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Author Topic: V-tail Aerodynamics  (Read 24149 times)

Offline Tim Wescott

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V-tail Aerodynamics
« on: April 19, 2011, 03:28:22 PM »
I'm getting a bit of flak from a fellow club member about the V-tail on my Waiex.  After discussion, he feels that the tail shape is going to make big differences in the flying qualities of the airplane, and was questioning the wisdom of such innovation on a beginner's airplane.  I kinda figured that a tail that flat (20 degrees) is primarily going to affect the aesthetics of the airplane.  Frankly, in my humble opinion, if he were going to complain (I'm gonna hear about this, because I know he lurks here) he should be after me for the slanted wing tips and the untapered wing with untapered flaps.

So, what do y'all think?  I know that a very young looking Dennis Adminson had some good things to say about V-tails in a 1980 Flying Models construction article ("Orange Crate", November 1980) -- but it was in the context of abandoning them because he was getting 'bad vibes' from judges that didn't feel they could see the plane correctly because of the tail.  I certainly don't see a lot of planes with V tails -- but the biggest argument that I could see against them is that they may be prone to rolling in gusty wind conditions, and (a) I've got those dang slanted tips and (b) my flying looks like it's in a gusty wind even when it's dead calm, and not just with that airplane!

I do need to get that plane into the hands of a competent pilot...
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Offline Randy Powell

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Re: V-tail Aerodynamics
« Reply #1 on: April 19, 2011, 04:05:07 PM »
I don't know. Dennis's last plane was a V-Tail too as were several others he built.
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Online Brett Buck

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Re: V-tail Aerodynamics
« Reply #2 on: April 19, 2011, 11:39:18 PM »
I'm getting a bit of flak from a fellow club member about the V-tail on my Waiex.  After discussion, he feels that the tail shape is going to make big differences in the flying qualities of the airplane, and was questioning the wisdom of such innovation on a beginner's airplane. 

     On the other hand, the subtleties of whatever bad it might do probably don't matter to a beginner, either. I think that the mild V-tail has negligible negative effects and I wouldn't worry about it. No offense, but it's probably got any number of other trim and power issues that will wash out whatever difference the V-tail makes. It's not just you, and it's not because you are a beginner - almost nobody at any level gets the airplane sorted out well enough to actually tell the difference of various design features.

     Brett

Offline Air Ministry .

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Re: V-tail Aerodynamics
« Reply #3 on: April 20, 2011, 12:00:48 AM »
Look on the ' electrickery ' bit. Hes still doing em .

These aerodynamisists say the side elevation is equal to the Vertical Stab area.

So rather than having 3 bits back there theres only 2 , y1

what they dont realise ?? is the stab is usually out of the flap / wing wash , in the majority.
or never entirely in it , as a flat one may be.
So theoretically its less bumpy and more smoother , when turning hard, and at other times . ~^ :!

Full size reports on Beaufighters , which had both types depending on type,tho with a fin ,
said Control Loads were higher ( more feedback ?) and longitudeinal stability increased ,
as they were hopeing. Both presumably advantages , as theres not excessive strength
needed on a C/L stunter ?. #^

Or as Adaminson says when they dont believe they fly better , It must just be that he's a better Pilot ! n~

Offline Tim Wescott

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Re: V-tail Aerodynamics
« Reply #4 on: April 20, 2011, 01:33:12 AM »
     On the other hand, the subtleties of whatever bad it might do probably don't matter to a beginner, either. I think that the mild V-tail has negligible negative effects and I wouldn't worry about it. No offense, but it's probably got any number of other trim and power issues that will wash out whatever difference the V-tail makes. It's not just you, and it's not because you are a beginner - almost nobody at any level gets the airplane sorted out well enough to actually tell the difference of various design features.
No offense taken -- I'm am a beginner at this.  I'd build something more in the common way, but I'm pathologically unfit to build to other people's designs -- this is just the evidence.  I kind of threw the design together by spreading out a half a dozen Flying Models magazines and comparing stunters.  Then I deliberately applied some features that aren't seen on any serious stunters at all (constant chord, and those wing tips) to make it look like a full scale airplane that isn't designed to fly upside down.  Having it end up being the most brilliant possible aerodynamic combination is beyond possibility (although if I put some thought into it I could probably spin a line of BS about how the slanted tips lift the wing the same amount as the V tail in a side gust, with each counteracting the rolling tendency of the other -- nah).

