Hi all,

I have installed two Futaba 3010's in my funtana 90 elevator halves, one on each side. The problem I have is that one side is slighly faster than the other, but only when moving the elevators up. When moving down they seem to be the same speed. Obviously this will cause a slight roll to occur when quickly applying full up elevator, such as pulling a wall or parachute and I'm keen to sort this out. I was wondering whether this is likely to be a software problem with the mixing on my FF9 tx or whether the servos really are running at different speeds. Anyone come across this before and have any ideas on how tol fix it ?

I would have to start by checking the mechanical setup.

When programming the endpoints into your Tx. Both elev servos should end up identical. If you need to program more/less travel on one servo to achieve the same end points eg. 110% left servo and 90% right servo then you know that they are mechanically set up differently.
Check to make sure that both control horns are set on the hinge line. Then make sure the clevises are the same distance from the hinge line. Then make sure the servo arms are set to the same angle at neutral. All of these being right, your servos should move together.

Anybody else?

Edit: Do you have the servos on a Y with a reverser or are they run seperately to the Rx? I was assuming that they were pluged into the Rx seperately.

Thanks, the first thing I did was check they are mechanically set up the same and they are as spot on as can be, so I don't think that is the cause.

They are run separately on different channels and mixed on the tx, hence I asked whether it could possibly be a software fault, where the slave servo is running slightly behind the master servo in the tx software processing etc. ?

I know some radios like the 9ZAP has the facility to allow the servo speeds to be altered to fix problems like this, but I don't think my 9CAP (FF9) does. Maybe I could try a bit of exponetial on the faster servo to allow the slower one to catch up.

Have you tried swapping the servo's leads around in the RX. Does this make the other surface go slow instead?

If it does then it something to do with the TX/RX. If the slow surface stays on the same side then it is is the servo or the linkage causing the problem and not the TX/RX.

Nick

This may be the answer: [link=http://www.futaba-rc.com/faq/faq-8u-q594.html]Futaba FAQ[/link]

Thanks, interesting article on the second servo being slower on the Futaba site. I also seem to remember that one of the servos was reversed as well, which they suggest makes it even slower. So looks like it probably is in the mixing software

As suggested I'll check this out by swapping the leads over and see if the second (slaved) servo remains the same or not.

I believe I read one time that the cause of the lag was the fact that the servo channels are processed sequientially so if you set up dual elevators on 2 and 8 then it has to process five other channels before it gets to the second elevator servo. It this is true, you should be able to reduce the lag by using adjacent channels for the dual elevators but then you would have to use custom mixes and reassign some of the other controls. I have not played around with this to see if it works.

I've noticed a lag on the slaved elevator surface also. I use the older Futaba 8 channel radio but I bet it's pretty much the same as your 9 channel. the difference in travel speed is especially noticable when you've got 45 degree travel ie 3D. I read somewhere (from a futaba spokesperson or something) that this problem would not be noticable to most flyers so I'm not getting to bent out of shape about it. I just make sure the neutral and endpoints match.

peter

I'll have a go at moving the elevator channels to something like 7 and 8, rather than the 2 and 7 it is on at the moment and see if it does make a difference. If so then, it would indeed inidicate that the channels are processed sequentially in order and the wider the spacing, the more noticeable the difference.

Yeah I'm using about 45 degree movements for 3d, which is why I find it noticeable. Although the slower elevator probaly catches up within a fraction of a second, I find it very noticeable and I'm sure it must have some effect on the plane acting like an aileron to some extent.

I guess digital servos that allow speed programming would get around this problem as well, I think Hitec's are.

Using the Ailevator function is the most efficient way to program the elevator halves. I think you will have to kill the knobs that control channels 7 and 8 if you use a Pmix. Not sure but I think so. Why don't you just try flying it using the ailevator function and see how it flies first?


peter

Unfortuantely if I use the ailervator function, I can't use any other wing mixes and I like to have flaperons and spoilerons setup as well, so I normally just mix the elevator channel 2 with an aux channel like 7 or 8, which is effectlively what the ailervator function does anyway. However, perhaps the ailervator function recognises the fact that you want both elevator halfs to move at the same time and gets around the sequencing problem covered above. I haven't tried so can't confirm, anyone ?

OK, I'm having some deja vu here, I hope we are talking about the same things. I have a Futaba 8 channel radio. On a typical plane, with 2 aileron servos, two ele servos, two rudder servos:

I have the flaperon function turned on to tie the 2 aileron servos together. You can set up the flaps to drop with a switch, or see below.

I have the elevator halves tied together with the ailevator function.

I use the two 5 point mixes to set up flaperons and spoilerons (elevator to flap mixing).

I use a P mix to tie channel 4 to 7 for the two rudder servos, and another p mix to turn off the channel 7 knob.

if you dont have a progamming book (beyond the instruction manual) I'd recommend you buy one, I've found it to be very helpful.

peter