RE: Flight Trimming Issue:
Ed, i doubt very much that this model design has built in lift for slow flight, just remember when you have a model that has firstly a full type semetrical wing that is set at zero degrees incidence [ 0 ] plus an engine and tail plane that is set to zero [ 0 ] incidence. how would the model get so much lift like trainers do ? what you should be doing with your Viper is to make sure the engine is set to zero incidence, make sure the COG is correct to specs then un glue the tail section and shim the rear by 1/16 th inch. test fly and trim the model for level flight then take note of the elevon positions after the trimming, if there is still up elev trim you need to shim more rear in and vice versa if you have down elev trim. my Viper is new with only 3 flights so far and all is spot on from low to high speeds, my only adjustment was to shim the rear of tail plane by 1/16 inch.