RE: Brian Taylor 81
Well, many months after replying to this question I have finally made the maiden flight with my BT Mosquito with 2 x RCV60SP engines.
Details can be found on RCScaleBuilder [link=http://www.rcscalebuilder.com/forum/forum_posts.asp?TID=14905&PN=1&TPN=16]Peterfs 81" Mosquito build log[/link]
In summary, the model weighs 17 lbs 12 oz dry and fueled up 18 lbs 14oz. The engines are RCV60SP and they are from about 2001 - they have been sat around for a long time before being used. They have the Weston UK in cowl silencers. I made the maiden flight with the 16x12 APC 2 blade propellors running up to about 5,300rpm on the ground and there was a lot of thrust, top speed was good but a bit down on expectations. Next flight will be with 15x14 APC 2 blade props to see if I can alter the balance between thrust and speed. The take off run had plenty of acceleration so I have some margin for lower thrust.
I was always a little concerned but people have quoted 9lb planes being flown well on an RCV60SP so I kept these in my model even when I had some doubts and it has paid off, they are completely hidden in the cowls.