MATERIAL BUILDING FLAPS AND AILERONS?

14 posts in this topic

Posted (edited)

My goal is to build separate flaps and ailerons to replace the flaperons.  They will be about 15" chord compared to the 8" flaperons because the aileron portion will only be 6 feet long.  I have some ideas of how to build them and enough material to go one of two ways - either fabric covered, or aluminum covered.  Each type would have benefits and drawbacks.  The fabric covered would certainly be the easier, as Dean showed us with our fabric covered wood ribs for the wings.  The aluminum skin might be stronger, but would have a lot of blind rivets to install, and would have to clean, alodine and paint both inside and outside. 

I could cover them with fiberglass, but that sends shivers since I had to work with fiberglass for about 30 years, and still itch when I think about it.  Carbon fiber sounds good, but I know nothing about using it - The more I think about it, the more I am considering fiberglass / Kevlar, but I have no idea how many layers to use and have to figure the cost.....well?

Perhaps the easiest covering that I would be comfortable applying is thin plywood.  It worked well to extend my leading edges.

I would like to get some opinions about the types of construction before I begin this part of my project this winter.  Anyone is welcome to give their opinion.  One of our members made his Catalina flaperons out of fiberglass, and I would like to hear more from him on his process.   This is the last major part of my building this bird from scratch - after that it is just a matter of covering and putting it together.  EDMO

Edited by EDMO

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Posted

Personally I'd go with wood or aluminum covered in fabric. There have been plenty of heavy aircraft that had all aluminum skins yet used fabric control surfaces. It's easy to build, quick to cover and still more than sturdy enough. In my case I'd likely build from wood but may consider aluminum as well. Just depends on which you're more comfortable building with. There isn't any reason the right wood ribs for it couldn't be glued on to the torque tube like the ribs in the wings. 

I've worked with carbon fiber and fiberglass both. Personally I don't think I'd do that for control surfaces, they end up kind of heavy compared to something covered in fabric. Not to mention it usually takes longer and a lot more money to build that way unless you happen to have a mold and all the "ingredients" laying around already. 

That's my worthless $.02 anyway. Glad to hear you're still building either way you do it. 

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Posted

Thanks for the comeback Kenneth,

Sometime I write so I can see it the next day or week and evaluate my options, and I appreciate the thoughts and opinions of others - I have decided at this time to go with wood ribs and wood or fabric cover -maybe a combination of both.  Now, I just have to wait for my "volunteers" to come and help me move my fuselage to another shed - that's something I can't handle by myself.   I will either set up a router to make the ribs, or find someone who has a CNC machine to make about 36 or 40 of them for me.  I have the tubing and the bearings already, and the hangers are going to the welder soon.  I should be posting some progress photos next year.  EDMO

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Posted

Sounds like you should just set up your router. Other than possible the leading edge of your ailerons I don't see a need to skin them completely. Just extra weight that isn't needed. Not really even sure the leading edge needs the skin either really. Guess it depends on your radius as well.

I do the same thing when I post so I can remember what I was thinking later. That's why I have such crazy detailed build logs for my projects.

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Posted (edited)

Sounds like you should just set up your router. Other than possible the leading edge of your ailerons I don't see a need to skin them completely. Just extra weight that isn't needed. Not really even sure the leading edge needs the skin either really. Guess it depends on your radius as well.

I do the same thing when I post so I can remember what I was thinking later. That's why I have such crazy detailed build logs for my projects.

Yes - going for lighter weight, and hopefully less $$$ and time.  The hangers have to operate thru small slots in the covering, like the later Kitfoxes, so at least there has to be some wood or stronger material than just loose fabric in that area - still thinking about that.   I don't think I have logged any building this year - got to get back to that.   EDMO 

Edited by EDMO

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Posted

EDMO, one factor to work into the design is the shift of the aerodynamic center of the wing cord as the flaperons/ailerons are made longer. That will shift the balance of the aircraft and affect the CG needed for trimmed flight.

Recall how a Cessna tucks nose down as the flaps are extended. That is caused by the fact that a substantial area of the wing has a longer cord when the flaps are extended, so the lift shifts aft and that makes the nose tuck down, and causes you to need to trim the elevator up (stick aft). The aero center of the wing is generally about 25% of the cord, so if you extend the flaperons/ailerons 4 inches longer, the wing lift will shift about 1" aft, and the balanced CG will as well. I'd be glad to help you estimate the affect on trim, as I am sure other members might also,

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Posted (edited)

Nick,  Any calculations you or others want to do on my wings would be appreciated.  Remember too that I extended the leading edge 4", and shortened the trailing edge about 1.5", and brought the flap hangers forward at 70 degrees down instead of the factory 50 degrees.  I would have to go measure the difference in supposed wing chord with the larger flaps and ailerons.   I can reflex the flaps upward a little if needed to trim the plane.  I know how the integrated flaps are considered part of the wing chord, but not too sure how the separate "free-air". flaps and ailerons are figured (flaperons).  I need more aft CG with my Soob engine and nosegear up front.   The added weight of the flaps and ailerons should help bring the CG aft.  I also changed the undercamber ribs to a modified Riblett which eliminated some of the rearward lift (nose-down pressure) of the wings.  This should be a whole different bird than my unmodified old Kitfox 1 with the Soob engine.   EDMO 

Edited by EDMO

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Posted

Ed,

Your ribs would give me an excuse to build the router (vacuum) base for my CNC table.  Once I do that the ribs would not take long to do.

