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On the side, I'm building experimental composite frames for quadrotors. If I come up with something usable, I plan on selling them to the quadrotor FPV communi

On the side, I'm building experimental composite frames for quadrotors. If I come up with something usable, I plan on selling them to the quadrotor FPV community. Not really a startup, but hopefully a profitable side business. Most high performance quadrotor frames are made out of carbon fiber. This makes them expensive, brittle, prone to horrible vibrations and not so great for RF interference. I'm basically tooling around in my garage with new combinations of composites to see if I can replace CF with something else. =) I'm ex-biology and a year ago worked in a wet-bench neuroscience lab.

niels 14y ago
Sounds cool. Fellow FPV'er here. I think this hobby will explode in popularity really soon, if that isn't already happening.
- polyfractal 14y ago
  Agreed. Components are just getting cheaper and cheaper. The biggest obstacle right now is information and experience, in my opinion. All the good information is locked up in billion-page forum posts. I've considered writing a bunch of in-depth tutorials and info-guides...but just haven't found the time. Experience...well, you just have to crash a few times because the servo is installed backwards before you really understand =)
  - __--__ 14y ago
    What's your take on batteries? I've heard a lot about hobby RC LiPo batteries turning into flaming fireballs due to both improper charging or over-draining.
    - polyfractal 14y ago
      Hehe...yeah... They are mostly safe, you just have to treat them nicely. Improper charging is the biggest risk, so as long as you charge slowly with a proper balance charger there is basically zero risk. It takes longer, sure, but I'd rather charge at 2C and not burn my house down than charge at 10C and play LiPo roulette. I charge and store my batteries in a flame-proof LiPo bag, and will be getting a fireproof safebox soon. A lot of people will fast-charge when they are outside charging from a car battery or something, so it's less of a big deal if it explodes (since you should be charging it on a concrete block or something away from people). Over-draining isn't really a problem, since even cheap ESCs have over-drain protection and won't let you drain the battery. I don't think explosions are a problem when you over-drain anyway...you just permanently damage the battery. Otherwise, the only thing you really have to worry about are crashes. After a good crash, check your batteries to make sure they are uninjured. If they look a little deformed, best to play it safe and store them somewhere safe (bucket of sand, metal box, etc) for a few days to see if they get puffy. Puffy == dangerous, discharge safely and dispose.
cfontes 14y ago
Nice project... I am also an ex-biologist and 4 years ago was working with Sugar Cane genetic engineering and Bioinformatics, it's sad that here in Brazil they pay you s* to research like that and a lot to program in Java. So here I am.
- polyfractal 14y ago
  Haha yeah, that's why my dayjob is as a software engineer. I feel your pain
- just_testing 14y ago
  You were working in EMBRAPA? (I ran away from there because of the shitty payment) ((Nowadays I work in finance...))
shiftpgdn 14y ago
Have you done more research into CF layup? A lot of the characteristics of carbon fiber and defined by the weave of the cloth and layup of the module. The problem with quadrotors are that they're effectively 4 tubes on CF bolted together. A single module system with proper dampening would probably be perfect. For example go ride a really cheap carbon fiber bicycle where they just stick carbon fabric into a mold and then go ride one of the really high end ones where a lot of engineering has gone into the layup and construction.
- polyfractal 14y ago
  I haven't, but mainly because I don't have the necessary space/facilities to work with CF. I live in an apartment and don't really have space to make a CF-safe work zone (somewhere to contain the dust, keep my dog from eating the epoxy, etc). Ditto to a proper vacuum bagging setup [1]. I agree that CF is probably the ideal composite. I'm working mostly with wet-layup fiberglass cloth and sandwich panel constructions, as well as some semi-silly experiments with glue/paper/fiberglass. Also exploring some designs that use tension cables to support the load. Lots of fun, if not entirely fruitful so far [1] I could probably find space for a vacuum bagging setup...but my girlfriend barely tolerates all the stuff as it is. Best not to push my luck :)
mchannon 14y ago
CF is wonderful in compression but leaves a bit to be desired in tension- an ideal composite in your situation will need to support both (and hence their inbred children, shear, torsion, and bending). Kevlar-49 (aramid) and Spectra (UHMW polyethylene) make great complements to carbon fiber. Wrapping your CF with Kevlar fabric (particularly Kevlar prepreg) will help arrest delamination and make the finished composite a lot tougher. Since Kevlar doesn't conduct electricity (graphite does anisotropically), this may help with your RF issues as well.

