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Dual elevator servos and 6 channel transmitter ... ?

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Old 03-13-2008, 04:15 PM
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Ernie Misner
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Default Dual elevator servos and 6 channel transmitter ... ?

Greetings, with my T6XA transmitter I am limited on how to run dual elevator servos. I know I can use a reversing Y cord as one option, get a reversed servo, or try to turn the arm around on one servo..... but would rather not do any of these unless necessary.

I've heard it is not recommended to use channel 2 as the master (left elevator half) and, say, channel 5 as the slave (right elevator half). This would eliminate the trim function for the right elevator half, right? Why couldn't I just set the neutral point on the right elevator half using the linkage adjustment? If the linkage geometry wasn't identical for the two halves, then the travel limits might be different and there would be no ATV adjustment for the right half.... ?

Thanks for any input!

Ernie
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Old 03-13-2008, 04:18 PM
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jmohn
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

Otherwise, you could just use hardware to make a linkage that operates both surfaces from one servo.


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Old 03-13-2008, 04:49 PM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

http://www.futaba-rc.com/radioaccys/futm4155.html or http://www.futaba-rc.com/radioaccys/futm4150.html may help. Read the manuals and decide.
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Old 03-13-2008, 05:57 PM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

I have the same radio and it has the dual servo for elevators limitation-try to mount servos so you don't have that problem or use one Hi-tec and one Futaba servo-Hi-tecs are opposite rotation to Futaba.
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Old 03-13-2008, 10:39 PM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

Try this..Mix Elevator with Gear Channel...go to Travel Adjustment or End points...adjust the Gear to "0"....reverse either the elevator or gear channel...
with the MIX Elevator Primary and the Gear as the SLAVE...should work...I Do not know whether there is a Mix Program on your TX..[8D]

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Old 03-13-2008, 10:55 PM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

REGARDLESS of Geometry and linkages. You will have a latency(slower) issue with slaved servo. If you reverse a servo and use programmer to set centers and end points, then run a y you will have simultaneus servo travel no BS. There are several that have supported this. This is the only way I can get 9cs to have exact travels within .010 of each other thru the full range. This is using 5955 hitecs if you are using a less servo your centering issues may never be resolved. HFP 20 programmer is worth its weight in gold.

3DAP
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Old 03-14-2008, 07:01 AM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

Buckle down & purchase the SR10 reverser from Futaba & have it done with. I have one on my U-Can-Do 60 & it works great. Did I mention it's basically plug & play? A few less Starbucks & a couple of cold ones & it will be paid for!
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Old 03-14-2008, 03:03 PM
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Ernie Misner
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

Thanks guys for all the great support!

3DAP, doesn't your 9C transmitter have an Ailevator function that is designed to run dual servos? The old 8C has that function.

I wasn't aware that a slaved channel ran slower than the master. Interesting!

Thanks loads guys ..... oh the Futaba reverser is 35 bucks and it weighs nearly an ounce. Not a big deal on larger planes I guess.

Ernie
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Old 03-14-2008, 03:15 PM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

ORIGINAL: Ernie Misner


I wasn't aware that a slaved channel ran slower than the master. Interesting!
Unless of course, you have a DX-7
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Old 03-15-2008, 12:36 AM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

Yes any channel slaved on the ailevator will have latency. Enough to see it. This is why digital servo reversing one servo and using a y makes it perfect and crisp. I got my 9cs in midst of spread spektrum technology. I do not have freq conflict and require more than seven channels so I wont go spread until it has got all bugs out.
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Old 03-15-2008, 07:06 AM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

Futaba's website specifically mentions the lag-time (latency?) when using two channels to drive two elevator halves. This is on the 9C website, don't know about the 6-channel Tx's.

Reversing one servo with the programmer, using a straight (non-reversing) "Y" from one channel , and fine tuning endpoints with the programmer has worked perfectly for me. My experience with doing this is, however, limited to setting up two airplanes.

The programmer takes a bit or practice to become proficient in its use.

N.B.: Apparently Hitec is about to release an entire new series of servos and and a new programmer for use with those servos. Also, according to something posted here in RCU, the new programmer will be backward compatible with the older servos, but the older programmer will not be forward compatible with servos in the new series.
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Old 03-15-2008, 09:28 AM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?


