Aircraft Spead and the interecept...

[Subchaser]

ORIGINAL: pasternakski

The Bf.109 "shoot through the prop" design was a leftover from obsolete WWI technology that had been abandoned by just about everyone else. The cam linkage necessary to make it work introduced just another maintenance headache and caused severe engine and prop bearing wear and damage when the guns were fired. Also, the difficulties and performance limitations presented by mounting a weapon inside the prop cowling extending back into the engine machinery were never completely overcome, either. Remember that this aircraft was "state of the art" for 1926, when its primary predecessor was introduced. By the time of the Battle of Britain, even the odd English Spitfire designs were superior - as fragile and flawed as those aircraft were.

Small wonder that the Fw.190 adopted the approach to weaponry configuration favored by Allied designers.

Pasternakski, looks like we have different opinions on this subject also. I don’t think that cowl and fuselage mounted synchronized weapons were ww1 leftover and definitly weren’t obsolete. Both variants had their own pluses and minuses.

Wing mounted armament provides better rate of fire and more room for guns to mount, but wings are the most vulnerable part of aircraft for g-forces, wing-mounted guns are more likely to jam because of g-force. You can’t choose the range on which your fire should concentrate, concentration point once set up on the ground, cannot be changed in the air, on all other ranges dispersion of fire is too great. Thunderbolts, Corsairs, Hellcats all were experiencing problems with hitting something at close range when target was flying at bit different angle. Ammo boxes in wings are more vulnerable to enemy fire than those in fuselage, thus they should have more serious armor, which increase weight.

Cowl mounted weapons usually had lower RoF, but this was compensated by larger caliber. Weapons in nose are not so easy to jam while heavy maneuvering. Most of the guns used in nose installations during ww2 were designed from the outset for synchronization, particularly the MG 17 and ShVAK, and with reliable synch-mechanisms were very successful. It was just 10% RoF reduction for MG-17 with synch. Fuselage mounted guns do have the advantage of concentrated fire at all ranges, so a fighter with fuselage-mounted guns needed fewer of them for the same general effectiveness.

Aircraft engineers of all nation were aware of advantages and flaws of both variants and usually their choice was dictated by design of a particular aircraft model, type of the engine, location of fuel tanks, overall construction durability etc. and sometimes because of fighter doctrine, preferences and current need of a customer.

You’ve mentioned early Spitfires, but where you think you can place those 6 mgs with sufficient amount of ammo. No such place under Spitfire’s cowling. Design of Spitfire aircraft corresponds limits to the design of Spitfire gun platform. With no reliable larger caliber available for RAF at that time the choice was obvious. The same goes to the most Allied aircraft, while almost all Bf-109 models (very successful shooter btw) and all Soviet fighter types had cowl-mounted weapons, Fw190D, Ta152, Do335, La5, La7, Yak9 and many other types had nose mounted weapons and were really good fireshooters, so you’re not right about ‘everyone else’.

[Brady]

pertsajakilu:

"Was that 20mm cannon same what was used in Japanese planes when war started? One of the pilots who didn't like Zero's cannon was Saburo Sakai who complained that Zero's 20mm was big, heavy and slow firing. And extra "goodie" was Zeros's "gunshight" which was primitive. These matters required a pilot with very good shooting skills. Sakai said about 20mm cannon. "it was like shooting dragonflies with rifle."

The A6M2, had the Type 99 MK I cannon in it, which was prety much a MG FF, this weapon packed a serious punch, howeaver it was dificult to aim, you neaded to be close to be able to effectively hit with it.

The A6M3, saw the introduction of the Type 99 MK II, This weapon fired the same prodjectile as the Type 99 MK I howeaver it had a larger case, containing more powder, The gun barel was also longer, and thus the weapon had a better range, and was easer to hit with.

The Type 99's were Navy guns, the Army used (amongst others) the Ho-5 20mm Cannon, this was a scaled vershion of the Browning 50 call, the Ho-103(12.7mm MG) was also a coppy of the Browning, though both were improved apon designes and not carbon coppys, and entirely different than the Type 99's, they had very high ROF's and good flat tradjectorys. Both were very effective guns, the Type 99's had more leatheal rounds, but the Ho's fired faster and were easer to aim, the Ho-5 is considered to be one of the Best 20mm Aircraft Cannons of the War.

I have personaly handeled all of these weapons, and I was extrealy impresed with the workmanship on the Type 99's they were beautifuly made, the Ho's were also very well made, I have some picks around somewhaer I might scan and post them...


