# Dornier 217 hypothetical



## wiking85 (Feb 8, 2013)

What if this aircraft had the DB603 as a power plant, having not been cancelled in 1937, available in 1941 with about 1650hp and the reliability it achieved in late 1943, and never had dive bombing as part of its mission/design profile? Would it have had better performance without the dive requirement and available earlier without the dive testing and redesigns? What about with the DB603 being unreliable, but in production in 1940?
How soon could it have been available and what would it have replaced? I imagine it would have the performance of the Do217M in 1942 when the DB603 historically produced 1750hp, but in 1941 would have had somewhat reduced performance.
http://en.wikipedia.org/wiki/Dornier_Do_217#Specifications_.28Do_217_M-1.29



> Specifications (Do 217 M-1)
> 
> General characteristics
> Crew: 4
> ...


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## Denniss (Feb 9, 2013)

A DB 603 that early would be impossible as DB had more than enough problems with their DB 601, both in development and production. Invest more money and manpower into DB 601 and German a/c manufacturers may have been flooded with DB 601 engines and DB 605/603 may have been available a little bit earlier.

But yes, the dumb dive bombing requirement for both Do 217 and He 177 increased cost and development time a lot while negatively affecting a/c performance.


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## davebender (Feb 9, 2013)

Late 1930s Jumo 211 had three engine factories (Dessau, Magdeburg, Kothen). Two more relatively large Jumo engine plants opened in 1942 at Leipzig and Stettin.

DB601 had a single modest size factory at Genshagen prior to 1940.

Give Daimler-Benz engine program resources similiar to Jumo engine program and I'll hazard a guess Daimler-Benz engine development would be considerably faster then historical.


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## wiking85 (Feb 9, 2013)

davebender said:


> Late 1930s Jumo 211 had three engine factories (Dessau, Magdeburg, Kothen). Two more relatively large Jumo engine plants opened in 1942 at Leipzig and Stettin.
> 
> DB601 had a single modest size factory at Genshagen prior to 1940.
> 
> Give Daimler-Benz engine program resources similiar to Jumo engine program and I'll hazard a guess Daimler-Benz engine development would be considerably faster then historical.



Any idea when the Jumo factories were built? I thought it was in the late thirties and prior Daimler and Jumo were not much different in size until the RLM decided to bult extra factories for Jumo, but not Daimler.


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## davebender (Feb 9, 2013)

Junkers Engines - Jumo 211
Dessau 1086 prototypes, test engines
Magdeburg 24267 July 1937 to Aug. 1944
Kothen 20911 1938 to Feb. 1944
Leipzig 17032 1942 to Aug. 1944
Stettin 4714 only 1942
Strassburg 238 1943 to Feb. 1944 

The large Stettin factory (about 400 engines per month) produced Jumo 211s only during 1942 because Germany had more Jumo 211 engines then they could use. 

IMO the Stettin factory should have been producing 400 DB603 engines per month from 1941 or 1942 until the end of the war.


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## davebender (Feb 9, 2013)

Let's use historical RLM standard for BMW801 engine.
BMW 801 - Wikipedia, the free encyclopedia
1,539hp. 
Engine service life of 30 to 40 hours.

Our early model DB603 engine will enter mass production when it can pass a 50 hour endurance test @ 1,540hp while running on B4 fuel.

Next version of DB603 engine will enter mass production when it can pass a 100 hour endurance test @ 1,680hp while running on C3 fuel.


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## wiking85 (Feb 9, 2013)

I think that late 1940 for the first benchmark is not unreasonable. The engine historically was started in 1936 and cancelled in 1937; it restarted in 1940 and was able to complete the 100 hour test in late 1943. Altogether that is about 5 years of development, as very little was done in the years 1937-1940 with the engine other than adapt it to a short landspeed record in a race care that never took place.
Assuming funding isn't interrupted in 1937 and in fact increases, then the unit by mid-1940 will have five years under development; that time period would correspond with the historical 1942 version, which was in service and IIRC passed the 50 hour test. 
Perhaps late 1940 is too ambitious, though that would have been over 4 years of development by then. By mid-1941 though that would have been 5 years of development, which was the historical amount of time it took to make the DB603 reach 100 hours endurance. By 1942 in this scenario it would have have 6 years of development, so would be fully reliable by then and broken in.


