Also wenn hier keiner was zur EWD sagen kann dann befrage ich jetzt mal die künstliche Intelligenz:
@ChatGPT:
God evening, I am building an RC1 modell aircraft with a wing load of 80g/dm^2 and a Design speed of 150 km/h. Wing profil is 18% Thickness , fully symmetric. Which inclination between wing and elevator wing would you recommend, if I like to fly with a very backward orientated center of gravity and very limited aerodynamic stability
answer:
Good evening! For your RC1 model aircraft with the given specifications, setting the correct incidence angles between the wing and the elevator is crucial, especially considering your preference for a very backward center of gravity (CG) and limited aerodynamic stability.
Here are the key points to consider:
- Wing and Elevator Incidence:
- Main Wing Incidence: Typically, the main wing incidence is set between 0° and 2° relative to the fuselage datum line.
- Elevator (Horizontal Stabilizer) Incidence: For a symmetric airfoil and the goal of limited stability, the elevator incidence should generally be set at a slightly negative angle relative to the main wing to provide the required balancing moment.
- Rearward CG Considerations:
- A rearward CG reduces the aircraft's natural stability. To compensate, you need to set the elevator incidence such that the aircraft maintains a stable pitch attitude at your desired flight speed.
- Balancing Pitch Stability:
- For an aircraft with limited stability, a small negative incidence for the elevator relative to the wing (also called a decalage angle) is usually sufficient. This typically ranges from -1° to -2°. This helps ensure the elevator provides a slight nose-down force to counteract the nose-up tendency from the rearward CG.
Recommended Incidence Angle
Given the symmetric airfoil and your design preferences:
- Wing Incidence Angle: 0° to 1° (relative to the fuselage datum line)
- Elevator Incidence Angle: -1° to -2° (relative to the wing incidence angle)
This setup should help achieve the desired flight characteristics. However, keep in mind that adjustments may be necessary based on actual flight tests. You may need to fine-tune the incidence angles to achieve optimal performance and stability for your specific model.
Practical Tips:
- Initial Test Flights: Conduct initial test flights in calm conditions and be prepared to make small adjustments.
- CG Position: Carefully measure and adjust the CG to ensure it is as desired. Moving the CG even slightly can have a significant impact on stability and control.
- Trim Adjustments: Use trim adjustments during flight tests to fine-tune the balance between wing and elevator incidence angles.
Safety Note:
Flying with a rearward CG and limited stability can lead to challenging flight characteristics. Ensure you have the necessary experience and be prepared for potentially rapid and unpredictable responses from the aircraft.
By starting with these recommended angles and adjusting based on actual flight performance, you should be able to achieve the desired handling characteristics for your RC model aircraft.
ChatGPT
Na das ist doch mal eine Ansage!!
Negative EWD im Fall von starker Schwerpunktrücklage!
Also könnten die Null aus dem Kato Plan gar nicht verkehrt sein…
Vom Gefühl her würd ich trotzdem lieber eine positive EWD wie normal üblich verbauen…
Wieder sind gerne die Meinungen der Experten gefragt…
JB