Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
Eventually they produced the 801, which was in many ways an excellent engine, and Kurt Tank's use of it in the FW190A with the low drag installation was genius. But if the 801 isn't available, then Kurt Tank would design the 190 from the get-go with an inline, as he eventually wound up doing anyway with the D series and the Ta-152.
However, like most new engines, the 801 had a rough start and it took a while before they got it running reliably. And ultimately it was limited by poor supercharging for high altitude work, and all the various experiments with multi-stage supercharging, turbocharging etc. didn't enter use. And similarly, none of the follow-on work on bigger radials (802/803/...) worked out either. So in a way it was a huge amount of resources on radial R&D that ultimately resulted in only one good design produced in numbers. And even that one had a relatively short lifetime due to the reliability issues when it was first introduced, to being superseded by the inline powered FW190D only a couple years later.
From a fuel supply perspective the 801 was also tricky, requiring C3 to develop decent power. And as C3 took much more resources to produce than B4, it further exacerbated Germany's critical situation wrt aviation fuel.
I think the critical question is, what would the resources not being spent on radial R&D have been used for instead? Turbojets, though it doesn't seem realistic to decree in the mid-30'ies that BMW should drop piston aviation engines to focus on jets? Auxiliaries, like supercharger and turbocharger development for Daimler/Junkers inlines? Kommandogerät for DB & Jumo engines? Move staff over to Daimler and Junkers to develop and produce their designs? Or license produce Daimler and/or Junkers inlines? Or would German aircraft designers have three families of inlines to choose from, if BMW would have developed their own inline engines?
For the alt-Fw190 to materialize with a V12 in the nose, there needs an understanding in the RLM that there will be a suprplus of the V12s in the very near future, otherwise the FW fighter project has a good chance to be axed. So we'd need for BMW - they are big enough to pull this one off, especially after the Bramo was bought - to make a competitive engine (a good V12 for this scenario).
Me, I'd go with the a big V12 instead of the BMW 139/801, talk 40-45 liters. As a follow-up, start thinking about the jet engines.
Fw 190A was not superseded by the 109D after only a couple of years, but after more than 4 years.
One good design > a few mediocree designs, IMO.
Okay, roger that.My argument is that while the 190A entered service in August 1941, it took a while until the issues with the engine were resolved, and it wasn't until maybe 1942 it really hit its prime. And by early 1944 it was already no longer on par with the latest Allied fighters.
Take for instance the BMW VI. A V-12 producing 550/750 hp (max continuous/takeoff) in 1926, with a weight of 510 kg. But they threw it away, licensed the P&W radial and produced an improved version, the BMW 132. Which admittedly was a successful engine, powering the Ju-52 among others. But in a time when aviation technology was developing rapidly, the 132 produced about as much power at about the same weight as the VI. So they had spent 7 years taking what, in terms of power/weight and max power, was a big sideways step rather than forward.
So what if they instead of going down the radial route had doubled down on developing the VI platform? Admittedly an inline engined Ju-52 would be pretty funny looking! Though the VI was a large volume engine, 47L, in the size class we're interested in, I don't think it could be adapted for the power levels required for a mid-late WWII fighter. They could have made another engine with the same volume (perhaps reusing some parts and tooling?) but much sturdier and made for high boost ratio, 4V/cylinder, fuel injection, higher rpm, and all that jazz.
Kommandogerät for DB & Jumo engines?
The BMW VI peaked at 1650rpm?
Stress in the reciprocating and rotating parts go up with the square of the speed.
AM-35 gained 300kg and ran at 2050rpm.
27 liter engine running at 3000rpm or 47.7 liter engine running at 2050rpm?
Or 36.7 liter engine running at 2750rpm?
I get a little lost when people talk about "in house Knowledge" of a particular type of engine.
This thing was two WW I cylinder banks mounted on a common crankcase. Pretty up to date in 1918.
In 1933????
Germany had been prohibited or severely restricted in aircraft and and aircraft engine development during the 1920s.