It certainly seems to corner more sharply and with more panache than my Skyray, but whether that's because of anything that I've done, or just because it's a few ounces lighter with the same span, or just because it's my baby, I can't say.  I do expect that I'll outgrow it, and when I do you'll see me flying something much more conventional in layout (although maybe with a V tail -- I like 'em).
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Offline Air Ministry .

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Re: V-tail Aerodynamics
« Reply #5 on: April 20, 2011, 04:46:36 AM »
Viva La Differance .

sounds like you used your intuition.
Intuition is the closest link to god .
Are you trying to say He messed it up .
Might work better than you think.
Have Faith .

Cant have just the paint jobs differant . %^@ H^^

Offline Randy Powell

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Re: V-tail Aerodynamics
« Reply #6 on: April 20, 2011, 12:02:22 PM »
Whatever the aerodynamic differences are, one thing is certain. V-Tails are cool.
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Offline Mark Scarborough

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Re: V-tail Aerodynamics
« Reply #7 on: April 20, 2011, 12:10:14 PM »
so are anhedryl wings!!!!
just sayin,,,,,,,,,,,,,, D>K
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Offline Tim Wescott

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Re: V-tail Aerodynamics
« Reply #8 on: April 20, 2011, 12:14:36 PM »
so are anhedryl wings!!!!
just sayin,,,,,,,,,,,,,, D>K
I came so close to putting dihedral on the Waiex, just because I think a plane with dihedral looks a lot better than one with a straight wing.  I finally talked myself out of it by thinking of the extra work on the wing structure.  Anhedral is the same thing -- it just looks more cool coming around the circle.

Flat wings and flat stabs just look so -- flat.
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Offline Mark Scarborough

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Re: V-tail Aerodynamics
« Reply #9 on: April 20, 2011, 12:30:22 PM »
Just for clarification, dihedral, anhedral, both serve a purpose, they aren't just for looks, though looks may be enough to design the rest of the plane around it. dihedral and anhedral both allow the leadouts to get up onto the vertical CG,,Just for clarification,,
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Offline Tim Wescott

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Re: V-tail Aerodynamics
« Reply #10 on: April 20, 2011, 01:48:56 PM »
Just for clarification, dihedral, anhedral, both serve a purpose, they aren't just for looks, though looks may be enough to design the rest of the plane around it. dihedral and anhedral both allow the leadouts to get up onto the vertical CG,,Just for clarification,,
Well, either the dihedral/anhedral serves to put the lines at the right vertical position with respect to the aircraft CG, or you have to move the wing root up or down to accommodate the bend.

Which you want to call 'chicken' and which 'egg' is up to you, but you certainly have to get the vertical CG and the line exits matched up.

On the Waiex, the prototype has the wings at the bottom and dihedral -- I could have done that.  Instead I chose a flat wing -- which meant that I had to diverge from the prototype in a visually significant way.  But it also meant that I didn't have to build a bent wing, I didn't have to worry about lucky boxes in the flaps, and I didn't have to worry about the effect of dihedral on the performance of the plane in the maneuvers.
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Offline Howard Rush

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Re: V-tail Aerodynamics
« Reply #11 on: April 20, 2011, 02:42:28 PM »
Just for clarification, dihedral, anhedral, both serve a purpose, they aren't just for looks, though looks may be enough to design the rest of the plane around it. dihedral and anhedral both allow the leadouts to get up onto the vertical CG,,Just for clarification,,

http://www.clstunt.com/htdocs/dc/dcboard.php?az=show_topic&forum=103&topic_id=287401&mesg_id=287401&listing_type=search#287477
See post #7.
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Offline Randy Powell

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Re: V-tail Aerodynamics
« Reply #12 on: April 20, 2011, 03:58:59 PM »
>>ust for clarification, dihedral, anhedral, both serve a purpose, they aren't just for looks, though looks may be enough to design the rest of the plane around it. dihedral and anhedral both allow the leadouts to get up onto the vertical CG,,Just for clarification,,<<

Of course, but just because something has utility doesn't mean it can't look cool, too.
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Offline Mark Scarborough

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Re: V-tail Aerodynamics
« Reply #13 on: April 20, 2011, 05:29:39 PM »
Thanks Howard,, as always your unique insight adds a certain level of respect to our meager conversations regarding design,, which reminds me,, I need to pay my royalties to Messerschmidt for the use of the 109 design,, sigh,,

