Effects of a mass produced Do26?

[wiking85]

I've asked some similar questions in the past:
http://www.ww2aircraft.net/forum/av...r-long-range-naval-recon-do19-ju89-34930.html
http://www.ww2aircraft.net/forum/av...on-long-range-naval-reconnaissance-34171.html
But not directly this one:
What if the Germans produced the Do26 in numbers and used it for their naval reconnaissance instead of the FW200 and later Ju290 (among others)? Production could begin in 1939, when the model became fully available; historically only 6 were produced, but they could have made many more with the same resources as was used for the Fw200 and Junkers development projects.
I assume they would also make fewer BV138s and other sea planes as a result to balance resource usage.
https://en.wikipedia.org/wiki/Dornier_Do_26

Specifications -
Do 26V6
General characteristics

Crew: 4
Payload: 500 kg or 12 fully equipped troops (1,102 lb)
Length: 24.6 m (80 ft 5 in)
Wingspan: 30 m (98 ft 5 in)
Height: 6.85 m (22 ft 8 in)
Wing area: 120 m² (1,291.67 ft²)
Empty weight: 11,300 kg (24,912 lb)
Loaded weight: 22,500 kg (49,601 lb)
Powerplant: 4 × Junkers Jumo 205D Diesel, 656 kW (880 hp) each
Performance

Maximum speed: 324 km/h (175 kn, 201 mph)
Range: 7,100 km (3,834 nmi, 4,412 mi)
Armament

1 × 20 mm MG 151/20 cannon in a bow turret, 3 × aft-firing 7.92 mm (.312 in) MG 15 machine guns

Like the BV138 it could mount the Hohentwiel radar system when it became available in 1941, which I imagine cut into its range and payload a bit. I also imagine that without a payload the Do26's range was higher because it could carry more fuel.
The advantage is that it doesn't use Avgas, but rather diesel, which IIRC was far easier to make and more plentiful. It also didn't require an airfield, which was at a premium considering how many Luftwaffe planes were crammed into northern France in 1940-41.

What effect does this have on the Uboat war? I'd imagine it would mean more Wolf Packs form and inflict greater losses on convoys especially in the early 1940-41 period when that was still possible. I also think that because it wasn't a good bomber, the British wouldn't be forced to adopt CAM ships, so the Do26 has to contend with fewer threats to its tracking ability. By 1941 there would easily be over 100 in service and would have the Hohentwiel radar, would only be using non-essential fuel and engines with little if any rubber, plus could extend their range by meeting up with sea plane tenders to refuel and relaunch (the Do26 was catapult launch-able) saving fuel on takeoff.

For comparison:
https://en.wikipedia.org/wiki/Focke-Wulf_Fw_200#Specifications_.28Fw_200C-3.2FU4.29

Specifications
Fw 200C-3/U4 (late war model-post 1942)

General characteristics

Crew: 5
Capacity: 30 fully armed troops in transport configuration
Length: 23.45 m (76 ft 11 in)
Wingspan: 32.85 m (107 ft 9 in)
Height: 6.30 m (20 ft 8 in)
Wing area: 119.85 m² (1,290 ft²)
Empty weight: 17,005 kg (37,490 lb)
Max. takeoff weight: 24,520 kg (50,057 lb)
Powerplant: 4 × BMW/Bramo 323R-2 nine-cylinder single-row air-cooled radial engine, 895 kW (1,200hp) each
Performance

Maximum speed: 360 km/h (195 knots, 224 mph) at 4,800 m (15,750 ft)[14]
Cruise speed: 335 km/h (181 knots, 208 mph) at 4,000 m (13,100 ft) (Max cruise)
Range: 3,560 km (1,923 nmi, 2,212 mi)
Endurance: 14 hrs
Service ceiling: 6,000 m (19,700 ft)
Armament

Guns:
1 × 20 mm MG 151/20 cannon in forward gondola
4 × 13 mm MG 131 machine gun (dorsal and beam positions)
Bombs: Up to 2,100 kg (4,360 lb) of bombs

Notice too the weight difference of the empty aircraft. The Do26 is 6000kg lighter, meaning it requires less material to makes. In fact the Do 26 is only 66% of the weight of the Fw200, so is literally 2/3rds the cost in materials of the Fw200, implying that for the same investment in materials we get 3 Do26s for every 2 Fw200s. Not sure where the extra weight is coming from in the loaded weight of the Do 26 though; fuel maybe?

 

[Shortround6]

"The advantage is that it doesn't use Avgas, but rather diesel, which IIRC was far easier to make and more plentiful. It also didn't require an airfield, which was at a premium considering how many Luftwaffe planes were crammed into northern France in 1940-41."

It didn't need an airfield but it did a catapult to take-off at full loaded weight.

