BMW132 double available pre-war

If I understand the OP correctly, he/she is proposing an 18-cylinder, twin-row radial engine similar to the R-2180 Twin Hornet engine tested by Pratt & Whitney in 1930?

A twin-row based on Hornet cylinders is the logical, low-risk way to increase horsepower.

Twin Hornet was a twinned Hornet just in name. 14 cylinder engine R-2180 vs. 9 cylinder R-1690.
Plus the neglected thing that Twin Hornet never worked. Unlike the post war 'half R-4360' that also got the R-2180 name, alas it got no costumers

Trying to double output again by bolting together 4 rows was a complex procedure only perfected after WW2. Eventually Wright Turbo-Compound engines provided superlative fuel efficiency for (Cold War) RCAF Argus maritime patrol airplanes, but those corn-cob engines proved such maintenance-hits that they were
unpopular with civilian airlines.

Wright turbo-compound was not the 'corn cob', it used the 18 cyl R-3350 engine as basis. The 'corn cob, Pratt & Whitney R-4360 was a new engine, not rows of existing engines bolted together.

Sure, but AFAIK before the D-series showed up they had fixed the engine, the buffs you mention increased power and reliability, but it was unnecessary to make the Fw190 workable.
https://translate.google.com/translate?sl=auto&tl=en&js=y&prev=_t&hl=en&ie=UTF-8&u=https://de.wikipedia.org/wiki/Focke-Wulf_Fw_190#Fw_190_A-2&edit-text=&act=url

The Fw 190A-2 and A-3 shared the same installaton, for a different engine - 801C vs. 801D. The 801D when introduced with Fw 190A-3 was not reliable enough to meet the prescribed 1.42 ata and 2700 rpm, so these parameters were restricted until the relaibility was fixed by implementing the listed changes to the engine. Restriction was in force from March 1942 to October 1942 (when the listed chages are made). If the engine was operated above the restricted parameters, the engine will overheat.
Hopefuly your German is up to the speed: table
 
Seems one of the few 9 cylinders engines that successfully was twinned keeping the same bore and stroke of the parent engine was the Shvetsov M-71, that without Barbarossa probably would have seen wide scale production, rather than supercharging testing during the war that led to the -73 that powered the B-29 copy postwar.
 
From what I've read, the 802 never matured. That's something engines do after they enter production and respond to problems. Have you read anything about BMW engines of the era? Do you have a copy of Tomo's book? Can you tell me how a two-row engine can have a triple center bearing and no outer bearings to support the prop or supercharger drive and accessories ? Can you tell me how BMW solved the problem of torsional vibration? If you google BMW 139, you get lots of info, some from researched books, and some of them refer to the BMW 139 as a simple 2x132. One even said the Bramo 329 ran at 2,000 hp. But none of the information anywhere seems 100% or even 50% accurate and there are no revealing photos of any kind. It doesn't seem simple to me. Maybe to you. The 801 was an engineering marvel that began in 1938, and you see no reason why an 802 can't enter production by that time. You have a great imagination.
None of that technical info/ knowledge.
All I am saying is that these issues were solved in other designs. Not as 2x copies most of the time but from the experience wit the same engine the Germans licensed in 1929. The OTL succesful designs were mostly succesful in a 5 year timeframe (or failed in that timeframe). Thus, it seems highly possible it could be done from 1933 to 1938, but there is no certainty.
Bmw802 were reputedly within the last phase of development when it lost its already limited priority to jets.
90% of what I know about this subject is from this thread.thanks to all the posters.
 
Seems one of the few 9 cylinders engines that successfully was twinned keeping the same bore and stroke of the parent engine was the Shvetsov M-71, that without Barbarossa probably would have seen wide scale production, rather than supercharging testing during the war that led to the -73 that powered the B-29 copy postwar.

There seems to be plenty of potential in the M-71 engine, take off power was reported at 2000 HP, later increased to 2200 HP with M-71F version. OTOH, the passage from Wikipedia is telling re. this topic:

"The M-71 was developed from the Shvetsov M-70, a failed attempt at a two-row version of the single-row Wright R-1820 Cyclone."
 
There seems to be plenty of potential in the M-71 engine, take off power was reported at 2000 HP, later increased to 2200 HP with M-71F version. OTOH, the passage from Wikipedia is telling re. this topic:

"The M-71 was developed from the Shvetsov M-70, a failed attempt at a two-row version of the single-row Wright R-1820 Cyclone."

I just checked the quotes in Wiki which said " The M-71 of 1939 was the successor to the M-70 and it, too, was not a success." From the ASh-73 Wiki. Wiki is tricky that way, and success is hard to define. The ASh-73 itself was considered a success, but underwent 7 stages of up-grade improvements to slightly less successful major components.

Who knows.
 
Well, presumably this 18 cylinder BMW-138 (and likely a Bramo competitor) would butterfly the OTL BMW-139 (and Bramo-329)? I could see Ju-88 powered by this engine from the start, and the Do-217 too, but really i doubt it could be refitted without major changes to the He-111 or Ju-87, they haven't fitted them with BMW-801 when that became available, they won't fit the larger BMW-138. But at least this might free up lots of Jumo-211s, so they COULD power a Hs-129 variant, last Do-17/Do-215 variants, more possible exports to Romania, Hungary, maybe Italy, Finland etc.

As to the FW-190, it is true that the engine is bigger though apparently not heavier than the OTL 801, BUT imo, with the steady improvements made to the engine just like it happened with the OTL BMW-801, i can still see a fan cooled BMW-138 powering the FW-190 in a slightly larger form from the start in 1939 (hence avoiding redesign like in OTL), and with improvements like improved superchargers and C3 fuel i see no reason with the engine will not give 2000 HP in 1941, so probably the FW-190 is at least as good if not even a bit better compared to OTL, though slightly more expensive to build.

Developed versions though, if made to reach 2200-2400HP without MW-50 could possibly be tempting for He-177 and Ju-288 and other similar two and four engine bomber projects, but with the grotesque politics affecting those projects as we know, nothing would have been granted.
 
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