I am building the VectorFlight Edge 540 (an awesome ARF) and am going to mount a SATO 91 on it. My question is how far should the front thrust washer be from the firewall? It looks like 5.25" is good but those of you with experience might point out a different distance because of balance or some other reason. I wouold be glad to hear from those of you who have completed this aircraft and any suggestion you might have. I have already change the tailwheel assemble to a much heaver one than the one supplied. John

5 inches in the exact distance for any motor, due to the cowl. It's not really based on balance, as the battery and such will easily keep it on target. I have a Saito 120 mounted in mine and it balances perfectly with 1 oz. lead just behinf the tailwheel. The 91 will nto need extra weight. As my battery is as far back as it can go in the tail, yours will be much closer to the actual servo compartment. I am anxious to hear how the smaller 91 performs. Keep us posted [8D]

you can adjust the engine slightly for balance,but the cowl needs to be set the right distance from the prop washer that is the most important thing.i used a os91fx and still had to add 1 ounce to the tale,i have my balence set 1/2 inch father back than what is called for it hovers pretty good with the balance set like that.i even put my battery's on the firewall just past the servo tray aft,they are 5cell 6volt.
hope this helps some

I have a Saito .91 on my VF Edge.... I mounted mine inverted, and I think I'm a little low (fuel tank to high).... 5.25 is on target... I have a 6v nicad just in front of the wing joiner... Remember to mount the throttle servo in front of the wing joiner.... It's a little crowded in that area, but I have had ZERO problems.... It's a great flying model... and pretty tough. I can hover (slow pullout), and torque roll mine.... Saito .91 with a APC 15x4w