Focke-Wulf Fw 190A/D and outer wing cannon

[paradoxguy]

I understand that some pilots of the Fw 190A-series removed the outer wing cannon for improved performance. I intuit that the primary improvements would be in maneuverability. Were there known improvements in other performance parameters--speed, service ceiling, turn rate and radius? Were any of these improved performance parameters documented, or were the improvements anecdotal?

Was pilot preference the reason for omitting the outer 20mm wing cannon in the Fw 190D-9? Did Kurt Tank determine that performance improvements without the outer wing cannon were significant enough to omit them in the Fw 190D-9, or were there other reasons for this? Decreasing a fighter's armament by two 20mm cannon (especially Mg 151's in the Fw 190A-6 and later marks) seems like a substantial reduction, especially when combating heavy bombers. However, I also realize two 13mm machine guns and two 20mm Mg 151 cannon was also a fairly formidable armament in itself, especially in comparison to the Bf 109's guns.

Thanks,
PG

 

[vanir]

Deletion of the outer wing guns on A models is anecdotal, but widely supported practise for jäger squadrons. Interesting thing, sometimes the guns weren't removed, but the ammunition was at pilot request. Those that left the factory with outer guns completely removed were jabos, though I have often read in modern publications that "several pilots liked to have the outer wing guns removed for air to air combat" and cannot attest to its voracity in a literal sense. The anecdote of ammunition removal was made by a ground crewman with JG26 iirc.

The Dora was always intended for the combined jabo role, the first prototype I believe had the A-6 wing complete with four MG151 but it was destroyed in an air raid and subsequent prototypes and production series had just two.

Of course where the intention is to mount heavy external stores less integral armament is preferred particularly with jabo types which rely on speed at low altitude for penetration to the target and successful escape. Schlacht types of course do retain a good strafing capability, so may have four wing guns with machine guns removed to save a little weight for bombs, instead of two wing guns for more limited strafing but better weight savings whilst often retaining machine guns for defence as in a jabo. An Fw in the schlacht role is likely to be heavier clean than one for the jabo role per se (ie. the jabo will be quicker, the schlacht better armed).

I believe that pilot anecdote about deletion of outer wing gun/ammunition was related to their being superfluous in aerial combat, that two MG151 and a pair of machine guns on the centreline with good ammunition stores was more than adequate (which is the jabo layout). It seems to me at this point however that in this case the ammunition of a 190A fitted with four guns was often removed rather than the outer guns themselves, unless the aircraft left the factory as a jabo option and was being used in the aerial combat role on that day.

One more point, early Fw A series, the A-3 and A-4 notably were not fitted with MG FF as often as they were. Although I've spoken to armaments experts personally about the soft recoil of the MG FF I've also read wartime accounts claiming that when fitted to the wings of an aircraft, the MG FF had "sledgehammer recoil which felt like they were going to tear the wings off, and the shots danced all around the target." This is of course also anecdotal at best.

 

[paradoxguy]

Deletion of the outer wing guns on A models is anecdotal, but widely supported practise for jäger squadrons. Interesting thing, sometimes the guns weren't removed, but the ammunition was at pilot request. Those that left the factory with outer guns completely removed were jabos, though I have often read in modern publications that "several pilots liked to have the outer wing guns removed for air to air combat" and cannot attest to its voracity in a literal sense. The anecdote of ammunition removal was made by a ground crewman with JG26 iirc.

The Dora was always intended for the combined jabo role, the first prototype I believe had the A-6 wing complete with four MG151 but it was destroyed in an air raid and subsequent prototypes and production series had just two.

Of course where the intention is to mount heavy external stores less integral armament is preferred particularly with jabo types which rely on speed at low altitude for penetration to the target and successful escape. Schlacht types of course do retain a good strafing capability, so may have four wing guns with machine guns removed to save a little weight for bombs, instead of two wing guns for more limited strafing but better weight savings whilst often retaining machine guns for defence as in a jabo. An Fw in the schlacht role is likely to be heavier clean than one for the jabo role per se (ie. the jabo will be quicker, the schlacht better armed).

I believe that pilot anecdote about deletion of outer wing gun/ammunition was related to their being superfluous in aerial combat, that two MG151 and a pair of machine guns on the centreline with good ammunition stores was more than adequate (which is the jabo layout). It seems to me at this point however that in this case the ammunition of a 190A fitted with four guns was often removed rather than the outer guns themselves, unless the aircraft left the factory as a jabo option and was being used in the aerial combat role on that day.

