V-tail vs. Conventional rudder/elevator.

[Sheriff]

What is the difference in flying characteristics and performance between a V-tail configuration like what is found on the new parkzone Slo-V and a conventional ruder/elevator configuration like what is found in a slow stick.

I'm not interested in the planes themselves, they are just examples that I am familiar with. I'm just interested in the difference between the two tail types for a plane that I am scratch building. Not sure what type of tail to go with.

Thanks for any information.
Harv.......

[Sparky Paul]

For the planes noted, I don't think anyone could say one is better than the other.
For larger planes, there's real reasons for and against..
http://www.charlesriverrc.org/articles_modeldesign.htm
I like them because they're different, easy to set up, and for a lot of the areas I fly out of, practical as the tips are kept off the ground/rocks/sand when landing.

[Andy W]

What he said, plus a T-tail tends to require more structure at the root of the vertical, as a lot of stress is placed here during abrupt stops (spot landing, say). Without extra structure, the tail can break off or split.
..a

[robert harik]

You can build a v tail lighter than you can a conventional design. Thats important where weight is critical , like on small hand launch gliders. Depening on the moments, 1 extra gram in the tail can mean 3 in the nose.

[GaryMC1]

Mr. Harik,
I would disagree with you for the very reasons that Andy specified for the "T-Tail!". V-Tail, often referred to as 'ruddervators', can cause a high torque, or torsional twisting effect along the rear fuselage, and can cause significant damage, or has happened in real life many times, seperation of the tail of the aircraft from the fuselage. Therefore, stiffening of the tail area and tail connections to the fuselage must be stronger and stiffer, therefore adding weight to the rear of the aircraft. Of course, in the real Beechcraft Bonanzas, which utilize the V-Tail, there have been numerous 'tail flutter' accidents, leading to fatal crashes.

While the V-Tail is an elegant design, as far as forces acting on the tail of an aircraft, either R/C or real, I would rather have the standard stabilizer/vertical fin-rudder design over the V-Tail.

Gary

[robert harik]

Garry ,I guess it depends on the application.
I use them on small hand launch gliders. I can build a v tail for about a third of the weight and they are strong enough for what I need them to do ( never had a failure).

Would I use them for any other reason, no. Other than looking good, I cant think of any other reason than weight.

As for the Bonanza, you cant design any structure to withstand flutter.
Flutter is an aerodynamic problem, then comes the structural problems.

I have worked on more than few full sized Bonanzas and the tail mods I have been told dont add that much weight. Thats really not the point though, dont blame the v tail for design flaws made by Beechcraft.

[ChrisP]

As my electric powered sailplanes have got old and needed replacement I have phased over entirely to V-Tail without ailerons.

I now have 4 : FVK Prima, Conrad Swing, FVK Silent Dream, Kyosho Tic Tac II. The nice thing about FVK is that they will happily build you a V-Tail version of a model if it doesn't have it as standard. They did this for me with my Prima for no extra cost.

I find that the models turn very crisply. I'm tempted to say 'even better than with ailerons'. The wing is certainly aerodynamically more efficient and easier to build.

I was never a fan of crow ailerons, so I don't miss that feature. Two of the models have a central spoiler which is very efficient.

[mwraight]

Of course, in the real Beechcraft Bonanzas, which utilize the V-Tail, there have been numerous 'tail flutter' accidents, leading to fatal crashes.

Most of those flutter incidents and crashes occurred b/c the aircraft was flown over the Vne (never exceed speed). Flutter is commonly encountered when you exceed the design specifications of an aircraft. Ask anyone who's flown a sparless Zagi! The flutter does come from the torsion applied to the surface at high speeds, but for our purposes and speeds it's not a primary concern - unless you plan on doing straight down speed dives!

A V-tail has a certain simplicity to it and is elegant looking, but as for whether its any better or worse than a T-tail or conventional tail aircraft remains to be seen or proven. I've seen a lot of V-tail R/C planes and not one of them has had a problem with flutter or needed a reinforced mouting. I'm getting ready to build a 3.3 meter wingspan glider with and 18 inch V-tail, and I have no worries that it will perform flawlessly!

[daveWCO]

I'm getting ready to build a 3.3 meter wingspan glider with and 18 inch V-tail, and I have no worries that it will perform flawlessly!

I vote for an inverted V-tail.

[Sparky Paul]

Mr. Harik,
I would disagree with you for the very reasons that Andy specified for the "T-Tail!". V-Tail, often referred to as 'ruddervators', can cause a high torque, or torsional twisting effect along the rear fuselage, and can cause significant damage, or has happened in real life many times, seperation of the tail of the aircraft from the fuselage. ...

Gary
.
"torque"... Kinda like this.... :D
More noticeable with right aileron than left.
Ground tests show the same.
A thicker boom is indicated... :)

[mwraight]

I vote for an inverted V-tail.

Yeah, that would look cool. It appears Sparky Paul almost had an inverted V-tail!

Did the boom actually twist or was it the mounting to the boom?

[Sparky Paul]

It really twists like that!
I won't twist it that much by hand, MOF.
In any turbulence, it wiggles around a lot!
Here's a sequence thru a roll..
The boom is .25" CF, with 1/8"x1/4" spruce stiffeners along the tube.. the new version will use .315" CF.

[mwraight]

Wow...and it's carbon fiber too. It must be taking some good force. Does it twist in both directions? If it does my first thought would be that one side has a higher angle of attack than the other... I'll have to build my big V-tail with a lot of care. If you find a cause for the twist let me know.

The boom on the plane I'm building is aluminum...and I think it's about 1/2" in diameter. I'm not sure what the wall thickness is. The tube is actually some sort of cheap clothes-line they sell at Ace Hardware, but it's light and sturdy and has proven itself quite well. I'll have to post some pics when I get to building it - but right now it's just foam and a fiberglass fuse --- and I have no digital camera!

Michael

[daveWCO]

Michael:

I'll bring my Sony Mavica digital camera to the slope tomorrow if you want to borrow it. Some build picts would be cool.

daveWCO

[mwraight]

I'll bring my Sony Mavica digital camera to the slope tomorrow if you want to borrow it. Some build picts would be cool.

I agree. I shall have to start my own Giant Impulse build thread - and my "special project" as well. I'm going to start the Giant Impulse some time this coming week.

Giant impulse should have rudder/elevator/ailerons/flaps and spoilers.