I use the 16x4W on my YS91 in a U Can Do. At sea level, it turns 9100 static and hovers the 7lb 9oz. plane easily. I can't say how it would be at your altitude especially with a heavier plane. If I had to guess I'd say you want more diameter. If you could find a 17 or 18x4 that would probably be the ticket.

David