Tail volume coeffiecient software?

[Yochim]

The Multiplex website used to have a TVC calculator that was witten by Mark Lavoe and now it has disapeared.

Does anyone have it on their PC and if so would you be so kind as to e-mail it to me at yochim_d@hotmail.com ?


Thanks in advance.



Y.

[Ollie]

IMO a program to calculate a number only requiring two division operations and one multiplication operation is overkill. A simple pocket calculator is more than enough. Pencil, paper and a knowledge of multiplication and division are quite adequare.

[SoarNeck]

This will do it...

http://www.soarcalgary.com/Extras/Articles/Sailplane%20Design%20Spreadsheet

[Yochim]

Wow, thanks a lot for that link!

I do have a question, in the "Stability Parameters" section should "B" = "5" or ".5"?

If I make B = 5 the tail has to be enormous so am I doing something wrong?

And is V(v) the vertical TVC and V(h) the horizontal TVC?

Also I can not find a ReadME document with the software, is there one available?

Thanks again.



Y.

[Yochim]

And one more question if I may, is the dihedral input in degrees or inches?


Thanks.



Y.

[SoarNeck]

Hi Yochim,

Glad you found the sheet useful. It's a bit utilitarian, but I didn't really build it with the intention of other people using it...I just got my arm twisted to release it! :)

The dihedral input is in degrees, relative to a horizontal datum (ie flat wing).

B = 5 only for a balanced RES model. I've flown RES airplanes with B as low as 2.69 (my Paragon), but they always feel sluggish (large yaw -> roll delay). I ALWAYS design for B=5 for RES models nowadays. If memory serves, Mark Drela uses this number for his Bubble Dancer and Allegro RES versions as well.

Aileron models (sailplanes) can use B=0.5-2, depending on personal feel. Pylon racers usually use B=0 (no inherent stability).

There's no read-me file beyond what's on the webpage, but I can answer any questions that you might have here.

Cheers,
Adam

[SoarNeck]

B is more dependant on dihedral angles, BTW...tail size (I assume you mean length) isn't as big a factor. Other inputs that are relavent include span and airfoil CL.

Here's a tip: design for stability using CL=0.7 instead of the max cl of 1.0 or 1.1 (for most airfoils). That's more of a realistic interpretation of average-speed thermalling conditions.