I've been thinking about variable geometry ("swing wing") designs lately and I think it'd be interesting to see a scratch built variable geometry wing challenge between Josh and David to see who comes out on top.
http://www.youtube.com/watch?v=geFHBUom2SA
http://www.youtube.com/watch?v=wmeYQmCs4vY&list=WL9438059E64023985
http://www.youtube.com/watch?v=geFHBUom2SA
http://www.youtube.com/watch?v=wmeYQmCs4vY&list=WL9438059E64023985