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2015-03-11

13:47












 

Notes

 

 

 

 

HEINKEL  He 177C  Griffin

 

The story which didn't happen ... outside Atlantic Air Combat

DRAFT - DOCUMENT STILL UNDER SCRUTINY...

 

See also : Data Sheet Articles Illustrations : He177B See Illustrations : He177C
 He177C.DataSheet  He177A Greif  He177B.Profile

 He177C.Profile
 He177B Greif  He177B.Top  He177C.Top
 He274A Greif  He177B.Bottom  He177C.Bottom
 He177B.Front (A,B,C)  He177C.Front
 He177B.Fuel Tanks  He177C.Fuel
 He177C.Bomb.Bay  He177C.Bomb.Bay
 He177B.Bomb.Bay - 1944  He177C.Bomb.Bay - 1948
 -  He177C.Bomb.Bay - 1959
     
     

Introduction
   
The Heinkel He177 Greif  had been the only real nazi heavy bomber during WWII, with a little over 1,000 manufactured during the war.  Among the various sequels of the design were the four engined He177B (often referred to as the He277), and the four engined high altitude He274 derivative produced by Farman in France, or the Atelier Aeronautique de Suresne as it would be called after the war, the aircraft itself being redesignated AAS-01 (two prototypes built, only one flown under French colors, after the war).

     

Prequel
   
Sources vary a little about the actual number of He177B assembled, but in the closing days of the war a full squadron of these high altitude pressurized bombers, accompanied by three Me323 transport aircrafts overloaded with technical documents about both the Heinkel bomber and its DB603S engines, fled to Sweden where they were immediately interned.   Not surprisingly, the Allies demanded these factory new aircrafts to be handed over to them, but to no avail.   In the end, having had the opportunity to seize and test fly a couple of He177A5, thanks the French Resistance, and considering the scores of airframes found resting on various airfields and the non imprssive results of the tests, the diplomatic harrassment was suspended in favour of an exchange of good will : would Sweden make one of these four engined bomber available, their technicians would be free to shop in these open air aircraft supermarkets.
 
It was somewhat a paradox because while Sweden had contemplated aquiring either Avro 694 or Boeing B-17G bombers, neither UK nor the US would sell them any.  Argentina and Brazil were however able to purchase packs of them...   In a way, Sweden did not really have the need for any heavy bombers, with access to modern aircraft technology being the real aim.  On the other hand, since 32 fully equipped airframes being handed for free...
  
From their visit in beaten Germany, Swedish engineers brought back a dozen of engineless He177A5 airframes and scores of DB603 engines and all sort of parts.   And with Volvo having had, after a long negociation during the war, the license to manufacture the DB605, a licence for the DB603A was easily granted.  Not that the Swedes intended to launch the production of the engine, but it gave them full access to the technology involved, including the TK11 turbo surpercharger, essential if they were to operate these aircrafts for some time which, after some debate, they decided to do.
 
First, the Swedish Air Force, informed about the various issues that plagued the type during the war, asked Saab to inspect the airframes and ensure they could be used safely.  These He177B2R4 as they were referred to by the manufacturer illustrated an interresting attempt to solve the many problems the Luftwaffe.  First, it propelled by four exhaust driven turbocharged DB603S, scheduled for the He274.  Much less troublesome than the 24 cylinder engines mounted on other variants, their combined power allowed some marked increase in MTOW.  They were associated with twin tail arrangement to enhance lateral control.  Second, the defensive armament was a mix of what had worked well, and what could have been mounted on the He277 "Amerika" bomber, with two quad MG161 turrets, one under the chin (controlled by the co-pilot) and one in the tail (pressurized like the main cockpit).  The manned mid-dorsal turret had been removed leaving only the remote controlled turret on top.   Hower, that general location had been replaced by a ventral turret remotely controlled from the gondola from which the single guns had naturally disappeared.  A most impressive set up indeed.   In order for the SwAF to operate these aircrafts in a durable manner, SAAB, Volvo and Ericsson identified several areas were improvements could be made; they were carried out in two steps : in 1946-1948 after the decision to add these bombers into SwAF inventory was made, and in 1956-1959 when these aircrafts were upgraded as "strategic bomber", an non-orthodox sequel, considering the time frame, of the adoption of nuclear weapons by both Sweden and Switzerland :

