Lagging Servo?

[Fade2Black]

Hey Guys.. Just noticed this, and I thought I would throw is out there.

28% Extra 300 (not that it matters)
6v 4700mah nimh battery
JR 921 receiver
JR x9303 Radio
Hitec 5945 on the elevator halves.

In flight mode one and two the elevators are spot on:

Problem is If i give full up elevator in full rates, and then emmediatly full down elevator, the right side elevator half lags behind. Its noticable visually which is why I am concerned. This happens when the battery has a full charge or done for the day. doesnt matter the voltage. I inspected the servo wire and extentions, and there is no pulls or frays. The connectors are okay as well..

Has anyone seen this?

I may want to add that my buddy came over and programmed the servo's with his hitec programmer, so possibly he may have slowed down the servo a bit, but that would be visual on any rate that I have set.

I am going to swap the channel input on the receiver too see if the lag moves to the other elevator while at the field today. I am VERY RARELY in full rates other than a elevator or flat spin, and the plane will hover in the second flight mode, but I am concerned.

Any info would be appreciated.

[Edge 540]

The following is what I've been told:
The radio system refreshes the servo positions in sequence. Not positive about JR but I heard futaba used to do all odds then all even channels?
Example
(1-3-5-7-9-2-4-6-8) (1-3-5-7-9-2-4-6-8) (1-3-5-7-9-2-4-6-8)

So if you had for example one servo on 1 and the other on 6 you've got a good bit of lag between those. Having one or both reversed can make the situation worse. Keep in mind this was most noticed in the 9c etc which already had 140ms of latency. The elevator matching was ugly sometimes.

Both manufacturers now have servo grouping which I believe assigns similar servos to adjacent positions in the refresh sequence so Ailerons will be 1-2-3-4 etc. They might even update simultaneously not positive. Ideally the problem should be all fixed now, or at least as much as the radio manufacturers can do.
Having said all that I did not notice any problems setting up my Extra. I use a 9303 and 7955's and I took a LOT of time to make sure it was right. Hours of matching deflections and I did not find any lagging.

Things I'd suggest trying:
-try a different power system on the bench and see if you can remove the issue. Those cells may not be putting out as much power as you think
-check your extensions. Are they heavy gauge? What about those connectors?
-if you plug two servos directly into the receiver with no extensions or linkages is it still lagging?

[Fade2Black]

	Quote: Originally Posted by Edge 540
	The following is what I've been told: The radio system refreshes the servo positions in sequence. Not positive about JR but I heard futaba used to do all odds then all even channels? Example (1-3-5-7-9-2-4-6-8) (1-3-5-7-9-2-4-6-8) (1-3-5-7-9-2-4-6-8) So if you had for example one servo on 1 and the other on 6 you've got a good bit of lag between those. Having one or both reversed can make the situation worse. Keep in mind this was most noticed in the 9c etc which already had 140ms of latency. The elevator matching was ugly sometimes. Both manufacturers now have servo grouping which I believe assigns similar servos to adjacent positions in the refresh sequence so Ailerons will be 1-2-3-4 etc. They might even update simultaneously not positive. Ideally the problem should be all fixed now, or at least as much as the radio manufacturers can do. Having said all that I did not notice any problems setting up my Extra. I use a 9303 and 7955's and I took a LOT of time to make sure it was right. Hours of matching deflections and I did not find any lagging. Things I'd suggest trying: -try a different power system on the bench and see if you can remove the issue. Those cells may not be putting out as much power as you think -check your extensions. Are they heavy gauge? What about those connectors? -if you plug two servos directly into the receiver with no extensions or linkages is it still lagging?

Thanks for the information. The Latency I am unsure of other than the Visual i get from the elvator halve. I will check through the extentions again to make sure all is well. but on a bench with no control surface, I am unsure if I will be able to see it as the elevator half is much larger than a control horn.

I havent tried putting two servos directly into the receiver with no extentions. I will bring an extra servo with me today. My first test is going to be swapping the servos to versa as appose to visa if you know what I mean. If the half that is lagging right now is still lagging then I know that is is either the servo, the wire or the receiver. If it is the other one, then I know it is receiver based. I will then test the voltage and amperage on the channel and see if they are significantly diffrent from the other half

The battery was brand new sitting in the bag. I purchased the plane second hand, and he had a dual setup with a batshare on 6v nimh. I dont like using other peoples batterys and I didnt have two packs of matching mah to put on it. I took the dual setup out for the time being. I know nimh can have voltage drops issues due to exessive amerage draws, but jsut the elevator half and not the other surfaces?

Ill keep ya posted!

Thanks again!

[A-Track]

	Quote: Originally Posted by Edge 540
	The following is what I've been told: The radio system refreshes the servo positions in sequence. Not positive about JR but I heard futaba used to do all odds then all even channels? Example (1-3-5-7-9-2-4-6-8) (1-3-5-7-9-2-4-6-8) (1-3-5-7-9-2-4-6-8) So if you had for example one servo on 1 and the other on 6 you've got a good bit of lag between those. Having one or both reversed can make the situation worse. Keep in mind this was most noticed in the 9c etc which already had 140ms of latency. The elevator matching was ugly sometimes.

I'm going to have to look at what channels I have my elevator plugged into as I fight the same problem

[Edge 540]

My IMAC Extra setup (in Avatar) is pretty much stock-basic-no frills. 9303 - AR9000 - two remotes. My linkages are exactly identical in length. Two regulated fromeco 2700's through separate switches to the RX. Deflections were set up using a digital deflection gauge. There is no visual discrepancy between my elevators and no tracking issues in flight.

I think checking the amp draw is an excellent idea. I did that when setting up my ailerons. Your hinges might have slightly more drag on one side than the other. The nice thing about c-arf pocketed hinges is they have essentially NO friction. Back to the battery... I personally would never fly a 50cc on one battery and especially not one nimh pack. They have a poor track record with me. I recently lost my 8' telemaster camera plane because the 1800 nimh 5 cell pack couldn't provide the power.


Checked before the flight under load and it was FINE. Nimh cells are funny sometimes. They will false peak if you charge them too fast, they tend to have high internal resistance etc etc. I'd really really consider the power system to be suspect. Just cause the battery is in the packaged doesn't mean it wasn't over 2-4 years old from the point of manufacture.

[3D-Seth]

How much of a lag is there? Does it do it both directions (up and down, or just down)? And are you sure its lag, or are they just in different places in the middle of your travel? Try moving the stick to 3/4 deflection, and see if the halves stay apart, or if the laggy one eventually matches up to the other one. Definitely try swapping channels and see if it moves or not. If it doesn't move, I would suspect your power system to be the problem.

Seth