"Maximum weak mixture"

[Mifletz]

Gunston in "Nightfighters" states that if the RAF had run their Lancasters at "maximum weak mixture" power, their speed would have risen from 200 to 270 mph, with a penalty in engine overhaul life and fuel consumption, but with many less interceptions taking place.

Is this correct?

[Graham Boak]

To gain maximum range with piston engines, it is advisable to run them at lean mixture and high boost pressure. Apparently this fairly basic knowledge was not imparted well in WW2 training given to pilots - this is the technique Charles Lindberg imparted to the P-38 pilots in the Pacific, reportedly giving them a considerable range increase.

It seems as though this technique, but running at the maximum rpm available in lean mixture, is what Gunston is suggesting. Without knowing how Bomber Command pilots did handle their aircraft, and detailed aircraft/engine cruise information, it is impossible to say how accurate he is, though 270 knots seems rather high. Given that Bomber Command did include a flight engineer in the crew, with rather fuller education on engine handling, I suspect these supposed benefits may not have existed.

It is probably true that the higher the speed, the fewer the interceptions, though this may not be sensitive until higher speeds are reached. Most German nightfighters would still have had an advantage over the Lancaster.

What is also true is that the admitted increased fuel consumption would have significantly reduced the Lancaster's range, thus preventing it from reaching deeper targets. Reduced penetration ranges would again reduce losses, of course, though the German defences would be able to react differently, and reduce this effect.

I think that, without fuller information, we should assume that Bomber Command's planners were well aware of the performance capabilities and options of their aircraft, and that the tactics were adjusted to gain maximum benefit.

The same comments apply to the other types, not just the Lancaster.