Wi: Fairey Fulmar

IIRC Ricardo's rational for sleeve valves was based on the problems with heat transfer and detonation with poppet valves as engines got larger and the charge and compression figures got higher. Sleeve valves were seen as the means of increasing valve area and thereby improving the 'Breathing' of the engine, allowing greater airflow and exhaust flow so increasing the charge capacity of the cylinder.
 
Indeed. However, the 4 valves per cylinder tech was known well before sleeve valves were introduced. Bristol was ahead the world with this, too, since they introduced 4-valve heads on their air-cooled radials (eg. Mercury, Pegasus).
The 'breating', once superchargers were introduced on mayor scale, made engines with even 2 or 3 valves per cylinder very much workable.
 
I believe that four valves per cylinder on a two row radial presented real problems with how to actuate the valves on the rearward bank of cylinders.
 
One might use short camshafts for each pair of either intake or exhaust valves per cylinder.

added: A picture of a model of the Mercury. Both intake and exhaust valves were driven via pushrods installed in the front of cylinders. Thus, make another set of pushrods for the back cylinders behind the rear row of cylinders.
 
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Anderman

Donor
I believe that four valves per cylinder on a two row radial presented real problems with how to actuate the valves on the rearward bank of cylinders.

One might use short camshafts for each pair of either intake or exhaust valves per cylinder.

added: A picture of a model of the Mercury. Both intake and exhaust valves were driven via pushrods installed in the front of cylinders. Thus, make another set of pushrods for the back cylinders behind the rear row of cylinders.

The large double rows only use two valves per cylinder

Wright R-2600
https://en.wikipedia.org/wiki/Wright_R-2600_Twin_Cyclone

Pratt & Whitney R-2800
https://en.wikipedia.org/wiki/Pratt_&_Whitney_R-2800_Double_Wasp

BMW
https://en.wikipedia.org/wiki/BMW_802

Nakajima Homare
https://en.wikipedia.org/wiki/Nakajima_Homare

 
The large double rows only use two valves per cylinder

The 1-row engines from those companies also used only two rows per cylinder.
But then, it just shows how the layout of valve gear takes a back set to many other things, like cubic capacity, ability to run at good/high RPM range, ability to sustain boost, capacity of supercharger etc.
 

Anderman

Donor
The 1-row engines from those companies also used only two rows per cylinder.
But then, it just shows how the layout of valve gear takes a back set to many other things, like cubic capacity, ability to run at good/high RPM range, ability to sustain boost, capacity of supercharger etc.

With cubic capacity i think you mean displacement? That is easy to solve for Bristol just twin the Perseus and you get a 18 cylinder with 49,8 L 3040 cubic inch.
 
With cubic capacity i think you mean displacement? That is easy to solve for Bristol just twin the Perseus and you get a 18 cylinder with 49,8 L 3040 cubic inch.

Yes, displacement.
Looking a bit at Perseus, it have had same bore and stroke as the Hercules. So perhaps Bristol skips Aquila and Taurus and goes diectly on Hercues and 'almost Centaurus' (= Perseus-derivative with 18 cylinders). The later should be giving 1800+ HP already on 87 oct fuel.

On the other hand, perhaps an interesting development would've been air-cooled V12s. For the UK, such an engine that uses Pegasus cylinders as base gives and engine with 2340 cu in (39.7L), or 1300 HP with 87 oct fuel. Granted, that is not a major power, but has much lower drag than usual radial engine, while being lighter than a liquid cooled V12, and without a vulnerabilty of the cooling system. Can use off-the-shelf parts (no new technology needed), say, Bristol and De Havilland enter a joint venture to make it.
 
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With cubic capacity i think you mean displacement? That is easy to solve for Bristol just twin the Perseus and you get a 18 cylinder with 49,8 L 3040 cubic inch.

Isnt that basically the Centaurus. I think if someone had managed in the mid 30s to persuade Bristol they didnt need to build 5 engines in the 600 to 1000hp range and get them to concentrate on just 2 engine types and a decent supercharger. A larger Perseus 30 litres or so should give about 1,200hp. The Hercules using 14 of the larger Perseus cylinders should get to 2,000hp and both engines without the choking 90 degree bends in the intake manifolds should be better at altitude.

Basically Bristol needed someone like Ernest Hives to rationalise things.
 

Anderman

Donor
The Hercules cylinders have the same displacement as the Perseus. Hercules is basically a 14 cylinder Perseus. For some reason Bristol simply didn´t just twinned the Perseus 2 cylinders were dropped per row. And Bristol were not the only company who did that Wright, Nakajima and Mitsubishi did the same iirc.
 
Hercules-engined Spitfire makes plenty of sense IMO. Sorta mid/late ww2 Japanese A/C, or as close the Fw-190As as possible. By late 1944, Hercules was making almost 2000 HP, also gaining, finally, a proper exhaust system; post war more than 2100 HP was available by versions that were in production and service. Talk Bearcat level of performance.

Re. the picture - I'd remove the under-wing radiators (that also removes a significant source of drag, to cancel-out increased 'nose drag') ;)

It would help to spread the landing gear apart. Might have to redesign the main wing spar.
 
People at Bristols and/or AM were probably of the opinion in early 1930s that 18 cyl engine, that will weight more than 2000 lbs dry even in the 1st iteration is a step too far? For me, with Perseus in production (= the tooling for sleeves and other tiny bits is already purchased), skip the Aquila and Taurus all together, go straight to the 14 cyl 'big' engine (pre-Hercules) by 1935, and 18 cyl derivative by 1938.
Thus there is an almost-Centaurus in low volume productionn by 1939-40, and in mass production in 1941. Graft the initial engines on the alt-Fulmar, and later versions on Typhoon, Tempest, Barracuda and Firefly. Make a twin multi-pupose A/C with 2 x 2000 HP radials, or/and 'Victory bomber' with 4. The 'pre-Hercules' can be used from day one on Halifax (seems it was a better bomber with Hercules aboard), Wellington and Whitley (no Tiger version), perhaps also on alt-Beaufort, since there is no Taurus around.
Earlier series/mass production of the 'Hercules' might also bring about a 2-stage supercharged version, Bristol snatched several altitude records with 2-stage supercharged Pegasus between the wars.
 
I believe the issue with early Centaurus (and the US equivalents) was overheating, in that they had an unfortunate tendency to melt.
Without computers, it takes a fair bit of trial and error to sort this out. So the Hercules was an interim solution that could be cooled properly.
 
I believe the issue with early Centaurus (and the US equivalents) was overheating, in that they had an unfortunate tendency to melt.
Without computers, it takes a fair bit of trial and error to sort this out. So the Hercules was an interim solution that could be cooled properly.

The Wright R-3350 was certainly a troublesome machine (a feat shared with early BMW 801Cs and Ds), while R-2800 went from decent to a very reliable engine.
IIRC the only problem with early Centaurus was that there was not enough of production capability, with Bristol producing Mercury, Pegasus, Perseus, Taurus and Hercules by late 1930s. Those smaller Bristol's engines were urgently needed (or perceived as such), Centaurus was not. The examples installed on Tornado were working with less troubles than the Sabre-engined Hawkers, however Napier's other engines were not that necessary for the needs of RAF/FAA. Hence Napier was left with a choice of perfecting the Sabre into a reliable engine, or bust. They managed both :)
 
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