[Graham Boak]

The stall strip is not a straightforward alternative to washout, but usually used (as on the Corsair) on one wing to make the stall completely predictable on aircraft where the stall can mean unpredictable wingdrop to either side. It was also used on the Grumman Tiger light plane, presumably for similar reason. It is a cure for low speed bad behaviour, and tells us that this was present on the Dornier.

Washout is to allow for the wing twisting with load, as incidence increases. This because this twist increases the incidence of the tip above that of the inner wing, so that the wing stalls at the tip first giving wingdrop. In combat turns, it may be unpredictable which wing drops first. A few degrees of washout gives the aircraft extra lift at the tip, and hence can go to higher incidences giving better turning performance.

I don't know which was the first type to introduce washout, but the Spitfire had 2 degrees, and I suspect that the Fw.190 had similar. Other types of this period (eg Bf.109) used outboard slats but this had other drawbacks such as increased drag.

The same principle was behind the poor stall behaviour of the Dragon Rapide, with its narrow pointed wingtips, but in this case the effects showed at low speed rather than in combat turn.