Tim for future reference, lucky boxes are not required for small amounts of dihedral,, up to say an inch at the tips, My 109 doesn't use them and the controls have a VERY slight spring to them, but its only noticable if you look for it. building a dihedral wing is actually only one step more involved than without dihedral,
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Offline Chris Wilson

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Re: V-tail Aerodynamics
« Reply #14 on: May 02, 2011, 10:37:28 PM »


Tim for future reference, lucky boxes are not required for small amounts of dihedral..........
[/quote]

I think that this goes for a slight sweep forward of the trailing edge also.
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Offline Archie Adamisin

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Re: V-tail Aerodynamics
« Reply #15 on: July 23, 2011, 08:14:40 AM »
As the pilot of a few V-tail stunters, let me tell you all the secrets I learned.

Build it straight, build it light, and have a blast with it.

My Gemini I flew at the NATS from 1989 thru 1991.  It was published in Flying Models Aug 91.  It had a 620sq in 62in wing and a 22% tail (137sq in) flat.  It had a 120 deg V.  The tail was set 1/2" above the thrust line.  The wing was set 1" below the thrustline.  No Dihedral.  Moments were 11 (nose) x 12 (wing root) x 12 x 6.5 (18.75 crack to crack).  Wing and tail were both set @ zero incidence and controls were 1.5:1 elevator to flap. 

The Gemini flew very neutral and turned tight/equal in both directions.  Corners were crisp and tracking was very good in rounds.  Line tension was very good in all attitudes.

I have also had similar results in my R/C Pylon birds specifically Q-500's.  These not only offer lower interference drag for racing, they have better rudder authority on takeoff and better tracking through the flight with less tendency for tail wag.  They also fly well doing aerobatics.  This is where the reference is justified to apply back to CL. 

Some may also remember the Gemini III I flew in 1992.  This had a 30deg anhedral tail and it flew very much the same as Gemini I.  It did look more conventional as it had a rudder making the side profile look more typical.

So in regards to the Waiex, I would suggest building the V-Tail @ 120 deg.  This offers better rudder effect to reduce tail wag in hard corners.  It would also offer more line tension as the rudder effect would be greater with more dihedral.  Don't treat it any different than a normal stunter.  Make sure that you have equal throws, the tail is mounted @ zero incidence and aligned properly, and you will have a very nice airplane!! 

Archie Adamisin
Muncie, IN
Archie Adamisin
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Offline Tim Wescott

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Re: V-tail Aerodynamics
« Reply #16 on: July 23, 2011, 11:54:11 AM »
Thanks Archie.  That Gemini article was part of what gave me confidence to go ahead and build this thing.  If I build another one I'll try putting in more side area in the tail -- although that rear fuselage has quite a bit of height to it, and should lend some rudder action as well (the Waiex is billed as a 'Y' tail by it's designer, has the same deep fuselage, and actually puts a stub rudder on the end of the fuse).

The plane does fly well, as far as I can tell without putting it in the hands of an expert.  Unfortunately, the locals won't touch it and I haven't had a chance to get it into the hands of someone who can fly and will evaluate it for me.  I keep getting urged to not mess with V-tails, or flapped planes, or my own designs, etc. until I'm a more proficient flyer.  Yet every time I go back to my Skyray it just doesn't fly as well as that Waiex, so I keep gravitating back to the 'weird' plane.

(In fact, after I started getting flak from local flyers I went back to FM to see if you had published any other planes -- and you had!  A conventional tailed one, that you built because you were getting so much resistance to V-tailed planes.  Go figure).
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Offline Archie Adamisin

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Re: V-tail Aerodynamics
« Reply #17 on: July 23, 2011, 04:31:24 PM »
Tim,

Thanks for reading and enjoying the article.  I wrote it when I was 16.  I am glad that it helped to nudge you into the way of at least trying it.

Never shy away from trying something different.  Even if it dosen't work, think of all you can learn from your experiment.  You will never beat anyone trying to copy what they do.  They know their system and will always be one step ahead of you.  Learning for yourself by trial and error is the biggest reason I enjoy this hobby.  One of the things I love to hear is "That will never work" or "You can't do that".  No better motivation than that. 

Can't wait to hear about your progress.  Nothing better than trying something different. 

