Aileron Plans
- simon.gorbet
Hinge Method
Custom 3d printed hinges using Foam Tac, epoxy or other types of adhesives to keep the hinge in the wing. Make sure the adhesive used will not damage the wing/aileron material.
As for the pin of the hinge we were initially thinking of using Chicago screws but I couldn’t find any with a dimeter smaller than 5 mm which means the hinges need to be relatively thick. The thicker the hinges the more difficult they become to install. As a smaller alternative we could try a straight cotter pin.
Something I forgot to add to the hinge page last time was hinge moment positions. Other than forum writer opinions it doesn’t seem like one is better than the other. One point that did stand out to me though was that center hinge moments have the most material above and below them creating a stronger mounting area. Frise hinges help counter adverse yaw but can complicate geometry (later in the page I talk about a simpler solution).
Sealing The Hinge Gap
When making the plane it is something we should look into. It doesn’t require much planning ahead but it can make a slight difference. Sealing the aileron hinge gap can help create more lift at lower speeds, especially when the ailerons are out of position.
Sealing the Aileron Hinge Line | AMA Flight School
Countering Adverse Yaw
Adverse yaw is the tendency of an airplane to yaw in the opposite direction of the turn. For example, as you roll to the right, your airplane may initially yaw to the left. The aileron angled downward (the left aileron in this example) produces more drag and more lift, initially yawing the airplane in the opposite direction of your roll.
Adverse Yaw: How It Affects Your Plane
Frise Ailerons
As previously mentioned Frise ailerons can help reduce adverse yaw by making form drag to counter induced drag.
Differential Ailerons
One aileron is raised a greater distance than the other aileron is lowered. The extra upward aileron movement produces more drag change than an increase in AOA on the downward aileron. This produces an increase in drag on the descending wing, which reduces adverse yaw.
Personally, I think differential ailerons are the way to go because they can be easily implemented through the radio/code or mechanically and are more adjustable in the future than Frise ailerons.
Aileron Location and Sizing
Thoughts? I couldn’t find any info on the difference they make during flight.
Determining Aileron size
The size of the aileron will influence our roll speed. Once we decide on a desired roll speed and have more detailed wing dimensions (max cord length and max individual span of a wing) I can start calculating specific dimensions for the aileron.
http://www.flightlevelengineering.com/downloads/ProAdvice 3 - AILERON SIZING.pdf
The standard for RC planes are shown in the diagram above.
Cord length of aileron = 1/4 of cord length of wing
Aileron length = 1/4 of wing span
As more percentage of wing becomes aileron the roll speed increases. If we are interested in deviating from the standard, there are formulas for determining aileron dimensions based on desired roll speed for “Hershey Bar Wings”. Hershey Bar Wings are rectangular wings with a constant chord length.
http://www.flightlevelengineering.com/downloads/ProAdvice 3 - AILERON SIZING.pdf
For reference the expression pb/2V can be used to compare our roll authority to other planes where p is the roll rate in radians per second for full aileron deflection, b is the wing span (in m), and V is the airspeed (in m/s). For example a cargo or heavy-lift plane has a ratio greater than 0.07, a fighter jet has a ratio greater than 0.09.
Selecting Servos
To properly select the servos we need to know a few things:
The max span of the wing (used to calculate aileron details)
The max chord of the wing (used to calculate aileron details)
Desired roll speed (used to calculate aileron details)
Desired max air speed
These features and the dimensions of ailerons formulated from them will allow us to use the formula below
Calculator: RC Airplane Calculator
A good starting point for selecting servos is their classes. Servos can be classified into different sizes as shown below:
Based on the table our plane would use Standard size servos but we should still verify with calculations.