Jumo-213A for Dora

[Yo-Yo]

I should have placed this materials before... but better late than never. It's a translation from the Russian part of the forum. Maybe some aspects of the engine performance will become more clear. Hope you will enjoy the esse...

 

Due to numerous requests from the workers, food prices will be increased ... Ooops, sorry... gradually we will begin to talk about the Dora and its features. As it was for the Mustang development, the story will not be just for sake of being told, but to show what depths of modeling we climb to modelling similar to the real-world aircraft.

 

Because apparently after the Mustang release, the workers would ask for its historical rival, the BMW-801 was developed in my spare time, and the new engine (take my word) would have been made from the Merlin for relatively low cost, even though Komandogerat must be developed.

Important note: “workers” and their “requests” was the lovely stamp of Soviet propaganda I hate and thus often recall.

And then quite suddenly the information fell from somewhere that the next aircraft would be the Dora… and it was not good news at all... at least for me.

As you know, the D9 used the Jumo-213A engine. And the Junkers motors had a great feature that almost led me first into a light stupor. Look at the engine performance vs altitude charts - you'll understand. (Look for yourself – there are at least two available diagrams, plus a manual, and all a bit different).

For Jumo engines, as altitude decreases below the full throttle or critical altitude, power remains constant or even increases, although for the engine with plain supercharger automatically maintaining constant boost pressure below critical altitude, its power decreases with decreasing altitude.Power drops due to excess pressure ratio of the blower below the critical altitude. The air is compressed and heated, then the excessive pressure is throttled, but the air keeps excessive temperature. There are several subseqent reasons to get less power: overheated air has less density at the same pressure (engine power is proprtional to air mass flow, i.e. density at the same volume flow that is considered constant at certain rpm), the excessive power to this overheating is stolen from the engine. There is another one disadvantage of low altitude throttling - overheated air is prone to detonation.

The ideal way to solve this problem is to have variable pressure ratio blower.

 

German engineers successfully solved the problem: for the DB-60X - between the first and second critical heights - gradually increasing the blower speed, and Junkers engineers solved the problem in general by creating a supercharger with variable pressure ratio due to special vanes at the blower inlet. Additionally, as the vane throttle could not work in full range of required power settings, the engine was equipped with a throttle of traditional type to control low power range.

To have engine performance vs altitude near perfect, thus, having no saw-teeth, the designers used the automatic adjustment not just for boost pressure, but for the air mass flow.

Hydro-mechanical MBG was an analogue of BMW Kommandogerat, provided almost the same functions, combining and defining a common coordinated program for the prop governor, boost controller, ignition timing and fuel injection pump. An interesting detail: the Germans were able to combine in the same unit with common aneroid sensor controllers for air mass flow and fuel flow, thus, simplifying the device and avoid possible mismatches in air-to-fuel ratio, as two separate aneroid controlled units would meter air and fuel separately.

MBG also automatically switched the blower speed at the certain altitude.

If oil pressure used for MBG automatics dropped, it shifted to manual mode and the auxiliary throttle began to work in full range providing MP control.

 

Emergency power

 

There are a lot of legends and myths regarding these modes. There are several reasons for it: they have never, in my opinion, been truly modeled in simulations, popular books and articles contain sometimes contradicting, sometimes not true facts, and really accurate technical information only can be found in the authentic German manuals.

The most well-known system - MW-50 that made possible to boost the supercharged engine without the risk of detonation. As the British and American engines used air cooling system (inter-and aftercooler) requiring to increase the area and mass of radiators, pipelines, having an additional pump, tank and coolant, the Germans chose a different way - the water-alcohol mixture. Of course, both ways have their advantages and disadvantages, so it’s difficult to say for sure which one was right. Probably, it was done regarding technology allowance, the opportunities to place system parts in the aircraft, etc. Moreover, regarding the features of the fuel metering, injection of 40-50% water-alcohol mixture in Merlins would simply be unprofitable waisting of alcohol. Why so - it will become clear later.