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## davebender (Feb 9, 2013)

That would change a lot more then just Do-217 program. Focke Wulf and Messerschmitt aircraft designs would take advantage of DB603 engine. Junkers would be running scared that their Ju-88 would get Daimler-Benz engines rather then Jumo engines.


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## wiking85 (Feb 9, 2013)

davebender said:


> That would change a lot more then just Do-217 program. Focke Wulf and Messerschmitt aircraft designs would take advantage of DB603 engine. Junkers would be running scared that their Ju-88 would get Daimler-Benz engines rather then Jumo engines.


Of course, but the Ju88 would need to be adapted to handle the larger engine, while the Do-217 would offer better payload and range than the Ju88/188 with a Db603. Plus initially it would mean the Db603 would be relatively scarce, so in late 1940 (October or so) it would go to testing for the Do-217, Ju-188, and Fw190C rather than operational units. As it gets more production and becomes more reliable in mid-1941 then we would see operational Do-217Ms (the E-series with the BMW 801 would enter service in March 1941 historically, maybe earlier here if the airframe is ready sooner because of the lack of the dive requirement).

The Fw190C is IMHO not likely before some time in mid-1942. 

The Ju-288 could see operational status with the DB603 perhaps in 1943 when the Jumo 222 is cancelled. 

Is it possible that that Db603 has greater horsepower than historical versions in 1943-44? The greater development time seems to make it more likely IMHO. 
Perhaps the Do-217 here, thanks to taking both the Db603 and BMW 801 and having greater range, speed, and payload than the Ju88 might start to over take it deeper in the war?


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## davebender (Feb 9, 2013)

That depends on when the engine starts to look promising. 

It's my understanding DB603 prototype #1 was producing 1,500 or 1,550hp during 1937 when program funding was cancelled. Construction of a Genshagen size factory (220 engines per month) could start in 1939 with production beginning early 1941.

Stettin factory begins producing 400 engines per month during 1942 just as it did historically. Except in this scenerio they are DB603 engines rather then Jumo211. By mid 1942 Germany would be producing 600 DB603 engines per month.


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## Shortround6 (Feb 9, 2013)

wiking85 said:


> Is it possible that that Db603 has greater horsepower than historical versions in 1943-44? The greater development time seems to make it more likely IMHO.



Not likely without some other changes. Development can only do so much. Power is limited by the rpm, the pressure in the cylinders and the size of the cylinders. The size of the cylinders is pretty much fixed or you are dealing with a new engine with new vibration patterns/problems. Cylinder bore is pretty much already at the maximum without going to triple ignition. Length of stroke is already on the high side for a WW II aircraft engine which helps limit RPM. Big cylinders are harder to cool than small ones, more volume for fuel/air per unit of area of cylinder wall/piston crown and cylinder head. This leaves pretty much increasing the pressure in the cylinders through higher boost. Pressure in the cylinders is limited by the available fuel. MW 50 can only do so much. Germans could have lowered the compression and used more boost for more power but that cuts fuel economy. 

Please note that while a certain few engines did post very large increases in power over their history they usually started in the mid to late 30s with 87 octane fuel and went on to use 100/130 or above, some with major modifications. Engines that started in the very late 30s or 1940/41 showed a much smaller increase in power due to starting with 100 octane fuel to begin with. The P&W R-2800 was air cooled ( which may have helped limit it's power ) but it started at 1850hp, went to 200ohp very quickly and despite a total redesign that kept _only_ the bore and stroke ( aircraft engine designers were _very_ loath the change those numbers) only a couple of models went over 2500hp even by the time of the Korean war and using 115/145 fuel or 130/100 and ADI. 

Please also note that the Jumo 213 was in a lot of ways a "developed" 211. But look at the amount of weight it gained while being developed. 

They might have been able to get more power from the 603 but some "development paths" are going to come with costs; worse fuel consumption or higher weight ( or both?) Maybe they are worth it, maybe not.