Archie Adamisin
Muncie, IN
Archie Adamisin
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Offline Dennis Adamisin

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Re: V-tail Aerodynamics
« Reply #18 on: July 24, 2011, 01:46:11 PM »

Build it straight, build it light, and have a blast with it.


Archie Adamisin
Muncie, IN

HOLY CRAP!   :o  You are giving away the family secrets!!!   :X  n~ HB~>  S?P  VD~  LL~  LL~  LL~
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Offline Chris Wilson

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Re: V-tail Aerodynamics
« Reply #19 on: July 24, 2011, 08:37:39 PM »
As the pilot of a few V-tail stunters, let me tell you all the secrets I learned.

Build it straight........

Ok, can anyone else see the conflict in the above?  :)
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Offline Air Ministry .

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Re: V-tail Aerodynamics
« Reply #20 on: July 24, 2011, 08:52:50 PM »
  I keep getting urged to not mess with V-tails, or flapped planes, or my own designs, etc.

 Thats called a ' Herd ' mentality.  S?P

 Youre obviously on your way to becomeing a misfit ,
 A social outcast , probably a recluse .

 Just look at Howard Huges .                   LL~

Offline Archie Adamisin

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Re: V-tail Aerodynamics
« Reply #21 on: July 25, 2011, 10:18:52 AM »
I didn't say flat, just straight! VD~

Archie Adamisin
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Archie Adamisin
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Offline Howard Rush

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Re: V-tail Aerodynamics
« Reply #22 on: July 25, 2011, 10:09:22 PM »
HOLY CRAP!   :o  You are giving away the family secrets!!!   :X  n~ HB~>  S?P  VD~  LL~  LL~  LL~

Speaking of family, I requested an Adamisin family tree from Big Art at the Nats.  I think y'all ought to get to work on that before you lose track.  Maybe you could publish it as a supplement to the PAMPA directory.
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Offline Archie Adamisin

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Re: V-tail Aerodynamics
« Reply #23 on: July 27, 2011, 05:37:49 PM »
Speaking of family, I requested an Adamisin family tree from Big Art at the Nats.  I think y'all ought to get to work on that before you lose track.  Maybe you could publish it as a supplement to the PAMPA directory.

Wow Howard, I think we ought to stick to something less confusing or easier to explain like V-Tails!!!   n~ n~ LL~ LL~

Archie Adamisin
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Archie Adamisin
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Offline Tim Wescott

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Re: V-tail Aerodynamics
« Reply #24 on: July 27, 2011, 09:17:45 PM »
Speaking of family, I requested an Adamisin family tree from Big Art at the Nats.  I think y'all ought to get to work on that before you lose track.  Maybe you could publish it as a supplement to the PAMPA directory.
Isn't it something like:

If PAMPA were NASCAR
then Adminson would be Unser.

?
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Offline Air Ministry .

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Re: V-tail Aerodynamics
« Reply #25 on: July 29, 2011, 07:24:19 PM »
If we lost the mufflers at comps and it was organised along those lines ,
stunt would become a spectator sport with a paying support group and
be on the increase . Now WHERE is the entrepeneur . VD~

as in ' N.A.S.C.A.R. ' noise and action is what they want , two schools
of thought.No Use being an Apologist, Just needs the Right Presentation.

Night races (long distance) for Goodyears on 60 ft. lines , too . . . :! H^^

Offline Tim Wescott

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Re: V-tail Aerodynamics
« Reply #26 on: July 29, 2011, 07:59:04 PM »
If they can make curling interesting an Wide World of Sports, surely they could do something with control line events.
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Offline Air Ministry .

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Re: V-tail Aerodynamics
« Reply #27 on: July 30, 2011, 04:16:00 AM »
As long as they dont use a blathering twerp like Murry Walker for a Comentator . n~ n1 H^^

Offline Larry Cunningham

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Re: V-tail Aerodynamics
« Reply #28 on: December 17, 2011, 02:32:42 PM »
I'm not sure of aerodynamic advantages or disadvantages, but V-tails are definitely cool. Maybe one of those 120-degree anhedral vees with a vertical rudder, a la F4C Phantom? Visualization of a simple model airplane mechanical elevator linkage always drove me nuts, but electronic servos would elegantly solve that (and perhaps allow us to "tune" out any weirdities, perhaps even program in some special advantage for CL stunt application).

