Estimated performance of a He177B with Jumo 211 engines

[wiking85]

Does anyone have any idea what sort of performance a four engined He177 would have with Jumo 211F engines? Or DB601E engines? I'm assuming a 1942 operational date.
Junkers Jumo 211 - Wikipedia, the free encyclopedia

Engine model Power in PS Power in hp Power in kW power at rpm
F,L,M,R 1,340 1,322 986 2,600

Daimler-Benz DB 601 - Wikipedia, the free encyclopedia

DB 601 E
Up to 1,350 PS (992.9 kW; 1,331.5 hp) at sea-level with 2,700 rpm, up to 1,320 PS (970.9 kW; 1,301.9 hp) with 2.700 rpm at 4,800 m (15,700 ft) altitude, B4 fuel
Up to 1,450 PS (1,066.5 kW; 1,430.2 hp) at 2,100 m (6,900 ft) altitude with 2,700 rpm

I'm assuming the weight of each is around 750kgs.

 

[tomo pauk]

M. Griehl notes 480 km/h for the DB-606 powered He-177. DB-606 was basically a twinned DB-601E. If we assume some loss due to single engines installed in this case, it will be maybe 460-470 km/h? That should be on 'Kampfleistung' (30 min regime, 2 x 2400 PS at 4.9 km).
Heinkel was giving 550 km/h for the DB-610 powered versions (610 would be a twinned 605A), on 'Kampfleistung' (30 min regime, 2 x 2500 PS). The aircraft description sheet does not mention 'Notleistung' (5 min regime, that should be 2 x 2710 PS), probably was not allowed? Griehl notes 520-540 for DB-610 powered versions (4 of them).

The Jumo 211 F will make some 10% less power than the DB-601E, the Heinkel with 4 such engines will be good for maybe 450 km/h? The 211 J is thereabout with the DB-601E in power, though - 1180 PS at 4.9 km on Kampfleistung.

 

[davebender]

He-177B with four Jumo 211 engines has about the same total engine power as Lancaster Bomber. I would expect roughly similar performance.

 

[wiking85]

He-177B with four Jumo 211 engines has about the same total engine power as Lancaster Bomber. I would expect roughly similar performance.

They had some pretty different aerodynamics.

M. Griehl notes 480 km/h for the DB-606 powered He-177. DB-606 was basically a twinned DB-601E. If we assume some loss due to single engines installed in this case, it will be maybe 460-470 km/h? That should be on 'Kampfleistung' (30 min regime, 2 x 2400 PS at 4.9 km).
Heinkel was giving 550 km/h for the DB-610 powered versions (610 would be a twinned 605A), on 'Kampfleistung' (30 min regime, 2 x 2500 PS). The aircraft description sheet does not mention 'Notleistung' (5 min regime, that should be 2 x 2710 PS), probably was not allowed? Griehl notes 520-540 for DB-610 powered versions (4 of them).

The Jumo 211 F will make some 10% less power than the DB-601E, the Heinkel with 4 such engines will be good for maybe 450 km/h? The 211 J is thereabout with the DB-601E in power, though - 1180 PS at 4.9 km on Kampfleistung.

Why would the 211F give less power than the 601E? They had the same startleistung.

Also I've read the twin engine saved 3-4% drag over the four engine version. Not sure what the four engine wing would have weighed against the twin engine or how the twin tail layout vs. the single fin would affect aerodynamics.

Here are the numbers I found for the 606 and 610:

DB 606 A/B
Two DB 601 F or G coupled to work on a single propeller shaft for use in early Heinkel He 177As - 2,700 PS (1,986 kW) at sea level with a mirror-imaged starboard component engine supercharger

DB 610
Two DB 605 "coupled" (geared together) as a "power system" (71.53L / 4364.8in3), to work on a single propeller shaft for use in Heinkel He 177, up to 2950 PS (2,909 hp) for take off, 2788 PS (2,750 hp) at 2,100 m.[6] Mirror-imaged starboard component engine supercharger.

 

[tomo pauk]

...
Why would the 211F give less power than the 601E? They had the same startleistung.

Startleistung (take off power) is just one narrow (but many times important) part of power curve, and in many more cases than not actually muddles the water re. engine power at altitude.
Supercharger capability and supercharger gearing are main determinants of the power vs. altitude. Some engines sacrificed power at altitude in order to gain more power at low level, or vice versa. We can compare the BMW 801C and R-2800 'A' - BMW has a comparable power at altitude, however the R-2800 is much better at mid and low altitudes.
I especially loath when someone (Wikipedia mostly) just says 'Merlin of 1030 HP', or 'DB-601A of 1175 PS' - just complicates the matters for someone after a real information.

