Fountain build
 

Good that you are showing Reggie how it should be done.

Very nice work!

Truly amazing commitment!! Your glass work is superb.

Are there any other driveshaft options if (not being negative) needed?

Thanks! No, carbon fiber is only material that strenght to weight ratio is high enough, maybe titanium too but it’s out of budget.
But if I can’t do good enough carbon tube this summer, I think to use temponary aluminium drive shafts but they can not spin full speed.

I strongly recommend that you don’t waste your time with infusion testing, because it won’t be successful. I am convinced that the only way you will produce suitable shafts is by using a high-pressure autoclave and if possible prepreg with a resin system certified for aerospace use.

The laminate must be homogeneous and free of air bubles, while at the same time containing as little resin as possible—and you won’t achieve that without the proposed solution.

In principle, you can make a laminate yourself using a sufficiently high-quality resin. You would produce it by infusion, cover it with a bleeder, and then put the vacuum-bagged part into an autoclave—but this requires a very experienced hand.

For at least the outer 25% layer, I would use UHM fibers.

The highest-quality shaft would be produced from UHM roving, braided over the mandrel in a 3D pattern. You take three or more roving spools and interweave them longitudinally over one another during winding. You can build a very simple tool to perform this interlacing. A laminate like this cannot delaminate—it can only fail structurally. Many dynamically highly loaded products are made this way, for example high-end hunting archery arrows, the most highly stressed mechanical components in expensive cars, and aerospace structures.

I believe you have experts around you, but from my own experience I can tell you that there are very few specialists who truly master what you need here, and they are probably not nearby. In Scandinavia, I would only contact SAAB Aerospace, or possibly Koenigsegg. And remember that in the end, at the final stage, you will be dependent exclusively on your own knowledge and your own understanding of the problem. I had a comparable experience when I needed similarly demanding products. We use dozens of medium-sized fiberglass parts made by vacuum infusion every year, so I thought it would be easy—but within a 1,000 km radius there was no one willing or able to take it on, even though I know people such as the former technical director of Elan Marine, who also mastered sailplane construction. And within this radius, it is likely that most of the major Italian manufacturers of marine vessels and wind turbines are included as well.

Don’t overcomplicate things and don’t look for shortcuts, because you’ll end up giving up. Invest in an autoclave, and if not the first part, then the third or the fifth one will be usable—you’ll know immediately when you take it out of the bag. When it’s right, it will ring like a champagne glass.

Plavutka, I won't need spaceshuttle or Formula one quality carbon part for Fountain drive shafts, they have to transmit torque that is necessary and withstand 4600rpm with out vibration or explode, nothing more nothing less.
Steel or aluminium are fine to 3500rpm and high quality carbon may double that.
Company I bought heavy triaxial carbon fabrics and infusion epoxy make big, meters of diameter tanks end caps by infusion, thicker carbon than my driveshaft and they pass pressure tests etc., my friend company have make big boats and all kind of stuff by carbon and resin infusion. Baltic Nautor Swan sailboats are epoxy infused carbon fiber(made in Finland). You are wrong and right, it's very difficult or impossible to make as good part as prepreg in autoclave by infusion but I don't need that high fiber resin ratio, I'm not hunting 0.001sec of some lap time or try launch vessel to orbit, it doesn't matter are my driveshafts kilo heavier or lighter if they won't break.
Trick to avoid delamination is NOT pulling full vacuum in bag, then there is more room for epoxy and it won't delaminate so easily. I tried it in test pieces.
I will try double bag too, just out of interest, first pull like 200mbar vacuum in inner bag, feed resin, then full vacuum in outer bag, it will squeeze excess resin out without boiling gas in epoxy because epoxy are in athmospheric pressure.
50/50 resin/fiber ratio should give me missing 1100rpm made by triaxial fabric so there is zero degree orientation too that can not be done by winding machine. I really don't need something like 70/30 ratio. Resin rich tube could be benefit if it will be little flexible under torsional force, dampening hits from propellers to CV joints and splitbox
By the way my partners cousin was working for Koeniggseg many years, they do all parts from prepreg to machined aluminium molds. But their company are little more high end than mine....

Ok, noted.
From my experience, there are always some little gremlins that show up and mess with the expected properties, so I simply wrote how to achieve the lightest and most homogeneous structure possible, which is a guarantee of success. If there’s no need to overcomplicate things, even better!

If one drive fails, is it still possible to reach the port only with the other one?

I'm sure you've considered, but isnt there an option of having a 2 part driveshaft with a carrier bearing. You could then fabricate an aluminum driveshaft that is short enough to spin 4600+ rpm?

you can buy carbon drive shafts that will be strong lots of drag racing guys run them there are videos on steve morris engines page its the best way to go

Why not something like this:

They claim 9500 rpm...
https://pstds.com/product/3-75-carbo...cat-driveshaft They are made from rovings with a “3D” interweaving, so delamination is ruled out, cured in an autoclave and with a minimal resin content.

https://pstds.com/critical-speed-chart

If something like this already exists, there’s really no point in reinventing the wheel, because the manufacturing technology involves too many small tricks that you only learn through practice.