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## Denniss (Feb 10, 2013)

Junkers was state-owned while DB was a private company, quite natural that Junkers got more money especially as the big fat man wanted bombers.
An early 1940 DB 603 would most probably lack many of the advanced features developed for the DB 601N and E such as pressurized water cooling, the redesigned cylinders, etc. Power with B4 would hardly exceed 1600PS and it would require large radiators for cooling.


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## tomo pauk (Feb 10, 2013)

Since the DB-603 of early 1941 would be offering notably less power than the DB-603 of late 1942, it will offer no advantage over the BMW-801A? Let alone when we account for greater weight of the 603.


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## wiking85 (Feb 10, 2013)

Denniss said:


> Junkers was state-owned while DB was a private company, quite natural that Junkers got more money especially as the big fat man wanted bombers.
> An early 1940 DB 603 would most probably lack many of the advanced features developed for the DB 601N and E such as pressurized water cooling, the redesigned cylinders, etc. Power with B4 would hardly exceed 1600PS and it would require large radiators for cooling.


Jumo was a separate company from Junkers at some point, so I'm not sure if Jumo was owned by the state when they took over Junkers.
As to the 1940 Db603, you're right that it wouldn't have those features in the A-series, but in the 1941 it would.



tomo pauk said:


> Since the DB-603 of early 1941 would be offering notably less power than the DB-603 of late 1942, it will offer no advantage over the BMW-801A? Let alone when we account for greater weight of the 603.


http://en.wikipedia.org/wiki/BMW_801


> Dry weight: 1,012 kg (2,226 lb)



http://en.wikipedia.org/wiki/Daimler-Benz_DB_603


> Dry weight: 920 kg (2,030 lb)



It seems the 603 weighed nearly 100kg less than the BMW 801. Also the 1940 version of the DB603 would likely not be as heavy because of the lack of features mentioned by Denniss, making it even lighter. The 1941 version would be as heavy as the weight I have listed here, but it would also have the extra features AND more horsepower, offsetting the weight.
Not only that, but as a liquid cooled engine it would have better altitude performance, as the BMW 801 air cooled engine's horsepower dropped off significantly above 20,000 feet.


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## tomo pauk (Feb 10, 2013)

wiking85 said:


> It seems the 603 weighed nearly 100kg less than the BMW 801. Also the 1940 version of the DB603 would likely not be as heavy because of the lack of features mentioned by Denniss, making it even lighter. The 1941 version would be as heavy as the weight I have listed here, but it would also have the extra features AND more horsepower, offsetting the weight.



The weight of cooling system need to be added to the DB-603, and then we can compare. For the P-40, for example, the weight of cooling system was circa 300 lbs, maybe up to 350 lbs for the DB-603? I agree that a pre-603 would be lighter than the 603 of ~1943, so maybe a whole powerplant would be of the same weight when either pre-603 or early 1941.
Shouldn't the non-pressurrised cooling system weight more than a pressurrised?



> Not only that, but as a liquid cooled engine it would have better altitude performance, as the BMW 801 air cooled engine's horsepower dropped off significantly above 20,000 feet.



Whether the engine is liquid cooled, or air cooled, has nothing to do with altitude performance. That's a prerogative of supercharger system, ability of the engine to make high RPM, and it's about the displacement. The liquid cooled engine without pressurised cooling system will suffer at altitude.


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## wiking85 (Feb 10, 2013)

tomo pauk said:


> The weight of cooling system need to be added to the DB-603, and then we can compare. For the P-40, for example, the weight of cooling system was circa 300 lbs, maybe up to 350 lbs for the DB-603? I agree that a pre-603 would be lighter than the 603 of ~1943, so maybe a whole powerplant would be of the same weight when either pre-603 or early 1941.
> Shouldn't the non-pressurrised cooling system weight more than a pressurrised?


Why does the cooling system weight have to added? Why wouldn't it be included in the weight of the unit? Are you talking then about the fuel that would be part of the engine, the 'wet weight'?
What about the BMW 801's cooling system?


