Hi RMC, How have you calculated the 20 tonnes at 170 tonnes...?
If they are anything like ailerons, then if an aileron becomes decoupled from its actuation mechanism, it will lift up about a further 3 degrees then obviously would not have any loading either positive or negative.
So again how do you calculate the retracted 20 tonnes...?
It might be possible to guestimate the amount of drag the flaps produce, by seeing how much the glide ratio is increased then using the formula Glide Ratio = L/D, where you know L = 170t so can then find D. (assuming all other controls are not adjusted.)
Putting in some guess figures, If you apply 30 deg flaps and the plane goes from level flight to a downward 10:1 glide slope, then L/D =10 ... L=170 so D=17.. yes...?