Ju88 and He111 potential with a 1942 Jumo 213

[wiking85]

Based on the recent threads about the Jumo 213, what would the potential of the Ju88 and He111 have been with a mass produced 1750hp Jumo 213A cleared for production in March 1942 (12 months early)? Historically there was the Ju88S and G by 1944, while there was a He111H22-3 by the same time. Could there have been both of these types in service by the end of 1942 and would it have made any difference? The Ju88S achieved top speeds of 387 mph with boost and by deleting the ventral gondola, some armor, streamlining the nose, and deleting the external bomb racks. The G series did much the same thing. The He111H22-3 got a powered turret, a range boost (1800+ miles a 400 mile increase), and a speed boost (cruise speed of 230mph, up from 180mph cruise with the He111H6 version, and a 293mph max speed). What about the standard models though? Would the Ju88A4 have gotten as big a boost? How about the Ju88C, which was the standard night fighter version of the Ju88 in 1942-43. They had much more drag. Would we have seen an earlier Ju188 in numbers or a 388 even?

This period of 1942 is prior to the serious bombing of Jumo production in 1943, so it could be phased in much more quickly than it was historically. There is also the potential that the Ostmark facility could be used for the 213, so we could see substantial numbers of this engine in production by Autumn 1942 if cleared in March 1942 for production.

 

[davebender]

Just look at historical Ju-88G.

Range/payload and cruising speed are significantly improved with the more powerful engines. You've also got enough power to stretch the fuselage (i.e. Ju-88H) for purpose of increasing fuel capacity. The additional aircraft weight might place restrictions on aircraft dive angle but that is offset by introduction of improved bomb site during 1941 to 1942.

 

[GregP]

The Heinkel He-111 is a good example. Basically you can think of it as a DC-3. That is what I was told by the Arizona CAF wing about their CASA version … flies like a DC-3 except if one engine fails, the other will get you around the pattern ONCE before overheating, make the approach a good one.

Let's take the He-111 H-6 as an example. Max speed was 273 mph … I'll get to cruise speed later. It has two Jumo 211's rated at 1,300 (F-1) or 1,340 HP (F-2) each. I'll assume we re-engine and get 1,750 HP each. Sp we go from 2,600 – 2,680 HP to 3,500 HP.

Using standard aerodynamic calculation, and assuming a 5% increase in drag for the new radiators (reasonable if not exact), I predict a new top speed of 293 mph, an increase of 7.5%. If I then assume a similar increase in cruise speed, I'd predict a cruise of 247 mph.

That's not bad, but is it a game changer? I would not care to predict the possible change in payload, but the bomb bay was limiting. I think it would have been better, but basically would have made little real-world difference. Your thoughts may open up another approach to something.

The Junkers Ju 88 A-4 had two Jumo 211 J's at 1,400 HP each (not ps). The aircraft had a 317 mph top speed. Again with standard calculation, assume 3,500 HP and … say … an 8% drag reduction (we could argue the drag reduction percent, but the delta is small). The predicted new top speed would be 351.1 mph. This is an increase of 10.7% in top speed and would probably generate a similar increase in cruise.

Is that a game changer? Your call.

The Ju 88 was already fast to our fighters of the time, but was not uncatchable at 317 mph. Take it to 351 mph and it gets closer to Mosquito territory … but planes rarely operate at top speed for long periods. It would definitely make it harder to intercept, but it's anyone's guess what the consequences might be. I suppose it would depend on the number available and the use to which they were put. Might make formidable might intruders.

Good luck with the speculation!

 

[DonL]

@ GregP

I do agree with your post, but to one issue I disagree.
The Jumo 213 was samler then the Jumo 211, he was heavier (80-100kg)but smaler, so I don't understand from where should come the + 5% drag?
I don't think that the engine gondulas of the Jumo 213 were bigger then the 211 gondulas.

http://upload.wikimedia.org/wikiped...101I-402-0270-05A,_Flugzeug_Junkers_Ju_88.jpg
A4 with 211 gondulas.

http://static3.wikia.nocookie.net/__cb20130408045960/world-war-2/images/d/db/Ju_88_G-6.jpg

G6 with 213 gondulas

 

[GregP]

Hi DonL,

You could be right. I decided that several hundred more horsepower would require a bigger radiator witrh more drag, and radiators usually cause WAY more drag than engine cowlings. But rerunning the numbers is easy.

