hinge moment derivatives

[branislav petrovic]

Dear VSP team,

Is there a proper way to calculate hinge moment derivatives Chα​ and Chδ​ in VSPAERO?

Here’s what I tried:

• I created a simple horizontal tail with a full-span elevator and used a symmetric airfoil.

• I placed the CG exactly on the hinge line (rotation axis of the elevator).

• For Chα​: I ran simulations at different angles of attack (with no elevator deflection) and calculated the change in moment divided by the change in α. The result seemed unrealistically large.

• For Chδ​: I applied 15° elevator deflection, compared the moment with and without deflection, and divided the difference by 15° (i.e. Chδ​=Cm​y / deflection

• All runs converged well, and no warnings appeared in the results.

Does this method make sense, or is there a recommended way to isolate and extract hinge moments in VSPAERO?

Thank you in advance!

[branislav petrovic]

is there solution :D :)