Sarsipius

I'm building a Sig Ultimate Fun fly and was wondering if anyone had done a pull pull setup on it and how they did it. Or if anyone knows if it is better to move the rudder and elev servos back to the tail. If you move them back how did you mount them?

TailTwister

My Feedback: (1)

Depending on engine weight, move them back. If you are using a very light two stroke, leave it alone, otherwise move at least one. For my Saito 72, I moved both.

I started by picking the spot to give huge throw to the elevators. I put that one just below the stab. Put the rudder servo just below it. I cut the squareish hole completely through the fuselage where the servos go. I cut two pieces of 1/64 ply the size and shape of the fuselage around the servo area. I cut the same squareish hole in one piece of ply. The un-holed piece goes on the back side. I epoxied the ply pieces down and added 1/4 hardwood rails on top of the holes for servo rails. This allowed me to install HS-225MG servos without sticking out the back. I ran the wires along the side using the plastic clips included as pushrod mounting clips.

For my plane, that put the CG almost centered on the spot noted on the plans. Believe it or not, it was still a touch nose heavy.

Sarsipius

I'm using an OS 51SX. What is the weight of your saito?

TailTwister

My Feedback: (1)

The Saito 72, with a muffler, is a hair shy of 17 ounces.

By the way, for a few extra rpm, I understand that the Tower Hobbies tuned exhaust will fit the OS 50SX. The GMS 47 tuned silencer will too.

Sarsipius

thanks

jmulder

My Feedback: (6)

I have an OS 46 FX on mine and I put the servos where they are suspose to be and it needed no additional weight to balance. It is a great flying plane. The 46 is more power than it will ever need with unlimited vertical. Your 50 should awesome..........John

Sarsipius

Tailtwister, I'm a little unclear...did you mouth the servo's vertically with the top of the servo up and the bottom down or horizontally with the bottom and top of the servos sticking out either side? My os50 is almost 17 oz with muffler so I would like to mount my servos aft I think.

Sarsipius

I meant mount....not mouth

TailTwister

My Feedback: (1)

Mine were one just in front of the other under the stab. I mentioned one on top of the other (servo longways front to back) to you to keep the weight as aft as possible.

They were mounted IN the fuselage on the 1/4 sticks (on the left side). They did not stick out of the back side (engine side) of the fuselage. The HS-225MG was shallow enough that the 1/2 inch fuselage plus the 1/4 inch sticks kept them from poking through. A larger servo would have to poke out of the engine side. I wanted to avoid this to help it stay clean.

Sarsipius

thanks...do you get much oil back there on the engine side?

TailTwister

My Feedback: (1)

When I go out to fly, I routinely fly like half a gallon, so yes. There is oil everywhere. An exhaust diverter will keep 90% of it on the bottom wing and stab, but under the tail gets wet too.