Best Whirlwind armament layout to fight Japanese fighters and bombers?

[Admiral Beez]

In addition to the four 20mm cannons, the were several proposed armament layouts for the Westland Whirlwind.

1) Twelve 7.7mm Browning M1919 machine guns in the nose in groups of four in three rows
2) A single 37mm cannon
3) Four 20mm Hispano Mk.I's and four 7.7mm Browning machines

If going up against a large strike of Japanese bombers like the G4M and Ki-21, escorted by fighters like the Ki-43, Ki-44 or A6M which armament would you want for the Whirlwind? Total Japanese force is thirty bombers at 10,000 feet and twenty fighters at 12,000 feet .... opposed by two squadrons, or twenty-four radar-vectored Whirlwinds. We're presumably fighting over Burma/India or PNG/Aus sometime in 1942-1943.

My thinking is the fragile and incendiary Japanese aircraft seem ideal for the Whirlwind's four 20mm, but with sixty rounds per gun and no means to just fire one or two guns you'll quickly be out of ammunition. Did incendiary ammo exist for the first alternative's twelve banger? I assume the third alternative would have a separate switch for cannons and machine guns.

Were there other options considered for the Whirlwind? I don't think there's space in the wings to support conformal underwing gun pods. The bomb racks appear to be outside the propeller arcs so some sort of gun pod might work.

Something like this, Douglas DGP-1 twin .50 cal gun pods, though the drag will be nasty.

 

[wuzak]

By the time the Whirlwind could have been in action in SEA, belt fed Hispanos were available.

 

[Admiral Beez]

By the time the Whirlwind could have been in action in SEA, belt fed Hispanos were available.

Good point. What does that do to rof and ammunition load? I'm not including an aircraft redesign of belts under the pilot or such, so we're still limited by nose volume for magazine space.

In this engagement against matchstick opponents, would we be better off with just two belt fed Hispanos and the rest of the nose stuffed with ammo? The RAF's gunsights of 1942/43 should make for some precision shooting.

 

[ThomasP]

Somewhere on the internet . . . there is a scan of an original blueprint of the proposed improvements for the Whirlwind Mk II. Armament was to be 4x 20mm with 120 rpg (with the possibility of 2x .303 MG with 500 rpg also) in a modified nose. The redesigned nose also included a 25 Impgal (if the 2x .303 MG were fitted) or 32 Impgal (if only the 4x 20mm were fitted) fuel tank just in front of the rear bulkhead. There was also a 35 Impgal fuel tank added in the rear fuselage. Total fuel was intended to be 194-201 Impgal internal (vs 134 for the Mk I). DTs were also planned, though the size(s) were not mentioned.

There was also a proposal for 1x 40mm 'S' gun with 30-round servo-driven belt feed system, plus 2x .303 cal MG. I do not know whether this armament would have allowed the 25-32 Impgal fuel tank to be fitted.

 

[Shortround6]

The Whirlwind was trialed with all four guns in a row horizontally and using 115-120 round pneumatic powered magazines.
Like the upper left picture without the machine guns.

there was no 37mm gun. The gun in the photos of a single gun Whirlwind is a 20mm Hispano. What they were testing seems to be lost in time.
A number of books and many websites say the gun is a 37mm but the British had no 37mm gun in development at any of the British gun companies or government arsenals.
37mm was not a standard British gun size and no other British gun in several decades was a 37mm. (except for purchased guns). British had a variety of 40mm guns (2pdrs).

 

[Admiral Beez]

Alrighty, I'd say we've got the different armament options laid out. So now, what so we want on our twenty-four Whirlwinds for taking on the fifty incoming Japanese?

 

[A.G. Williams]

there was no 37mm gun. The gun in the photos of a single gun Whirlwind is a 20mm Hispano. What they were testing seems to be lost in time.
A number of books and many websites say the gun is a 37mm but the British had no 37mm gun in development at any of the British gun companies or government arsenals.
37mm was not a standard British gun size and no other British gun in several decades was a 37mm. (except for purchased guns). British had a variety of 40mm guns (2pdrs).

The single mounting shown is certainly a magazine-fed Hispano (the muzzle brake visible in the pic has a distinctive shape and was only used with magazine-fed versions of the gun).

There were a few dozen WW1-era 37 mm COW guns still around in WW2 and there were suggestions for fitting them to aircraft for anti-invasion purposes, but the surviving ammo was old and dubious, so they used the guns for airfield defence instead (ironically, they later made some more ammo for them). They would have needed a better form of ammo supply anyway, as the 5-round clips weren't good enough.

 

[tomo pauk]

My pick - 3 belt-fed Hispanos with as much of ammo carried as possible.

 

[Admiral Beez]

The single mounting shown is certainly a magazine-fed Hispano (the muzzle brake visible in the pic has a distinctive shape and was only used with magazine-fed versions of the gun).
.

For taking on this Japanese strike this single Hispano version might be useful, especially against the bombers. I assume the extra space in the nose was dedicated to larger ammunition capacity. The single Hispano would be firing 700 rpm or 12 rounds per second down target. Only a few hits into the unprotected bombers and lightly built fighters should do the trick.

 

[Admiral Beez]

My pick - 3 belt-fed Hispanos with as much of ammo carried as possible.

A three gun armament would be unusual. I don't think that was a proposed armament option, but the 4 belt-fed Hispanos does seem to be on the table.

