, which can found summerized in the Swanborough/Green book on the 190, says 57kg for 2 MG FF cannons and 41kg for the ammo and mags.

I have also seen it claimed that the 115l aux tank was often removed to save weight in fighters but that the fighter-bombers kept it for some reason.

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

"The guns by themselves didn't weigh anything like that much - the 'Waffen' weight must include associated equipment, presumably to do with mounting the guns."

You're right, Tony, the basic MG-FF with EA-FF, ZVKS-FF, DS-FF, and EPD-FF weighs only 28kg (from the handbook of 1939, reprinted in October 1940). But, I imagine, that you also need to take into account the weapon mounting and its wiring and firing indicator, as well as the air bottle with its mounting and plumbing.

I have found no speed loss yet for the mounting of the MG-FFs in the Fw 190. But, I have a report on the difference in speed for a Bf 109E-3 with and without its wing-mounted MG-FFs. The difference was considered as Zero. There were 4 test flights, which gave the following results: 31.1.39 w/o 467 km/h, 8.2.39 w 467 km/h, 15.2.39 w/o 467 km/h, 16.2.39 w 466km/h. When the MG-FFs were removed, the openings in the wing leading-edge were covered.

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

"The RAE report on 5313, which can found summerized in the Swanborough/Green book on the 190, says 57kg for 2 MG FF cannons and 41kg for the ammo and mags."

I think that the weight stated for the cannons, was for the cannons alone, since each weighed 28kg, without taking into account all the ancillary equipment that the cannons needed to function. These would include the mountings, the wiring, the hot-air ducts, the cockpit rounds counter, as well as the air bottles with their plumbing.

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

Just to add a bit more to this to for those whom want it:


MG FF/M Gewicht 28 kg Gewicht Trommel mit 60 Schuss 20,3 kg
(page 436 Peter Rodeike's book)

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

Would the 'black men' go to all the trouble of removing all the ancillary equipment?

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

"Would the 'black men' go to all the trouble of removing all the ancillary equipment?"

It probably depended on the pilot. But, sometimes they would go to great lengths to increase the capability of their a/c, including stripping out everything that added weight, polishing the a/c for more speed, installing rear-view mirrors, and telescopes. So, they might or they might not.

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

Having viewed several gun camera films showing FW190s suffering fatal damage resulting from explosion of the outer wing cannon ammo bays, I think I can see a reason why they would remove them.

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

Removing weight would have more of an impact on climb and maneuverability than top speed. For example, the lightened "Gypsy Rose Lee" version of P-40F only flew 4 mph faster than the standard version, yet more than a thousand (IIRC) were produced which saw heavy action in North Africa.