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# Aerodynamic Trim Conditions

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## Aerodynamic Trim Conditions

(OP)
Hello all,I have a program which requires input such as Velocity, Angle of attack, and Fin deflection.

The program goes through and calculates the aerodynamic coefficients for my vehicle, then outputs my Forces and Moments on the body (Fx, Fy, Fz, Mx, My, Mz).

I need to make a "wrapper" of sorts that can find the trim conditions of my Vehicle.  In other words, I would like to set my Moments all equal to zero, and have the trim wrapper iterate until it finds what fin deflection will give M = 0.

Is it possible to do some sort of numerical analysis in Matlab to do this?  I am not sure where to start, is there a paticular method I should be looking at to do this?

Thanks in advance for your thoughts.

### RE: Aerodynamic Trim Conditions

i think you may be confusing "trimmed" with "balanced".  to analyze a plane we use balanced load cases; usually statically balanced thought we can balance with inertial forces.  the loadcase starts with the "point in the sky" ... eg straight level flight, for a particular payload configuration.  we need to determine the horizontal tail load which is added to the airplane weight to define the required wing lift (for a conventional airplane layout).  the (pitch) attitude of the airplane is the variable which affects wing lift, tail lift, and wing moment.  i'm sure you could set up an iteration analysis in matlab or excel to solve this.

trimmed flight, IMHO, refers to the pilot adjusting the trim controls to save having to keep a constant load on the sitck to maintain the flight attitude he wants.  also i think trim tabs create the required lift with less drag.

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