 

[tomo pauk]

I don't think that was a proposed armament option.

I'm proposing it.

 

[Admiral Beez]

I'm proposing it.

Then you're in the wrong thread.

We're discussing the best of the armament options tried by Westland and the Air Ministry to deal with a strike of fifty Japanese aircraft. As much as I'd like to have seen underwing mg pods like in my opening post, it does not appear to have been considered, and is not an option. If anything is on the table for our Whirlwind we'll be listing off additional random brain farts like RP-3 rockets, 40mm Vickers S guns, M1 launchers (bazookas), etc. I suggest we stick to the task at hand.

 

[Shortround6]

four 20mm guns, with or without the extra three .303 guns would seem to be the best option if we are allowed a little leeway.

If strictly as trialed (test fired/mocked up) then the twelve .303 nose would offer the best compromise between firepower, firing time and reliability.

The "continuous feed" system referred to in the picture caption was the pneumatic powered system and not belt feed. Consumption of compressed air was way, way beyond what was anticipated and the planned (and fitted) air bottle would only fire a few rounds from ONE gun before the air supply was gone and the fitted compressor could not keep up. Four guns using the compressed air magazines would have needed a substantial air supply and compressors.

So while there was room for belts with 120rpg and four guns were fitted with 120round magazines I am not sure if four guns with belts ever made it to the mock up stage.

 

[Admiral Beez]

four 20mm guns, with or without the extra three .303 guns would seem to be the best option if we are allowed a little leeway.

It was mocked up, so I'd say it passes the bar as a legitimate weapons option. I like this option too, as I assume the pilot has two gun switching, so can use his cannons to down the bombers and the .303 machine guns (especially if incendiary rounds are available) against the lightly built fighters.

 

[ThomasP]

I suspect the single off-center weapon set-up was just for fit/firing trials for the port inboard 20mm gun. The original intent was to have the outboard 20mm guns in the rear position, as in the top picture below.

The blister in the upper right corner of single 20mm gun picture was clearance for the top outboard corner of the port 20mm ammo boxes, after they moved the inboard guns to the rear position and the outboard guns to the forward position. Shown in the pictures below.

Also, the 40mm 'S' gun was going to be mounted on centerline, so . . .?

 

[Peter Gunn]

Always liked the Whirlwind, except the somewhat goofy looking tail, but that's not a deal breaker.

I like option 3:
3) Four 20mm Hispano Mk.I's and four 7.7mm Browning machines

My question then is ammo capacity, can you get more firing time for the 20mm Hispanos by removing the four 7.7mm Brownings? I realize we're going up against E/A less robust than western counterparts, but I'd still like as much hitting power as I can get for as long as i can get it.

 

[Admiral Beez]

I suspect the single off-center weapon set-up was just for fit/firing trials for the port inboard 20mm gun. The original intent was to have the outboard 20mm guns in the rear position, as in the top picture below.
View attachment 603815

The blister in the upper right corner of single 20mm gun picture was clearance for the top outboard corner of the port 20mm ammo boxes, after they moved the inboard guns to the rear position and the outboard guns to the forward position. Shown in the pictures below.
View attachment 603816
View attachment 603818
View attachment 603819

Also, the 40mm 'S' gun was going to be mounted on centerline, so . . .?

Great pics. Is there any other British twin engine WW2 era aircraft that tried so many nose gun options? The Mosquito comes to mind of course.

 

[SaparotRob]

I would go with whichever option would spit the the most tracers for the longest time. This is my 20-20 hindsight talking. This Whirlwind isn't going after Lancasters or Fortresses.
I believe tracer rounds have plenty of phosphorus to ignite gas fumes or fuel leaks.

 

[A.G. Williams]

The "continuous feed" system referred to in the picture caption was the pneumatic powered system and not belt feed. Consumption of compressed air was way, way beyond what was anticipated and the planned (and fitted) air bottle would only fire a few rounds from ONE gun before the air supply was gone and the fitted compressor could not keep up. Four guns using the compressed air magazines would have needed a substantial air supply and compressors.

Thanks. Do you have any references or further details about that? I don't recall Wallace's Guns of the RAF mentioning this, and he was responsible for Hispano developments for much of the time.

 

[Shortround6]

I may have had a senior moment.

In any case Pages 41 and 43 of Niall Cordaroy's book " Whirlwind" has an account of the Hydran or "M-Type" feed. The feed was a box of vertical cells holding un belted rounds with a worm drive underneath with a pneumatic stepper motor, which fed the rounds. Prototype feeds were made of 121 rounds for the Whirlwind and inner guns of the TYphoon, 114 rounds for the outer guns of the TYphoon and a 300 round unit for the Beaufighter.
The Much published photo of the single gun Whirlwind may be aircraft L6844 which had a redesigned nose and a single 20mm gun with the Hydran feed for testing. The feed did not work under conditions of negative G and stoppages were present even in very short bursts. even after modification.
By August 1940 the plane had been fitted with four guns and magazines for further trials, which revealed two more problems, the 2nd of which was that the magazine consumed air pressure so quickly that after a single long burst the pressure dropped below what was needed to function. The Whirlwind carried no air pump so the only source of air pressure was the bottle in the nose. No air firing of all four guns was carried out.

I have put it into may own words but the source is as above. One or more other publications (soft bound one by 4+ publications) may have accounts of the feeds and problems.