One more point, early Fw A series, the A-3 and A-4 notably were not fitted with MG FF as often as they were. Although I've spoken to armaments experts personally about the soft recoil of the MG FF I've also read wartime accounts claiming that when fitted to the wings of an aircraft, the MG FF had "sledgehammer recoil which felt like they were going to tear the wings off, and the shots danced all around the target." This is of course also anecdotal at best.

Thanks much for your detailed and thoughtful response, I understand better the situation about gun and/or ammunition removal to save weight for jabo and fighter sorties and that much of the "data" are anecdotal. In particular, I didn't realize that sometimes, if not more often, the ammunition for the outer guns rather than the guns themselves omitted were omitted at the pilots' request. I can see now why the centerline guns (two 13mm machine guns, two wing-root MG 151 20mm cannon) were regarded as more than adequate armament, especially with the unusually large ammunition capacities (475 rpg for the 13mm guns, 250 rpg for the wing root 20mm cannon, IIRC). Your note also answered a long-latent question for me about the Fw 190F/G-series and why their outer guns were omitted at manufacture.

PG

 

[davebender]

I have always wondered why the Fw-190 series and Me-109F and later models had machineguns at all. Why not these weapon configurations?

Me-109F and G. 3 x Mg151/20 cannon.
1 firing through the prop shaft.
1 in each wing root.

Fw-190 series. 4 x Mg151/20 cannon.
1 in each wing root.
1 in each outer wing position.

Plenty of firepower. All weapons are the same so no need to worry about different aim points. Cowl space is not taken up by a pair of machineguns and ammunition, perhaps allowing the nose to be more streamlined. Would anybody miss the machineguns?

 

[paradoxguy]

I have always wondered why the Fw-190 series and Me-109F and later models had machineguns at all. Why not these weapon configurations?

Me-109F and G. 3 x Mg151/20 cannon.
1 firing through the prop shaft.
1 in each wing root.

Fw-190 series. 4 x Mg151/20 cannon.
1 in each wing root.
1 in each outer wing position.

Plenty of firepower. All weapons are the same so no need to worry about different aim points. Cowl space is not taken up by a pair of machineguns and ammunition, perhaps allowing the nose to be more streamlined. Would anybody miss the machineguns?

You raise some interesting points about WWII German fighter armaments. With regards to the Bf 109, the space in the wing was very limited and probably would not have accomodated the MG 151 internally, even in the wing roots. Even the Bf 109E-series had difficulty accomodating wing-mounted MG FF 20mm cannon; IIRC, cutouts in the wings were necessary to fit the internal MG FF cannon and the limited space forced the use of drums instead of belt-feeds for the cannon ammunition, and even then only one small 60-round drum could be fitted for each cannon. By comparison, the engine-mounted 20mm cannon in the BF 109F/G-series carried belted 120-150 rounds and the Fw 190A/D-series carried 250 belted rounds per gun for their wing-rooted MG 151 cannon. The "gunboat" Bf 109F/G/K-series had their wing-mounted MG 151 cannon fitted in underwing gondolas rather than internally, again due to lack of space. I also recall a protoype Bf 109 that was fitted with a 20mm cannon in a central under-fuselage gondola. I speculate that if space were available in the wings, including the roots, Messerschmitt would have readily placed additional guns there instead of the external performance-sapping gondolas. I don't know if this was ever considered, but I am curious if placing MG 131 machine guns internally in the wings would have been worthwhile, given that the MG FF cannon could be shoehorned in the wings. In this situation, though, I suspect the ammunition capacity for the wing MG 131 would have been severely limited.

You may know that Adolf Galland lamented the decrease of guns when the Bf 109E-series phased out for the Bf 109F-series and ordered 1 or 2 Bf 109F's to be fitted with internal wing 20mm cannon for his use. Again, because of the wing space limits, the internal wing cannon was limited to the MG FF and not MG 151.

Obviously, the limitations of armament configurations in the Bf 109 made its cowl machine guns essential. I do not know the factors that were considered that led to the Fw 190A/D-series carrying cowl-mounted machine guns. I speculate that for the A-series, the inherently large cross-section of its radial engine provided considerable space that allowed 7.9mm and eventually 13mm guns to be installed, along with a large amount of ammunition and, since the radial engine mounting could not be streamlined further anyway and, Kurt Tank probably determined the firepower increase outweighed the weight of two cowl-mounted machine guns and their ammunition. Since the Fw 190D-9 deleted the outboard cannon, the cowl guns also became a greater proportion of the firepower. Interestingly though, in the later Fw 190D-series and the Ta 152H, the cowl guns were deleted, which appeared to coincide with the installation of engine-mounted 20mm/30mm cannon and seems to support your armament philosophy.

