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ROOLS-ROYCE MERLIN
Engine Maintenance Manual
Derby, England, 1946
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| TYPE OF ENGINE |
Supercharged, geared, pressure-liquid cooled, V-engine,
fitted with two-stage, two speed centrifugal supercharger
with intercooler. |
| NUMBER OF CICLINDERS |
12 |
| CILINDER ARRAGEMENT |
Two banks of six cylinderseach, with an included angle of 60° |
| BORE AND STROKE |
5.4 ins. X 6.0 ins |
| SWEPT VOLUME |
1,648 cu. ins. |
| COMPRESSION RATIO |
6.0 to 1. |
| SUPERCHARGER |
|
| Type |
Two-stage, two-speed |
| Gear Ratios |
Merlin 66, 67, 85, 100,
104, 130, & 131 |
5.79 to 1 & 7.06 to 1 |
|
Merlin 61, 67, 72, 73, 76, 77,
73, 76, 113 & 114 |
6.39 to 1 & 8.03 to 1 |
| PROPELLER REDUCTION GEAR |
|
| Type |
Single spur |
| Ratio |
Merlin 61, 67, 72, 73, 76, 77
85, 100, 104, 113, 114 & 130 |
.420 to 1 |
|
Merlin 66, 70, & 71
Merlin 131 |
.477 to 1
.422 to 1 |
| DIRECTION OF ROTATION |
|
| Propeller shaft |
Right-hand (Merlin 131 only). |
| Crankshaft |
Left-hand. |
| CYLINDER NUMBERING |
1A, 2A, 3A, 4A, 5A, 6A.
1B, 2B, 3B, 4B, 5B. 6B. |
| WEIGHT OF ENGINE, NETT DRY |
Merlin 61
Merlin 66, 67, 70, 71, 72, 73, 76 & 77
Merlin 85
Merlin 100, 104, 130 & 131
Merlin 113
Merlin 114 |
1,640 lbs. 21 Tolerance
1,645 lbs. 21 Tolerance
1,665 lbs. 21 Tolerance
1,720 lbs. 21 Tolerance
1,650 lbs. 21 Tolerance
1,654 lbs. 21 Tolerance |
PERFORMANCE
International Power Rating. |
Low Gear
M.S. |
High Gear
F.S. |
Merlin 61, 72 & 73
Merlin 66, 67 & 85
Merlin 70, 71, 76 & 77
Merlin 100, 104, 130 & 131
Merlin 113 & 114 |
1,400 b.h.p. 12,000 ft
1,400 b.h.p. 9,250 ft
1,375 b.h.p. 13,500 ft
1,410 b.h.p. 10,000 ft
1,380 b.h.p. 15,750 ft |
1,250 b.h.p. 24,000 ft
1,310 b.h.p. 19,000 ft
1,255 b.h.p. 25,250 ft
1,315 b.h.p. 21,500 ft
1,200 b.h.p. 29,750 ft |
These powers are obtained at 12 lb. per sq. in boost pressure and 2,850 r.p.m.
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| IGNITION |
|
| Firing order |
1A, 6B, 4A, 3B, 2A, 5B. |
|
6A, 1B, 3A, 4B, 5A, 2B. |
| Magnetos |
Two. |
| Type |
B.T.H. C6SE-12 S, 12S 1 or 12 S 2, or ROTAX NSE 12-4 or 6. |
| Contact breaker gap |
0.012 in. ± 0.001 in. |
| Sparking plug gap |
0.018 in. - 0.021 in. |
| TIMING |
|
| Fully advanced |
Port 45° before T.D.C.
Stbd. 38° before T.D.C. |
| OIL |
|
| Consumption at max. cruising |
6 to 20 pints per hour. |
| Minimum main oil pressure in flight |
min 30 normal 40 lb. per sq. at 2,200 r.p.m. & 60°C/90°C. |
| CARBURATION |
|
| Carburettor |
Merlin 61, 72 & 73
Merlin 66, 67, 70, 71, 76, 77 & 85
Merlin Merlin 100, 104, 113,
114, 130 & 131 |
S.U. Anti-G. Float Type.
R.R. Bendix SD 44 I.D.E.
