Which was better the Do-217 or Ju-188?

[wiking85]

In terms of capabilities the Do-217 seems to have had greater potential than the later Ju-188, despite the latter's adaptability and easier conversion of the existing production lines. What arguments are their for the Ju-188 over the Do-217 as a medium bomber if any (other than ease of converting existing Ju-88 production lines)?
https://en.wikipedia.org/wiki/Dornier_Do_217#Specifications_.28Do_217_M-1.29

Specifications (Do 217 M-1)[edit]
General characteristics
Crew: 4
Length: 17.00 m (55 ft 9 in)
Wingspan: 19.00 m (62 ft 4 in)
Height: 4.96 m (16 ft 3 1⁄2 in)
Wing area: 57.00 m2 (613.54 ft2)
Empty weight: 9,100 kg (20,062 lb)
Max. takeoff weight: 16,700 kg (36,817 lb)
Powerplant: 2 × DB 603A 12-cylinder inverted-vee engine, 1,750 PS (1,726 hp, 1,287 kW) each
Performance
Maximum speed: 557 km/h at 5,700 m (347 mph at 18,700 ft)
Cruise speed: 400 km/h (248 mph)
Range: 2,145 km (1,332 mi)
Service ceiling: 7,370 m (24,180 ft (with max bombload))
Rate of climb: 210 m/min (688 ft/min)
Armament
4 × 7.92 mm (.312 in) MG 81 machine guns in nose and lateral positions
2 × 13 mm (.51 in) MG 131 machine guns in dorsal and ventral positions
Max Load 4,000 kilograms (8,800 lb) internally externally.
Max Internal Load 3,000 kilograms (6,600 lb).

https://en.wikipedia.org/wiki/Junkers_Ju_188#Specifications_.28Ju_188E.29

Specifications (Ju 188E)[edit]
General characteristics
Crew: 5
Length: 15 m (49 ft 1 in)
Wingspan: 22 m (72 ft 2 in)
Height: 4.4 m (14 ft 7 in)
Wing area: 56 m² (603 ft²)
Empty weight: 9,900 kg (21,825 lb)
Loaded weight: 14,500 kg (31,967 lb)
Powerplant: 2 × 1 BMW 801 G-2, 1,700 PS (1,250 kW) each
Performance
Maximum speed: 499 km/h (310 mph)
Range: 2,190 km (1,360 mi combat)
Service ceiling: 9,500 m (31,170 ft)
Wing loading: 258.9 kg/m² (53.0 lb/ft²)
Power/mass: 0.175 kW/kg (0.106 hp/lb)
Armament
Guns: 1 × 20 mm MG 151/20 cannon
3 × 13 mm (.51 in) MG 131 machine gun
Bombs: 3,000 kg (6,612 lb)

 

[Juha]

Ju 188 was easier to fly and 217 had problems with rather weak undercarriage.

 

[Koopernic]

In terms of capabilities the Do-217 seems to have had greater potential than the later Ju-188, despite the latter's adaptability and easier conversion of the existing production lines. What arguments are their for the Ju-188 over the Do-217 as a medium bomber if any (other than ease of converting existing Ju-88 production lines)?
https://en.wikipedia.org/wiki/Dornier_Do_217#Specifications_.28Do_217_M-1.29


https://en.wikipedia.org/wiki/Junkers_Ju_188#Specifications_.28Ju_188E.29

A slightly fairer comparison is with the Junkers Ju 188A which entered service after the Ju 188E but with Jumo 213A engine. It was slightly faster at 322mph though it was quite late entering service.

The 347mph speed of the Do 217M is impressive. If they had of fitted some of the more advanced engines developed for fighters they might have seen speeds of 400mph eg
DB603E 1800hp (only slightly more than DB603A but at a critical altitude of 8.1km instead of 5.7 so the higher you go the bigger the power advantage)
DB603EM 2250, designed for the Ta 152C and required C3 and MW50 to achieve this, abandoned due to fears of C3 fuel shortages. I suspect this engine would have driven the aircraft to 377mph.
DB603LA between 2250 and 2500hp
DB603N up to 2800hp.


One of the higher points of the Luftwaffe was its use of guided bombs from 1943 to 1944, for some reason the Ju 188 was never used.

In 1944 the Luftwaffe is dumping most of its piston engined bombers and betting on jets.

The Ju 388 survived because it could cruise at such high altitudes, could be used as a night fighter to combat the B29 should that aircraft be deployed and it was obviously a Ju 188 derivative. Variants with other engines such as the Jumo 213, jumo 222A/B, EF etc promised speeds of over 440mph at lower altitudes.

Single engined aircraft such as the Fw 190 could blind bomb using the EGON system and were getting computing bomb sights and this is where the Luftwaffe was heading: single engined aircraft or jets with the Ju 388 and Dornier Do 335 remaining the only twin piston engine aircraft on the manufacturing program.

 

[davebender]

Real bomb bay. Do-317 version also had a lot more engine power which translates into greater range / payload.

 

[wiking85]

Real bomb bay. Do-317 version also had a lot more engine power which translates into greater range / payload.

With much heavier engines that didn't work properly. Also the 317 didn't first fly until 1943 and was a development of the Do217. It was a later design than the two types in question and not part of this discussion for that reason.

Now, as to the original question, I appreciate the responses, they've been enlightening. Juha what's the source for the easier to fly statement and the weaker undercarriage?

