EDF expo

[purduephigam]

I've gotten some great feedback on my super newb thread and just wanted a little input on this so I can wrap my head around it. Do you all use expo with your EDFs? I'd imagine this varies on skill level and comfort; but say you maiden a new jet, are you programming expo then backing off as you see fit? Or do you just program by the book and forget the expo?

[xviper]

I put in 30% expo on high rates and maybe 20% on low rates and in between for mid-rates for the maiden. It depends on the plane. I'll do the first take off, trimming flight in mid-rates and adjust to high or low rates during the first circuit. Trim it at cruising speed into the wind. After I land, I'll adjust all the rates/expo according to how it felt so that the general flying is done on mid-rates for each control surface. I may increase or decrease for each. There are no set rules. What works for me may not work for the next guy.

[dahawk]

I use a lot of expo on twitchy jets. 40% on ailerons and elevator usually. All it does is smoothes out the stick around its center. Maybe dampens response but makes flying more relaxing.

[fhhuber]

How much expo depends on how the model flies and personal preference.

If you find you almost always use 30% expo, then test fly new models at 30% expo.
Just about always using the same expo means you have a tendency to move the stick a certain minimum amount around center. Once you have that habit, its hard to change.

The real issue with moving from a trainer or mild sport aerobatic to MOST EDFs is speed. The EDFs tend to need more speed to stay in the air. (there are some notable exceptions) they tend to have high top speed. They also are often much heavier for the size due to the weight of the EDF "shroud" This means you need to be able to keep up with the faster airplane. Many have very low wingspan relative to wing area and thus have high roll rate and sensitive ailerons.

There is also something EDFs do more noticeably than "conventional" prop driven planes. You can "stall" the fan by applying power too fast. A very high rpm, high pitch prop of any type will stall its blades at low airspeed. A huge prop disc tends to hide this. The EDF does not have the disc area to hide it.
Tie the tail of any model to a fish scale and slowly advance throttle. You will almost certainly find that as you exceed a certain throttle setting that the pull measured by the fish scale will go DOWN suddenly. That is when the prop stalled. Remember that throttle setting for your EDF. That is max throttle for takeoff until you have gained some speed. You can often take off in HALF the runway using half throttle as full throttle.

[dahawk]

Here is a good explanation on how to apply expo. For the longest time, I didn't realize there's a coupling effect when using too much. My planes have been set up to be too mushy. Mushy is bad. Look at Captain Mike's vid.

https://youtu.be/84vRkQvEJGg

[purduephigam]

Here is a good explanation on how to apply expo. For the longest time, I didn't realize there's a coupling effect when using too much. My planes have been set up to be too mushy. Mushy is bad. Look at Captain Mike's vid.

https://youtu.be/84vRkQvEJGg

I've seen this before and think it's an excellent video for the beginner as well as the advanced. Just offers a lot of perspective. I'll need to train myself to make more polished movements but expo certainly aids me in that I'm not involving other surfaces.