Centerline weapons vs wing mounted weapons.

[Greyman]

Cowl guns are not mounted to the engine, so only one gun out of three is mounted on the engine. The engine is mounted on elastic mounts (rubber bushings) to cut down on vibration transmitted to the airframe.
...
The "light-as-possible aluminum mounting" may not be aluminium. It has to not only withstand the the recoil but hold the gun in place while the plane does a 6-7 "G" pull out or turn ( 22lb gun is now putting 132-154lbs of load on the mount) wing gun mount is usually attached to the spar/s. Some later mounts incorporated spring buffers to reduce the recoil load.

Technicalities aside, you know what I'm sayin'. A centreline weapon would be much more stable. For example, a .303 Browning in a Gladiator fuselage was measured to have a 100% group of 10 inches at 100 yards, while a single Browning in a Hurricane was measured to be about 36 inches at the same distance. Or a .50 Browning from a Grumman F4F making a group 46 inches in diameter! Or, the worst of the worst (albiet a bit off topic); the waist mount in a Fortress/Liberator made a group size 126 inches in diameter. Ouch.

Compare that to a benched .50 - a mere 3.2 inch diameter.

 

[GregP]

Hey Grayman, where'd you get the numbers? Just for reference, not questioning them.

 

[Greyman]

All over the place (so the comparisons/conclusions I'm drawing in my post may not be a solid bet - different measuring standards). Most of my data on guns and group sizes comes from PRO documents in London, but even then the same party isn't taking all of the measurements.

For example, some random Squadron Commander writes up the paper for the Gladiator group, an official Air Ministry Tactics memo publishes the Hurricane data, a Navy rigging diagram for F4Fs provides the .50 cal data, and an Army Ordnance manual has the benched .50 numbers.

 

[GregP]

OK, I can tell you from eprsonal experience that good groups are possible out to 1,000 yards.

 

[stona]

OK, I can tell you from eprsonal experience that good groups are possible out to 1,000 yards.

The problem in air to air combat is aiming a gun from a moving platform at another moving target. I've already made a post about the limitations of the gunsights used for most of WW2. The issues of various mounts simply compound the problem (as reflected in the larger groups for some) but are not in themselves the major problem.
A 1000 yard shot might be theoretically possible in a perfect scenario with zero deflection and I know that such claims were made.
For the vast majority of aerial combat this kind of thing is as,Shortround6 said,pie in the sky.

Walther Krupinski echoed an opinion expressed by almost every successful pilot on all sides.

"When you are brave enough to get in close,then even closer still,waiting until you pull the trigger,you will succeed."

Advice taken to heart by one of his star pupils Erich Hartmann.

As an aside Dowding saw a possible advantage in raking or enfillade fire from turret fighters engaging bomber formations in the chance for the "overs" to be effective on an aircraft other than the intended target. I'm a big fan of Sir Hugh but that's optimistic

Cheers
Steve

 

[vinnye]

I can see that there may be some advantages to centre line weapons - especially if the airdraft has a P38 / mossie type configuration - no problems with shooting through a prop etc.
But given that marksmanship was variable - not just due to skill but limitations of sighting systems and accuracy of or consistency of weapons used, a larger dispersal of guns may be advantageous?
This is why I would prefer - especially for a single engine type, wing mounted weapons - 6 or more 50 cals or 2 x 20mm cannons would do.

 

[Ascent]

A question.

If the aces stayed with their aircraft type throughout the war then how do they know that it was better then something they didn't fly in combat?

I get the impression that they stayed with it because they knew it's capabilities not because it was superior, which they wouldn't know anyway as they hadn't flown the other type.

 

[vinnye]

I suppose in the case of the LW, shortages of fuel to get air time with a different aircraft may make pilots reluctant to swop to a new aircraft.
If you had flown one type long enough to become familiar with its strengths and weaknesses - especially in combat, you amy want to stick with it so that when it matters - it does what you want / expexct it to?

