Ahmad Al-areeqy asked 2 weeks ago
I am trying to conduct an analysis on a biplane airplane on flow5, and I found that the software only count for one wing planform area which results in a doubled tail volume. as shown below, I designed the same model on xflr5 and obtained the correct value for (V_H) the performance results are quite the same when using a same method. however I need to know if this will effect the stability analysis later on before I proceed, or is just a numerical bug which does not effect the calculations.
techwinder Staff answered 2 weeks ago
The reference dimensions are used to evaluate Cl, Cd and other coefficients such as the stability derivatives from the analysis results.
There is an option to include the area of the second wing in the reference dimensions: when defining an analysis, in the “Ref. dimensions” tab, look in the top right corner for the checkbox labeled “Include area of OTHERWINGS”.
The other way to do it is to set the ref. dimensions manually using the “Custom” option.
André
Ahmad Al-areeqy answered 2 weeks ago
thank you for your replying. I have already done this method before ” to include the other wing” in the ref_ dimension tab, however the value still appears the same ” the doubled value of the true value of the tail volume coefficient.” however, I also done the same analysis on Xflr5 with the same parameters and same method, and the results were exactly the same.
hence, I think the bug is in the showed value in the main window in flow5, which is not affecting the calculations. But if this is can be fixed later on it would be great!!
thank you André
Ahmad