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May 23, 2016, 04:03 PM
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Build Log

SIG Four Star 20 EP


My kit came in the mail last Thursday, so I got just a little time this weekend to work on it. So far i have framed most of the left wing.
This is the smallest of the four star models SIG makes, and should make good use of the several 3s 2200mah packs I already have. I'm hoping it will be similar to the plane I lost a few weeks ago, Thing 1, but perhaps lighter and a bit more capable aerobatically. I have a few rolls of bright red covering, which I will be using for this plane. I'm planning on doing all red with checkerboard black/yellow wing tips and rudder. I'm hoping that will show up well enough in the air for me to tell up from down :-)
I have some new slightly oversize wheels on the way, and a full set of Hobbyking/Turnigy running gear set aside. Basic stuff, but reliable enough I think.

Photos to come!
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May 25, 2016, 02:28 AM
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progress so far


Over the weekend I built the framing for the left wing, last night the right, and tonight I've finished the right wing, and joined them. Took just a little sanding of the dihedral brace to eliminate the tiny gap, and now everything fits satisfying tightly :-)
Once that epoxy has set up tomorrow I can sheet the bottom and install the dowel in the leading edge, the bolt plate in the trailing, and get on to the fuselage next. In reading some of the build threads for this kit i have adopted one mod so far. I installed extra wedges of 3/16" balsa scrap sistering the center wing ribs at the trailing edge, to reinforce where the bolt will go through.

I'm not really intending to make many real functional mods (adding a top battery hatch is popular on this model for example) but I am keen to add any suggested reinforcements from other builders. The landing gear mount point, and the fuselage just behind the wing are commonly suggested place to add reinforcement, and i intend to do that in both places.

I think I mentioned before though, I am strongly considering increasing the size of the rudder a bit, and perhaps adding a stronger point to the bottom edge of it, like the rudder on an edge, extra, or sbach might look.

Anyways its very exciting to be able to make such quick progress on the framing. The Instructions really are quite clear, especially by comparison to those in the hobbyking kit i tried to do before this. This is the 3rd plane I've set out to build from a kit. The first was a miss stick, which was simply so labor intensive I kind of gave up once it became clear I was not only not making much progress, but that much of what I'd built had become warped by humidity in my garage. The second was a hobbyking cub kit, which it turned out was extremely poorly designed, had nearly indecipherable instructions, and was half mis-cut. This is much easier than those so far, and I'm really enjoying it.

Definitely more suitable for a beginning builder like me to spend a little extra and get a better quality kit, particularly for the vastly better instructions!
May 25, 2016, 08:43 AM
T-Squared
Looking great so far - please keep the updates coming.
May 27, 2016, 03:24 PM
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the leading edge dowel, and the trailing edge bolt plate are fitted, and now begins the sanding :-p
Last night I made a redneck bar sander with some scrap wood and glue, so this weekend I can try to get the wing sanded to shape and smoothed.
May 30, 2016, 11:10 PM
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this weekend, sanding, sanding, and more #&**$*% sanding. I've got the leading edges evenly round, and the trailing edges are almost there. I've gotta putty and smooth all the butt joins in the sheeting, did part of the bottom side, but still more sanding. Still need to round off the aileron trailing edged, chamfer the leading edges, etc...
Sanding. Sanding as far as the eye can see.

So far I've been doing it all by hand, having been warned that balsa reacts to power sanding by essentially going away completely. I'm quite tired of this though, and very eager to find some way to speed this up, as it's taking forever. There must be some better technique than this.

With the droids i was always working with hardwood, birch ply mostly and I knew how much time and pressure to use with the power sander. I'd have to try some practice pieces and get used to how balsa sands if i wanted to try the belt sander with balsa. The density fo balsa also varies a lot, so that could be an issue.
I do have an incomplete wing from a hobby king kit I probably wont be continuing with though, so perhaps I could practice with that.

EDIT:
looking at youtube videos of people sanding balsa, i must just be using lousy sandpaper. This guy was taking like 1/4" chamfers off of a block of balsa with 60 grit in 2 strokes. I've gotta be doing this wrong. Guess I'll have to try and stop by a Home depot or whatever and get some good quality paper. The stuff I've been using was a value pack from harbor freight. Guess I got what i paid for...
Last edited by buhatkj; May 31, 2016 at 12:04 AM.
May 31, 2016, 11:38 PM
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Tailfeathers


Tonight I was working on the various tail surfaces. These were all the simple sort of "pin down some flat parts and glue" variety, nothing complex here. Once dry there will be yet more chamfering to do though :-p
I think what I wanna make is take a 12"x24" or so board, and glue a few sheets of good sandpaper to it, and make a sanding board.
Then i can hold the part that needs chamfering at an angle and sort of scrape it across evenly. A few less beat up sanding sponges for rounding off things would be useful too.
Rounded off the trailing edges of the ailerons, and i think i have the wing trailing edges smooth enough. I applied more wood filler to the sheeting joins, that will need more sanding later too.

