Alt 'day' fighters for Luftwaffe, 1937-45

[Nell_Lucifer]

I don't think DB or Jumo would abandon any kind of work on diesel engines, they are to juicy to pass on... plus, weren't the guys working on diesel engines part of a different branch? Even if you were to stop all work on diesel engines I am not sure if it would have helped the guys working on petrol ones.

Perhaps focusing solely on 1 or 2 engines would have been better, or maybe award any diesel engine contract to another company that is not DB, Jumo or BMW... Deutz? MAN? Maybach? Porsche?

Anyway! So, I've been thinking a bit on some of the reasons the Me 163 was not successful (ignoring the obvious hazardous to work with fuel) and that being flight time, restrictive cockpit and lack of a proper landing gear...

What if instead of the Me 163 being the rocket propelled plane it was the Me 262? At least until it can get working, quality engines?

While the Me 163 would get a HeS 3b or 6 engine instead of its rocket one? Light enough that the relatively low power centrifugal jet engine would still propel the plane to speed in the range of 800 km/h but with much higher endurance?

This rocket propelled Me 262 would probably not suffer from the OTL bane of the original 262 - long airfields - or the original Me 163's 7 minute of fuel. This also means it could enter into service by 1942 instead of 1944.

 

[ric350]

German C3 was of higher octane rating than what the RAF was using at BoB.

Well actually not. While C3 fuel was suppose to be delivering 130 octane, it actually tested at more like 95. That’s why I included that quote in my previous post. The Germans were forced to run at much lower manifold pressures than the Wallies. Of course the Germans compensated somewhat with various injection methods, but they could only be used for limited durations.

The RAF was using US aviation fuel rated/tested at 100 octane in the BoB ( while Germany was mostly still using 87, hence their surprise at the better British aircraft performance).

ric350

 

[CaptainCalvert]

Thanks Tomo Pauk for the link on post 248.
On nickel and cobalt, coatings would have helped improve the durability and combustion temperature (which improves engine efficiency) and while not as good (or reliable) as when used throughout the component, would allow limited stocks to go further.

 

[tomo pauk]

Well actually not. While C3 fuel was suppose to be delivering 130 octane, it actually tested at more like 95. That’s why I included that quote in my previous post.

You do know that there is such thing as lean and rich rating, right?

 

[ric350]

Yup, but across all power settings the Germans struggled to get the power that the Wallies were getting. If I understood that document on German fuel production (and that’s questionable) one of the issues was limitations of the synthetic coal derivative fuels and associated additives. So even if the Germans had Merlin’s and R2800s they still wouldnt have matched the Wallies.

Check out the YouTube channel called “Gregs Airplanes and Automobiles”. In his various WW2 aircraft videos, he posts very interesting power curve chart comparisons, many from military tests of the period. The Germans are typically on the back foot, especially at high altitudes.

ric350

 

[tomo pauk]

Yup, but across all power settings the Germans struggled to get the power that the Wallies were getting. If I understood that document on German fuel production (and that’s questionable) one of the issues was limitations of the synthetic coal derivative fuels and associated additives. So even if the Germans had Merlin’s and R2800s they still wouldnt have matched the Wallies.

I don't get the comment 'yup'.

Perhaps a clarification is needed wrt. rich and lean rating.
For example, the Allied 100/130 grade (not 'octane', grade; sometime called just '130 grade') from mid-1942 was of 100 grade in lean rating, 130 grade in rich rating. Rich ratings were used for high-power settings, lean ratings were used for low-power settings, where fuel economy is more important than the burst power. German C3 fuel was, per Allied measurements, 95/130 grade (lean/rich), depending on time ( a bit worse back in 1940, a bit better in 1944).
British 100 oct was at 100/120 grade back in 1940. The 150 grade was 100/150 grade actually; post-war, Americans went with 115/145 grade, in order to increase the lean rating, and to avoid fouling of the spark plugs as it was the case with 150 grade due to the very high lead content.

