Switch the Axis and Allies planes during WW2 (1943 Western Front)

[dobbie]

I just dont see the swap doing either side much good. The reason America developed long range fighters and bombers is because we needed them to reach the targets, and were fighting a different sort of war than what Germany was. The German industry was concentrating more on tactical strikes and ground support. For the US to reach the targets we were after required a different philosophy.

 

[Shortround6]

German 97 octane avgas was equal to Allied 100/130 octane avgas.

The German 96/97 octane avgas may have gone through a number of different formulas/mixes over 3-4 years. at least two.

I am not sure that they ever changed the name but the fuel used in the DB 601E may not have been the same fuel used in the last models of DB 605s or the BMW radials.

Germans were making about 2/3 of their fuel in the C3 type and were seeking ways to increase that percentage.

 

[Tante Ju]

Reading through US fuel reports, wasn't C-3 basically just a post-processed B-4...?

The way I understand it, you had B-4 as a base after the end of the synthetic process, and then you could decide whether to put it through yet another chemical process and arrive at C-3, or just leave it as it was and have B-4.

 

[Civettone]

In that case, it seems to me strange enough that the Germans, more or less to the ends of the war, remained stuck to B4 fuel and engines capale to burn it, when they are stockpiling large amounts of C3 fuel with which they did not know what to do (see for example the mass production of the Jumo 213E instead of the much more powerful B and C versions). Since switching from a B4 capable to a C3 dedicate version of an engine, seems to give around 20-30% more power, not using it, while they could produce as much as they want of it, seems a suicide decision.

B4 was easier to produce. In 1943, there was three times more B4 than C3. They used their C3 fuel for a lot of planes, especially those powered by the BMW 801 as well as the DB 605AS(B).

The confusion concerning different octane levels stems from a different lean/rich mixture designation.
Kris

 

[Dogwalker]

B4 was easier to produce. In 1943, there was three times more B4 than C3.

So, switching aircrafts, since the entire first line of Allied aircrafts in 1943 required at least C3 fuel...

They used their C3 fuel for a lot of planes, especially those powered by the BMW 801

That, in the FW190D, was replaced by the B4 fuelled Jumo 213E (and B4 fuelled were the production versions of the DB603), showing a certain tendency toward saving the C3, instead of using only it.

 

[altsym]

With the DB 605AM they still got 1800ps with B4 1850ps with the DB 605ASB with B4. Pretty good numbers from a low octane synthetic fuel.

 

[Civettone]

Yes, you are right on both accounts.

Though, I wonder if it was mere saving of C3 on the Jumo 213 and DB 603. Maybe there were some technical issues? Fact is that none of these engines flew with C3, but stuck to B4 and MW 50, despite clear advantages in using C3 and MW 50, like the DB 605ASC which produced 2,000 hp. This applied to the DB 603 and Jumo 213 would have given them engines far above 2,000 hp.

Kris

 

[Tante Ju]

That, in the FW190D, was replaced by the B4 fuelled Jumo 213E (and B4 fuelled were the production versions of the DB603), showing a certain tendency toward saving the C3, instead of using only it.

The Jumo 213A of the 190D used B4 also... I suppose the radial BMW 801D used C-3 because of the worse ignition characteristics of radial engine (higher/less controllable cylinder temperatures?). Early 801 used B4.

 

[Dogwalker]

Using higher octane fuel has not drawbacks. It could be used in engines made for lower octane fuel without problems, and if you want to reach higher power, it solves a lot of problems.
So, the only reason to not use it to it's full potential (with dedicated engines, with higher compression ratio and/or boost), to me, it's the more difficult production of the fuel, and so the fear to remain without it. If you put a 87-octane rated engine in production, you can use whatever you have in the tanks. If you put a 100-octane dedicated engine in production, you can use only 100-octane fuel or having it grounded.

 

[altsym]

Engine will always make more horsepower with less octane giving that the timing (cam ignition) A/F mixtures remain constant. Low octane fuel = less volatile which means you get a more complete even burn in the cylinders. But that's when modern computer controlled engines come in handy, or very careful tuning.

The JUMO 213E made 2,050 PS with MW-50 B4, and a 350ps boost when the GM-1 was used at altitude, also on B4. Some DB 605 series engines can use either B4 or C3, the rated octane use can be switched with a simple screwdriver.

 

[Civettone]

I said that in 1943 there was three times more B4 than C3, as we were talking about a 1943 scenario. However, when we are talking about the Jumo 213E and other late-war engines, the situation is different: most fuel was C3. However, until late 1944, MW 50 could only be used in combination with C3. That must have used up quite a bit of C3.
However, by late 1944, Daimler Benz modified its engines in such a way that MW 50 could be used with B4. Around the same time, production of the Fw 190A was turning towards the Fw 190D and Ta 152. For all these reasons, I would expect a drop in C3 consumption from 1945 onwards. This seems to be confirmed by the new DB 605ASC or DC engines which worked with C3 plus MW 50. As such, I would expect the same to happen with the Jumo 213s and DB 603s. Yet, none were operational.

