Carbon Fibre (Fiber) Investment

Rick,

For the solar car, we'd source high-grade carbon from anywhere we could get it. On the last car we used some E-761 prepreg material from Nelcote (Park Electro, http://www.parkelectro.com/parkelectro/nelcote_about.asp ) that was among the nicest prepregs I've ever used- easy to handle, draped nicely, didn't go tacky in the shop, cured with almost no pinholes. In dry fabrics, Barrday http://www.barrday.com/ is one of my favourite sources for everything exotic- if you want a laminate of spectra, carbon and vectran with a quartz finish layer, they'll get you the fibres in any pattern imaginable.

Everyone's favourite cell supplier right now is Sunpower out of California, http://www.sunpowercorp.com/ Their A300 cell has just about the best combination of cost and efficiency you can get in silicon right now, and with SunKat encapsulation they're damned hard to break. Emcore and Spectrolab are preferred for those with a few hundred grand or more to drop on cells; those with that kind of money get the encapsulation done by Gochermann.

My team raced Australia in '07, I couldn't go unfortunately.

V-bird,

You're right about nanotubes. The cheapest low-grade ones start at around a quarter-million bucks a tonne for the raw tubes, in lengths of a couple of microns, tops. If you want to process them into anything useful, try an order of magnitude higher.

Potential hazardous effects are, at this point, completely unknown. Various labs are trying to ascertain the health impacts, but to date, no clear data. I'd be happy to discuss this further if anyone's interested.

You're also right that carbon shouldn't be nearly so expensive as it is. Right now the production capacity is very limited and the material is in very high demand. There are only a handful of corporations that control the facilities needed to make it reliably, and they have expressed little interest in increasing supply any more than is necessary to ensure steady (but pricey) supplies to the big clients (Boeing & friends). As soon as the Dreamliner started getting orders, stockpiles dove and the stuff became almost impossible to get, anywhere. Share prices of these suppliers have almost nothing to do with how they're actually doing- the market panic affects all, even those companies that still have more demand than supply.

 

Matt
What is the SunKat encapsulation. There is no reference to it on the Sunpower site that I can find. I am interested to know if this results in a lighter panel than their standard encapsulation.

Rick W

 

Sorry about the typo... it's SunCat Solar that does the encapsulation. Separate company from SunPower, although they have an agreement to distribute custom SunPower panels via SunCat.
I don't think they have a website. They're a specialty supplier that mainly does one-off applications for aerospace, research, and experimental cars/boats. The encapsulation they use laminates the silicon wafers between a reinforced backing and a protective, low-reflectivity top sheet, the whole thing is only a couple of millimetres thick and can actually conform to gentle curves. It's an expensive encapsulation, but it renders the cells almost indestructible (except for hailstorms and sharp impacts) and weighs nearly nothing. The only better one I know of is Gochermann, http://www.gochermann.com/ at about five times the cost.

Last I checked, SunCat are based at:
Address: 17626 North 33rd Place, Phoenix, Arizona USA 85032
Telephone: (602) 404-4929
FAX: (602) 404-4929

Orders of significant size often have a very long lead time. The cost of a small order of fully encapsulated A300s will likely be around $15,000 per kilowatt, give or take four grand.

 

Zoltek

Hi Rick,
Have you run across this company in your searches, Zoltek.

I invested a considerable sum in this company quite a number of years ago as it appeared as though they had an interesting and somewhat different approach to the precurser technologies and being able to 'mass produce' a carbon fiber product at less of a cost....an economy version.

At the time there was a great expectation that the carbon fiber market would grow very significantly. However the real growth area at that time turned out to be in the really hi-end strength fibers, not the mid and lower range fibers of Zoltek. And this combined with a few hic-cups with their foreign acquisition (Poland I believe) for precurser had me sell off my shares.

Of course this was all before we went to war and started using even a greater amount of carbon-fiber materials by military, and aircraft, and etc. I've not looked back at the company in a long time.

But your recent comments about a light weight vehicle fit right in with two subjects I've reconsidered recently:

1) Alternative Powered Vehicles, 3-wheel versions
http://www.yachtforums.com/forums/yachtforums-yacht-club/10458-alternative-powered-vehicles-3-wheel-versions.html

2) A superlight speciality RIB tender

There are quite a few videos referenced in the vehicles I site above. Might be fun to build a combination T-Rex/ FuelVapor/ Aptera unit in low-tech carbon fiber. .....that might be a fun project for Thailand :idea:

 

I got a quote for 3000 a roll a while back
100 ft 50" wide for the tweed I think
it was a year or so ago and it came in after the crash so I didnt give it much attention
I wanted it for my mast and spars but never sent for it
B

 

Boston,

You should look into building your mast out of braid and uni carbon sleeve made by these guys.

Building your own mast is a BIG DEAL, not trivial AT ALL. After you get the engineering done, you then have to design and engineer a construction method to make sure your finished goods are in the ballpark of the engineering predictions.