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Wing mounting of weapons is generaly viewed as not Ideal, for various reasions, many of which subchaser has hit apon above, it should also be noted that only an 8 to 10 % reduction in rof is incured do to mounting the weapons to fire through the propeller, geting as many guns in the nose as posable is a good idea, they are easer to aim and are realy far more efficient than wing mounted guns for various reasions. Hub Mounted guns were used my The Russians, the Germans, and the US, in various fighters, Some of the Most suxcessfull fighters of the entire war, and indeaed in all of history used such weapons, the 109's the Yaks, and even the P39. It should also be noted that many of the weapons mounted to fire through the propelers of Aircraft typicaly had beter ROF than the US 50 cal browning, Particulary the Russian guns, wich would still of had a higher RoF even considerng the 10% reduction, than a 50 cal mounted on the wing.

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"Small wonder that the Fw.190 adopted the approach to weaponry configuration favored by Allied designers"

???, 190's had throught the war cowel guns and a pair of wing root 20 mm MG 151's, the Ta 152 even had the MK 108 in the engine, many 190's also had some out board 20mm or 30mm cannons as well, but these were mostly placed hear simply so more guns could be added for atacking Bombers.

[HMSWarspite]

Some sites you might find of interest (sorry if already referenced above)
http://www.csd.uwo.ca/~pettypi/elevon/g ... /fgun.html
http://www.quarry.nildram.co.uk/
http://homepage.tinet.ie/~frontacs/WBSt ... amage.html

[Brady]

Yes their (well two of them) are in part created by Flying Guns: World War II Author Tony Williams, his books are very well researched I highly recomend them to anyone interested in this subject mater.

[Brady]

p.

[mdiehl]

Yep, thats where Japan and Germany both were lacking

German aircraft were pretty good. The FW190 was competitive to the end, and the German 30mm was far superior to the Japanese designs. The .50cal was still king for shooting down fighters however, until the advent of really high thrust jet-engines allowed fighters to carry .30mm cannons with decent ballistic properties and sufficient quantitties of ammo.

For downing a US bomber the .50cal would have been adequate if you could get multiple hits. Assuming a range to target of, say, 300 yards, you're talking about 12,000 foot-pounds more or less. That's alot of energy transferred to a wing root, fuel tank, or engine mount. The advantage to a small cannon is in shrapnel effects on personnel. The disadvantage is that shrapnel from a 30mm isn't going to rip the wing off anything built in the US, nor is a non-detonating hit.

[Brady]

I see were learning nothing hear, thats ok though, for some the 50cal will always be the one true god.

[mdiehl]

You're not learning anything apparently, if you think a .50cal's effect is limited to penetration. But since you've sunk to straw men (that chickencr@p about the '1 true god') can the rest of us assume that you concede the point?

[Ron Saueracker]

I'm not getting involved! This is not a ladder rated debate.[:)]

[Mr.Frag]

Brady:

8x .50 cal = 8 rounds in the same general airspace

2x 20mm = 2 shells in the same general airspace

The 50 cal has a much higher rate of fire meaning over the same period of time much more rounds will be in the same general area.

The 20mm goes boom if it hits something but there are far fewer shells in the area to hit something.

Law of probability clearly favours the 50 cal.

Had Japan mounted 6x 7.7mm guns instead of 2x 7.7mm + 2x 20mm, they would have found more lead hitting the target.

A fire hose puts out fires a lot better then a garden hose. Why is that? Perhaps more water on the target?

It is the hit that kills you, not the miss. The more you fire, the better the odds on a hit.

Larger guns while being good at bringing down bombers really don't work in a fighter fighter. in a fighter fight, you want to spray as much lead into an area as possible and hope that some of it hits. The more you spray, the better the odds.

[Brady]

mdiehl, you will have to forive me, at times i grow weary of debating up hill aganst what would seam a leval of ethnocentricity that defiys lodgic, if in your case this is wrongly placed I apoligise, but from whear I am sitting it would seam so at present.

The US 50Cal, and the Ho-5 represented two entirely different aproaches to aircraft weapons systems, bit were effective in their own right, howeaver the US 50cal was largely far more inefecent a weapon compared to its contempoarys. The gun package on a US late war fighter typicaly of 6-50cal MG was as efective potentialy as the gun package of a Ki-84, and potentialy les lethal than that on a N1K2, this in referance to air to air engagements between the aposing sides. Most all aircomabt firing took place at 400 or less. The potential destrucive force of each Type 99 MK II round was almost equile to that of a Hispano round, as noted above:

""The US Navy concluded that a single 20mm Hispano was the equilvent to three .50 guns, the 20mm also had better Armor penatration and did not suffer so much from over heating" "

While the Ho-5 did not have quiet the destructive potential per round that the 20mm Type 99 did it made up for it with a blistering rof.

