And... we’re back!
After a long break I’m back on this beast.
I’ll begin with the wings. What I did to improve the stance and stability of the plane is also the thing I’m fighting when it comes to door hinge angles. The stock ARF door hinges are poor to begin with. I’ve torn them out a while ago but look at the photos from last September up above here. They are simply aluminum tubes epoxied with globs of micro balloons and somehow aligned. Because I relocated the extracts about 10mm forward of the original position I had to remove the strut door hinges. Then I had to make new low profile stronger hinges. The gear is as far forward as I could get it and the axle position is pretty much in the correct scale location within about 1/4 inch. When you watch videos of this plane taxiing on grass you see how unstable it is because the axles are too far back. It wants to tip the nose down especially with this much weight, Kolm 150 3cyl, in the nose. I’m really looking forward to seeing how this plane tracks with this modification.
On the doors...
Learned a few things so I’ll share my notes;
Outer doors, you must align the door hinge pin from the top view (actually the bottom of the wing looking at the retract) It has to be parallel to the retract pivot axis. The door on my build is not aligned to the strut, they are not parallel, but the hinges have to be in order for them to move together correctly. From the side view, the door hinge will be set by a couple of relationships. The door relative to the wheel rim when open for the best scale look so that’s a for/aft alignment. Second is the door closed so it is even with the wing when closed and seated. This will set the pin axis in the best location so the door moves well with the retract.
I used Dubro 2-56 for 4-40 and 4-40 for 4-40 swivel links with a cut 1 inch 4-40 screw. The stock Sierra Retract drag links look great but they are fixed, no pivot action, and will not work for me.
The collar on the strut can be adjusted and I took a look at the full scale links to get an idea of how them move. The basic position works for the model as well. The links are angled down. The pivot location on the doors are basically aligned with the lower cross rib detail molded in the door. Just picked a decent looking location and worked with it.
The new hinge is built with brass tube, hard wood, epoxy and fiberglass. I made a small wood wedge and tweaked it until the angles worked and CA glued the brass tube so it wasn’t permanent. I made a small frame work from plywood to anchor the hinge pin to the wing panel.
The gear door mount on the wing panel is tricky because you have to allow the pin some room to be moved. In my case I have a very tight space at the front of the wing to work with. I used a brass servo grommet to work as a bushing and it’s glued in the plywood rib. Taking advantage of the grommet I drilled the hole and filed it as a slot to give me the ability to move the hinge pin around.
This part has been tedious and time consuming!
The outer doors...
The hinges are more of the same so I removed them. The problem with the inner door hinges is simple but challenging. The hinge center line is basically on the skin of the door and next to the edge in order for it to work right. The real door hinges are very small and riveted to the door skin. To make something like this work on the model I used the largest Robart pin hinges and put them in the same basic position. If the hinge pivot center is in a different location you will have a huge gap between the door edge and the wing center rib. The full scale plane has large panel gaps in the same location for the same reasons.
Last edited by Chris Nicastro; 06-11-2020 at 08:59 PM.