This article demonstrates how to create a simple Steerable Tailwheel landing gear for your FT Mighty Mini scratch build. Following the FT philosophy of "keep it simple" this can be made from parts you already have. Unlike most main gear installations all your bends can be inexact and it will still work fine. I know that a skid would work fine but this adds about 1.3 grams and makes your plane fun to taxi.
1) Gather the following materials
15 cm of 0.81 mm piano wire (.032")
1 each used Prop (a soft black Gemfan 5x3 works great)
1 each Prop Adaptors
1 or more used Ink Pens or used mechanical pencil
2) Remove the ink cartridge from the used pen.
3) Cut the clean portion of the tube off the ink cartridge and dispose of the remaining cartridge.
Approximately 40 cm of clean tube will be necessary so if you're using new pens it might take a couple. You don't need to cut the tube into parts yet, but eventually 4 separate pieces are required : 1 each 5 mm collar, 2 each 15 mm guides, and 1 each 8 mm axle bushing
4) Create the tire portion of the wheel
Break the remaining blades off the used prop hub and carefully cut the rough edges off. Finish with 200 grit sand paper until smooth . Note the soft Gemfan prop works great for this, but I would not even attempt to use a DAL prop. This sounds like a lot of work but the Gemfan props are really soft and takes only a few minutes
5) Determine the correct prop adaptor insert to use.
Select the adaptor that fits your clean tube best
6) Paint your parts.
I used a silver Sharpie for the hub and black Sharpie for the tire portions. If you have a black prop to start with it will look a lot better
7) Bend a square with the wire to form the axle.
You want it small but also large enough to allow the wheel assebly to roll freely. I have found that I can keep my bends small with sharp angles by forming it without the wheel installed.
8) Prep & Install the wheel Assembly.
After getting the wire shape as square as possible without the wheel installed. Put the prop adaptor into the prop hub and install both onto the wire square. Note you will find that the assembly will slip around even sharp corners at this point.
9) Bend the wire leads vertically (see the photo for correct orientation)
10) Create and install a binding collar.
Make a collar from the clear tube. Cut a piece of clear tube approximately 5mm long and install it to bind the wire ends as shown. Note how well this cleans up any bend imperfections.
11) Form the rudder guide
Bend the longer wire end just short of 90 degrees to eventually align approximately with the rudder.
12) Form the axle bushing
Cut a length of tube just short of the axle width. Slit one side of the tube the entire length. If you kept wire square tight it should be about 7 to 10 mm in length
13) Install the axle bushing
Deform and slip the tube onto the axle as shown below. Slide the tube though the prop adaptor
14) Finished axle bushing installation
It should look like the photo below. Apply a drop of CA to hold tube the prop hub if desired. Note the bushing provides the rolling surface of the wheel assembly on the axle and prevents the assembly from riding up the side of the wire square while removing most of the sloppiness. Look at this carefully to see what's going on here.
NOTE: The split tube axle bushing is trapped by the prop adaptor while the wheel is centered and trapped by the bushing. CA or not this is never going to come apart
15) Cut two guides from the remaining tube
Cut 2 each pieces of clean tube to form the vertical stabilizer pivot point and the horizontal rudder slider. Both should be 10 to 20 mm long. The completed tailgear assemble is shown below with both guides installed and it weighs in at 1.3 grams
16) Prepare the fuselage for the tail gear installation
With a wood skewer poke a hole in the fuselage and vertical stabilizer assembly as close to the rudder as practical.
17) Insert the vertical stabilizer guide tube
Dab a little hot glue into the hole push then push the vertical stabilizer guide tube in until flush with the fuselage. Note in the photo below the tube is not pushed in completely and thus does not show the completed installation
18) Install the tailgear assembly into the vertical tube
19) Secure the horizontal tube slider onto the rudder
Make your final adjustments to the tailgear assembly and secure tube horizontal slider onto rudder with hot glue. Note once secured the assembly should be somewhat sprung against the fuselage if it is installed correctly. Cut the horizontal wire to length but note it should always extend past the end of the slider tube to prevent it from jamming
This same technique can be scaled up for larger aircraft. Hope you got a least one good idea from this article. Thanks for looking and good luck your builds!
Wheel for my FT 3D next to the mini