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Question about Carbon Fiber and Covering

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Old 12-19-2003, 09:49 PM
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DeafOldRocker
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Default Question about Carbon Fiber and Covering

Hi

I am new to the forum and so far it has some really great information, however I have a couple questions that I cant find answer by searching the archived posts.

I am scratch building a plane (the Spitifire from FLYRC mag) and have the fuse assembled along with the tail structure. I am currently working on the wings.

The wing structure is made from two spars along with cap strips below the spars an above to form the curvature normally done by using ribs. Of course there is both a leading and trailing edge to the wing made by laminating balsa strips and sanding to shape.

I want to reinforce both the forward and rear spar with carbon fiber tape. The tape I have is from Hobby Lobby and you use CA or epoxy to glue it to the wood. The fibers all run in one direction along the length of the tape. The tape is 1in by 72 in. I will cut it to the shape of the spar whose profile dimensions run from 3/4 in to approx 1/4 in at the tip.

My Question is : Will applying the tape to the leading edge of each spar be enough to add strength or should both sides of the spars be taped? Weight is a concern.

My next question concerns covering the plane. I will be using Coverlite. I have been told by several people to attach the tail to the fuse and cover as one unit and then cover the wing by its self. Other have said attach everything (tail, wing to fuse) and then cover. I have covered several very small free flight models with tissue(using a mixture of glue and water to attach and the spray water to shrink) this way, however I am concerned that it wont work using a "plastic" covering that need to be ironed on.

Thanks for your help in advance.
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Old 12-19-2003, 11:36 PM
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Default RE: Question about Carbon Fiber and Covering

first, if i follow, you want to wrap the spars in CF tape? yea, that will add a LOT of strength, but remeber that the glue wont seep int othe CF after it dries so your gonan have fun with the ribs, however, epoxy does stick to it so a drop of epoxy would hold it. (My oppinion, your free to disagree all you like)second question, id attatch it then iron, thats how i do it and it works. you just have to be patient and fairly good at covering. if its your first or second time and you are not to the point where you can cover a fuse with few wrinkles then cover it the attatch remembering to cutaway the plastic where glue will be applied (no you cannot CA the covered piece tot he plane, you must remove the covering over the part that touches the fuse). ive never used that type of covering though although if its like monokote and econokote then theres no problem either way.
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Old 12-19-2003, 11:50 PM
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Default RE: Question about Carbon Fiber and Covering

ORIGINAL: Balsa Master

first, if i follow, you want to wrap the spars in CF tape? yea, that will add a LOT of strength, but remeber that the glue wont seep int othe CF after it dries so your gonan have fun with the ribs, however, epoxy does stick to it so a drop of epoxy would hold it. (My oppinion, your free to disagree all you like)second question, id attatch it then iron, thats how i do it and it works. you just have to be patient and fairly good at covering. if its your first or second time and you are not to the point where you can cover a fuse with few wrinkles then cover it the attatch remembering to cutaway the plastic where glue will be applied (no you cannot CA the covered piece tot he plane, you must remove the covering over the part that touches the fuse). ive never used that type of covering though although if its like monokote and econokote then theres no problem either way.
Thank you for your response! No I am not going to wrap the spars and Ribs are not used in the construction. I have added a picture of a completed model (not mine yet) which shows the wing structure.
I was only planning to put the tape on the vertical surface of each spar closest to the LE of the wing. What I was asking was : Is this enough or should both vertical surfaces be covered? I hope this is clearer.

Coverlite is like Monocote it is just extremely light, something like .089 oz sq yard.

Thanks again.
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Old 12-20-2003, 01:56 AM
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Default RE: Question about Carbon Fiber and Covering

Don't know how much strength you'll get from the CF on the vertical surfaces. It's normally applied to the top and bottom of the spar so it acts like a spar cap and the spar acts somewhat like a shear web. If you want it strong you should apply it with epoxy and wrap it with kevlar thread. The thread will help keep the CF from buckling when the spar flexes. Whether you do both sides depends on how much force you expect it to take. Since it's not going to be able to act in tension or compression I'd do front and rear to get all I could out of it.
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Old 12-20-2003, 04:53 AM
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Default RE: Question about Carbon Fiber and Covering

I'm not clear on why you think the design needs to be strengthened?
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Old 12-20-2003, 05:23 AM
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Default RE: Question about Carbon Fiber and Covering

ORIGINAL: CafeenMan

I'm not clear on why you think the design needs to be strengthened?
FYI - The spars are 1/8 in thick balsa with the grain running lengthwise.
This is the first "ribless" wing I am building and thought that it might benefit from some extra strengthing.
Also while I been flying for a year plus, the planes have been mostly ARF or RTF made of foam and carbon rods.
This will be the first electric powered plane I have built (I have done kits for rubber band powerd) and dont want to bust it up to badly if (when) I crash. Landings seem to be harder on my planes then flying since I joined a club with no trees near the field.

