Luftwaffe pressing more & earlier towards water-alcohol injection (ADI) than towards high-octane fuel?

[tomo pauk]

Perhaps start out by trying to 'militarize' the M-W system as used on the 'rekord' DB 601 engines that powered the He 100?
Shortcoming of the ADI is mainly in that it requires another tank to be filled, and that joint consumption of fuel + ADI mixture is greater than that of just high-octane fuel for the same or similar boost levels.
Benefit of the ADI is the internal cooling effect (might help out with the nickel-starved conditions that Germans had during ww2), manufacture of methanol should probably be easier than the manufacture of fuel, and especially of the high-octane fuel. On same boost, seems like lower-octane fuel + ADI was making a tad better power. Effects of ADI were still notable at the rated altitude of an engine, while the effects of the high-oct fuel were present pretty much at lower altitudes.

Japanese were experimenting with the ADI on the modified DB 601Aa engine, that, together with higher redline (2700 rpm) was making 1550 PS for short time.

As noted in the title, the production of the high-octane fuel is to be very much curtailed in return. The 1st engines with MW and B4 fuel - call it 'DB 601N+' entering the service by late 1940.

 

[Shortround6]

In Heron's book "development of Aviation fuels" referred to earlier there are about 5 pages on water injection or water/alcohol. it is rather general and again is mostly concerned with US development. Since P & W used it the most it concentrates on P & W.
The Canadians did some work because in the early part of the war they could not get enough 87 octane fuel. They had supply caches of 80 octane fuel in the northern wilderness and the ability to use 80 octane + water injection instead of 87 octane was important. Heron does not say how it worked out.

It is a shame that Heron's book is so hard to get.

It seems to be available on Amazonas a kindle edition for $8.95 combined with "Development of Aircraft Engines".
There were no pictures, or charts/graphs in the original printed book.

 

[tomo pauk]

It seems to be available on Amazonas a kindle edition for $8.95 combined with "Development of Aircraft Engines".
There were no pictures, or charts/graphs in the original printed book.

Hathi trust has these books here.

 

[mack8]

Perhaps start out by trying to 'militarize' the M-W system as used on the 'rekord' DB 601 engines that powered the He 100?
Shortcoming of the ADI is mainly in that it requires another tank to be filled, and that joint consumption of fuel + ADI mixture is greater than that of just high-octane fuel for the same or similar boost levels.
Benefit of the ADI is the internal cooling effect (might help out with the nickel-starved conditions that Germans had during ww2), manufacture of methanol should probably be easier than the manufacture of fuel, and especially of the high-octane fuel. On same boost, seems like lower-octane fuel + ADI was making a tad better power. Effects of ADI were still notable at the rated altitude of an engine, while the effects of the high-oct fuel were present pretty much at lower altitudes.

Japanese were experimenting with the ADI on the modified DB 601Aa engine, that, together with higher redline (2700 rpm) was making 1550 PS for short time.

As noted in the title, the production of the high-octane fuel is to be very much curtailed in return. The 1st engines with MW and B4 fuel - call it 'DB 601N+' entering the service by late 1940.

Right so we have DB-601N and BMW-801C/D running on B4+MW-50? Presumably the initial power levels would be more or less similar to the OTL 601N and 801D? This possibly MIGHT help the 601N by not having the C3 fuel pass into the oil hence wrecking the engine and also not dissolving the fuel tank lining, though not sure how the 601N and 801C/D would cope with the ADI injection. One positive is that the MW tank could also be used for more fuel in situations where maximum performance is not required, so a bit more range can be had without the draggy drop tank.

Curtailing the C3 production means more B4 fuel for the same resource expenditure, so more fuel available overall. However this might mean a bit less power for late war engines, with B4 and MW-50 the DB-605 probably won't get past 1800PS while late BMW-801 models 1900-2000PS at most. Jumo-213 and DB-603 likely won't get past 2000PS with MW boost as well.