Looking only at the results, the engine was proposed from about 1939 and had a short development before production. There seems little doubt that the engine was underdeveloped before its introduction to service. However, in the Fw 190 it gave the RAF and the Allies a big problem, right from the start. The initial development timescale was too optimistic.
Well, the BMW VI didn't have a reduction gear and didn't have a supercharger (sea level was about as good as the power got) so there was going to be a weight gain no matter what.I'd say that nobody is under illusion that the 'no free lunch' rule is abolishedThe 'BMW-35' will certainly not be as light as the BMW VI, same as Griffon was much heavier than Buzzard, or Jumo 213 than 211.
There were other things that limited RPM but the point about the way gasoline burns remains.We can recall that 44.5L DB 603 run at 2700 rpm, while AM-38F run at 2350 - IOW, not everything is bleak wrt. RPM vs. capacity.
Well, part of the problem here was duplication of effort. The BMW 116 was in direct competition with the Jumo 210 and the BMW 117 was in competition with both the DB 600/1 and the Jumo 211. Perhaps Germany got it wrong but they did not have an inexhaustible supply of engineers. Perhaps BMW should have been put to work on a BMW 118 to compete with the DB 603?BMW was moving on. They designed the small V12 (BMW 116) and bigger one (BMW 117), but were ordered by the RLM to stop the liquid cooling engine projects, and make air-cooled engines from now on.
Have the BMW make a new engine (we can recall that BMW designed 3 separate engines in the late 1930s).Every Piston engine was a series of compromises. Some designers stuck with what they knew and branched out slowly. Sometimes they stuck with an old engine too long.
Do you gamble on a new engine or spend increasing amounts of time and money on small improvements to an old engine?
There is certainly no point in the 116. The 117 makes better sense, especially if it can be had by the time the DB 601 is available. However, the a big V12 (~45L) gets my vote, indeed a competition for the DB 603.Well, part of the problem here was duplication of effort. The BMW 116 was in direct competition with the Jumo 210 and the BMW 117 was in competition with both the DB 600/1 and the Jumo 211. Perhaps Germany got it wrong but they did not have an inexhaustible supply of engineers. Perhaps BMW should have been put to work on a BMW 118 to compete with the DB 603?
The BMW 801 fulfilled a need, it was a way to get a 1500-1600hp engine into service for larger aircraft than the DB 601 and Jumo 211 could power (at the same point in time) the extra cylinders meant that its roughly 20% large displacement would make that easier, the air cooling would make it a bit harder.
I am not sure about a 3rd 34-35 liter V-12. If you need more engines build another factory for the DB 601 or Jumo 211 and simplify spare parts and training.There is certainly no point in the 116. The 117 makes better sense, especially if it can be had by the time the DB 601 is available. However, the a big V12 (~45L) gets my vote, indeed a competition for the DB 603.
Part of the problem is when, the Jumo 211 and DB 605 were already the size of the Griffon (or close) so how far can you go with the 'simple' V-12 before you get into diminishing returns. This was the reason for all the 24 cylinder engines. They gave the promise of higher rpm which the big V-12s could not match. Promise and delivery are different.This is why the big V12 gets my vote - to bring the level of power that Jumo 211 or DB 601 are likely to struggle to deliver.
You can note that I advocate for a really big and simple V12 in this thread, ie. something much bigger than either the 601 or 211.I am not sure about a 3rd 34-35 liter V-12. If you need more engines build another factory for the DB 601 or Jumo 211 and simplify spare parts and training.
The British had the Hercules and Merlin to compete with each other. The Sabre, Vulture and Centaurus were the next step. (and Deerhound)
Part of the problem is when, the Jumo 211 and DB 605 were already the size of the Griffon (or close) so how far can you go with the 'simple' V-12 before you get into diminishing returns. This was the reason for all the 24 cylinder engines. They gave the promise of higher rpm which the big V-12s could not match. Promise and delivery are different.
