Well,

Now I'm kinda perplexed whether I should use the washer or not. As per Dsegal yeah, my washer came with engine as one engine is Evolution .46 PTS other one I purchased was Magnum .46 XLS. The washer I have, has back side flat and front side is little arched/curved or concaved. Naturally flat side would be touching the prop and lil curved side would be touching the prop nut. I'm also attaching the pictures of My Mustang as well as Escapade. If you may noticed there is a little bit slit between the prop nut and the washer. I have now installed washer on both of my planes. I flew my Mustang without washer did not encounter any problem of spreading the pressure all around prop or confining the pressure at one spot.

Please clarify me, do I need washer or not, or if I may get the thin washer for me Evolution .46 PTS and Magnum XLS .46.

Thank you and pix are being attached for y'all to look closely.

Mody