 

[tomo pauk]

Right so we have DB-601N and BMW-801C/D running on B4+MW-50? Presumably the initial power levels would be more or less similar to the OTL 601N and 801D? This possibly MIGHT help the 601N by not having the C3 fuel pass into the oil hence wrecking the engine and also not dissolving the fuel tank lining, though not sure how the 601N and 801C/D would cope with the ADI injection. One positive is that the MW tank could also be used for more fuel in situations where maximum performance is not required, so a bit more range can be had without the draggy drop tank.

Curtailing the C3 production means more B4 fuel for the same resource expenditure, so more fuel available overall. However this might mean a bit less power for late war engines, with B4 and MW-50 the DB-605 probably won't get past 1800PS while late BMW-801 models 1900-2000PS at most. Jumo-213 and DB-603 likely won't get past 2000PS with MW boost as well.

The tl;dr seems to be a net gain for the Luftwaffe?

 

[mack8]

The tl;dr seems to be a net gain for the Luftwaffe?

On balance it seems so. Perhaps the biggest gain is more fuel for operations and crucial training. Other side-effect might be for instance as the BMW-801 apparently didn't take too well to MW injection (though that being the only game in town they have to somehow make it work with just enough acceptable reliability), it might trigger earlier introduction of the DB-603 and Jumo-213 on the FW-190, say spring/summer 1943 for DB-603 and early/spring 1944 for Jumo-213. So FW-190C in 1943 and FW-190D at least 6 months early. Meanwhile the BMW-801 on B4 with or without MW would have to do it for the bombers powered by the new inlines OTL (Do-217, Ju-188 etc.)

 

[tomo pauk]

Other side-effect might be for instance as the BMW-801 apparently didn't take too well to MW injection (though that being the only game in town they have to somehow make it work with just enough acceptable reliability),

The 801D didn't like it for the purposes of overboosting at ~1.60 ata?
If that engine uses B4 + MW 50 to go to just 1.45-1.50 ata (since just on B4 it will probably not go beyond 1.30), that combo might've worked. There is also a thing of 801C on B4 + MW 50, with a tad of extra boost, perhaps 1.60 ata, due to the lower CR of the 801C?

it might trigger earlier introduction of the DB-603 and Jumo-213 on the FW-190, say spring/summer 1943 for DB-603 and early/spring 1944 for Jumo-213. So FW-190C in 1943 and FW-190D at least 6 months early.

Yes, the Fw 190 was deserving of a big V12 ASAP. Even if the DB 603A needs to be restricted in the same vogue that the DB 605A was, that still leaves it with about 70 HP more than the historical BMW 801D of 1943 at 5.7 km, less drag (almost 10% less?), tad better exhaust thrust, and a better ram air intake. Shortcoming - weight is going to be up.
DB 603A was also with a better fuel mileage at higher power settings - 465L for 1510 PS at 5.7 km (30 min setting; the 5 min setting used 535 L/h for 1620 PS); 801D used about 600 l/h (~450 kg/h) for 1440 PS at 5.7 km (3 min setting). Perhaps the radial used surplus of fuel to keep itself cool enough at the more aggressive settings, a thing that other radials also used at the time?
At cruising settings the mileage was in the ballpark.

 

[Shortround6]

Perhaps the radial used surplus of fuel to keep itself cool enough at the more aggressive settings, a thing that other radials also used at the time?

All of the Allied highpower engines were using fuel as a coolant once they had shifted to rich settings. Yes the Air cooled engines used even more fuel per HP.
A possible problem for the German fuel injected engines was the limited range of the fuel injection pumps? The amount of fuel delivered per pump stroke.

It was easier to arrange for carbs (and injection carbs) to flow more fuel per minute or per lb/kg of air.

I am not saying it could not be done, but you may need a new pump assembly.

People were somewhat leery of the long term effects of using water injection. Water was going to get into the oil. There might be possible corrosion.
Turned out that just about (or all) of the water that got into the oil evaporated back out given a long enough run time after using water injection.
There was also a problem with using fuel as a coolant in that the really rich mixtures (which did not burn anywhere near completely) washed some of the oil (or diluted it) off the cylinder walls leading to increased wear. Which one was least bad
Some spark plugs may have tolerated water injection better than others? or just didn't like the higher boost pressures?