The typical argument aganst HEI weapons is that of penatraion vs balst efect, and it is always found wanting, both worked, and worked well, though the later produced far more efficent aircraft weapons systems.

[Damien Thorn]

The fact that almost all fighter planes today use the 20mm cannon pretty much settles the argument for me. And yes, I know that today's 20mm cannons have a significantly higher RoF and velocity than 60 years ago.

[Brady]

Mr. Frag:

"8x .50 cal = 8 rounds in the same general airspace

2x 20mm = 2 shells in the same general airspace"

The likely hood of getting hits with the 6 or 8 packs on US fighters is a bit better do to their abaility to spray and pray, though it is not as big as it would seam, US 50 cal guns could not sustain long burst's with out suffering from the chance of stopages or serious barel damage, this was true for most of the war, considering that moast all US fighters had only 6 guns in them, the seining advantgae you sugest hear is diminished a bit further, and even more so when you consider that the US 50 cal had a lower rof than prety much all the guns it faced.

"The 50 cal has a much higher rate of fire meaning over the same period of time much more rounds will be in the same general area. "

NO it did not in fact it was compared to it's contempoarys nothing special in this area.

"The 20mm goes boom if it hits something but there are far fewer shells in the area to hit something. "

Again not realy the case, I see we havent realy read much of what was posted above. Unless the 50cal goes in and hits somthing important not much is going to happen, the HEI rounds in 12.7mm and 20mm,ect that the Japanese used (heck even 7mm HEI was used) were intended to rip arart the airframe, they would have effect no mater whear they hit, and do to ther typicaly high ROF more than one would be landing in any given area.

"Law of probability clearly favours the 50 cal. "

Your math sources and premis are off hear.

"Had Japan mounted 6x 7.7mm guns instead of 2x 7.7mm + 2x 20mm, they would have found more lead hitting the target. "

The British found that large 30cal gun packages were inferiour to just a couple of 20mm guns and modified all their later war fighters to this standard, this is not a sound premis.

"A fire hose puts out fires a lot better then a garden hose. Why is that? Perhaps more water on the target? "

Again your not realy seeing this clearly.

"It is the hit that kills you, not the miss. The more you fire, the better the odds on a hit."

True the more lead in the air the more likely you are to acheave a hit, but if look above you will note that the US did not realy have a substantial advantage in this, and the effect of the hit in destructive force is another factor hear, each Type 99 round was a s effective as two or 3 50cal rounds.

"Larger guns while being good at bringing down bombers really don't work in a fighter fighter. in a fighter fight, you want to spray as much lead into an area as possible and hope that some of it hits. The more you spray, the better the odds. "

Again this is not quiet what you would paint it to be.

[Mr.Frag]

Brady, you are stuck comparing guns without noting the intended target type.

The 50 cal against Japanese aircraft was extremely effective. A 25 round burst of 6 to 8 guns literally filled the sky with lead. That is what you want to do against a fighter that you *may* be able to hold in your sights for 10-20 seconds.

The guns Japan had were shooting at a completely different type of target and needed completely different properties.

If you wanted to debate allied aircraft against allied aircraft or japanese aircraft against japanese aircraft, you might have some merits to your points but that is *not* what we are talking about.

We are talking about Allied aircraft shooting at Japanese aircraft which were effectively made of paper. In reality, the Americans could have gone to a lighter faster gun like a .303 and put even *more* guns on their planes and been even more effective.

[tiredoftryingnames]

So the answer here is to mount fire hoses on fighters and wash the enemy out of the sky.

[Mr.Frag]

The British found that large 30cal gun packages were inferiour to just a couple of 20mm guns and modified all their later war fighters to this standard, this is not a sound premis.

Different types of targets. Different results. Ask the germans about what they wanted ... more 30mm boomers because their targets were these damn bombers that just never went down no matter how many times you hit them.

[Mr.Frag]

So the answer here is to mount fire hoses on fighters and wash the enemy out of the sky.

Exactly, and the results are pretty clear ... Boom and Zoom with zip guns wins the day. It also requires far less pilot skill, something that is being ignored here.

[mdiehl]

Again not realy the case, I see we havent realy read much of what was posted above. Unless the 50cal goes in and hits somthing important not much is going to happen, the HEI rounds in 12.7mm and 20mm,ect that the Japanese used (heck even 7mm HEI was used) were intended to rip arart the airframe, they would have effect no mater whear they hit, and do to ther typicaly high ROF more than one would be landing in any given area.

