I don't know who said 4" was scale, but it's not even close.
Even 3 1/2 is too big.
3 1/4 would be the way to go as scale would be 3 19/64"
You did earlier on this thread, later you restated 3 and 1/4 would be more scale
[quote]The SkyShark kit is just a wee bit smaller than 1/7th scale (59 or so inch wingspan, I forget exactly what), the KMP has a 70", which is 1/5.85 scale, the spinner from SkyShark is going to look silly.
You are going to need a 4" diameter spinner for the KMP bird.[quote]