And if a 120-degree empanage would be interesting and attractive, why not more? Say 72-degree pentagonal, with a vertical a keel rudder? If it worked at all you could psych out your competitors (except grizzled old farts who know better). ;->

L.

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Offline Shultzie

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Re: V-tail Aerodynamics
« Reply #29 on: December 18, 2011, 10:59:05 AM »
My latest V tail!!!! HB~> n1
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Offline Randy Powell

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Re: V-tail Aerodynamics
« Reply #30 on: December 18, 2011, 01:21:20 PM »
Yea, Don. Great. You couldn't just fly it out, could you?
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Offline Shultzie

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Re: V-tail Aerodynamics
« Reply #31 on: December 18, 2011, 01:34:45 PM »
Yea, Don. Great. You couldn't just fly it out, could you?

RIGHT ON!
U KNOW...THAT I HAVE WONDERED THE SAME THING EVER SINCE?...(that being sad and dung done...I should have been WAAAY MORE CAUTION...NOT ONLY DUE TO THAT SICK MOTOR RUN...BUT FORGETTING TO KEEP MOVING &  STEPPING BACKWARDS...TO IN ATTEMPTING AVOID THAT DEAD CALM AIR & TURBULANCE..THAT 4TH COFFIN CORNER OF THE HORZ. 8!
OUCH! n1 ~^
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Offline PerttiMe

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Re: V-tail Aerodynamics
« Reply #32 on: December 18, 2011, 02:11:03 PM »
so are anhedryl wings!!!!
just sayin,,,,,,,,,,,,,, D>K
So, an anhedral wing and V tail in the same airframe should be REALLY cool!
I built a Blue Pants as a kid. Wish I still had it. Might even learn to fly it.

Offline Chris Wilson

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Re: V-tail Aerodynamics
« Reply #33 on: December 18, 2011, 03:30:28 PM »
Come to think of it weren't there Russian stunters with tilted flat tailplanes? (Kinda like a poor mans Rabe rudder in operation.)

So perhaps there is a whole load of good in a properly tuned V tail design if its meant to combat gyroscopic procession.
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Offline rustler

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Re: V-tail Aerodynamics
« Reply #34 on: December 19, 2011, 04:27:08 PM »
...perhaps there is a whole load of good in a properly tuned V tail design if its meant to combat gyroscopic procession.

What an idea. Souds like something that might work. I'll get our tame mathematician onto it.
Ian Russell.
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Offline Chris Wilson

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Re: V-tail Aerodynamics
« Reply #35 on: December 19, 2011, 04:36:09 PM »
I'll get our tame mathematician onto it.
Do you happen to know of one?
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Offline rustler

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Re: V-tail Aerodynamics
« Reply #36 on: December 20, 2011, 01:25:32 PM »
Do you happen to know of one?

Our Club Prezz. Recently retired senior lecturer in engineering mechanics, Open University.
I recommend his recent (2005) book The High-Performance Two Stroke Engine, ISBN 1 84425 045 8. The pity here is that the publisher made him take out all reference to engines below 20cc, but still a good read.
Also has published books on vehicle suspensions and tyres, and shock absorbers.
Ian Russell.
[I can remember the schedule o.k., the problem is remembering what was the last manoeuvre I just flew!].

Offline John Hammonds

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Re: V-tail Aerodynamics
« Reply #37 on: December 20, 2011, 02:29:33 PM »
Do V tails require different throws in each direction? Just wondering if the fact that you re "compressing" the airflow in one direction (Towards the fuselage) or diffusing it in the other makes any noticeable difference to the efficiency? Would it be like having tip fins on the top or bottom of a tail only?

I've no idea, just asking...  :)

TTFN
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Offline Chris Wilson

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Re: V-tail Aerodynamics
« Reply #38 on: December 20, 2011, 02:47:01 PM »
Do V tails require different throws in each direction? Just wondering if the fact that you re "compressing" the airflow in one direction (Towards the fuselage) or diffusing it in the other makes any noticeable difference to the efficiency? Would it be like having tip fins on the top or bottom of a tail only?

I've no idea, just asking...  :)

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Hi John,
            no idea here really but the key would seem to be a 'noticeable' difference beyond what the human body could readily adapt to  ............ and I suspect that there would not be one if the included angles are close to 180º.