 

[tomo pauk]

All of the Allied highpower engines were using fuel as a coolant once they had shifted to rich settings. Yes the Air cooled engines used even more fuel per HP.
A possible problem for the German fuel injected engines was the limited range of the fuel injection pumps? The amount of fuel delivered per pump stroke.

It was easier to arrange for carbs (and injection carbs) to flow more fuel per minute or per lb/kg of air.

Looking at some big radials, the R-2600-13 consumed up to 200 US gals/hr in high gear, or 770-780 L/hr, for no HP advantage over the BMW 801 - seems like fuel injection still holds the advantage.

 

[Shortround6]

Looking at some big radials, the R-2600-13 consumed up to 200 US gals/hr in high gear, or 770-780 L/hr, for no HP advantage over the BMW 801 - seems like fuel injection still holds the advantage.

It does in many ways.
The R-2600 was not exactly an innovative engine. It had cooling problems with the A and B series engines. The C's also had problems at times but they were making 1900hp.
But we are melting together basic engine size, RPM, supercharger design, fuel type, and carb vs fuel injection and other things.
The 1700hp R-2600 in the B-25s (and TBFs) was designed for 100/100 fuel. They operated it on 100/130 but they didn't increase the power. And yes, at the higher power levels it used a lot of fuel. It also operated at about the same manifold pressure as the BMW 801. 42-44in is not very different from the BMW.
Some of the Fw 190s had system were they could inject (dump?) raw fuel into the air intakes and get around 140hp extra and use 8.8lbs of boost instead of 5.5lbs. (figures from Janes so they converted to British measure). Now why did they resort to a system like that? Maybe because the standard injection pump could not flow the required amount of fuel? Maybe because the fuel being sprayed into the inlet duct/s in front of the supercharger impeller cooled the intake charge somewhat?
The P&W R-2800 was a notorious fuel hog at high power. 290 US gallons for 2000hp is a specific fuel consumption of .87lb/hp/hr. Even at a 1675hp Max cruise, the engine was using .788 lb/hp/hr. One might say that the R-2800 was not air cooled but fuel cooled
at lower power settings the R-2800 could run as low as .44-.47lb/hp/hr.

I will also note that the R-2800 was designed for the American 100/100 octane fuel. That means the cylinder fins and head fins were designed for a certain power level. For air cooled engines it was very hard to just boost manifold pressure with better fuel and get more power. The engines were limited by cooling in a very short time, well under 5 minutes.

 

[tomo pauk]

Some of the Fw 190s had system were they could inject (dump?) raw fuel into the air intakes and get around 140hp extra and use 8.8lbs of boost instead of 5.5lbs. (figures from Janes so they converted to British measure). Now why did they resort to a system like that? Maybe because the standard injection pump could not flow the required amount of fuel? Maybe because the fuel being sprayed into the inlet duct/s in front of the supercharger impeller cooled the intake charge somewhat?

The additional fuel injection in the supercharger was one way to get more boost for the better power. Excess fuel acting as ADI?
Another way was to 'simply' over-boost by keeping the throttle body opened under the rated altitude, like it was done on the Merlin III (IOW more than +6.25 psi) and similar. Fuel consumption rose to 550 kg/h (720-730 L/h), for extra 150 PS in the second gear, or more than 200 PS at S/L, basically mimicking what the C series R-2600 did at low gear, and making about 200 HP more between ~8000 and 15000 ft.
Price for the extra boost and power was the higher cylinder head temperature, and certainly the increased wear and tear.
Seems like the standard fuel pump was up to the task.

 

[AerialTorpedoDude69]

Aichi had successfully introduced ADI in the 1,400-1,500 HP range with their Atsuta engine series, which was based on the 601E. Ignoring the US technical evaluation of the engine, it was regarded as being one of their more reliable engines due to Aichi's use of superior alloying processes.

