Dubro Tailwheel installation
07-01-2008 | 02:38 AM
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From: Cape Town, SOUTH AFRICA
Dubro Tailwheel installation
I am finishing off a 4*40 and have bought a Dubro 40 size tailwheel bracket for it to replace the stock arrangement.
The instructions for the installation are a little vague and I have the following queries concerns.
1. The packaging instructions recommend to install the bracket using blind nuts - this is not possible on the 4* as the tail section is closed off. Will self taping screws with the threads hardened with CA be OK? Also due to the slope of the fuse floor the back of the tail wheel bracket is not in line with the rudder hinge line. I could either sand a recess into the fuse bottom to accomodate the bracket (but this looses material for the screw to grip or add a balsa/ply packing piece.
2. The profile of the bracket is larger than the fuselage ie the bracket hangs over the fuselage sides. I don't like this but sanding down the bracket to match the fuselage will remove most of the stiffening shear web of the bracket. What have other builders done here?
3. What is the best way to attach the wheel wire to the rudder? To make an "L" bend and run the wire vertically up the hinge line or make a long "S" bend and run the wire along the bottom of the rudder ( Similar to a Sullivan tail wheel assembly but without the spring).
I am concerned that the space required to make the "S" bend will be greater than the available space.
Any other tips or recommendations?
Andrew
The instructions for the installation are a little vague and I have the following queries concerns.
1. The packaging instructions recommend to install the bracket using blind nuts - this is not possible on the 4* as the tail section is closed off. Will self taping screws with the threads hardened with CA be OK? Also due to the slope of the fuse floor the back of the tail wheel bracket is not in line with the rudder hinge line. I could either sand a recess into the fuse bottom to accomodate the bracket (but this looses material for the screw to grip or add a balsa/ply packing piece.
2. The profile of the bracket is larger than the fuselage ie the bracket hangs over the fuselage sides. I don't like this but sanding down the bracket to match the fuselage will remove most of the stiffening shear web of the bracket. What have other builders done here?
3. What is the best way to attach the wheel wire to the rudder? To make an "L" bend and run the wire vertically up the hinge line or make a long "S" bend and run the wire along the bottom of the rudder ( Similar to a Sullivan tail wheel assembly but without the spring).
I am concerned that the space required to make the "S" bend will be greater than the available space.
Any other tips or recommendations?
Andrew
07-01-2008 | 05:27 AM
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From: Indianapolis, IN
RE: Dubro Tailwheel installation
ORIGINAL: Andrewmc
I am finishing off a 4*40 and have bought a Dubro 40 size tailwheel bracket for it to replace the stock arrangement.
The instructions for the installation are a little vague and I have the following queries concerns.
1. The packaging instructions recommend to install the bracket using blind nuts - this is not possible on the 4* as the tail section is closed off. Will self taping screws with the threads hardened with CA be OK? Also due to the slope of the fuse floor the back of the tail wheel bracket is not in line with the rudder hinge line. I could either sand a recess into the fuse bottom to accomodate the bracket (but this looses material for the screw to grip or add a balsa/ply packing piece.
I would install a 1/8 inch plywood mount on the bottom of the fuse if you do not have one now. Use screws to fasten the bracket to the ply plate. Screws will hold just fine. The blind nuts if used should be installed before closing the back of the plane.
2. The profile of the bracket is larger than the fuselage ie the bracket hangs over the fuselage sides. I don't like this but sanding down the bracket to match the fuselage will remove most of the stiffening shear web of the bracket. What have other builders done here?
I would not sand down the tailwheel bracket. Your correct about compromising strength.
3. What is the best way to attach the wheel wire to the rudder? To make an "L" bend and run the wire vertically up the hinge line or make a long "S" bend and run the wire along the bottom of the rudder ( Similar to a Sullivan tail wheel assembly but without the spring).
I am concerned that the space required to make the "S" bend will be greater than the available space.
I bend the tailwheel wire rearward just under the bottom of the rudder. Then attatch the wire with fuel tubing over the tailwheel wire and a "U" shape bracket connected to the rudder with small bolt and nut.
Any other tips or recommendations?