(But I am curious about using the intended asymmetry as a tuning tool to combat gyroscopic precession though!)
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Offline Tim Wescott

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Re: V-tail Aerodynamics
« Reply #39 on: December 20, 2011, 03:45:46 PM »
Do V tails require different throws in each direction? Just wondering if the fact that you re "compressing" the airflow in one direction (Towards the fuselage) or diffusing it in the other makes any noticeable difference to the efficiency? Would it be like having tip fins on the top or bottom of a tail only?

I certainly didn't notice that effect on mine.  If anything, I think it would have a far greater effect in the amount of drag produced by the tail than in a differential lift of the tail.  And since the tail's induced drag is probably miniscule compared to the whole airplane -- I think you could safely disregard it unless you're a way better flyer than me.
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Offline John Hammonds

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Re: V-tail Aerodynamics
« Reply #40 on: December 20, 2011, 05:21:51 PM »
Hi Chris, Tim,
Yes that's what I figured. I'm sure there is some effect but as you say unless we're taking the angle of the "V" to the extreme someone of my ability at least would not expect to notice any difference. The reason I asked was Like Chris questioned, could it be used to trim out other effect. He mentioned Gyroscopic Precession I was just simply thinking about the effects of drag above as opposed to below the thrust line due to U/c and the like. I admire Tim for taking the plunge and running with his own design, I've Plan bashed a few but always left the aerodynamics well alone.

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Offline Tim Wescott

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Re: V-tail Aerodynamics
« Reply #41 on: December 20, 2011, 05:43:41 PM »
Well, I can say with authority that the V-tail does not compensate well when you're at 45 degrees, going straight up, and the engine suddenly quits.

But then, neither do conventional tails.
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Offline Larry Cunningham

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Re: V-tail Aerodynamics
« Reply #42 on: December 20, 2011, 06:28:04 PM »
Does anyone know the aerodynamic reasons for using the V-tail on the Beech Bonanza? I've always been curious.

I flew one (full sized) and it didn't feel any different to me, but I'm not a very sophisticated pilot. I know the Doctor Killers are quite fast and efficient, if a bit hot to land. I don't think that was caused by the V-tail, but rather the wing design.

Also I seem to recall seeing some significant dihedral on a canard, but I might be thinking of the fore-aft swing on at least one exotic SST. Airliners seem to commonly have dihedral on the tail plane.

I have a feeling the traditional stabilization features associated with dihedral on a wing (roll stabilization?) have little or not bearing on its use on elevators. I'm probably wrong, frequently are, and almost never admit it.

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Offline Tim Wescott

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Re: V-tail Aerodynamics
« Reply #43 on: December 20, 2011, 09:42:30 PM »
Does anyone know the aerodynamic reasons for using the V-tail on the Beech Bonanza? I've always been curious.

I flew one (full sized) and it didn't feel any different to me, but I'm not a very sophisticated pilot. I know the Doctor Killers are quite fast and efficient, if a bit hot to land. I don't think that was caused by the V-tail, but rather the wing design.
Somewhere I remember reading that for a while it was felt that a V-tail had lower drag, because you've only got interference drag from two surfaces instead of three, but that in reality the difference isn't that great, and for most purposes the decrease in drag isn't worth the difficulty of independently tuning the horizontal vs. side area.

I think the biggest reason for the V-tail is the same reason that I put one on mine: it just looks kewl.
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Re: V-tail Aerodynamics
« Reply #44 on: December 20, 2011, 11:10:09 PM »
Does anyone know the aerodynamic reasons for using the V-tail on the Beech Bonanza? I've always been curious.

I flew one (full sized) and it didn't feel any different to me, but I'm not a very sophisticated pilot. I know the Doctor Killers are quite fast and efficient, if a bit hot to land. I don't think that was caused by the V-tail, but rather the wing design.

Also I seem to recall seeing some significant dihedral on a canard, but I might be thinking of the fore-aft swing on at least one exotic SST. Airliners seem to commonly have dihedral on the tail plane.

I have a feeling the traditional stabilization features associated with dihedral on a wing (roll stabilization?) have little or not bearing on its use on elevators. I'm probably wrong, frequently are, and almost never admit it.

L.