Several prominent companies making masts at the time I built mine were having failures one after another. These were companies with big professional engineering staff and highly experienced fabricators, so this is not an easy task.

I actually still have a bit of uni and braid left after building the two 45' tapered tip rotating wing masts; enough to build a mast of about 30' with a nominal CS of about 4" dia and maybe a ~.150-.165 wall.

Back when I did this business, I was paying $20 a pound for normal stock woven goods and about $36/pound for the braided goods. Those were the days, huh

PM me if you want to know more. I can even show you the boat on the web; as far as I know the mast is still up and sailing now 7 years later, and on a fairly high performance catamaran, no less.

Jimbo

 

at the time I was thinkin reverse autoclave within a temp controlled oven like enclosure
I used to go the the reno air races a lot



they had this guy won the single engine unlimited class every year
he built his hole plane out of CF but didnt recoment the tweed for anything with a tight bend in it
not sure he used it at all in the plane
something about fiber stress if I remember
recommended the regular standard weave
he's real talkative and Ive got his web address round here somewhere
he walked me though his hole process
looked pretty simple but then again I never tried it
I can see that there would be a learning curve and a few test sections down the drain
so any ideas on the subject are bound to help
although as I said
Im not in a position to do much at the moment

 

Brian
Zoltek looks a good option for those in the US. It is currently trading at USD8.20. Will be interesting to watch over the next couple of years.

I find it a pain to direct invest in US shares because of all the paperwork involved so I will not be following my prediction but I would not be surprised to see this one triple in the next 18 months.

Rick W.

 

Matt
Would it be possible to walk barefooted (very rarely) on the Suncat encapsulation if it was mounted on a rigid but slightly curved cabin top.

I am trying to guage the scuff resistance of the surface.

Rick W

 

We all know that carbon fiber materials will find a greater and greater market, but trying to bet on any particular manufacturer, and especially in this economy, is a bit tricky I believe. Cash flows and management decisions can bring down even good companies. And this economy can bring down good companies that have made good decisions in the past. Hell of a mess

 

We should probably split the solar cell chat into a different thread.

I wouldn't advise walking on any thin-laminate panels, not with current technology. The lamination will survive just fine, it's darned hard to damage, even if you bend a laminate of supposedly rigid cells. The problem is that in the top ten or fifteen microns of the cell itself, you have a thin film electrode and a very carefully prepared P-N junction, and concentrated pressure will squish the electrode into the doped layer, shorting it to the silicon substrate. No amount of protective encapsulation can prevent that, unless the encapsulation itself is strong enough to support the load- say, 3/8" tempered glass.
Solar cars can handle the rain. And arrays get bumped, drivers hit them when jumping clear of the escape hatch. But a hailstorm- concentrated, intense loads, even though the particles are light- drives everyone into trailers. Even if the encapsulation survives, the risk of damage to the cells remains.

 

what do you think of carbon fibre for masts and booms and such

 

Rob denney says he makes free standing carbon masts cheaper than alu masts with stays. He makes strips in molds, from carbon tow, gluing them together afterwards. He is using a home made wetout machine.

Can you use glass fiber as a cover for the solar cells, or is it not transpartent enough?

 

Bamboo fiber as apposed to glass or carbon anyone
was briefly discussed on another thread what do you folks think

 

CF is the future

I worked with this extensively in the Marines working on CH-53E helicopters. The strength of this material by weight is insane, as you have discovered. At roughly $8 (this price has been pointed out to me as unsubstantiated) a pound it is a little expensive......unless you can cut costs on fabrication and assembly. Control your resin content and use pressure molding to make parts in large batches. Like modified hydroform with a heated vacuum cycle. Use as few parts as possible. Spars, Ribs, and runners should be formed as a singular component with the skin directly in the mold. If you would like a good example of this check the Rocky Mountain Institute. Here is a PDF brief that basically confirms everything you imagined in spirit. Unfortunately they do not give much insight on methodology beyond these basic concepts. Imagine a car that is completely undamaged by 35mph impacts - 100mph passenger crash protection - and so much lighter that the current prototype (small SUV) uses as much energy at 55mph as the average large truck A/C. That is with a traditional drive line. Not hybrid or electric but internal combustion gas with a transaxle.

http://www.rmi.org/images/PDFs/Transportation/T01-22_NextExit.pdf

This is for cars but in many ways a boat would be easier to fabricate in 4 - 5 major sections. Outer Hull - Inner Hull - bulkheads and amenities - top deck. Mast? The first exterior seem does not occur until the joining of the hulls and top deck and that is resin sealed. The air trapped between the hulls would give you permanent buoyancy. You could even use puncture resistant spray on PVC liners in the hull. This way if you manage to crack through the fiberglass your hulls are still water tight. If you still sink you probably are not around to care and most likely ran into a sea cliff or a panamax.