I doubt it would have changed anything very much, The Original design was intended to carry a small amount (1100-2200lbs?) of mail across the South Atlantic. For that job it may have been an excellent design. As a patrol bomber/reconplane it may have left something to be desired. Without more modifications view for some crew members is limited. The Range in Wikki is a bit unrealistic.

Figures from William Green (and he may be wrong, he was an some other things) Normal range 2980miles. Long range cruise speed 160mph.

MAX overload weight was 49,600lbs, Normal loaded weight was 46,217lbs ( and it may have needed the catapult even at that weight?)

The range of 2212 miles for the Condor seems to be the Normal range with 1773 imp gallons fuel. with 2190imp gallons range was supposed to be 2760 miles.

Both planes used almost identically sized wings. The Condor was not noted for structural strength (understatement).For a plane with almost the same sized wing to weigh about 1/3 less empty certainly raises some questions. Were the Dornier designers really that much better or was the DO 26 strength margin cut to the bone for that long distance, near record stetting range? How would it have stood up in service?

 

[tomo pauk]

We could get a hint about structural strength by looking at how goo/bad (historically) it was able to take the stresses of the 'landing' at the sea surface?

 

[Shortround6]

With only 6 built and 2 lost during the Norwegian campaign and the first having the lower powered engines and never modified to carry armament the remaining 3 aircraft didn't see enough service to get a good idea of what they could or could not do.

 

[davebender]

Do-26 max cruise speed = 193mph.
Fw-200 max cruise speed = 208mph.
Ju-290 max cruise speed = 224mph.
Do-217M (DB603 engines) max cruise speed = 248mph.

IMO Do-26 would be a step backward for long range recon.

Do-217 would be my first choice. In service during 1941 and cruise speed is relatively fast. Can carry a wide assortment of weapons including Hs.293 guided air to surface missile. Design a long range version similiar to what Junkers accomplished with Ju-88H and produce them in quantity for maritime patrol.

 

[wiking85]

Do-26 max cruise speed = 193mph.
Fw-200 max cruise speed = 208mph.
Ju-290 max cruise speed = 224mph.
Do-217M (DB603 engines) max cruise speed = 248mph.

IMO Do-26 would be a step backward for long range recon.

Do-217 would be my first choice. In service during 1941 and cruise speed is relatively fast. Can carry a wide assortment of weapons including Hs.293 guided air to surface missile. Design a long range version similiar to what Junkers accomplished with Ju-88H and produce them in quantity for maritime patrol.

What does the speed have to do with anything in 1940-41? Attacking shipping deep in the Atlantic was the job of the Uboat, not the recon aircraft; so they stay out of range and trail the convoy while vectoring in the limited number of Uboats. There are no aircraft that the Germans could have before 1942, long after it would matter, that had the range of the Do26. Why design something new for 1941 when Germany had something that didn't use Avgas and have much better range in 1939?

https://de.wikipedia.org/wiki/Dornier_Do_26
I'm not sure if I trust William Green's numbers on the Do 26's range Shortround. The German wikipedia link gives 20,000kg as the water launch weight and 21k kg as the catapult launch weight.

According to this:https://cs.wikipedia.org/wiki/Dornier_Do_26
Normal range for the militarized series was 3000 miles.
Dornier Do 26
Transport version was 6000km.
Dornier Do.26
Combat range 4800km (3000 miles) for the armed model.

 

[Shortround6]

Well, Green is saying 2980 miles, you have given at least two sources for 3000miles. I am not going to argue over 20 miles out of 3,000.

21,000kg is 46,297lb according to an on line calculator compared to Greens 46,217lbs Again I am not going to argue over 80lbs I doubt the actual planes were actually that close to each other in real life.

Basic point was that the figures in Wiki do not represent the true capabilities of the Do 26 in a Military setting.

 

[davebender]

Faster cruise speed allows you to search an area more quickly. If a convoy is found faster cruise speed allows bombers to arrive more quickly.

 

[wiking85]

Well, Green is saying 2980 miles, you have given at least two sources for 3000miles. I am not going to argue over 20 miles out of 3,000.

21,000kg is 46,297lb according to an on line calculator compared to Greens 46,217lbs Again I am not going to argue over 80lbs I doubt the actual planes were actually that close to each other in real life.

Basic point was that the figures in Wiki do not represent the true capabilities of the Do 26 in a Military setting.

Sorry, I read your post as saying the Do26's normal range was less than that. My mistake.
I do think that without the 500kg payload or with extra fuel that range would be extended.
Nevertheless the normal range of the Do26 is 300+ miles more than the extended range of the Fw200, which is pretty significant IMHO, especially when the extended range of the armed version can then be over 3000 miles with extra fuel instead of payload. Its still much better than the Fw200 or any comprable model until 1942-43. And it doesn't use Avgas, just diesel. If the Jumo 205D is improved further the range and speed can go up further.