Only the DB 603G and the Jumo 213E-0 used C3 fuel. None of these two engines entered service. Because of C3 shortages? I doubt it.

Kris

 

[Dogwalker]

So what's the reason? That all the last generation of German engines, for example, could not mechanically bear an higher booost than those permitted by B4 fuel?
It seems really weird.

 

[Civettone]

Also found this. Too bad Vanir got himself banned. Knows a lot.

http://www.ww2aircraft.net/forum/engines/why-c-3-fuel-db-605-a-30055-2.html#post829876


Kris

 

[Civettone]

So what's the reason? That all the last generation of German engines, for example, could not mechanically bear an higher booost than those permitted by B4 fuel?
It seems really weird.

I know and I find it very puzzling myself. In that post by Vanit, he says that the RLM wanted all fighters to use B4. I guess as a matter of precaution: B4 engines can always use C3, but not the other way around.
And in the end, all those BMW 801s and DB 605AS/ASMs used C3. So why not the DB 603 and Jumo 213? I honestly do not get it !

Kris

 

[altsym]

Well certainly not all DB 605ASM's used C3 exclusively. There photographic proof in various publications of the ASM engines using B4. Also, C3 DB series engines can use B4 fuel, it was a simple change in the magnitos with a screwdriver IIRC ( or perhaps the supercharger? I have to re-check). The problem with C3 was that not only were the depots getting bombed, but the factories making the aromatics synthetics required for the production of C3. Without those, C3 is a no-go.

 

[stona]

So what's the reason? That all the last generation of German engines, for example, could not mechanically bear an higher booost than those permitted by B4 fuel?
It seems really weird.

Because they were developments of earlier engines not originally designed to run at these pressures.The Germans for many reasons, not all to do with problems of supply, had fallen well behind the game. There were all sorts of technical problems with almost all the Daimler Benz engines after the 601, many of which were never properly addressed.

Really many of the late series engines were what we English like to call "bodges".

It's interesting that some people are speculating about an allied jet in the Me 262 in this scenario. The jet engine was not a German invention. We had them first but for a variety of reasons did not develop them in time for the war. We could have had a jet aircraft in combat mid war (for the Brits, late for the US!) but failed to do so.

Cheers

Steve

 

[Dogwalker]

I know and I find it very puzzling myself. In that post by Vanit, he says that the RLM wanted all fighters to use B4. I guess as a matter of precaution: B4 engines can always use C3, but not the other way around.
And in the end, all those BMW 801s and DB 605AS/ASMs used C3. So why not the DB 603 and Jumo 213?

To answer to an earlier question, there were surely shortages of C3 fuel in late war for Germans, even if the mix of production was now 2/3 C3 or more, as there were shortages of any form of fuel. An aircraft capable to use B4 could at least take off with all that was available, an aircraft that needs C3, had to ask to Allied bombers to wait for a moment, since he got the right fuel.

 

[Ascent]

I'm not an expert but I believe the Italians had some very good fighters around this period but had a poor industrial base to actually get them into service properly. What would the Allies be able to do with these with their manufacturing muscle?

 

[Civettone]

Well certainly not all DB 605ASM's used C3 exclusively. There photographic proof in various publications of the ASM engines using B4. Also, C3 DB series engines can use B4 fuel, it was a simple change in the magnitos with a screwdriver IIRC ( or perhaps the supercharger? I have to re-check). The problem with C3 was that not only were the depots getting bombed, but the factories making the aromatics synthetics required for the production of C3. Without those, C3 is a no-go.

The manuals are clear about it. It was not allowed to use MW 50 without C3. They could use it but at risk of ruining the engine. İt was only cleared at the end of 1944 after DB introduced new spark plugs. So what you saw, is either an emergency measure in 1944 or with improved engines in 1945.
The change with a screwdriver you are referring to, is turning the DB 605ASB into an ASC (or vice versa), which was authorized around March 1945 IIRC. Again, a similar story, the DB 605ASB could get to 1.8 ata only with B4 and MW 50. It could work perfectly with C3 but it would not have changed performance, merely increased the security. Only a ASC with C3 and MW 50 could get to 1.98 ata.

And yes, there were shortages of all fuel. But C3 production was not more affected by the bombings than B4 production.

Kris

 

[Dogwalker]

And yes, there were shortages of all fuel. But C3 production was not more affected by the bombings than B4 production.

They never managed to produce only C3, so an aircraft that needs C3 will suffer more shortages than one capable to use B4.