Here are the numbers I found for the 606 and 610:

Some data for the DB 610 from Heinkel's brochure on the He-177A-3:

 

[Denniss]

Jumo 211 take-off power was just for 1 minute and low alt, similar to the 1-min boost in the 601A (mechanische Überfettung, extra-rich mixture). The 601E could hold it for longer time (in theory).
At alt the 211F had about 100-150PS less the 601E (starting to lose above 1.9 km (1st gear rated alt)) + the smoother powercuve of the 601E vs the bump during gear switch in the 211.

 

[wiking85]

Startleistung (take off power) is just one narrow (but many times important) part of power curve, and in many more cases than not actually muddles the water re. engine power at altitude.
Supercharger capability and supercharger gearing are main determinants of the power vs. altitude. Some engines sacrificed power at altitude in order to gain more power at low level, or vice versa. We can compare the BMW 801C and R-2800 'A' - BMW has a comparable power at altitude, however the R-2800 is much better at mid and low altitudes.
I especially loath when someone (Wikipedia mostly) just says 'Merlin of 1030 HP', or 'DB-601A of 1175 PS' - just complicates the matters for someone after a real information.



Some data for the DB 610 from Heinkel's brochure on the He-177A-3:

View attachment 288181

Do you have the same information about the DB601/5 and Jumo 211 models from early 1942?

 

[tomo pauk]

Plenty of engine data is posted here.

Thick black - Jumo 211F; green - DB 601E; red - Jumo 211J; all for 30 min rating. Please note the 'Startleistung' (take off power) for the Jumos - 1340 and 1420 PS for the 211F and 211J respectively. The Startleistung for the 601E was 1350 PS (from Dec 1941/Jan 42 on). Jumo 211J, aftercooled variant of the 211F was also available from 1942.

 

[GregP]

The He 277 had four engines of 1,973 HP each for a total of 7892 HP and went 354 mph. I KNOW it didn't get that HP at best altitude, but we have to start somewhere.

If they installed four Jumo 211s of 1322 HP each we have 5288 HP. If I assume a decrease in drag of 10% for the liquid-cooled, smaller engines, we'd get 321 mph on the Jumos. If we go with the four 1450 HP DBs and the same decrease in drag, I get 331 mph. If there was no decrease in dreag, the speeds would drop by some 11 mph or so.

Again, this is a first-order approximation, but I think the real crews would have preferred the 4-engine units to what they got, and if it had proven successful, who knows ... they might have built and deployed more of them.

 

[wiking85]

The He 277 had four engines of 1,973 HP each for a total of 7892 HP and went 354 mph. I KNOW it didn't get that HP at best altitude, but we have to start somewhere.

If they installed four Jumo 211s of 1322 HP each we have 5288 HP. If I assume a decrease in drag of 10% for the liquid-cooled, smaller engines, we'd get 321 mph on the Jumos. If we go with the four 1450 HP DBs and the same decrease in drag, I get 331 mph. If there was no decrease in dreag, the speeds would drop by some 11 mph or so.

Again, this is a first-order approximation, but I think the real crews would have preferred the 4-engine units to what they got, and if it had proven successful, who knows ... they might have built and deployed more of them.

The He277 was significantly heavier than the He177 by 5 tons; part of that was the longer wings and fuselage for rebalancing, but was also the extra fuel tanks, as it was the Atlantic Bomber entry by Heinkel, so was different than what the He177B would have been; also the BMW 801 engines were significantly heavier and probably required stronger wings than the Jumos or Daimlers would have. The drag would have been roughly the same, but for the engines as you point out. I think maybe deleting 2-3 tons would be warranted here compared to the four engined He177 due to lighter engines, less fuel tanks, and lighter wings.

 

[kool kitty89]

The He277 was significantly heavier than the He177 by 5 tons; part of that was the longer wings and fuselage for rebalancing, but was also the extra fuel tanks, as it was the Atlantic Bomber entry by Heinkel, so was different than what the He177B would have been; also the BMW 801 engines were significantly heavier and probably required stronger wings than the Jumos or Daimlers would have. The drag would have been roughly the same, but for the engines as you point out. I think maybe deleting 2-3 tons would be warranted here compared to the four engined He177 due to lighter engines, less fuel tanks, and lighter wings.

With the dive bombing requirement omitted, a 4-engine He 177 very well may have been lighter than the existing He 177A models too.

 

[wiking85]

With the dive bombing requirement omitted, a 4-engine He 177 very well may have been lighter than the existing He 177A models too.

probably not with longer, heavier wings and a lengthening of the fuselage to compensate.

 

[Koopernic]

The first He 177B that flew with 4 separate engines was essentially based on the same airframe as the He 177A3 or A5 and had about the same 34.44 metre wing span.

