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Lendo

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Feb 6, 2013
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405
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Brisbane
Bradopex, a lot of doubters here, but I'm not one of them, however I would say and I've seen (Mike Patey's Video) it would be cheaper easier and lighter to build in all Carbon. I've been helping someone do just that, build a total CUB Airframe and wings from Carbon and it seems much easier than just the skin he did - I suspect a lot lighter as well. Everything is much easier when you know how, but being an engineer, you should get by. I would ask Mike the weight comparison, if he has done one. I can't remember how many layers of Carbon he did bit it seemed a lot for just a skin, carbon is very stiff and strong, even stiffer with a core, even 1/4". Someone on HBA suggested 3 layers of glass (over a core) are required for impact resistance, but two layers of similar strength CARBON is enough over a core externally because it's so stiff, it resists impacts.
George
 

Lendo

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Feb 6, 2013
Messages
405
Location
Brisbane
P.S. Triax Carbon for the Fuselage and Biax or Triax for the wings Carbon is 40% lighter and 60% stronger than Glass and they say stitched Triax/ Biax is 20% stronger because it's not woven material.
Just workout the comparison between 7715 and 7725 Glass and Carbon, Simple yes!
George
 

rv7charlie

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Joined
Nov 17, 2014
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543
Location
Jackson
I don't think anyone is saying a carbon airframe is a bad idea. I know I'm not saying that. But trying to replace a riveted aluminum skin *that is part of the semi-monocoque structure* with just about any FRP skin *that is attached with fasteners* instead of *being bonded to underlying structure* ...
 
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wanttobuild

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Jun 13, 2015
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652
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kuttawa, ky
Bradsopex, welcome man!
Carbon fiber is king, I have been playing with it!
I deliver to 3M in Decatur, (freon)
A lot happening in the red dirt!
Wouldn't it be nice to find an old aluminum plane and use it for a mold?
Thank you for the link to the videos! A lot of knowledge demonstrated!
You will find a lot of knowledge on this site and a lot of naysayers!!
Ben
 

Bradsopex

Active Member
Joined
Feb 17, 2020
Messages
32
The naysayers are just expressing their opinions, and when it comes down to it, they may be speaking from experience I haven't had yet, so I enjoy the discussions.

I know it's complex, and I know when all is said and done, this will be VERY different from the factory Zenith frame. That's also kind of the point. They designed their frame so any average person can build it, but I have quite a bit more experience than average. I do my own composites, welding, machining, drafting, CFD, and FEA. I also do electronic systems and some programming. It's mostly automotive racing parts which have their own unique problems. I have done work on space systems as well as military aircraft professionally. I know my answers haven't been crazy in depth, but I plan on drafting a few things that may explain better. I'm just a dude that's passionate about trying new things.

I like making stuff, and this is something I have been thinking about. The plan started with a Cub frame (because it's honestly easier to do this), but the more I thought about how cool a full carbon Zenith would be, the more I wanted to do it.
 

Victor Bravo

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Jul 30, 2014
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6,727
Location
KWHP, Los Angeles CA, USA
If you are interested in making this outof carbon, why are you even starting with the Zenith fuselage or wing? The Zenith is slab sided and rather unattractive for a reason... because it is far easier to build that way in aluminum without complex metal forming, rolled skins, hammer-forming, etc.

If you are going to use composite, you can make any shape out of it far more easily, even for a one-off. You can make an off-road bush type airplane that is also very attractive, aerodynamically cleaner, etc. There was already one attempt to make a composite utility plane, the Comp-Air, but they actually managed to make an ugly and unsuccessful aircraft. So ini my opinion it warrants an investigation into why the Comp-Air did or did not work, why it is not attractive, why nobody wanted one, etc. I don't know those answers though.

If you are using carbon, you can make a cantilever wing that is still rugged and nearly as light as aluminum, again benefiting from drag reduction, easier entry/exit, and more attractive.

Perhaps use the Helio Courier as your starting point, and execute something similar to that but using composite?
 

blane.c

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Jun 27, 2015
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3,848
Location
capital district NY
Are you thinking like carbon fiber square tubing glued together and carbon fiber skins glued to each side or carbon fiber on both sides of foam or honeycomb or? Since the components like wing and strut fittings will need hardpoints how is that done?

I was wondering like carbon fiber on each side of foam panels that had "pre-engineered" structural values that could be cut to reasonable shapes and glued to square carbon fiber tubing that also had pre-engineered structural values, it could make building reasonably easy if somewhat "squarish". It is then re-enforcing attachment areas with hard points or the like?
 

Bradsopex

Active Member
Joined
Feb 17, 2020
Messages
32
If you are interested in making this outof carbon, why are you even starting with the Zenith fuselage or wing? The Zenith is slab sided and rather unattractive for a reason... because it is far easier to build that way in aluminum without complex metal forming, rolled skins, hammer-forming, etc.

If you are going to use composite, you can make any shape out of it far more easily, even for a one-off. You can make an off-road bush type airplane that is also very attractive, aerodynamically cleaner, etc. There was already one attempt to make a composite utility plane, the Comp-Air, but they actually managed to make an ugly and unsuccessful aircraft. So ini my opinion it warrants an investigation into why the Comp-Air did or did not work, why it is not attractive, why nobody wanted one, etc. I don't know those answers though.

If you are using carbon, you can make a cantilever wing that is still rugged and nearly as light as aluminum, again benefiting from drag reduction, easier entry/exit, and more attractive.

Perhaps use the Helio Courier as your starting point, and execute something similar to that but using composite?
Honestly? The price. I can buy bits and pieces as needed, and not have to get a whole fuselage that I may end up cutting into and modifying. There are a ton of routes I could go, and it could very well change. I would love to do a from scratch design and build, but I think this way will get me in the air a bit quicker, while still whetting my appetite for doing something different.
 

Bradsopex

Active Member
Joined
Feb 17, 2020
Messages
32
Are you thinking like carbon fiber square tubing glued together and carbon fiber skins glued to each side or carbon fiber on both sides of foam or honeycomb or? Since the components like wing and strut fittings will need hardpoints how is that done?

I was wondering like carbon fiber on each side of foam panels that had "pre-engineered" structural values that could be cut to reasonable shapes and glued to square carbon fiber tubing that also had pre-engineered structural values, it could make building reasonably easy if somewhat "squarish". It is then re-enforcing attachment areas with hard points or the like?
An interesting idea, but when I do carbon parts that have to have structural rigidity, I mold in ribs or bracing. Similar to the underside of your car hood, there is stamped aluminum that provides rigidity where needed. You can do that with carbon fiber and make it one piece, adding strength to the areas you need to address expected stresses.
 

Bradsopex

Active Member
Joined
Feb 17, 2020
Messages
32
Lying, lol...

Well, I know it has a 15hp motor, but trust me, this bad boy can do Mach 5 and has a payload capacity of 1000lbs.
See those pinstripes and lightning bolt painted on the side? That means it goes fast...
You forgot it's VTOL too.
 
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