WesWorld

[Note, in 1934 these proposals are on paper ONLY, the required engines are still on the drawing boards at BMW (and won't prove out to be successful anyway). If ordered, the first flights won't be until late 1935 at the earliest. Data on the BMW-139 is fairly sketchy, what I've been able to find says that it was a 1550 hp engine, used on the FW-190 prototypes and weighed several hundred pounds less than the BMW-801 that replaced it. So I've specced it at 1550 hp and 2015 pounds.]

First, the He-177: fitted with 15mm MG151s in a dorsal turret, the nose, and the rear of the ventral gondola, with 2 7.92mm MG 15s in beam positions.

Aircraft Type or Name:

Heinkel He-177

General Type:
Airplane = 1
Airship = 2
Orbiter = 3
1

Year of First Flight: 1936

Description

Conventional Aircraft
Monoplane
Conventional Fuselage


Characteristics:

Weight (maximum) 66,000 lbs
Weight (empty) 34,276 lbs

Length 71.5 ft
Wingspan 104 ft
Wing Area 1,440 sq ft
Sweep 2 degrees

Engines 4
BMW 139
Piston

1,550 hp
at 15,000 ft


Crew 7


Typical cost $0.189 million in 1939
Total number procured 2000


Performance:

Top Speed 269 kts = 309 mph
at 15,000 ft
Mach N/A

Operational Ceiling 25,500 ft

Range 2,200 nm = 2,533 miles
with 12,142 lbs payload
14,213

Climb 814 fpm

Cruise 205 kts = 236 mph
at 15,000 ft

Corner Speed 187 KIAS =
236 kts at 15,000 ft
Mach N/A
Turning Rate 12.3 deg/sec
Radius 3,706 ft



Internal Data:

Intake / Fan Diameter 12 ft

Bypass Ratio 100

Engine Weight 2015 lbs
Overall Efficiency 22.08 percent

Structural Factor 1.00

Number of Wings 1
Number of Fuselages 1

Limiting Airspeed 350 kts
Wing Ultimate g Load 6.00 g
Wing Taper 0.2
Wing Thickness at Root 2.8 ft

Tail / Canard Factor 0.4

Number of Nacelles 4
Length 12 ft
Diameter 5 ft
Fullness 0.3

Fuselage Diameter 6 ft
Fuselage Fullness 0.5

Pressurized Volume 0 percent
Cargo Decks 0

Cleanness 70 percent
Unstreamlined section 3.2 sq ft

User equipment 3,500 lbs

Next, the Ju-90S. A bit less heavily armed, with 1 15mm MG 151 in a dorsal turret, and 4 7.92mm MG 15s in the ventral gondola (fore and aft) and beam positions.

Aircraft Type or Name:

Junkers Ju-90S

General Type:
Airplane = 1
Airship = 2
Orbiter = 3
1

Year of First Flight: 1936

Description

Conventional Aircraft
Monoplane
Conventional Fuselage


Characteristics:

Weight (maximum) 66,000 lbs
Weight (empty) 36,037 lbs

Length 71.5 ft
Wingspan 115 ft
Wing Area 1,944 sq ft
Sweep 1 degrees

Engines 4
BMW 139
Piston

1,550 hp
at 15,000 ft


Crew 6


Typical cost $0.169 million in 1939
Total number procured 2000


Performance:

Top Speed 264 kts = 304 mph
at 15,000 ft
Mach N/A

Operational Ceiling 27,000 ft

Range 2,000 nm = 2,303 miles
with 12,269 lbs payload
14,124

Climb 831 fpm

Cruise 200 kts = 230 mph
at 15,000 ft

Corner Speed 164 KIAS =
206 kts at 15,000 ft
Mach N/A
Turning Rate 14.1 deg/sec
Radius 2,829 ft



Internal Data:

Intake / Fan Diameter 12 ft

Bypass Ratio 100

Engine Weight 2015 lbs
Overall Efficiency 22.08 percent

Structural Factor 0.90

Number of Wings 1
Number of Fuselages 1

Limiting Airspeed 280 kts
Wing Ultimate g Load 4.00 g
Wing Taper 0.2
Wing Thickness at Root 3.4 ft

Tail / Canard Factor 0.4

Number of Nacelles 4
Length 12 ft
Diameter 5 ft
Fullness 0.35

Fuselage Diameter 8 ft
Fuselage Fullness 0.5

Pressurized Volume 0 percent
Cargo Decks 0

Cleanness 67 percent
Unstreamlined section 3.2 sq ft

User equipment 3,200 lbs

The sources I found say that the 139 was a coupled 132 giving 1400hp. This seems a bit low considering that the 132 itself produced 850-960hp.

On the picture, essentially, yes. Nordmark has not requested dive bombing capability, so there's no reason to go crazy and provide it (with all the associated costs), so it's using standard engines.

On the BMW-139, it was more a two-row version of the BMW-132 than two coupled engines from what I can find, but yeah, the power output was fairly low considering the output of the BMW-132. I expect it could be that the development of the engine was cancelled so fast (because of cooling problems) that it never was worked up to it's full power. It's being used here because in WW 1934, it's the most powerful German engine currently on the drawing boards.

Gives us an idea how efficient engine coupling was. (Having discussion about italian engines in mind....)

Like I said, the -139 wasn't REALLY a coupled engine, it was more of a two-row version of the 132 rather than a pair of 132s driving a common shaft. I wouldn't make too much of the -139, it was the first two-row radial developed in Germany and as such there were difficulties.

Oh, found another plane the -139 was used on: the historical Ju-90 V6 (possibly the V5 as well, text is contradictory) prototypes for the Ju-90B military transport.

Quoted

Originally posted by HoOmAn
Gives us an idea how efficient engine coupling was. (Having discussion about italian engines in mind....)

Well if they're driving contra-props with no mechanical linkage then there are very few losses.

For an example of mechanical linkage driving one output shaft there is V-3420 which was two V-1710s couple onto a common crankcase. It produced 98% of the power of two single engines. This figure of 98% for mechanical efficiency is fairly typical in most applications.

Of course, long extension shafts running around and through the other engine add complications of their own. Not to mention effects on weight and balance, etc.

The V-3420 was one of the few coupled engines that worked pretty much the first time, most of the others had pretty long and painful development periods.