Mr. 'Scientist' needs to talk to some radio-controlled modelers.

A number of them have built R/C Pterosaurs and thermalled them just fine after they worked out how to use the head as a rudder.

http://www.youtube.com/watch?v=ucE-xUIQ_rI

Not that they would have had to thermal much if they stayed at the coastlines or mountain ranges where they could take advantage of ridge lift (or slope soaring as we call it...)