Dave In Western IL

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Posted (edited)

Ed,

Your ribs would give me an excuse to build the router (vacuum) base for my CNC table.  Once I do that the ribs would not take long to do.

Dave In Western IL

Dave,  Your offer is greatly appreciated, as was the cutting of the hangers, but I found a place close to me with a water jet and they don't charge for the computer programming to cut my ribs.  They now have my blueprint and I am waiting for the quote for the 40 ribs to be cut.   I would bet tho, that sooner or later, someone will need some ribs cut.  

Added:  I decided to not use capstrips on the ribs, and to ribstitch the flaps and ailerons like the old planemakers did.   EDMO

Edited by EDMO

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Posted (edited)

Final update - Got wood ribs cut on waterjet machine - turned out real precision fit on pivot and leading edge tubes - bought Avid wing leading edge Fiberglass 24' x 15" wide for covering flaps - slots have to be marked and cut after hinges are assembled to wing before gluing fiberglass to ribs.  Guess if I don't get more, the ailerons will get covered with fabric/1mm plywood.  EDMO

Edited by EDMO
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Posted

glad you posted this.  I had not thought about cutting out the wood ribs on the waterjet.  I now have a new mission!  I just got access to a waterjet table a couple miles from the house so I will be cutting out lots of parts.

First job is a new fab / jig table I am picking up all the metal for Wednesday that has been cut and made into a "kit" for me.  Just clamp stuff together and weld!  Mading a sweet jig for wing ribs will be stupid easy cutting them out with the water jet.  Thanks for the idea mr!

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Posted (edited)

glad you posted this.  I had not thought about cutting out the wood ribs on the waterjet.  I now have a new mission!  I just got access to a waterjet table a couple miles from the house so I will be cutting out lots of parts.

First job is a new fab / jig table I am picking up all the metal for Wednesday that has been cut and made into a "kit" for me.  Just clamp stuff together and weld!  Mading a sweet jig for wing ribs will be stupid easy cutting them out with the water jet.  Thanks for the idea mr!

Maybe only difference is that mine were cut really fast with a computer - Sooo Precision!  All I did was draw a pattern and they copied it to computer.  You can do it manually tho.  Good Show!  I forget the exact cost, but think it was $2 each with my material (same as wing ribs) for 40+ ribs - cost was mostly programming for 2 different size pivot tube holes precisely sized and aligned for flaps & ailerons.  Are you still going with Kitfox 4 rib pattern?   I still have some.  Guess larger flaperons could also be made using ribs too and maybe covering with Wood / FG / Fabric / Metal?  

False ribs too.   EDMO

Edited by EDMO

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Posted (edited)

I have a good pattern for the KF ribs now.  I don't have designing costs as I do all the drafting, they just pop the thumb drive in the machine, set a few parameters and they are cutting in a couple minutes.  Yes it is fun watching CNC machines work.  next on the tool list is a decent mill.  Then I should have everything covered for making anything I need to make.

 

I am still toying with the idea of cub ribs on the coyote.  Doesn't seem to matter what everyone else has tried to come up with, cubs still take home the prizes for short field work.  I am not worried about cruise speeds, just turning the Coyote into the best STOL machine it can be.

:BC:

 

Edited by akflyer

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Posted (edited)

I have a good pattern for the KF ribs now.  I don't have designing costs as I do all the drafting, they just pop the thumb drive in the machine, set a few parameters and they are cutting in a couple minutes.  Yes it is fun watching CNC machines work.  next on the tool list is a decent mill.  Then I should have everything covered for making anything I need to make.

 

I am still toying with the idea of cub ribs on the coyote.  Doesn't seem to matter what everyone else has tried to come up with, cubs still take home the prizes for short field work.  I am not worried about cruise speeds, just turning the Coyote into the best STOL machine it can be.

:BC:

 

Guess you could scale the Cub ribs down to match the Coyote spar attachments, or move the attachments farther apart to take larger wing chords?  Might be as simple and easy - just putting in spar holes to match Coyote to use larger chord Cub ribs? ???    I sure like thinking "Outside the box!"  Ha!  I think my extended  4"leading edge modified Kitfox 4 type wings with 15" flaps and ailerons are getting closer to Cub chords.  EDMO

Edited by EDMO
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