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## tomo pauk (Feb 10, 2013)

It needs to be added to the dry weight:


> Dry weight: 920 kg (2,030 lb)


quote from Wikipedia.

Since without the cooling system the liquid-cooled engine is worth nothing, it would be a god idea to add it 
Fuel system was not the part of 'dry weight' too, neither was lubrication system, those two would vary from airplane to airplane. The cooling system of the air cooled engine is, well, dry (fins and that, plus fan), that makes it included into dry weight.


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## davebender (Feb 10, 2013)

> Junkers was state-owned while DB was a private company, quite natural that Junkers got more money


The dispute concerned what Daimler-Benz was to manufacture.

RLM wanted Daimler-Benz to quit manufacturing automobiles and concentrate almost entirely on aircraft engine production.

Daimler-Benz wanted to remain diversified to improve chances for long term survivability and profitability. Daimler-Benz management were especially determined to keep manufacturing automobiles.

Personally I think RLM handled this matter foolishly. WWII era German armed forces needed all the 3 ton trucks they could obtain. Giving Daimler-Benz a long term contract for 500 or 1,000 diesel powered 3 ton 4WD trucks per month would have bought peace and helped the Wehrmacht too.


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## davebender (Feb 10, 2013)

More to it then that. 

Aircraft which employ large air cooled engines require a larger then normal engine compartment to facilitate air flow. Fw-190 is a good example of this. Engine compartment had to be enlarged to solve cooling problems. I'd hazzard a guess fuselage size increase adds as much or more aircraft weight as a liquid cooling system.


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## tomo pauk (Feb 10, 2013)

It depends what engines are compared with, in this case, BMW-801. Ie. the DB-603 was a big engine on it's own, far bigger than the DB-601/605.


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## davebender (Feb 10, 2013)

DB603 engine was heavy but it had a surprisingly small height and width. That makes for a relatively slim engine compartment. 

Air cooled radial engines are fat and space requirements for cooling air make the engine compartment even larger. All U.S. fighter aircraft powered by R-2800 engine had a huge fuselage and all were relatively heavy.

*Engine Frontal Area *(sq. ft.)
5.4. DB601E
5.5. DB605A.
5.8. Merlin X
6.1. Merlin 61.
6.1 to 6.2. Allison V1710 series.
6.3. Ju213A.
6.9. DB605D
7.0. DB603A
7.5. Merlin 66
12.6. P&W R1830
13.4. R2000
14.7. BMW801D.
15.0. R2800
16.0. R2600.


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## tomo pauk (Feb 10, 2013)

Thanks for the numbers. I can readily agree that radials were always draggier, even when we count in the cooling system, not listed in your list. We can also note that BMW-801 was one of least draggy radials, and radiator installation in historical Do-217 was not something to brag about.


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## davebender (Feb 10, 2013)

Do-217M was mass production bomber (431 produced during 1943) powered by DB603 engines.

I know nothing about this aircraft's cooling system. What don't you like?

Dornier Do 217 M, Italeri 1/72 - Ready for Inspection - Aircraft - Britmodeller.com


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## Milosh (Feb 10, 2013)

Why is there such a difference between the DB605A (5.5) and the DB605D (6.9)?


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## tomo pauk (Feb 10, 2013)

davebender said:


> Do-217M was mass production bomber (431 produced during 1943) powered by DB603 engines.
> 
> I know nothing about this aircraft's cooling system. What don't you like?



Thanks for the pics.
What I don't like is that it ups the power plant frontal area some 50%, give or take.


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## davebender (Feb 10, 2013)

How much is typical? 

DB603 powered Me-410A should provide a direct comparison. Perhaps we could also look at Lancaster Bomber and divide by two as it has 4 engines.


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## tomo pauk (Feb 11, 2013)

The 'typical' increase of power plant area would depend upon the size layout of the coolers. 

For the Do-217, we need to account for also the oil cooler (atop of the engine), the BMW-801 having oil cooler 'wrapped around', located inside the cowling.
The Lancaster (and Halifax and Beaufighter) might or might not give us a clue, radial vs. in-line re. Do-217. The BMW-801 was renown as a streamlined powerplant (vs. Hercules, R-2800 etc), with tight cowling. On the other hand, the Merlin was a smaller engine than DB-603, needing also smaller Prestone and oil cooler.


