From Brian Thorby who has restored one which was also once
destined for a UK 500cc car but never quite made it.

1943 Lawrance Series 30 Auxiliary Power Unit (APU) Air-Cooled Engine and DC Electrical Generator

This 500cc (30 cu in) twin-cylinder air-cooled ohv engine was close-coupled to a 5Kw 28 volt DC electrical generator in line with the crankshaft. The complete installation was mounted within a sound-insulated casing aboard several types of WWII allied aircraft to provide on-board electrical power independent of the main engines. This unit would have been installed in Consolidated Catalina  Mk I & Mk IVb Flying Boats, operating from Woodhaven by Wormit on the Tay Estuary.

On 10 May 1943 1477 (Norwegian) Flight RAF, manned by Norwegian aircrews who had escaped the occupation of Norway in 1940, arrived in Fife to fly D.H. Mosquito fighter-bombers at Leuchars, and Catalina Flying Boats based on the Tay at Woodhaven. The Mosquito crews were  moved to join the Banff Strike Wing in Morayshire in September 1944, leaving the Catalinas as a detachment of 210 Squadron Coastal Command RAF. The first Flying Boat, Serial W8424, alighted on the Tay on 18^th May 1943, and was named Vingtor. Until 1945, these long range anti-submarine and reconnaissance machines performed valuable anti-U-Boat escort for convoys, and also ferried personnel in and out of occupied Norway, where the crews’ intimate knowledge of their homeland came into play.

On these long flights of up to eight hours duration the Lawrance APUs droned away at an amazingly fast speed of 4,000 rpm. When peace came in 1945, the Catalinas were flown to Oslo as 333 Squadron, passing to the control of the Royal Norwegian Air Force. The PBY Catalina remained in Norwegian service though various marks until 1961, until a suitable replacement long range coastal patrol aircraft was available. These aircraft would have flown overhead Montrose on virtually every flight from Woodhaven during the war. The people of Wormit, close by to Woodhaven Pier, have maintained contacts with Norway in memory of their wartime visitors who fought bravely in exile until their homeland  was liberated.

In emergency, besides charging batteries and powering communications equipment, the APU could also power bilge pumps, in the event of the PBY’s hull being holed by enemy action or striking submerged objects. The engine is designed and constructed on typical aviation principles with twin magneto ignition systems; high-specification materials and finish. The compression ratio of 9: 1 is very high for a stationary engine, but was specified to suit high octane aviation fuel. A five cylinder radial-layout version was supplied for use on American B-24 Liberator Bombers, used by RAF Coastal Command as well as by their own USAAF Squadrons.

This Type 30D Lawrance APU engine was restored by Brian Thorby of Brechin during 2009, as a loaned exhibit for Montrose  Air Station.

From MASHC TECHNOTE No. 007