Flaperon travel parameters


17 posts in this topic

Posted

I find that my Avid Bandit seems to lack adequate roll control, particularly in a crosswind.  I have been unable to pin down exactly how much travel from up to down with full stick deflection the flaperons should have.  Does anyone have the actual degrees of travel and how to adjust them available?  

Thanks in advance,

Jim Bowerman

viejopilot@gmail.com

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Posted

You referring to crosswind landings or crosswinds while flying. My Kitfox model 2 has approx. 20 deg up and down travel. Max crosswind component is 15 kts.

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Posted

Avids and kitfoxes demand a lot of rudder use doe to adverse yaw with the original mixer system.  Do you have the updated F7A control arms in the mixer?

When in a good crosswind I limit the flap use as well.

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Posted

Flapperons should travel plus and minus 25 degrees limited by the bottom of the stick hitting both sides the little triangle pouch it lives in. pulling full flaps should displace the flapperons an additional 15 degrees down and not cause any bind in the initial flapperon travel described above. So, with full flaps pulled and full aileron in one direction or another, max down deflection should be 40 degrees. THIS SHOULD ALL BE ABLE TO HAPPEN WITH WITH NO BINDING OR TRAVEL LIMITING EXCEPT AT THE BASE OF THE STICK which is the travel limiter.

Hope that makes sense. :-)

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Posted

Crosswinds while flying seem to be the problem.  A gust puts a wing down and until that gust subsides the full deflection will not raise the down wing.  My Avid also has about 20 degrees up and down travel.

Thanks for your input Allen,

Jim Bowerman

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Posted

I spoke again with the test pilot and I was incorrect about when the problem occurs.  It is when flying, not landing, that it happens.  When a gust lowers a wing it is difficult to impossible to pick it up with full deflection until the gust subsides.  I apologize for the misunderstanding and thank you for your help.

Jim

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Posted

The complete build manual including rigging is located in the link above.  Without the F7A mod, you probably have more up travel than down on the roll input.

With mine, when I pull in full flaps I get very little addition "down" movement on the flaperon but the other side goes up as usual.  

These birds are pretty responsive in roll control.  If he can't level a wing something is loose and flopping.  Check the rib tails and the complete system for slop.  I have only been in one situation where I could not level the wings with just the stick and that was in a nasty mountain rotor.  You can fly the plane with rudder alone so if he can't keep wings level something is wrong in a big way.

I am not sure how Chris is getting 40 degrees down on his bird, I can't even come close to that on mine.  That seems to me like your getting well into roll reversal territory where the drag of the down can't be overcome by the opposite side going up and you roll in the opposite direction you intended.

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Posted

It's only 40 degrees down on the "down" aileron. It will be approx 15 degrees up on the other one at full deflection. I got these numbers on every Avid I have owned My original MKIV got those numbers, My Magnum was identical, and my Fat Avid once all put together came up with exactly the same deflections. That's how I got the numbers. I seldom use a lot of flaps, but in a lot of Avid time, I have never experienced roll reversal, but I have heard of it happening. I also have no experience whatsoever with the F7 mod. Maybe that makes things move too far

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Posted

The MK IV has the F7A arms I believe.  Now I am going to have to measure mine again when I have it in the shop next week.

:BC:

 

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Posted

In most of the older aircraft I have flown, they normally would not level back out with just aileron control when upset by a gust. It always took help from the rudder to straighten things back out.  This was in Champs, T-crafts, and such.  It seems instinctive to use ailerons only and in minor gust it does work, but it was beaten in to me to use rudder when using ailerons. But some were taught differently.

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Posted

In most of the older aircraft I have flown, they normally would not level back out with just aileron control when upset by a gust. It always took help from the rudder to straighten things back out.  This was in Champs, T-crafts, and such.  It seems instinctive to use ailerons only and in minor gust it does work, but it was beaten in to me to use rudder when using ailerons. But some were taught differently.

Agreed.  If you use one, you automatically use the other.   Rudder/aileron interconnected airplanes make one pretty lazy.  It would take some big rotor type winds to keep me from being able to level my Avid or any KF I have flown to date.  Either they guy is not moving the stick to full deflection or not using his feet.  If he is then there is something wrong in the control system or structure.

 

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Posted

Just a silly question here...maybe your pilot has big thighs, in that case, it is possible to have aileron movement restriction to the left (stick butting against leg).

Just thinking outside the box.

L.W.

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Posted

The control system on an Avid/Fox isn't that complicated but there are places that can cause problems. Rod ends binding, hitting other parts, etc. Clearances are in close quarters with other parts and structure. A good hands on inspection usually solves the issue if there is one. A copy of the control system diagram helps if one has it. Something so simple as a bolt inserted the wrong direction  can cause problems. Little building errors by the original builder can be issues later on. Maybe the original builder never flew in gusty conditions and wasn't aware of any problems.

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Posted

The control system on an Avid/Fox isn't that complicated but there are places that can cause problems. Rod ends binding, hitting other parts, etc. Clearances are in close quarters with other parts and structure. A good hands on inspection usually solves the issue if there is one. A copy of the control system diagram helps if one has it. Something so simple as a bolt inserted the wrong direction  can cause problems. Little building errors by the original builder can be issues later on. Maybe the original builder never flew in gusty conditions and wasn't aware of any problems.

Absolutely! Every one of my Avids had the issues you describe above. Once full travel is obtained by fixing all the little builder induced issues the travel is what it is by design and won't vary from plane to plane.

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Posted

The MK IV has the F7A arms I believe.  Now I am going to have to measure mine again when I have it in the shop next week.

:BC:

 

I do not believe MKIVs came with F7s. My MKIV was a late sn very much built to plan and it did not have them. I guess I didn’t know that any avids came with them. I thought it was a part you could buy as an extra if you did not want to use the rudder. I always believed that having full differential travel provided the greatest authority even though it required more rudder input to stay coordinated. I don’t think any of my avids have F7s from the pictures I have see on this site.

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Posted

I find that my Avid Bandit seems to lack adequate roll control, particularly in a crosswind.  I have been unable to pin down exactly how much travel from up to down with full stick deflection the flaperons should have.  Does anyone have the actual degrees of travel and how to adjust them available?  

Thanks in advance,

Jim Bowerman

viejopilot@gmail.com

Check tips here -> http://avidfoxflyers.com/index.php?/topic/595-kf-iii-rigging/&do=findComment&comment=3413

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Posted


Your bandit has the f7a mods, and is/was set, with flaperons fully down, to have a negative reflex, which gives it a bit more speed in cruise but makes the plane handle, as I put it, "like balancing on a ball".  Add a bit of flaperon, and you should notice a marked difference in handling while maneuvering.  Early avids/foxes didn't have a trim- they adjusted flight control feedback through modification of the flaperon settings.. Messing with the flaperon adjustments is not something I'd recommend, The 2-3 degree negative setting is mentioned in the builder's manual as an option.

I'd responded to your earlier thread on CHT settings for your Jabiru, but I don't think you ever went back to that thread.. you might want to look at my response :-)

 

Jack

Austin, TX

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