Propping the YS91AC/FZ
Rob,
I have had a few, and still have 3 YS91ACs. The YS91AC will pull anything from an apc14x10 for fast planes to some modified Zinger16x6 for fun fly planes. For aerobatic planes I like the apc15x7, it's a light load, so the engine is responsive. If you want a fast but responsive plane, you could start out with the apc 14x8, maybe apc15x8. This is all on YS20/20 fuel.
DKjens