• Troy Newman's Elevator Setup
  
  
• Engines used @ 2001 F3A WC
  
  
• Futaba new FF9
  
  
• Various YS 140 Engine Mounts
  
  
• YS 140 DZ
  

• Introduction
• Cable, Pull-Pull Analysis
• MK BellCrank Analysis
• Alternative Method - Troy's favoured approach
• Initial Setup
• Servo and Elevator Connections
• Servo Choices - JR

My Preferred Method
Now the long awaited method I use. This came to me from Scott Anderson of Dynamic Aircraft. Scott is a master builder and has built championship level airplanes for many of the top guys. Scott also builds TOC aircraft. His work is among the best that I have ever seen. The work is light, strong, and detailed. From what I understand Scott got the idea from a long time pattern flyer Tony Frakowiak. So I want to give as much credit for this idea away. It works great. This method requires much more work to install than the MK or the cables. And it takes doing it at least once to learn the technique of installing it in the fuse. But the second time its cake and you need only line up your servo and your exit holes. The pushrod setup then spans the gap. The extra work is intimidating and can make you stare at it for hours thinking about how it is suppose to work. But when done it is lighter than the MK. Only 2ozs, and its stiffer in the differential category too. Totally mechanical, and if installed properly is friction free. I have some pictures below that show it completed….So you should not have that much head scratching

Initial Setup
First of all the basic layout is (2) solid Carbon Fiber rods running the length of the fuse to each elevator. These are solid rods not hollow….They are 0.070” diameter or the same size as a 2-56 pushrod. So they are pretty small. These rods are available from CST Composites Part #T1070. They are under pushrod kits. They come with a Teflon sleeve similar to a Nyrod housing. Cost is about $8 each and you need two of them. They also come with connectors and fittings to be epoxied on the ends. The bonus is they are 48” long. This makes for a perfect pushrod setup for 2m birds with extra material to spare. They are pretty stiff but will flex and can’t be run unsupported. They are supported the entire length of their travel inside the fuse. Using the Teflon guides they are attached to a light light ¼” sq balsa stick. This can be the lightest you can find because it will become very stiff when assembled in the structure. Don’t just pick a piece of bass or maple that says its balsa.

Ok getting started, you wrap sewing thread around the balsa stick and the Teflon housing with the CF pushrod inside of it. Now don’t warp it too tight as the Teflon will pinch the rod inside and cause more friction. So your goal is to get the Teflon housing attached to the balsa stick. Do this for each pushrod. The wrap is done like a fishing pole with close together wraps for about an inch or 2 then looser for 2-3 inches then tighter wraps then looser. All the time, keeping just enough tension in the thread to keep the Pushrod attached to the balsa stick, and no more. Once this is done you hit the sewing thread with thin CA glue. The balsa will soak it up like mad and will stiffen. This is why a softer piece of balsa will work. You don’t need to get all of it just make sure that the thread and the pushrod are not moving on the balsa stick and there is no way for it to come off. These sticks don’t move and are glued into the fuse as the guides for the CF rods inside the tubes.

Now this is where I vary from the designer’s idea a little bit. I measure the length required to build a ladder from the front mounted Elevator servo to the exit holes in the fuse. I build a ladder type structure attaching the pushrod assemblies to each other. This is done in a big “V” with the Teflon housings on the outside of the “V”. See the attached picture #1 of the inside.

Picture#1(right) shows the ladder built and glued inside the fuselage. The horizontal Balsa former above the ladder is part of the stab install. You should have your stab installed already before you install this pushrod setup. I leave the tail post open so I can get in there and work. But the Stab is 100% installed. I use removable stabs but glued in solid stabs are fine also…The pushrod doesn’t care. The Vertical former with the hole in the middle is located in the fuse ahead of the stab slightly and keeps the fuselage from twisting in front of the stab. This former also keeps the fuse sides from flexing ahead of the stab and causes the fin to be much stiffer also.

The “V” is the width of the fuse at the exit holes…pretty easy dimension to get. Let the Teflon guide and the pushrod overhang the balsa sticks a bit. They will exit the fuse and you want that Teflon guide to be cut flush with the fuse sides making a friction free guide the entire length while inside the fuse. I use ¼ sq balsa for the cross pieces of the ladder. I build the “V’ up and glue it all with thin CA. Then take some ¼ balsa, light stuff say ¼” x ¾”, and make the supports that you see holding it in position in the fuse. Leave the assembly about 3” short of the Elevator Servo connection. The reason is you have to attach the pushrods to each other, and you have to have some sort of connector to attach to the servo arm. I’ll discuss the attachment to the servo later.

Important:
For a friction free setup the pushrods cannot have any bowing or bending from the fuse exit to the elevator control horn, or from the center of the fuse connection shown above to the servo arm. So it is very important to locate your fuse exits in the perfect location. I usually have my stabs done and completed. The stab mounted on the fuse and the control horns already on the elevator halves so I know the proper location. You also should have your elevator servo mount and servo with arm installed so that the angle of the ladder is perfectly setup as a straight shot inside the fuse. This is the most critical and most difficult of the install. Make your fuse exits slightly oversized to allow for a perfect location. Once you have the locations and everything trial fit, you’re ready to make the cross supports to hold the ladder inside the fuse. Oversized is good then sand them to fit further down the back of the fuse if needed. These are easy to make and need not be perfectly placed. Just make sure you are close to mid span and attached up front near the servo. The ¼” square balsa sticks with the Teflon sleeves attached are continued all the way back to the exit holes and actually glue to the fuse at this location. This gives a really solid support where the rods exit the fuse. This method gives 3 supports over the entire length of the pushrods while inside the fuse. Again refer to the picture #1 above for the installed setup. You can use more supports but its not needed. I would not use less supports than the 3 shown above..

One other note when cutting off the balsa sticks for proper length leave the Teflon sleeve and the CF pushrods alone and leave them really long. This will aid in future steps and setup.

When you have the ladder glued into the fuse, use extra epoxy with Micro balloons to fill the slot at the rear of the fuse for the pushrod guide exits. This makes them solid and you can cut the Teflon guides and sand flush with the side of the fuse. Idea here is just to make sure the Teflon tubing is totally surrounded or incased in Epoxy. You are not trying to fill the slot for painting just make sure that the Teflon sleeve is not going anywhere. Cut and sand the Teflon and any epoxy flush to the fuse side. Dips and depressions should be filled before primer and paint using lightweight auto body filler. I use Polyester glazing putty…Dries very quick and sands like balsa. Make sure to keep the Teflon sleeves clear of epoxy or filling putty.

Then you are ready to paint the fuse. Don’t use any special prep to your fuse exits and don’t worry about primer or paint clogging them up. Teflon is smooth and nothing sticks to it, not even your eggs. So when you’re done the little paint that gets inside will come right out.

Fuse is all done painted and its time to hook everything up.

Introduction

Servo and Elevator Connections