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

Thanks Ken for this precious info. I've read your topic on your JR SATAN. You did a wondeful job. I will keep you posted.

Lieven

Andrew, your spot on. We must not forget.

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

Thank you Rusty. I'll have a look on the Brodak website. I saw your Li'l Satan on Youtube, it goes like the clappers.

Hello everybody,

Here are a few more pics. Installed the bellcrank and some part of the sheeting for the mock up with tail booms and elevator.





Have a good weekend,

Lieven

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

Thanks Ken for the encouraging comments.

I'm busy making the tail booms. As mentioned above, I made them longer as per Ken's advice to compensate for the engine's weight. One is already finished. Making a second one identical is not so straight forward but we're getting there.

Lieven

Hello there,

After a lor of sanding and comparing, I finished the tail booms and also glued the plywood doublers in place for the hinge pins. The hinge pin holes still need to be drilled trough. The tail booms wedge on nicely on the wing to get a snug fit. Here are some pics







Lieven

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!

Thank you for your comments.

The elevator has been cut out of 3 mm sheet. I use a long hinge pin as Ken said to compensate for the engine's weight. It's a 2,5 mm pin with both ends bent and that goes through both tail boom holes. As it is difficult to drill a 2,5 mm hole into a 3 mm edge - at least for me, it is- I cut slots into the elevator. These will be covered by pieces of shaped hardwood on both sides. In order to locate the hinge pin, I've cut a 90° V groove into the forward edge of the elevator with an Xacto knife.

Unfortunately, I realized too late that now I have to cut the hinge pin in half to slide it through both tail boom holes. But on the other hand, bending the wire in a vice with both tail booms in place would end up in catastrophy.

The next step will be fabricating the control horn and then get on with the mock up. When reading Kim's thread about his Shark, I think I will have to put some lead on the tail as well. We'll see... Here are some pics.

Lieven

Hello everybody,

Did the mock up and positioned the plane on a 3mm plywood edge.
Every element was added on except:

part of the sheeting
covering
silicon tube
exhaust
paint
cowling

The CG found is about 6mm in front of the CG indicated on the drawing. Is that all right? What are the differences in flight? The weight at this stage is about 380g.
If you lot see that there's something wrong or it's going the wrong way, don't hesitate,..just shoot!!

Lieven

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.

That's right about that tank position, Rusty, the indicated CG is between the forward bellcrank hole and the forward edge of the belcrank mount. Should I put the tank in the middle between the leading edge and the spar?

Here's a small update of the JR Satan's construction. I've been busy working a lot and therefore, it slowed down a bit. I fixed the tank and put the leadouts onto the bellcrank. I put epoxy onto the copper binding wire and hung it up to dry. Should I put shrink wrap on there after drying just to make it more smooth?

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.

While mounting the Brodak 2" bellcrank and doing up the nut, I found that the bellcrank itself became more stiff in turning. The pedestal protrudes the bellcrank surface, so I thought that the washer edges might touch the bellcrank surface. I replaced the 1/8 washer by a 3 mm one (small washer on the picture) with an enlarged hole but I didn't gave any difference. Could it be that the force needed to squeeze the spring washer between the washer and the nut crushes the pedestal slightly making it to expand? In that case I'll remove the spring washer and use Loctite for securing. A nyloc washer would be ideal but finding a 1/8 UNC over here is almost impossible. The smallest one you can find is 1/4.

Did anybody encountered similar problems with this type of bellcrank?

Lieven

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

Hello Ken,

After reading your advice, I had a look again. I noticed that without the nut mounted, the bushing turned with the bellcrank. When everything was done up, the bellcrank turned with a greasy feel on the immobilized bushing. I passed over it quickly with fine sand paper and the problem was solved. Proof that Brodak parts are manufactured with precision (except for the stamped washer?).

Lieven

This is how the plane looks today with finished aft part:





To get the fairings aligned with the horizontal centre line if the rib, I drew the bisector of the trailing edge angle on the inside of each inner tail boom before assembly. In order to get exactly the same marking on the other side, I drilled a small hole to indicate the alignment. This hole is covered when the fairings are glued on.



Lieven