Differential ailerons on XL

[Arcane]

Has anyone tried using differential ailerons on their XL?

[Steve]

Has anyone tried using differential ailerons on their XL?

A LE builder /flyer used the DE differential bellcrank and liked the control balance...

[Aerodude45]

I was actually thinking of trying that too, by shortening the length of one side of the aileron bellcrank slightly so that the ailerons deflect upward more than they do downward for a given deflection of the stick. I don't know how much to shorten it from the length specified in the plans, or what the differential should be in degrees, at max deflection.

[Steve]

I was actually thinking of trying that too, by shortening the length of one side of the aileron bellcrank slightly so that the ailerons deflect upward more than they do downward for a given deflection of the stick. I don't know how much to shorten it from the length specified in the plans, or what the differential should be in degrees, at max deflection.

DE bellcrank sheet attached:

[scottiniowa]

I was actually thinking of trying that too, by shortening the length of one side of the aileron bellcrank slightly so that the ailerons deflect upward more than they do downward for a given deflection of the stick. I don't know how much to shorten it from the length specified in the plans, or what the differential should be in degrees, at max deflection.

     One of the rules we follow in doing CAD work,
Step 1- is knowing what you want to achieve
Step 2- then drawing parts to do/achieve step 1 
Step 3- the beauty of CAD in 3D, is you can fully test in movement, step 2, to know if you thus created what you wanted in the first place.

I know this seems like a play on words, but it really is a basic method…of some reverse engineering.  i.e., know what you want to get to in the end, precedes knowing how to make the parts.

If  you come up with a known end result you want, I could easily do the 3D cad test to make sure the numbers are doing what you want or producing your desired movement.  All before a single part is made.

Best of success

[Bob Wood]

After discussing it on this forum last year I went with the DE bellcranks, for diff throw.

Turned out well. looks like it does what I was after, more up than down....
I have never flown the stock ones so I cannot tell you the effect this has had. I am still in the pattern test phase of my XL so I will have more comments when I get my broken lower mount bolts fixed and resume flying (see 1/2 VW section on this forum) for that conversation.
Bob

[scottiniowa]

After discussing it on this forum last year I went with the DE bellcranks, for diff throw.

Turned out well. looks like it does what I was after, more up than down....
 
Bob

Now would be the perfect time to say what you ended up with,   i.e.  Max up is  X degrees - Max down is X degrees   with neutral when the ailerons are in the same plane as the balance of the wing.   Digital level or even your cell phone level can tell us.

Scott

[Bob Wood]

Sorry been gone will measure this and report back this week.
Bob

[Bob Wood]

I took measurements over the lunch hour. 21 degrees up and 15 degrees down.
Left and right wing only differed by 1 degree.

I used the Double eagle bell-crank drawing to the plans exactly.
I am in the middle of flight testing and will know better with a few hours under my belt how it feels differential yaw wise. 

I had some bugs to correct and will get back to it shortly.

CANT WAIT!!!! It is really fun!!

Bob

[dz1sfb]

I was actually thinking of trying that too, by shortening the length of one side of the aileron bellcrank slightly so that the ailerons deflect upward more than they do downward for a given deflection of the stick. I don't know how much to shorten it from the length specified in the plans, or what the differential should be in degrees, at max deflection.

 DE bellcrank sheet attached:

Steve,
I am interested to know why the control cable position is behind the pivot axis of this  bellcrank? This would cause fore/aft movement of the cable as the control stick is cycled through its range of motion, and uneven cable takeup away from center stick position.

Not sure this is a problem, but seems like we are loading the system. Maybe this is intentional.

Ken

[Steve]

I was actually thinking of trying that too, by shortening the length of one side of the aileron bellcrank slightly so that the ailerons deflect upward more than they do downward for a given deflection of the stick. I don't know how much to shorten it from the length specified in the plans, or what the differential should be in degrees, at max deflection.

 DE bellcrank sheet attached:

Steve,
I am interested to know why the control cable position is behind the pivot axis of this  bellcrank? This would cause fore/aft movement of the cable as the control stick is cycled through its range of motion, and uneven cable takeup away from center stick position.

Not sure this is a problem, but seems like we are loading the system. Maybe this is intentional.

Ken

Ken:
Over the life of the DE design I have in particular solicited builder/flyer feedback and have had only positive feedback on the aerodynamic effect of these bellcranks and no input regarding cabling issues... The bellcrank is from the DE package and has been also used on LE & XL... The cable paths are long in comparison to the small change in system length between stick & aileron and there is natural flexing going on in structures between the fixed points... This is ofcourse notice to just take the slack out of the cables when you are adjusting them and do observe the cable tension as you run the range of motion into the controls...

BTW: If you look at Eagles running the extruded alum hinges on the elevator or rudder you will see other cable tensioning anomalies in the cabling system - a caution to run the cable driven systems thru a full range of motion whilst adjusting cable tension...
Steve

[joecnc2006]

Do you have a source for the bearing used?

[dz1sfb]

Do you have a source for the bearing used?

Wicks apparently has them, though they don't quite look as pictured.

Ken

[Vince Carucci]

I took the previous question to be:  

"Do you have a source for the bearing which are being used?"

That changes the question significantly, though your answer is probably still appropriate.

The history and mystery of the English language!

[Tom XL-7]

I am not sure what the problem was on the cable tension deal. There would be a minimal difference because the line through the cable holes does not go through the pivot point. 
This would be more of an issue on some type of solid pushrod type control than with cables. If it really bothers anyone move the cable holes forward or the pivot back in line.
Why is it this way? the way it is drawn uses less sheet stock and as such is lighter. But to put little balls on the ends to allow cable holes to move forward or a part of a circle in the center for the pivot to move back would be minimal. Instead of a "T" shape, the cable arms could simply be angled forward. 
Any way you modify it keep your center to center distances the same. You are already changing one ratio probably don't need to change the others.
Reminds me of "marksmen" who sight in by adjusting after every shot. or the fellow who fires a new handgun and doesn't do to well. Next time you see him he has new grips, new sights, a Magna-ported barrel and different loads just for extra accuracy. Why not throw some gloves in there too brother! 
 Off topic point being you don't want to chase a bunch of things around.
Tom XL-7