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Balanced my ailerons tonight... or should I say found out they were already balanced. I hung them next to each other (using ratchet straps to control height and kite string through the hinge pins), leveled them in all directions along the tops, then inspected their hang relative to each other. I could not detect any difference between them, so I guess they're all set! Hooray for no more drilling in lead!

Aerobatic ailerons. Plans call for them to hang the same relative to each other (versus standard ailerons, which balance each individually to hang along a level plane.)

For size reference, in the first picture you can see the small drive horn sticking out of the back of the aileron... that's where normal ailerons would end. Quite a bit more skin and another rib on the aerobatic (plus the drive horn gets 2 ribs rather than 1. Apparently that's a lot more weight versus the same counterweight lead.

Thanks for the pics Ryan! Very precise job; I can only hope mine will turn out that nice! :D

Looks good but maybe someone can explain something to me. Why do the acro ailerons get balanced so differently than the normal ailerons. The only difference is that they are about 16" longer. The regular ailerons have to be balanced so the bottom edge is within a certain measurement of level. The acro version seems to have the trailing edge hang down much lower probably because the counterweight isn't big enough to compensate for the extra weight. I'm sure it is fine but I don't understand why it is so critical to get the counterweight perfect on the normal ailerons but on the acro version the two ailerons just have to match each other. Anybody know the reasoning behind this?

Ketih
#554

I'm not sure, other than to say that after having done this exersize, I think the method for balancing the normal ailerons is probably easier. There was a lot of swaying and whatnot doing this, making the ailerons level to each other took a long time with all the movemenent (lots of miniscule adjustments to the straps), I'm glad I didn't actually need to make any changes to the weights. Seems to me it would have been quicker/easier if all I had to do was level the bottom of each aileron individually. And once they're both levelled, you know that if you put them into a rig like mine, they would also be equal, so you've saved yourself that step.

I sent these photos to Kerry and he confirmed that this was a good result.

Its possibly easier to check balance by mounting the aileron to the bench by clecoing a piano hinge to the bench.

I am no aeronautical engineer but I thought the point of balancing the ailerons was for flutter resistance. Not to just make the pairs equal in balance, in comparison with each other.

I am doing some aerobatic training at the moment and was thinking of swapping mine over to aerobatic ailerons.

Steve
Sonex 892

sonex892 wrote:I am no aeronautical engineer but I thought the point of balancing the ailerons was for flutter resistance. Not to just make the pairs equal in balance, in comparison with each other.

It is both, actually. The linchpin for flutter is that the center of lift be aft of the center of gravity of the control surface. I'm also not an engineer, but my feeling is that this requirement is still met.

sonex892 wrote:I am doing some aerobatic training at the moment and was thinking of swapping mine over to aerobatic ailerons.

Shouldn't be terribly difficult... other than making new flaps and ailerons, you'll need to drill out and swap out the piano hinges on the rear wing spars (the flap hinge could conceivably be cut short so as not to drill out the entire hinge, I imagine.) Besides that, I don't believe there's anything else to change in the aircraft.

I'm a bit behind on updating my blog, because I've been working my butt off! I finished my right wing last night.... Which means my empennage, aft fuselage, and wings are DONE!

I'll get the blog caught up soon, but for now I put together a few videos.

Here is a 3600x speed timelapse video of my work over the past 1.5 months, beginning with the right wing spar and finishing with last night's completion of the wings.

http://youtu.be/hfjD3skvHTo

This video is just a narrative summary of my project to date:

http://youtu.be/A_3y1wOwBHM

And here are some photos:

Glad I got the prebuilt spars. Looks like it will save me about a minute and 10 seconds.
Looks good!

Bryan Cotton wrote:Glad I got the prebuilt spars. Looks like it will save me about a minute and 10 seconds.
Looks good!

Hah, thanks! In actuality the spars took me about 80 hours.

Fun times tonight drilling out 116 rivets in and around my fuselage cross tie box to replace bad aluminum kit parts.