Radials isn't a terrible choice, but getting any radial to run in a close ultra streamlined cowl is hard business. US failed on many attempts..I think the critical question is, what would the resources not being spent on radial R&D have been used for instead? Turbojets, though it doesn't seem realistic to decree in the mid-30'ies that BMW should drop piston aviation engines to focus on jets? Auxiliaries, like supercharger and turbocharger development for Daimler/Junkers inlines? Kommandogerät for DB & Jumo engines? Move staff over to Daimler and Junkers to develop and produce their designs? Or license produce Daimler and/or Junkers inlines? Or would German aircraft designers have three families of inlines to choose from, if BMW would have developed their own inline engines?
My view is that that the really big and simple V12 is not quite as simple as it appears.You can note that I advocate for a really big and simple V12 in this thread, ie. something much bigger than either the 601 or 211.
Thank you.My view is that that the really big and simple V12 is not quite as simple as it appears.
Griffon, 36.7 liters...........168mm stroke.............2750rpm....................3025ft/min piston speed.
DB 605, 35.7 liters...........160mm stroke............2800rpm.....................2940ft/min piston speed
DB 603, 44.5liters............180mm stoke..............2700rpm.....................3188ft/min piston speed
AM-38, 46.7liters.............190mm stroke...........2350rpm.....................2929ft/min piston speed, not counting the longer stoke in the other cylinder bank.
If you have to reduce the rpm you are not getting quite the power the increase in displacement suggest.
Yes the Griffon cheats by using higher octane fuel but but the Griffon is 39.2% larger than the Merlin but then cuts the rpm to 91.66%
I have said many times that power to weight is more important than power per liter and perhaps the big engines show up better this regard.
I would note that small engines that perhaps could run faster (and still keep the 3000ft/min) piston speed can do as well as the 27-37 liter engines per liter but they tend to run higher friction losses.
The German and Soviet engines had problems due to raw material shortages so it is difficult to figure out engine life and some other problems. The Big V-12s had problems.
The smaller 24 cylinder engines had problems of their own. Vibration problems with many/most/all? of these engines were much greater than anticipated in 1939-40.
P & W with the R-4360, take the R-2800 cylinders, only put 7 on a row, use four rows, what could go wrong???
4 years later and few dozen test engines and..........................
Wright with the R-3350, Take the R-2600 and add two cylinders per row, easy peasy right.....................................
Just showing that things were not a simple as many people believed at the time. They thought they had a easy way to increase power using proven components, just add more.I'm not sure what these radials ad 24 cyl engines had to do with V12s.
Any insight on why in late 1930s Germans should look at Hispano - of all engines - as an inspiration on how to make big (and bigger) V12 engines?Just showing that things were not a simple as many people believed at the time. They thought they had a easy way to increase power using proven components, just add more.
If you want to stick with V-12s look at the Hispano and what it took to get more power out of it.
Actually getting more power is easy, just like a race car, it is making more power and finishing the race that is the trick.
Every time you increase the RPM you can wind up with a number of new vibration patterns
Simply scaling things up can also set lose all sorts of vibration problems. The Vibration problems can show up as all kinds of fatigue cracks/breakages hours into the test runs.
My view is that that the really big and simple V12 is not quite as simple as it appears.
Griffon, 36.7 liters...........168mm stroke.............2750rpm....................3025ft/min piston speed.
DB 605, 35.7 liters...........160mm stroke............2800rpm.....................2940ft/min piston speed
DB 603, 44.5liters............180mm stoke..............2700rpm.....................3188ft/min piston speed
AM-38, 46.7liters.............190mm stroke...........2350rpm.....................2929ft/min piston speed, not counting the longer stoke in the other cylinder bank.
I have said many times that power to weight is more important than power per liter
The Big V-12s had problems.
The smaller 24 cylinder engines had problems of their own. Vibration problems with many/most/all? of these engines were much greater than anticipated in 1939-40.
P & W with the R-4360, take the R-2800 cylinders, only put 7 on a row, use four rows, what could go wrong???
4 years later and few dozen test engines and..........................
Wright with the R-3350, Take the R-2600 and add two cylinders per row, easy peasy right.....................................