50

Well, we're down to 50 days. The flywheel is finally designed.

I cannot count on fingers and toes, the number of times I had to revisit the design to dig deeper and deeper into the calculations. Here are a few words of advice from me if you're attempting to design something for the first time(or first few).

First, breakdown the assembly into elementary parts.
Then, make a list of parts that have to be custom designed/assembled and parts (or sub-assemblies) that are commercially available.
Survey the commercial products first before you begin the design of the custom parts.
Pay particular attention to the dimensions. You must make sure that you know not only the dimensions and strength/desired properties of the parts you need, but also if those dimensions are supported by the commercial off the shelf manufacturers.

For example I was going to choose a X cm diameter shaft but found that while bearing were available for such a dimension, if you wanted mounted bearings (with the housing, making it easy to install), you were out of luck - and for cost reasons, it became apparant to me that I had to redesign the shaft and with it, the method to fasten the flywheel to the shaft as well as the couplings, which then cascaded into further designs. Since couplings with certain combinations of dimensions can be hard to find and expensive, further changes had to be made.

And it goes on and on and on.
Choosing your working range speed is also important because especially for rolling stock, you're going to find your options getting steadily smaller as you look for higher speeds. Misalignments become major issues and machining becomes the determining factor in the quality of the coupling junction. Skimp in a hurry there now and you will be able to regret it at leisure later.

If your speeds call for 30,000 rpm say, you're talking a whole another ball game with magnetic bearings and heavy steel casings to contain flywheel blow outs.

Keep safety factors in mind AT ALL TIMES. Know when your design is most likely to fail, know what safety measures you took to mitigate that eventuality - install safety kill switches.
Test as you go. Dont move past a subassembly unless its tested OK.

One simple, inexpensive but useful trick you can use is as follows, however be warned that you must not be pulling more juice for the entire set up than could be handled safely in a single power strip - because in the end, thats where its all going into and coming from. If the power load you will consume can all be handled safely by a single power strip, you could choose to cascade several power strips (a master power strip controlling the overal power and a power strip per subassembly/important part that you want to power up or down at some specific point/situation) to give the researcher the ability to start up/cut off power to selective subassemblies safely or start up/cut off the power to the entire set up at once. I use that one when I see a minor problem - a loose screw for instance. I shut down the relevant subassembly without closing down the computer interface I regularly use to control the subassembly - it allows me to work safely while at the same time allowing me to power back up and resume without going through laborious countdown checklists.
Once you have a prototype you want to run, you should prepare a countdown checklist - things you have to do in the order in which you have to do them to safely powerup the machine and power down the machine on a regular run.
Make observations diligently and sign and date them.

Things are looking good. Its fun regardless of the end results I obtain from the device regarding the theories I am testing.

Its expensive but it can be fairly affordable IF (and its a pretty big if) this is you make this your main vocation. Because then it becomes a game of installments - of work and pay, work and pay. If time is on your side, no problem.