R-R militarized 'R' engine: one engine to rule them all?

Buzzard was first, designed as a scaleup of the Kestrel at 2240 cubic inches in 1927
On 77 Octane, did 825hp@2000rpm. 1448 pounds.
For a long time I have thought that a “Buzzard II” was a huge missed opportunity for the UK. Something with the same general scheme as the buzzard but designed to the limits of thirties tech as the Merlin was OTL should have arrived in WW2 as a monster motor. It certainly wasn’t anything excessive large relative to the Jumo, Daimler or Hispano-Suiza contemporaries. But instead of “more power from same size” RR and Bristol and even Napier seemed to decide on first “same power from smaller size” and then “MUCH more power from frabjous complexity” because what could be better for war than relying on 140,000 parts in a 48-cylinder Z-layout two-stroke stratified charge sleeve-valve engine with 3 crankshafts and 11 carburettors?

A nice big V-12 should IMO have been a very tempting prospect but for some reason it just didn’t happen. Maybe related to the hyper engine lunacy in the US, if someone important thought it was much more important to get more power out of a smaller unit than to just have the maximum possible power.
 
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The Merlin was a private venture from Rolls Royce and was enough of a gamble that an engine of that 27 litre size would be chosen by a airframe manufacturer being so much larger and heavier than the typical mid 1930's service standard. A 36 litre one was not going to find a buyer in the market of that day. Governments might ask for engines of the future but Rolls Royce had to sell it to the commerce of the day to recoup costs. If all went well they would have been happy to sell a few hundred. The 21 litre Peregrine was the size of the day. A 27 litre Merlin was an incremental step. A 36 litre Griffon/Buzzard would have been a step too far for a business that relied on current sales.
 
The Merlin was a private venture from Rolls Royce and was enough of a gamble that an engine of that 27 litre size would be chosen by a airframe manufacturer being so much larger and heavier than the typical mid 1930's service standard. A 36 litre one was not going to find a buyer in the market of that day. Governments might ask for engines of the future but Rolls Royce had to sell it to the commerce of the day to recoup costs. If all went well they would have been happy to sell a few hundred. The 21 litre Peregrine was the size of the day. A 27 litre Merlin was an incremental step. A 36 litre Griffon/Buzzard would have been a step too far for a business that relied on current sales.

The 36 litre HS 12Y engines were widely used from mid-1930s, not only in France. 32.5 litre Isotta Fraschini was also widely used, from early 1930s.
And even those were not the engines with greatest displacement, those would've been the BMW VI and it's versions, 47 liter engines, again widely used in 1920s/30s. Those were further developed in Soviet union by the Mikulin design bureau into M17/M34/AM35/AM38 etc engines.
People were also making, back in 1930s, 18 cyl engines, liquid cooled like the I-F Asso 750 (48 liters).
 
Would a derated R work in tanks like the Meteor ?
It doesn't have the design of the Griffon, so yes, it should work.

For a long time I have thought that a “Buzzard II” was a huge missed opportunity for the UK. Something with the same general scheme as the buzzard but designed to the limits of thirties tech as the Merlin was OTL should have arrived in WW2 as a monster motor. It certainly wasn’t anything excessive large relative to the Jumo, Daimler or Hispano-Suiza contemporaries. But instead of “more power from same size” RR and Bristol and even Napier seemed to decide on first “same power from smaller size” and then “MUCH more power from frabjous complexity” because what could be better for war than relying on 140,000 parts in a 48-cylinder Z-layout two-stroke stratified charge sleeve-valve engine with 3 crankshafts and 11 carburettors?

A nice big V-12 should IMO have been a very tempting prospect but for some reason it just didn’t happen. Maybe related to the hyper engine lunacy in the US, if someone important thought it was much more important to get more power out of a smaller unit than to just have the maximum possible power.
Because not many people bought engines that powerful back then. The heaviest and most powerful engines of the day were the Jumo 204, Buzzard, and Condor. Only a few aircraft used them, and only 2 of them had more than 10 built (the Short Singapore and Hawker Horsley, both with the Condor). All 3 engines also had scaled-down versions which were much more widely used- the Jumo 205, Buzzard, and Eagle. That's most likely why they didn't bother- there wasn't much business in that big of engines at the time.

