Comments by "David Elliott" (@davidelliott5843) on "Merlin - The Engine that Won the War" video.

  1.  @UncleDon226  Short stroke or long stroke, the Bore/Stoke ratio is irrelevant to compression ratio. Compression ratio is the difference between cylinder head volume at TDC vs cylinder head volume plus swept area of the cylinder.
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  2. The demo engine props are small with fine pitch. The engines will rev, but relatively little power is put out.
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  3. The P51 Mustang was an efficient aircraft needing far less fuel than the P47 Thunderbolt. However even with drop tanks, at full fuel load pilots had to use fuel carefully to avoid upsetting the aircraft CofG. Dropping the tanks too soon could cause serious problems. The P47 had similar range but USAF generals refused to use drop tanks which kept these escort fighters away from Germany. Funnily enough, drop tanks arrived for both types just as the Merlin Mustang came along. The generals used introduction of the Mustang to hide their error in refusing tanks for Thunderbolts.
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  4. Rolls Royce always had an issue with big end failures. Not enough to ruin the engine type but it limited the maximum revs. It was eventually discovered the oil pumps could not keep up with demand. Henry Ricardo ran V Twin test engines (basically 1/6 of the full size engine) which could sustain higher revs without problem. He was using a full size oil pump on a twin cylinder. Upgrading the oil pumps on full size engines significantly improved engine life at high revs.
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