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View Full Version : Why did England and U.S. planes rarely have cowl guns?



telven
01-24-2004, 11:31 AM
With the exception of the B-239, P-36, P-40B, P-39 I'm curious on why those countries never put any centerline guns in their planes? I think every other country except them had some sort of weapon that was centerlined.

Was it the way their engines were designed?Is it more aerodynamic? I would much rather have a Spit IX with 2x20mm and 2x.50 cal in the nose rather than in the wings. Or a P-51D with 2x.50 cal in the nose and 4x.50 in the wings.

telven
01-24-2004, 11:31 AM
With the exception of the B-239, P-36, P-40B, P-39 I'm curious on why those countries never put any centerline guns in their planes? I think every other country except them had some sort of weapon that was centerlined.

Was it the way their engines were designed?Is it more aerodynamic? I would much rather have a Spit IX with 2x20mm and 2x.50 cal in the nose rather than in the wings. Or a P-51D with 2x.50 cal in the nose and 4x.50 in the wings.

MystiqBlackCat
01-24-2004, 11:38 AM
I think it may have had something to do with having to sync the guns with the propeller and that lowered British and American weapon's rate of fire fairly significantly. plus having weapons in the cowling can possibly limit pilot's visibilty such as the bulges on the Me 109G6 and later FW190 when they recieved MG131s. To eliminate that the nose had to be redesigned to better incorporate the new armament.

Could just be a designer preference.

blabla0001
01-24-2004, 11:39 AM
My guess is that they didn't like to fire through the prop.
By placing the guns in the wings they can use their full rate of fire and you don't have to install a mechanism to prevent your guns from shredding your prop into toothpicks.

Chuck_Older
01-24-2004, 11:43 AM
Look at two classic examles, the Bf 109 and the P-51

The Bf 109 had an inverted engine- take a look at the exhaust stacks. So there was some room up there on top of the decking for MGs.

Now consider the P-51. The engine is installed in the typical manner, cylinder heads up. So the Vee of the engine is taking up a lot of space to the sides of the engine.

There's other reasons too but this I think is a major one. On radial engined US fighters, i suppose the thinking was that there were so many guns, and since there were no cannon, stick 'em all in the wing and leave room for turbocharger ducting, etc., on the cowl.

But you're forgetting the P-38, of course. Well, there's exceptions to every rule http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

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1.JaVA_Razer
01-24-2004, 11:50 AM
Yhea but P-38 didn't have a nose proppeler/engine.

But I think that(as many people said) the US and others prefered the More is better instead of less is more tactic. Ok your pilots needed to be a fairly good judge of distance and convergence but so what. You could do MORE damage in less time+ I have a feeling ammo stores where bigger this way thus enabeling to do more damage.

blabla0001
01-24-2004, 11:50 AM
"But you're forgetting the P-38, of course. Well, there's exceptions to every rule"

My guess is because it's a twin engine so no prop in front of the guns.

Chuck_Older
01-24-2004, 11:54 AM
Well, of course, lol

That's why it's an exception. But the placement of the engines dictated that nose installation. Same idea as what we're talking about but in reverse- engine placement dictated gun placement.

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SkyChimp
01-24-2004, 12:02 PM
Many US fighters up to WWII did have cowl guns: P-35, P-36, P-40, P-43. Even the F4F Wildcat initially had cowl guns. The F4U Corsair was initially desinged with cowl guns as well. Of course, the P-39 had cowl guns.

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horseback
01-24-2004, 12:21 PM
In addition to the factors mentioned above, there is a Center of Gravity issue to deal with as well. The weight of the guns, added to the ammo, added to the weight of the synchronization gear, plus the modification of the aircraft's profile (and therefore, drag)all had to be factored into the design. More weight in the nose usually means a longer fuselage aft of the CG to balance, which might call for a larger tailplane, which... you see my point.

British and US designers (generally) chose a set of compromises that maximized both performance and firepower (and firing time) for the average pilot, who wasn't likely to need the long range accuracy provided by nose mounted armament.

Cheers

horseback

"Here's your new Mustangs, boys. You can learn to fly'em on the way to the target. Cheers!" -LTCOL Don Blakeslee, 4th FG CO, February 27th, 1944

Korolov
01-24-2004, 01:11 PM
Don't forget the A-36 had cowl guns, except they were on the underside of the cowl.

http://www.mechmodels.com/images/newsig1.jpg

LeadSpitter_
01-24-2004, 01:25 PM
mantainance and rearming was alot quicker with wing mounted mgs. To rearm nose mounted weapons you had to take apart the whole nose basically, p38s had that problem and took very long to rearm and refuel 45m+

spitfires and hurricanes can be rearmed and refueled in less then 20min becuase of the wing mounted mg and cannon.

