Geometry and Elevator throw error

[tailskid]

Not the first time I've used two elevator servos but this has me baffled.....Both servos (Hitec 5585MG) have been 'reprogrammed' to factory defaults.....both arms are vertical and both elevator connections are in the same location...

In neutral, both halves line up perfectly, but when I add (say) up elevator one elevator moves slightly more than the other, but both end up equal at full up!

I did notice the elevator half that moves 'too much' isn't perfectly level with the horizontal (down about 1/32) whereas the other side if perfectly flush.

Haven't flown this one yet....It is a Fly Models 30cc Sbach 300 powered by a DLE30 - any suggestions?

What I have tried:

Moved the pushrod "up" one hole (same problem, but on the other side)

Moved the servo arm 'back' toward the tail one notch - not a whole lot of difference.

I do have access to a Hitec Programmer, so I guess I could do something with that - if I knew what to do

Thanks for reading,

Jerry

 

[stangflyer]

tailskid said
Not the first time I've used two elevator servos but this has me baffled.....Both servos (Hitec 5585MG) have been 'reprogrammed' to factory defaults.....both arms are vertical and both elevator connections are in the same location...

In neutral, both halves line up perfectly, but when I add (say) up elevator one elevator moves slightly more than the other, but both end up equal at full up!

I did notice the elevator half that moves 'too much' isn't perfectly level with the horizontal (down about 1/32) whereas the other side if perfectly flush.

Haven't flown this one yet....It is a Fly Models 30cc Sbach 300 powered by a DLE30 - any suggestions?

What I have tried:

Moved the pushrod "up" one hole (same problem, but on the other side)

Moved the servo arm 'back' toward the tail one notch - not a whole lot of difference.

I do have access to a Hitec Programmer, so I guess I could do something with that - if I knew what to do

Thanks for reading,

Jerry

Hey Jerry.... I've seen this before. Not from just a Hitec, but others as well. I am curious if that 1/32" of an inch difference, (although not much) may be causing the "throw" to change exponentially as travel of the elevator is increased, yet coming to full deflection as with the other. I can't see it being enough that it would cause your symptom as you describe. Have you swapped out your elevator servos from left to right and vice versa? If so, does it still do the same thing? If it still remains, then I would probably see if you can program it out. Another thought would be, if you are splitting the servo halves, left from right, you should be able to dial that in with your radio. If however the symptom follows the servo, then perhaps you have a servo that is not properly recognizing input through the circut board. Deciding which one though could be a chore. I would like to hear what you come up with.

 

[ericb]

tailskid said

Not the first time I've used two elevator servos but this has me baffled.....Both servos (Hitec 5585MG) have been 'reprogrammed' to factory defaults.....both arms are vertical and both elevator connections are in the same location...

In neutral, both halves line up perfectly, but when I add (say) up elevator one elevator moves slightly more than the other, but both end up equal at full up!

I did notice the elevator half that moves 'too much' isn't perfectly level with the horizontal (down about 1/32) whereas the other side if perfectly flush.

Haven't flown this one yet....It is a Fly Models 30cc Sbach 300 powered by a DLE30 - any suggestions?

What I have tried:

Moved the pushrod "up" one hole (same problem, but on the other side)

Moved the servo arm 'back' toward the tail one notch - not a whole lot of difference.

I do have access to a Hitec Programmer, so I guess I could do something with that - if I knew what to do

Thanks for reading,

Jerry

What radio are you using?

 

[tailskid]

Radio is JR 9303 and I'm using a matchbox for the two servos and yes, I tried swapping the two elevator servos and nothing changed

 

It should be interesting tomorrow when I test fly her and see what happens when I gently keep adding elevator

 

Thanks stangflyer for the suggestions and I'll keep working on it (perhaps I could slow down one of the servos??? I know you can with the flaps, but don't know about the elevator).

 

Jerry

 

[stangflyer]

tailskid said
Radio is JR 9303 and I'm using a matchbox for the two servos and yes, I tried swapping the two elevator servos and nothing changed

 

It should be interesting tomorrow when I test fly her and see what happens when I gently keep adding elevator

 

Thanks stangflyer for the suggestions and I'll keep working on it (perhaps I could slow down one of the servos??? I know you can with the flaps, but don't know about the elevator).

 

Jerry

You're welcome. I like to do process of elimination. So you've swapped the servos and the condition still exists. Rule out the servo. That leaves the programming in the radio or the actual geometry itself. Oh, are you running separate channels for each elevator servo? Or ("Y'd") into one channel. I prefer the split channels. Haven't used the a "Y" harness in forever. Just curious.... would really like to help if I can. I solved an identical issue with one of my airframes two years ago. Once the elevators were split to different channels, I changed the parameters in my radio.

 

[tailskid]

Stangflyer I have tried both servos into separate ports and now I have them running into a JR Matchbox - either way same problem

 

It has to be geometry. I took some pics to show how the left elevator isn't flush like the right one is....I may have done that because I redrilled the stab/elevator in order to use a larger hinge (Robarts).

 

 

 

[stangflyer]

Ah yeah.... I see the difference. What is weird though is that if the geometry is off just enough through the initial travel to cause one elevator to be slightly higher at first, but final throw is the same as the other. Curious of what it is going to be like in some maneuvers. I really don't think you have much to worry about. Maybe just not as precise at some points as it is at others. Good luck with the test flight....

 

[tailskid]

 

She 'almost' balances on the recommended location (4 7/8" - mine is at 5") but dry....I'm going to be charging my batteries overnight and hopefully a successful series of test flights! Thanks for the vote of confidence

 

[quadracer]

If one half isn't flush, then your linkage geometry is off slightly. Try subtrimming that channel to even it up, and adjust your endpoint on the other side to match it.

 

[tailskid]

I will have to try that at the field and see what happens.....thanks for the suggestion.

Jerry