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## davebender (Feb 12, 2013)

*Chromium. October 1944.*
19.01kg. DB605.
21.95kg. DB603.

*Nickel Requirements.*
9.82kg. DB603. Oct 1943.
2.16kg. DB603. May 1944.

It appears to me Daimler-Benz did an outstanding job designing DB603 engine for low cost mass production. A bit more expensive then the relatively cheap DB605 but not much more and almost certainly less expensive then BMW801 radial engine.


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## Gixxerman (Feb 12, 2013)

I always liked the look of the late Do 217's, pretty mean looking bombers.
I seem to recall reading in several places that they were always underpowered.
They did seem to be the heaviest of the LW's 'medium' bombers though (a bomb load of 4,400kg seems to be quoted a lot = almost 9,000lb).

It always amazes me seeing the production numbers, as with so many German bombers there seem to have been hundreds of each sub-type made (amounting to thousands of bombers) and yet what did they do with all those late war Ju88's, Ju188's, Do 217's, He 177's etc etc?

I have read that the bomber arm of the LW was the most prestigeous part of the LW and yet once the initial victories were done spent (until end 1942/Stalingrad?) it seems to have done very little besides Steinbock.
Perhaps there's a whole side to it (presumably in the east) that has gone unreported?
They must have done something with them (surely they weren't all wasted as transports hacked out of Stalingrad skies)?


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## wiking85 (Feb 12, 2013)

Gixxerman said:


> I always liked the look of the late Do 217's, pretty mean looking bombers.
> I seem to recall reading in several places that they were always underpowered.
> They did seem to be the heaviest of the LW's 'medium' bombers though (a bomb load of 4,400kg seems to be quoted a lot = almost 9,000lb).
> 
> ...



In 1943 there was a switch largely to fighters, including the Do-217 night fighter, which was a waste of the aircraft IMHO, as it was far too heavy for that role and could have been useful on the Eastern Front.
By 1943 LW bombers were operating in the Mediterranean, on the Eastern Front, and against Britain in air raids, including the Do-217 in those. By 1944 the bomber arm for the LW had been decimated and was operating sporatically in Italy and France, while mostly being confined to the Eastern Front due to Western Allied air supremacy. In 1944 it was almost exclusively fighters that were being churned out and bombers were around 10% of production, meaning even those bombers that were left were often sidelined due to lack of spare parts or fuel, not to mention lack of replacement aircraft.

I think the Do-217 had a narrow window of usefulness in 1941-43 given the historical political decisions being made, poor military planning, and very poor development decisions that prevented aircraft like the Do-217 having powerful enough engines. If it had the originally planned Jumo 222 available in 1942 as initially planed (2000hp version), rather than the Jumo 222 being constantly modified to produce more power as demanded by the LW, it would have had plenty of power for the roles expected of it. Even having the DB603 ready in 1941-42 would have been a massive boon to this type, as it would have offered more power than what was available historically at the time. But even then the DB603 at 1750hp that was tested by Eric Brown (Dornier Do 217 - Wikipedia, the free encyclopedia) was apparently too little for the type. Of course the dive requirement upped the weight and slowed development, which would be different with this scenario's version of it, which wouldn't have been strengthened for a role it was never able to effectively perform. So perhaps a DB603 would have been just right for the Do217 without the dive requirement.


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## davebender (Feb 12, 2013)

Arado Ar 232 - Wikipedia, the free encyclopedia
Personally I think Dornier missed the boat by not making a 4 engine variant powered by Bramo 323 engines. Change would be similiar to Ar-232.

*Ar-232 Early Version.* 2 x BMW801 engines.






*Ar-232 Late Version.* 4 x Bramo 323 engines.






Change to four engines worked exceptionally well for Ar-232. So well in fact that there were plans for a 6 engine version. Arado's good work was for nothing because RLM refused to allow production of Ar-232 transport. 

