Best Allied bomber destroyer.

[mhuxt]

According to many sources (eg Price) it took an average of 20 x 20mm shells to take down a US bomber. Where 1 or 2 x 30mm could do it.

When they worked out the average pilot's accuracy, most would take their full ammo load to knock one out, more likely just damage it.
Hence the heavy twins usefulness and gondolas under wings with big guns for the singles (at the price of lowered performance).

The Germans actually reckoned on 5x30mms being required to take down a Viermot with certainty, though you're right about them having reckoned on 20x20mm as well.

The table at the end of this pdf rates various weapons combinations for the late war Luftwaffe. Their aim was to get a high rate of fire of destructive shells with a low-weight weapons combination - they reckoned on 5% hits from aimed fire. Top of the class was a weapons mount of two 30mm MG 213/30 (not sure if it ever saw service, not my area of knowledge), which the boffins rated as 1.0, which was then compared to the combination of weight and required firing time, based on 5% hits, rate of fire and ammo and ammo used of other weapons setups (six MG 151/15s, four 20mm cannon, two 30mm cannon and one 50 mm cannon).

Their numbers showed the BK 50mm as next to useless. View attachment ammunitions.pdf

 

[Rufus123]

No you'd use your Spits against the bombers' escorts and something else, with heavy armament, for the bombers. If there were no escorts then the Spits could go for the stragglers.
A Spit/Mossie/Tempest combination (2 stage engined ones) if you were just using British equipment.

Instead of as a bomber destroyer think of the Spit as a escort destroyer. Can't have one without the other. The best bomber destroyer is going to have a hard time without something to clear off the escorts.

Tempest with under wing guns perhaps or rockets perhaps, the thing is so fast that it would still have enough speed.
Heck you can even add rockets to a Spit, they did after the war, possibly even underwing guns if you have enough to clear the escorts and have some left over for pure bomber work.

Heck, if there were no escorts (or they were kept away) a Mossie with the 57mm Molins guns would do some damage.... plus rockets. Shouldn't be too hard to put a couple of 30mm in the front of a Mossie too.

This is what I was thinking on part of this. Two plane types at a minimum and maybe more then two plane types with at least one type dedicated to keeping the escorts occupied. Maybe a dual purpose craft and one dedicated to bomber destruction.

 

[Shortround6]

Germans need to follow that route because they didn't have the engines needed for a single engine bomber interceptor.

The Allies don't.

Four 20mm Hispano guns are a decent anti-bomber armament. Not the greatest but well above most single engine fighters. Roughly equal to a FW 190 with two 13mm and four 20mm Mg 151s ( not all 20mm cannon are equal).

Better than 109 'gun-boats'

Allies have Napair Sabre, P W R-2800 and R-R Griffon engines in quantity that allow the carrying of 4 20mm guns in a single engine fighter with enough performance to engage both escorts and bombers. Maybe Tempests aren't the best for anti-escort work at 25,000ft but they would be a heck of a lot better than most twins. Or to put it another way, they may not be able to defeat the escorts and get to bombers at times but they DON'T need to escorted by other fighters.

The Germans did not have many over 2000hp engines or engines that offered 1500hp and up at 25,000ft. This made it much harder to build large all purpose fighters.

 

[Gixxerman]

A Mossie with 4 x 20mm cannon 4 x .303 always looked like a lethal bomber killing combo to me.
Given the way things turned out the need just never really arose in the same way it did for Germany I suppose.

 

[muscogeemike]

The P-61 does not have any more firepower than a Tigercat and is much slower. Perhaps the P-61 carries more ammo.

Possibly true but the P-61 did engage in the war - the Tigercat didn't.

 

[stona]

A lack of ammunition in relatively small fighters is also a problem when they are equipped with numerous or large calibre weapons. What the allies would have done had the need arisen must surely be reflected in what the Germans actually did when confronted with the same problem.

The Luftwaffe developed a weapons pod to fit in the bomb bay of the Me 410 with 2xMG 151/20s (giving a total of four 20mm cannon and two MG 17s). This pod could also carry 230 rounds per cannon. It was a stop gap due to delays in MK 103 production. They really wanted the larger calibre.

II./ZG 26 got aircraft equipped with the 5cm BK (fitted by Auto-Union Chemnitz for anyone who drives an Audi!) but it proved practically to be less effective than the MK 103, which would be supported by the figures posted in the link above.