ORIGINAL: rlmcnii


N.B.: Apparently Hitec is about to release an entire new series of servos and and a new programmer for use with those servos. Also, according to something posted here in RCU, the new programmer will be backward compatible with the older servos, but the older programmer will not be forward compatible with servos in the new series.
The new HFP-20 programmers have been out for several months now, but it seems the new servos have been backed up a bit from the originally announced 1st quarter '08 release date.

The new servos have overload protection and a 2048 resolution which can be programmed with the new programmer. It's my understanding that while the new programmer is fully backward compatible, the older HFP-10 programmer will work with the new servos but cannot access the resolution and overload protection features of the new servos. Hard to confirm that as the new servos aren't here and IIRC Mike Mayberry over on the Hitec support forum has indicated this is the case but don't take that as gospel...

Since the HFP-10 is not upgradeable, I just went ahead and got the new HFP-20 since I think the new features are well worthwhile and even if the HFP-10 will do most of the programming, it won't handle the new features.

In any event, that's the reason you see all the vendors cutting some great deals on the current crop of servos which will be replaced by the new higher resolution models.
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Old 03-15-2008, 10:41 AM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

Zeeb,

Thanks for the clarification. I had not been reading the Hitec Support Forum and had missed some information that was already out there. I was aware of the existence of the new programmer, but not of the new servos until everyone put the present series on sale.

Hope the new servos work out well.
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Old 03-16-2008, 01:58 AM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

There is an option to mix two channels on your 6xa. You have to dedicate the switch for dual elevator rates though. Basically when it is set up dual elev work with high rate switch on. And when its is set to low rate only 1 elev works. I did this for a while on my sons 6xa but found that programming a servo is much easier and more accurate. Also we like to fly with low and high rates. The set up is in the manual
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Old 03-17-2008, 02:59 AM
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Ernie Misner
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

I went flying today and my buddy showed up with his new Frenzy and Saito 125 combo. With his 9C, he slaved channel 5 with 2 as the master to run his dual elevators. If there was latency on the channel 5 half I couldn't see it when we were setting up and adjusting it. It flew great. What am I missing here? .... well have to admit we weren't solely looking for a tiny difference in the speed of the two halfs though.

Thanks loads guys and thanks for all the great replies and options. I really appreciate it.

Ernie
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Old 03-17-2008, 04:24 PM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

Hi Ernie,
I use the same setup on my CG Extra 300 (old BIY kit) with a 9C super, originally I used the dual elevator mix to ch 8, there you could detect a little lag on the second half of the elevator, it never seemed to be an issue when flying, my buddies who are much better 3D and pattern flyer's found no evidence of it affecting the handling of the plane, so with the slave on channel 5 there is less lag in the second elevator servo. The other benefit of using the P-mix to channel 5 is that you no longer need an 8 channel receiver, no small consideration if you are thinking of going 2.4Ghz[8D]
Cheers,
Pete
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Old 03-18-2008, 03:13 PM
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Ernie Misner
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

Pete, that is good information. VERY interesting that there'd be less lag with the 2>5 setup. Good ol' Gear channel. Go figure....

So, with my 6TA transmitter, if I slave channel 2 to 5, for the dual elevators what would I possibly be lacking that you are doing with your 9C? Yes, the 6TA does have 2 programmable mixes.

Thanks loads,

Ernie
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Old 03-18-2008, 03:29 PM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

Hi Ernie,
I think the issue with doing that mix on the 6AT is that I don't believe you have the option of making the trim on the master channel couple to the slave channel, the 9C does have that option in the P-mixes. Without the trim being coupled, only one half of the elevator would respond to trim inputs at the transmitter.
Why it would result in less lag, as I understand it, the channels are processed sequentially, so the closer together they are in the sequence to less lag, channel to to 8 is a large delay, 2 to 5 would be less. The high end radios that provide servo sync, do it by grouping the two channels being used for dual elevators or ailerons on adjacent channels, resulting in closer matching of the movements of the two servos.
Pete
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Old 03-18-2008, 04:12 PM
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Ernie Misner
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

Hey Pete, you are a wealth of knowledge.

Okay, so on my 6A tx, I would be lacking some trim adjustment for the elevator half on channel 5. Couldn't I just spend a little extra time setting that half up by adjusting the trim with the linkage? Oh...... I see, you don't mean subtrim or ATV, you mean I couldn't adjust the trim while flying except on the channel 2 half. That would be a bit limiting. Still, if not too picky couldn't I adjust the final flight trim on channel 5 with the linkage between flights until I was happy with it and then just leave it that way?