The classic fomulas need the top speed on the existing HP and the new HP and percent change in drag. You then calculate a "k" from the speed and original HP.

I decided that 300 more HP above a 1,300 HP engine would generate something like 5% more drag, and that would be offset by the deletion of things like the gondola, the external bomb racks, and nose streamlining to give slightly more drag reduction than the slightly bigger radiators would add. The gondola and the bomb racks add a LOT of drag. I could easily believe anywhere from almost zero net drag change to 5 - 8% drag reduction with a serious cleanup in mind, but estimates are in the eye of the beholder.

What would your assumption be for the net drag change? +5% means 5% more drag and -5% means a 5% drag decrease. Whaddya' think?

My guess is adding a few hundred HP per side would make it faster by SOME amount ... the real-world gains with so little HP increase are slight, but MAY be significant in some operational missions.

 

[wiking85]

The Heinkel He-111 is a good example. Basically you can think of it as a DC-3. That is what I was told by the Arizona CAF wing about their CASA version … flies like a DC-3 except if one engine fails, the other will get you around the pattern ONCE before overheating, make the approach a good one.

Let's take the He-111 H-6 as an example. Max speed was 273 mph … I'll get to cruise speed later. It has two Jumo 211's rated at 1,300 (F-1) or 1,340 HP (F-2) each. I'll assume we re-engine and get 1,750 HP each. Sp we go from 2,600 – 2,680 HP to 3,500 HP.

Using standard aerodynamic calculation, and assuming a 5% increase in drag for the new radiators (reasonable if not exact), I predict a new top speed of 293 mph, an increase of 7.5%. If I then assume a similar increase in cruise speed, I'd predict a cruise of 247 mph.

That's not bad, but is it a game changer? I would not care to predict the possible change in payload, but the bomb bay was limiting. I think it would have been better, but basically would have made little real-world difference. Your thoughts may open up another approach to something.

The Junkers Ju 88 A-4 had two Jumo 211 J's at 1,400 HP each (not ps). The aircraft had a 317 mph top speed. Again with standard calculation, assume 3,500 HP and … say … an 8% drag reduction (we could argue the drag reduction percent, but the delta is small). The predicted new top speed would be 351.1 mph. This is an increase of 10.7% in top speed and would probably generate a similar increase in cruise.

Is that a game changer? Your call.

The Ju 88 was already fast to our fighters of the time, but was not uncatchable at 317 mph. Take it to 351 mph and it gets closer to Mosquito territory … but planes rarely operate at top speed for long periods. It would definitely make it harder to intercept, but it's anyone's guess what the consequences might be. I suppose it would depend on the number available and the use to which they were put. Might make formidable might intruders.

Good luck with the speculation!

I recall reading on these forums that the Jumo engines had the benefit of being able to operate at near maximum rpm for 30 min, is this true?

 

[GregP]

No clue ... haven't seen or heard one run ...

 

[tomo pauk]

I recall reading on these forums that the Jumo engines had the benefit of being able to operate at near maximum rpm for 30 min, is this true?

That was true for many engines. Most of the German engines have had 'Steig Kampfleistung' limited to 30 minutes, and in most of German engines that was the second most powerful engine setting.
The Jumo 213E (in Ta-152) was allowed to run in 'Notleistung' power setting for 30 min - that was on the highest RPM, and, in case water injection was not installed, highest boost (= max power).

 

[wiking85]

The Heinkel He-111 is a good example. Basically you can think of it as a DC-3. That is what I was told by the Arizona CAF wing about their CASA version … flies like a DC-3 except if one engine fails, the other will get you around the pattern ONCE before overheating, make the approach a good one.