Trials were carried out with various 3.7cm Flak guns (18 and 43) in ever more desperate efforts to fit something that would destroy the bombers.

Galland insisted several times at various meetings that the MK 103 30mm cannon was what was really needed.

I agree with Galland (it's not often I can say that) and the Luftwaffe. The allies are going to need to fit larger calibre weapons to their bomber destroyers and they are going to have to protect those bomber killers with something like the Spitfire XIV.

Cheers

Steve

 

[JtD]

Well, the original question was more along the lines of

Or to put the question in a more pertinent way if the Germans had of been able to put one type of Allied fighter into production for the sole purpose of shooting down B24's and B17's then which one would have been the best choice?

than along the lines what the Allies needed to develop in order to counter a bombing threat. I would say that once the Germans had the 262, they pretty much had the best aircraft for that task available. So I'd say the question is about if there's anything Allied that would have been better than the 109's and 190's or even the 110's they had been using before the 262 came along.

 

[swampyankee]

Possibly true but the P-61 did engage in the war - the Tigercat didn't.

And the P-61 got air-air kills, usually at night. It also had a reputation for very good maneuverability (not just for its size, but on an absolute scale). Put the "C" engines into the "E" airframe, and it may manage 440-450mph at altitude.

 

[stona]

Well, the original question was more along the lines of than along the lines what the Allies needed to develop in order to counter a bombing threat. I would say that once the Germans had the 262, they pretty much had the best aircraft for that task available. So I'd say the question is about if there's anything Allied that would have been better than the 109's and 190's or even the 110's they had been using before the 262 came along.

Yes, but the allies didn't really have a bomber destroyer of the type needed to meet these hypothetical enemy four engine bombers. They didn't have one because they didn't need one.
My point is that since they didn't have anything to do the job properly they would have to develop one. It would need to be based on something already in existence to be achieved in a reasonable time frame.

I'd use the D H Mosquito, but I don't know much about the potential of the P-61.

Cheers

Steve

 

[Shortround6]

Let me see if I have this right.

AN Me 410 with four MG 151 20mm guns ( and 230rpg) and two 7.9mm MGs is a bomber destroyer?

A Mosquito with four 20mm Hispano guns with 150rpg and four .303s ( with 500rpg) is a bomber destroyer?

A Corsair with 20mm Hispano guns with 231 rpg is not?

Those rifle caliber machine guns must make all the difference.

I wonder what kind of plane you need to "escort" the Corsairs?

BTW, just stick four 20mm Hispano guns in a P-47?

3-4 Hispano guns in P-38? You could swap four .50s with 500rpg for two 20mm with 150rpg and SAVE 438lbs. or add the 4th 20mm gun (196lbs for the P-38 installation) and another 150 rounds (92lbs) and have 150lbs to spare (more than enough to bring all four 20mm guns to 200rpg)

 

[pinsog]

Let me see if I have this right.

AN Me 410 with four MG 151 20mm guns ( and 230rpg) and two 7.9mm MGs is a bomber destroyer?

A Mosquito with four 20mm Hispano guns with 150rpg and four .303s ( with 500rpg) is a bomber destroyer?

A Corsair with 20mm Hispano guns with 231 rpg is not?

Those rifle caliber machine guns must make all the difference.

I wonder what kind of plane you need to "escort" the Corsairs?

BTW, just stick four 20mm Hispano guns in a P-47?

3-4 Hispano guns in P-38? You could swap four .50s with 500rpg for two 20mm with 150rpg and SAVE 438lbs. or add the 4th 20mm gun (196lbs for the P-38 installation) and another 150 rounds (92lbs) and have 150lbs to spare (more than enough to bring all four 20mm guns to 200rpg)

Agree 100% with everything you said here. P38, P47 and Corsair. All 3 of them have the horsepower to carry a heavy cannon armament without affecting performance AND all 3 can tangle with the best fighters in the world on more or less equal footing. The P47 above 25,000 feet would be a nightmare to defend against. The P38 in later models, especially the unproduced P38K variant would be another major thorn in a bombers side. I think we are very lucky these 2 fighters were on our side and not the Germans.

Shortround,
Whats your best guess for ammo capacity if you installed 4 Hispano 20mm's in a P47?