Synthetic fuel plants were prime source of the German aviation gasoline, whose main problem was that it was not able to keep with demands of quantity, rather than those of quality. Note that in the continental USA, training and transport aircraft were still using 91 oct fuel by a great deal - it was much cheaper and less time-consuming to produce that than the 130 grade, that was required for frontline aircraft across the globe.

Rest assured, if the Germans have had Merlins and R-2800s, they would've been eeking every HP out of them just like the UK and USA did.

Check out the YouTube channel called “Gregs Airplanes and Automobiles”. In his various WW2 aircraft videos, he posts very interesting power curve chart comparisons, many from military tests of the period. The Germans are typically on the back foot, especially at high altitudes.

Do you know why Germans were at the back foot at high altitudes?

 

[marathag]

Rest assured, if the Germans have had Merlins and R-2800s, they would've been eeking every HP out of them just like the UK and USA did.

One thing the Germans did do better, was with the automatic engine controls, rather than all the work a P-47 pilot had to worry about keeping the engine and turbo happy at WEP

 

[tomo pauk]

One thing the Germans did do better, was with the automatic engine controls, rather than all the work a P-47 pilot had to worry about keeping the engine and turbo happy at WEP

Times two for the P-38

 

[Horton229]

Kill off the 222 and 223 as early as 1939?

I know the Jumo 222 was a failure. However, I wonder if Jumo have less on their plate they could make a better fist of it. It might be impossible due to the lack of strategically important alloys, or just the complexity. However, this engine would be just a game-changer for the LW in terms of power it might be worthwhile pursing.

 

[mack8]

Unfortunately, the member that made the post you are referring to it was always ... economical with providing his sources.
But then, on C3 fuel, the finally de-bugged DB 605A in 1944 was supposed to do 1.7 ata on C3 fuel and 'dry' (1.8 ata with MW 50 reliably), so 1.58 on C3 for the DB 601E might not be that hard to do. We will need the better valves and lubrication for these boost levels, though.

The issue of improving the high-alt performance still stands.
Perhaps the greatest challenge for the Allies would've been that DB does only the 601 line (it should be doing the power levels more than comparable with Merlin, at all altitudes providing good S/Cs), axes the 603 and 605, and jumpstarts their jet engines program?

Just an idea i explored today, let's assume the germans somehow have enough C3 fuel to power all their fighter engines at least (probably this requiring some oil/fuel ATL, finding those extra oilfileds, getting more oil from Ploiesti etc. so with more natural oil perhaps the syntethic production could focus more on C3). If the 601E and 605A and BMW-801C-2 are designed to run on C3 fuel, will that allow then to run at 1.42 ata from the start, or it will still not be possible?

Having enough C3 fuel at least will give an overall boost in performance and power compared to what the US /UK was capable of, they were running most of their engines later in the war at +18, 21 even 25psi and whatever the US equivalents are which i understand is equivalent to 2,2 to 2,7 ata ( still have not come to grips to psi, ata and inch Hg conversions), while most boosted german engines were running about 1,8 ata, with very few cleared for 2 ata.

And yeah just couple of lines about the jets, as you know the DB007 was needlessly complicated and i don't think it could have ever worked in those days, so perhaps it's best they should just upscale a more "normal" configuration like 003 or 004 to whatever size it needs to give the 1400kgf as per requirements and go from there. Same with the HeS011 actually, again overcomplicated, best to just scale up the HeS006 to give the required 1300kgf. Or just make it a centrifugal type, not both axial and centrifugal on the same frigging engine! As i understand the HeS-006 was quite good but was passed over.

And if the 006 was decent as it's claimed to be it should have been upscaled to a 1300kgf design from the start, rather than duplicating 003/004 powers, which is one of the reasons it was passed over.

The BMW-003 was also a failure in the beggining, i don't know what it takes to at least get it to a functionality level roughly on part with the contemporary Jumo-004.

So overall in an ideal Luftwaffe jet world they would have the 800 kgf 003, 900kgf 004, 1300kgf 011 or 006 and 1400 kgf 007 to mix and match for jet fighters and bombers.

