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Flaperon setup

#21
With expo, you don’t get more control throw than you would without it. Expo just softens stick input at the center - to lessen over-controlling - as long as you don’t automatically defeat the point of expo.
Yes, I understand this. But with expo, basically if the stick is less than half way to full, the curve is "softened", but once it passed half way, the curve is "hardened" instead. So when this softened half is not enough, we have to go cross the half way and get into the hardened part.

Of course this probably mean I should physically increase the aileron throw so half of the aileron throw can be enough to do most of the newbie needed to do, but I am just saying it depends on the particular plane. Basically if a plane's aileron authority is weak, then increasing expo may cause pilot to over control it.

Well, correction: maybe not exactly "half way" but there is a point that the curve turns from "softened" to "hardened". If the throw at that point is still not enough to make the expected movement, then it is going to be in trouble because we are getting into the harder part of the curve.
 
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#22
Thanks for these suggestions Litterbug and CappyAmeric. I'll try channel 6 if I persist with flaperons. The reason I was interested in this option was that I was worried the plane would have a tendency to dive towards the ground, which turned out to be correct - I had to use full up elevator trim on the first flight. However I'm now thinking the root problem is the tailplane incidence being too high, so I'm considering cutting through the glue to remount the tailplane with some packing on top of the LE. Wing and tailplane incidences were a guess given that I'd changed the wing section compared to the Tiny Trainer it was based on.
In terms of the twitchy controls, I've now reduced the throws and have 30% expo - like MachineCat, I'm a bit wary of going too far with expo partly due to lack of familiarity with higher settings and partly because I keep telling myself I should learn to control my own inputs on the sticks better. Wind forecast is too high for me over the next few days; I think I'll wait for dead calm before trying these changes!
 

Matthewdupreez

Legendary member
#23
Thanks for these suggestions Litterbug and CappyAmeric. I'll try channel 6 if I persist with flaperons. The reason I was interested in this option was that I was worried the plane would have a tendency to dive towards the ground, which turned out to be correct - I had to use full up elevator trim on the first flight. However I'm now thinking the root problem is the tailplane incidence being too high, so I'm considering cutting through the glue to remount the tailplane with some packing on top of the LE. Wing and tailplane incidences were a guess given that I'd changed the wing section compared to the Tiny Trainer it was based on.
In terms of the twitchy controls, I've now reduced the throws and have 30% expo - like MachineCat, I'm a bit wary of going too far with expo partly due to lack of familiarity with higher settings and partly because I keep telling myself I should learn to control my own inputs on the sticks better. Wind forecast is too high for me over the next few days; I think I'll wait for dead calm before trying these changes!
you'll also want to check your cg... if you are too nose heavy it will want to nose dive...
 
#24
Yes, I understand this. But with expo, basically if the stick is less than half way to full, the curve is "softened", but once it passed half way, the curve is "hardened" instead. So when this softened half is not enough, we have to go cross the half way and get into the hardened part.

Of course this probably mean I should physically increase the aileron throw so half of the aileron throw can be enough to do most of the newbie needed to do, but I am just saying it depends on the particular plane. Basically if a plane's aileron authority is weak, then increasing expo may cause pilot to over control it.

Well, correction: maybe not exactly "half way" but there is a point that the curve turns from "softened" to "hardened". If the throw at that point is still not enough to make the expected movement, then it is going to be in trouble because we are getting into the harder part of the curve.
Increasing aileron throw will worsen over controlling.

If you want to experiment, set up dual rates. Newbies should usually think about using a 70% low rate and 30% expo just like FT recommends for most of their plans and kits.
 
#25
you'll also want to check your cg... if you are too nose heavy it will want to nose dive...
Yep, good point. At the moment it's right at the point specified for the Tiny Trainer; it could probably go back a little for this type of plane but I'm a bit scared to experiment until I get more used to flying it!
 

Bricks

Master member
#26
Every plane I own has 3 rates low medium and high rates, and each has there own expo ratings. Usually my low rates will carry 30% expo across the board and 50% throws on the ailerons and 65% on the elevator and rudder. Medium rates will carry 30% on rudder and elevator and ailerons will carry 40% with 75% throws on the elevator and rudder and 75% on the ailerons. High rates will have 100% throws across the board with 40% expo on the rudder and elevator and 60% on the ailerons, all set on 3 position switch. These setting will vary some depending on the type of plane but are all pretty close to these settings. The depending part is how the plane reacts to these settings example some planes will not have a lot of authority from the ailerons then my percentage of aileron throw will move up, or vice a versa some planes have wild aileron control so my throw on the lower rates will be lower and expo will go up.
 