Converting Do-217 to 4 x Bramo 323 engines has additional advantage of not requiring a new engine to be developed. Just increase production of existing Bramo 323 engine.


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## johnbr (Feb 12, 2013)

I so a doc that showed at one time it was to get the BMW 802 in it.


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## Denniss (Feb 13, 2013)

The Bramos would not be sufficient for the Do 217 - not enough power.
They could have used the Jumo 211 though.
But going from 2 to 4 engines will required a wing redesig, at least it has to be longer and stronger.
And as long as the dive bombing requirement was upheld, no chance for a 4-engine version.


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## tomo pauk (Feb 13, 2013)

The four Bramos in Fw-200 have had the same take-off power as the engines for the B-17 and B-24...


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## Vincenzo (Feb 13, 2013)

On the underpowererd
the BMW 801 engined Do 217 is a 1941 bomber, what twin engined bomber with similary load capability had best power load in that time? or when were available so bombers with best power load?


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## Denniss (Feb 13, 2013)

tomo pauk said:


> The four Bramos in Fw-200 have had the same take-off power as the engines for the B-17 and B-24...


But these engines could hold power high-up, only the two-stage Bramos could keep a good alt performance up to the usual levels of ~5 km. The 1200PS were only possible for a very short time with C-3 or MW-50, real power without boosting was 1000PS


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## tomo pauk (Feb 13, 2013)

> But these engines could hold power high-up, only the *two-stage Bramos* could keep a good alt performance up to the usual levels of ~5 km.



Is that a typo, two stage Bramos?
The US heavies were twice as big airplanes as the Do-217, with much more crew and gun armament. Granted, the fictitous 4-engined Dornier would not be as small as the DO-217, but again not as big the US heavies, if the defensive armament and crew is kept at reasonable level in the design phase. Or, they might go to a full-size 4-mot, a rough equivalent of the French MB.162?


> The 1200PS were only possible for a very short time with C-3 or MW-50, real power without boosting was 1000PS



Okay - so the 1st versions of the 4-engined Dornier would feature the 1000 PS engines, later increasing to 1200 PS. 
BTW - is there an easily obtainable data resource about the Bramos?


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## wiking85 (Feb 13, 2013)

davebender said:


> Arado Ar 232 - Wikipedia, the free encyclopedia
> Personally I think Dornier missed the boat by not making a 4 engine variant powered by Bramo 323 engines. Change would be similiar to Ar-232.
> Change to four engines worked exceptionally well for Ar-232. So well in fact that there were plans for a 6 engine version. Arado's good work was for nothing because RLM refused to allow production of Ar-232 transport.
> 
> Converting Do-217 to 4 x Bramo 323 engines has additional advantage of not requiring a new engine to be developed. Just increase production of existing Bramo 323 engine.



So basically a developed Do-19 worked on from 1936 instead of starting the Do-217 in 1937. I think we could refer this back to my Do-219 thread in that case.


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## davebender (Feb 13, 2013)

> They could have used the Jumo 211 though.
> But going from 2 to 4 engines will required a wing redesig, at least it has to be longer and stronger.


If Germany wanted a bomber powered by four Jumo 211 engines they would produce the He-177B proposed in 1938.

525kg. BMW 132 dry weight.
550kg. Bramo 323 dry weight.
720kg. Jumo 211F.
920kg. DB603A dry weight.
1,012kg. BMW 810 dry weight.
.....Two Bramo 323 engines weigh little more then one BMW 801 engine. That's probably why the Ar-232 engine change worked so well. The wing doesn't need to be strengthened, as would be the case if heavier Jumo 211 engines were installed.


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## wiking85 (Feb 15, 2013)

Back to the DB603 as a potential engine by 1940:
I just got a new book that adds a bit more info and seems to think that 1940 was the year the engine would be operational. Apparently it was first offered in September 1936 as a development of the DB601, which had yet to enter serial production, but was progressing to that point within a year. But Udet cancelled the DB603 in March 1937; had the engine been kept in development, there seems little reason that it couldn't enter serial production by September 1940 and that it would produce some 1600hp at that period, bumping up to 1750hp the following year as the improvements from the DB601N and DB601E/F are phased into the larger engine.