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NegativeGee
01-24-2004, 01:46 PM
With regard to the FW-190, it was not initially conceived with cowl mounted guns. They were added after the engine was changed from the BMW 139 to the BMW 801. The engine change created sufficent space to allow the installation of guns over the cowl. All of the original designs weapons (2x MG 17, 2x MG 131) were located in the wing roots.

The Bf 109 had cowl mounted guns because that was all that was asked for in the original design requirement, and the inverted Jumo engine made this a logical choice of location (plus Messerschmitt liked thin wings on his designs).

"As weaponry, both were good, but in far different ways from each other. In a nutshell, I describe it this way: if the FW 190 was a sabre, the 109 was a florett, or foil, like that used in the precision art of fencing." - Gunther Rall

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Arms1
01-24-2004, 03:45 PM
i'm not sure about us a/c, but in gb when the oringinal order for an 8 gun fighter that was capable of intercepting high speed bombers was put forth the engine to be used (merlin) was still in its early design stages.

Copperhead310th
01-24-2004, 04:37 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Korolov:
Don't forget the A-36 had cowl guns, except they were on the underside of the cowl.

http://www.mechmodels.com/images/newsig1.jpg <HR></BLOCKQUOTE>

lol Beat me too it.

actually it had 6 .50's. 2 in each wing & 2 "Chin" Mounted undr the nose. Very intesting.
Meshsmother has already compleated the A-36 Appachee for FB. No cockpit. though. I wonder if we'll ever see that model in FB?
the **** pit should be very simaler to the P-51B.

http://imageshack.us/files/380th%20siggy.jpg

BerkshireHunt
01-24-2004, 05:14 PM
Why did England and U.S. planes rarely have cowl guns?

According to Morgan and Shacklady's book on the Spitfire, in 1935 the British Air Staff conducted a series of tests to determine the best way of destroying an enemy fighter aircraft (which was assumed to be powered by a 700 hp engine and to be constructed from stressed aluminium). These showed that on most occasions a pilot would have only two seconds to fire at a target. So rate of fire was judged the most important factor in an aircraft's armament. A number of machine guns and cannon were investigated, including the Colt Browning .303, the .50, the 20mm Oerlikon FF (later manufactured under license in Germany as the MGFF), the 20mm Hispano and various others by Vickers, Madsen and COW.
The highest rate of fire (and reliability) was given by the .303s so they were chosen for installation in all new British prototype fighters (commissioned from Supermarine, Hawker, Bristol and Gloster).
The design specifications issued all stipulate that "the machine guns must be placed outside the propellor arc". It was thought that whilst interrupter gears might be acceptable on a two- bladed prop (in 1935) they would become increasingly difficult to produce, and more deleterious in their effect on rate of fire, as propellor 'solidity' increased (ie number or width of blades). And this was sure to happen as engine power increased.
Hawker was given permission to study the installation of fuselage guns on the Hurricane (in 35/36) but the company asked to be allowed to concentrate on an 8 gun wing armament. It thought combining interrupter gear with a variable pitch mechanism too much to incorporate in a prototype- given that Britain was trying to re-arm in a hurry. And in any case the 'rate of fire' argument was unassailable at the time.
The later concept of 'weight of fire' (ie a slow- firing cannon having the same or greater destructive effect as several small machine guns), was not really taken into consideration- numbers of bullets were the thing so far as the Air Staff were concerned.
The manufacturers had other ideas, however, and as early as 1934, RJ Mitchell at Supermarine had designed wing- mounted cannon installations for prototype fighter designs- but it seems no cannon was then sufficiently reliable to be actually used. Licence production of the 20mm Oerlikon FF was rejected by Supermarine because it was slow- firing and unreliable (the Germans improved its reliability and installed it outside the propellor arc of the 109E) and the British Air Ministry instead took a licence for the French 20mm Hispano cannon. Ironically, this long- barrel gun had been designed for fuselage installation on the Dewoitine D520, and others, but the British thought they could increase its 2 second destructive effect by installing it in the wings of their fighters (ie by not reducing its rate of fire with an interrupter gear).
That is why the Hispano wing installations (on Spitfires, Hurricanes and Typhoons) all look as though an outsize gun has been stuck in a small wing (the only exceptions being later Tempests which used re-designed Hispanos with shorter barrels).
There is obvious merit to the argument that you are better off having cannon mounted outside the propellor arc, even in the later war years, but it ignores the explosive effect of individual shells which also plays a major role in weapon effectiveness. Fears about the difficulty of producing interrupter gears we now know were unfounded- though quite how you would synchronise a gun to fire through a five bladed prop on a griffon Spit is anyone's guess. There must come a point where you are interrupting more than firing?
The only people who seem to have got this right were the Russians. Historian Bill Gunston wrote recently (in Aeroplane magazine) that their aircraft gun technology during WW2 was superb- certainly better than Britain and America's (both of which fought the war with weapons designed in the 1930s) and better in some respects than Germany's. Russia's guns shot at such a high rate of fire there was little practical penalty in synchronising them with a prop so fuselage installations were de rigeur.
I can find no reference anywhere to Rolls Royce being asked to design a hollow propellor shaft for the Merlin as Daimler Benz and Junkers Jumo did. I can only assume this was thought too disruptive to production as it would have meant a major re-design- and in any case the British were fixated on wing armanent for single engine fighters (though they had nose cannon in the Whirlwind, Mosquito and Beaufighter).
I don't know why American single engine designs veered away from fuselage guns but I'd hazard a guess that they were influenced by British voices- it's easy to forget the degree to which operational experience was passed on to America before the USA entered the war.

