V-tail, how to size it?
 

Hello
I am about to start re-design my Riser 100 fuse since the one that comes with the kit it's as fragile as a egg-shell
Since I will renforce it and so forth I want to build it with v-tail just for having something different.
This fuse will be made from scratch.
Does anyone have any information about how to size a v-tail, how much area, what angle, how about the surface controls?, maybe the answer can be in reference with the former fuse, (convenational tail).

Thanks in advance for any help you can provide me with
regards
Omar[:o]

RE: V-tail, how to size it?
 

http://www.charlesriverrc.org/articl...tailsizing.htm

RE: V-tail, how to size it?
 

Omar, Just came across your request for "V" tail information and hope this helps. I've used this several time and it's worked for me...

Good luck..

Regards,
Ron

V-TAIL DESIGN - AREAS & ANGLES

The design of a V-tail equivalent of an orthodox stabilise r and fin.

It is assumed that the vertical (fin) and horizontal (stab.) areas for the conventional empennage are already known, perhaps from previous experience, or from using some design criteria. The requirement is to determine, for the V-tail configur ation:

1.the equivalent V-tail area,
2.the angle between the V-tail and the horizontal.

The diagram represents a view looking along the centre line of the aircraft, the length of each line is proportional to a surface area.


F = the desired fin area,
S = the desired stab. area,
V is the area of each of the V-tails,

x = the angle between the V-tail and the horizontal.

The basic equations for each side are:

1.Vcos^2(x) = S/2
2.Vsin^2(x) = F/2, therefore,
3.(x) = arctan . square root(F/S), for both sides together (from 1 & 2):

i.(F + S) = 2V(cos^2(x) + sin^2(x))
ii.since cos^2(x) + sin^2(x) = 1, then 2V = F + S, ie., the total wetted areas are equal

Example:

Suppose that F = 50 and S = 100 sq. ins.

thus, c alculating the area:

V = 150 / 2 = 75 sq. ins, (ie., the area of each half of the V-tail).

and, calculating the angle:

F/S = 0.5,

tan(x) = square root(0.5), = 0.707,

x = 35.26deg (or, in terms of the included angle of the "V", (180 - 2 x 35.26) = 109.5deg),

RE: V-tail, how to size it?
 

Check out:

http://www.soarcalgary.com/Extras/Ar...%20Spreadsheet

I used Dr Drela's sizing formulas, and at least this way you don't have to do lots of calculations by hand to size things. Call me lazy ;)

RE: V-tail, how to size it?
 

I did a similar conversion of an Airtronics Olympic 650. I was sloping it a lot and wanted more durability. The entire fuselage was glassed with epoxy. [X(] The result was a winged baseball bat!
Calculation showed the stock horizontal tail to be oversize. The horizontal surface was almost all fixed stabilizer and very little elevator. At first I simply removed the vertical fin and rudder, cut the stabilizer and elevator in half, and reattached the stab at an included angle of about 110 degrees. This removed the weight of the vertical surfaces without adding anything, so the nose got quite a bit lighter. The result was a glider that was very stable but not very responsive.
New surfaces were built using the same external shape but with the hinge line moved forward. Now the elevators were more like 35 percent of the total area. This resulted in an easy-to-fly, stable, and responsive glider that would self-thermal with a bit of elevator held. It was a real pleasure to fly and fuselage breakage was impossible! :D

RE: V-tail, how to size it?
 

I have found that most slopers are using 105 degrees to create the V. I just finished a fuse and V tail for a surplus wing. I didn't research the formulas. I just measured the span of the horizontal stab and added 1/4 of that figure to each side of the vee. I kept the cord length the same. I swept the tail back 75 degrees. At the control surfaces, I added 1/4 as well. The plane flys very well and is very responsive.

RE: V-tail, how to size it?
 

Paul,

You might want to check out the July 2002 issue of Quiet Flyer. They have a great article reviewing the "V" tail.

I've used this on both Sail as well as power. My first conversion was a Tower Hobby 40 trainer. I converted it from a tricycle to conventional landing gear and a conventional tail to a "V". I used a mechanical mixer and a low tech 4 channel non mixing, non computer radio... It was my first try and it was terrific. I'm in the process of converting a Genesis Sail from a "T" tail to a "V" . A lot more difficult then the trainer and I'll need a more advanced radio...
Regards,
Rono