 

[tomo pauk]

Aichi had successfully introduced ADI in the 1,400-1,500 HP range with their Atsuta engine series, which was based on the 601E. Ignoring the US technical evaluation of the engine, it was regarded as being one of their more reliable engines due to Aichi's use of superior alloying processes.

That is very interesting.
Is there a good read about both the 1400-1500 HP on the Atstuta, as well as on the US evaluation of that engine?

 

[AerialTorpedoDude69]

That is very interesting.
Is there a good read about both the 1400-1500 HP on the Atstuta, as well as on the US evaluation of that engine?

Ki-61/100 Hien Performance

3 small spars might be both stronger and lighter than 2 big spars. Remember that the skin handles some of the load/spreads it out. It is going to cost more to make however. auxiliary spars are sometimes just places to hang the flaps and/or ailerons. they sometimes to not transfer torsional...

ww2aircraft.net

The sources are included in those posts (I made several in that thread), most of which are to Japanese Wikipedia for the Atsuta 32, Ha-140, and more.

As far as I'm aware, the Kawasaki Ha-140 also had ADI but it was a terrible engine. On wikipedia it's mentioned that the US's Air Service Technical command (ATSC) rated the Ha-40 as being superior to the Atsuta in construction quality and both were regarded as being far inferior to engines made by Mitsubishi and Nakajima. However, there is no source listed for this claim. Japanese Wikipedia clearly states that the Atsuta was an excellent engine. The reason Aichi couldn't make more is because their manufacturing (especially alloying) processes (designed to get around the Japanese lack of nickel and other alloying metals) were extremely labor intensive and slow.

My guess is that ATSC got their hands on a lemon Atsuta which had been beat up already.

 

[Art Medcalf]

IIRC, BMW was involved pretty early on methanol/water injection and it's application was on DB and Jumo engines in addition to the 801. I read the report several years ago and that means the copy is here somewhere. However, finding it may be difficult, I moved several years ago, and much of my stuff is in the barn. The title was "BMW sells the MW50 Process to the G.A.F. Report No. 36" an intelligence report by Party 'B', NO.1 Field Intelligence Unit dated 6.6.45 and was located at the USAF HRA.

Artie Bob

 

[Luft.4]

One should keep in mind that the 601N could not efficiently combust the C3 fuel because the fuel did not fully evaporate. Additional cooling could further worsen the problem. DB 601N + C3 + MW does not appear to be a good combination.
C3 worked in the BMW 801D because this air-cooled engine had worse cooling, allowing for the C3 to fully evaporate in the combustion chamber. Switching the BMW 801D to B4 would probably have only resulted in lower performance. Moreover, rather than using MW-50, they simply injected more C3 into the 801D as described in change instruction Nr. 104.
The Interrogation of Dipl. Ing. Norman Willich found that the power-boosting system of using additional fuel injection was decided over adding an MW-50 system because it was not only more convenient, it did not require a special tank for the MW-50.

The cover of the above mentioned report from TNA, London in which tests were conducted with a Bf 109 F4:

 

[tomo pauk]

As far as I'm aware, the Kawasaki Ha-140 also had ADI but it was a terrible engine. On wikipedia it's mentioned that the US's Air Service Technical command (ATSC) rated the Ha-40 as being superior to the Atsuta in construction quality and both were regarded as being far inferior to engines made by Mitsubishi and Nakajima. However, there is no source listed for this claim. Japanese Wikipedia clearly states that the Atsuta was an excellent engine. The reason Aichi couldn't make more is because their manufacturing (especially alloying) processes (designed to get around the Japanese lack of nickel and other alloying metals) were extremely labor intensive and slow.

Thank you.
It seems to me that Japanese V12s are even less ... understood engines than it was the case with Homare.
BTW - where the nickel was used on these engines beyond the exhaust valves?

One should keep in mind that the 601N could not efficiently combust the C3 fuel because the fuel did not fully evaporate. Additional cooling could further worsen the problem. DB 601N + C3 + MW does not appear to be a good combination.

Please note that per this thread the 601N does not have the C3 fuel - it's best bet is B4 + MW.
There are also many DB 601A and 601E engines that would've been tested/used with the MW. The DB 601A operation at 2600 rpm + MW might've been interesting.

