FlyerBry

My Feedback: (8)

Hi all, I have a Futaba T6XAS transmitter and I am setting up the radio to work with a Great Planes Piper Cub that I bought second hand. My question revolves around the throttle and the reversing features. To have the throttle servo work properly with the servo installation in the plane I had to reverse the throttle channel (#3) so it would be moving in the proper direction. While tuning the engine in my garage I realized that the engine accelerates more in the first half of the throttle stick travel than in the second half of the travel which is the reverse of what it should be. It should be giving the more delicate control around idle and not wide open.

Later that evening I checked my manual and noticed the mention of the TREV menu option which allows you to reverse the throttle stick. Figuring this is what I needed I changed the setting on the TREV menu so the throttle would be reversed. Tonight I went out to tune the engine some more after installing a new plug in the engine. Upon starting, the engine immediately went to full throttle when I had the throttle stick set at only a couple clicks from bottom. I immediately figured that I had the setup reversed and verified this by moving the throttle stick all the way to the top and the engine started to idle.

I remembered that I had originally reversed the servo throw on the REV menu before reversing the stick setting on the TREV menu so I figured I needed to go back to the REV menu and set the throttle channel back to its normal throw direction. I did this, but found the throttle stick still worked in the opposite way with full throttle being all the way down and idle being all the way up. It seems as if reversing the throttle in the TREV menu reversed both the direction of the throttle servo and where the fine control in the stick lands.
I can fly it this way (with the throttle set to go in the correct direction as I originally had it) but would like to get it working properly so the engine isn't running at close to full speed at half throttle.

Anyone dealt with this before? [&:]

Longaly

I have the same radio but I haven't had this problem. The best I can do is give you a web site I found regarding the 6XAS.

http://www.futabarc.com/faq/faq-6xsuper.html

smokingcrater

trev doesn't reverse the throttle, only where the trim is active...

http://www.futabarc.com/faq/faq-6xsuper-q94.html

FlyerBry

My Feedback: (8)

This is exactly what I thought. This is why after reading the manual I made the switch on the TREV menu. If the only change was to be the trim position then why did the engine fire up at full throttle??? No only did the trim change but the direction changed as well.

From what you have said it supports my original thinking that the TREV setting should have fixed the problem. I'll have to give it another try and see if I can get it straightened out. At least it seems my thinking was right so I will have a better idea of the changes I am making when I try it again.

CrashBurn69

My Feedback: (1)

Did you try the seperate servo reverse, besides the Trev. I think you might need to do the servo reverse and the trev. That way it will be closed when the throttle stick is down, and would put the trim on bottom half of the stick.

J.Paul Saure

Just to be clear:

1- The TREV function specifies if you want the trim lever to work on high throttle or low throttle. Set it so it works on low throttle and you can adjust the idle and shut down the engine with the trim lever.
2- The REV function specifies if you want the throttle open with stick forward or back. Around here (and it seems everywhere) the standard is full throttle=forward stick.

OK, now for your question, and what I think you are trying to explain/ask:
Yes, I've seen that most engines are more sensitive to the "first halve" of the throttle control. To make the throttle more "linear", or even make it a little more delicate around idle, you need NEGATIVE EXPO on the throttle channel. I use around -20% to -30% depending on the plane and engine. Check it out, maybe you dialed POSITIVE EXPO on the throttle (that would make the throttle around idle even more sensitive!). The same goes for the other channels, you need NEGATIVE expo to make the controls work smoother, not positive expo!

One last thing: Throttle EXPO works from one end of the throttle stick (same side as the throttle trim selected on TREV), while on the other channels (aileron, elevator, rudder) it works around center stick.

The 6XAS is a great radio! I've seen a lot of people buy it and never use the 3 channel dual rates or the 4 channel EXPO!!!!!! (those were the main reasons for me to buy it)

ifixairplanes

My Feedback: (9)

i use 3 chan D/R on 1 switch and also have all 4 expos set up...not mention the great mixing features. i have a lot of fun with this radio programming in different mixes and switches for my funtana!

sean

FlyerBry

My Feedback: (8)

Thanks for the input. I do love this radio, the more I use the special features the happier I am with it. In this case I am pretty comfortable with the fact that the problem isn't with the radio but the doofus pushing the buttons. Checking the Expo is a good thought. I originally wondered to myself if there could be something else I could be setting since this radio does have so many nice features.

I tend to think my problem lies in how I had set the TREV setting or something along those lines so I am going to give that another try to see if maybe I just did something wrong the first time - especially since I was spending more time adjusting the engine than worrying about the radio settings.

laryboy

My Feedback: (2)

try this http://www.futaba-rc.com/faq/faq-6xsuper-q94.html

tande

My Feedback: (48)

J. Paul Saure is right---Go to your "Expo" screen on channel 3---