I noticed when building the tail that the trailing edge of the fin goes all the way down into the fuselage, forming a part of the tail block. This is wise as it strengthens the fin a lot, and I recall reading in a build thread from a few years back that people were concerned because it apparently wasn't built this way before. Good to see either they were mistaken, or SIG updated the kit to include this mod.

For now I've built the stock rudder. Once it's dry and I've unpinned it i can see if I have enough of, and the right sizes of scrap left to build a larger modified rudder as well :-)
Last edited by buhatkj; May 31, 2016 at 11:46 PM.
Jun 01, 2016, 09:34 PM
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Modified rudder


I built a larger rudder using some scrap wood left over from the laser cutter. I just kinda winged it :-p
It looks like it has maybe 30% or 40% more area, and a pronounced point at the bottom, which I hope would minimize any roll coupling it might add. Maybe this will help my 4 star do a better knife edge, as the stock rudder apparently isn't quite up to it.
I'll cover both of them, then probably install the modified one, and if it stinks, I can always cut it off and put the stock one on I guess :-)

The custom one is on the left, stock on the right.
Jun 02, 2016, 08:10 AM
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Quote:
Originally Posted by buhatkj
I built a larger rudder using some scrap wood left over from the laser cutter. I just kinda winged it :-p
It looks like it has maybe 30% or 40% more area, and a pronounced point at the bottom, which I hope would minimize any roll coupling it might add. Maybe this will help my 4 star do a better knife edge, as the stock rudder apparently isn't quite up to it.
I'll cover both of them, then probably install the modified one, and if it stinks, I can always cut it off and put the stock one on I guess :-)

The custom one is on the left, stock on the right.
Good job ! It thrills me to see someone who still loves and has the skills and patience to scratch-build these days. 70% of the fun of the hobby to me ! Look forward to seeing more.
Doc
Jun 04, 2016, 06:41 PM
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I've built most of the fuselage in the last few days. I still need to install the turtle deck stringers but the formers for them are still drying. I use wood glue wherever I can, but ca where the instructions specify it. same with epoxy.
Still not satisfied with the wing sheeting after a lot of sanding, wood filler isn't sanding smooth enough. Gonna try spackle. I was avoiding it cuz it's heavy but I want this smooth if I can.
I've added some reinforcement to the formers that hold the wings on, and the landing gear using some of the scrap wood.





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Jun 05, 2016, 12:59 AM
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Got some more done today, got those turtle deck stringers on, sheeted the front deck, trimmed the canopy, and painted a pilot figurine i'd made on my 3d printer last week.
Close up, it is certainly evident that i'm no real artist, nonetheless it turned out as nice as i could have hoped, and from the 4 or 6 feet away you would look at the plane, she looks pretty good i think.
Jun 05, 2016, 06:30 AM
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About three beers and I'll take her home.
Jun 05, 2016, 01:43 PM
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Interesting use of a 3D printer. Saved yourself some money doing that, so good job. Assuming that silver thing over her eyes is a set of mirror sunglasses?
Jun 05, 2016, 04:09 PM
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Originally Posted by Four Fresh Tires
Interesting use of a 3D printer. Saved yourself some money doing that, so good job. Assuming that silver thing over her eyes is a set of mirror sunglasses?
Heh yeh that's exactly what that's supposed to be. I had a limited number of colors, since I was using my wife's decopage paints. Those are the $.50/bottle acrylics from walmart :-p
I had to mix my own colors for the flesh tone and the hair. In the end very affordable, paints we already had, like 12g of PLA filament on the printer, and a few hours printing and painting. The work was its own reward really, it would look better and be more practical to buy a pilot figurine, but this way i can say i made it from scratch, and it's somehow more special to me.

Also got to sit there and do crafts with my wife for a few hours, a nice way to spend some time together. More fun than TV :-)
Jun 05, 2016, 05:57 PM
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Bravo! Ton of respect for folks who get in the details like this. Great hearing about how it created an opportunity to make it a family deal too.

I'm with you. Where I work on my planes, there ain't no TV to be found. Prefer it that way.
Jun 06, 2016, 01:22 AM
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Up a bit too late, but the four star is ready for covering and final assembly!


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