Modelling wings with flap and aileron

[Rahmathulla P]

Hi Cory,

I’m making progress with aircraft design using MachUpX programmatically. However, I have some questions regarding the modelling of the main wing and your help will be greatly appreciated. I’m trying to make a model of the following.

When I modelled the main wings, I excluded central portion of the wing for the fuselage with “y-offset”. Is it necessary? If so, would it create root vortex similar to tip vortex? Without “y-offset”, would it overpredicts the lift?

I have some questions around modelling flap and aileron within the main wing.
Using AirfoilDatabase, I have created a database with dof’s including “trailing_flap_deflection” and “trailing_flap_fraction”.
For the main wing, as you see in the above figure, there is flap and aileron surfaces. In the “Aircraft Object” -> “wings” -> “<WING_SEGMENT_NAME>” (in this case main wing), there is only one “control_surface” to define “root_span”, “tip_span” and “chord_fraction”. I used this to define the aileron with root span of 0.55 and tip span of 0.95. I understand the “chord_fraction” definition is same as “trailing_flap_fraction” of AirfoilDatabase. I don’t know how to define the flap parameters as there is only one “control_surface”. Could you please clarify this?

Next question is how I can set the flap deflection. In the “Scene Object” -> “aircraft” -> “<AIRPLANE_NAME>” -> “control_state”, I can provide the aileron setting. I understand that this aileron setting is same as the “trailing_flap_deflection” of AirfoilDatabase. I don’t know how to set the flap angle, as I have not defined the flap. Could you please clarify this?

Regards,

Rahmathulla

[Cory Goates]

Hi Rahmathulla

Typically, you do not separate the wings to account for the fuselage in between them. Rather, just extend the wings through where the fuselage would be. This is one of the limitations of lifting-line theory. It's generally considered that this does an okay job of predicting lift, while underpredicting other fuselage contributions to drag, stability, etc. So keep that in mind with your results.

To have both ailerons and flaps, you'll need to model the main wing using two separate wing segments. The control surface on one segment will be the flaps and the control surface on the other will be the ailerons. You are correct about "chord_fraction". Just make sure to set "main_wing" : True for both. Once you do that, you can set the deflections using Scene.set_aircraft_control_state().

Hope that helps! Let me know if you have more questions!

Cory