Bruce dropped a not too subtle hint the other day that I was behind again getting this thread. Unfortunately Bruce was about as subtle as a 2 by 4 across the forehead!!
It's amazing just how quickly you can get behind in a project like this, especially when you have a building board filled with at least one project (I currently have 2 new builds going at the same time!!!). So let's see if I can't get some more of this build documented.
Next up let's go ahead and get our throttle push rod installed. On most kits it's up to the builder to locate where they are going to position the pushrod and it's tubing, but on our LT-40 the mounting holes are already located in both the firewall and former F-2 (picture #1 & #3). If you look at picture #2 you can see how the pushrod tube will run through the fuel tank compartment, running beside the fuel tank itself. I find it easier to put the tubing in place if you remove the foam padding from the compartment so it won't be way of our installation. If you're unsure about the exact position of the pushrod tubing you can refer to you plans to get it's location, but I usually just “eyeball” it. If you look in picture #3 you can see that I leave enough of the tubing so that it can “point” towards our throttle servo (once again, if you haven't glued in your servo tray yet you can temporarily locate it for this step). Once you have the tubing located where you want it you can secure it with a few drops of 5-minute epoxy (medium or thick CA will also work). With our tubing in place let's go ahead and put the actual throttle pushrod in place. Before we do that we can go ahead and put an EZ connector on throttle control horn on the carburetor. I like using the EZ connectors on the throttle because it makes it very easy to do adjustments of our throttle (picture #4). If you look at the position of the pushrod tubing and then the location of the carb you can see that there is a pretty ugly angle to deal with that. If you look at the plans you can see that a couple of quick bends of the pushrod will take care of this problem. I found that the easiest way to get these bends correct was to use the plans as a guide for bending the pushrod. Lay the pushrod on top of the plans and bend the pushrod to match the plans (pictures #5-#8). Now that we have the pushrod bent go ahead and slide it into our tubing starting at the engine in first. With the pushrod in place go ahead and connect it to the EZ connector on the carb control arm (picture #9). If you take a look at picture #10 you can see just how our bends look in place. At the throttle end I also used an EZ connector on the throttle servo (picture #11). Put the pushrod into the EZ connector on the throttle servo (picture #12).
Don't worry about making any adjustments right now. If you remember, I prefer to completely assemble the plane before I balance it. Then I will remove everything to cover the plane, so making adjustments now won't make any difference because we're going to remove everything anyway. All we are doing right now is getting everything in place so that we can check the balance of the plane. I won't elaborate about taking everything off and putting back on later on , but don't worry because I will explain how to make all of the needed adjustments down the road.
I want to take few minutes to talk about the EZ connectors. I know that there are plenty of pilots out there that will disagree with me about this, but I just don't like to use EZ connectors on any critical control surfaces (i.e. Elevator and ailerons). Since an EZ connector has a screw holding the control rod in place it's possible for that screw to come loose which will cause you to lose control of that surface. If that happens to be the elevator or ailerons you can say goodbye to the plane because you won't have control any longer. For those surfaces I prefer Z-bends, L-bends, or solder clevises that won't come loose. But for things like throttle or rudder the EZ connectors are great. If the connector comes loose on the throttle you will lose control of the throttle, but that's not a big deal. It means that you will either have a dead stick to land or your throttle will go full open. If that happens you simply fly around until your plane runs out of fuel and then you land dead stick when the engine dies.
Pictures
1. Predrilled hole in firewall for the throttle pushrod tubing.
2. Remove the foam padding in the fuel tank compartment to install the tubing.
3. The pushrod tubing exits into the body of the fuselage
4. Install an EZ connector on the carb control arm
5. Use the plans as a guide for bending the throttle pushrod
6. Use the plans as a guide for bending the throttle pushrod
7. Use the plans as a guide for bending the throttle pushrod
8. Use the plans as a guide for bending the throttle pushrod
9. Tighten down the EZ connector on the pushrod
10. View of the bends in the throttle pushrod
11. Connect the pushrod to the throttle servo
12. Connect the pushrod to the throttle servo
Until next time
Ken