 

[tomo pauk]

The single engined plane with 6 x .50s can be a mixed blessing, depending on installed engine power. The half of dozen .50 cals weights some 470-480 lbs, compared to two Shvaks that weight 180 lbs, or two MG 151/20 at 190 lbs, or two Hispano II at 220 lbs. The USN conclusion being one 20 mm cannon is worth 3 HMGs. The engine power of 1000-1100 HP at 15-20000 ft (=P-40, F4F-4) might be hard pressed to struggle with additional 250-300 lbs? The wing mounted guns also need gun heaters (=added weight), unlike the guns that are close to the engine. The weight that far from centerline should also hamper the roll rate.
The large dispersal mean also that you hit with one or two HMGs, instead of 6 you've brought into fray. Dealing far less damage than necessary to really harm the enemy airplane.

For the US and UK single engined fighters, the question is more or less an academic one: neither engine (radials, Merlin, V-1710) was enabling the gun to be fired through the prop, the Hispano was not been able to fire synchronized, the big drop in rate of fire for the synch BMG (along with need to go for 6 of them) meant that such way of installing them quickly lost favor. The high power of new US engines (two stage Merlin, R-2800) also canceled out the effects of the higher weight of the HMGs vs. cannons, along with non-availabilty of a cannon that would be as flexible as German or Soviet 20mm.

The two Hispanos in the wing were demanding the back-up, in form of another pair, or 4 LMGs, or 2 HMGs - in case of jam, the another cannon firing would throw the fighter out of aim much more if that happened to the Fw-190 or La-5/7.

 

[Shortround6]

We know the guns and ammo could do it (good groups) so it is a question of the mounts. The question is if the spread, or a good part of it, was deliberate or not. While the wing twisting a bit while pulling a hard maneuver is easy enough to believe the idea that wing that is capable of 400mph+ dives and pulling 6-7 G turns is going to flop around like a cooked noodle when firing on the ground at the butts seems a little much. At least under the impact of .30 weapon recoil. Since the British (at times) had a deliberate policy of miss aligning guns it doesn't sound out of line that they didn't put much effort into reducing group size (although it seems they upper limits on group size?) even if they didn't "design" a mount that allowed the gun to wobble a bit.

 

[Kryten]

The two Hispanos in the wing were demanding the back-up, in form of another pair, or 4 LMGs, or 2 HMGs - in case of jam, the another cannon firing would throw the fighter out of aim much more if that happened to the Fw-190 or La-5/7.[/QUOTE]

Actually the .303x4 or .50x2 was not there as backup in case of a jam, it was there to give the pilot options with what he engaged with, if you read through encounter reports considerable numbers of Spit pilots seem to fire the 20mm's alone then use the MG when ammunition ran out, the 4x.303 gave a far greater volume of fire and beaten area against soft targets when straffing, and I believe this is why they were often retained instead of the potentially more destructive 2x.50 setup!

 

[stona]

Actually the .303x4 or .50x2 was not there as backup in case of a jam, it was there to give the pilot options with what he engaged with, if you read through encounter reports considerable numbers of Spit pilots seem to fire the 20mm's alone then use the MG when ammunition ran out, the 4x.303 gave a far greater volume of fire and beaten area against soft targets when straffing, and I believe this is why they were often retained instead of the potentially more destructive 2x.50 setup!

You are muddling your time line. The installation of two cannon and four .303 MGs on the Spitfire in 1941 was seen,at the time,as a compromise due to ongoing reliability issues with the cannon. The first squadron to try a cannon only armament found it so unreliable that they swopped their aircraft for some clapped out machine gun armed Mk 1s from an OTU.

This evolved into the B type wing. The C type wing also usually mounted only two of the possible four,now much more reliable,cannon and four .303 machine guns. These versions were a compromise only in that the .303 machine guns were far from ideal as aircraft became more heavily armoured.

As soon as .50 calibre machine guns became available in numbers (from the US) the RAF dropped the .303s like a hot potato and the later combinations of cannon and .50 calibre MGs,as seen in the E wing, were not a compromise but seen as an effective armament package and you are correct about that.

Cheers

Steve

 

[Kryten]

I'm not personally convinced the position of the guns make a huge difference?
well lets think about the issue from a viewpoint that those of us who shoot can understand,
first off range, the ballistic drop meant the pilot must estimate the range accuratly,
dispersion, all guns suffer a degree of dispersion, some more than others even if ridgidly mounted,
wind drift, wind creates dispersion and drift and wind speed at altitude must have a bearing on the matter,
deflection , plane a or b are'nt stationary and being able to estimate range, speed and velocity of your rounds is critical
Slip, is your aircraft or your target slipping at all, is it maneuvering to evade?
finally concentration, are you fixated on your target or in a borderline panic looking over your shoulder every few seconds!

put it in context and no wonder the aces said get in close, no matter either few aircraft that knew they were under attack were hit!

