The fenestron system is more effective than a 2 or 4 bladed tail rotor, the fenestron system acts as a ducted fan and is extremely effective. The fenestron unit is not just a fan unit in a tube. If you get friendly with one you will see that it actually is shaped accelerate the air flow. The rudder on the model was lower than the proto type and actually pulled the model around when fully deflected. with the proto type we are going from a 7 blade unit to a 13 blade unit. Thanks all challenges makes us double check, answering your questions shows you that we don't use any hocus pocus, no smoke and mirrors. We take all questions to heart none are to silly to address. After all I am only 70 years old and I still can learn...... Al