Looks L-4 to me. A lot of the props were painted with yellow tips in the field. (not by Sensenich or Fahlin). Looks appropriate to me if your grandfather flew L-4s... Wonder what the backstory is on just how it came to be seperated from the rest of the prop... These aircraft were nothing more than jeeps to beat up for the common GI and airmen, so they went through a lot of props...