The He 177 models go as follows
1 He 177A1 had a 34.44 meter wing span with DB606A/B engines. These were essentially paired DB601 engines geared so as to be contra rotating.
The He 177A1 was not service ready and had been rushed into service, the Luftwaffe was fearful of further engine problems stayed with the DB606 engines on the first batch of He 177A3.
2 He 177A3 had the same dimensions but its tail was lengthened to allow the engines to be moved forward (thus disturbing the centre of gravity) so as to improve the engine installation and cooling.
the engines of early He 177A3 were also DB606A/B which were paired DB601E as used on the Me 109F4.
The engines of the latter He 177A3 were DB610A/B which were essentially paired DB605A as was used on the Me 109G1.

The He 177A5 was similar to the He 177A3 with DB610, supposedly the problems were solved in early 1944 as engine MTBO became about 220 hours.

The next generation was to be the He 177A7 which had the wing span increased from 34.44m to 40m and used DB613A/b engines which were the much bigger paired DB603.

The He 177A7 wing had been designed from the outset to be configurable as paired or 4 independent engines. The 4 independent engine version was known as the He 277B7.

Hence we are dealing with two versions of the He 277, those with or without the He 177A7 derived wing and fuselage. No impediment was placed in the way of developing the He 277 as a 4 engine aircraft, they were sick of the problems.

The He 177B that first flew had the 34.4m wing span, the latter He 277 that was completed, flown and then scrapped at Vienna I think the larger wing, not sure.

One problem was that the more powerful engines created more torque so more tail area was required, hence the emergence of twin tails. This may just have been a problem of the engines not being available as counter rotating types.

*********

With 4 separate engines I doubt there would have been much if any loss in speed. The main advantage of two big engines over 4 equally distributed ones is structural and aero elastic as its better to have the mass of the engine nearer the fueselage. Obviously aero-elasticity is an serious issue in dive bombing but that requirement had been quietly dropped long ago.

Im going to say that the speed would be the same, there is no advantage in frontal area of paired over individual DB601 and the slight increase in weight would not impair speed by much.

So instead of 295-298mph I'd say 295mph.

The Jumo 211J at 1420 hp is actually offering more Take Off power than the DB601E and even the DB605A at 1.3 ata. So I'm going to say the speed with Jumo 211J would be a the same.

The 2500hp Jumo 222A2/B2 the 3000hp Jumo c/d or 3500hp jumo 222g/h might have had a speed advantage due to their genuine reduction in frontal area, size and weight.

If the DB605 came along its superior power at altitude would make a significant difference, it would be much faster as He 177A5 managed around 315mph clean but with 7700kg bombs.

The He 177 was fairly clean due to the effort that was taken with low drag turrets.

Obviously the Luftwaffe could have had a trouble free aircraft if the He 177A1 had of been introduced with individual DB601AA engines, which would give away to DB601E in late 1941 and then the heavier and equally dimensioned DB605A from mid 1942.

An alternative route suggests the Jumo 211F (1350hp) in 1941 and Jumo 211J (1420hp) in mid 1942.

Non of the above would require any reeingeering of the airframe. I doubt even the BMW801 would require reengineering.

In early 1942 the BMW801 becomes a possibility offering 1560hp on B4 fuel or 1700 on C3 rising to 2050 take-off by early 1944.

In 1943 the big 920kg DB603 become available with 1750hp. The weight and power might require some strengthening and fuselage lengthening but historically this was done with the He 177A5 anyway.

An effective 4 engine He 177 in 1942 would have:
1 provided an effective reconnaissance for the German Navy.
2 allowed 280 Fw 200 Condors to be used exclusively as transports.
3 Fw 200 condors using the Lotfe 7 computing bombsight didn't have much problem hitting merchant ships from 12000-14000ft. I count 33% hit rates in 3 attacks releasing a stick of 2 or 4 bombs each time. At this altitude the AA defences of escorts such as frigates and sloops was ineffective and only a destroyer had the fire control to even remotely deter the aircraft and in reality a cruiser was needed. Warships could manoeuvre to avoid the bombs but supply ships had little hope.
4 Common escort carrier aircraft such as FM-2/martlet/Wildcat and Sea Hurricane would be of greatly reduced effectiveness due to their small speed margin and the armoured 20mm gun in the tail. The Beaufighter would be reduced effectiveness though the Mosquito would remain deadly.

If a BMW801 engine version can be deployed by the end of 1942 the Wildcat/Marltet and Beaufighter can be considered ineffective.

 

[GregP]

The He 177 was a neat idea that died in practice. The Luftwaffe killed it's chance at a bomber with the dive-bombing requirement and never recovered.

They had the Me 264, which needed some "fixing", the He 277, and the Ju 290 / 390 as real, live aircraft and never DID get many of any into the fray. They only built 3 Me 264s.

So, any operational larger bomber would have been a vast improvement over what they really had in the actual war.

I think they could have built the Ju 488 and would have done very well, but not with the very troublesome Jumo 222 ... they needed to size it for four RELIABLE engines that were available for use in a real production bomber, not make it all they ever wanted, but only with a troublesome prototype engine. Had it been so-sized, the payload and speed would have dropped a bit, but it would have been flying instead of being a pipe dream.