Eagler's Nest
Airframes => Single Seaters => XL => Topic started by: Arcane on July 07, 2015, 06:50:02 PM
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Has anyone tried using differential ailerons on their XL?
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Has anyone tried using differential ailerons on their XL?
A LE builder /flyer used the DE differential bellcrank and liked the control balance...
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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.
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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:
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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
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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
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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
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Sorry been gone will measure this and report back this week.
Bob
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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
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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
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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
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Do you have a source for the bearing used?
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Do you have a source for the bearing used?
Wicks (http://aircraftproducts.wicksaircraft.com/item/grease-fittings-bearings/bellcrank-bearing/bc5w11) apparently has them, though they don't quite look as pictured.
Ken
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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!
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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
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Joe, the part# is 05-03451 bellcrank bearing from Aircraft Spruce. I just built mine last week.
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Joe, the part# is 05-03451 bellcrank bearing from Aircraft Spruce. I just built mine last week.
Thanks, Like to see some pictures of yours also. I image they are mirrored.
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Has anyone tried using differential ailerons on their XL?
A LE builder /flyer used the DE differential bellcrank and liked the control balance...
[font='Segoe UI', 'Helvetica Neue', 'Liberation Sans', 'Nimbus Sans L', Arial, sans-serif]What is the advantage of using differential ailerons? ([/font][/b][font='Segoe UI', 'Helvetica Neue', 'Liberation Sans', 'Nimbus Sans L', Arial, sans-serif]more up than down)? [/font][font='Segoe UI', 'Helvetica Neue', 'Liberation Sans', 'Nimbus Sans L', Arial, sans-serif]Is there a better role rate?[/font][/u][font='Segoe UI', 'Helvetica Neue', 'Liberation Sans', 'Nimbus Sans L', Arial, sans-serif] Lighter stick feel?[/font]
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Has anyone tried using differential ailerons on their XL?
A LE builder /flyer used the DE differential bellcrank and liked the control balance...
[font='Segoe UI', 'Helvetica Neue', 'Liberation Sans', 'Nimbus Sans L', Arial, sans-serif]What is the advantage of using differential ailerons? ([/font][/b][font='Segoe UI', 'Helvetica Neue', 'Liberation Sans', 'Nimbus Sans L', Arial, sans-serif]more up than down)? [/font][font='Segoe UI', 'Helvetica Neue', 'Liberation Sans', 'Nimbus Sans L', Arial, sans-serif]Is there a better role rate?[/font][/u][font='Segoe UI', 'Helvetica Neue', 'Liberation Sans', 'Nimbus Sans L', Arial, sans-serif] Lighter stick feel?[/font]
Differential ailerons attempt to reduce the adverse yaw effect when using ailerons to bank the wing. In general the aileron moving down creates more drag than the one going up, which pulls the airplane out of the turn if not corrected with coordinated rudder. With differential the down movement is reduced while the up movement is increased to get a similar roll rate but without as much drag and adverse yaw. In theory if you get the differential just right you would not need to add rudder correction when rolling.
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On high-performance aircraft, It may be fair to say they need differential ailerons. On the slow and low XL I feel it's a mixed bag. The offending drag is then corrected with yet more drag from the rudder. Drag reduction is a reasonable goal as is an easier to control aircraft. But I am giving up some roll rate I may need at slow speeds and landing. Perhaps I should just learn to use the rudder. It is normal practice in stick and rudder piloting.
I don't think it is a big deal one way or the other. The beautiful thing with these aircraft is how freakishly exposed everything is. Don't like it - change it out.
Tom XL-7
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i am pleased with how my ailerons function with differential throw on a legal eagle. my plane flys great without much thought of rudder. bearings were purchased at airventure from one of the hardware booths. my arms were riveted one hole off of 90 degrees so they could be put back to factory spec if needed.
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Like the picture above, does anyone see any problem with making the pivot point of the bellcrank inline with the cable attachment points?
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We put the pivot point in line with the cable attach holes on the LEU and DE bellcranks. Only made sense to me. Less variation of resulting cable length changes (stretching/loosening) that way. Worked fine.
We also put the differential type bellcranks on the LEU, where the plans showed the square T design, if I remember. Worked fine.
The DE has the differential type per design, works fine.
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Like the picture above, does anyone see any problem with making the pivot point of the bellcrank inline with the cable attachment points?
I used the Sam (LEXL A58) design. See photos. Haven't flown yet. Shooting for this summer. This arrangement can easily be modified later on if I want differential ailerons by drilling out the rivets and shifting around one rivet hole.
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I just wanted to add something on this subject after I had flown my XL more. I wanted Diff aileron bell cranks and just used the plans for the double eagle. I pressed a simple bearing sleeve into the bellcrank and it flies great, and minimal weight.
I can do a nice turn with minimal rudder, and have no problem keeping the ball centered with this set up.
It is not like you are going to wear these bearings out. You move the stick very little!!
I just have a hand full of flights now and really am having fun.
My 2000 hours are in my Tripacer and other trikes. I have 2 hours of tailwheel time i did 10 years ago and had no trouble landing or taking off this little bird.
My tripacer is very high drag high sink..I feel right at home in this XL.
Leonard congrats!! A great little airplane.
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Like the picture above, does anyone see any problem with making the pivot point of the bellcrank inline with the cable attachment points?
That's where the pivot point is supposed to be! In between and inline with the cable attach points.
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Passing question here: Was curious why the aileron cables weren't run within the wing like on the Champs? Building my DE per Leonard's designs but curious just the same. Any thoughts?
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Passing question here: Was curious why the aileron cables weren't run within the wing like on the Champs? Building my DE per Leonard's designs but curious just the same. Any thoughts?
Years ago Leonard said he "saw this on an English ultralight and liked it."... I think that was in one of his videos.
It does make it easy to inspect and maintain.
I think cubs have similar, but with the balance cable returning in the wing.
You see that below. Also why you should expect the unexpected when hand propping...
https://www.youtube.com/watch?v=fqiBb98o1D8