Best Whirlwind armament layout to fight Japanese fighters and bombers?

[PAT303]

Twelve .303's each loaded with 500 rounds of AP and Incendiary would destroy any Japanese aircraft with a 2-3 second burst, and be 100% reliable while they do it.

 

[A.G. Williams]

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.

Thanks for the clarification. I have read about the Hydran feed and seen photos of it, but it is rarely mentioned.

 

[Admiral Beez]

Twelve .303's each loaded with 500 rounds of AP and Incendiary would destroy any Japanese aircraft with a 2-3 second burst, and be 100% reliable while they do it.

It's a good point on reliability.

 

[ThomasP]

For tomo pauk

The idea was that the guns could use either 60-round drums or belt-feed. Unfortunately I do not have any info on the number of rounds-per-gun for the belt-feed.

Also it might be interesting to note that, during the continued development stage, the different weapon fits were intended to be installed in quick change noses modules. ooooohhhhh!

 

[Admiral Beez]

For tomo pauk

View attachment 603924

The idea was that the guns could use either 60-round drums or belt-feed. Unfortunately I do not have any info on the number of rounds-per-gun for the belt-feed.

Also it might be interesting to note that, during the continued development stage, the different weapon fits were intended to be installed in quick change noses modules. ooooohhhhh!

It might be faster to swap out the nose rather than waiting to reload four (or more?) magazines.

These chaps have to pull off the nose cone and swap out the magazine drums. Put some quick release anchors and swap out the nose?

As an aside, I have to like this shark look.

 

[PAT303]

For tomo pauk

View attachment 603924

The idea was that the guns could use either 60-round drums or belt-feed. Unfortunately I do not have any info on the number of rounds-per-gun for the belt-feed.

Also it might be interesting to note that, during the continued development stage, the different weapon fits were intended to be installed in quick change noses modules. ooooohhhhh!

A very effective armament if it worked but it didn't, unreliable ammunition, unreliable guns and even if it did work as designed you only get 9 seconds of firing time, just enough ammunition to walk the rounds onto the target before running out. 12 reliable .303's with 20 seconds of firing time shooting proven AP, Tracer and incendiary ammunition is the best bet.

 

[Admiral Beez]

A very effective armament if it worked but it didn't, unreliable ammunition, unreliable guns and even if it did work as designed you only get 9 seconds of firing time, just enough ammunition to walk the rounds onto the target before running out. 12 reliable .303's with 20 seconds of firing time shooting proven AP, Tracer and incendiary ammunition is the best bet.

How many .303 hits would be needed to take out a Betty or Sally bomber?




How does the Whirlwind match up against the Oscar, Tojo or Zero at 10-12,000 feet?

 

[PAT303]

How many .303 hits would be needed to take out a Betty or Sally bomber?




How does the Whirlwind match up against the Oscar, Tojo or Zero at 10-12,000 feet?

12 concentrated .303's firing at 1150rpm per gun will put approx 460 rounds out every 2 seconds, a burst from 6 o'clock lengthways up through the fuselage is not going to do the crew any good, likewise a mix of 460 AP and incendiary rounds into an engine is going to be 100% fatal. Pilot reports from Burma talked about 12 gunned Hurricanes shredding Japanese aircraft quite convincingly.

 

[Admiral Beez]

What chances does a Whirlwind have against Oscar or Zero? The British fighter is faster than either, but rate of climb and agility will be detriments.

 

[tomo pauk]

It might also climb better. One Peregrine was making almost the power of an early Sakae (and more with altitude decrease if 100 oct fuel is used by Whirly), and Whilry has two engines vs. one with Japanese.

 

[Admiral Beez]

It might also climb better. One Peregrine was making almost the power of an early Sakae (and more with altitude decrease if 100 oct fuel is used by Whirly), and Whilry has two engines vs. one with Japanese.

With a gross weight of 10,356 lbs, compared to the Ki-43's 5,710 lbs, the Whirlwind will need all the power it can get.

AIUI unless the engine is replaced with a higher compression version, the extra octane makes no difference. There are no new Peregrines to be made into high compression engines, so what does 100 or even higher Octane do to help?

 

[tomo pauk]

With a gross weight of 10,356 lbs, compared to the Ki-43's 5,710 lbs, the Whirlwind will need all the power it can get.