[This message was edited by BerkshireHunt on Sat January 24 2004 at 04:52 PM.]

EPP-Gibbs
01-24-2004, 06:57 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by NegativeGee:

The Bf 109 had cowl mounted guns because that was all that was asked for in the original design requirement, and the inverted Jumo engine made this a logical choice of location (plus Messerschmitt liked thin wings on his designs).

<HR></BLOCKQUOTE>

The First versions of the P51 had fuselage mounted Mg's too. Mounted in the lower front position.

Re the Me109 early models like the B,C, and D featured wing and cowl mounted Mg's The E model introduced the MGFF cannon into the wings. From the F model onwards wing armament was deleted in favour of cowl/through Spinner mounting. One of the reasons for this was that Messerschmitt struggled with wing armament because of the design of the wing. It was a relatively weak wing structure and gave problems with wing armament. It's thin-ness per se wasn't the issue, after all, Supermarine were able to fit 8x .303, or two Hispanos plus 4x.303 (or 2 x .50) into the Spitfire wing which was even thinner than that of the 109.

It was more to do with strength, and the Spitfire wing was very strong whereas that of the 109 wasn't so. The undercarriage of the 109 was mounted onto the fuselage. This did facilitate wing changing, but the main reason was the wing wasn't strong enough to support the weight of the aircraft. The penalty was tricky ground handling, take-off's, and landings, owing to the very narrow track.

The FW190 reverses the trend completely by offering a strong wing capable of heavy wing armament, plus carrying a very wide track undercarriage, thus eradicating the ground handling and armament shortcomings of the 109 resulting from its weak wings.

If I had all the money I'd spent on drink..I'd spend it on drink!

Korolov
01-24-2004, 07:04 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by LeadSpitter_:
mantainance and rearming was alot quicker with wing mounted mgs. To rearm nose mounted weapons you had to take apart the whole nose basically, p38s had that problem and took very long to rearm and refuel 45m+
<HR></BLOCKQUOTE>

No, the reason the P-38's cowl was hard to get open was because it was a very tight fit. All of those guns are put into a small place, that will make it hard to access them.

Wing mounted guns werent piled in a block-ish battery of four in the wings like the P-38s.

http://www.mechmodels.com/images/newsig1.jpg

p1ngu666
01-24-2004, 07:49 PM
hope we get the a36 http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

Arms1
01-24-2004, 08:40 PM
excellent post BirkshireHunt, ty

Aaron_GT
01-25-2004, 03:59 AM
With regard to the Hurricane, Hawker
built a 4 cannon version in 1937 for tests,
even as the Hurricane was entering
service trials.

In late 1937 the RAF
issued a specification calling for a
fighter with 50% more effective armament
than the 8 gun fighters just entering service.
(This gave birth to the Tornado - Typhoon - Tempest - Fury series). Hawker had actually
been working on this design from mid 1937,
with a 12 gun armament. I don't know if the
RAF essentially issued the spec to match
his initial designs, though.

DaBallz
01-25-2004, 09:55 AM
One other concideration not mentioned here
is that guns shooting through the propeller
arc sometimes thoot the prop.
Even properly synched guns will misstime after
over heating after a long burst. The ammunition
fires from heat after being chambered.

