# What is the maximum roll rate for an RC aircraft of low maneuverability?

I'm a student of mechanical engineering and my graduation project is basically an RC aircraft powered by a propulsion system and It is used for general transportation. The aircraft doesn't require much maneuverability. The problem is that when I was designing the ailerons using the design equations included in the reference 'Aircraft Design A Systems Engineering Approach by Sedraey', the roll rate calculated was roughly 12 rad/sec, which is probably a large number for an aircraft that doesn't require much maneuvering.

My question is of course a sanity check; is this roll rate reasonable ? because I used MATLAB for optimization of the geometric parameters of the aileron and the output geometry seemed logical when I visualized on SOLIDWORKS.

Update : I looked up other reference which are specialized in aircraft stability and control and I have finally managed to get reasonable results. From my experience I would never recommend using 'Sedraey' as a reference for learning about aircraft design. Thank you all for helping me.

• I’m voting to close this question because it belongs on Drones.SE.
– Ralph J
Nov 9, 2021 at 19:40
• Something is wrong in these formulae. How do they willy-nilly assign [m/s] to $y_D$, while it is clearly just [m]? If $L_A$ is the roll moment from ailerons ([N m]), then (12.37) will indeed be [1/s], but 1) randomly picking "drag moment arm" at 40% while the main resisting force, roll damping, is proportional to the square of wingspan, seems wrong. And 2) this $L_A$ will decrease with the roll rate (simply because the local angle of attack will partially negate aileron deflection). Very suspicious source.
– Zeus
Nov 10, 2021 at 8:58
• Roll rate will be dependent on the airspeed. A model airplane will generally be flying at around 20 knots. The V$^2$ is used to calculate the roll torque based on the lift difference of aileron up and down. Roll rate stabilizes when drag torque equals roll torque. Weight placement in wings is also critical. 1 radian per second is more like it. Comparison with existing R/C models may be helpful, as would speaking with their pilots. Nov 10, 2021 at 11:34
• I agree with you that these equations are quite suspicious. It would be helpful if you referred me to a better resource, especially if it is related to RC airplanes. @Zeus Nov 10, 2021 at 17:53
• I think talking to RC experts and pilots would give me a better insight and intuition. @Robert DiGiovanni Nov 10, 2021 at 17:58