Isn't it obvious by the results that Km and Km2 aren't all that useful?
i dont see the point. lifeforphysics and you ride about this Km figure. It is not valid to compare motors just by this figure for sure. There is no "one figure" that you can compare every motor to every other one, and this can never exist, as there is no way to pack all 5 valuable aspects into one single figure.
the only way to get it down to two basic figures is: ignoring the rest + only talk about specific figures to merge them with weight. I proposed a way to merge hyst. and eddy torque: Treat them 1:1, which gives you an efficiency number at some "random" (in my eyes a reasonable) rpm. Have you ever looked at the rpm that come out of this 1:1 thing? Most times it is a perfect match with "nominal" rpm. It's the best way i see. This way you get a power figure and an efficiency figure to compare. As you can see, the more expensive designs gain significantly higher figures than the cheap motors, no matter if it is inrunner or outrunner. What more can we ask for?
the only other way i see to get it down to two is: completely ignore eddy current torque. just compare Km and hyst torque. Still not as reasonable as this 1:1 thing IMO. A significant value is left out: The ability to spin fast and get a high power out with reasonable power loss (heat-out). Seems like we have to live with comparing 3 figures or stick to this 1:1 hyst./eddy torque story. Or even compare all 5, as there is weight and heat sinking ability, too. There is no easy way to compare apples and oranges. Both fruit, but the apple never becomes as juicy.
My proposal on a "rank
": Make it specific power at 1:1 eddy/hyst. torque. Efficiency is very high for the top members anyway, otherwise they would not gain such a great specific power figure
Rank1: Nissan Leaf @ 1904W/kg @ 97% @ 7325 rpm @ 178Nm
Rank2: HubMonster @ 1612 W/kg @ 95% @ 1459rpm @ 61.4Nm
Rank3: MidMonster @ 962 W/kg @ 94% 1080 rpm @ 33Nm
Rank4: Joby JM1S @ 624 W/kg @ 92% @ 1621 rpm @ 5Nm
Rank5: Astro 3220 @ 495 W/kg @ 92% @ 9000rpm @ 3Nm
just to give an example, i played around a bit with figures, so they may be off at some point. Still it gives you an example i think
this is very unfair for the old joby though. it is designed so it has quite some eddy current torque, so the 1:1 calced rpm is very low. They lowered eddy current torque significantly for the newer revision ( i heard the use .12mm lams now), so i think these values are not correct. The joby should be rank 2 actually.
sadly we have WAY too many holes to plug! We need many many more motors to compare, more precisely measured no load figures. This only the community can achieve as a whole