ive been searching through the forums and i cldnt find anything which tells you how to calculate vertical stabilizer area. can any body help please.
Naji

fnp,

You can use the TLAR (That looks about right) method it works pretty good.

Another method is:

Horizontal Tail:

Pht=Dh/MAC * Sht/Sw >= .55

Pht horizontal tail power, empirical value
Dh distance from the center of gravity to .3 chord horizontal tail, ft
MAC wing mean aerodynamic chord (or average wing chord), ft
Sht total hrizontal tail area, sq ft
Sw total wing area, sq ft

Vertical Tail:

Pvt = Dv/MAC * Svt/Sw >= .3

Pvt vertical tail power, empirical value
Dv distance from center of gravity to .3 chord vertical tail, ft
MAC wing mean aerodynamic chord (or average wing chord), ft
Svt total vertical tail area, sq ft
Sw total wing area, sq ft

Steve

Thanks Steve I was using the TLAR method just wondered if there was any method to verify before i actually built it. Also can you tell me if i use a larger than needed vertical tail or a smaller than needed what should i look out for during test flights to determine my mistake.
Thanks Best regards Naji

fnp,

I'm not sure if I can answer your question....most of the stuff I build has lower Aspect Ratio, short body, and is powered so the size of the tail does not have to be real accurate (at least thats my experence)...another words I have never built a plane that I've really played with the size of the tail to see what effects it might have...nor have I had a plane that I felt had problems because of the tail size... I suspect that as you get in to longer bodies, lower speeds and higher Aspect Ratio a poor tail design is going to be more noticiable.... you might see the following post:

[link]http://www.rcuniverse.com/forum/Erratic_Flight_Behavior/m_1257875/tm.htm[/link]


Steve

What Dipstick said is pretty much how you could do it here with a 99% guarantee of success. The real equations for horizontal and vertical stabs are normally based on amount of drag, moment of inertia and lift. Too complicated for the "fun" part of this hobby. But here is a little bit of info that could help you. For a long tailed model such as gliders, you can get away with a smaller size stab than a short tail model. Its just a matter of balancing the moments.