The Ilyushin IL-2 Sturmovik and its successor the IL-10 both carried cowl-mounted 7.62mm machine guns in addition to wing-mounted 23mm cannon. As ground-attack aircraft, the 7.62mm guns did not comprise a significant proportion of firepower, but the guns were used primarily as tracers to better aim the 23mm cannon. I also recall reading in some sources that the Fw 190's cowl machine guns were used in the same way to aim the cannon fire more accurately against the heavy bomber formations (and presumably targets in general in air-to-air combat).

I'm speculating considerably--any other opinions and thoughts?

 

[Krabat42]

Sorry, but I've never heard of a Il-2 or Il-10 with cowl-mounted machine guns (though there may have been prototypes). The series production models had all their guns mounted in the wings.
Krabat

 

[paradoxguy]

Sorry, but I've never heard of a Il-2 or Il-10 with cowl-mounted machine guns (though there may have been prototypes). The series production models had all their guns mounted in the wings.
Krabat

OOPS! My extreme bad. You're right, the machine guns were wing-mounted. Don't know what I was thinking, because I know I knew that before, must have had a brain cramp. Sorry for the confusion.

 

[Shortround6]

I have always wondered why the Fw-190 series and Me-109F and later models had machineguns at all. Why not these weapon configurations?

Me-109F and G. 3 x Mg151/20 cannon.
1 firing through the prop shaft.
1 in each wing root.

Fw-190 series. 4 x Mg151/20 cannon.
1 in each wing root.
1 in each outer wing position.

Plenty of firepower. All weapons are the same so no need to worry about different aim points. Cowl space is not taken up by a pair of machineguns and ammunition, perhaps allowing the nose to be more streamlined. Would anybody miss the machineguns?

The 109's through the prop gun used percusion primers.
The 190's wing root guns used electric primers to allow synchronization.

A 109 was tested with a single poded gun under the fuselage but the idea was not adopted. Supposedly the Luftwaffe did not want to risk having the two different ammo types in the same aircraft.
109 units got percusion primed ammo and 190 units got electric primed ammo.

Germans seemed to perfer the close grouping of guns which the outer wing guns of the 190 doesn't follow.

 

[Erich]

I'll try and make this very simple as I have covered this many times over the years on web-sites.

The later A-8 pilots with ground crew removed the outter wing 2cm due to combat with more maneuverability of the P-51, the extra cannons were not needed. four 2cm's were in place and later 3cm outboard for attacking the bombers. the pilots flying later A-8's and standard A-9's had problems dealing the death blows to the US heavies with the limited 2cm and mg 131's equipped, one reason the III. gruppe of JG 301 was designated the Schwere gruppe - to attack Bobmers only if at all possible.

The D-9 was to be used as in flight combats with US and RAF piston engine fighters it was not be used for carrying out the rear attacks on US heavy bombers, and although this was done in JG 301 as a unit I am writing a book on; their attacks were hardly felt more of a promise engaging the 8th AF Mustangs instead.

 

[paradoxguy]

I'll try and make this very simple as I have covered this many times over the years on web-sites.

The later A-8 pilots with ground crew removed the outter wing 2cm due to combat with more maneuverability of the P-51, the extra cannons were not needed. four 2cm's were in place and later 3cm outboard for attacking the bombers. the pilots flying later A-8's and standard A-9's had problems dealing the death blows to the US heavies with the limited 2cm and mg 131's equipped, one reason the III. gruppe of JG 301 was designated the Schwere gruppe - to attack Bobmers only if at all possible.

The D-9 was to be used as in flight combats with US and RAF piston engine fighters it was not be used for carrying out the rear attacks on US heavy bombers, and although this was done in JG 301 as a unit I am writing a book on; their attacks were hardly felt more of a promise engaging the 8th AF Mustangs instead.

Erich, thanks for your concise summary of the situation of the outboard cannon in the Fw 190A-8 and Fw 190D-9. I have not seen your previous posts about this topic, but hopefully I will see them as I read more forums on WWII aviation. Your posts to this forum have always been interesting and informative for me.

