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Sig Citabria Build

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Old 12-18-2009, 08:52 AM
  #1  
Starwolf2
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Default Sig Citabria Build

I purchased a Sig Citabria for my father last year as a form of physical therapy to help him exercise his hand after he had an accident with a table saw. I thought he would find it fun to build an R/C airplane after building a very large number of Guillows airplanes throughout his life. Unfortunately, he seems to be intimidated by the term "R/C." Anyway, when he came by to visit and see our newborn daughter, he brought the Citabria for me to go ahead and build myself.

I've searched through the forums for a detailed description of a Sig Citabria build, but failed to find one that provided the level of detail that I wanted. In case you are interested, here is the only Citabria build I've found [link]http://www.rcuniverse.com/forum/m_761826/anchors_761826/mpage_1/key_/anchor/tm.htm#761826[/link]. Maybe I was spoiled by a past thread that I followed while building my first R/C kit, a Sig 4 Star-60. That build thread was posted by KMOT, and is located [link]http://www.rcuniverse.com/forum/m_3886552/anchors_3886552/mpage_1/key_/anchor/tm.htm#3886552[/link]. KMOT's description of his build is incredible! I really learned a lot from it. My modeling skills are far inferior to those of KMOT; nevertheless, I will try to describe my build of the Sig Citabria. I hope that I will also receive feedback from other kit builders throughout this process as their input should help me to create a better plane.

In case you are wondering about my modeling experience, I've built two ARF's (both Sig Kadet Sr's) and a kit of the Sig 4 Star-60. As a kid, I used to build a few balsa airplanes, but never had the patience for the covering.

I started reading the instructions last night. It seems that this build will be very different from the 4-Star! It appears to be a much older style build. I already have a couple of issues that I need to contemplate. First, is the issue of aileron control. The instructions call for bell cranks in the wings and a single servo in the fuselage. The other forums I've seen suggest that the bell cranks be replaced with individual servos. I see pros and cons to this system. The main pro is that the linkage is simpler with two servos. However, I would have to put large holes through each of the ribs in order to feed the servo wires to the receiver. I'm not sure I like that idea as it may weaken the wings. So, I am leaning towards retaining the bell crank system. I'll have to think about that some more. Does anyone out there have opinions on this topic? The second issue I am concerned about is building the fuselage. A builder in another forum stated that it was very easy to warp/twist the fuselage. I figure that I'll have to be very careful when it comes to that step.

One other thing I should mention is that I'm not sure how fast I'll be building this plane as I have several other irons in the fire. Doesn't everyone?? As I already stated, my wife and I have a 6 week old daughter. In addition, I am finishing my basement (almost done with that, just have to case the windows, install the last few ceiling tiles, and do the trim work), and am about to start building a couple of cabinets for my shop. So, let's see how this thing goes....
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Old 12-18-2009, 09:03 AM
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Default RE: Sig Citabria Build

There is nothing wrong with using the bell crank set up. Problems arise from slop developing between the nylon bellcrank and the pushrods which are usually attached with a Z bend. The solution is to use connectors that bolt to the bellcrank. My suggestion is the Dubro ball links. If you opt not to use the bellcrank, making holes in the ribs does not weaken the structure if done properly. The method is to clamp the ribs together sandwiched between some light ply to prevent blowout. Buy a forstner bit, it's the proper way to make that type of hole.
Good luck with the build.
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Old 12-18-2009, 11:12 AM
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Default RE: Sig Citabria Build

Ditto to everything that Allthegoodnamesaretaken said, but you really don't need to do anything special for cutting the holes in the ribs. There is very little stress put on ribs in that direction. You can (and I have) just cut a slot in each rib for the wire and connector to go through.

Here is a pic of an Ultra Sport wing I built a few years ago. The Ultra Sport has solid ribs, but on this particular one, I lightened them. As you can see, there's a LOT of balsa missing yet this caused no problems at all.
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Old 12-18-2009, 12:28 PM
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Starwolf2
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Default RE: Sig Citabria Build

Thanks for the ideas! MinnFlyer, I can't believe how much wood you've removed from that wing. That's really enlightening to know. Groan, I didn't really intend any kind of pun! I think AllTheGoodNamesAreTaken has a good idea with cutting the holes. It would be a great way to ensure they all line up nicely. That way, I could insert a paper tube through the holes as a guide for the servo leads.

