Thanks very much for the replies everyone!

I think I will go with the 9-9 fan.

Good to know that it is good enough to cut the fan blades to get it balanced, would be much more complicated else.



But there is yet one thing I am wondering about, what tip speed should I aim at? As I am building a cruising craft low noise is preferable, which means lower tip speed. What tip speed should be enough for my craft, and still not loose too much thrust and lift performance?