RE: Phoenix Sukhoi Su-31 - Anybody have an opinion???
As for putting a 61 in the airplane............
It appears that Phoenix builds the airplane with a large lead weight "hidden" in the fuselage just behind and below the firewall. It is a sorry way to make up for heavy wood in the tail or lack of lightening holes in the rear, but it does provide for the means to use a heavier engine than the recommended 46-50 one. Simply pull that lead and most of the weight difference would be taken care of.
Also, since OS has brought out their new OS55AX, there is a new solution for more power for this airplane. The 55AX measures the same as a 46AX in all the critical measurements. It's a 10 minute swapout. Pull the hoses, pull the mounting bolts and you're half done. Everything lines up. I have a Tiger2 that wouldn't hold a knife edge with the 46AX and it does with the 55AX.