1941: the best V-12 engine

[Shortround6]

Those are the headline acts, to be sure, but you've got a couple of other acts at this festival as well. From Russia there is the AM-35 and the M-105P (a much reworked and enlarged H-S 12Y rated up to 2700 rpm and a very solid 1200-1250 hp), you've also got the wonderful Italian Isotta Fraschini Delta, a 27 liter air cooled V12 capable of around 700-800 hp.

The other acts are distinctly second string. When they come on stage it is time to hit the restroom and then go for more refreshments because you won't miss a thing.
The AM-35 was a beast of an engine that went 240-500lbs more than the 4 prime engines. It also had a very short service life, 50 hours between overhauls?
The M-105P while light in weight is also down on power,, it doesn't hit that "very solid 1200-1250 hp" until mid 1942 and does it at rather low altitudes. While it goes longer between overhauls than the AM-35 it is still a short lived engine compared to the Allison and Merlin. Compared to DB and Jumos I don't know.
As for the Isotta Fraschini Delta, 750hp at 4000meters for a 510kg engine is too little. This is not a small engine either in physical size. About the only engine mentioned that it is narrower than is the AM-35.

Fastmongrel has mentioned the Ford V-12, Almost all American aircraft engines took a minimum of 3 years to go from initial design to 5th production engine. Even if Ford pulls the miracle of the century the engine wouldn't be ready until mid 1942.

 

[Shortround6]

Fuel inject a Merlin with German type fuel injection and you loose power. The British and American carburetors and/or single point injectors lowered the intake charge temperature by about 25 degrees C. Denser charge and a bit more allowable boost?

 

[Timppa]

In case you thin that a special feature of an engine should adds 'points', please post about that.

Ok, Mikulin AM-35/38. AFAIK the only aircraft engine of the era, that had dual overhead cams (DOHC). It had also variable supercharger inlet vanes, quite a rare feature, that (much later) Jumo-213 had also.

Although heavy, the AM-35 had very good altitude performance in the MiG-3, better than the Bf109F.
Power 1,350 hp (-35), 1,600 hp (-38 ).

 

[Tante Ju]

Fuel inject a Merlin with German type fuel injection and you loose power. The British and American carburetors and/or single point injectors lowered the intake charge temperature by about 25 degrees C. Denser charge and a bit more allowable boost?

So what's stops you from injecting charge cooling purpose fuel to the supercharger inlet in a DFI engine? As was done on BMW 801..?

 

[Shortround6]

Ok, Mikulin AM-35/38. AFAIK the only aircraft engine of the era, that had dual overhead cams (DOHC). It had also variable supercharger inlet vanes, quite a rare feature, that (much later) Jumo-213 had also.

Although heavy, the AM-35 had very good altitude performance in the MiG-3, better than the Bf109F.
Power 1,350 hp (-35), 1,600 hp (-38 ).

Did it NEED dual overhead cams? and if so why? It had a 160mm bore so it's valves weren't any bigger ( or much bigger) than some other engines and it didn't turn as many RPMs so the valves opened and closed fewer times per second. Used dual overhead cams because of bad valve springs?
The variable supercharger inlet vane is a good idea.
Altitude performance was good but weight for power was as high as a two stage supercharger or turbo. the -38 seems to have had even more trouble in service (what little service it saw) than the -35.

 

[Shortround6]

So what's stops you from injecting charge cooling purpose fuel to the supercharger inlet in a DFI engine? As was done on BMW 801..?

Nothing......except they are using the combustion fuel to do it and not running extra fuel through the engine that won't be burned. They also don't need a separate fuel line and metering system to do it.

 

[tomo pauk]

The DB 601E had 1350 PS emergency power at 2700 rpm and 1,42 ata and
1200 PS "fighting" power at 2500 rpm and 1,30 ata.
Official sources differ at the clearance of the emergency power (1350PS) mostly claim end of 1941.

The DB 601E with the Bf 109 F-4 had it's best outputperformance at 6200m (20341 ft) with max speed of 660 km/h (410 mph) at 1,42 ata 2700rpm
At 8000m (26246 ft) the DB 601E with the Bf 109 F-4 was still at 649 km/h (403 mph) at 1,42 ata 2700rpm

With steig und Kampfleistung normal (fighting) power at 1,30 ata and 2500 rpm/ Bf 109 F-4:

Best outputperformance at 6200m (20341 ft) with max speed of 635 km/h (395 mph)
At 8000m (26246 ft) max speed was 620 km/h (385 mph)

Source Kurfürst:
Kurfürst - Mtt. AG. Datenblatt, Me 109 G - 1. Ausführung
Kurfürst - Mtt. AG. Datenblatt, Me 109 G - 1. Ausführung

I do agree that DB-601E was an over performer, even with Notlesistung blocked.
Now, looking at this web page, the table, dated 29th Nov 1941, the Notleistung is stated as blocked for the time being ('z. Zt. gesp' - zu Zeit gesperrt'). The web site (not the table) gets it wrong, saying:

The flight tests could have also contributed to the cancellation of the limitation of the engine power to climb/combat power, since the specification for take off/emergency power had the note "at this time".

it is "at this time" ("z. Zt."), but the "gesp." part eluded the author of the web site.

