his bird will have retracts, brakes, fowler flaps, functioning ramp/door, cargo rails,
+ 4 x 35s
I don't see this coming in at 15 lbs.
20+ lbs more likely.
I know of a 1/12th scale Avro Lancaster [ 102 in span ] that came in around 15 lbs or more. It was built light mostly of blue foam covered in Brown paper and used 4 x 15s It did have retracts and flew in a very scale like manner. I mean the real one was rolled and did fly inverted!
http://youtu.be/1IsRp_QLwd8