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addikted2boost
29th October 2011, 09:11 AM
im thinking about making a carbon fiber zephyr style plane out of a single sheet of .05"x24"x60" sheet of carbon fiber. my questions to you guys is do you guys think it will be a good flyer? and do you think .05" is thick enough or should i go thicker? also im looking into maybe learning how to mold carbon biber and if i think i could do it i would try and mold a whole zephyr so that i could put everything inside of it. its just a thought lmk what you guys think or if fiber glass would be just as good.

Dionysos
29th October 2011, 09:21 AM
Hi,
you need to set up some specs first. What is that thing supposed to achieve?
Around those it's much easier to design a plane. At first, there is no problem, but when you start embedding everything neatly, things become difficult. The Zephyr is not the non-plus-ultra-plane.

If you have no idea about carbon or glass fiber build something our of foam or better: wood first, then consider molding. A mold by right, leaves no room for building mistakes.

In terms of calculation, i.e. you must know your flight envelope, the speed that you are flying and the g multiples it has to withstand. Once you know that, you can calculate the torsion and the bending torque on your wing. From there you can see if your carbon sheet will be sufficient. Don't forget to plan for safety factors. Unfortunately composite materials are everything else but easy to calculate. You need to be very specific with what kind of fiber you are using and especially the fiber coating. Then, the big advantage about composite material is the way the fibers are placed, unidirectional or 0/90 or +45/-45 are amongst the most common ones. Then you need to determine your fiber volume ratio and the parameters of the resin. After all that, you get your E-module and Youngs module to start your first strength and durability equations. The last two are one (among other) the biggest problems because you need to feed nastran or patran with those parameters otherwise they are useless. No FEM software will work without those.

All the necessary test make this development process very costly.

Thanks and regards,

Dio

addikted2boost
29th October 2011, 09:41 AM
HOLY CRAP i thought maybe id be able to buy a kit and poor and use it to make a carbon fiber mold or fiberglass mold with and my goal is fpv im going to look around to see if this is at all possible for less than $1000

aaron_gx
29th October 2011, 09:44 AM
carbon fibre blocks rf signals. If the whole plane is made out of carbon fibre, there will be some major null spots in your video and control signals. Fibre glass is a much better choice, as it is far more RF friendly. Just a thought.

addikted2boost
29th October 2011, 09:56 AM
carbon fibre blocks rf signals. If the whole plane is made out of carbon fibre, there will be some major null spots in your video and control signals. Fibre glass is a much better choice, as it is far more RF friendly. Just a thought.

thanks i did not know that imlearning more and more every minute :)

Dionysos
29th October 2011, 10:48 AM
Hi,
not true... you just have to mount the antenna outside the fuselage. Or how can a Boeing 787 operate all the way higher output RF equipment?!?
The problem is electromagnetic compatibility. As carbon is a conductor, however, not a very good one, it may become an antenna at a certain frequency... This is something you must try out and play with.

Carbon fiber is still way stronger than glass, however, it's more brittle.

Interesting though that carbon fiber has a negative expansion coefficient. so to say, you warm it up, it SHRINKS...

That way they can design satellites that are exposed to extreme cold conditions (space) and hot conditions (sun radiation, the side of the sat, that's facing the sun) without warping...

Thanks and regards,

Dio

Edit:
I think you may be able to get the job done with about a 1000$. But that doesn't leave room for experiments and failed trials. If you're a beginner, build one out of balsa and start molding something small. 1000$ doesn't include vacuum pumps or anything that has to do with vacuum technique. for 1000$ you may be able to do some wet-lay-up stuff. If you're from the states, check out Airtech, they have cool a cool catalog with samples, try to get one by ordering it for your company (not private person)...
http://www.airtechonline.com/

aaron_gx
29th October 2011, 11:02 AM
This might be ok for a boeing, which never dives, flies inverted etc... I think even if the antenna was mounted externally, you will see some bad dropouts in your video when the carbon body blocks direct LOS from the video antenna to the ground station, like diving down a mountain, or flying directly overhead. Ideal video transmission should be a perfectly round radiation pattern. If you have a large ground plane (carbon fibre fuselage) directly under the active element, it will change the antenna radiation quite dramatically.

addikted2boost
29th October 2011, 11:25 AM
well hopefully i can find a way to do this project it would be very interesting