SoCalSal

My Feedback: (16)

Can someone explain to me what "Expo" is on a trans and what it does?? Also The proper use of it. I have asked a few of the locals and I have heard a few different answers. I just want to know the proper answers.
Thanks Much.

firstplaceaviator

My Feedback: (27)

Expo is just as the name suggests. The servo moves "exponentially" with the stick. It is mainly used to make the Tx sticks less sensitive around the neutral points.

Without Expo, when you move the aileron stick 25% of it's travel, the servo will move 25% of it's travel. With Expo, when the stick is moved that same 25%, the servo will only move say, 10% of it's travel. As you move the stick to full travel, the servo still moves to it's full travel. Make sense?
Doug

Birman

Expotential is normally used to control the sensitivity of the sticks around neutral. By putting in Expo, you can make the stick(s) more or less sensitive around neutral. For example, if you pull back on the elevator stick a little while trying to flair on landing and the plane jumps back into the air, try putting in around 30% expo (see your manual for either negative or positive expo for your brand of transmitter) and try again. You may want to put in more or less expo until it feels right to you. Hope this helps.

LesUyeda

Softening the response around neutral also has the advantage of decoupling controls; i.e. give full right aileron, and I always get a touch of elevator, just because of the geometry between hands and transmitter. Expo does away with that. You have full throw when you want it, and less when you want that, without having to throw a switch for dual rates.

Les

WMB

My Feedback: (1)

My Sig Kobra is real twitchy on ailerons at low speed while landing, don't want to cart wheel it! I could mechanically reduce the throw to get rid of the twitchiness, but then roll rate would be slow while flying. I dialed in -35% expo which gets rid of the twitchiness, but still gives me full throw and roll on the ailerons.

SoCalSal

My Feedback: (16)

Thanks..this is what some of the guys have said..but others had a different answer.

Rodney

Just remember, Hitec and Futaba need negative expo, JR and Airtronics need positive expo to do the same thing. Put in the wrong one and things get very interesting.

SoCalSal

My Feedback: (16)

I use a Multiplex.they are negitive I think. If I want 70% expo I turn down the values to 30%.I think. I need to slow down my stick rates till I get more time on them. I'm just starting to fly a Yak 54 and it is VERY responsive to any inputs and I have "Heavy Thumbs" at this time.

LesUyeda

The way that I would find out: Put in as much expo as you can; move the stick slightly around zero, and see what the control surface does. If it moves hardly at all, you have the right sense; go back in and set your first try value.

Les

SoCalSal

My Feedback: (16)

Great Idea...........Thanks

firstplaceaviator

My Feedback: (27)

I'm just curious, What were some of the other explanations you got?

With my Futaba 9CHP for 3D airplanes, I use (-) expo on elevator and ailerons. But, I use (+) expo on rudder in order to get immediate rudder response during thrust vectored maneuvers.