V-Tail control surface proportioning
 

Hi everyone,

I came into possesion of a Robie Disco HLG. I am intrested in converting it into a V-Tail instead of the conventional as per plans. I'm using a ligher radio than the plans show, and I figure I should lighten the tail to keep the balance in check. Besides, I think V-Tails look way cooler.

I found some refrences as far as sizing the new Tail surfaces and determining the angle. However I am unsure if the ele-rudders(What are they called anyways?) count twards the tail area or not. (I presume they do) and I am unsure how to proportion the control surface to the stabilizer. Any suggestions of a ball-park figure. Im not really interested in competition, just a nice flying HLG to mess around with.

Thanks in advance.
Rico

RE: V-Tail control surface proportioning
 

I'm not sure of the exact formula - if there is one - but they are usually called "ruddervators".

I would guess that the "V" surfaces would need to be slightly larger than the conventional elevator/stab; at least so that the same area is "projected" by the new surfaces.

RE: V-Tail control surface proportioning
 

I generally use the elevator size in terms of chord from the normal setup for the surface size on a v-tail. Span to suit.

RE: V-Tail control surface proportioning
 

Hey guys, thanks for the feedback.

I think I'll make them just a little bigger than the elevators on the plan... I was wondering about something. How can a V-Tail be lighter if the surface area remains the same? Just a thought. I'd probably still make the mod just because I like to mess around with stuff like that. ;)

Thanks for the help.
Rico

RE: V-Tail control surface proportioning
 

Don't think surface area - think frontal area. You're still reducing the number of things in the slipstream from 3 to 2. And cutting down the intersection drag where they attach to the fuselage. Plus the weight of associated hinges, pushrods, and other hardware...

It's a good theory, but I guess there must be some reason that just about every plane flying still has a conventional tail. There's still plenty of old Bonanzas around!

RE: V-Tail control surface proportioning
 

I like v-tails because the tips are way above the ground when I land. Usually the landing areas I fly at are inimical to things sticking out... and the tips don't get scuffed when I land on a runway with my gliders.

RE: V-Tail control surface proportioning
 

I can see how the frontal area would be less than a conventional tail, but I can't see how they would be lighter... still the same pushrods and control horns, and I would imagine that equal surface area means equal mass in materials and they would weigh the same. I guess the diffrences are exagerated with a built-up stab vs. a solid piece with holes. I should just stop contemplating this. It's trivial.

Does a properly designed V-tail give the same control authority as the conventional counterpart? Also, do v-tails exibit a sort of adverse roll with yaw inputs? (It kind of seems like they would work as ailerons in a way)

Rico

RE: V-Tail control surface proportioning
 

Here's a good treatise on v-tails.. and the charlesriverrc site should be on everyone's bookmark list..
http://www.charlesriverrc.org/articl...adverseyaw.htm

RE: V-Tail control surface proportioning
 

That addresses the roll question quite well. Thank you.

Good stuff, these v-tails.[8D]