Dual elevator servos
 

Well I have finally came to the conclusion that when using two elevator servos unless you can get them mounted in the exact same spot on opposite sides of the fuselage you cannot get the two halves to move equally by just reversing one servo. I just finished the Funtana 90 and use a servo reverser and the two halves are off by 3 degrees at full deflection. I guess I am going to have to break down and by a matchbox as much as I hate to.:( Has anyone else had this problem and what did you do to fix it?

RE: Dual elevator servos
 

Get a good radio, and you will have no problem at all:D

RE: Dual elevator servos
 

I agree a raio with elevator mixing would be a great idea but my 7cap is fairly new and I hate to throw it out. But heck I could always use another radio

RE: Dual elevator servos
 

I have the 7CAP also. Its a good radio, but I plan to upgrade at the end of the season.
Do you have both servos plugged into different channels on your reciever?
Have you tried a reversing Y-harness? they are hard to find, but look around online.
both servos will run on one channel, and they will recieve the same signal.

RE: Dual elevator servos
 

I have a 7cap and had no problem setting up dual's on my cg yak. You have to use a p mix and slave channel 7 to 2 and change the switch to the stick on the tranny. it took a while to figure it out but you can do it.

RE: Dual elevator servos
 

I am having the same problem, I do know one thing, after hours of changing this and that to get the elevator halves the same, The longer rod on one side makes no difference in the deflection. If you have your servo arms exactly straight up on each side, It does not matter of the arm is 4 inches or 6 inches. the geometry difference is changed only in the servo arm length and the control arm length. I ran out of options and replaced both servos thinking that the problem was with them,...WRONG! I need help too. Right now I have the control rods in different holes (which is stupid) but the halves function closest this way. My plane flies great, the only time that I can tell is when the plane is at full elevator and it rolls to one side which I correct with the alerons. Help us you guys!

RE: Dual elevator servos
 

I agree. I think the H9 Funtana has a fundemental design error here. I've got a decent radio and I still can't get the elevators to move exactly together.
John

RE: Dual elevator servos
 

Hello guys,

check the site of Bob Pastorello, here a GREAT explaination of how to setup dual elevator servos. He speaks about JR 10x radio, but you don't have to look at the radio programming details - try to figure out the concept.

http://www.rcaerobats.net/DualElev.htm

IMHO the most important aspects often overlooked are:

- how to use subtrims
- control rod geometry

For those more interested in that important area, check also this great tutorial by Troy Newman, a GREAT pattern pilot:

http://www.centralhobbies.com/instru...s1/link03.html

For those even more interested :D, check all Troy articles about linkages by going there:

http://www.centralhobbies.com/instru...s1/link01.html


Let us know if the throws are still different ! ;)

RE: Dual elevator servos
 

Maybe you guys could try going old school and making your own hole in the control arm to adjust for the degree difference. Sure it wont be totally linear but this is a funtana were talking about, NOT an F3A plane.

In on the control arm for more deflection out for less.

RE: Dual elevator servos
 

Check out the equalizer II made by www.smart-fly.com

Cheaper than a matchbox or digital programmer. Easy to use, ingenious design. I have a futaba 7C running one of the EQII's inside a 1/4 cap. It has both my elevators matched exactly center and on endpoints with a pair of hitec 5645's.


Sean

RE: Dual elevator servos
 

I don't think equalizers are of any help when you have a mechanical problem...

First do the best mechanical setup that you can do, then you will have an almost perfect setup. It is meaningful the fact that f3a pilots don't use such instruments.

RE: Dual elevator servos
 

I still think it is a geometry problem since one pushrod is longer than the other the arc in which the control horn changes. I agree that it is only a small change but on a elevator this big it makes a huge differance. I have tried to mix the two halves but the trim only seems to work on one channel. Tom were you able to get the trim working on both the master and slave.

RE: Dual elevator servos
 

According to futaba site the 7c doesn't have the capability for trimming both elevator halves. Here's the link and the info from the futaba site:

http://www.futaba-rc.com/faq/faq-7c.html

Radio System FAQ
I am using a mix for Dual Elevator, but cannot figure out how to trim out my left elevator. If I use the trim button, it will of course trim my right elevator, but I get nothing from the left one. Is there some way around this?

