The shortened shroud would be nice sometimes, and maybe even cut all the way back to the stator vanes if you really wanted to save weight, like the GP 30mm fan does. However a quick cut with a razor saw, a sanding block, and the shroud is whatever length you want.
I did a bit of experimenting today with the AH 7mm motor since I had it, and since I did not have Kev's rotor, I made one from aluminum. I also made a tiny prop adaptor to make it all work. I think I can make a second rotor that will be even more efficient but i worked OK for a first try. Most interesting is I did acheive almost the same loading on the motor as I formed the blades on the rotor during the test. Thrust is also almost the same. Pushing over 7.2g after over a minute or two passed on a fresh cell, and 0.6A draw.
This is now a 22mm EDF putting out as almost much as the AH 30mm EDF. Of course this is using the exact same motor and equipment on both tests. Not bad considering that the diameter differance from 30mm down to 22mm is a reduction in area of 47.2%. I calculate that the 30mm has 706.8mm/2 to the 22mm having 380.1mm/2.
I am sure brushless could do more, but at much higher wingloadins as the equipment, batteries, and motors grow in weight. A ligh brushed system is still one of my favorite ways of motivating micro projects. I am eagar to try one of the Flyzone moters when they arrive.
More to come. If Kev wants this posted elsewhere, let me know. More to come