 

Even if you just inject poor water into the supercharger it increases the power, because at constant boost pressure it increases the density of the air entering the cylinders. A similar effect is achieved due to inter / aftercooler. Lowering of the temperature increases the manifold pressure detonation begins at providing an additional opportunity to further manifold pressure safe increasing.

As you probably remember, automatic injection type Bendix-Stromberg carburetor used in Merlin meters the fuel by measuring the air mass flow (venturi tube determines the volumetric flow rate, gas-filled aneroid - a function of air density, and a needle of special form in an air pass from the venturi tube works as a computer, multiplying these values). If you inject pure water, carburetor correctly determines that additional fuel is required and fuel-air ratio (alpha) is kept. Water-alcohol mixture itself contains a sufficient amount of fuel, so the rich mixture at high power rates will become richer only increasing the amount of unburned fuel in the cylinders.

The Junkers engine MBG, as MW-50 was engaged, automatically readjusted the blower controller to the increased air flow. As the additional amount of fuel supplied with MW-50 was not sufficient to maintain the desired mixture strength, MBG fuel pump for the engines allowing MW-50 was reconfigured for more fuel flow.

The blower controller switch shifting up maximal limit was made in a very simple way: methanol (sometimes ethanol!) vodka fed an injector passing from the tank under pressure of the air taken after the supercharger. This pressure moved a piston driving an oil valve that opens oil passage to the servo-piston. The servo-piston shifts maximal boost limit to the new position adjusted to get desired increased boost.

The system was sensitive not only to the fluid pressure but also to the pressure of propellant air after emptying the tank. On the one hand it required constant pilot’s attention to avoid "dry running" at emergency power boost that could ruin the engine, and on the other, it possibly could be a reason to implement reduced "dry" boost rate (1900 hp) that was considered safe.

 

Why Germans used methanol…(we will not discuss the matter what is better to drink… methanol gives the same effect but only once in somebody’s life). The real reason is that methanol has slightly higher latent heat of vaporization, so it’s better cooler, and it has higher octane number.

Edited September 19, 2013 by Yo-Yo

[NineLine]

I should have placed this materials before... but better late than never. It's a translation from the Russian part of the forum. Maybe some aspects of the engine performance will become more clear. Hope you will enjoy the esse...

 

Thanks for finally posting this on the English side, I hope my pestering wasnt too much :)

[Yo-Yo]

Thanks for finally posting this on the English side, I hope my pestering wasnt too much :)

 

Is the text now more readable than it was after Google translator? :)

[NineLine]

Is the text now more readable than it was after Google translator? :)

 

Much better :)

[NineLine]

You are right, its not really on topic, but it would be nice to see options for fuel types, but I am not sure how easy that would be to add, maybe its something they could do on the DCS WWII side...

 

 

So if the FW190 is getting MW50 then does it mean P51D will get access to 150 Octane fuel? Afaik it is not currently modelled in DCS Mustang.

 

Sorry if that's not related to FW190, just jumping on the occassion to ask that question :)

[Yo-Yo]

You are right, its not really on topic, but it would be nice to see options for fuel types, but I am not sure how easy that would be to add, maybe its something they could do on the DCS WWII side...

 

The 150 grade fuel will ruin the fine balance we can see between Dora and Mustang. Additionally we have no information what was the cost for 75 inches boost regarding engine lifetime and reliability.

 

Anyway, probably Spit Mk IX with Merlin 66 can use it. Let's see...

[NineLine]

The 150 grade fuel will ruin the fine balance we can see between Dora and Mustang. Additionally we have no information what was the cost for 75 inches boost regarding engine lifetime and reliability.

 

Anyway, probably Spit Mk IX with Merlin 66 can use it. Let's see...

 

I can understand balance, but thinking on a grander scheme of the digital battlefield, imagine having limited resources, and only having the high octane in smaller amounts. I could be an interesting dynamic. Same with Methanol and other such resources... but maybe out of the scope of what can be done right now.

[Kwiatek]

P-51 used 150 octan fuel and higher boost preasure during 1944-45 with no problems. But im afraid that in DCS P-51 with higher boost would blow its engine very quickly looking how quickly it blow engine with standart emergency power.

 

I still think that there is something not right with cooling system in DCS P-51.

