Well, as I am a guy who believes in what can be seen and felt. I have to honestly say that in 36 years of flying R/C I have never seen nor felt anything I could contribute to spiral slip stream. I will agree that it plays a part in full scale flying however I have always believed that because our models are smaller, lighter loaded and have much more power to weight that some things just don't affect the models as much. IMO if spiral slip stream does play a part on our models, is such a small affect as to not warrant any real consideration. I think that most guys don't ever fully trim their airplanes which would have a much larger adverse effect then what we are discussing here.