Let's take the He-111 H-6 as an example. Max speed was 273 mph … I'll get to cruise speed later. It has two Jumo 211's rated at 1,300 (F-1) or 1,340 HP (F-2) each. I'll assume we re-engine and get 1,750 HP each. Sp we go from 2,600 – 2,680 HP to 3,500 HP.

Using standard aerodynamic calculation, and assuming a 5% increase in drag for the new radiators (reasonable if not exact), I predict a new top speed of 293 mph, an increase of 7.5%. If I then assume a similar increase in cruise speed, I'd predict a cruise of 247 mph.

Good calculation for top speed, that was the exactly the top speed of the Jumo 213 equipped He111. The cruise speed was 230mph. It also upgraded the range to over 1800 miles, and increase of 400 over the 211.

That's not bad, but is it a game changer? I would not care to predict the possible change in payload, but the bomb bay was limiting. I think it would have been better, but basically would have made little real-world difference. Your thoughts may open up another approach to something.

IIRC its had a 3000kg payload. For the Eastern Front the above upgrade in performance would be helpful for sure. I don't see a downside, but 'game changer' would need to be defined. I suppose allowing for Operation Eisenhammer would be a game changer. Otherwise anything that reduced losses would only help create a positive feedback loop in terms of reducing combat losses and keeping more experienced crews alive longer.

The Junkers Ju 88 A-4 had two Jumo 211 J's at 1,400 HP each (not ps). The aircraft had a 317 mph top speed. Again with standard calculation, assume 3,500 HP and … say … an 8% drag reduction (we could argue the drag reduction percent, but the delta is small). The predicted new top speed would be 351.1 mph. This is an increase of 10.7% in top speed and would probably generate a similar increase in cruise.

Is that a game changer? Your call.

The Ju 88 was already fast to our fighters of the time, but was not uncatchable at 317 mph. Take it to 351 mph and it gets closer to Mosquito territory … but planes rarely operate at top speed for long periods. It would definitely make it harder to intercept, but it's anyone's guess what the consequences might be. I suppose it would depend on the number available and the use to which they were put. Might make formidable might intruders.

Good luck with the speculation!

Any idea what the cruise speed would be? That would be the important point IMHO. It would seriously help survivability for the the crews, so positive feedback loop as per above. I think the Ju388 would be more in the category of game changer due to its altitude capabilities, which makes interception harder. Having the engine to make use of the airframe sooner would probably go a long way to making sure it enters service in 1943, assuming there is no Ju288 project. Being a refinement of the Ju188, which would also start sooner without the Ju288, I could see that happening sooner too. That's much more a game changer than the other options that were historically never available.

 

[Shortround6]

Improvement may be a bit better because the powers given are for take off and not power at altitude. The 213A also had a FTH (in high gear) about 4000ft higher than various 211 models.

The He 111 is never going to be turned into a fast bomber but several hundred more HP at take-off might do a fair amount for it's load lifting capability. Once bombs/fuel are gone it may help getting back to base on one engine and while an extra couple of hundred HP is no guarantee for multiple "go rounds" it sure can't hurt. Extra power may cut down on the need for rocket assistance for heavy take-offs from short strips.
Another thing is wither the Jumo 213 is used as a straight "plug in" on the He 111 or wither the He 111 gets sort of a Ju-88/188 'make-over'. Do they actually change anything to take advantage of the extra power? Beef up landing gear, add wing area, increase defensive armament, etc.

Same with Ju-88. Not only more power but power higher up. Make it more Mosquito like?

 

[Shortround6]

Copy of a chart provided by Krieghund in another thread.

He 111s with the Jumo 211F engine seem to be limited to 14000kg max take off weight. An extra 750kg of fuel would certainly add to the range when carrying a heavy bomb load. With a pair of even 1500 hp engines the He 111 would have power loading at 15670kg close to what it had at 14000kg with a pair of 1340hp engines. Granted the wing loading would be higher.