I also use a digital fish scale. I have a engine stand with ball bearing slides. The OS web site recommends a 13X9 or 13X10 prop for the .91FX The 13X9 APC revs quick and pulls hard, but does not want to idle slow. I have my .91 on a .60 size Cermark Sukhoi and with the 13X9 it is FAST!!! It also has unlimited vertical and pulls out of a hover with authority. With the 13X9 add the high idle speed with very little prop braking and you end up with some very fast landings. I will try to attach a pic of my engine stand.