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Elevon Travel - Unequal.

Mode 1

Active member
#1
Hey All. Happy last day of 2018!

On my Mini Arrow I have unequal travel on my elevon. I get plenty of left but hardly any right. I did my best to make sure my control horn is over the seam. Electronics and servos are still pretty greek to me. Is there a fix for this? if it's a radio issue i'm flying frsky Qx7.

Any advice would be appreciated.



Sticks Centered
neutral.jpg




LEFT
left.jpg


RIGHT
right.jpg
 
Last edited:

SlingShot

Maneuvering With Purpose
#2
Hey All. Happy last day of 2018!

On my Mini Arrow I have unequal travel on my elevon. I get plenty of left but hardly any right. I did my best to make sure my control horn is over the seam. Electronics and servos are still pretty greek to me. Is there a fix for this? if it's a radio issue i'm flying frsky Qx7.

Any advice would be appreciated.



Sticks Centered
Did you center the servos before you made the pushrods? Did you start with a clean model on your TX? Or did you recycle an existing model?
 

SlingShot

Maneuvering With Purpose
#4
OK. That is a little weird. Where are the control surfaces with zero trim applied? If you used trim tabs to get them neutral, you should zero that and trim them with the sub trim to start. If you are using a lot of trim of any kind, you might be able to reposition the horn on the servo or another type of physical adjustment with the pushrod if you are able. Finally, and here's the fix, you can experiment by modifying the end points in the TX. This will allow it to move more.

Usually, this kind of problem occurs when you are using a lot of the servo's throw to zero the control surfaces. If that is the case, and you can't adjust it to your liking with the end point settings, you will probably need to fix your pushrods.
 

Hai-Lee

Old and Bold RC PILOT
#6
Firstly the angular position of both the servo output arm and the control horn to the hinge line are important. Both should be measured with the control surface in its neutral position, (with reflex deflection included).
The deflection is best measured in actual movement deflection amount as in +/- mm.

A few gotchas: A wing can fly quite well nose heavy and even be trimmed quite well BUT if nose heavy it can upset the roll handling especially at low rates or conservative control deflections. This can be due to differential drag issues.

A high power motor installation, with conservative control deflections, can have problems in turning in one direction due to motor/propeller effects. Easily checked for by cutting the throttle and rolling in each direction to see if roll response with motor off is equal.

Things to do!
1. Check and revise the balance point and hence the reflex angle of the wing.
2. Check if wing weight is not too excessive!
3. Increase the control surface deflections and also the amount of expo programmed in the transmitter.
4. Revise the angular positions of the servo output arms and the control horns for appropriate control surface deflection equality!

A photo of the entire servo/control horn angular deflections may help others to give alternative suggestions!

Have fun!