I just got word from somebody who finished up their UCD46 that with a 50sx the plane balances at about 5.5" with the battery all the way forward. This is the rearward recommended CG from what I understand (my manual isn't handy so can't double check that figure). This means you can put a heavier motor in this without worrying much about having to add tail weight. With the OS 70 around 20 oz w/muffler that should be ok for balance but would like to hear if anybody has tried one yet.

I'm waiting on some items to finish up my review on this for the magazine...I'll try to finish it up asap with as much detail as I can.