I just recently completed a Sig Mayhem 40, and while I was setting up the radio I noticed that Sig recommends - 70% expo on the ailerons and rudder and -50% expo on the elevator. At first I thought this just meant add 70% and 50% but I noticed my radio can be set to a negative percentage. Does this sound correct? If I set the expo with a negative percentage then almost all of the control throws will be obtained with very little stick movement. Most other planes that I have are set up with positive expo, but none have been 3D planes. What do you guys think?

Negative exponent is the opposite. The control won't be as "twitchy" as the stick movement. I own a Mayhem 40 as well and love it. I could go look at my radio, but I believe I have no expo on low rates and somewhere around -40 for high rates on the ailerons and elevator. You can never have too much rudder, thus no expo! Hope you enjoy it.

Thanks, Squeaky Penguin.

What motor are you running on your Mayhem 40? I have an Evolution 46 on mine right now but I am considering a Saito 4 stroke.

I beleive Futaba and Jr use opposite parameters for their expo.

If you go to the positive on a Futaba it will be more sensative so you want -70% and so on.

It depends on what brand radio you use.


John

Wahoo, that makes since. I am using a Spektrum which should be the same as JR.

Sorry, I'm using a Futaba radio and didn't realize they are different. I'm running a OS FL-70 four stroke with a Zinger 14x4 prop. It's not very powerful but thats most likely because of the 7,000' of elevation. Hovers right below full throttle.

Squeaky Penguin,

I am considering a Saito 72 for my Mayhem. The Saito weighs less than the Evolution 46 that I am using now, so power to weight should be good. I am at 600 ft above sea level. Do you think this would be a good match for the Mayhem?

If you don't already have the 72 I would go bigger. Maybe an 82 or even a 90. At one point I considered putting in the Saito 115 thats in the same crankcase as the 91 but spent the money on another project. As they say, there's no replacement for displacement.

I have read a few other posts that say the 82 is a good choice.