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The V tail was designed  back in the 30s by a Polish engineer, I have flown and been in both Beech Bonanza V and 3 tail, I like them both, the V tail has a dutch roll, the conventional Bonanza flies better in my opinion. Beech also had a problem with the tails falling off the V series... They say the V tail puts more stress on the back of the fuse..
That may have been why Beech went away from them.
Now  if you want something cool  the X tail  is the bommb

Randy

Offline Mike Scholtes

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Re: V-tail Aerodynamics
« Reply #45 on: December 21, 2011, 11:04:22 PM »
Having some experience in the matter I feel compelled to speak up in defense of the Bonanza, both V-tail and conventional. The story that the V-tail was adopted to reduce drag in what was intended from the outset as a fast and sleek retractable is apparently valid. It is also true that the V-tail wanders a little compared to the straight tail models, especially the earlier versions with shorter fuselage and lack of ventral fin. All Bonanzas are a pilot's joy to fly, like an extension of your mind rather than driving a truck like some of the heavier Cessna singles. The earlier V-tails could shed the leading edge of the stab when pressed into a high speed dive, usually a spiral dive after losing orientation in instrument conditions by non-instrument-rated pilots. This flaw was remedied by an STC early on, a cuff that fixed the LE sheeting to the fuselage and prevented it peeling back at 250 knots. This misuse of the aircraft is what gave rise to the moniker "fork tailed doctor killer," doctors reputedly being overconfident. The landing requires attention, like in any high performance aircraft, but the airfoil is not a supercritical section like say the C-310 or (different league) P-51. Wonderful airplane. Just the sight of a V-tail climbing out and pulling up the gear brings tears to my eyes.

Offline Tim Wescott

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Re: V-tail Aerodynamics
« Reply #46 on: December 21, 2011, 11:06:55 PM »
Just the sight of a V-tail climbing out and pulling up the gear brings tears to my eyes.
I love those airplanes.  The Waiex almost ended up being a Bonanza -- there may be a Bonanza semi-scale in my future.
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Offline Mike Scholtes

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Re: V-tail Aerodynamics
« Reply #47 on: December 21, 2011, 11:17:12 PM »
Go for it! The planform of the Bonanza is already pretty good (similar to the beautiful Bellanca pictured on this forum recently). I built a Brodak Stinger V-tail for OTS a couple of years ago and it stunted just fine. The mechanics of getting the halves of the V to move equally was tricky and I ended up modifying the control linkage a few times. But it worked, and with some better design thinking from the outset, no reason why a V-Tail Bonanza would not be successful, at least within the limits of keeping it looking like a Bonanza and not a Trivial Pursuit with a bent stab.

Offline Dennis Adamisin

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Re: V-tail Aerodynamics
« Reply #48 on: December 22, 2011, 09:06:15 PM »
Somewhere along the line you stop theorizing & rationalizing and hunker down and do it...
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Offline Mike Scholtes

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Re: V-tail Aerodynamics
« Reply #49 on: December 22, 2011, 10:02:31 PM »
Now THAT'S what we're talkin about!

Offline Tim Wescott

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Re: V-tail Aerodynamics
« Reply #50 on: December 22, 2011, 11:09:10 PM »
The mechanics of getting the halves of the V to move equally was tricky and I ended up modifying the control linkage a few times.
I just used a pair of lucky boxes on the elevators, and made sure that the center of the control horn was firmly nailed down by a good bearing, and everything worked just fine.

I did have to purpose-make the control horn, with the ends angled out instead of straight, but that was no big deal.
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Offline Robert Dible

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Re: V-tail Aerodynamics
« Reply #51 on: January 16, 2013, 08:02:28 AM »
An interesting thread on V-tails, but it seems a little short on the actual design theory.  What this set of formulas and relationships does is to provide a guide for converting a conventional tail to an equivelent V-tail.  While I originally researched it for use in RC pylon, where everyone just copied from other designs and the first guy just used what glider guiders used.  The flatest I've flown was 130 degrees which had great performance in the air, but failed to give any ability to alter course on landing where you need to miss other airplanes, so I ended up at 120 degrees.  The angle on a Beech Bonnaza is 118 degrees, BTW.
__________________________________________________________________________

Measure the areas of the original design's vertical and hoizontal surfaces.

A lot of sport models use about 1/3 of the horizontal area for the vertical area. To figure the angle the following example shows the basic math for such a ratio.

Once the ratio of vertical to horizontal surface area is determined, it becomes a simple math problem to calculate the angle of the V, as well as the area.

