I had never heard of planesail before, it is interesting. Kind of like a sailing Fokker ( I just had to say it).

The problem with all of these wing designs except for Greenbird is that they don't incorporate a horizontal stabilizer, they turn the whole tail which isn't 'stable' hence the need for a stabilizer. A tail feather alone will simply increase the angle of attack until it stalls, it is very, very hard to control properly.

I agree with you on the importance of the bearings.  The stabilizer needs to be sized to overcome sticky bearings and the mast and stub need to be strong enough to handle a fully stalled wing.  The question becomes what wind velocity should the system be able to handle before collapsing.  Right now the worst case Cd seems to be 2.1, about double the expected Cl and below the standard safety factor. . .

Talador

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