Hot Spot Drivers,
I have the Graupner Hot Spot and it calls for 8-10 mm of uptrim on the elevons. This is due to the non-reflex airfoil on this version. I understand that later versions utilized a true reflex airfoil which is required on tailess delta planform aircraft. A forward canard may eliminate the need for this uptrim.
Using engine thrustline changes to compensate may only work at certain airspeeds, typically low speed where the aerodynamic forces are miminal. As the airspeed increases these forces dominate which may help in the overall flying characteristics of the Hot Spot. I don't like the use of elevon uptrim but will live with it on my model. Further discussion on this would be appreciated.

Art ARRO