I still haven't decided which way to go, I'll probably wait to see how the wing comes along.
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Old 12-18-2009, 12:53 PM
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Default RE: Sig Citabria Build

To me, the paper tube thing isn't really worth the hassle.

Tie a nut or bolt to a string, stand the wing on its root, drop the nut through the servo opening and shake it down through the rib holes. It only takes a few seconds longer than having it drop through a tube and it saves you the hassle of INSTALLING a tube!
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Old 12-18-2009, 04:06 PM
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Default RE: Sig Citabria Build

I built the Sig Citabria a while back. I mounted 2 servos in the wing. For me, the most difficult part was aligning the fuselage so it was straight. All in all, not too difficult if you take your time. Also, I covered mine with Solartex. Attached is a pic.
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Old 12-19-2009, 04:00 PM
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Starwolf2
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Default RE: Sig Citabria Build

DaveB,
That's a mighty fine looking plane you've built! I especially like the job you did cutting the cowling around the engine and muffler.

My father is still here visiting, so I've recruited him to help get this thing started! At this moment, I'm cutting out the ribs from the sheets and preparing to sand them. I can unequivocally state that I prefer laser cut parts! The next step will be to sand all of the ribs so that they match correctly. Hopefully, we can get through that part today
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Old 12-22-2009, 03:27 PM
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Starwolf2
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Default RE: Sig Citabria Build

So, we removed the rough spots off the ribs, without sanding them flush, just like the instructions stated.

The next job was to taper the front and rear internal wing spars. But first, we had to locate the correct spars. The kit contains 2 pieces of balsa for each of the spar types. Each piece is 36 inches long. When sanding the ribs, I had to cut 4 inches off one of the front and rear spars to help in smoothing the ribs. The confusing part came when I tried to align the shortened (32 inch spars) with the plan. The plan does not clearly denote when the spars end, in fact, it makes it appear that the spars extend to the center section of the wing. Therefore, I used the 2 remaining 36 inch spars during the tapering process. I can always shorten them later if they are too long. Once I picked the spars, the tapering went smoothly.

Next, I pin the trailing edge and the bottom wing spars to the plans. Then, I slid the internal wing spars through the ribs, aligned each rib to the plans and pinned the whole assembly down. I glued the ribs to the internal spars and the trailing edge. Now, I must wait for it all to dry!


I'll enter the pictures in a bit!
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Old 12-22-2009, 03:49 PM
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Starwolf2
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Default RE: Sig Citabria Build

Here are the ribs and spars pinned down to the building board. The last picture shows the spars hanging out into what should become the center section.
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Old 12-22-2009, 09:09 PM
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Default RE: Sig Citabria Build

I have been eyeing a Sig kit for a long time, but had to move and now I don't have the space for building. But, I do with you the best of luck. I'll be watching this thread.

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Old 12-24-2009, 10:09 AM
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Starwolf2
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Default RE: Sig Citabria Build

I can relate to that! Over the past few years, I've moved from my home in Minnesota to Virginia, Kentucky, and 2 different places in Tennessee! Hopefully, things are a bit more stable now!
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Old 01-17-2010, 05:21 PM
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Default RE: Sig Citabria Build

About a week ago, I had a few minutes to work on this thing again. I installed the gussets to reinforce the wing and then I cut off the top wingspar, beveled it and glued in into place at the wingtip. The whole thing went well, but I would've preferred not to have had to cut off the wingspar. It would've been nice if the instructions would've told me it only went up to the last rib instead of the wingtip.

Anyway, here are a two pics.
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Old 01-17-2010, 05:27 PM
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Starwolf2
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Default RE: Sig Citabria Build

Today I beveled the leading edge of the aileron, that was a bit tricky. I had a nice long sanding block and propped up the leading edge as instructed, but the whole thing wanted to keep sliding around on the work table. I finally got it done.

Next up on the list of tasks was the installation of the aileron ribs. The instructions said that a little bit of trimming was necessary to make them fit well. Actually, what they should've said was that every rib need to be beveled at the leading and trailing edges!

The next step is to glue the trailing edge sheet to the top of the wings. It looks like I'll have to do a bit of sanding first to make it fit better on top of all the ribs.

Here's how it looks now.
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Old 01-18-2010, 12:18 AM
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Default RE: Sig Citabria Build

Keep it coming, Starwolf. I'm glad to see that your moving situation has stabilized, and you're able to focus on a builder's kit like this. Indeed, this one looks like a lot of work!