 

BTW Fw 190 D-9 used also 1900 PS mod instead MW 50 instalation which also give better performacne then standart 1.65 Ata version. I think 1900 PS version would be the best choice for DCS as for standart boost P-51 competition.

 

P-51 with higher boost performacne documents:

 

http://www.wwiiaircraftperformance.org/mustang/mustangtest.html

 

Edited September 19, 2013 by Kwiatek

[Kwiatek]

Jumo 213A: ( both with MW50 and 1900 PS power curves) :

[Yo-Yo]

P-51 used 150 octan fuel and higher boost preasure during 1944-45 with no problems. But im afraid that in DCS P-51 with higher boost would blow its engine very quickly looking how quickly it blow engine with standart emergency power.

 

I still think that there is something not right with cooling system in DCS P-51.

 

BTW Fw 190 D-9 used also 1900 PS mod instead MW 50 instalation which also give better performacne then standart 1.65 Ata version. I think 1900 PS version would be the best choice for DCS as for standart boost P-51 competition.

 

P-51 with higher boost performacne documents:

 

 

If you do not stall the plane at 67 inches its cooling system works perfect... and I must say that 1.65 ata is not for 1750 hp (1.52 ata) but more close for 1900 hp mode.

Edited September 19, 2013 by Yo-Yo

[Yo-Yo]

Jumo 213A: ( both with MW50 and 1900 PS power curves) :

 

It seems to be not very similar to the original curves for 213A, especially for MW-50, though all curves below is plausible. THe point is that the model tuned for factory data gives similar results for 1900 hp

 

Sometimes this diagram considered as for experimental engine. There is no signs of tested engine type . It's very unusual for Germans as they always wrote not only the type but all significant data about the test up to factory No. of aircraft or engine tested.

Edited September 19, 2013 by Yo-Yo

[Kwiatek]

If you do not stall the plane at 67 inches its cooling system works perfect... and I must say that 1.65 ata is not for 1750 hp (1.52 ata) but more close for 1900 hp mode.

 

Yea you right 1900 Ps is for 1.7 Ata. For standart version it was 1.55 Ata.

[Kwiatek]

If you do not stall the plane at 67 inches its cooling system works perfect...

 

Hmm at high speeds it work ok but at slowier speeds at WEP or even at 61 inches temperatures rise very quickly alhough still is airflow by radiator - plane still fly at speed ab. 150-200 mph which isnt soo slow.

 

BTW

 

Do you know what was happend with force fedback stall buffeting in P-51 with 1.2.6? Casue before it work good but now it was disabled?

[Yo-Yo]

Hmm at high speeds it work ok but at slowier speeds at WEP or even at 61 inches temperatures rise very quickly alhough still is airflow by radiator - plane still fly at speed ab. 150-200 mph which isnt soo slow.

 

BTW

 

Do you know what was happend with force fedback stall buffeting in P-51 with 1.2.6? Casue before it work good but now it was disabled?

 

The cooling system successfully passed two tests: the first one was according warime Mustang tests that gave full cooling system charachteristics at the certain engine power rate at the certain speed and altitude.

 

The second test was known scoop position as Mustangs performs level flight pre-airshow patterns and then - standard airshow pilotage. Both at 46" /2700.

[Yo-Yo]

Yea you right 1900 Ps is for 1.7 Ata. For standart version it was 1.55 Ata.

 

By the way, German docs never use MP specifying power rates because of its dependance of the ambient temperature and pressure even at SL. So, there is only one true table for MP I referred to.

In any other case it's necessary to use ambient conditions possibly pointed in the report text as we test the model. :)

[Endy]

The 150 grade fuel will ruin the fine balance we can see between Dora and Mustang. Additionally we have no information what was the cost for 75 inches boost regarding engine lifetime and reliability.

 

Anyway, probably Spit Mk IX with Merlin 66 can use it. Let's see...

 

Well, it depends what the ultimate aim here is, balance or historical accuracy :)

 

Speaking of which 109K should not even be in Normandy but oh well, I can understand the documentation reasons and hopefully 109G will be made as well. Though one might wonder if there are not balance reasons at play here as well then. Same as with the choice of Spit MkIX and not MkXIV.