As it was from the first contract to develop the DB600 series of engines in 1933 to serial production of the DB601A in November 1937 was close to 4 years. The first bench test for the DB603 would have been in 1938, which meant usually that within 2 years of a successful bench test the engine was ready for mass production. Historically with little financing and support the DB603 went from a bench test in 1939 to mass production in 1941, though because of the limited support for it, Daimler didn't dedicate the required engineering resources to it despite it jumping in horsepower output, thus experiencing heating issues when it exceeded the horsepower it was initially designed to produce.

Here the engine would stick to spec by the time it would enter serial production in late 1940, so wouldn't experience those overheating issues; they would crop up as it was upgraded in 1941 of course, but assuming it was valued more highly by the RLM, it wouldn't take as long to work them out. That would mean the Dornier 217 could have a functional engine of the 1600hp class and enter serial production in 1940.


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## J.A.W. (Mar 17, 2013)

A couple of points for consideration re Do 217;
1, A fast ship - say compared to a B-25 or even B-26, on the straight level, cant`ve been too 'under-powered' -maybe Brown didn`t like twins per se?
2, A faster ship, going downhill, being built stress-capable of dive-bombing meant the Do 217 had pretty good G-factor limits, including V-ne ratings, which gave some tactical options the B-25/B-26 could not match, or for maybe even evading an NF Beaufighter during Baedeker, `43..


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## davebender (Mar 17, 2013)

Depends on what you are comparing. I suspect Eric Brown was thinking in terms of Me-410, Mosquito and Ju-88G light bombers. Larger Do-217 won't have the same power to weight ratio using similiar engines.

If you want Do-217 to perform like a Ju-88G then it needs Jumo 222 engines. Then it would have the power to fly with one engine shot out.


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## Shortround6 (Mar 17, 2013)

In a single engine plane if you loose the engine the plane is going down.

In a twin engine plane it depends a lot on the power loading. Some twins will fly rather nicely on one engine ( once trimmed out), others even when trimmed and balanced have a _ negative _ rate of climb on one engine= plane looses altitude even with the engine at full power and flying straight and level. Any maneuver, even a gentile turn, causes a lost of lift and an increase in drag. 

Speed does not equal "high power", it equals low drag. Allison powered Mustangs were very fast but had a poor power to weight ratio and didn't climb well. P-40s gained speed over the P-36 but gained little power and a lot of weight. They went faster but didn't climb as well. 

Twin engine bombers often had 4-7 man crews. Loosing and engine on take-off in an under powered twin could result in the loss of both the aircraft and crew. A plane with a bit more power may give the pilot enough time to trim the plane out and do a circuit to get it back on the ground. Plane probably isn't high enough for the crew to bail out. 

The British made their share (and more?) of under powered twins.


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## J.A.W. (Mar 17, 2013)

Didn`t Robin Olds say something like " I sometimes got home from Germany on 1 engine - flying the P38 , but I always got back on 1 engine, flying the P-51.."

Some twins were tricky on one mill, even a fairly high powered job, like the Mosquito, being critical in engine failure V 1 rotate situations, due to assymetric aero issues.
Speed is still a factor of power/drag, maybe the DH designers really got it right with deletion of defensive armament on their Mosquito.

I recall reading about a canny veteran Do 217 skipper who lightened his machine as much as possible, inc losing guns [ gunner] - since he reckoned that a determined fighter pilot will invariably press in hard, no matter what you throw back at him, evading attacks by using a performance edge was a better bet..


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## johnbr (Sep 7, 2017)



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## vikingBerserker (Sep 7, 2017)

Nice!


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## Old Wizard (Sep 7, 2017)




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## J.A.W. (Apr 13, 2018)

Sadly, although there is no intact Do 217 to see, the USA has a ex- Do 217 BMW 801 'power-egg' on display,
interestingly, the BMW 'kommandogerat' unified control system was also used on the bomber mills..

That must've helped in flying the machine if A2A combat was in prospect, & was in advance of most US fighters..


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