I often hear it said the vast majority of victims had no idea they were under attack!

 

[GregP]

Hartmann and all the top aces flew all the aircraft. The top three (and more) simply decided they liked the Me 109's characteristuics better than the Fw 190. It probably had to do with familiarity rather than an absolute comparison. They liked the acceleration, rate of climb, and turning cahracteristics of the 109 better. If they had been ordered to fly the Fw 190, they would have done so, but they apparently had a choice. I've seen interviews with Hartmann years ago in which he said taht when the aces went to Berlin to receive decorations, they often flew the newest types of different aircraft and reported their observations to commanders or made their own choices if they were the commander.

In US service, almost nobody liked the P-47 at first, but they didn't have a choice. If the wing was re-equipped with them, they learned to fly and fight them as they gained experience in them. I'm sure there were units out there and people who preferred one type over another, but the commanders didn't have the leeway that top Luftwaffe commanders apparently did ... and the 109 was still in production. In 1945, if anyone wanted a P-40, it would have been from inventory, not from a new production line. When the war ended, the P-40 was no longer in front-line service, though it soldiered on until about 1958.

Later, many people loved the P-47, but you could hardly say it was "love at first sight."

 

[stona]

put it in context and no wonder the aces said get in close, no matter either few aircraft that knew they were under attack were hit!

I often hear it said the vast majority of victims had no idea they were under attack!

Exactly.
Also eliminate deflection as much as possible. Some pilots were very good at estimating this,most were lousy. Until sights that did the sums for you came in the advice of all those aces and experten was good advice. It is impossible to over state the importance of a good gun sight.
It is no accident that a significant percentage of aerial victories were scored by a minute percentage of the pilots flying. We still know most of their names today.
Cheers
Steve

 

[tyrodtom]

I think the choices the Germans aces were presented with were not that they could chose the aircraft their unit flew, but that they would be reassigned to a unit that flew the type of aircraft they wanted to fly.
When Hartmann flew the Me262, he could have flown it in combat, as commander of a unit that flew it in Germany only, but he didn't want to abandon his comrades on the eastern front.

 

[Kryten]

I did see a report on the increase in the number of successfull attacks once the gyro sight became available, but can't find it at the mo, I understand it made a considerable difference?

 

[GregP]

Gunsights are VERY inportant. I have looked through WWII gunsights, an F-86 gunsight, and a functioning MiG-15 gunsight in a MiG-15-UTI. The difference between a mid-WWII gunsight and, say, the MiG is astounding. And the MiG's unit is very easy to operate by comparison as well.

I'm not surprised at all that a new gunsight would make a huge difference in the effective employment of a particular type.

I have not looked through a working WWII German gunsight, but have looked through and operated a late-war gunsight from a Bearcat. Gyro sights made a huge difference. For the worst, look at the stalks mounted on the nose of a Bachem Natter!

 

[Greyman]

I did see a report on the increase in the number of successfull attacks once the gyro sight became available, but can't find it at the mo, I understand it made a considerable difference?

Recreation of 'Spitfire Combats: October 1944 to May 1945 - Comparison Between G.G.S. G.M.2 Results'

 

[CobberKane]

Maybe it would be worth sumarising the advantages/disadvantages of fuselage and wing mounted armament and seeing if everyone agrees:

Fuselage mounted - Advantages:
1. greatly reduces harmonisation issues (though this may remain an issue if differrent caliburs are used)
2. "Line of sight" aiming.
3. Concerntration of mass towards the centerline of the aricraft, aiding roll (more than ofset in twin engine designs by the weight of the engines!).

Disadvantages:

1. Reduced ammament carrying capacity (for single engine fighters)
2. Interuptor gear for cowl mounted weapons reduces rate of fire (ditto)
3. malfunction of or damage to interuptor gear can lead to prop being shot off (This was not hugely uncommon)

Wing mounted - Advantages

1. potential for more guns
2. reduced complexity

Disadvantages:
1. Decentralised mass
2. dispersed fire (except at point(s) of harmonisation

Did I miss anything?