 

[mack8]

The Germans should have been doing something like Fairey's Monarch, huge displacement, 51L vs 35L? of the DB605, and not have to worry about the high RPM issues.
Reliable 2000-3000 HP.

Well they had the Jumo-222 roughly that size, but they flunked it's development as you know, it was never good enough for them and they kept asking more power of it.

 

[mack8]

I don't think DB or Jumo would abandon any kind of work on diesel engines, they are to juicy to pass on... plus, weren't the guys working on diesel engines part of a different branch? Even if you were to stop all work on diesel engines I am not sure if it would have helped the guys working on petrol ones.

Perhaps focusing solely on 1 or 2 engines would have been better, or maybe award any diesel engine contract to another company that is not DB, Jumo or BMW... Deutz? MAN? Maybach? Porsche?

Anyway! So, I've been thinking a bit on some of the reasons the Me 163 was not successful (ignoring the obvious hazardous to work with fuel) and that being flight time, restrictive cockpit and lack of a proper landing gear...

What if instead of the Me 163 being the rocket propelled plane it was the Me 262? At least until it can get working, quality engines?

While the Me 163 would get a HeS 3b or 6 engine instead of its rocket one? Light enough that the relatively low power centrifugal jet engine would still propel the plane to speed in the range of 800 km/h but with much higher endurance?

This rocket propelled Me 262 would probably not suffer from the OTL bane of the original 262 - long airfields - or the original Me 163's 7 minute of fuel. This also means it could enter into service by 1942 instead of 1944.

Imo if there was any room for a Me-163 aircaft would have been something like the Lippisch P15 or P20 configurations, with one 003 or 004 jet engine, complementing the Me-262 in a sort of high low mix, and displacing the He-162. Though while the 163 airframe had very good flight characteristics, i don't know if they will be largely retained if a jet engine is fitted, there will be a bulkier fuselage and increased weight i think.

 

[tomo pauk]

Just an idea i explored today, let's assume the germans somehow have enough C3 fuel to power all their fighter engines at least (probably this requiring some oil/fuel ATL, finding those extra oilfileds, getting more oil from Ploiesti etc. so with more natural oil perhaps the syntethic production could focus more on C3). If the 601E and 605A and BMW-801C-2 are designed to run on C3 fuel, will that allow then to run at 1.42 ata from the start, or it will still not be possible?

Germans having enough of the C3 for all of their fighters will require some nasty handwaving

BMW 801D was running on C3 fuel from the get go. It was still restricted both in rpm and boost until the improved spark plugh were found for it, and until BMW came out with chrome-plated valves, etc. See here.
Hopefully DB can sort out it's engine line, with support from RLM (both with resources and with technolgy transfer from Jumo - lubrication - and BMW - valves), before we try and push the engines.

Having enough C3 fuel at least will give an overall boost in performance and power compared to what the US /UK was capable of, they were running most of their engines later in the war at +18, 21 even 25psi and whatever the US equivalents are which i understand is equivalent to 2,2 to 2,7 ata ( still have not come to grips to psi, ata and inch Hg conversions), while most boosted german engines were running about 1,8 ata, with very few cleared for 2 ata.

Is the displacement of the engines and quality/capability of superchargers accounted anywhere?

 

[Nell_Lucifer]

Imo if there was any room for a Me-163 aircaft would have been something like the Lippisch P15 or P20 configurations, with one 003 or 004 jet engine, complementing the Me-262 in a sort of high low mix, and displacing the He-162. Though while the 163 airframe had very good flight characteristics, i don't know if they will be largely retained if a jet engine is fitted, there will be a bulkier fuselage and increased weight i think.