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Old 01-19-2010, 07:54 AM
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Starwolf2
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Default RE: Sig Citabria Build

NorfolkSouthern,

Which Sig kit are you eying? This is my second kit from Sig. I've enjoyed them both (granted I haven't made much headway on this one yet!). My other kit was a 4-star 60. It was very easy to put together, an excellent beginners kit for me. The Citabria kit is a bit more difficult. I'm very glad that I didn't pick it as my first kit!
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Old 03-10-2010, 08:38 AM
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Default RE: Sig Citabria Build

I finally got the first wing off the building board! It needs a bit of sanding yet, but it actually looks like a wing now. I tapered the ends of the internal spars for the other wing. Since I'm supposed to be on Spring Break this week, I hope to spend some time this evening on the wing.

After reading the helpful comments that were posted here, I've decided not to install servos in the wings. I have 2 reasons for proceeding in this fashion. First, I'm told that the bell crank system works fine. Second, I'd like to try something different! All of the models I've put together have a servo in each wing and I thought I might learn something interesting by building the bell crank.

I've attached a picture of the completed wing-tip.
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Old 03-10-2010, 10:03 AM
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Default RE: Sig Citabria Build

Not to worry. I have found that the bellcrank linkage works just fine if you build it correctly.
For incouragment, I have attached pics of my newly completed Citabria. I think three months of benchwork have paid off nicely.
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Old 03-10-2010, 10:17 AM
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Starwolf2
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Default RE: Sig Citabria Build

Senrak, your citabria looks sweet! And only in 3 months! It took me almost that much time just to get the first wing off the building board! If only there was more time in each day! What size engine did you decide to go with? Is that a fuel port on the left side of the cowling? If so, what kind is it and do you like it?
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Old 03-10-2010, 11:08 AM
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Default RE: Sig Citabria Build

That's 3 months of almost full time. 6-8 hour days. I have a lot of free time.
The engine is an O.S. 52 Surpass. It should fly it very scale like.
The fuel dot is a Hanger 9 item (HAN115), but without the tee. Works good anytime you have an enclosed engine. Here is a post that shows a similar setup.
http://rcudev.rcuniverse.com/forum/m...tm.htm#7716092
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Old 03-11-2010, 10:39 AM
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Default RE: Sig Citabria Build

I got to work on the airplane two nights in a row!!!

While working on the wing I've noticed something that has me scratching my head. The trailing edges sit on the top and bottom of the ribs. This raises the surface of the wing by 1/16th inch. If I remember correctly, on my 4-star 60 the ribs were notched so the trailing edges were flush with the top of the wing. I quickly looked through the manual and didn't see anything about sanding the trailing edges to make them flush with the rib. Has anyone else noticed this?
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Old 03-11-2010, 12:10 PM
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Default RE: Sig Citabria Build

Starwolf, You should have some cap strips that glue on the ribs, top and bottom, to even the ribs up with the trailing edges. Also, I might suggest that if you really want to go with the bellcrank setup, you consider pre-routing the wing for single servo per aileron setup just in case you change your mind. I built mine with bellcranks and changed over(after a crash). The surgery involved was a bit painful. Just my .02 Nice build
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Old 03-11-2010, 01:03 PM
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Default RE: Sig Citabria Build

Here is my sig Citabria, my dad modled it after a full size one that he use to own. It was built quite a while ago and flies with an old Super Tiger 46. It also was built with a single servo in the wing and I have found nothing wrong with that.
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Old 03-11-2010, 05:48 PM
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Default RE: Sig Citabria Build

The fourstar did not use capstrips. This is the case with many quick builds. There is nothing wrong with either method. The cap strips do offer a stronger rib assembly in that the method produces a type of I-beam in the rib. It also gives a little better support for the covering. You do not want to omit the capstrips, as they are needed to bring the ribs up to the heigth of the leading and trailing egdes, top and bottom. Study the plans carefully and you will see them drawn on the plans.
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Old 03-12-2010, 08:34 AM
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Default RE: Sig Citabria Build

Capstrips, that's something new to me. I'll look further ahead in the plans as you suggest, previously, I just skimmed through the manual. Thanks Senrak and yel914, I appreciate your advice on this topic.

DavidGeorge212, your plane looks like it was built yesterday! I wish my 4* 60 was holding up as well as your Citabria! []

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Old 03-12-2010, 09:23 AM
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Default RE: Sig Citabria Build

It is all shown on the drawings you are working over.
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