Pattern_is_Fun

Here's what I think I know: there is a pulse train that comes from the transmitter. Some "start" signal then the pulses start, at about 1.5ms per pulse, channels 1-X (10 in my case - JR10), and the position of each servo is +/- .5ms (approx) so the servos go from 1ms to 2ms (maybe .9ms to 2.1ms).. but the problem comes from running dual elevator servos - on channel 3 and 7 or X and Y, where the channels are not next to each other. If you use channel 3 and 7 as your elevator channels, you have approx 8ms before channel 7 get's it's input. You can see this delay in elevator travel. This was a problem I had 10 years ago, and it does not seem to be fixed yet. I'm looking for ways around this.

I am thinking that the servo 'speed' may help this, slowing down Channel 3 a bit. I'd like to syncronize as much as possible, but am not sure where to set the speed setting. There is another possability - use a multi-point mix and mix each point to track better, but not sure this will work.

Please comment on this as I'd really like to find a fix - else I continue to use 1 elevator servo to operate both elevator halves - but alignment is a huge issue on this - as many variables must be considered.

Thanks
Scott

flatspins1

I`ve just put 2 servo`s on the elevators of my new model and am having the same problem(PCM 9X).

I was wondering how to get round it also.

tail strike

My Feedback: (1)

I setup my elevater servoes with a HT programer on the bench so they are exactly the same, then I use a Y connecter to power them.

I am watching you

Larry S

Pattern_is_Fun

a "Y" harness will stop the problem, but then you don't have control over the endpoints. This issue here is different channels, and is there a way to overcome this.. Let's stay on track here.

sc

mglavin

My Feedback: (31)

More likely than not the problem is exasperated by model specific variables such as; linkage and physical orientation/location of control arms.

The software frame rate lag channel to channel is pale in comparison to the typical miss-matched and bashed control linkages.

The fix: accurately install and duplicate your control arms for all surfaces, they should be as close to perfect as plausible, this is not an easy accomplishment IMO... Then mechanically match your linkage to move the surface in equal travel volumes. The goal here is to realize equal servo angle or travel with equal surface travel arcs. This MUST be accomplished mechanically initially... The TX is utilized later in the setup process.

The easiest method to match surface travel volume is to utilize a 4� paper protractor fixed/centered on the servo together with a throw meter degree or angle finder. If one servo travels 50 degrees in each direction, they all should… Same is true of the surface; 50 degrees servo angle should net equal travel volume at each surface. 50 degrees servo angle will likely net around 35 degrees surface deflection at the surface (linkage ratio dependent). Each servo/linkage/control arm must output equal numbers mechanically. This accomplished by correctly locating the control arm, finding the center of the surfaces travel arc and matching the servo center/neutral to same. Variables that help are sub-trim, pushrod length and control arm heights once the control arms are fixed in-place permanently.

Any time you introduce an offset weather it be at neutral or end-point you skew the requirement for linear and or scalar travel. Uneven end-point values required to match surface travel point to mechanical miss-matches in nearly all cases. These unequal values cause and effect to some degree disproportionate surface travel values.

Pattern_is_Fun

I have heard the new JR radio, not yet released, will have elevator channels next to each other - to prevent this problem. This may be accomplished by having all channels 'assigned' to any channel you want, so you could put channel 1 and channel 2 as elevator - just as a 'for instance'. What this tells me, and Futaba solved this problem with their newer 14MZ and 12MZ, is that there IS an issue, no matter how your linkages are set up - and not many, if any, have solved it. I know excellent JR Team pilots that fly with dual elevators, and it does not seem to affect they way they fly, but it just bugs me that the elevators do travel at different 'times'. I also know other JR Team pilots that will not use dual elevators for the above reason. Perhaps some are mixing differently - which is why I wanted JR to reply to this - maybe they know something we don't??

sc

tail strike

My Feedback: (1)

I am trying to keep you on track, with the HT programmer you set the endpoints and center on each servo to match on the bench.
Then when installed if you get the linkage exactly the same the travel will have the same speed and the end points will be the same. Very simple to get it right.

I am watching you
Larry S

mglavin

My Feedback: (31)

My apologies for mixing it up in the JR factory Support Forum, I did not note where the post originated.... I’m sure JR’s Danny will offer his thoughts ASAP.

That said the frame rate problem is MINIMAL and NOT the root of the problem... I seriously doubt any will recognize a several milli-second delay if all else is spot on; in fact it’s simply not an issue IMO. Look real hard at your mechanical set-up and you'll be amazed of the disparaging difference of one elevator halve to the latter. Proper set-up techniques are the key to match surface travel arcs, its time well spent when it all said and done.

Futaba’s 14MZ like MPX assigns channels directly to the source, i.e., all 14 channels could source the same stick and or switch input if desired no mixing required... Not sure about the 12MZ though?

You can utilize a Matchbox to drive several servos, this device sources signal from one channel and allows you to individually set neutral and end-points. However if your linkage setup is not matched you'll have to use variable settings to work around the miss-matched mechanical travel arcs same as before. Minimizing overall available pulse-width to work out set-up short comings comes at the cost of system resolution.

It occurred to me that one could evaluate the benefits of matching the linkage system by simply installing a Matchbox with all settings/values equal and observe the surfaces.

Pattern_is_Fun

If I was the only one seeing this, I'd agree, perhaps, that my set-up is not ideal. But many top flyers have seen this - not just me. I have heard of the HT setup, and would agree you can do many good things with the box - but does not work, as you point out, on JR. The frame rate is the issue - but there are a few things I don't know. 1) How the mix works with the frame rate - if I mix ch3 and ch7, how does the mix effect the frame rate? 2) if I use a multi-point mix, and mix the two channels, will this help anything?

sc

dsnyder

I can only echo Michael's posts, the information he provided is right on the mark. I have never had a problem with channel update rate, mismatched elevators using the dual elevator function is far more commonly attibuted to mechanical errors and problems. If you have these problems, it is best to fix them than to concern yourself with the update rate. I use the dual elevator function etc in all of my models with dual elevators and it works great. The update rate in general is much faster than the human eye can see.

Pattern_is_Fun

Thanks Danny, good info !

sc