djmp69

Just wondering if a Carbon Fiber wingtube would be ok for a 50cc 3D plane. The ARF normally comes with an aluminum tube. A bigger, heavier aerobatic bird from the same company uses the same diameter tube; it's just longer and carbon fiber. Yes, I've checked the fit. I'm wondering if it would be ok to get the bigger carbon fiber tube and cut it down to size? I plan to put some Gs on the plane, you know, really aggressive aerobtics and 3D. I've heard that CF is really strong, and I know there would be a definite weight advantage, but would it really be a good replacement for the aluminum tube in terms of strength?

Thoughts and/or experience anyone?

castlebravo

I would go for it....if the proposed CF tube was used in a similar airframe you should be good to go. CF has the advantage of being much stronger for the same or lighter weight. You also have the advantage of CF being significantly stiffer....however this can be a disadvantage also.....Aluminum tubes bend when subjected to forces beyond their design strength.....CF tubes tend to break without warning. CF tubes are a little more fragile when handling so if you're in the habit of dropping them....they can be damaged more easilly than Aluminum.....but if you're not using your wingtube as a light sabre....you should be fine! Both of my 40%er's have CF wing tubes.


CB

dbacque

My Feedback: (3)

One note about carbon tubes. I have a 2 meter pattern plane that had carbon wing tubes. One day I noticed a funny line on the tube right at the root rib. I sanded the tube down but the line persisted. It was a crack! Had I not spotted this, I would have eventually lost a wing in flight.

Carbon is great. Just be sure to inspect at stress points regularly. This crack showed up as a line right at the root rib location. Without looking close, I would have missed it.

I say it had carbon tubes because I had aluminum tubes that fit and were free. So I'm currently flying aluminum tubes. I'd switch back if I had free carbon tubes.

Dave

jester_s1

IMHO, the tendency of aluminum to bend rather than break doesn't help. If you bend your wind tube, you'll break the structure that holds the wings on and they'll come off anyway. The whole point of a wing tube is to have it stronger than the flight forces can ever be.

daveopam

My Feedback: (9)

The CF is stronger and lighter. Don't see a down side.

David

Jennifer Curtis

I wouldn't cut the carbon fiber tube.
Its too easy to make unseen weak spots..
I'd make the wing accept it full length.

Jenny

saintcreed

My Feedback: (205)

If it's longer just cut to length, no ill effects by cutting it. Besides at the end of the tube the stress is a lot less. the main stress is at the root. Wrap the tube with tape where make your cut

MTK

First off, I agree with the folks that said go for the carbon tube. The mechanical strength of the carbon is several times that of aircraft grade aluminum, thickness for thickness and size for size.

Make sure you get a tube that has the same length as the original. Reason, the sockets in the wing have internal supports and short changing the supports (also depends on the design of internal support) might cause a failure where the carbon tube ends.

Although the carbon is stronger than the ally, don't sacrifice tube wall thickness. Use about the same as the ally; a little thinner is no problem, just don't go nuts. Example, if the ally wall is about 040 (1 mm), a carbon tube with a wall of 032-035 is fine but don't go down to 020. The weight of the carbon tube will be less than half the weight of the ally and the carbon will be stronger and far stiffer. And no, it won't suddenly break in even the most violent maneuver assuming the plane doesn't weigh a ton. If the ally worked, the carbon will work better

Go to the ACP (aerospace composites) site and look up their carbon tubes. They offer tubes that are wound with cloth on the outside and roving on the inside. No danger of ever developing a hairline crack in this style of tube. That's what I use for all of mine. These guys are very reputable and don't cut corners in their layups.