In the spirit of getting things done as soon as possible, we completed most of the design of the control system in two weeks. The majority was straightforward; we referenced the Legal Eagle and Affordaplane, as well as previous research while designing the system.
Previous Decisions
Previously, we decided to make our control system almost entirely out of cables, to save weight. We had already decided on our rudder and elevator geometry (roughly), and the hinges we will be using (airdomes), so we worked around those constraints. We will use bellcranks similar to the Legal Eagle’s for our elevator and rudder, threading them onto the rudder and elevator pipes. The majority of the aileron control system had already been decided before we worked on the rest of the control system.
Rudder Pedals and Control Stick
After deciding on the bellcranks, we designed the rudder pedals, which we based heavily on the Affordaplane’s, and the control stick. The rudder pedals will be mounted on one of the horizontal beams on the floor of the nose, and the control stick will be mounted on a sleeve on a beam just aft of the rudder pedals
The blue lines represent the aileron cables, and the black lines represent the elevator cables.
Routing
Our final step was routing. We decided on using 3/32” stainless steel cables of 7 x 19 construction, which are the norm for ultralights, and can take around 900 lbs of force (we’re only expecting around 100lbs of force). We’ll use tin-plated copper Nicopress sleeves to secure the cables — they were the cheapest option (swaging requires machines that cost thousands of dollars, and stainless steel Nicopress sleeves, though stronger, may need hydraulic tools, which are expensive). To direct the cables, we’ll use fairleads and pulleys — the exact details of that will be worked out when we build the control system.
The red line represents the elevator cables, the blue line represents the rudder cables, and the green line represents the aileron cables.
