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can any radio do this ??

Old 01-14-2003, 07:20 PM
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Default can any radio do this ??

As we all know adjusting the rate of elevator travel of dual elevator servos when the servos are rotating in opposite directions ( one clockwise and one counterclockwise) is a real pain!! one servo seems to be slightly quicker in one direction and the other servo seems to be a little quicker in the opposite direction...this results in one elevator half traveling up a little faster while the other servo travels faster in the other direction I have had this happen with every servo combo i've tried (not digital). If we try to remedy this by slaving an extra channel it is possible to use a percentage in either direction to get the servos to be very close....however we all know what happens next !!!... elevator trim only works in one elevator half . on my radio I use the V tail mix to get this reverse slaving accomplished, however I can't adjust one servo as a percentage of the other with V tail!

So....the question,,,

are there any radios made that can adjust one servo against the other in percentage , in both directions, independently, in the V tail we can finally end this big problem!

ps....iv'e even tried reversing the rotation of the servo motor and this still won't solve the problem of synchronizing elevator halfs.
Old 01-14-2003, 08:57 PM
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Default can any radio do this ??

I do this all the time with my JR 8103.
No problems at all. I use a Mix that will allow both slave and master to be operated off the single trim.
P-Mix 5 or 6 for the 8103.

Left elev into elev channel
Right elev into aux 3
P-Mix 5 or 6 slave Aux 3 to elev
Then I set the ATV to aux 3 to ZERO for both sides of travel so the rotary knob does not move the right elev half.

Works very well.
Old 01-14-2003, 09:04 PM
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Default can any radio do this ??

Are you talking about the speed the elevator halves move at when you put in a single, fast stick movement, or the respective travel of the elevator halves.

If it's the speed of movement (elevators don't match while moving, but are correct when they have both arrived) then it's the servos, or binding in the linkage or hinges. You could use delay on the channels so the transmitter is the limiting factor in the speed, or use really hgh torque servos to overcome differential resistance.

If it's different end-points, then adjusting sub-trim and ATV (up and down) a bit on the two channels should help in the matching. This should work with V-tail, ailevator, or regular p-mixes.

ATV and sub-trim should operate on the actual servo channels, but dual-rate (or AFR in the 9Z) and normal trim operate on the function (elevator in this case).

Failing that, a curve mix with an almost straight line curve will let you match intermediate points as well as end points and center position.

Most radios will allow you to enable trim in the mixes so that the slave channel responds to trim inputs on the master channel.

I know for sure that the Futaba 8U, 9C, 9Z will allow you to do all of the the mixing above. The delay stuff is only on the 9Z.

I would expect the JR 8103 and 10X to be similar.

The entry level computer radios like 6X, 662 don't have these sorts of options available.

End-point matching can also be done with the JR Matchbox or Futaba MSA-10. These device will match end and center points, but won't match intermediate point.

Apart from that, I've heard of people taking a box of servos and finding matched pairs using a pointer attached to a horn, with a degree scale. Even the expensive digitals exhibit mismatches since it all depends on the linearity of the feedback potentiometer. Digital servos still use analog feedback, they don't have digital position sensors.

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