Unfortunately, no, there is no way to set this up. While based in looks and style on the 9C it does not have all of capabilities of the 9C. To be able to trim your second elevator servo, we would suggest first that you of course do this by hand at the control surface, but if you still need to do a little more trimming you may of course go into your Subtrim menu to make further adjustments. But if you are wanting to trim in flight, you will need to purchase a Synchronizer.

RE: Dual elevator servos
 

I am having the same issue on my Skyshark Edge. I have narrowed it to the location of the control horns on the elevators. One is about 1/16" more to the rear of the hinge line than the other. I believe this is causing an offset at full deflection. The elevator halves are off about 1/4" at full down deflection only on high rates. I cannot see any difference at full up deflection on either high or low rates.

Dallen58

RE: Dual elevator servos
 

Man; this topic (trying to rig a dual elevator servo set-up with a 7C) has exploded the past week or so. You guys are finding out what I did when I got one last year; you just cannot do it without an extra piece of kit... equalizer, Y-harness, etc.

Since a 9Z is my primary radio, this was more annoying to me than anything else. But I feel for you guys who use the 7C as a primary. Makes you wonder WHY this "modern" feature was left off????

RE: Dual elevator servos
 

honostly i havn't tried yet. this is a new plane and i had to figure how to mach them up. but i think jon nailed it. only channel 2 will be able to be trimed in flight. oh well, guess i have to buy an equlizer this week end.

thanks for this thread though. i probably wouldn't have even relized it until it was to late[X(]

RE: Dual elevator servos
 

I ran into this last year, AFTER I boutht the 7C. It's really sad that this radio doesn't have this capability to reverse and trim both servos, but that's pure marketing more than anything.

I set up duallys on a Fliton Extra 330 with a reversing Y harness with adjustable trim pot. One elevator half is controlled by the radio, the other by the trim pot on the harness. Works great. I can't remember the brand, but it was only about $30.

RE: Dual elevator servos
 

I have pacific aeromodels edge 540t and laser 200, and in both setups they are calling for dual elevator servos, servo openings are staggered, one horn up, one horn down - from factory! (to avoid reverser) this will not be perfect at full deflection (the arcs have to be the same). My solution - dual elevator bellcrank (world models), made plates to cover openings and mount bearing flange, carbon fiber pushrod, 90 oz digital in regular servo bay. Should be dead nut as long as holes in elevator halves are accurate. We'll see.......
I'll post some picts later

Ted

RE: Dual elevator servos
 

The world models GS p51 works something like that. A pushrod runs from a single servo back to a rod below the stab. The rod goes thru the side of the fuse with basically wheel steering arms on each end, then a pushrod goes from there to the elevator... Seems to work pretty good..

http://www.rcuniverse.com/magazine/a...article_id=598

http://www.rcuniverse.com/magazine/r...or-linkage.jpg

RE: Dual elevator servos
 

can't gaurantee that i have found the answer but i was having the same problem and eventually convinced myself that the servos were faulty.

I removed the servos and set them up out of the plane so that i could measure the deflection and sure enough on full deflection (as needed on the funtana) there was a considerable difference between each servo (I am using jr 8425 servos not cheap).

I emailed my distributor who would gladly have looked into the problem but during our email correspondence he informed me that jr servos work like this. At 100% ATV the output shaft swings thro 60 deg and at 150% ATV the output shaft swings thro 90%. When i looked at my servos they were swinging through more than 100 deg (with 150% ATV) and that was my problem. I had installed one servo set it up for max ATV the other servo was set up exactly the same, one servo swings thro 100deg one servo swings thro 105 deg answer lower the atv to achieve the 90deg (or what each servo will swing thro) in my case this is 120%ATV then both servos will swing to the max they are designed to. Of course you may have to lengthen the servo horn. Hope this solves it for you as well

:D:D:D

RE: Dual elevator servos
 

I have just dealt with this same issue. With elevators centered, apply up elevator and the right side traveled further, 'higher'. Apply down elevator and the left elevator traveled further 'down'. Spent two evenings without any luck trying everything I could think of.
Good luck. Joe