AIUI unless the engine is replaced with a higher compression version, the extra octane makes no difference. There are no new Peregrines to be made into high compression engines, so what does 100 or even higher Octane do to help?

Anyone that suggests the higher compression on any piston engines at RR will be promptly fired by by Hives.
100 octane gives another 100-150 HP between Sl and ~11000 ft on the Peregrine, tapering out from there to 15000 ft to zero extra HP.

 

[Admiral Beez]

100 octane gives another 100-150 HP

In the absence of greater compression. Why?

But good, our Whirlwinds need all the power they can get.

 

[wuzak]

In the absence of greater compression. Why?

But good, our Whirlwinds need all the power they can get.

More boost.

 

[tomo pauk]

In the absence of greater compression. Why?

But good, our Whirlwinds need all the power they can get.

Bingo - more power is usually always good.

Id also suggest a few small changes to the engine installation; nothing major. See whether it would be easy to have ram air intake copied from the Gloster's fighter, the convoluted air intake on Whirlwind will rob any ram effect that is beneficial to the altitude power. The less restricted and un-masked exhausts (again from Glosters'?) for better exhaust thrust. Not sure whether it would've been easy to install better carburetors?
All of this, with a bit of luck, should've netted another 10-15 mph at altitude, and improve practical ceiling.

 

[A.G. Williams]

More boost.

Exactly. As I understand it, higher-octane fuel has little effect by itself, its value is that it permits higher boost pressures to be used.

I recall reading that the Merlin engine went through its entire development process using the same valve timing and compression ratio: all of the increases in power (which doubled from 1939 to 1945) were due to the boost pressure being turned up as higher-octane fuel became available.

 

[Admiral Beez]

Exactly. As I understand it, higher-octane fuel has little effect by itself, its value is that it permits higher boost pressures to be used.

I recall reading that the Merlin engine went through its entire development process using the same valve timing and compression ratio: all of the increases in power (which doubled from 1939 to 1945) were due to the boost pressure being turned up as higher-octane fuel became available.

Thanks, I've been wondering how the octane alone made a difference. My turbocharged car requires 91 octane, and AIUI if I put in 95 or even 100 octane fuel it makes no difference in power with the stock setup, beyond paying more for marketing gimmicks at the gas station. But, if I could adjust the boost level like our Whirlwind pilot can, the higher octane makes more power. Now I understand, I think.

 

[Shortround6]

There are a number of factors which affect the detonation limit. (point at which fuel in the cylinder will either start to combust without spark plugs (ping) or "flash" and burn all at once (detonate) rather than burn as a moving flame front across the cylinder from the point of ignition.
Most these have to do with the temperature of the fuel/air mixture in the cylinder as the piston approaches top dead center.
The more boost (above the ambient air pressure) that is used the higher the temperature of the mixture, the reason that both inter coolers and water injection were used.
the higher the cylinder compression the higher the temperature in the cylinder as the piston reaches the top of it's stroke due the heat of compression in the cylinder.

The ability to use more boost (cram more fuel/air into the cylinder) beats the power advantage (more power for the amount of fuel burned) of higher cylinder compression.

Please note this is for peak or max power, the engine with higher cylinder compression will give better fuel economy in cruise.

This is just for making power and has nothing to do with the engine parts being strong enough not to break under the increased loads or the engine cooling system to keep up with increased amount of fuel being burned.

 

[Admiral Beez]

Conversely, would the Ki-43 or A6M have trouble shooting down the Whirlwind? Beyond a speed advantage, the British fighter has an armoured cockpit, bullet resistant windshield, self sealing fuel tanks and two engines. As for survival of a damaged Whirlwind, in addition to engine redundancy and integral fire extinguisher systems, there's no fuel forward or behind the cockpit to burn the pilot.

 

[A.G. Williams]

This is just for making power and has nothing to do with the engine parts being strong enough not to break under the increased loads or the engine cooling system to keep up with increased amount of fuel being burned.

Good point. For the R-R engineers, developing more power was easy once the right fuel was available. Keeping the Merlin functioning reliably when experiencing much greater stresses than it was designed for was another matter.

As I recall, it was said of the R-R engineers that they were nothing special in terms of engine design, but were absolutely terrific at engine development.