According to the characteristics of the compound coaxial helicopter

the general aerodynamic forces and moments of rotors

wing

fuselage

stabilator

vertical stabilizers (containing the rudder) and propeller were modeled and a trimming equation set was established accordingly.In view of the controlling redundancy problem

a control strategy was studied for the compound coaxial helicopter under conversion mode

using the linear transition method and minimal power optimization transition method.A sample compound coaxial helicopter was taken as an example to demonstrate the effectiveness of the method.Then the trimming values

the attitude angles and the power of these two methods were compared.The result shows that both the two methods can solve the controlling redundancy problem

while the trimming values and the attitude angles are reasonable and the linear transition method is better in the smooth change of the control values

the difficulty level of the controlling system and the flight quality.