Yoke build update

I had planned to leave this post until later in the yoke build, but since I anticipate that it might take a few more weeks to finish completely, I wanted to post some pictures for the curious. This post is going to be largely content-free and photo-heavy.

First off, I did the electronics for the yoke handles. These have a large number of buttons on them and an 11-wire cable ran from the handle to the yoke innards. This cable had to be cut to take the thing apart, and I needed a much longer length of wire anyway, so I had to re-join it. I looked at a replacement but this would have involved a lot more soldering on parts that I could not afford to damage. My soldering is decent, but not factory-quality. I bought a temperature-controlled solder-station, because my previous fixed-temp iron just wasn’t doing the job. I found I needed a very high temp to work accurately with the high-silver content solder I’m using.

My lovely new temp-controlled solder-station

Joining the wires was accomplished using bridge boards. These are small pieces of veroboard with the right number of tracks for the wires in use. You solder the wires from each cable onto either end of each track. While you can in theory just wrap and join individual wires and then insulate them, with very thin wires such as those used in microelectronics it’s very hard to do so and the cable tends to remain brittle and breaks easily. The bridge board solution avoids that, because once you’ve soldered all the wires down you can cover the board with hot glue, turning it into a solid lump. I inserted a bridge at each end, one of which lives in the assembled yoke handle and the other of which goes inside the box of electronics I made from the CH yoke controllers.

A bridge board used to connect cables with very thin wires

Once soldered, the board is covered in glue to protect the wiring

The electronics box was a large mains junction box I happened to have handy. It was the right size to glue down the CH control boards while also providing a surface to expose the inputs for the potentiometers etc using standard plugs. The X and Y axis pots for each yoke are exposed as 3.5mm stereo jacks, carrying the three connections needed, while I used a pair of 8-way phono socket boards to expose the switch connections for the manual switches that appear on the front of the yoke case, and two of the three extra potentiometer axes on top of the yoke. Since these can be re-purposed for other inputs and controls using FSUIPC later, it makes sense to preserve them. I also cut holes and cutouts for the various input cables – USB cables, cables from the yoke handles, etc. Once screwed together this does a good job of hiding all the wiring. More photos of this in a future post.

The PCBs from both CH yokes are glued into a plastic utility box

The potentiometers connect via 3.5mm stereo jack plugs

The physical mechanism of the yoke is similar to Ken Brand’s design, as I mentioned in my previous post. An assembly with two pillow-block bearings takes the yoke rod and allows it to rotate smoothly. This whole assembly is then mounted on drawer-rails which allow it to slide back and forth, giving us the two axes of movement that we need. The assembly itself is very simple – a piece of very stiff MDF board with batons screwed in place at the sides on which to mount the inner portion of the drawer rails, and then two more batons to which the outer portion of the rails is mounted, which are then held in place underneath wooden planks using steel corner-fasteners, so they can be removed easily.

The yoke-holder assembly in place on the frame

Having built the frame to receive one of these assemblies, I test-fitted it and then placed a yoke rod in it and successfully moved in in both axes – the movement is nice and smooth though I think the drawer rails will need a little bit of oiling to make them perfect. I then replicated the frame and assembly on the other side of the cockpit. Eventually, the two assemblies will be connected so that when one moves, the other moves similarly, and the two yoke rods will be connected with a chain so that when one rotates, the other one does too.

Yoke rod in place and at maximum inward deflection

The yoke at maximum outward deflection

The right-hand yoke-holder assembly

Now, I need to figure out how to attach the potentiometers to the assemblies to measure the axial movement. This will take quite a lot of trial and error, I think. I also need to work out how and where to attach bungee cord – elasticated rope – to provide both resistance to movement and auto-centering of the yoke in both directions. Then I’m ready for a very early test flight!