 

[Soundbreaker Welch?]

Thanks Erich.

 

[vanir]

I'll try and make this very simple as I have covered this many times over the years on web-sites.

The later A-8 pilots with ground crew removed the outter wing 2cm due to combat with more maneuverability of the P-51, the extra cannons were not needed. four 2cm's were in place and later 3cm outboard for attacking the bombers. the pilots flying later A-8's and standard A-9's had problems dealing the death blows to the US heavies with the limited 2cm and mg 131's equipped, one reason the III. gruppe of JG 301 was designated the Schwere gruppe - to attack Bobmers only if at all possible.

The D-9 was to be used as in flight combats with US and RAF piston engine fighters it was not be used for carrying out the rear attacks on US heavy bombers, and although this was done in JG 301 as a unit I am writing a book on; their attacks were hardly felt more of a promise engaging the 8th AF Mustangs instead.

As I mentioned Erich I've read a ground crew member clearly stating the MG-151/20e in the outer wings were left in place whilst only the ammunition was removed and it was simply due to superfluous armament, providing no truly notable increase in aircraft performance but simply that 2x MG131 and 2x MG151/20e were perfectly adequate for fighter-fighter aerial combat.

What I had absorbed from this article:
Earlier MGFFm were often removed and this was done at the factory, for the jabo role. Versions of A-6 onwards also had outer guns completely deleted at the factory, for the jabo role. But a regular A-6/7/8/9 came with four 2cm and in the field the outer guns were not removed at pilot request for increased performance, but their ammuniton boxes simply weren't filled at pilot request for reasons of being superfluous armament with lesser accuracy (wing flex and convergence issues).

I've been hunting since I saw your post and disappointingly haven't yet found the article. I've posted at LEMB since IIRC I was first linked to the article there and somebody ought to know what I'm talking about.

I mean I hope I'm not wrong, but my memory for these things is usually pretty good and this in particular had an impression on me at the time. Fingers crossed I can come back with a reference/link.

 

[paradoxguy]

As I mentioned Erich I've read a ground crew member clearly stating the MG-151/20e in the outer wings were left in place whilst only the ammunition was removed and it was simply due to superfluous armament, providing no truly notable increase in aircraft performance but simply that 2x MG131 and 2x MG151/20e were perfectly adequate for fighter-fighter aerial combat.

What I had absorbed from this article:
Earlier MGFFm were often removed and this was done at the factory, for the jabo role. Versions of A-6 onwards also had outer guns completely deleted at the factory, for the jabo role. But a regular A-6/7/8/9 came with four 2cm and in the field the outer guns were not removed at pilot request for increased performance, but their ammuniton boxes simply weren't filled at pilot request for reasons of being superfluous armament with lesser accuracy (wing flex and convergence issues).

I've been hunting since I saw your post and disappointingly haven't yet found the article. I've posted at LEMB since IIRC I was first linked to the article there and somebody ought to know what I'm talking about.

I mean I hope I'm not wrong, but my memory for these things is usually pretty good and this in particular had an impression on me at the time. Fingers crossed I can come back with a reference/link.

Vanir-thanks for the follow-up post. It touches on my original query about whether omitting or deleting the outboard wing cannon improved performance significantly. Your comments that the outboard wing cannon of the non-Jabo Fw 190A-6/7/8/9 were not removed in the field, in both your posts, as opposed to statements by other writers in addition to Erich, such as Don Caldwell, are intriguing at the very least and touch on my original question whether omitting the outboard guns improved performance significantly and in what parameters, if at all. If omitting the outboard guns did not affect performance significantly, then would it been better to retain them, such as in the Fw 190D-9, for increased firepower? However, your comments indicate that wing flex and convergence appeared to be issues significant enough to omit the ammunition in the Fw 190A-6 and later models and perhaps omit the outboard guns altogether in the Fw 190D-9.

I'm interested too if you locate the article that indicates only ammunition and not the outboard guns themselves were removed in the field.

Anyway, just some thoughts and questions that help make the topic fun, at least for me.

 

[Civettone]

109 units got percusion primed ammo and 190 units got electric primed ammo.

Why ?? I don't get the connection with the priming method and the positioning of the guns...
How did it work and what were the advantages, one to the other?

What about other AFs? What did they use??