Thanks loads,

Ernie
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Old 03-18-2008, 05:24 PM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?


ORIGINAL: Ernie Misner
Hey Pete, you are a wealth of knowledge.
Ernie
I wouldn't go that far, but thank you[8D]

Y'know you probably can get away without the trim on the slave. as long as you don't have to dial in too much. Once you get the plane flying hands free, adjusting the slave surface to match the position of the master may be fine. That said, I don't think that this would be a good idea if you were going to do a giant scale aerobatic ship for IMAC competition, but a sport model will probably be fine. Consider the typical sport model with elevator halves joined by a torque rod wire joiner, does the half driven by the torque rod match the other half under flight loads?
Maybe someone else will chime in on the trim issue.
Pete
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Old 03-18-2008, 11:54 PM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?


"Futaba Faq.
With most transmitters, when you use separate control channels to operate a dual-surface control, such as elevator, the two channels are not processed at quite the same time in the transmitter. On most Futaba transmitters, aileron is channel 1. The second aileron servo would be on channel 6 or 7, depending upon the configuration. Because channel 7 is processed after channels 1-6, a slight delay will be noticed on the control surface if you move the stick rapidly from one end to the other. This is especially noticed if your model has large control surfaces. For exact synchronization, a 'Y' harness with a reverser on one leg would be needed.
In practice, though, this slight difference in the movement of the two surfaces hasn't caused any problems in model flight, and can be ignored.

The new Futaba 14MZ reduces this as much as possible with its different grouping of control functions, so that if you have multiple channels on the same function, they are processed closely together."

BAX
Futaba Moderator


I choose to have them exact, especially on large control surfaces at high rates. I have set them up 7, 8, and 5. The Only exact set up is Spektrum or Y reverse programming. Sport flying may be fine. But look a little closer if your snapping out of loops or wing rocking when your not suppose to be. Channel five shows this as well.

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Old 03-18-2008, 11:58 PM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

Where did you find flying weather in Tacoma Wa on Monday??? It rained like Hell out here in Grays harbor. Come on Spring time.
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Old 03-19-2008, 03:16 PM
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Ernie Misner
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

Hey 3DAP, what do you have set up on channels 3, 8, and 5 exactly? It was sunday when I made it flying, and it was kind of gray and windy but the rain managed to hold off long enough. Come up to our field sometime? Or vise versa.....

Pete, when using a mix (to drive an elevator half or whatever) have you ever seen someone cause a crash by inadvertantly hitting the switch that turns that mix on? Seems like that would be one advantage of using the built in Ailevator function to program the 2 halves, that there is no switch to keep in place.

Thanks, and thanks to Baxter too,

Ernie
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Old 03-19-2008, 11:06 PM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

Ernie,
I have slaved the elev chan (2) to gear 5 and to aux channels 7 and 8 and have come up with a small amount of lag. Being a machinist I have a tendency to see small amounts of
movement. Unfortunately I can see lag on all three channels. I spent a lot of time trying to dial in movement without knowing about lag. This is on a 9cs with Ailevator function. I did fly these set ups and only noticed a small amount of change, But on the ground I could see it a lot more. And it drove me crazy enough to buy the 5955's and new Hitec servo programmer. I am much happier when set up with a y and a reversed servo. I also had a few other experts support on this issue. I can not go spread spektrum yet so I have found the best repeating set up IMO. I have talked to other hardcore 3drs who have done the same or have 2.4.

As far as the mix on the 6X I have one and had it set up with dual elevator funtion. There is a chance of hitting daul rate elev switch and only driving 1 side. My son did it. But it was just a crazy right aileron input, and was able to see what happened and correct before I sh$t my pants. since then we opted to have dual rates work as they are supposed to.
I am constantly changing rates so I hated it. We went with programmable servo's and they are way better for us. If you can keep your thumbs off the switch it would be fine.

The weather out here has sucked big time, I may have to drive to Tacoma to find decent weather. I will PM you and talk clubs.
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Old 03-20-2008, 06:55 AM
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Default RE: Dual elevator servos and 6 channel transmitter ... ?

Ernie,

This is what I use to do a few years ago when I had on a 6 channel radio. When I bought my servos for a new plane I had just bought I'd have one of the servos reversed internally to use on the elevator. I always got my servos from Servo City and for an anolog servos it was $8.00 and free for digitals. then just use a standard "Y" harness.
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