BTW - You have a great web site. I have read every page and your tips on building have helped me beyond belief.
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Old 12-20-2003, 05:34 AM
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Default RE: Question about Carbon Fiber and Covering

DeafOldRocker - What band(s) made you deaf??? My personal favorites are BOC, Rush, Neil Young and Floyd. Couldn't even consider having a shop without a good sound system in it.

Thanks for your compliments about my site. I'm glad it's helpful to you.

Personally I wouldn't play around with a design too much unless you know for a fact that it needs to be modified. I was just asking because I see a lot of guys "improving" designs which actually degrades them by adding unnecessary weight. I'll leave this thread to those more qualified than me to talk about CF. I don't use the stuff unless a kit or plan calls for it which has been once the whole time I've been building.

Best of luck with your building,

- Paul
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Old 12-20-2003, 05:50 AM
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Default RE: Question about Carbon Fiber and Covering

Paul
I had a misspent youth going to way to many concerts. Neil Young, BTO, Floyd, Queen, Eagles,
even DEVO along with Frank Zappa are some of my favorites. I work/read/build models best with the music playing, tho these days I have to use head phones so as not to wake my 3 year old. My wife says my hearing is only bad wehn she is talking.

I am not concerned about the design itself, as I have already built the fuse and tail parts and they seem sturdy. I had the CF tape on hand and just thought that the less then 1oz wait gain vs the added strength could not hurt. Also I will be saving some weight by using some micro servers and leaving off the landing gear as the club only has a grass field.

I guess my theroy is if I crash and mess up the wing, the LE can be repaired easier then having to deal with a broken spar and LE.
Matt
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Old 12-20-2003, 09:19 AM
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Default RE: Question about Carbon Fiber and Covering

I agree with Cafeenman. The spar looks plenty strong as is. On electrics, every ounce counts. By the way, still into old 60s folk music, and old rock.
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Old 12-20-2003, 11:30 PM
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Default RE: Question about Carbon Fiber and Covering

ORIGINAL: Flypaper 2

I agree with Cafeenman. The spar looks plenty strong as is. On electrics, every ounce counts. By the way, still into old 60s folk music, and old rock.
After dry fitting the wing parts and pinning everything down, I will have to agree and say the wing will be solid. I think I will skip the CF.

Yes I still like the old bands (God how I hate when kids refer to my music as the oldies! I am only 43) alot of music today is Cr@p.
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Old 12-20-2003, 11:35 PM
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Default RE: Question about Carbon Fiber and Covering

ORIGINAL: DeafOldRocker
alot of music today is Cr@p.
Hey... they may not be able to play an instrument, but the perms are cool! [:'(]

I was playing Blue Oyster Cult one day (Heaven Forbid) and one of my younger friends says, "I hate all these bands that try to imitate Metallica!" LOL. Trying to explain to him that they set the standard before he was born was fruitless.
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Old 12-21-2003, 12:27 AM
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Default RE: Question about Carbon Fiber and Covering

ORIGINAL: CafeenMan

ORIGINAL: DeafOldRocker
alot of music today is Cr@p.
Hey... they may not be able to play an instrument, but the perms are cool! [:'(]

I was playing Blue Oyster Cult one day (Heaven Forbid) and one of my younger friends says, "I hate all these bands that try to imitate Metallica!" LOL. Trying to explain to him that they set the standard before he was born was fruitless.
The worst is these youger bands that cover old music such as Floyd Led Zep or God forbid Maddona remixing American Pie.
Don't get me wrong there is some good music now, just not as much as the "Good Old Days". I also like Toby Keith and some of the other country singer. Like classical too!

You should see the looks I get from the local kids when I drive thru the local park in the summer with the windows down and Ozzy or ZZtop blasting. It gotta be funny to see a guy in his forties and balding driving a big chrysler and blasting rock music.
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Old 12-21-2003, 12:47 AM
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Default RE: Question about Carbon Fiber and Covering

ORIGINAL: DeafOldRocker

ORIGINAL: CafeenMan

ORIGINAL: DeafOldRocker
alot of music today is Cr@p.
Hey... they may not be able to play an instrument, but the perms are cool! [:'(]

I was playing Blue Oyster Cult one day (Heaven Forbid) and one of my younger friends says, "I hate all these bands that try to imitate Metallica!" LOL. Trying to explain to him that they set the standard before he was born was fruitless.
The worst is these youger bands that cover old music such as Floyd Led Zep or God forbid Maddona remixing American Pie.
Don't get me wrong there is some good music now, just not as much as the "Good Old Days". I also like Toby Keith and some of the other country singer. Like classical too!

You should see the looks I get from the local kids when I drive thru the local park in the summer with the windows down and Ozzy or ZZtop blasting. It gotta be funny to see a guy in his forties and balding driving a big chrysler and blasting rock music.
They probably just figure you're a burnt-out biker gone corporate.
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