LERX on WWII aircraft
 

I always thought the little kink at the leading edge of wing root of P-51D is a high lift device not too dissimilar to LERX on modern jet fighters such as F-18s. However some articles I have read lately said it was none of that. And it was deleted on later H model to save weight. Also, interestingly, almost no US fighters were equipped with leading edge slats as the ones installed on 109s. I know most US fighters emphasized speed, but spring-loaded slats are not really an obstacle to attaining high speed since they are virtually retracted at high speed.

The inner wings on many planes stall before the outer wings where the ailerons are. Having the whole wing stall at the same time is not good design.

Leading edge slats were not held in very high regard among British and American fighter theorists; read any RAE or US evaluation of the Bf 109s they had captured, and there is often (usually) a comment about the slats and an occasional tendency for them to open independently of each other during tight turns, creating an unbalanced lift (this might have been because they didn't get the proper care from Allied groundcrew and techs unfamiliar with them, but I personally doubt this for elite units like the RAE or Pax River test facilities).

Western Allied emphasis was increasingly on speed, range and altitude performance as the war progressed; slats were not considered as great a potential advantage as they were thought of as another thing that could go wrong at the worst possible moment 500 miles away from your home base.

cheers

horseback

I see. But the little kink has no aerodynamic benefit for p51 right? Also, isn't slat gonna help with climbing cuz best climbing speeds are usually pretty low.

The P-51H got smaller main wheels so the inner crank to the wing was not required.