15 February 2020

Another busy week has just flown by: we’ve finished our lighting controller board, debugged our firmware and tested our LED strings… the simulator should be visible from the moon if not beyond! So we tweaked our code to protect our eyesight. We may want to add some more animation patterns later.

We wanted to focus on the mechanical controls and the interface between the electronics and the controls this weekend. Unfortunately, this meant working under outside. That plan was somewhat compromised with the storms battering the UK over the last week and this weekend, so we decided to shorten our working session today and take some cover.

We spent half a day with the air frame: identifying our requirements, evaluating solutions, measuring and generally discussing our options.

We think we can make this work using wire ropes and some additional parts:

  • We want to decouple the potentiometers and the controls. Our potentiometers wouldn’t last very long if we connected them directly to the control cables or rods. We’ve got several ideas for this which we’ll need to prototype and test.
  • For the rear seat air brakes, we will keep the existing rod and handle. We’ll attach the potentiometer in the wing box
  • For the front seat air brakes, we need to disconnect the existing rod, cut it and connect it to a new rod. The new rod needs to be routed to the wing box where we can attach the potentiometer.
  • For the front and rear trim, we are going to use wire ropes. 2 cables each attached to the trim levers. At the back, we will use metal plates on a pivot so there will be no need to use pulleys which could give us problems / stiffness with the 180 degree cable bends.
  • For the rudder, we will place 2 pulleys each behind the rear seat and loop the cables around them. This will create 2 x 90 degree bends per cable which should be manageable using 6×19 (fibre core) wire ropes.
  • We will use colour coded PVC coated wire ropes: green for trim (coordinated with the handles) and yellow for rudder.
  • We also need to allow enough wire rope cable to lock the support cradles together so that they cannot separate.

We’re also going to need to create more 3D printed parts than we planned originally.

Further research over the weekend allowed us to identify all the components we needed for our wire ropes (cable clamps, thimbles, turnbuckles to allow us to adjust the tension on the cables, locking carabiners, etc.). Hopefully this will all fit inside our budget as this is starting to get quite stretched already.

15 February 2020