Front Gear Assembly - Part 1

Front Fork Installation

The front fork installation is quick and easy to complete.

  Tip#1

The fork can accidentally be installed 180 degrees off, there is a much larger lip on the "front" of the fork to help orient the part in relation to the nose gear tube.

Although not shown in the picture above, I deferred installing multiple parts to make the assembly easier to move around due the weight and size.

• Wheel and tire
• Wheel spat mounting brackets
  

Nose gear strut and engine mount

This part of the installation was time consuming for many builders and I was no exception.

 

 

The Vesconite bushings are cut in half on the lower bushing location and use an unmodified bushing on the upper mount.

The upper bushing fits firmly in the upper bushing mount, I used a rubber mallet to "gently" knock the bushing into place.

The upper bushing fit squarely and aligned with the upper hole in the engine mount as shown below.

 

The lower bushings must be sanded to reduce the turning force required to rotate the nose gear assembly.

I followed another builders recommendation (Patric Shine) and sanded using sand paper to enlarge the bushings.

I used 400 / 500 grit to slowly remove material then re-assembled and rotated the tube back and forth.

Using this method I could see where the tube was binding on the bushing and continued to sand until these areas were uniform across the face of the bushing.

The dowel method probably would have been faster overall but I think both methods get the same results.

This is another builders image, as I lost a number of pictures during a phone upgrade.

Here is another example by builder Olivier Mo:

With the Vesconite bushings sanded down and 800/1000 grit sanded back to a glossy finish I moved on to securing the bushings using the node gear bushing locking brackets. This is where things took a tune that I wasn't expecting, the brackets fit but threw the bushings out of alignment.

The lower split bushings, retainer brackets and bolts fit just fine, however; the upper brackets for the solid bushings would not fit with the bolts inserted.

You can see in the picture below that the alignment pin I was using and just how far the locking plate was from aligning with the pin.

 

If you tried to force the bolts in which I could do, it would change the alignment of the upper bushing resulting in excessive force required to turn the nose wheel tube.

I talked to the factory about it like many others have and the response was always to keep sanding the bushing.

After a many days of staring at the problem I began to suspect that the bushing wasn't the problem and I started looking at the slots where the locking plates insert around the bushing.

The upper locking plat inserted easily and without resistance.

The lower locking plate had to be forced in, which caused the bushing to shift from it's nature location in the slot.

I noticed there were several witness marks on the lower plate which lead me to look at the welds inside the locations highlighted below.

One both sides the welds were much taller and had a lot of slag on the mating surfaces.

Lightly cleaning up these welds and removing the slag from the mating surfaces completely resolve the locking plate binding issues.

Now that the bushing wasn't being twisted inside the mount the turning resistance was significantly reduce.

I still needed to sand the bushings because I could see witness marks on the inside the bushing where it was out of alignment.

Using a similar method to the lower bushing I started with 400/600 grit on the and kept reinstalling the bushings and brackets till I could see an even wear patter on the surface of the bushing. I cleaned up the bushing with 800/1000 grit paper until the insides were a shiny smooth surface.

The bolts were again installed to secure the bushing and plates and the force required to turn the assembly was minimal.

Control Installation - Part 3

Control stick installation has begun.

 

This part came pre-assembled at the Sling factory, and I took it apart, well sort of...

I removed the control stick from the assembly and sent it off to be powder coated. During final assembly it will sill need to be cut to length, but that is a problem for another day.

Prior to final installation of the left and right control tubes I marked, drilled and riveted the bushing locking collars in place. This did require these parts to be temporarily installed to mark where the locking collars would site without binding on the bushings.

I had issues with binding on these bushings, so I used the same techniques described in the elevator torque tube sections so that I have a nice fluid range of motion.

Adding Lithium grease on these bushings really helps reduce overall friction in these areas.

Tip #1

Prior to finial install, multiple builders have recommended pre-installing the eye bolt hardware as well as the control stop spacers.

Tip #2

Although the finishing manual does not specify the installation of both control stops on each control tube, I followed the advice and experiences of other builders and used all four control stops, two per side.

This change did require longer bolts to be used HW-ANB-416 (AN4 - 16A Bolt)

Using both control stops on both tubes makes it really easy to align the control sticks using the aileron push-rod tube.

Tip #3

I also installed the Garmin GSA-28 aileron servo before this section becomes too cluttered with control linkage making it difficult to access.

Access to mount the AP servo using the bolts specified in the KAI are a challenge because it is mounted inside the spare carry-through and the bolt lengths are short.

With the control tubes installed I needed to secure the aft bushing mount to the cross-member on the spar carry-through.

 The instructions for this section are pretty much non-existent and the quantities in the inventory do not align with the requirements, correct quantities are listed below.

• (8) - HW-SBM-416 (M4 x 16mm) button head screws
• (8) - HW-MTW-040 M4 Washers
• (8) - HW-MTL-040 M4 Nyloc Locknut
   

Tip #4

I replaced the factory supplied HW-SBM-416 (M4 x 16mm) button head screws with shorter (M4 x 14mm) because it is impossible to insert these screws without damaging the threads using the length supplied by the factory. 

You can see in the picture below that it still requires some force to push the screws into place. (scratches on the spar carry-through top plate)

You can see in this view the the slightly shorter screws still expose more that enough thread after the Nyloc locknuts have been installed. I could have probably used an even shorter (M4 x 12mm) based on the length exposed, however; changing it now would not result in any improvement.

Tip #5

Some builders have been instructed that they may need to slightly bend the support bracket that carries the bushing to improve alignment if there is excessive binding. I wasn't aware of this at the time so I struggled with sanding the split bushings to get the proper fitment.

Notes:

1. Installing the eye bolts and aileron linkage ahead of time will make things far when connecting everything during final assembly.

2. Completing the push-rod installation outlined in the finishing construction manual will also help to close-out this section and test all of the control linkage prior to final assembly.