niels 14y ago

Sounds cool. Fellow FPV'er here. I think this hobby will explode in popularity really soon, if that isn't already happening.

polyfractal 14y ago
Agreed. Components are just getting cheaper and cheaper. The biggest obstacle right now is information and experience, in my opinion. All the good information is locked up in billion-page forum posts. I've considered writing a bunch of in-depth tutorials and info-guides...but just haven't found the time. Experience...well, you just have to crash a few times because the servo is installed backwards before you really understand =)
- __--__ 14y ago
  What's your take on batteries? I've heard a lot about hobby RC LiPo batteries turning into flaming fireballs due to both improper charging or over-draining.
  - polyfractal 14y ago
    Hehe...yeah... They are mostly safe, you just have to treat them nicely. Improper charging is the biggest risk, so as long as you charge slowly with a proper balance charger there is basically zero risk. It takes longer, sure, but I'd rather charge at 2C and not burn my house down than charge at 10C and play LiPo roulette. I charge and store my batteries in a flame-proof LiPo bag, and will be getting a fireproof safebox soon. A lot of people will fast-charge when they are outside charging from a car battery or something, so it's less of a big deal if it explodes (since you should be charging it on a concrete block or something away from people). Over-draining isn't really a problem, since even cheap ESCs have over-drain protection and won't let you drain the battery. I don't think explosions are a problem when you over-drain anyway...you just permanently damage the battery. Otherwise, the only thing you really have to worry about are crashes. After a good crash, check your batteries to make sure they are uninjured. If they look a little deformed, best to play it safe and store them somewhere safe (bucket of sand, metal box, etc) for a few days to see if they get puffy. Puffy == dangerous, discharge safely and dispose.

cfontes 14y ago

Nice project... I am also an ex-biologist and 4 years ago was working with Sugar Cane genetic engineering and Bioinformatics, it's sad that here in Brazil they pay you s* to research like that and a lot to program in Java. So here I am.

polyfractal 14y ago
Haha yeah, that's why my dayjob is as a software engineer. I feel your pain
just_testing 14y ago
You were working in EMBRAPA? (I ran away from there because of the shitty payment) ((Nowadays I work in finance...))

shiftpgdn 14y ago

Have you done more research into CF layup? A lot of the characteristics of carbon fiber and defined by the weave of the cloth and layup of the module. The problem with quadrotors are that they're effectively 4 tubes on CF bolted together. A single module system with proper dampening would probably be perfect. For example go ride a really cheap carbon fiber bicycle where they just stick carbon fabric into a mold and then go ride one of the really high end ones where a lot of engineering has gone into the layup and construction.

polyfractal 14y ago
I haven't, but mainly because I don't have the necessary space/facilities to work with CF. I live in an apartment and don't really have space to make a CF-safe work zone (somewhere to contain the dust, keep my dog from eating the epoxy, etc). Ditto to a proper vacuum bagging setup [1]. I agree that CF is probably the ideal composite. I'm working mostly with wet-layup fiberglass cloth and sandwich panel constructions, as well as some semi-silly experiments with glue/paper/fiberglass. Also exploring some designs that use tension cables to support the load. Lots of fun, if not entirely fruitful so far [1] I could probably find space for a vacuum bagging setup...but my girlfriend barely tolerates all the stuff as it is. Best not to push my luck :)

mchannon 14y ago

CF is wonderful in compression but leaves a bit to be desired in tension- an ideal composite in your situation will need to support both (and hence their inbred children, shear, torsion, and bending). Kevlar-49 (aramid) and Spectra (UHMW polyethylene) make great complements to carbon fiber. Wrapping your CF with Kevlar fabric (particularly Kevlar prepreg) will help arrest delamination and make the finished composite a lot tougher. Since Kevlar doesn't conduct electricity (graphite does anisotropically), this may help with your RF issues as well.