1946-1948 : He177C1 Griffin  or  B27A Grit

DB603S Engine Upgrade : Volvo suggested to rework the TK-11 turbo supercharger somewhat, to improve the power ouput at altitude, and fuel efficiency, bringing it from 0.474 lb/hp/hr down to 0.400 lb/hp/hr, a result similarly achieved by Wright with their R3500 turbo compound radial engine.  The performances of the DB603S and of the aircraft itself made the Swedes wonder why the German spent so much time redesigning the whole thing into the He274 as the He177B2R4 would fly almost as high as this French-built variant, and so would the revamped Swedish variant

Defensive weapons : as built, the He177B2R4 flown to Sweden had been equipped as follows :

Gun position
-
chin quad turret
dorsal remote twin turret
dorsal manned single turret
ventral remote twin turret
tail quad manned turret
Gun type
-
4  13.4mm MG131 guns
2  13.4mm MG131 guns
1  13.4mm MG131 gun
2  13.4mm MG131 guns
4  13.4mm MG131 guns
Ammunition
-
300 rpg
1000 rpg
1000 rpg
1000 rpg
300 rpg
Crew list
1: pilot
2: co-pilot/bombardier/gunner
3. navigator/gunner
4: gunner, in pressurized cell
5: gunner, laying in the gondola
6: gunner, in pressurized cell
Although other variants had seen 20mm MG151 replacing earlier small caliber guns, these four engine bombers had standardized on 13.4mm guns - a weaker but nevertheless impressive set up.
 
As in Swedish service these aircrafts were mainly intended for maritime patrol and/or high altitude flights over "hostile" territory, and considering the advent of jet fighters it was suggested to suppress all defensive armament short of the tail turret, where the MG131 guns would be replaced by locally produced AKAN44.  The SwAF only concede to the removal of the dorsal and ventral turrets, but retained both the tail and chin turrets, with the latter usually locked as fixed forward firing guns.  With Bofors perfectly able to supply ammunitions for the MG131, these were not replaced.

Internal Offensive weapons : the range of bombs used by Swedish Air Force differed somewhat from the one used by the Luftwaffe during the war, whith the heaviest type being the SW600 (600 kg) bomb.  This called for an adaptation of the bomb bays shackles, especially as the SwAF had adopted the 14"/30" lugs spacing system.  Numerous pairs of lugs were installed, allowing stores of various sizes to be loaded without having to disassemble/reassemble shackles as needed.
 
The bomb bay was more specifically adapted to carry as many 120kg SW120 bombs as possible in special clips lifted into the bay, and the medium sized 250kg SW250 bombs, the number of which was increased compared to the German arrangement for their similarly sized SC250.  A smaller number of either the 500kg SW500 or 600kg SW600 bombs could also be carried.
 
As time went, it was also found other weapons perfectly fitted in the bomb bay : British Mk11M3 depth charges, Mk30 ASW torpedoes and a liferaft containers.   While neither a dedicated ASW nor SAR aircraft, the He177C was neverthelss tasked for as "maritime patrol" and could bring in his load capacity if necessary.  The revised bomb bay would even swallow a pair of British ASS MkXVI surface torpedoes - while the use of such a weapon was never really contemplated, it was nevertheless tested.

Wing pylons : originally designed to carry the war time radio controlled FX1400 Fritz X glide bomb or Hs293 anti-shipping missile, the wing pylons (located between the engines on version) could carry whatever else the German had in their inventory, up to the massive 2,500 kg (5,507 lb) SC2500 demolition bomb.  While such extravagant items were absent from Swedish Air Force arsenal, these weapons carrying positions were adapted to Swedish standards to carry a single SW600 bomb or extra fuel.  However, the starboard pylon was eventually also wired to carry a podded radar.

Avionics : together with Ericsson, Saab suggested to take advantage of the removal of chin and aft gondola crew positions to install an enclosed chin mounted bombing/search radar.   However, this was too much of a rebuilt, and instead the SwAF opted for an off-the-shelf pod mounted radar (US made AN/APS-6)

Fuel System : All the aircrafts surrendered by the German crews had the "long bomb bay".  Maritime patrol, the basic scheduled tasking, requiring long endurance, Saab manufactured removable fuel cells which could be installed in either the forward (293 gal), central (293 gal) or aft (365 gal) bomb bays, thus allowing an extra 293, 365, 586, 658 or 951 gallons depending on the combination of extra fuel cells being carried.  While requiring careful handling, they weren't really more difficult to install and remove than a conventional underwing drop tank.
 