The fuel consumption was super low for this engine too:
http://www.enginehistory.org/Diesels/CH4.pdf
https://de.wikipedia.org/wiki/Junkers_Jumo_205
According to the German link it was record settlingly fuel efficient.

Then there was the Jumo 207, which was basically a supercharged 205, which improved performance:
https://de.wikipedia.org/wiki/Junkers_Jumo_207
So the Do26 can be upgraded as needed in the future.

 

[wiking85]

Faster cruise speed allows you to search an area more quickly. If a convoy is found faster cruise speed allows bombers to arrive more quickly.

That's all well and good for bombers, which can still be used, but the slow and steady of the recon aircraft is more important in endurance work.
The Jumo 205/7 series was far more fuel efficient than anything else Germany or really anyone else had, so its ideally suited to the task. Convoys traveled very slowly at 4-7 knots for the slowest and 9-10 for the fastest:
World War 2: Convoy was the key to defeat of U-boats last time - Telegraph
At 193 mph cruise speed the Do26 was almost 17 times faster than the fastest convoy.
What was needed was endurance to search more ocean, which the added range over the contemporary aircraft of 1939-1942 gave the Do 26 an advantage. Not only that but it had a linger capability to track a convoy once picked up to home in Uboats, which is the entire point of the exercise; its not the task of the recon aircraft to attack, but to draw in the wolf packs, who were far more efficient and effective at sinking convoys especially early on, when they had only a single escort vessel. A wolf pack would really sink a whole lot of shipping in 1940-41, but very few were formed in this period because they couldn't get enough in position thanks to the lack of recon. Had they had a lingering recon aircraft homing them in the Uboats could have sunk and entire convoy in some cases. That never happened historically though it was certainly possible.

 

[davebender]

Build one that produces 1,200hp (i.e. similiar to early model Jumo 211 V12) and aircraft manufacturers will beat a path to your door. Otherwise fuel efficiency matters little.

 

[wiking85]

Build one that produces 1,200hp (i.e. similiar to early model Jumo 211 V12) and aircraft manufacturers will beat a path to your door. Otherwise fuel efficiency matters little.

https://de.wikipedia.org/wiki/Junkers_Jumo_207

Reasons for the Jumo 207D the hole was enlarged to 110 mm, thus a displacement of 18,250 cc and showed he made ​​Sun 1200 hp at an engine speed of 3000 rpm.

But that doesn't matter, because the point was having long range and endurance as I cited above. Later HP and speed can go up as needed by in 1939-1942 it doesn't matter as much, especially in 1940-41. Then all that is needed is numbers, range, fuel efficiency, and reliability, all of which the Do26 had/could have had in spades.

 

[GregP]

What about a Do.26 with DB engines instead of deisels?

It would be fatser at minimum. The four diesels had 600 Hp each. If they had four DB 601's at, say, 1100 HP each ... the power would almost double and the seed would be 255 mph ... if the airframe was capable of 255 mph in the first place.

 

[Shortround6]

Only the first one or two had 600hp engines, the others had 880hp engines.

 

[wiking85]

What about a Do.26 with DB engines instead of deisels?

It would be fatser at minimum. The four diesels had 600 Hp each. If they had four DB 601's at, say, 1100 HP each ... the power would almost double and the seed would be 255 mph ... if the airframe was capable of 255 mph in the first place.

Again, why is the speed necessary in 1940-41? They needed more endurance than the non-diesels provided. The diesels had the advantage of being extremely fuel efficient relative to the amount of fuel the frame carried AND was a non-strategic fuel in the way Avgas was. So in terms of endurance the DBs, besides being in massive shortage, were a step down in terms of range and fuel consumption.

 

[fnqvmuch]

just been reading about the catalinas locally; very useful given their generation and lack of speed
mining right up through the china sea to the home islands, 23+hour recce and SAR ...
steven

 

[wiking85]

just been reading about the catalinas locally; very useful given their generation and lack of speed
mining right up through the china sea to the home islands, 23+hour recce and SAR ...
steven

Less range, but a higher payload; the Do26 could have been the German Catalina easily, though mining would have to be the task of land based bombers like the He111 as historically happened, given the higher payload and numbers.

 

[davebender]

It sounds like the primary argument is for diesel engines due to increased fuel efficiency. So why not put tandem diesel engines on Do-217 airframe ILO DB603 V12 or BMW801 radial engine? Tandem engine pod should fit on Do-217 wing without too much difficulty. That gives you fuel sipping diesel engines on a relatively advanced bomber airframe.

 

[Juha]

Now what the Do 26 could do that Bv 138 couln't? 138 was chosen to be the main flying boat type, not a good idea to change the main type if there wasn't something concrete to gain.

Juha

 

[Juha]

On Jumo 207, IIRC it had reliability problems, even in 45. IIRC in those war-booty Bv 222s they still tended to easily catch fire.

Juha