RE: What Spinner
Hi John,
Unless cost is a factor, Tru-turn makes a 2 1/4 " spinner specifically for APC wide blade props. Tower Hobbies has then for about $28.00 and around $9.00 for the adapter. I have one and it fits a 15x4 easily. Here is a link to the spinner in Tower Hobbies' website.
[link]http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXFBJ8&P=7[/link]
Good Luck,
Ken Pavlou