RE: VQ P-61 CONTRUCTION
While I am at it here are a few pics showing some setup details. I am more of a builder than a flyer (I can out-engineer myself in a hurry!) but I really like the way most of my ideas on this plane worked out. So here are a few to consider...
I set up the flap linkage in a conventional manner to get good positive control of them, instead of going through the wing with the supplied linkage. I also got rid of the bellcrank on the center flaps and just added another servo. I had to expand the hatch openings a bit for the center flaps and then make new covers to mount the servos but this was pretty simple. One of the benefits of the ARC was that this sort of creativity was pretty easy without having to worry about the covering. The servos are tied together with a matchbox.
I am activating the gear doors using micro servos that are connected to the doors with custom-made ply horns. I used a JR channel expander to drive both the air valve and the three doors. The gear switch signal is programmed to go from one endpoint to the other in 2 seconds. First the air valve is tripped and the gear go up, then the gear door servos are tripped and the doors close. Toggling the switch reverses the sequence to open the doors and lower the gear. Using the channel expander also allowed me to set the endpoints for each of the gear door servos independently so that they close fully and are set even when they are opened. This works great and is very cool.
The gear doors are attached with regular CA hinges. The full-scale plane used "piano-wire" style hinges so this setup actually looks correct. There is a slight curvature to the main doors that I took care of by sanding a slight relief on the edge of the doors before covering them, so that the CA hinges would fit and work right. This could be a problem with using CA hinges on an ARF.
I used hard piano wire to connect the steering arm links to the servo. The ends at the servo hinge by using a combination of a pull-pull connector and metal clevis combination. The clevises swing outward when the gear is raised, hinging at one end at the servo arm and at the other at the piano wire/pull pull connection. This is very repeatable- I've cycled the gear many hundreds of times now and never a hint of a problem. We'll see how it works at the field.
Walt