A gun mounted between the cylinder banks firing
through the gear box/spinner adds another
problem, excessive length and as a result loss
of visibility, especially on the ground.

Of course Radial engined planes can not fire through the gear box and suffer an areodynamic
peanalty of a larger frontal area.

Wing mounted guns have no advantages except
an allowable increase in firepower and ease
of accessability.

The outboard weight and resulting loss of agility
along with increase in wing thickness are the
chief problems.

Wing mounted guns won in the west. Almost all
fighter planes had cowl mounted guns at one time.
The P-36, P-39, P-40, P-43, P-51, all started
with cowl guns. The P-47 never did, nor did most
naval fighters. Only the P-39 design never dropped
the cowl guns, the P-43 became the P-47.

Da

MB_Avro
01-25-2004, 03:03 PM
Excellent topic and responses...!!

During the Battle of Britain,it has been suggested that the wing mounted armament an the Hurricanes and Spitfires allowed for a wider 'spread' of fire and benefitted the less experienced pilots of the RAF.

In other words,they were more likely to make at least some hits on the target rather than none at all.

Regards
MB_Avro

Abbuzze
01-25-2004, 03:50 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by EPP-Gibbs:

It was more to do with strength, and the Spitfire wing was very strong whereas that of the 109 wasn't so. The undercarriage of the 109 was mounted onto the fuselage. This did facilitate wing changing, but the main reason was the wing wasn't strong enough to support the weight of the aircraft. The penalty was tricky ground handling, take-off's, and landings, owing to the very narrow track.
<HR></BLOCKQUOTE>

You mixed it up a bit, you are right that the 109 gear was centerd to make the change of wings easier, but let us take a look about strengh... every single-engine fighter in WWII could pull a lot of g´s, so the wing of the 109 could hold 6 or even 8 g... compare it to the 1 g when a plane is standing at the ground and.. http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif
It´s more a question of construktion, wingguns increase the weight which is not located in the centerline- an this reduce the performance (remember the FW190- later version had only cannons in the wingroot).

Hmm, I forgot, the 109 was sharing a lot of groundhandling troubles with the Spitfire... the VVS refused them cause of the weak gear (for russian airfields!). http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif

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horseback
01-25-2004, 07:50 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Abbuzze:
Hmm, I forgot, the 109 was sharing a lot of groundhandling troubles with the Spitfire... the VVS refused them cause of the weak gear (for russian airfields!). http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif

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<HR></BLOCKQUOTE>
It might be pointed out that the USAAF was offered the opportunity to have the Spit Mks VIII/IX license - built here in the States, but it was passed up because the ones given to the US for evaluation didn't stand up too well to the distances and normal use expected of US military aircraft. Studies showed that we could pack more fuel tanks into it to get the range needed for escort purposes (like the MK VII high-alt fighter, or the recon types), but that the aircraft wouldn't hold up structurally to that kind of extended use. They thought 'beefing it up' would cost the aircraft the very qualities that initially made it desireable, so, except for a few 'reverse Lend-Lease' cases, like the 4th, 31st, and 52nd FGs, there were no American Spits.

Just as well, I expect. It's bad enough that Ford built Liberators, and GM built Wildcats and Avengers, but it would be hard to stomach saying "Chrysler, or (God forbid) Studebaker Spitfire," don't you think?

Cheers

horseback

"Here's your new Mustangs, boys. You can learn to fly'em on the way to the target. Cheers!" -LTCOL Don Blakeslee, 4th FG CO, February 27th, 1944

Kampfmeister
01-25-2004, 07:57 PM
One more thing. I once heard that German pilots preferred to have their guns mounted on the centerline, especially those that flew 109's, because guns mounted in the wings tended to jam or not fire properly when pulling High G's during a dogfight. Something to do with the center of gravity on the plane I think. I'm not an engineer, but has anyone else ever heard of this, and can you elaborate with a better explanation?

DaBallz
01-26-2004, 03:44 AM
Studebaker built Wright R-3350's and P&W R-2800's.
GM built more Wildcats and Avengers than Grumman, way more.
And the GM built Wildcats (FM2) were better performers
than the Grumman version.

I agree with the statement about the structural
"weakness" of the Spit. it was a great plane
as is, but add a few tons (US Tons) of fuel
and it would have been too weak for combat.

Remember, a plane stressed for 8 G's will be
good for 4 G's at double the weight.

The reason foor the inboard landing gear on the
Bf-109 and Spit (as I remember) was to attach
the gear to the heavy structure of the fuselage
instead of the additional weight required to be
added to the wing to support outboard attach points.

Da...