Building another JR SATAN

Very interesting user name given your location. I'm assuming that your choice is not by accident.

Welcome to the forum.

andrew

Welcome to CEF, Lieven.
When I built my 1/2A Li'l Satan I covered the whole wing with Ultracote and then used a hot Exacto blade to remove the covering where the booms were to be glued. Like Ken said, extending the sheeting to make the center section wider gives the covering something to adhere to after you make those cuts. Or, if you're using old time silk and dope, it's no problem, as you just glue straight to it and the glue soaks through the covering. I unfortunately realized that was a problem too late, when Andrew pointed out I would have a problem, and I had to cut strips of balsa to widen the center section.

In the first picture you see the part I cut to add onto the width. In the background you can see the original width the plans called for.


Now with the finished addition, when I cut the strips of Ultracote off to glue the booms, there is still plenty of area for my Ultracote to adhere to.


As for the washer, it is necessary to have some outboard thrust angle. There are wedges you can buy from Brodak that do a better job than the washer, as the washers can dig into the wood. The wedges come in a set of 1,2 and 3 degree offset.
http://brodak.com/thrust-wedges-1-2-3-degrees.html

I really like your work. Very clean job your doing there. I'm pretty sure it will "Haul the mail" as we like to say. Ken

Beautiful work AND beautiful photos !!!!

Welcome to the Forum !

Very clean woodworking --- I'll be following this build thread.

andrew

You do really nice work!

If the CG is still slightly forward, I wouldn't stress over it. My son flew mine and said it was twitchy. I'm inclined to think that the CG stated on the print is either scheduled to the rear too much or the 2" bellcrank is making the controls too sensitive. I have the controls operating with their slowest movements. I'm not sure what the spinner nut weighs compared to the stock nut and the Master Airscrews are a bit on the heavier side. I don't care for woodies on a combat plane but if needed a wood prop could be substituted to try and get some up front weight off the nose. I use golfers lead tape which is really quite thin and this could be used to wrap around the tail boom to give you even a bit more of adjustment. The plane really looks great. This will truly pay off in the finishing. I'm impressed you squeezed that tank in there. Ken

I've weighed several models at that stage of construction and I always think they are going to be nose heavy. But after adding paint and covering, I've been way off the mark every time. So I wouldn't put too much faith in a pre-finishing guess at its balance point.

You're doing such a beautiful job, I hate to give any opinions. But I can't help but think that most of your tank is going to be behind the preferred CG.

I usually put some shrink tube on mine. It helps keep the edges from catching on the hole in the rib where it passes through.

Lieven, here is what I discovered. Washers are stamped, this means that one side is slightly concaved. Place the convex side of the washer towards your bellcrank. It would also help to sand the bellcrank itself, either the bottom or the top. What's happening is the slight crush your providing is squeezing down on the bushing. It would be a benefit to use Nyloc nuts opposed to a regular nut. Only make it tight enough so there is no bind. I've used two nuts together using them as jam nuts and providing Loc-tite on the threads. In addition, the steel machine screws your using will work, but they are susceptible to bending. A socket head allen screw would provide far superior strength. Screws just aren't what they used to be. I say this in regards to if the plane was to lose line tension and fly out with a jerk. Wings like the JR somewhat fly on their own until they get up to speed and during takeoff, it can be a little eye popping at times. Yes to the above concerns you experienced as I've experienced the same. Just tighten the bellcrank enough and all will be good. Ken