pyrahna wrote:
In my opinion you are going about your discussion on wheels the wrong way. You are trying to explain why the data isn't good with theory as opposed to trying to explain deficiencies in your data and the way it matches up with theory.
For example if you are interested in bicycle aerodynamics and the study of it in wind tunnels you should preform 2 sets of tests.
Test A) Go out and perform a repeatable chung test of your equipment and position and get a CDA for that setup. Concentrate on repeating that data and minimizing your error window.
Test B) Take that same setup to a wind tunnel and attempt to measure the CDA in the tunnel for that setup.
Do they match? If they do great! A windtunnel is a repeatable instrument to test aerodynamics of a bicycle and it's parts within your margin of error!! You are done, go home have a beer.
Do they not match....shucks....pull out the white board and start doing free body diagrams and equations to see if you can come up w/ the math that makes up the differences. Then once you have come up with that math, derive experiments to prove the phenomenon you have shown to be the difference are actually the difference. Preform those experiments and learn some more. Rinse and Repeat. Spend a career doing this or get your PhD. Spend nights not sleeping due to night terrors about dissertations....when that's all done decide whether you are the type of person that insists on being referred to as "Dr." or not.
Coming up w/ the theory before you have the data is a kind of mental self pleasuring that doesn't really get you anywhere.
The reason why I came up with the discussion of wheels in that thread is that there were dissenting results/opinions of the difference in drag between discs and spoke wheels. Some windtunnel tests had quite small differences and testet a 808 e.g. having the same drag as a disc (this was in a "Tour" windtunneltest a couple of years ago but that is a German magazin). I know of people who posted fieldtests they did, where always a siginificant advantage of a disc compared to a spokewheel resulted. Clearly discs are widely used, also amongst professionals.
And: There are dissenting opinions about the concept of "rotational energy", whether that is measured in a windtunnel or not.
That's how I came to my theoretical interpretation about what happens to a wheel in a windtunnel. Most important is here that part of the rotational energy is measured in a windtunnel by the horizontal scales, part is not.
But this has all nothing to do with the P5.