Andrew
I am finishing off a 4*40 and have bought a Dubro 40 size tailwheel bracket for it to replace the stock arrangement.
The instructions for the installation are a little vague and I have the following queries concerns.
1. The packaging instructions recommend to install the bracket using blind nuts - this is not possible on the 4* as the tail section is closed off. Will self taping screws with the threads hardened with CA be OK? Also due to the slope of the fuse floor the back of the tail wheel bracket is not in line with the rudder hinge line. I could either sand a recess into the fuse bottom to accomodate the bracket (but this looses material for the screw to grip or add a balsa/ply packing piece.
I would install a 1/8 inch plywood mount on the bottom of the fuse if you do not have one now. Use screws to fasten the bracket to the ply plate. Screws will hold just fine. The blind nuts if used should be installed before closing the back of the plane.2. The profile of the bracket is larger than the fuselage ie the bracket hangs over the fuselage sides. I don't like this but sanding down the bracket to match the fuselage will remove most of the stiffening shear web of the bracket. What have other builders done here?
I would not sand down the tailwheel bracket. Your correct about compromising strength.3. What is the best way to attach the wheel wire to the rudder? To make an "L" bend and run the wire vertically up the hinge line or make a long "S" bend and run the wire along the bottom of the rudder ( Similar to a Sullivan tail wheel assembly but without the spring).
I am concerned that the space required to make the "S" bend will be greater than the available space.
I bend the tailwheel wire rearward just under the bottom of the rudder. Then attatch the wire with fuel tubing over the tailwheel wire and a "U" shape bracket connected to the rudder with small bolt and nut.Any other tips or recommendations?
Andrew
07-03-2008 | 03:03 AM
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From: Cape Town, SOUTH AFRICA
RE: Dubro Tailwheel installation
Here are the pictures of the finished tail wheel. I removed the tyre from the wheel when soldering on the washers, probably not necessary - but just in case, I still consider myself to be a novice solderer, generally happy with the result though.
Bending the wire tightly enough around the collar (and square to the tail wheel portion) was quite a challenge but also with a tweak here and there got it pretty muuch spot on. Even with the 90 degrees bend as tightly as I could make It I still needed to add a piece of ply under the fuselage to provide enough clearance for the tiller. This still needs to be shaped to blend in with the fuselage.
The fuel tubing method was easy to do and is completly effective.
Is it advisable/necessary to insert the fixing screw into a hard wood block in the rudder. As it stands I have just screwed it into the balsa and hardened the threads with CA.
Bending the wire tightly enough around the collar (and square to the tail wheel portion) was quite a challenge but also with a tweak here and there got it pretty muuch spot on. Even with the 90 degrees bend as tightly as I could make It I still needed to add a piece of ply under the fuselage to provide enough clearance for the tiller. This still needs to be shaped to blend in with the fuselage.
The fuel tubing method was easy to do and is completly effective.
Is it advisable/necessary to insert the fixing screw into a hard wood block in the rudder. As it stands I have just screwed it into the balsa and hardened the threads with CA.
07-03-2008 | 05:37 AM
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From: Indianapolis, IN
RE: Dubro Tailwheel installation
I just use a thin aluminum strap and put a screw or bolt and nut throught the aluminum strap, rudder and out the other side. This seems to be a failproof setup for me. I do not see why your set up would not work just fine though. I would harden the wood with ca and use a long screw.
07-04-2008 | 08:15 AM
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From: Lake Ronkonkoma,
NY
RE: Dubro Tailwheel installation
Just a thought; your tailwheel strut looks almost vertical. My experience is that this will make ground handling a bit squirrely, that is overly sensitive. I would suggest that you bend the strut towrad the rear to add a little caster for improved steering.
07-04-2008 | 11:40 AM
#8
RE: Dubro Tailwheel installation
To attach the wire to the rudder, I like to use the Goldberg Adjustable Horn Bracket http://www3.towerhobbies.com/cgi-bin...?&I=LXDMK2&P=0 . The tab goes in a slot cut into the bottom of the rudder and the wire goes through the cylinder.
Clean, neat and easy to work on.
Dave
Clean, neat and easy to work on.
Dave