C3 worked in the BMW 801D because this air-cooled engine had worse cooling, allowing for the C3 to fully evaporate in the combustion chamber. Switching the BMW 801D to B4 would probably have only resulted in lower performance. Moreover, rather than using MW-50, they simply injected more C3 into the 801D as described in change instruction Nr. 104.

Just using the B4 on the 801D will certainly mean lower boost = lower power. Hence the MW 50.
The simple additional injection of fuel sounds good if one has a surplus of fuel, and that was not thing that Germans were good at.

The Interrogation of Dipl. Ing. Norman Willich found that the power-boosting system of using additional fuel injection was decided over adding an MW-50 system because it was not only more convenient, it did not require a special tank for the MW-50.

That is very interesting.
In the internets, once can usually read that BMW 801D didn't like the MW 50 with C3 'main' fuel, and that was a reason for not implementing that system on the 801s.

 

[AerialTorpedoDude69]

Thank you.
It seems to me that Japanese V12s are even less ... understood engines than it was the case with Homare.
BTW - where the nickel was used on these engines beyond the exhaust valves?

The complete list of alloying metals is listed on the Japaneses Wikipedia page (do you use a baked-in translator app, like Microsoft Translate, etc...?) for the Atsuta 32. The component listed is the "crankshaft" which originally used Nickel-Manganese-Chrome steel but then switched to Silicon-Manganese-Chrome steel in the 32 model which used "double-quenching" as a hardening process. I have to to believe that the bearings also originally had nickel in them as well in order to increase service life but there's no mention of this.

It was also mentioned that the main maintenance issue was the lack of ground crews' familiarity with in-line engines. More to the point, this means that their mechanics were not properly trained. The same is true for the lack of reliability of the Homare. The mechanics hadn't been trained to work on the Homare.

Going off what's available on Japanese Wikipedia, particularly the information from a chief mechanic, Kariya, the main issue with the Homare was that the fuel injector nozzles were defective. Once the mechanic had ironed out some of those early issues (there were a few more), the engine ran fine, as you would expect with any other well-designed engine (which was what the Middleton TAIC's report suggested).

 

[Luft.4]

As the DB 601N was a high compression engine, it required a fuel which could withstand knocking better: C3 was therefore used not B4. (side note, it was built to run on C2, but when that ran out they used C3).
As the BMW 801D was a higher compression engine compared to the 801C, it required C3 fuel as well.

One theoretical solution to extend the life of the 801D could be to suggest implementing change instruction Nr. 104 sooner than late 1943, or better yet implementing change instruction Nr. 133 sooner which did away with an additional injection, opting simply for boost overriding aka erhöhten Notleistung

MW, along with nitrogen, were products made at the synthetic oil plants therefore production levels of these components would be roughly relative to fuel products as well. Lower fuel output (no matter if B4 or C3, A2 etc.), lower MW out put. This is evidenced by the fact that in late war when many aircraft had MW systems (or should have!) pilots were flying with pure water in the MW tanks! This forced them to stay below certain altitude unless they wanted the water to freeze up.

 

[tomo pauk]

As the DB 601N was a high compression engine, it required a fuel which could withstand knocking better: C3 was therefore used not B4. (side note, it was built to run on C2, but when that ran out they used C3).
As the BMW 801D was a higher compression engine compared to the 801C, it required C3 fuel as well.

With '100 oktan' fuel being as good as unavailable, both these engines will probably have somewhat lower CR.

MW, along with nitrogen, were products made at the synthetic oil plants therefore production levels of these components would be roughly relative to fuel products as well. Lower fuel output (no matter if B4 or C3, A2 etc.), lower MW out put. This is evidenced by the fact that in late war when many aircraft had MW systems (or should have!) pilots were flying with pure water in the MW tanks! This forced them to stay below certain altitude unless they wanted the water to freeze up.

Germans were also making an effort with the EW-50 (ethanol-water) come late 1944.
I'm not sure that an effort to make a liter of C3 was the same as an effort to make B4.