Building New Ailerons

[Ghost]

The time has come to build my new ailerons. I had one destroyed in a hanger accident, and it’s my understanding I would be better off building a matched pair.

 

I’ve done a bit of homework on this topic, and my research has yielded the following findings:

 

1) The VariEZe ailerons are somewhat tricky to balance, trailing edge often below waterline.

2) They are often times built heavy, do to extra weight added to leading edge to balance them.

3) I haven’t been able to identify a “Max Weight.” Which is interesting because how would someone come to the conclusion that they were heavy?

4) Travel should be 20° UP, and 22° DOWN.

 

Taking these notes into considerations, I have opted to build the ailerons out of Carbon Fiber. While the cost is unquestionably higher, the light weight should make balancing a snap.

 

Note: That was a joke of course; nothing in aviation is a snap.

 

The really good news is that I have a friend here in Fla. with a CNC foam cutter that is going to cut the cores for me. I was going to go with Eureka, be I know he is very busy.

 

With a little luck, I will shoot a short video of the process.

 

Any input, and or tips would be greatly appreciated.

 

Ghost

VariEZe N297TV

Miami, Fla.

[TMann]

All of my control surfaces will be Carbon Fiber.

 

Remember to insulate any aluminum with a layer of fiberglass.

Aluminum in contact with Carbon Fiber will oxidize.

[Wayne Hicks]

What type of carbon fiber are you planning to use? 4 oz.? 6 oz.? 8 oz.?

 

Unless your carbon is lighter than the RAF cloth it is replacing, you will save no weight. And if you're not used to working with carbon, your ailerons may end up weighing even more. Since carbon is very black, it is hard to tell when the carbon is wetted out (saturated). This causes some folk to leave too much epoxy in the weave. Also, carbon is not transparent. Some of the RAF insepction criteria can't be used because you can't see through it to the foam.

 

And as already mentioned, there will be galvanic reactions between the carbon and the aluminum backing plate that gets glassed into the aileron. (I'm assuming the VariEze ailerons and Cozy ailerons are built similarly. I could be mistaken.)

[Hercpilot]

CP20 page 5 has some aileron weight info for the varieze! It is not specific as to whether it is a limit or for reference only.

 

Justin

[Hercpilot]

I don't see anything about a balance angle either. Let me know if you find something. I am in the process of weighing and balance checking my flight controls!

[MacGyver]

Carbon fiber - nice for some apps, but no real benefit strength-to-weight if using our hand lay-up techniques (i.e. no better than S-glass, for example).

 

If using it (and I have made Long-EZ ailerons with carbon, as that is what the builder of the airplane wanted), the wetting-out takes patience and close examination (easy to get too wet), and, the need for a glass barrier ply between any aluminum and carbon is absolutely required. You also have to remember to not use the aluminum "pop" type rivets as specified in the plans either, as they mingle with the carbon. Monel pull-type rivets offer the best material compatibility. Then, you have a harder rivet through relatively softer materials, and you have to be careful if drilling them out (like when you have to replace a hinge).

 

Me? I'd stick with the per-plans construction, do your best workmanship, and sand them as Rutan recommends. Then, once painted, re-check for balance.

 

My ailerons required additional balance weight (about 4 ounces per aileron). I've built 4 VariEze ailerons, and yes, I do build light (VariEze #2 is 617 pounds empty, with goodies & tools, etc.). To balance my ailerons, I simply drilled a 1/4 inch hole in each end of the aileron, immediately aft of the steel rod, and used 1/4 inch diameter lead (you can buy 1-pound spools of this at fishing stores) potted in with epoxy. Simple.

 

I have flutter-tested my airplane to 225 knots or so, with control system jabs/sweeps, with no problems. The ailerons are much more tolerant of weight increase than the elevators, FWIW.

 

-Joe Person

VariEze N79JN

Bothell, WA (KPAE)

[Limo EZ]

I could not find a max weight for ailerons in the Long EZ plans and the ones that I cut out of the wings would be out of balance when they were painted. I built a new set out of carbon fiber, vacuum bagged. A lot lighter.

 

Joe

[Steve Innova]

What type of carbon fiber are you planning to use? 4 oz.? 6 oz.? 8 oz.? Unless your carbon is lighter than the RAF cloth it is replacing, you will save no weight. And if you're not used to working with carbon, your ailerons may end up weighing even more.

 

True. The CF UNI (Hexcel 716) on AC Spruce is still 4.7 oz, only a 2.3 oz weight saving over 7 oz fiberglass UNI (you'll use the same weight epoxy), plus you have to add a ply of fiberglass (BID?) to cover the AL parts. Not worth it, in my opinion.

 

Since carbon is very black, it is hard to tell when the carbon is wetted out (saturated). This causes some folk to leave too much epoxy in the weave.

I've used 5.8 oz Hexcel 282 (Carbon Fiber BID) and 4.7 oz Hexcel 716 (Carbon UNI) and have had no problems wetting out the plys.

 

While it's true that CF isn't translucent like fiberglass when wet, with these styles of CF, it's pretty apparent when it's wetted out. You can see the sheen change as the epoxy soaks through. One technique is to apply the epoxy to the object surface, then lay down the carbon fiber ply, and use a hairdryer & squeegee until the epoxy soaks up through the ply. Then you're sure the CF is thoroughly wetted out.

 

I generally brush on extra epoxy when working with CF, and then use a vacuum bag to remove any excess. I can't speak for any other styles of CF, other than the long tape, which I don't recommend -- very hard to wett out.

[Drew Swenson]

CP 21 pg 5 further talks about elevator balance for a varieze (3.9 left and 3.6 right (max) when balanced)