Beyond that would it have made more sense to just make Ju188s with the BMW 801 and later DB603 and Jumo 213, rather than make both the Do217 and Ju188? It seems like they did duplicate work and the Ju188, though slower with the 801s rather than the DB603 powered 217, required major retooling that the 188 did not. Rather the mass existing Ju88 lines could mostly be used with some modification to the cockpit, tail, and wing assemblies along with general retraining. I know the Ju288 delayed the 188 from entering service until much later than the 217, though the 'definitive' 217 entered production in 1943 alongside the 188. Perhaps the reason both were made was due to the 217 already being in production on different lines and the 188 being brought in belatedly to improve existing Ju88 production with minimal disruption? Perhaps that was the only option to ensure output was still reasonable, rather than standardizing on one type? I know Milch was very serious about ensuring that one company did not dominate the airframe production too much to create a monopoly, so perhaps politics was involved...

Anyway, would it have made made sense, assuming there was a rational plan, not to halt Ju88 development in 1940 in favor of the 288, not make the 217 and just shoot for the 188 for 1941/2 as Germany's sole twin engine bomber given the state of technical development at the time? It would have taken probably until 1943 to phase out the other types, while not producing the 217, and phase in the higher powered engines like the DB603, Jumo 213, and expand BMW 801 production.

 

[davebender]

Ju-188 entered service during 1943 and it's a variant of the Ju-88. In both cases were are talking about aircraft (Do-217/Do-317 and Ju-88/Ju-188) which entered (or could have entered) service during 1943 and shared components with an earlier aircraft.

 

[wiking85]

Ju-188 entered service during 1943 and it's a variant of the Ju-88. In both cases were are talking about aircraft (Do-217/Do-317 and Ju-88/Ju-188) which entered (or could have entered) service during 1943 and shared components with an earlier aircraft.

I think you're misunderstanding the 'first flew' idea, which was when the first prototype was ready and flying. That means serial production is about 2 years away assuming prototype development goes well. So in reality it was a 1945 type, rather than a 1943 one. The Ju188 was developed and in serial production/service in 1943:
Junkers Ju 188 - bomber, reconnaissance aircraft
It would have been ready in late 1941/1942 had development not been frozen in 1940, though continued by Junkers with limited funds on its own.

They really aren't comparable aircraft at all, either in time of usage.

 

[Juha]

Hello Viking

Eric Brown, he didn't like Do 217M but was very impressed by Ju 88G, not in fact 188 but a Ju 88 with 188's tail and engines. Even Beaumont was very impressed by 88G. The problems with the 217 undecarriage comes from Griels' Do 217 - 317 - 417 and Aders' History of the German Night Fighter Force.

Juha

 

[davebender]

Eric Brown's Do-217 flight description suggests he was expecting fighter aircraft performance. Not surprisingly, Do-217 medium/heavy bomber aerial performance didn't compare well. If comparison had consisted of placing 3,000kg of ordnance on a target 500 miles away with a high cruise speed then Do-217 performance starts to look a lot better.

 

[wiking85]

Eric Brown's Do-217 flight description suggests he was expecting fighter aircraft performance. Not surprisingly, Do-217 medium/heavy bomber aerial performance didn't compare well. If comparison had consisted of placing 3,000kg of ordnance on a target 500 miles away with a high cruise speed then Do-217 performance starts to look a lot better.

Was the Do217 cruise speed that much better? I cannot find it anywhere online.

 

[Juha]

Eric Brown's Do-217 flight description suggests he was expecting fighter aircraft performance. Not surprisingly, Do-217 medium/heavy bomber aerial performance didn't compare well. If comparison had consisted of placing 3,000kg of ordnance on a target 500 miles away with a high cruise speed then Do-217 performance starts to look a lot better.

I'm not sure of that, Even if he was a fighter pilot by training when he flew 217M he had participied tests flown by at least B-17, B-24, B-25, Stirling, Halifax, Lancaster, York, Wellington and Warwick, the last mentioned was the nearest British equivalent to 217. And in the same time frame as he flew 217 he also flew He 177, Fw 200 and heavy LW flying boats. Ju 88 he had flown earlier. So he had fairly good recent experience on heavy multi-engine planes when he tested 217.

Juha

 

[davebender]

Dornier Do 217 - Wikipedia, the free encyclopedia

October 1945 British Captain Eric Brown undertook full handling trials with a Do 217 M-1 WNr 56158 at RAF Farnborough. He recalled a distinctly "underwhelming" experience.[99] Brown recalled that he took off with full power of some 2,700 rpm and the lightly loaded Do 217M left the runway at 160 km/h (99 mph). Brown held a shallow climb, waiting to reach 200 km/h (120 mph) before retracting the undercarriage. Brown timed the time it took to retract, which was between 30 and 40 seconds.[99] At 150 m (490 ft) he reduced power to 2,500 rpm and raised the flaps at about 230 km/h (140 mph). With the flaps up a climbing speed of 230 km/h (140 mph) was established giving a rate of "very moderate proportions".[

How does climb performance of Do-217 bomber compare with those aircraft when carrying similar size bomb load and a full load of fuel?

 

[Juha]

Dave
it's always better to read the original article than base one's oppinion to what is in wiki. Brown's main complain on 217 was that he thought it was underpowered twin and he definitely didn't like underpowered twins because they were inherently dangerous during t/os and landings and IMHO to Brown t/o and landing characteristics were very important maybe because of his naval pilot backround.