Kris

 

[vanir]

Follow up post. Still haven't tracked down this article but I'm still looking, trust me it'll turn up...eventually. I might have it laying around my room...I've an inordinate amount of warbird stuff.

I've got some feedback at LEMB that jogged my memory a little. The groundcrewman was speaking anecdotally about an a/c he worked on himself, the article's author was asking questions about outer gun barrels being present in photos, if the barrels were left for any particular reason as the outer guns were known to have been disabled. He said the entire guns were there (for balance reasons, which doesn't make any sense but was transliterated so he may have meant something else).
But...he also said other FWs had their outer guns completely removed. I assumed he meant jabo variants, but it appears he may have been referring to a case by case basis with field disabling of the outer guns in regular fighters. There is at least one regular A-8 captured which had the outer guns completely removed...but the ammunition boxes were still present.

In any case it is my continued assumption...at this stage, that the most likely reason for the removal/disabling of the outer wing guns on FWs for fighter-fighter combat was not improved airframe performance, but simply due to the superfluous nature of the outer wing guns, which were the only pair requiring convergence (rest were on the centreline) and due to wing flex weren't all that accurate for hitting small fast moving targets anyway. In fighter-fighter combat they wouldn't be used and this was the reason, rather than any notable performance increase...although as has been posted some performance increase with complete removal (MG151 are about 42kg apiece and accessories weigh a bit), just that they were not always completely removed and performance increase wasn't the main reason, in some cases there was little.
This was the main theme of the article.

I'll keep looking for it.

 

[paradoxguy]

Why ?? I don't get the connection with the priming method and the positioning of the guns...
How did it work and what were the advantages, one to the other?

What about other AFs? What did they use??

Kris

I'll try to provide a partial answer as I admittedly don't follow shortround6's entire logic pattern; perhaps I'm just thick

Electrically-primed ammunition results in a much shorter duration between the triggering and actual firing of the gun's ammunition than percussion-primed ammunition. This improves the rate of fire of guns synchronized to fire between the propeller blades. I understood the Luftwaffe were the main proponents of electrically-primed ammunition in their MG 131 machine guns and MG 151 cannon, as they favored centerline armament and thus synchronized guns, and electrically-primed guns had a lower loss of rate of fire when synchronized than percussion-primed guns. Using electrically-primed ammunition, the rate of fire of synchronized MG 131 and MG 151 guns was only 10% less than their non-synchronized counterparts. I understand that the US air force in WWII used percussion-primed ammunition and thus the Browning machine guns firing rate dropped approximately 40% when synchronized. I'm uncertain about shortround6's contention that the Bf 109 used percussion-primed ammunition, unless perhaps he is referring to the MG 17 machine guns used in BF 109 versions prior to the Bf 109G-5--again I could be simply thick and need some edification. I understood all MG 131 and MG 151 fighter guns used electrically-primed ammunition, but of course I could be wrong.

If you haven't seen the article on WWII fighter armament by Tony Williams, et al, it might be a useful reference:

WORLD WAR 2 FIGHTER GUN EFFECTIVENESS

 

[Civettone]

I have visited Tony's page innumerable times but don't recall reading anything about the priming. It seems now he mentions it but doesn't go into details.

Anyway, thanks for the explanation!!
Kris

 

[Shortround6]

Sorry for the confusion, but as I understand it the electric primed ammunition was used for guns that needed to be sychronized and percusion primed ammo was used for guns that didn't need to be synchronized, through the prop guns and pehaps defensive weapons. The luftwaffe was concerned that ground crews might load the wrong ammo into the ammo bins if an aircraft used both types and render the gun/s with the wrong ammo useless for that flight.
To keep things simple they just segerageted the ammo by type of aircraft. 109 squadrons with through the prop guns got the non-sychro ammo (percusion) while the 190 squadrons with the wing root guns got the syncro ammo (electric). at least that is the story from Mr. Williams.

 

[Erich]

Getting back to page 1 about deletion of outboard 2cm weapons. yes and will speak from my cousins JG 301. the outboard 2cm was removed in the A-8 and many A-9's and the cannon opening in the wing was covered over. I have in the past posted photos of JG 301 A-9's with this very arrangement on the site, hopefully they have not been deleted. Again this was to the pilots discretion and was done by the "black men" in the field, this was not standard equipment shipment from the factory.

 

[Njaco]

Only gonna post this as the 'F' models were discussed a bit - from "Fw 190 At War" by Dr. Alfred Price.