 

[stona]

The Luftwaffe didn't consider four or even six (with another proposed gun pack) 20mm cannon enough to guarantee knocking the bombers down. I'm not suggesting that it couldn't be done, many bombers were shot down by 20mm cannon, but they wanted something bigger for their bomber killers.
They may have estimated five 30mm cannon shells to down a four engine bomber, and this was the weapon that some, notably Galland, were pushing very hard for. Others really wanted something that would offer a one hit solution.
I usually defer to the opinion of the men who were actually fighting the battle as to what weapons might work best.

As I've said before in many different threads, relating to many different aircraft, just "sticking" four 20mm cannon in a P-47 may be much easier to write than do.

Cheers

Steve

 

[Shortround6]

Weight wise it could be around 400rpg But P-47s seldom carried the full 425rpg possible for their .50 cal guns. Underwing loads usually meant a restricted ammo load, there may be some question as to the ability of the 20mm gun and feeder unit to move a 400 round belt without help. But 240 20mm rounds or so per gun for 4 guns would correspond to 267-276 rounds per gun for eight .50 cal guns with under wing loads.

I don't know if there is a spacing problem with spars.

 

[Shortround6]

Four 20mm Hispano may not be ideal but it is better than the gunboat 109s and is arguably as good or better than a 190 with four MG 151/20s.

Without inventing a new gun the 20mm Hispano is as good as it is going to get. The 37mm M4 cannon has a miserable rate of fire, 1/4 that of a "normal" Hispano gun, each shell is very powerful but the hit chance is very low. The velocity and time of flight also require getting closer than the 20mm Hispano. The gun also weighs about double what Hispano does. The Vickers S gun is even bigger and slower firing (about 2/3 the 37mm or 1/6 the rate of fire of the 20mm Hispano). It also has velocity and time of flight problems which argue against long range gunfire.
Please note that these rates of fire are for the standard British MK II or American M-2 guns. The British introduced the short barreled MK V gun with a higher rate of fire before the war ended and the Americans were working an a faster firing Hispano and adapted it after the end of the war. Rates of fire went up 20-25%. The British Molins company had built prototype guns firing at up to 1000rpm during the war.

 

[JtD]

Yes, but the allies didn't really have a bomber destroyer of the type needed to meet these hypothetical enemy four engine bombers. They didn't have one because they didn't need one.
My point is that since they didn't have anything to do the job properly they would have to develop one. It would need to be based on something already in existence to be achieved in a reasonable time frame.

Well, neither had the Germans when the 8th AF started operating. Or are you saying that the gondola equipped 109 was a better bomber destroyer than any aircraft the Allies were fielding at the time?

 

[stona]

Well, neither had the Germans when the 8th AF started operating. Or are you saying that the gondola equipped 109 was a better bomber destroyer than any aircraft the Allies were fielding at the time?

Not really. The addition of gun pods, rockets, mortars and the experimentation with ever larger calibre weapons on Luftwaffe fighters simply reflected a realisation that the standard armament was not sufficient for bomber killing operations.
That standard armament on Luftwaffe single engine fighters was not particularly lighter than most allied types. That's why I am arguing that the allies, had the tables been turned, would have had to up gun one or more of their fighters to make a good bomber killer.
Cheers
Steve

 

[pinsog]

As I've said before in many different threads, relating to many different aircraft, just "sticking" four 20mm cannon in a P-47 may be much easier to write than do.

Cheers

Steve

If a dainty little Spitfire (that will probably draw some return fire), a Hurricane, Typhoon, Tempest, FW190, early P51, F4U, F8F, and even some Japanese planes could mount up 4 20mm, then what on earth could keep them out of a P47?

 

[drgondog]

nothing

 

[Glider]

I'd use the D H Mosquito, but I don't know much about the potential of the P-61.

Cheers

Steve

So would I with the 6pd Mollins gun if there are no fighter escorts, one hit would probably do it in most cases and few would escape two hits

 

[CobberKane]

Regarding the use of 40 and 50mm cannon and the like, what were the pro's and cons of these? The LW trialled everything up to 75mm. My understanding is that the idea was to sit back out of range of the defensive fire of the bombers and keep lobbing shells until one hit, one being probably enough. Of course, flying slowly behind the bomber stream would be tantamount to suicide with escort fighters around. In those circumstances the LW seemed to prefer the high-speed-pass-and-outa-there approach, for which I guess a smaller faster firing weapon might be better. Does the use of heavy (40mm plus) cannon assume a fighter free environment?