Trim setting changes when going to high rates
 

I'm flying my WH 28% Extra with a Futaba 8UAFS/R148 receiver, and Hitec 5945's all around but on throttle. When I got from low to high rate on the elevators, the plane responds like I added 2 or 3 beeps of down trim. Go back to low and it's perfect again. Ailerons and rudder are just fine. Any ideas why????

RE: Trim setting changes when going to high rates
 

The problem is that your pots on the sticks have come a little bit out of calibration. I had that happen on my 8U, and I fixed it myself, but the adjustment is VERY sensitive. Your best bet would be to send it to someone that is qualified to check if the pot is worn, or just out of adjustment.

HTH
Jim

RE: Trim setting changes when going to high rates
 

I've got a 2nd 8UAFS transmitter that's like new. I fly with one, and have a back up that I use when installing radio gear etc. I'll check and see if it does it with that tranny also. You can actually see the elevators move when sitting on the ground and flipping the dual rate switch. If the new one works ok, it's time to send it in......

Not like I haven't used it a lot. My detents in the thottle stick are all worn off. :D

RE: Trim setting changes when going to high rates
 

I had that happen to me with my new 9C..couldnt figure it out so I erased the model memory and started over and it went away! With my WH Edge I programmed everything and it didnt do it so in my case I musta had something programmed in wrong..

RE: Trim setting changes when going to high rates
 

I can't remember of the 8U specifically but are the D/R and the End Point percentages equal values at extremes? For instance can you set 120% high D/R and 120% End-point or is the D/R MAX a lower total percentage of the two?

RE: Trim setting changes when going to high rates
 

I'll have to double check, but I think if your end points are like 120%, then anything past 100% on the D/R switch doesn't do anything. I still wouldn't think this would change the trim setting though.............

RE: Trim setting changes when going to high rates
 

You ay not have your trim perfect.
Remember that it is still a percent of max deflection.
I would recommend to change your trim steps from 4 to 1 and trim the plane on high rates.
It should fly well on low rates after this is done.

RE: Trim setting changes when going to high rates
 

If Dual rate can drive the surface farther than the ATV setting for this surface you got problems. Trim changes could be realized as the over travel of the specific surface is different of each mode. Make sure ATV and D/R are at least equal. If you need more travel turn up the ATV and adjust the low rate and high rates accordingly.

RE: Trim setting changes when going to high rates
 

I'll double check my settings, and I've already got the trim setting down low. Very little movement for each beep.......... I'll try all these and trim on high rate also, and then see what it does on low.

Unfortunately I'm tied up for the next several days and won't get fly. [:@]

RE: Trim setting changes when going to high rates
 

Best way to tell if it is a slipped pot, is to set the trim a neutral. Then reverse the channnel while all is turned on. If the servo moves when reversed at neutral, your pot has slipped in the transmitter.
I had this problem with a Hitec about ten years ago. The service tech talked me thru the repair(adjustment) on the phone as I need the radio the next day for a fly-in.

RE: Trim setting changes when going to high rates
 

Well I managed to find a few extra minutes today(not really, just put off working for 45 minutes, but you guys have never done that have you. ;)) and I copied my transmitter program over to my other like new 8UAFS. Guess what, no more trim change when going from low to high rate on the elevator. Must be a bad pot.... Icebird nailed that one.:D I'll just pack it up and send it off. I've flown it a good 100 hrs/year for the last 4 years, so it wouldn't hurt to be gone through real good....

mglavin,

I did some checking on my ATV'S and D/R percentages. I can go to 140% on each of them. I normally set my D/R for high on 100%. I did a test with a 5945 plugged in a receiver on channel 4 and this is what I came up with. If the atv's are set at say 120%, and the d/r is at 100%, servo arm moves say 45 degrees. I can bump the d/r up to 140%, and it changes the end point to 60 degrees. If the atv's are at 140% to begin with, 100% d/r is like 50 degrees, and 120% d/r will get you maxed out at 60 degrees. I can continue to move the d/r to 140%, but it does nothing after 120%. These tests were done with no subtrim or trim added in the transmitter. It was funny that with atv's at 140%, I could go to 120% d/r on left rudder to max out throw, but the right rudder was maxed out at 110% for the same 60 degrees throw.

I always like to set my servos up for maximum resolution, so I wonder if I should be using 110% on d/r for setting up my throws, or leave the d/r at 100%, and my atv's at 110%-130%, that way I wouldn't have to worry about *****g out the servo?

RE: Trim setting changes when going to high rates
 

I don't understand how the pot could be a problem realized of flipping the dual rate switch?

Dual rate is percentage of the MAX ATV setting.

The offset realized in rudder throw is likely caused by the TX's pulse output at neutral, its typical to see the anything but 1500us at neutral and then most servos less Hitec programmables center somewhere other than 1500us too.

Mechanically setup your model to move the desired travel arc's first with 130% MAX ATV. Then use D/R hi/lo to adjust the individual surface to your liking for best results.

RE: Trim setting changes when going to high rates
 

I don't either, but both transmitters are programmed exactly the same, and it doesn't do it on the newer one.......

Why don't they just use 100% then as max for d/r??? 140% atv + 100% d/r = max servo travel...........no brainer that way.
:D

RE: Trim setting changes when going to high rates
 

The pot is the source of the signal whether you're on high or low rates so that's a wash. It seems more like a tx glitch than a worn pot. Almost as if your high rates is treating the trim as an input signal from the stick and amplifying it, hence the movement.

RE: Trim setting changes when going to high rates
 

I ran one more simple test this morning just to make sure it is the tranny. I went to an open model memory slot, hit the reset data function to wipe every thing clean. Plugged a 5945 into the #2 spot on the receiver, and set my dual rates at 100% and 30%. Servo still moved 1/16" or so. Did this also with my like new transmitter and it didn't move at all. Next I tried what TLH101 said about reversing the servo with the trim in neutral. Sure enough on the suspect transmitter the arm moved just like it did when flipping the high/low rate switch. Rock solid on the new transmitter.

Thanks for all the help guys. I think I'll be checking all my channels periodically from now on for a bad pot.

RE: Trim setting changes when going to high rates
 

The pot is probably not bad, it has just moved in relation to the stick. The sticks rotate the pot and if it is set at a differant point on the stick, the trim change is a result. There a couple of screws that clamp the gimbal to the pot. you can loosen the screws, and adjust the pot until there is no change when you reverse the channel.

RE: Trim setting changes when going to high rates
 

I'm just going to pack it up and send it to Futaba. I've got 4 or 5 years of flying out of it, so it may just be a good idea to send it in and let them do a good tune up on it. :)

On a final note. I got to fly my 28% WH Extra this evening with my good 8UAFS transmitter. WOW! What a difference it makes. I didn't realize how much I was fighting the plane when I was on high rate elevator, especially when in a TR, and when flying out of a TR. I always switched back to low rate when coming out of a TR because I wasn't comfortable on high. Now it's no problem. :):)

RE: Trim setting changes when going to high rates
 

My 9VAP has just started to do this changing trim when D/R switch moved....but its now 17years old, so I havent done too badly. Will check with tests noted above and get it serviced. Am I right in thinking new pots will a) fix the problem and b) reset all flight settings?
tks,
jp

RE: Trim setting changes when going to high rates
 

I'm assuming so, I still haven't sent mine in.:D