 

Anyway, there could be options to use the 150 Octane fuel or not so people concerned with balance could choose to disable it while others might choose to use it or allow in a multiplayer session. Choices are always good :)

[Kodoss]

A little Jumo 213 history:

 

The Jumo 213A engine pre series came 1942 and was brought out in high production at August 1944 with 1750 PS (1285 KW) with a full pressure height of 5,4 km. Production stopped at the end of 1944. Fuel 87 oct.

 

At September 1944 the production of the Jumo 213C began and ended also at the end of 1944. It's similar to the 213A, but with a tunnel for the engine mounted gun and therefor changed propeller pitch device.

 

The production of the 213E with 1750 PS at sea-level (95 oct fuel, 9,8km full pressue height; 2-stage 3-gear-blower, blower air cooler with engine cooling device) was at the end 1944.

 

The 1900 PS Jumo 213 (as mentioned above) is a Jumo 213EB. Production begin was early 1945. The 213EB is a power increased Jumo 213 E .

 

The Jumo 213F was like the E, but without outer blower-air-cooling, therefor inner air cooling through MW-injection. At sea-level 2120 PS (1560 KW). Serial production in preparation.

 

The Jumo 213J is an up to 37,36 L increased and modified engine (3700 RPM, 4 valves, higher compression, increased blower, better blower-air-cooling) which were at the end of the war (in europe) construction wise nearly completed and first test engines running.

Edited September 19, 2013 by Kodoss
typo failure

[9.JG27 DavidRed]

If you do not stall the plane at 67 inches its cooling system works perfect... and I must say that 1.65 ata is not for 1750 hp (1.52 ata) but more close for 1900 hp mode.

 

+1

i just began to try the WEP 67 inches in the last two days...well at the first try, the engine seized immediately...might be because it was in the instant action mission against the Dora, and the oil and coolant temps were still below operating level...(dont know yo-yo?)

 

after that, ive not ruined my engine once with WEP, even if used for longer periods.still experimenting with it, but i seem to be able to even turn harder with the additional power.and while the Dora has never been able to climb away from me, now its funny to watch its desperated vertical barrel rolls while i gain on it with ease.

[Merlin-27]

The 150 grade fuel will ruin the fine balance we can see between Dora and Mustang. Additionally we have no information what was the cost for 75 inches boost regarding engine lifetime and reliability.

 

Anyway, probably Spit Mk IX with Merlin 66 can use it. Let's see...

 

ah, I'm happy to see this re-visited. I had mentioned it a long time ago but never heard an official response.

 

From what I know, ground crews hated the higher octane fuels because it meant full spark plug changes every two mission I believe. I don't necessarily think it's a must-have for the P-51D but maybe an option somewhere along the line?

 

and apparently...

 

Disadvantages resulting from the use of PPF 44-1 fuel in fighter aircraft may be summarized as follows:

a. Decreased spark plug life.

b. Increased rate of replacement of synthetic rubber parts in contact with the fuel.

c. Probable increase of spark plug fouling trouble under low power cruise conditions.

d. General increased engine flight line maintenance on all three engines probably resulting from the higher power operation.

e. Generally increased engine deposits and ring sticking tendencies particularly on V-1710-89 and -91 engines.

f. Higher relative toxicity of the fuel necessitates more careful handling.

 

 

 

[SlipBall]

Yo Yo

Very happy to meet you and learn about your skill's from the llya video today

[Kodoss]

Their're restoring a FW 190 D-9 at Hangar 10

 

http://www.google.de/imgres?start=241&client=firefox-a&hs=RIw&sa=X&rls=org.mozilla:de:official&biw=1188&bih=1037&tbm=isch&tbnid=TE4FlG0m1vXzCM:&imgrefurl=http://www.hobby-luftfahrt.de/cont/mus/museum_hdf.htm&docid=kQlyCBeCDen4aM&imgurl=http://www.hobby-luftfahrt.de/pic/mus/hdf/fw190_d9_02b-hdf-2012-07-08.jpg&w=380&h=253&ei=fm9EUprPH8SBtAanz4GQBA&zoom=1&iact=hc&vpx=210&vpy=246&dur=3950&hovh=183&hovw=275&tx=171&ty=94&page=8&tbnh=132&tbnw=178&ndsp=34&ved=1t:429,r:71,s:200,i:217

[Endy]

 

and apparently...

