I am about to build a Hobbico Avistar ARF. I'd like to configure it as a tail-dragger and I could use some input on which tailwheel assembly would work best for this. I've looked at Sullivan, and Goldberg but they all look like the bottom of the rudder must be in line with the bottom of the fuselage. This is not the case with the Avistar. In fact, the rudder ends above the horizontal stab. Any suggestions you have are welcome especially if you've made the same conversion! - I've seen some pictures so I know it can be done. Could also use ideas about where to mount the main gear and reinforcing the fuselage at the connection point.
Here's one way to do it. Slice the balsa off of the bottom of the fuselage and replace it with a piece of hard 1/8 plywood to mount the tailwheel bracket. If you want to use a Du Bro bracket (the one I'm most familiar with), you can use a piece of 1/16" music wire with an axle bent in one end for the wheel, and a long stem that will go up through the fuselage and be in line with the rudder hinge line. When you're ready to put it together (after you've monokoted over the new plywood mount on the bottom and drilled your holes) run the long stem up through the fuselage, screw the mount on, and then bend the top of the wire so that it points backwards to make a tiller arm. Make sure that your tiller arm is in line with the wheel. Trim the arm to about an inch or an inch and a quarter long. Then attach it to the bottom of the rudder for steering. This can be done in a couple of different ways.
Some guys put a piece of nylon, such as those cheap bendy nylon hinges, around the wire in the shape of the letter U to strap it to the bottom of the rudder, and run a screw through the nylon U to attach it to the rudder. Don't forget to harden the balsa around the screw by perforating it with a pin and applying thin CA. My personal favorite method is to get a piece of small wire and bend an eyelet into one end, and leave about an inch to an inch and a half of straight wire. Push this up into the bottom of the rudder, then harden the spot where it went in with thin CA. Then put a piece of SMALL (not medium) fuel line on the tailwheel tiller arm and insert it through the eyelet so that the fuel line acts like a grommet in the eyelet. Generally this has to be done at the same time that you are putting the rudder on with CA hinges, because you can't move your tailwheel tiller arm around once you stick the wire up from the bottom and bend it back. This is a good method, but it doesn't work so well when the rudder is already firmly attached.
The first reference by Reynolds, to the tail wheel is two great ways of installing a tail dragger wheel, you can also find those tail wheels that use a spring that is attached to the rudder, in which activates the tail wheel or the type that have horns on each side of the rudder that also activate the tail wheel. Either way you chose, all these work great. About the front landing gear, the front wheels should appear in the middle of the leading edge of the wing, looking straight over the wing, the axle should be seen looking straight down over the leading edge. Inside of the servo well, fit a piece of plywood at the floor, where the mounting screw will be installed to hold the gear, reinforce this plywood with triangle stock along the sides.
One idea is to mount the bracket like Robbie said, but instead of burying the tiller arm in the tail, bend it straight back with a small hook on the end. Then, insert a T-pin in the bottom trailing edge of the rudder and put a rubber band or spring between the two. This might save your rudder servo if the rudder is inadvertently pushed over.
I have seen another assembly that utilizes an attached horn. This was connected to a second pushrod back to the rudder servo. Seems logical - kind of like a push-pull system. Thoughts?
Sorry this took so long. This is a link to my hangar at RCU. There are three pics of the conversion there. I've had it in the air since and it flies good. Ground handling is surprisingly true. It gets up quickly and landings are smooth as silk. I would especially advise this conversion to anyone flying off a grass field.
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I apologize if this doesn't come out as an actual link. I couldn't find any other way to do it except paste the URL in.
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