Vertical Tail Size

[Murocflyer]

I am needing the formula for figuring out how big to make my vertical tail on my homebuillt plane. I have posted build photos here (http://www.rcgroups.com/forums/attachment.php?attachmentid=795563).

Modeling Science seems to be viewed more so I am asking the question here.

What are the requirements to determine vertical tail size? I have Andy Lennon's book, but to me it doesn't spell out measure here and here, then divide this by this, then square for the ARv. I need something I can understand.

Any tips/advice/links would be greatly appreciated.

Frank

[CloudyIFR]

Download Sailplane Calc and it'll tell you.

Curtis
http://h1.ripway.com/cloudyifr/files.htm

[HELModels]

Dont be afraid to use TLAR on that vertical. Look at the squirt as a reference. It seems to have very similar proportions to your scratch build in every respect except the vertical. Calculators are a great tool, but eyeballing it can work too.

[BMatthews]

Go a Google on "vertical tail volume coefficient". The actual size is not critical to the exact %. Instead it's more about an acceptable range of size. For a polyhedral wing the center of the range is a bit higher than the center of the range for a flat wing. And similarly high wing cabin designs need to be slightly bigger than low wing designs.

[Murocflyer]

OK, still trying to figure this out.

I found this site:

http://www.djaerotech.com/dj_askjd/dj_questions/tail_coef.html

Thanks again for the help.

Frank

[Murocflyer]

Dont be afraid to use TLAR on that vertical. Look at the squirt as a reference. It seems to have very similar proportions to your scratch build in every respect except the vertical. Calculators are a great tool, but eyeballing it can work too.


I tried the TLAR in comparison to the SQuiRT. I came up with a vert area of 45 sq inches. Doesn't seem possible. This is almost as hard as the landing gear dilemma

[Murocflyer]

I couldn't find a reference for a formula on how to size the vertical fin so I did the TLAR method. One day when I do find it, I'll verify. I'll have to find it eventually since I have another build planned. This one not so big. My goal for that one is light although I would like it to be about 24" in length. I'd like to try out the IPS power system in that one.

Thanks again for the replies.

Frank

[CloudyIFR]

OK, still trying to figure this out.

I found this site:

http://www.djaerotech.com/dj_askjd/dj_questions/tail_coef.html

Thanks again for the help.

Frank


This is where I got the formulas for the spreadsheet on my website.

Curtis Suter
Edwards AFB 1992-1996 and 1999-2001

[jfv]

For a sport model, rule of thumb is to make the vertical tail 8.5 - 9% of wing area. The rudder should be about 35% of the total vertical tail.

[Murocflyer]

This is where I got the formulas for the spreadsheet on my website.

Curtis Suter
Edwards AFB 1992-1996 and 1999-2001


Curtis,

Great job on your spreadsheet, it will come in very handy!

Frank

Edwards AFB '98 - '01 (3 was enough :) )

[CloudyIFR]

Edwards AFB '98 - '01 (3 was enough :) )


Thanks for the kudos on the spreadsheet.

Anytime there was more than enough, no offense! Best was the 6 years in Germany.

Curtis
Born and raised in Harrisonburg, VA
Now living the dream in Montana

[Murocflyer]

For a sport model, rule of thumb is to make the vertical tail 8.5 - 9% of wing area. The rudder should be about 35% of the total vertical tail.

Thanks jfv, but I wouldn't consider this a "sport" model. Would 10 -12 % be a better number in this application and 50% for the rudder?

Thanks.

[Murocflyer]

Thanks for the kudos on the spreadsheet.

Anytime there was more than enough, no offense! Best was the 6 years in Germany.

Curtis
Born and raised in Harrisonburg, VA
Now living the dream in Montana

Curtis,

None taken.

Living the dream in Montana...you gotta love that!! Good for you.

Frank