This is a much much better altitude performance then the P40 with an Allison with single stage, single speed supercharger.

There is no doubt that, in 1941,the V-1710 was in a great disadvantage vs. the DB-601, since it's swept volume was a 1/4 less. The Jumo-211 also has greater swept volume, plus it features 2-speed supercharger.
The V-1710 is in a disadvantage vs. Merlin XX/45 on accounts of it's less able supercharger 'complex'.

 

[Shortround6]

Against that you have the Allison being the lightest engine of the bunch. The C series with the weird reduction gear is phasing out and the E&F series are coming in. Allison's time between overhauls may be the best of the bunch?
Not much used in 1941 but very little was needed in order to use the WEP settings later. Adjustments of linkage and stops, few if any internal parts.

 

[Shortround6]

When was the turbo P-40 built?

It may not have been. There seem to be pictures and records of plenty of other one off prototypes with different radiators and modifications but no pictures and no real records of a turbo P-40. Don Berlin may have wanted to build one, a turbo may have been delivered to the Curtiss factory but was metal ever cut for the installation?

The P-63 was significantly bigger than the P-39, but did not have a turbo. It didn't have the XP-39's air:air intercooler either, using either a liquid:air intercooler (like the Merlin's) or none (used ADI instead).

The P-63 relied on Allison's 2 stage development, which took some time.

I would also note that the graph and performance figures at WWII aircraftperformance are for a plane with about 100 gals of fuel on board and at 7705lbs no wing guns. The 37mm gun with 30 rounds of ammo and two synchronized .50cal with 200 rounds each. A test of an experimental airplane in July of 1943 is a long way from production/service 1941

 

[Denniss]

The Jumo 211F may have been rated with a similar power like the DB 601E but in the Jumo it was just a short burst for take-off while the DB could hold it for 3-5 minutes.

 

[tomo pauk]

Wasn't the 'Notleistung' an 1 minute rating for the DBs? Ditto for the Jumos? The 'Steig und Kampfleistung' being 30 min rating?

Here is a chart (basis being the Jumo-211F chart, acquired at AEHS site) comparing the Merlin XX (green line, Military power, 5 min rating), DB-601E (red - 'Steig kampfleistung', brown - 'Notleistung') and, obviously, the 211F (thick black - 'St. Kampfl', blue - 'Notlesitung').
Evidently the DB-601E on 'St Kmpfl'. can rougly equal, above 4800m, the Jumo 211F that is using 'Notleistung', while beating it between between 2,2km and 4,8km. Great advantage 601E here - 30 min vs. 1 min for 211. The Merlin XX *(5 min rating) is slightly better vs. the DB-601E (still managing 25 additional minutes; advantage 601E) above 5,5km, while having significant disadvantage between, roughly, 4,3 and 5,2 km.
The DB-601E really trumps the lot when using the Notleistung, however, I remain to be convinced that such a power setting was allowed in 1941. Still, the 601E seem like the best engine in 1941, even on a lower power setting, and the ability to use the prop cannon can be it's icing on the cake.

*I've used the data from the V-1650-1 table; the WER/Combat ratings were 1300 HP on 4600 ft, and again on 12000 ft (3700m), but IIRC those were not allowed in 1941 (even for the original Merlin 20 series).

 

[Denniss]

The thin line for 211F Notleistung is only theoretical as it was indeed permitted only for one minute. The Ju 88 A-4 manual called this "Ablugleistung".
Some of the thin lines are for on-flight power with RAM effect.

The 601E Notleistung was AFAIR only permitted for 3 minutes, may have been extended to 5 minutes later.

 

[tomo pauk]

The thin line for 211F Notleistung is only theoretical as it was indeed permitted only for one minute.

The DB-601A did also had it's Notleistung limited to 1 minute duration, yet that was never discussed as being theoretical. So it seem rather practical to me, the Notlesitung for the 211F.*

The Ju 88 A-4 manual called this "Ablugleistung".

Could you be so kind to translate the term in English?

Some of the thin lines are for on-flight power with RAM effect.