Those were further developed in Soviet union by the Mikulin design bureau into M17/M34/AM35/AM38 etc engines.
The AM-34 and developments were a clean sheet design, having nothing in common with the M17/BMW VI except bore and stroke.
 
The AM-34 and developments were a clean sheet design, having nothing in common with the M17/BMW VI except bore and stroke.
Not so clean, since it still used Master-Slave connecting Rods, with inequal displacement between banks, vs Fork and Blade that allows a shorter block like the M-S, but has the same displacement on each block, much easier on the crank.
 
IBecause not many people bought engines that powerful back then. The heaviest and most powerful engines of the day were the Jumo 204, Buzzard, and Condor. Only a few aircraft used them, and only 2 of them had more than 10 built (the Short Singapore and Hawker Horsley, both with the Condor). All 3 engines also had scaled-down versions which were much more widely used- the Jumo 205, Buzzard, and Eagle. That's most likely why they didn't bother- there wasn't much business in that big of engines at the time.
The Buzzard and 204 were late twenties engines, the Condor a WW1 engine. By the time the Merlin was being designed there were 30L+ V-12s on the drawing boards or running at Daimler, Hispano-Suiza, Isotta-Fraschini, Mikulin, probably Jumo and maybe a few other places. The Merlin (and Allison) worked out well enough but I don’t think it’s ASB for RR to have come to the same conclusion as all of these other firms and developed the Buzzard size rather than a slight growth of the Kestrel size into the PV-12 and then trying for a double kestrel etc. as OTL.
 

FBKampfer

Banned
It's my understanding that the R wasn't running ANY gasoline in its fuel blend when it's numbers were pulled.

First, we need to establish an accurate estimate of its power output on 87 octane avgas, and then we need to establish what needs to be done to detune it.

Before this is done, nothing is meaningful.

I'll get back to you when I'm done figuring energy density of the fuels.
 
It's my understanding that the R wasn't running ANY gasoline in its fuel blend when it's numbers were pulled.

First, we need to establish an accurate estimate of its power output on 87 octane avgas, and then we need to establish what needs to be done to detune it.
...

You're quite right that R used special fuel blend, it made possible high boost (almost +18 psi) to be used. More boost = more power. As gearheads will know, there was no 130 grade fuel back in late 1920s/early 1930s. Using 87 oct fuel will mean much lower boost - looking at 1st Merlins and late Kestrels, it is, say, +6 psi to +6.5 psi maximum (1.45 to 1.50 ata in German parlance)?
High RPM (3000 early on; 3200 and increased boost for later versions that went beyond 2300 HP; more RPM = more power) on such a long stroke (almost 170 mm) will also need to be lowered, we don't want engines disintegrating in mid-air. Other big 4-valve per cylinder V12 engines: Buzzard went to 2300 rpm max (used 77 oct fuel), DB 601 from 2400 to 2800, DB 605 from 2600 to 2800, Griffon to 2750 rpm, so my best guess is that we can have 2600 rpm for an early 'R minus'?

Thus we have a 36.7L engine, 4 valve per cylinder, that does 2600 rpm and uses 1.45-1.50 ata. DB 601E (33.9L) was good for 1320 PS at it's rated altitude (4.9 km, ~16100 ft) on 2700 rpm and 1.42 ata; 1250 PS on 2500 rpm and 1.30 ata; 87 oct fuel. DB 605A (35.7L) was making 1250 PS at 19000 ft on 2600 rpm and 1.30 ata.
I'd say that my estimate of 1300 HP at 15000-16000 ft for the 'R minus' is on a conservative side.
 
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