#27
Increasing aileron throw will worsen over controlling.

If you want to experiment, set up dual rates. Newbies should usually think about using a 70% low rate and 30% expo just like FT recommends for most of their plans and kits.
Totally agree with you with regarding the FT pre-verified plane plans. But again I was thinking about something different.

Assume one kind of FT planes can make a decent turn with 30% (not real data, just example) of the aileron full throw, so having the curve soften between 0% to 50% will make the control a lot easier, that is for sure.
But now if I made a plane which will make the same turn only with 70% of the full throw. In this situation, to make the same turn, I will have to operate at the more steep part of the curve, which would make it harder for me to control, because at that position a little bit of stick movement will result in big aileron position change

The positive expo is to make the control easier for lower end, with the cost of harder at the higher end. So the assumption here is that the lower end is enough for most wanted action. But if this assumption is not true, then it is a totally different story.

More thinking into this: if I always need the aileron to do 70% throw to make a decent turn, then in this situation actually a negative expo may make more sense.
Even more thinking: no, a negative expo may be better to make that turn, but will be harder to get it back to neutral position. So basically the design of this aileron is not good enough, I admit that. :D
 
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Bricks

Master member
#28
Totally agree with you with regarding the FT pre-verified plane plans. But again I was thinking about something different.

Assume one kind of FT planes can make a decent turn with 30% (not real data, just example) of the aileron full throw, so having the curve soften between 0% to 50% will make the control a lot easier, that is for sure.
But now if I made a plane which will make the same turn only with 70% of the full throw. In this situation, to make the same turn, I will have to operate at the more steep part of the curve, which would make it harder for me to control, because at that position a little bit of stick movement will result in big aileron position change

The positive expo is to make the control easier for lower end, with the cost of harder at the higher end. So the assumption here is that the lower end is enough for most wanted action. But if this assumption is not true, then it is a totally different story.

More thinking into this: if I always need the aileron to do 70% throw to make a decent turn, then in this situation actually a negative expo may make more sense.
Even more thinking: no, a negative expo may be better to make that turn, but will be harder to get it back to neutral position. So basically the design of this aileron is not good enough, I admit that. :D



Expo has more to do with the speed of the plane that is why I want higher expo at more throws so when I get into the throttle hard ( speed ) it needs less throws to control the results ( expo softness around neutral ). So if I come down the runway at a very fast speed and want to pull up into a quick hover ( where I need max control throws ) I do not need to keep switching rates. Low expo and high throws at speed can create real problems, for me it is just easier to keep my plane flying more smoothly then herky jerky by over controlling in different situations.
 
#29
Expo has more to do with the speed of the plane that is why I want higher expo at more throws so when I get into the throttle hard ( speed ) it needs less throws to control the results ( expo softness around neutral ). So if I come down the runway at a very fast speed and want to pull up into a quick hover ( where I need max control throws ) I do not need to keep switching rates. Low expo and high throws at speed can create real problems, for me it is just easier to keep my plane flying more smoothly then herky jerky by over controlling in different situations.
totally agree, with high throw there should be higher expo. low expo and high throws is going to be bad.
My concern is about when the throw is too low physically, in that situation, I think it is a different story.
 

Bricks

Master member
#30
totally agree, with high throw there should be higher expo. low expo and high throws is going to be bad.
My concern is about when the throw is too low physically, in that situation, I think it is a different story.

Correct and the reason I use 3 rates and will make changes to how much throw is involved for each control surface in each rate, this all comes down to specific planes, nothing is written in stone I have a few 3D planes that need 100% expo with 100% throw, if flying any faster then harrier.
 
#31
Try using channel 6 (flaps) instead of channel 5 (gear) for the second aileron channel when using the flaperon wing type.

Hi LitterBug,
I worked out what I was doing wrong. When I went to Channel Assignment I was looking at the default screen which is Channel Input Config, and didn't realise there is a separate screen for RX Port Assignments. When I went to that screen, it had left aileron on port 6 not 5. When I changed this to port 5, the flaperons worked fine!
Thanks again for your help