As already outlined, the existing underwing pylons were made able to carry extra fuel.  Various models in use with the SwAF were possible, but with the AN/APS-6 radar most usually carried on starboard, a 92 gal (110 US gal) drop tank was then carried under the port wing.
 
Compared to the most common He177A, the adoption of a single leg main landing gear, retracting backward in the inner engine nacelles, had left a huge empty space the Germans didn't left unused, as more fuel were carried in an extra four tanks, duplicating the inboard wing tanks.  Another specific aspect of this particular version of the Heinkel bomber

Reconnaissance Pack : the high speed and altitude (by 1945 standards) reached by these machines making them ideal high altitude photo reconnaissance aircrafts, a recce container was designed to be installed in the bomb bay, very much like an extra fuel tank.  It didn't call for the removal of the bomb bay doors as the middle ones were modifified to allow for the camera lenses.  This bomb bay doors modification was standard on all aircrafts.

Crew compartment : the removal of the dorsal and ventral firing position significantly reduced the crew, from 7 to 4.

1956-1958 : He177C2 Griffin  or  B27B Grit

The decision made by the Swedish government to develop a nuclear device had ripped their budget and left no funds available to develop an aircraft specifically designed to carry it.  It was expected that the size and weight of the weapon would shrink from around 3,000lb to probably a third of this value but the bulk of initial designs meant that only the antiquated Heinkel bomber could reasonably carry it.   As these war veterans seemed to have sustained a decade of use well, it was decided to have them undergo a major overhaul and improve them as far as they could :

Internal Offensive weapons : with the RbN nuclear bomb being scheduled for "less than 3,000lb", the ceiling of the bomb bays was adapted to carry an outsized weapon or a pair of them.  It didn't need any reinforcement as the bomber had initially designed to carry much heavier weapons in the 4,000lb-5,000lb class.   It was also the opportunity to make the aircraft able to carry the 2,000 M66 bombs which had been acquired from the US but without having the aicraft adapted to them, and the heavier 3,000lb M118 bombs.
 
While everyday a less likely weapon than the day before, the capacity to carry surface torpedoes was maintained as the American showed during the Korean War that it could be used against dams.  No reason to throw away an existing capacity.

Wing pylons : redesigned to the standards of the day, and with podded radar no longer a necessity, the original pair of pylons were rebuilt to accept NATO standards 14"/30" spaced lugs, and were stressed for up to 3,000 lb each.  They could carry extra fuel tanks, a single bomb (or a pair of SW250, in tandem), or the newly developped Rb4 anti-shipping missiles (outer pylons only).  Then, the bomber were also donned with a second pair of pylons, between the fuselage and the inner engine nacelles.   Like the original ones, they were stressed for 3,000lb and had the same capacity (fuel, single bomb or 2SW250), but could not carry the Rb4 missile.

Avionics : as time went, a more modern radar installation was felt a necessity, and the ancient ventral turret position was used to install an off-the-shelf Fairey Gannet Ecko ASV19 radar.  Besides its built-in surface search capacity, in support of the still present martime patrol role, it was tweeked for mapping/bombing purposes

Fuel System : an area were no improvements could be made, but for the adoption of larger underwing drop tanks.  While only a single small tank had been used until then (to aerdynamically balance the podded radar), the potential "strategic" mission required range to be extended to the maximum.  With the pylons brought to NATO standards, the Douglas designed streamlined 400 US gallons (334 gal) tank was favoured, once again an off-the-shelf item.  A strange coupling for sure but an efficient one, as far as extending range was concerned.

Crew compartment/Ejection seats : conscious that a strategic nuclear mission over hostile territory in an antiquated aircraft could, at the very least, be described as ... hasardous (suicidal ?), cockpit crews were donned with ejection seats.  These were of a simple type (basically the same as on the ancient J-21 fighters) but it was felt as an improvement in survivabilty, albeit a modest one.  The tail gunner hower still had to bail out in the traditional manner.