The basic trigonometric function is : Sin^2  + Cos^2  = 1

{This should read Sine squared Theta + Cosine squared Theta equals one}

If we want the ratio to be 1:3, then Theta () needs to result in:
0.25 + 0.75 =1

The square root of 0.25 is 0.5, and the square root of 0.75 is .866

The arc-sine or inverse of the sine function of 0.5 gives 30 degrees.
The arc-cosine or inverse of the cosine function of .866 also gives 30 degrees.

Thus, for an equivalent ratio of 1:3 for the vertical to horizontal area, the angle of each half of the V-tail need to be 30 degrees above the horizontal plane. Since the angle between the V is typically called out, it becomes 120 degrees (180 – 2(30)).

There is some disagreement as to the area required. They range from:
a) using the same size as the existing horizontal stab area
b) using the projected stab area of the V the same as original
c) using the same total area as the combined area of the original tail
d) using the square root of the sum of the squares of areas of the vertical and horizontal

Gliders often use very acute angles (90-110 degrees), because they need a lot of rudder authority.
Pylon racers often use (110-120), I’ll reserve comment as to why.


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Offline Tim Wescott

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Re: V-tail Aerodynamics
« Reply #52 on: January 16, 2013, 09:13:33 AM »
An interesting thread on V-tails, but it seems a little short on the actual design theory.

Given my actual question, I should maybe have titled the thread "V-tailed performance potential"

There is some disagreement as to the area required. They range from:
a) using the same size as the existing horizontal stab area
b) using the projected stab area of the V the same as original
c) using the same total area as the combined area of the original tail
d) using the square root of the sum of the squares of areas of the vertical and horizontal

Gliders often use very acute angles (90-110 degrees), because they need a lot of rudder authority.
Pylon racers often use (110-120), I’ll reserve comment as to why.

I made the projected side and top area of the V the same as the prototype.

Control line planes tend to have small vertical surfaces, so it makes sense to have a very flat tail.  The particular airplane that I was talking about in this thread has what the designer called a "Y" tail, featuring a tall rear fuselage with a movable rudder, in addition to the "V" tail.  So it ended up with very flat tail indeed.

I'm planning on revisiting the "V" tail thing at some point, now that I'm flying better.  Maybe I'll dig up all the Adaminson designs I can find in Flying Models.
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Offline Dave_Trible

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Re: V-tail Aerodynamics
« Reply #53 on: January 16, 2013, 11:52:44 AM »
A few years ago, in doing my best Adamisin act,  I took my airplane design of that time, Blue Moon, and took the flat stab and set it up in a 30 degree lift into a V tail on each side and called it Midnight Lace to go with the lace paint job.  I found no need to alter areas from the 23 percent I had on the flat tails. What WAS different was the huge handle bias needed to get turns equal both ways.  Once there I could perceive no flying differences in good air. I got many favorable comments on the ship but its downfall was in turbulent air the tail couldn't decide whether to be stab or rudder.  Even did a half barrel roll and back once at a Topeka contest on one of those crazy days at the OLD field.  If not for that I might be flying a V now.

Dave

3/9/13...way old thread I know but I just found an old photo of the above mentioned airplanes about '95-6.  Picture of a picture so sorry if it's not too good.
« Last Edit: March 09, 2013, 07:59:55 PM by Dave_Trible »
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Online Brett Buck

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Re: V-tail Aerodynamics
« Reply #54 on: January 17, 2013, 10:25:04 AM »
Somewhere along the line you stop theorizing & rationalizing and hunker down and do it...

  None of those could ever possibly work!

   Brett

Offline Jared Hays

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Re: V-tail Aerodynamics
« Reply #55 on: January 22, 2014, 10:10:49 AM »
My dad's profile V-tail Bonanza powered by a ST .40 flies great for a fun sport plane.



Offline Howard Rush

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Re: V-tail Aerodynamics
« Reply #56 on: January 22, 2014, 12:56:34 PM »
That looks cool, Jared.
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Offline Charles Hofacker

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Re: V-tail Aerodynamics
« Reply #57 on: June 08, 2015, 09:01:35 AM »
I would sort of think that a properly set up V-tail would be very similar to the infamous "wiggle" rudder. 

Offline Robert Zambelli

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Re: V-tail Aerodynamics
« Reply #58 on: June 10, 2015, 06:51:59 PM »
My Duetto was the best flying plane I ever designed.

Powered by a SAITO 30, it was stable, predictable and turned equally and effortlessly in both directions.
I was really amazed at how light the controls were.

Bob Z.


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