I whack out various shapes of flat foamies - then go fly -all in a short space of time -
One interesting point -is in boldly increasing area of the fuselage - above or below the thrust line - with the thrust line remaining on the centerline of wing and stab. The models change how they respond in yawing - such as flat turns .
Also if you place the battery pack above or below - the yaw is again affected -
These small models really are a boon to those who want to see what is going on --first hand -rather than trying to apply info developed in wind tunnels etc., which may or may not be very relevant to a hobby aircraft.