     

Aircraft Designation in the Swedish Air Force
   
Sweden having an aircraft designation of its own, these WW2 relics were not exceptions, although an ancient designation was used to cover these unexpected airframes :
The He 177 B2R4  was officially known as the B-27A Grit  but was often referred to as the He177C1 Griffin (in English !)
   When modified in the late 1950, they naturally were redesignated B-27B Grit and unofficially as the ... He177C2.
 
Swiss Air Force
 
The development of the Swedish nuclear arsenal was carried in co-operation with Switzerland.  Pending the availability of bomb small enough to be carried by a jet fighter, the SwAF loaned eight He177C2 airframes to the Swiss Air Force as from 1961.

     
Heinkel Greif Main Variants

  He177
  A1
He177
  A3
He177
  A5
He177
  B5
He274
  01
  He177
  C2









Production 130 170 826 6 2    
Crew: main 4 4 5 6 4   V
Crew: tail 1 1 1 1 -   V
Pressurized - - - - V   V
Radar - - - FuG217 ? -   ASV19
Engines 2xDB606 2xDB606 2xDB610 4xDB603A 4xDB603S   4xDB603S
Power each 2700 hp 2700 hp 2975 hp 1850 hp 1850 hp   1850 hp
Power total 5400 hp 5400 hp 5950 hp 7400 hp 7400 hp   7400 hp
Engine SFC ? ? ? 0.474 0.474   0.400
Power loading lb/hp/hr 12.37 12.17 11.86 13.25 11.32   11.68
Length 22.00 m 22.00 m 22.00 m 22.00 m 23.80 m   22.00 m
Span 31.44 m 31.44 m 31.44 m 31.44 m 44.20 m   31.44 m
Height 6.67 m 6.67 m 6.67 m 5.50 m 5.50 m   5.50 m
Weight empty 36376 lb 36597lb 37038 lb 48018 lb 46958 lb   47000 lb
Weight MTOW 66800 lb 65698lb 70548 lb 98105 lb 83776 lb   98100 lb
Wing area 100.00 m 100.00m 100.00 m 100.00 m 142.00 m   100.00 m
Wing loading lb/m 668 lb/m 657 lb/m 705 lb/m 981 lb/m 590 lb/m   691 lb/m
Speed cruise 220 kn 220kn 205 kn 248 kn 270 kn   270 kn
Speed max 260 kn 260kn 238 kn 308 kn 313 kn   310 kn
Speed stall     73 kn 73 kn 73 kn   73 kn
Ceilling 32800 ft 32800ft 26250 ft 49210 ft 46900 ft   49200 ft
Climb rate ? ? ? 780ft/min 780ft/min   780ft/min
Range naut.mile 3023 nm 3023 nm 3240 nm 3240 nm 1857 nm    
Guns/A1 nose upper 1000.rpg 1xMG81 1xMG81 1xMG81 - 1xMG131   -
Guns/A2 nose lower 300.rpg 1xMGFF 1xMGFF 1xMG151 -  
Guns/A2 chin turret 300.rpg 4xMG131 -   4xMG131
Guns/B1 dorsal turret fwd 1000.rpg 2xMG131 2xMG131 2xMG131 2xMG151 2xMG131   (2xMG131)
Guns/B2 dorsal turret aft 1000.rpg 1xMG131 1xMG131 1xMG131 1xMG151 -   (1xMG131)
Guns/C1 ventral gondola 1000.rpg 1xMG131 1xMG131 1xMG131 1xMG151   (1xMG131)
Guns/D1 ventral turret 1000.rpg 2xMG131  
Guns/H1 tail 300.rpg 1xMG131 1xMG131 1xMG151 4xMG131 -   4xMG131