Well I was thinking more early war (1940-1942) hence the HeS 3b or 6 engines as they would be available much earlier than any 003 or 004 ones. (Though the HeS 30 would be a much better fit and simply a better choice but I am uncertain if it could be put into production by 1942)

The weight of the HeS 3b is 360 Kg, ~double the Walter's engine weight so not that great of a weight increase compared to say the Jumo 004 at ~800 or so kilograms. But yes, for any future fighter, the P.15 would be the best choice, better visibility, landing gear.

 

[tomo pauk]

Imo if there was any room for a Me-163 aircaft would have been something like the Lippisch P15 or P20 configurations, with one 003 or 004 jet engine, complementing the Me-262 in a sort of high low mix, and displacing the He-162. Though while the 163 airframe had very good flight characteristics, i don't know if they will be largely retained if a jet engine is fitted, there will be a bulkier fuselage and increased weight i think.

I'm always the fan of the idea that Me 163 is designed around a jet engine

The weight of the HeS 3b is 360 Kg, ~double the Walter's engine weight so not that great of a weight increase compared to say the Jumo 004 at ~800 or so kilograms. But yes, for any future fighter, the P.15 would be the best choice, better visibility, landing gear.

Me 163 carried about 2 tons of fuel+oxidizer. As a jet-propelled A/C, it can carry 1000 kg of fuel and still be both rangy and light.
(He 162 carried 675 kg of fuel in fuselage and wing).

 

[oldironside]

I'm always the fan of the idea that Me 163 is designed around a jet engine

Me 163 carried about 2 tons of fuel+oxidizer. As a jet-propelled A/C, it can carry 1000 kg of fuel and still be both rangy and light.
(He 162 carried 675 kg of fuel in fuselage and wing).

Maybe something closer to the Me 263, which was slightly larger and had a permanent undercarriage rather than the dolly the 163 used.

 

[ric350]

I think these cover the various performance/power differences pretty well:

ric350

 

[tomo pauk]

Maybe something closer to the Me 263, which was slightly larger and had a permanent undercarriage rather than the dolly the 163 used.

Germans needed to manufacture a great number of jet-propelled fighters to replace the under-performing piston-engined fighters against the WAllies. 1-engined jet fighter is a more realistic venue towards that than the Me 262 (or He 280, for that matter).

So yes, be it the 263, or P.15, or P-20, or an in-time He 162 with proper wings, or B&V P.211 - I'm okay with either.

 

[mack8]

Germans having enough of the C3 for all of their fighters will require some nasty handwaving

BMW 801D was running on C3 fuel from the get go. It was still restricted both in rpm and boost until the improved spark plugh were found for it, and until BMW came out with chrome-plated valves, etc. See here.
Hopefully DB can sort out it's engine line, with support from RLM (both with resources and with technolgy transfer from Jumo - lubrication - and BMW - valves), before we try and push the engines.



Is the displacement of the engines and quality/capability of superchargers accounted anywhere?

I know may sound like a neophite, but just to clarify, even if DB-601E and 605A were running on C3, they will still be initially limited to 1200PS/1,3ata and 1310PS/1,3 ata respectively? Running on C3 wouldn't alleviate at least in part their reliability issues which forced them to reduce power ratings, or provide more power for the same ata/rpm specs? I'm not sure if i'm asking the right questions, hopefully you know what i'm trying to get at

 

[tomo pauk]

I know may sound like a neophite, but just to clarify, even if DB-601E and 605A were running on C3, they will still be initially limited to 1200PS/1,3ata and 1310PS/1,3 ata respectively? Running on C3 wouldn't alleviate at least in part their reliability issues which forced them to reduce power ratings, or provide more power for the same ata/rpm specs? I'm not sure if i'm asking the right questions, hopefully you know what i'm trying to get at

I get the point of your questions: higher-octane fuel = greater boost = greater power at low altitudes.
Still - the engines were with a flawed lube system (DB is guilty part here) and valves (RLM is guilty part here). Running at higher boost to produce more power induces the additional stress on the engine, where again the weakest links will give in, and with them the whole engine.
War-time Merlins and V-1710s were with good lubrication and with properly coated valves, meaning they have had easier time to withstand the much increased stress.