 

Disadvantages resulting from the use of PPF 44-1 fuel in fighter aircraft may be summarized as follows:

a. Decreased spark plug life.

b. Increased rate of replacement of synthetic rubber parts in contact with the fuel.

c. Probable increase of spark plug fouling trouble under low power cruise conditions.

d. General increased engine flight line maintenance on all three engines probably resulting from the higher power operation.

e. Generally increased engine deposits and ring sticking tendencies particularly on V-1710-89 and -91 engines.

f. Higher relative toxicity of the fuel necessitates more careful handling.

 

 

All of which would not be noticeable in game in any way as we do not take care of the aircraft maintenance etc.

 

I think all the historically correct systems, fuels etc. should be modelled, for all a/c in the game be it FW190 or P-51. I'm just afraid detailed simulation will be pushed aside in the name of artificial balancing, like cutting out 150 Octane fuel because that would make the pony too powerful compared to axis planes... Please don't go this route...

[Echo38]

Look, it isn't incorrect. There were P-51Ds that ran 150 fuel, but there were also P-51Ds that didn't. That they're simulating one of the ones that didn't doesn't make it wrong or a less-detailed simulation. It may be "artificial balancing," but no more than choosing the FW 190D as the opponent instead of the Me 109G or FW 190A. Your implication that the 130 fuel in the P-51 is historically incorrect is perplexing; there are two valid, historical options for the P-51's fuel, and ED has chosen the one which best makes a competitive match with the FW 190D. Such is the only logical choice for a hardcore, 100%-realism simmer who also enjoys competitive dogfighting.

 

Now, if they were pitting our lower-grade-fuel P-51 against an opponent which crushes the 130-fuel P-51, then you'd hear me hollering quite forcefully. Doubly so if said hypothetical opponent were modelled at its historical peak (or--I shudder--above). Other, lesser sim/games have done this in the past; however, I highly doubt we'll find that to be the case here when our FW 190D comes. Yo-Yo has spoken.

 

If we could have everything, I would prefer to have the option of choosing fuel grade in the mission editor. (This would allow us to experience a challenge faced by the late-war Luftwaffe, and would also allow a better VFP to handicap himself by giving his opponent the better airplane.) However, such an option would involve a ton of extra work on ED's part--not exactly a whole new aircraft, but still far from a simple tweaking of a few lines of code. This isn't a world where we can have such unnecessary luxuries, so the choice is simple: a historical portrayal that isn't balanced, or a historical portrayal that is balanced. The better choice seems clear to me. In Yo-Yo I trust!

Edited September 28, 2013 by Echo38

[Merlin-27]

All of which would not be noticeable in game in any way as we do not take care of the aircraft maintenance etc.

 

I think all the historically correct systems, fuels etc. should be modelled, for all a/c in the game be it FW190 or P-51. I'm just afraid detailed simulation will be pushed aside in the name of artificial balancing, like cutting out 150 Octane fuel because that would make the pony too powerful compared to axis planes... Please don't go this route...

 

Spark plug fouling is not only noticed on the ground :) And I personally don't think EVERYTHING needs to be modeled. I have no use for the relief tube in-game.

[NineLine]

 

If we could have everything, I would prefer to have the option of choosing fuel grade in the mission editor. (This would allow us to experience a challenge faced by the late-war Luftwaffe, and would also allow a better VFP to handicap himself by giving his opponent the better airplane.) However, such an option would involve a ton of extra work on ED's part--not exactly a whole new aircraft, but still far from a simple tweaking of a few lines of code. This isn't a world where we can have such unnecessary luxuries, so the choice is simple: a historical portrayal that isn't balanced, or a historical portrayal that is balanced. The better choice seems clear to me. In Yo-Yo I trust!

 

 

Yup, I would like to see this, limited quantities of the fuel with the resource manager....