"No sleeve-valve engines" scenarios

I don't know if any of you recall the "Dyna-Cam" of 200 HP. The owner used to bring it to the San Diego EAA fly-in during the mid-80's.
What Happened to the Dynacam (Revolver-Cam) Engine?

Just did a quick measurement on a Merlin cutaway.

A H-Merlin would be approximately 48-49 inches across, if horizontally opposed, assuming standard stroke and rod length.

Kevin J said:

Without the Sabre or Centaurus, you'd be looking at the Vulture, R-2600 or R-2800. So imagine this, a fighter that you could operate anywhere in the World in WW2, a worthy successor to the Hurricane, a competitor to the Spitfire.

Click to expand...

Mustang?

gjs238 said:

Mustang?

Click to expand...

That was my immediate thought too. The Brits already have a war-winning in-line poppet-valve engine. RAF Mustangs all round please.



Give the Brits P-51D fighters. No Sabre or Centaurus needed and you've got "a fighter that you could operate anywhere in the World in WW2"

I think pretty much everyone has agreed that the net effect would be roughly nil.

swampyankee said:

I think pretty much everyone has agreed that the net effect would be roughly nil.

Click to expand...

That means no Typhoons from 1942 to 1944 to counter the low level Fw 190a fighter bomber raids. No Tempests to knock down the V1. Of course we might have had a Double Mercury to power the Typhoon/Tempest and a Double Pegasus to power the Warwick, but when would these engines have become available?

Kevin J said:

That means no Typhoons from 1942 to 1944 to counter the low level Fw 190a fighter bomber raids. No Tempests to knock down the V1. Of course we might have had a Double Mercury to power the Typhoon/Tempest and a Double Pegasus to power the Warwick, but when would these engines have become available?

Click to expand...

Why would it take longer to develop and produce poppet-valve equivalents to the Sabre, Mercury, and Centaurus than the sleeve-valve engines? Remember, production sleeve-valve engines were unique to the UK.

A great deal of hype has been expended on sleeve valves. See http://www.enginehistory.org/members/articles/Sleeve.pdf to be somewhat disabused of the general superiority of the sleeve.

Given an equal expenditure of effort, Napier* could probably have gotten a liquid-cooled, H-24, 2000+ hp engine into reliable service months earlier than the Sabre. At least a half-dozen manufacturers were producing high-output, air-cooled, poppet-valve radial engines; only Bristol was building sleeve valve engines. Bristol had abandoned development of poppet-valve engines; had they not done so, there is no technical reason they could not have produced poppet-valve engines of the same or greater power density than their sleeve-valve radials.

----------
* Of course, at this time, Napier was having problems producing any kind of reliable engines. Their production (all poppet valves) before the Sabre were excessively complex and not known for their spectacular reliability. It's likely Napier would have significant trouble getting a serviceable 2000+ hp engine into service regardless of the type of valves.

swampyankee said:

* Of course, at this time, Napier was having problems producing any kind of reliable engines. Their production (all poppet valves) before the Sabre were excessively complex and not known for their spectacular reliability. It's likely Napier would have significant trouble getting a serviceable 2000+ hp engine into service regardless of the type of valves.

Click to expand...

Much of the problem Napiers had was its factory which was modern in 1890 and had gone downhill since. One of the problems with the sleeve valves was they were machined in one building loaded onto an iron wheeled handcart then taken across a cobbled yard to the heat treating building then rattled back across the cobble yard to the assembly building. Napiers could hand fit and assemble a good engine but it never had any sort of proper production line till it was taken over by English Electric who built a new shadow factory in Liverpool to build the Sabre.

Napiers main product since 1918 had been the Lion W12 engine a hand asembled file to fit engine with hardly any interchangeable parts, which was one of the reasons the RAF refused to buy any Napier Lion engined aircraft after 1930 and got rid of the ones they had by iirc 1933. Basically the only engines Napiers London factory built during the war apart from the early few Sabres was a few hundred Sea Lion engines for RAF rescue launches which the RAF stopped using for new launches as soon as better engines were available from the USA.

Kevin J said:

That means no Typhoons from 1942 to 1944 to counter the low level Fw 190a fighter bomber raids. No Tempests to knock down the V1

Click to expand...

In neither case did the war hinge on the results. Increased British casualties yes but either form of German attack was not accurate enough to cause much damage to the actual war fighting ability of the British.
Had the British not built the Typhoon they might have built a few hundred more Spitfire XIIs. Reassigned some of the Mustang Army co-operation squadrons to low level interceptor?

The Tempest did do a lot of good work shooting down V-1 but it was not the only plane to do so.

Tempest squadrons that shot down V-1s number a total of 7.
They claim about 805 (depending on source or shared claims)
Two squadrons shot down 528 between them.
3rd highest claiming squadron was flying Spitfire XIVs as was the 5th highest scoring squadron with 108.5 kills.
4th highest scoring squadron was flying Mosquito XIIIs

The next Tempest squadron (501)( I don't know where it stands on the overall list) claimed from 72-95 V-1s.

33 squadrons claimed at least one V-1 kill.

Had the 7 squadrons flying Tempests been flying something else perhaps more V-1s would have gotten through. But it was hardly a case of Tempests providing the only defence of England against the V-1 and so the Tempest was essential.

Kevin J said:

That means no Typhoons from 1942 to 1944 to counter the low level Fw 190a fighter bomber raids. No Tempests to knock down the V1.

Click to expand...

If I read the OP's premise correctly, sleeve valves never reached production. This does not mean that Bristol sits on its collective bum and swans along with the Jupiter; they could have easily devoted the same effort to developing poppet valve engines as did, say, Curtiss-Wright, Pratt & Whitney, BMW, etc, and Napier could have developed yet another H engine with poppet valves, as they had done before, and had such unsuccessful engine makers as Rolls-Royce, Jumo, and Daimler Benz.

By the time the Napier was producing 2,400 hp in service, Merlins were producing 1,700 hp. A poppet-valve equivalent of the Sabre could have easily reached the same power as that achieved in service by the Sabre.

swampyankee said:

If I read the OP's premise correctly, sleeve valves never reached production. This does not mean that Bristol sits on its collective bum and swans along with the Jupiter; they could have easily devoted the same effort to developing poppet valve engines as did, say, Curtiss-Wright, Pratt & Whitney, BMW, etc, and Napier could have developed yet another H engine with poppet valves, as they had done before, and had such unsuccessful engine makers as Rolls-Royce, Jumo, and Daimler Benz.

By the time the Napier was producing 2,400 hp in service, Merlins were producing 1,700 hp. A poppet-valve equivalent of the Sabre could have easily reached the same power as that achieved in service by the Sabre.

Click to expand...

Both the Mercury and Pegasus were poppet valve. The Packard Merlin in 1945 produced IIRC 2218hp with water injection in the P-51H; the RR Merlin in the 1944 DH Hornet produced 2030hp. So the wartime Merlin ended up producing the same amount of power as the wartime Sabre.