Before I sound to nuts, just understand all the stuff I show you on this building loge is meant to express ideas and not to make the building of your 28 an exact science, this is meant to aid and exchange ideas with all. I will assume that all of us by now know now how to build at this level. I will try to show all the details in photos. When in doubt, ask a question, your humble servant.
The Kit comes with a retract installed. You have to mount the servo.
In this case I used a Hitec 5945 digital servo. I also fabricated a brake system using a second 5945 digital.
I used some left over servo mounts from Hock, you could use any aluminum right angel extrusion that’s light weight from the hardware store, the same as in John’s photo. The linkage is a carbon aero shaft with 4 /40 all thread inside with 4/40 ball links at each end.
The brake system is made with a brake kit from Fema Modelltechnik that fits a 127 MM wheel. The rest is made from 1/8″ aluminum plate and 1/2″ round rod. After mounting the servo and linkage I used braded fishing wire to connect the bell crank to the brake arm. This is done so the retract can rotate up and down and still have a positive connection to the brake.
One thing I would recommend, the aluminum collet on the main shaft that has a recessed 4mm alien screw that needs to be replaced with a 4mm external socket screw. Also make a flat spot on the shaft so the screw will seat and prevent it from rotating, this is done after you find the proper movement of the retract.