Merlin XX
Rolls-Royce Merlin XX No26071
 
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Bristol Beaufighter IIf, Serial No R2335




Beaufighter R2335 was fitted with Merlin XX engines 25985 and 26071, the latter being the engine I now run. The aircraft served during 1941 with the Fighter Interception Unit, based at Ford Airfield, near Chichester, West Sussex. It was employed as a radar equipment test-bed, in particular AI, or Airborne Interception (seeing other planes at night).

On the night of 3rd September 1941, the pilot, Flying Officer Donald lake discovered that the undercarriage would not lock in the lowered position. The decision was taken to shake the undercarriage down by means of aerobatic manouvres at about 8000ft.

The FIU had many excellent pilots, noted for their night-fighting abilities, such as the legendary John "Cats Eyes" Cunningham.

Despite this, the aeroplane became out of control, entering an uncontrolled dive from which the crew had no means of escape, and crashed 4 miles west of the airfield into a disused canal bed.

The site was excavated during 1978, the engines and propellers being recovered, and much of the remaining wreckage scrapped.

After a restoration project lasting some 3000 hours, Merlin 26071 ran once again early in 2000, a living memorial to the three airmen listed below, and all who lost their lives in this conflict.

 

   Roll Of Honour

Pilot             Flying Officer Donald Millar Lake          Age 20

Navigator      Flight Sergeant Frank Edward Greaney  Age 20

Technician     Flight Sergeant John Edward Bignell     Age 23

 

Flying Officer Lake was by no means inexperienced, having a total of 668 flying hours, 192 of which were on Beaufighter Mk IIF aircraft. . . . all at 20 years of age.

 

 




Crankcase being stripped, 1995.

As can be seen, the entire engine was full of clay which had originally seeped in with water and then dried. It was not difficult to remove, except for the oilways and piston ring grooves, and had protected the engine from corrosion to a certain extent. Everything protruding from the engine, including the propeller reduction gear, was extensively damaged.





 




Crankcase and pistons prior to cleaning

The bearings and crankshaft were found to be in good condition without any measureable wear. There is corrosion on the steel parts including the liners. The crankshaft and connecting rods were all polished to remove pitting.





 




Rebuilt Crankcase Unit

The same components assembled into the new crankcase. I could not salvage the old casing because of the fact that the reduction gearcase was substantially damaged, we can now repair these with new castings which keeps more of the originality of the engine.




 




Supercharger Impeller

The supercharger, or blower provides additional air to the engine to both increase take-off power, and compensate for the reduction in atmospheric pressure as the aircraft climbs in altitude. It is an aluminium alloy forging with separate steel inlet rotating guide vane unit, 10.2" diameter. It has to be very finely balanced as it can run to speeds of 28,500 rpm.




 




Cylinder Block Refitting

Each six-cyliner bank has to be lowered onto the crankcase and pistons, using six piston ring compressors in unison, there is definitely a knack to this operation, especially with the second one, where it is not possible to access the inner side of the block. Quality control inspector Joseph seems happy with the progress!




 




First Run - Spring 2000

After problems with insufficient fuel priming pressure we eventually got the engine to fire up (note the flames from the exhaust) and she ran perfectly. Over a period of time I removed two of the outriggers, and reduced the size of the other two. We now use hydraulic rams positioned inboard of the chassis, but as close as possible to the prop line to prevent the tendency for the trailer to want to tip forwards, just like sitting volunteers on the tail of a Spitfire during high-power runs. This prop was originally a test-club for the R1340 engines of Harvard aeroplanes in test stands, and does not produce much torque. Power at 3000 rpm is no more than 150 BHP, which tends to cause spark plug oiling problems.

The trailer was an ex-Army one ton Sankey for use with Land Rovers.




 




Second Reincarnation

For 2005 I have the engine mounted on a new trailer with both original and replica parts to show how it was originally installed in the Beaufighter. It has now completed 65 hours running.