The first increase in pitch away from the 11x7 Rev-up type props was to reduce noise. At the same time soft mounting started to come into play. My first soft mounts were on an Atlanta, home made from a design stolen from Dean Pappas. That with D&W 11x9 wides on a YS short stroke gave the same performance as the 14K+ Rev-ups with much less noise. Later higher pitched props were used on long strokes for both noise and speed reduction as turn-around came into place.

Stuart C.