Bomb Loads

Max

          Bomb   Loads Maximum  

Bomb bay SC50

110.lb

48

    5280.lb Bomb bay 40 SW120 [_264lb/@] 10560.lb

Bomb bay SC250

550.lb

12

    6600.lb Bomb bay 16 SW250 [_550lb/@] 8800.lb

Bomb bay SC500

1100.lb

6

    6600.lb Bomb bay 6 SW500 [1100lb/@] 6600.lb

Bomb bay SC1000

2200.lb

4

    8800.lb Bomb bay 6 SW600 [1322lb/@] 7932.lb

Bomb bay SC1800

3970.lb

2

    7940.lb Bomb bay 6 M66 [2000lb/@] 12000.lb

Bomb bay -

-

-

    - Bomb bay 6 M118 [3000lb/@] 18000.lb

Bomb bay -

-

-

    - Bomb bay 16 Mk11M3 [_319lb/@] 5104.lb

Bomb bay -

-

-

    - Bomb bay 4 Mk30 [_646lb/@] 2584.lb

Bomb bay -

-

-

    - Bomb bay 8 Liferaft [_100lb/@] 800.lb

Bomb bay -

-

-

    - Bomb bay 2 MkXVI [1400lb/@] 2800.lb

Bomb bay -

-

-

    - Bomb bay 2 RbN [1750lb/@] 3500.lb

Bomb bay -

-

-

    - Bomb bay 1 293gal [Empty:200lb] 2427.lb

Bomb bay -

-

-

    - Bomb bay 1 293gal [Empty:200lb] 2427.lb

Bomb bay -

-

-

    - Bomb bay 1 365gal [Empty:250lb] 3024.lb
Bombload maximum bomb bay     13227.lb       18000.lb

Wing Pylon 400US

2802.lb

2

    - Wing pylon 2 400US [2802lb/@] 5604.lb

Wing Pylon HS-293

2200.lb

2

    4400.lb Wing pylon 2 Rb04 [1322lb/@] 2644.lb

Wing Pylon SC50

110.lb

2

    - Wing pylon 2 SW120 [_264lb/@] 528.lb

Wing Pylon SC250

550.lb

2

    4400.lb Wing pylon 2 SW250 [_550lb/@] 1100.lb

Wing Pylon SC500

1100.lb

2

    4400.lb Wing pylon 2 SW500 [1100lb/@] 2200.lb

Wing Pylon SC1000

2200.lb

2

    4400.lb Wing pylon 2 SW600 [1322lb/@] 2644.lb

Wing Pylon SC1200

2460.lb

2

    4920.lb Wing pylon 2 M66 [2000lb/@] 4000.lb

Wing Pylon SC1400

3085.lb

2

    6170.lb Wing pylon 2 M118 [3000lb/@] 6000.lb

Wing Pylon SC1600

3525.lb

2

    7050.lb Wing pylon 2 Mk11M3 [_319lb/@] 638.lb

Wing Pylon SC1800

3970.lb

2

    7940.lb Wing pylon 2 Mk30 [_646lb/@] 1292.lb

Wing Pylon SC2000

4295.lb

2

    8590.lb Wing pylon 2 MkXVI [1400lb/@] 2800.lb

Wing Pylon SC2500

5285.lb

2

    10570.lb Wing pylon 2 RbN [1750lb/@] 3500.lb
Bombload maximum wing pylons     10570.lb       6000.lb
Fuel tank 01 Fuselage fwd     334.gal 334.gal   334.gal 2538.lb
Fuel tank 02 wing port inner     136.gal 136.gal   136.gal 1034.lb
Fuel tank 03 wing stbd inner     136.gal 136.gal   136.gal 1034.lb
Fuel tank 04 fuselage fwd     330.gal 330.gal   330.gal 2508.lb
Fuel tank 05 fuselage aft     330.gal 330.gal   330.gal 2508.lb
Fuel tank 06 fuselage aff     334.gal 334.gal   334.gal 2538.lb
Fuel tank 07 wing port outer     246.gal 246.gal   246.gal 1870.lb
Fuel tank 08 wing sbd outer     246.gal 246.gal   246.gal 1870.lb
Fuel tank 09 wing port inner fwd     - 136.gal   136.gal 1034.lb
Fuel tank 10 wing stbd inner fwd     - 136.gal   136.gal 1034.lb
Fuel tank 11 wing port outer fwd     - 246.gal   246.gal 1870.lb
Fuel tank 12 wing sbd outer fwd     - 246.gal   246.gal 1870.lb
Fuel tank 00 bomb bay fwd   Extra value:

425.gal

425.gal Extra fuel cell 293.gal 2427.lb
Fuel tank 00 bomb bay ctrl   Extra value:

425.gal

425.gal Extra fuel cell 293.gal 2427.lb
Fuel tank 00 bomb bay aft    

-

  Extra fuel cell 365.gal 3024.lb
Fuel Total Internal Full Standard     2092.gal 2856.gal 10130 litres 2856.gal 21706.lb
Fuel Total Internal Extra     850.gal 850.gal   951.gal 7228.lb
Fuel Total External Extra 4x400 USgal    

-

    1336.gal 10154.lb
Fuel Total Maximum     2942.gal 3706.gal   4475.gal  









Weight & Loads Summary     He177A5 He177B5 He274A1   He177C2
Weight empty     37038 lb 48018 lb 46958 lb   47000 lb
Fuel Total Internal Full Standard     15900.lb 21706.lb 16958.lb   21700.lb
Bombload maximum bomb bay   in practice: 8800.lb 8800.lb 8800.lb in practice: 18000.lb
Bombload maximum wing pylons   in practice: 10570.lb 10570.lb - in practice: 6000.lb
    72308.lb 89094.lb 72716.lb   92700.lb
               
Weight MTOW (historical)     70548 lb 98105.lb 83776.lb   98100 lb









Weight & Loads Strategic             He177C2
Weight empty             47000 lb
Fuel Total Internal Full Standard 2856.gal           21700.lb
Fuel tank 00 Bomb bay aft 365.gal           3024.lb
Fuel Total External Extra 4x400 USgal 1336 gal         2802.lb 11220.lb
Bombload : 2RbN         - 1700.lb 3400.lb
            86344.lb
               
Weight MTOW (historical)             98100 lb
 

___________

 

 

TEMPORARY BACKBROUND DATA
48  50kg ( 110lb) bombs (5291lb total)
 12500kg (5511lb) bomb  (5511lb total)
12 250kg ( 551lb) bombs (6613lb total)
 6 500kg (1102lb) bombs (6613lb total)
 21800kg (3968lb) bombs (7936lb total)
 21800kg (3968lb) bombs + 2LMA III mines (10141 lb total)
10 500kg (1102lb) bombs (11023lb total)
 21000kg (2204lb) bombs + 21800kg (3968 lb) bombs (12345lb total)
 61000kg (2,204 lb) bombs (6,000 kg/13,227 lb total)
 2FX 1400 Fritz X + 1 FX 1400 Fritz X under the wings and fuselage
 2Hs 293 or 294 + 1 Hs 293 or 294 under the wings and fuselage
 2500 kg (1,102 lb) bombs internally + 2 Hs 293 under the wings
 2LT 50 torpedoes under the wing
 
http://www.warbirdsresourcegroup.org/LRG/bombs.html
PC1000RS armour-piercing boosted len 2.20m
PC1000 armour-piercing len 2.17m
SB1000 armour-piercing len 2.64m
SD1000 semi-armour-piercing and fragmentation len unkown
SC1000C general purpose len 2.78m
SC1000L general purpose len 2.53m
SC1000L2 general purpose len 2.78m
 
Bombs Weight Body Length Warhead Hs293   Hs294   Hs295  
SC0050 110.lb 7.8" 43.2" 55.lb Type anti-ship missile Type anti-ship missile Type anti-ship missile
SC0250 550.lb 14.5" 63.6" 300.lb Weight 1000kg Weight 2.2 tons Weight 2100kg
SC0500 1100.lb 18.5" 79.2" 600.lb Length 3.14 Length 6.1 m (20.08 ft) Length 5.44m
SC1000 2200.lb 25.7" 110.4" 1170.lb Span 3.58 Span 4 m (13.2 ft) Span  
SC1200 2460lb 75.0" 109.5" 1390lb Body 480mm Body 620mm Body 0.553
PC1400         Rocket 1300 lbf/10sec Rocket 2x590kgf Engine 2x1700 kgf
PC1600         Warhead 295kg Warhead 456kg Warhead 580kg
SC1800 3970.lb 26.0" 138.0" 3300.lb Speed max 960km/h Speed max 860 km/h Speed max 860km/h
SC2000 4295lb 26.0" 136.5" 2148lb Range2 16km Range   Range  
SC2500 5286lb 32.0" 154.3" ?? Note Mod SC500 Note   Note