S.U. Single-point, fuel
injection pump. |
| Fuel |
100 octane |
| Max. fuel demand |
Merlin 61
Merlin 72 & 73
Merlin 66, 67, 70, 71, 76, 77 & 85
Merlin Merlin 100, 104, 113, 114, 130 & 131 |
135 galls. per hour.
154 galls. per hour.
153 galls. per hour.
205 galls. per hour. |
| Pump pressure to carburettor |
Merlin 61,72 & 73
Merlin 66, 67, 70, 71, 76, 77 & 85 |
9 lb. per sq. in. ± 1 lb.
14 lb. per sq. in. ± 1 lb. |
| Fuel pressure to injector pump |
Merlin 104, 113,114, 130 & 131 |
7 lb. per sq. in. ± 3 lb. per sq. in.
- booster pump pressure |
| VALVES |
|
| Type |
Tulip type poppet valves, exhaust valve sodium cooled. |
| VALVE TIMING |
|
| With 0.014 in cam clearance |
|
| Early type camshaft (Pre-mod. 987) |
Inlet opens
Inlet closes
Exhst.opens
Exhst. closes |
31 deg. before T.D.C.
52 deg. after B.D.C.
72 deg. before B.D.C.
12 deg. after T.D.C. |
| Parabolic type camshaft (POst-mod 987) |
Inlet opens
Inlet closes
Exhst.opens
Exhst. closes |
38 deg. before T.D.C.
72 deg. after B.D.C.
78 deg. before B.D.C.
32 deg. after T.D.C. |
| Running cam clearance (both types of camshaft) |
Set 0.009 in. Allow to fall to 0.006 in. before resetting (inlet).
Set 0.015 in. Allow to fall to 0.012 in. before resetting (exhst.). |
| ENGINE COOLANT |
|
| Type |
Pressure liquid (70% water - 30% ethylene glycol to Spec. DTD 344A). |
| System |
Merlin 61, 66,70, 71 & 100
Merlin 67, 72, 73, 76, 77
104, 113, 114, 130 & 131 |
Normal flow
Reverse flow
. |
| INTERCOOLER COOLANT |
|
| Type |
Pressure liquid (70% water - 30% ethylene glycol to Spec. DTD 344A). |
| STARTING SYSTEM |
Hand or electric turning gear. |
| PROPELLER |
Rotol or De-Havilland constant speed type. |
This foolowing accessories may be fitted to engines not employing an accessory gearbox.
| Accessory |
Speed Ratio
(relative to crankshaft) |
Direction of Rotation
(looking on driving
spindle of accessory) |
| Constant-speed governor unit |
0.828 |
Clockwise |
| Vacuum pump |
0.828 |
Clockwise |
| *Electric generator |
1.953 |
Anty-clockwise |
| **Electric generator |
2.100 |
Anty-clockwise |
| ***Electric generator |
2.110 |
Clockwise |
| Starter motor - |
|
| Epacyclic type |
91.560 |
Clockwise |
| Spar reduction type |
86.500 |
Clockwise |
| Air compressor (camshaft) |
6.500 |
Clockwise |
| Hydraulic pump (camshaft) |
1.000 |
Clockwise |
| R.P.M. indicator drive (camshaft) |
0.250 |
Clockwise |
| Hydraulic pump (crankcase) - |
|
| Vertical drive |
0.810 |
Clockwise |
| ****Cabin supercharger |
0.913 |
Anty-clockwise |
| When the Rotel universal gearbox is fitted, the direction of rotation for the accessories will depend upon the particular aircraft reguirements. The gear ratios, however, relative to crankshaft, will be as follows: -
|
| Electric generator |
1.826 |
The accessories listed below will, in all cases,
be mounted on the engine itself, and run at
the speeds quoted under "Accessories": -
Constant-speed governor unit, Starter motor
and Engine-speed indicator drive |
| Hydraulic pump |
|
| Low-pressure air compressor |
0.913 |
| Vacuum pump |
|
| High-pressure air compressor |
0.456 |
* Merlin 61, 66, 67, 70, 71, 72, 73, 76, 77, 85, 100, 104, 113 & 114.
** Merlin 130.
*** Merlin 131.
**** Merlin 61, 71, 73, 77, 104 & 114.
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