V-tail questions

[OFS]

In a turn, does the tail act like ailerons, one up and one down or like two rudders both turning the same direction?
Thanks, OFS

[Andy W]

Yes.. (think about it)..
..a

[Sparky Paul]

To take some of the mystery out..
With the surface held with the tip up, as if it were a true vertical, the rudder should move exactly as you would expect a rudder to move.
Trailing edge left for left rudder....
http://www.rcgroups.com/cgi-bin/photopost/index.pl?photo=627
.
Sparky Paul
http://www.angelfire.com/indie/aerostuff
PJB's Seriously Aeronautical Stuff
http://home.earthlink.net/~pjburke1/aindex.html

[omega blood]

I was wondering about the same thing. does a v-tail roll or does it yaw? I just built (and crashed) a v-tail and it seems to roll ( and it did thus the crash) instead of yaw. Or is it just me.

[OFS]

Thanks for the replys, I had to move two envelopes to match Sparky Pauls pictures.Its still confusing. It doesn't seem normal.
Sparky Paul we are almost neighbors, I live a little north of Bishop.
Kevin

[BEC]

Yup, Paul's pictures match the way my Gym-E's tail works when it works correctly. And, of course, both trailing edges up for up elevator, both down for down elevator. Trying to think elevons leads you down the wrong path (which is why I had to reverse some things to get the Gym-E to go the right way :eek: )

[Sparky Paul]

There's a busted airplane or two in the past (sob!)that used v-tails set up "intuitively", and wrong.
For the inverted style going down from the boom, point the tip downwards to set the polarity.
.
Kevin, should be lots of places to slope up there!

[FlyByMike]

Speaking of incorrect setups, you definitely want "mixing" on :eek: (DAMHIK)

[member73]

Even a properly set up V-tail can introduce adverse roll. The tail moment should be significant enough to counteract it though and dihedral/polyhedral will help. I'm sure a short coupled V-tail with a straight wing would have some funny flying characteristics. An inverse V-tail (like on the preditor UAV) has the correct roll/yaw coupling, but having those tails pointing down can be a real pain on landing.

[kevin b berger]

I guess I have never had a V-tail, but I am coincidentally building one right now. I have a Zagi sloper, and my brain was figuring that the v-tail got set up the same as the elevons (or ailerons!). So you are telling me that the opposite is true?

I GREATLY appreciate your inputs, and looking forward to additional comments. Also, I was looking for the mentioned "pictures", and followed the links above, but could not find the photos.

Thanks, I think you have helped me avert a new plane disaster!

kbb

[Sparky Paul]

kbb, you should just have to click on the link in my message... the image is in the Gallery here..
.
odd that pasting the link from the previous message doesn't work!
http://www.rcgroups.com/cgi-bin/pho...ex.pl?photo=627
.
Does this?
http://www.rcgroups.com/cgi-bin/photopost/index.pl?photo=627
.
Yes.
The first link is exactly as copied from the message.. with the pho...ex
the 2nd has the full address, photopost/index filled in..
??

[kevin b berger]

Thanks, I checked the last 2-links, will have to check them out later, cause there is a lot of good looking stuff, I found the photo on the first link.

I am still shaking my head! Thanks for this post, and for the skilled, intelligent, knowledgeable responses!
kbb

[max z]

Trying to think elevons leads you down the wrong path

Unless you invert the V, then they are set up exactly as elevons. And if you then split the V and move both halves out they will work as elevons too :) :) !

[Sparky Paul]

Here's what upright (Bonanza) and inverted (Predator) look like for left rudder...
http://www.rcgroups.com/cgi-bin/photopost/index.pl?photo=812.
(pays to keep old parts around.)

[CharleyRexom]

I inverted the vee tail on my Mini Pleaser with very good results. The vee tail acts like ailerons when inverted so it helps roll into the turn. There have been no problems with damage to the tail hanging down with around 15 flights and lots of landings in the past 2 weeks. My .020 carbon tail skids are worn off, but the balsa seems to be holding up rather well. Of course, the key to my success is the light weight and slow speed. I would guess that any plane with a moderate wingloading and heavier would have problems with the tail on the ground. A slope ship with a belly full of lead would be a disaster!
But I really like the inverted vee on my Mini Pleaser!

Charley

[Sparky Paul]

BillM, your message vanished while I was running down this site..
For the best information on sizing a v-tail..
http://www.charlesriverrc.org/articles/design/markdrela_vtailsizing.htm

[Dave Bohling]

As long as we are talking about v-tails, has anybody experimented with v-tail differential? I read about it in the following article regarding programming the JR 8103 for sailplanes
<http://www.reddata.com/sass/soaring_info/techdocs/Programming%20the%20JRXP8103%20transmitter.doc>
The good part is at the end of the article.

Dave

[Gary Retterbush]

I normally end up with some "reverse differential" on my Vtails. That means I use more down than up. My Space 2000 turned like a wet rag until I finally got the darn thing programmed just right.