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Mar 20, 2003, 07:57 PM
Husband, Dad, Skydiver, RC'r
Bill K.'s Avatar

QUESTION: V-Tail Setup/Mixing Question?


Hello,

I have a GYM-E with the V-Tail on it. I have my radio set to Delta wing because that's the setting that seems to be right. What I would like to know though is if it really is right. I have a JR 652 radio.

Here is what is happening when I give it stick inputs:

Left stick is my throttle:
   Up means go and down means stop.

Right stick:
   When I move the stick up both of the V-Tail control surfaces move down.
   When I pull the stick down they both go up.
   When I move the stick to the right, the right surface moves down and the left surface moves up. ??
   When I move the stick to the left, the right surface moves up and the left surface moves down. ??

All my training says that the left and right stuff is backwards. For example if this were alerons and the right one went down the plane would be turning LEFT, are the airodynamics backwards with a V-Tail? I don't see how they could be.

Thanks,
Bill
Last edited by Bill K.; Mar 20, 2003 at 08:12 PM.
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Mar 20, 2003, 08:23 PM
Registered User
columbiarcdude's Avatar
Quote:
Right stick:
When I move the stick up both of the V-Tail control surfaces move down.
When I pull the stick down they both go up.
When I move the stick to the right, the right surface moves down and the left surface moves up. ??
When I move the stick to the left, the right surface moves up and the left surface moves down. ??
I know it looks a little funny but this is correct for v-tail ruddervators. The way Todd explains it in the instructions is that they both "point" the direction of the turn.

You're going to really like flying your Gym-E

Tom
Mar 20, 2003, 08:44 PM
BEC
BEC
Registered User
BEC's Avatar
Think of the surfaces as rudders rather than ailerons. Then it makes sense. You have it correct. Enjoy your Gym-E. I enjoy mine!
Mar 20, 2003, 09:26 PM
Husband, Dad, Skydiver, RC'r
Bill K.'s Avatar

Thanks.


Thanks guys. I will trust you and go fly it this way, just goes against the grain

I hope to give it a madin flight tomorrow... Provided the winds are not blowing to bad...

The weather has been rainy all week...
Mar 21, 2003, 08:04 AM
Registered User
The way the controls on an aileron/V-tail aircraft should work finally made sense to me when someone said that the aileron control surface on each side should always move in the opposite direction as the V-tail control surface on the same side of the aircraft. That's why it's possible to control all 4 control surfaces with just 2 servos if you mechanically link each servo to move the front and rear control surface on each side to move in opposite directions whenever the servo is actuated. The first use I saw of this mechanical linking was on Todd Long's original V-tail Tiny.
Mar 21, 2003, 08:27 AM
Husband, Dad, Skydiver, RC'r
Bill K.'s Avatar

Learned by doing


Dave,

I finally got to fly it this morning. Must say it went against everything my mind was saying, however it works. Works great in fact. I was shocked at just how tight it can actually turn.

Based on your post below I am thinking that maybe I will build a tiny-x with a V-Tail config. That might be fun. Only need 2 instead of 3 servo's that way too. That keeps the cost down, which makes the wife happy...

I swear I learn so much on this place...

Thanks again,
Bill K.
Mar 21, 2003, 11:51 AM
Motor Maniac
An inverted V-tail will have the tail surfaces move in the same direction as the ailerons, so if you are thinking about linking ailerons to a V-tail this might be the way to go. The down-side of inverted V-tails is the susceptibility to damage on landing.
Mar 21, 2003, 12:47 PM
Husband, Dad, Skydiver, RC'r
Bill K.'s Avatar
Hmmm, had not thought about doing an inverted V. Might have to give that some thought though. Seems like some sort of a landing gear or wire could come down enough to protect the V somewhat?? Might be an interesting test to see if it can be done...
Mar 21, 2003, 01:55 PM
Live to ride... and fly!
Tres Wright's Avatar
I lost a V-tailed plane many years ago due to setting it up wrong. It's a long story, but I had successfully flown the plane many times before it happened. I switched transmitters and thought I had the servo direction correct, but alas, it was not to be I spent the whole flight trying to figure out which way to steer to correct the problem, but the plane kept circling one way, then the other which compounded my confusion. It ended in what appeared to be a soft landing over 100 yards away, but when I got to it I discovered the landing was not-so-soft Scratch one Thermal Charger!
Mar 21, 2003, 02:09 PM
Husband, Dad, Skydiver, RC'r
Bill K.'s Avatar
Ouch, bummer, bummer. I was just real glad that I posted and asked last night. I was just about to re-set it all up and that would not have been good. I would have been doing strange circles myself I have a feeling...
Mar 21, 2003, 02:40 PM
Registered User
Here's a link to a V-tail Tiny review that has a photo where you can get a general idea of the linkage. You don't really need an inverted V-tail to use this method of using 2 servos linked to both the aileron and V-tail control surfaces. I'll also include a link to a large gif image of the plan, which has more detail on the linkage.

http://www.rcmicroflight.com/dec99/tiny03.asp

http://www.rcmicroflight.com/plans/tiny/tiny_full.gif
Mar 21, 2003, 02:51 PM
Husband, Dad, Skydiver, RC'r
Bill K.'s Avatar
Dave,

In the first picture, are you using carbon tube for the control linkage? If so, how hard is that stuff to work with? What do you attach to the ends to connect to the control horn's etc? Second, are the two controls crossing as they go back or does the right servo control the right airleron and the right part of the V-Tail? It would seem to me like right servo would control both things on the right side and the one on the left would control the stuff on the left?

In the second drawing gif, is that to scale? Is the wing span really only 24"?

Thanks,
Bill
Mar 21, 2003, 07:29 PM
Registered User
Well, I didn't write the review, I didn't take the photo and it's not my aircraft. I just posted links to someone else's work. So I can't really tell you anything that you can't see in the pictures. I have a Tiny kit in my basement that I haven't gotten around to building yet. If it's like any of the other aircraft I've built, I'll probably make lots of running changes along the way. But I can't tell you what because I haven't gotten around to it yet!


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