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That is the background info on what empennage is and how it works.
Author: Thushanth Parameswaran updating Date: 2024/07/21
Source: https://www.fzt.haw-hamburg.de/pers/Scholz/HOOU/AircraftDesign_9_EmpennageGeneralDesign.pdf
General Design Rules
The lever arm of the empennage should be as large as possible. (Lever arm is the distance between the aerodynamic center of the wing and the horizontal stabilizer). This will reduce the size of the empennage, saving weight.
The aspect ratio of the horizontal stabilizer should be about half the aspect ratio of the
wing.Horizontal Stabilizer is fixed, an incidence angle of around 2° to 3° downwards
should be chosen to create a negative lift. (assuming we are using asymmetrical airfoil)Symmetrical airfoils are exclusively selected for vertical Stabilizer. (NACA 0009 might be a good start)
Horizontal stabilizers can be either symmetrical or slightly cambered to produce negative lift.
Design by Calculation
https://www.fzt.haw-hamburg.de/pers/Scholz/Aero/AERO_PUB_INCAS_TailVolume_Vol13No3_2021.pdf
Using the tail volume coefficient, we can estimate the horizontal and vertical stabilizer sizes.
https://www.reddit.com/r/RCPlanes/comments/1az1gjn/tail_volume_coefficient/#lightbox
A Reddit gave what tail coefficient to use. It said .672 for CH and 0.0657 for CH. Based on this value
Airfoil is NACA 0009 for both Horizontal and Vertical.