Alfa Romeo 136 R.C.25 - Aircraft of World War II

Burmese Bandit · 05-25-2009, 05:42 AM

While researching engines which might have been used by the Axis to design a better fighter and/or bomber in WWII my attention was caught by this Italian engine, which, according to the Wiki (not that I trust it 100%, but it's much more often right than wrong!) says -

"...At the time of its first running in 1938 and 1939 it was the most powerful radial engine in the world, generating just less than 1492 kW (2000 hp) on 100-octane fuel."

Although the 135 in question is then described as having "...Power output:1177 kW (1600 hp) at Take Off, 1030 kW (1400 CV) at 3200m..." Wiki goes on to say that a variant, the Alfa Romeo 136 R.C.25, had a power output of

"...Power output:1765 kW (2400 hp) at 0m, 1360 kW (1850 CV) at 2500m..."

TWO THOUSAND FOUR HUNDRED HORSEPOWER AT SEA LEVEL????

If that was true, and it was produced in the very early years of the war, why wasn't it used as the primary engine for thw Wurger - especially the ground attack version???

Did this engine have reliability problems, or production problems, or was it just a case of German Technical Jealousy???

I have searched this forum and the net, but i have not been able to come up with the answers to those questions.

Which is why I am asking the very knowledgeable members of these forums - could someone enlighten me on the history and fate of this (on paper at least) world-beating engine of its time?

red admiral · 05-25-2009, 04:42 PM

I'm not sure when the 136 itself was produced but the 135 is from around 1938/39.

There were a few initial problems with the 135, mostly relating to the cam ring breaking, but reliability was otherwise good. The Germans did some harsh reliability tests against the BMW 801 and found the 135 to be much better. Its a little bit wider than the 801 but shorter and lighter.

Burmese Bandit · 05-25-2009, 07:25 PM

AHA! Thanks, Red Admiral...

So then, it is as I suspect...the old GERMAN JEALOUSY monster rears its head again...

Who can tell me more? I am intending to resurrect my old 'could you have desiged a better warbird' thread around this engine, and I would like more input before I do so.

b0ned0me · 06-02-2009, 08:04 AM

I can't add much more than you have already found, but I have myself been intrigued by that engine - if for no other reason than it seems to be based on a licence-built Bristol Pegasus 'doubled', which indicates what Fedden might have been able to achieve if he hadn't bought into Ricardo quite so whole-heartedley.

I have to say I'm a bit suspicious of that 2400hp number. Not to disrespect the Italians, but could Alfa Romeo really volume-produce an engine early-war that would match a late-war R-3350? Only 150 of these engines were made, and my feeling is that getting an 18-cylinder four-valve radial to 2400hp for testing might have been doable, but achieving the same on a mass-produced engine with standard-issue fuel would be another matter. If that were the case, then the 2400 hp from the 136rc25 would be like the 2200hp from the early Napier Sabre - available from the test bed and the workshop, but not from the factory.

[edited to correct stupid typo]

Burmese Bandit · 06-02-2009, 08:42 AM

Good point, and by the way - excellent first post! Welcome to the Forums!

05-25-2009, 05:42 AM	#1
Burmese Bandit Senior Member Join Date: Dec 2008 Posts: 489	Alfa Romeo 136 R.C.25 While researching engines which might have been used by the Axis to design a better fighter and/or bomber in WWII my attention was caught by this Italian engine, which, according to the Wiki (not that I trust it 100%, but it's much more often right than wrong!) says - "...At the time of its first running in 1938 and 1939 it was the most powerful radial engine in the world, generating just less than 1492 kW (2000 hp) on 100-octane fuel." Although the 135 in question is then described as having "...Power output:1177 kW (1600 hp) at Take Off, 1030 kW (1400 CV) at 3200m..." Wiki goes on to say that a variant, the Alfa Romeo 136 R.C.25, had a power output of "...Power output:1765 kW (2400 hp) at 0m, 1360 kW (1850 CV) at 2500m..." TWO THOUSAND FOUR HUNDRED HORSEPOWER AT SEA LEVEL???? If that was true, and it was produced in the very early years of the war, why wasn't it used as the primary engine for thw Wurger - especially the ground attack version??? Did this engine have reliability problems, or production problems, or was it just a case of German Technical Jealousy??? I have searched this forum and the net, but i have not been able to come up with the answers to those questions. Which is why I am asking the very knowledgeable members of these forums - could someone enlighten me on the history and fate of this (on paper at least) world-beating engine of its time?

06-02-2009, 08:04 AM	#4
b0ned0me Junior Member Join Date: Jan 2009 Posts: 2	I can't add much more than you have already found, but I have myself been intrigued by that engine - if for no other reason than it seems to be based on a licence-built Bristol Pegasus 'doubled', which indicates what Fedden might have been able to achieve if he hadn't bought into Ricardo quite so whole-heartedley. I have to say I'm a bit suspicious of that 2400hp number. Not to disrespect the Italians, but could Alfa Romeo really volume-produce an engine early-war that would match a late-war R-3350? Only 150 of these engines were made, and my feeling is that getting an 18-cylinder four-valve radial to 2400hp for testing might have been doable, but achieving the same on a mass-produced engine with standard-issue fuel would be another matter. If that were the case, then the 2400 hp from the 136rc25 would be like the 2200hp from the early Napier Sabre - available from the test bed and the workshop, but not from the factory. [edited to correct stupid typo] Last edited by b0ned0me; 06-02-2009 at 09:09 AM.

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05-25-2009, 04:42 PM	#2
red admiral Senior Member Join Date: Mar 2005 Posts: 434	I'm not sure when the 136 itself was produced but the 135 is from around 1938/39. There were a few initial problems with the 135, mostly relating to the cam ring breaking, but reliability was otherwise good. The Germans did some harsh reliability tests against the BMW 801 and found the 135 to be much better. Its a little bit wider than the 801 but shorter and lighter.

05-25-2009, 07:25 PM	#3
Burmese Bandit Senior Member Join Date: Dec 2008 Posts: 489	AHA! Thanks, Red Admiral... So then, it is as I suspect...the old GERMAN JEALOUSY monster rears its head again... Who can tell me more? I am intending to resurrect my old 'could you have desiged a better warbird' thread around this engine, and I would like more input before I do so.

06-02-2009, 08:42 AM	#5
Burmese Bandit Senior Member Join Date: Dec 2008 Posts: 489	Good point, and by the way - excellent first post! Welcome to the Forums!