Of course. I've 'augmented only the line(s) where the ram effect is not present (v=0 km/h)

The 601E Notleistung was AFAIR only permitted for 3 minutes, may have been extended to 5 minutes later.

I do have the table denoting the power settings for the 601E, but, unfortunately, it does not list the allowed time for neither of the ratings. I do not have any manual about 601E, however.

*edited to add: the Notleistung for the DB-601N was also restricted to 1 minute: http://kurfurst.org/Engine/DB60x/DB601_datasheets_N.html

 

[tomo pauk]

Jumo 211 F: 1340PS

lenght: 2172,5 mm
width: 804mm
height: 1053mm
Dry weight without intercooler 720kg

DB 601E: 1350PS

lenght: 1722mm
width: 739mm
height: 1027mm
Dry weight without intercooler 610kg

The 601E was long 2304mm with prop shaft; the length of the 211F was indeed as stated, but it includes prop shaft. Of course, neither had an intercooler (the 211 J have had one).

 

[DonL]

No Tomo this is quiet incorrect!

You show a DB 601 E with complete supercharger and prop shaft!

The Jumo lenghts was without additional equipment!

You can see this at the handbook and the link I have posted!

Look at my post 8. It is only the Jumo engine and not the engine with additional equipment!

Also the Dry weight of the DB 601 E was 610kg and of the Jumo 720 kg (Dry weight) without additional equipment!

With additional equipment the DB weight 780 kg and the Jumo near 900kg (890kg).

 

[Denniss]

211F thin lines for Notleistung were theoretical, not the initial fat line.
The 601A/Aa max power for one minute is known (not available in all a/c types), the later 601N (in Bf 109F) may have received more than the one minute claimed in this datasheet, I can't remember to have seen a just one-minute max power in the 601E.

The Jumo211 length is indeed with prop shaft, according to Jumo 211B/D manual the length without Nabe was 1765 mm. Both length and weight are for engine + supercharger but without intercooler.

 

[Shortround6]

That length seems a lot better.

Weights on the Jumo's are all over the map. I guess if you could find a set of data sheets in order it might make sense. The 211A was quite a bit lighter according to most sources but there may have been a steady growth in weight as the engine was beefed up to make more more power?
Around 1450lbs dry for the 211A?
Around 1600lbs dry for the 211B?
Not sure where the D falls?

Results of British war time test of 211D;

1943 | 1957 | Flight Archive

Article on the 211 series. Granted it is wartime but some info may be good.

1943 | 2102 | Flight Archive

 

[tomo pauk]

No Tomo this is quiet incorrect!

You show a DB 601 E with complete supercharger and prop shaft!

The Jumo lenghts was without additional equipment!

You can see this at the handbook and the link I have posted!

Look at my post 8. It is only the Jumo engine and not the engine with additional equipment!

No need to yell at me
The supercharger at German V-12s barely influences the length - it's side mounted. All the photos at the manual for 211F show prop shaft, that is shorter than the 601E's prop shaft. So no wonder that 601E counts more cm in length. The 211D is long, 'ohne Nabe' ('without prop shaft'), 1745mm, according to the manual.

Also the Dry weight of the DB 601 E was 610kg and of the Jumo 720 kg (Dry weight) without additional equipment!

With additional equipment the DB weight 780 kg and the Jumo near 900kg (890kg).

I've never disagreed with that.

211F thin lines for Notleistung were theoretical, not the initial fat line.
The 601A/Aa max power for one minute is known (not available in all a/c types), the later 601N (in Bf 109F) may have received more than the one minute claimed in this datasheet, I can't remember to have seen a just one-minute max power in the 601E.

Hmm, since the 211F was mostly a bomber aircraft, maybe the Notlesitung was not allowed for those? Only allowed when the A/C was a night fighter, like Ju-88 version(s)?
The initial fat line is 'Steig Kampfleistung', original chart is here:
http://www.enginehistory.org/German/Jumo%20211/jtf1.jpg

The Jumo211 length is indeed with prop shaft, according to Jumo 211B/D manual the length without Nabe was 1765 mm. Both length and weight are for engine + supercharger but without intercooler.

1745mm actually

 

[Denniss]

The sheet terms it "Notleistung" but in bomber aircraft manuals you'll se a more proper term "Abflugleistung" - take-off power: Short-term power for the heavily-laden bombers for take-off only.
Thats very similar for the 1-min rating of the DB 601A/Aa family - short-term power to easy take-off for heavily-laden bombers. I'm not really sure this power rating was available in the Bf 109.

 

[Shortround6]

The supercharger was always included in the dry weight and dimensions of an engine. The charge cooler ( inter or after) was not. Starters and generators were not.