The problem is that your claim, that the .50cal only has an effect if it hits something important (I prefer the word "dense"... the energy transfer and shock effects occur if you hit a wheel, a wing tank, a tire, a wing root, a spar, an engine or a pilot) also applies to the 20 and 30mm. The airframe just does not get very stressed out by a 20-30mm he burst because the air is so compressible and because the garden variety skin enclosing the air frame is a good "weak point" that allows the burst to escape. It's just not explosive enough to be lethal via compressive effects. If you were talking heavy caliber flak you'd have compression effects enough to stress the airframe, but 30mm just does not pack the explosive to do for an Allied fighter. It might do for a Japanese fighter, but to take down an Allied fighter (or bomber) you need multiple detonating hits and you still need to hit something important. If the shell does not detonate, with Japanese models anyhow you have a little hope of secondary effects via penetration but their penetration and kinetic energy effects are inferior to .50cal.

All I'm saying is that EITHER WAY. using a .50 or a 20-30mm, you don't do much damage unless you hit something (a) important and dense enough to detonate a shell or result in energy transfer from the .50, or, (b) really fragile so that the very weak explosive charge of the 20-30mm still results in stress to the airframe.

To my mind the choice in WW2 favors the .50 in fighter vs fighter combat because you have more ammunition and more guns firing.

For bombers the problem is different. The 20-30mm is desirable because the target is bigger, slower and more likely to be hit, and because you need to do a whole lot of damage as fast as you can. With the B-17s we see time after time that 20mm was scarcely better than .30cal. B-17s absorbed staggering amounts of damage. The US never put that sort of weapon in its fighters (with one notable exception) because the US never had to worry about having its cities bombed.

Now the only US fighter designed from the get go as a high-speed bomber killer (and subsequently emasculated by the removal of its supercharger when it went into production) was the P-39. It had a 37mm cannon because the US intended for it to destroy someone else's version of the B-17 should such a thing be encountered.

Getting back to fighter vs fighter, what's the problem here. The .50 had enough to easily do the job on any Axis fighter made at any time during the war, and it easily had the punch to easily destroy most Axis twin-engined bombers. Given that you get a couple more guns to shoot with and a little more ammo time, for me anyhow if you're not trying to down a B-17 the .50 is "where it's at."

[Mr.Frag]

Given that you get a couple more guns to shoot with and a little more ammo time, for me anyhow if you're not trying to down a B-17 the .50 is "where it's at."

Agreed and we never agree so it must be right! [:D]

[Brady]

"Different types of targets. Different results. Ask the germans about what they wanted ... more 30mm boomers because their targets were these damn bombers that just never went down no matter how many times you hit them. "

Arg, The British were fighting German Fighters and med. Bombers, just like the Japanese were (untill later in the war), they Both opted for (as did other countrys) a weapons package that was very similar two 12.7mm guns and two 20mm cannons, or similar load outs. A bunch of 7mm guns would of been fairly useless aganst the robaust American fighters.

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"30mm just does not pack the explosive to do for an Allied fighter"

One 30mm MK 108 hit was suficient to cut a spitfire in two.

US 50cal's were efective, they were just not ideal weapons, they were inefeiceent and consumpative, but they did work I am not arguing that.

The weapons on German and Japanese aircraft were also effective, and largely far more efective and efficient than the 50cal were over all, this is realy only true of certain Japanese plane types and gun packages, early 7mm types like the Oscar, and even the A6M2 while considerably better were not the best gun packages, these shortcommings were largely recitified later in the war howeaver.

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Some Quotes from Tony Williams excelent book, Flying Guns WW II, ISBN 1 84037 227 3:


p.149:

"Overall the USN and the USAAF stand out for their adhearance to the .50 cal, even when the airforces of all other nations adopted 20mm or even 30mm cannon as aramament, at least for fighter aircraft. This has led some to conclude that if the USAAF and the USN prefered the .50 browning, this must of been the best weapon available, better than the 20mm cannon. This view has resulted in claims of extreamly high preformance for this weapon, somtimes far beyond the reasionable. It was also common to underestimate the preformance of other nations weapons."

"At the end of the war some German and Japanese aircraft carried armor that was fairely effective aganst the 12.7mm projectiles. In some aircraft the USN and the USAAF did use the 20mm Hispano AN-M2, but although crews appricated the greater destructive power of the larger gun, they complained about it's reliabality."