Repair of the JR SATAN

Lieven, Don't forget... hard balsa and excess glue add weight! Your building skills are incredible. I believe that if you had a hard balsa leading edge, there could have been more serious structural damage that "might" have even been hard to detect. It's fairly plain to see that the damage is localized to that area.

In my opinion, your wing "as built" had the perfect "crumple-zone" for such an impact. The spar looks undamaged... and that's really the only part where you want the most strength in a wing. The replacement L/E could be joined near the root, with a short (1") piece of aluminum tubing roughed-up and "dowelled" in, for support. Keep your repairs "A"-grain lightweight balsa. On internal structures that have broken or need strengthening; I cut small patches of fiberglass window-screen mat'l. and bridge the joint/break... "tacking" with CA... then brushing-on epoxy using a short-bristled plumbing flux brush. It forms a lightweight and very strong patch.

Here's a photo that shows a joint that I chose to strengthen in this way.

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It looks to me that the leading edge notches were cut a little deep. It may just be the picture though.

The good thing is it's a quick repair.

Ron

It seems that me and Roddie have opposing views on builds. Roddie prefers crumple zones and I prefer aeroplanes that will bounce of the ground.

My favourite control line, apart from "Blue Pants" was the "Dominator" - the Dominator was a survivor. Definitely hard balsa leading edge! Although some used soft balsa at the front of it because it was easier to sand but only for the rounded portion. You can see this in the contructor's link below.

http://www.flyinglines.org/kb.dominator.html

Ken is one of the guys we fly speed and combat with. Most of the combat guys around here fly the dominator in D-bat. they are very tough.

ian1954 wrote:It seems that me and Roddie have opposing views on builds. Roddie prefers crumple zones and I prefer aeroplanes that will bounce of the ground.

Wow... c'mon Ian... I had 2 gigs this weekend, and I'm tired. I looked forward to coming home to our beloved forum I.S.O. some "Love"

Cribbs74 wrote:It looks to me that the leading edge notches were cut a little deep.

Ron

Ron, That's because the piece of balsa I used was wider than the leading edge on the drawing while I left the ribs the same size. That's also the reason why there is a flat part on top and bottom. The centre sheet of wood should in fact butt against the back of the leading edge with a rounded flare. Because the LE is wider, I glued the centre sheeting on top of the LE and sanded it.



When I bought the wood to make the model in Jan of this year, I was still the unexperienced balsa buyer: as long as the dimensions were ok, that "wood" do for me. Later, by reading other plans and posts, I realised that the LE wood was indeed soft but light. So that's the way it went.

Lieven

Lieven,

I hope you don't think I was criticizing. You did an excellent job with the build. Much better than I can do. I was just trying to figure out why the wood gave way so much.

In reality you hit a tree and even hard balsa would snap given the same scenario. Here's to a quick rebuild!


Ron

No, you weren't criticizing, the grooves are deeper indeed. I think the whole would have been a little stronger if the ribs were properly glued into the grooves, but would that have resisted the tree, no, I don't think so. I just wonder, to avoid such things again, how do you stay on the same spot while turning round and round and round?

Lieven

OVERLORD wrote: I just wonder, to avoid such things again, how do you stay on the same spot while turning round and round and round?

Lieven

Hi Lieven, I used to have to fly 1/2-A in a small side yard. I had about 60 ft. to work with... between the house, a stone wall, shrubs and a tree-line. I measured-in 30 ft. for the center of the circle, where I used the "lid" of a 5 gal. pail with hole drilled through the center to accept a long (8") aluminum gutter nail. Hammer the nail through the lid, into the grass/dirt... and you have a reference point to feel with your foot. It takes a little getting used to at first... but soon becomes second nature. I used 25 ft. lines... and although there "were" times I got a little dizzy, I never hit anything... because I always had a 5 ft. "safe-zone" to work with. Maybe that's a little "tight"... but it worked for me.

If you paint the lid "green"... you can leave it in place and just trim around it when you do your lawn-mowing. That way, it isn't real noticeable... and you don't have to measure-off every time.

Lieven,

The dizzies go away after a while. In your case you had multiple problems as the plane wasn't flying right so you were spinning and fighting at the same time.

Roddie's suggestion about marking the center is a good one. Some use a rag or other things. I use a paver stone as it doesn't move.

Once you stop getting dizzy you don't move much off of center anymore.

Ron

I use a big square piece of white sweatsuit material. It stays put, and after I do a wind dance, I can see it out of my peripheral vision and work back to it. If I can't see it, I know I'm right there.

OK, I'll make myself an artificial spot to use as a reference, and even better, choose a place without trees. Below some pictures of the repairs still going on.

After cleaning the bits out, I shaped the edges of the LE flat and square and glued in a new piece of balsa. I cut out the rib parts, beginning at the spar up to the LE, cut out the holes for the lead outs and glued the ribs in place with brackets on both sides for reinforcement. The broken parts behind the leading edge will be filled in separately.

Lieven

Glad you're fixing her up Lieven... Looks real good!

Roddie

The woodwork is finished. I'm waiting for the Oracover to arrive. I've also cut out a bit of the elevator hinge material as this is rather heavy piano wire. After cutting, I put the pieces on the scale but that indicated 0. It must have some effect, I think.

Lieven

SUPERB Lieven!!! The lap-joint on the l/e must have taken some time. It all looks beautiful!

I like it!

Now cover and fly!!!!

The Jr Satan is repaired and covered. Last time when it came down after hitting the tree, I found that the engine crankcase bolts were loose. I fixed everything and did a test run with the 8x4 prop: all went well. I hope to fly  soon.



Lieven

That Satan is bigger than 1/2A, so probably 52'. I'm looking forward to seeing it fly again. Getting through the launch is the hardest part with those. If it goes straight up, just let it go and back up. It'll probably tighten up and fly.

One thing I would do due to earlier problems. Tape a quarter on the outboard wing tip with clear packing tape and add 1/2Oz. of nose weight. You could always remove these but it will keep down the sensitivity issues until you get used to the plane. Ken

Lieven, now I can see why you and Ken were so interested in my Voodoo. The Jr. Satan is a very similar design.. a little smaller?

My lines are 15 meters I think. I prepared already a 15g, which is near 1/2 oz, and also a 20g weight to fix to the nose. I'll tape some coin on the wingtip too. I also binned my self made handle.

To me, both Satans and the Voodoo are very good looking. I don't know why but they seem to look much better than other combat planes. The Jr Satan has a 29' span. You can find the drawing on Outerzone. That's where I got my plan from:  http://www.outerzone.co.uk/plan_details.asp?ID=1816

I'm gonna give it a try as soon as the weather gets better. We have rain and a lot of Wind at the moment. I hope I can fly across the road instead of my neighbours garden. At least there are no trees that can move into my way. I maybe have to wait until they cut the grass 'cause that's rather high at the moment.



Lieven