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Old Nov 16, 2013, 08:48 PM
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Build Log
SunBird by Hobby King

The Hobby King SunBird, a blatant ripoff of the Bird of Time, but smaller. And that works great for me, as the original BoT is too large for my local field. I've wanted to build this plane for a while now, but other planes keep getting in the way including building a pair of the Hobby King Red Swans - one is stock and the other which is almost done is a lightweight version just waiting for the covering to arrive. Build thread for Red Swan #1 is HERE and the thread for #2 is HERE.

So I've had the SunBird sitting here for a few months, and now that the weather is usually bad I'm catching up on all of the stuff that has been on hold. General maintenance on a few planes is done, repairs is accomplished on others, so time to build!

To start, I'm going into this build with my eyes wide open. I've built a couple HK balsa kits already and know what to expect: crappy instructions, lack of information on the process, substandard laser-cutting quality, and a plethora of other questions. It's like assembling a car motor based on blog posts by a drunk providing instructions in gibberish.

But that feeling of accomplishment once it's done is addicting! Hell, anybody can assemble an ARF kit, and building a high-quality kit isn't as hard as most would imagine, but these HK kits have their own appeal.

Starting things off, I laid out all the parts to inspect for damage. None visible at all, a good way to begin (and unlike a true HK kit). The quality of the laser cutting was typical and many parts will need tracing with a #11 blade to get the parts loose. Compared to the Red Swan kits the person who did the laser programming did a good job. The areas you need to cut to get the pieces out makes a lot more sense, which is hard to explain unless you build both kits. But take my word for it, this isn't done too bad. I'm not too sure about the wood selection as some of the pieces seem pretty hard/heavy.

As mentioned, the instructions for these kits isn't the best. Actually the instructions suck, which is being kind. Parts aren't labeled and the instructions really don't show how the parts all go together. Typical. There is currently what appears to be a good and comprehensive instruction manual by a fellow builder uploaded on the HK website - hopefully it's accurate as I plan to follow it. It doesn't cover the wing but hopefully will eventually.

As with the Red Swan builds I start the build by cutting all parts out whether I need them or not. Granted this could lead to losing parts but I'll take that chance. Considering the instructions don't help the build process I want to be able to pick any part quickly to test-fit things.

As time permits I'll update this build log to hopefully help others planning to try this kit. I'm sure I'll make mistakes along the way, but that's life.
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Old Nov 17, 2013, 10:51 AM
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Let's get this party started! I'm doing wings first, because I really like how they look, it is what attracted me to this kit and the original Bird of Time. Plus, wings can be a real pain in the ass so I wanted to get it finished first so I could move on to the fuselage.

First step was cutting out all of the ribs. Some came out easy while others needed a bit of persuasion with a #11 blade. But the process wasn't hard to too time consuming. I didn't realize at first that the top and bottom spar caps were plywood, an interesting change from the other kits. I assume this will provide good strength while allowing the kit to use thinner wood than would be possible with balsa. Look at the wing tip rib and how little material is between the top/bottom caps - had the kit included standard balsa caps I doubt the rib would be one piece as it is. Just a guess though...

So once all ribs were cut out I matched them up and made piles of each type. These piles were then divided in half - half for the left wing and half for the right. That told me what I had to work with on each wing. The next step was trying to figure out which ribs went with the outer panel and which were for the inner panel. I used the "instructions" as a rough guide for this. In case I forgot to mention it, the instructions are crap, although the print quality is quite nice and the paper is heavy stock and glossy. Kind of like if Playboy Magazine had a magazine filled with 60 year old women from Siberia. Quality material except for the content. My apologies to any 60 year old women from Siberia who happen to read this. Back to the build. So everything is laid out in a way that makes sense, the only question area is the rib layout on the inner panel at the fuselage, but I'll figure that out when I get there. First thing I'm working on is the outer panel.

See Pic 1.

Along with the ribs and spar caps I also placed all the spar webbing in place, keeping an eye on the order in which they are installed. The webbing is smallest at the tip and gets larger towards the center. In theory, the webbing should also PROPERLY space the ribs out so all the pieces line up for assembly. At least that is the way it would happen in a good quality design. Surprisingly, that isn't what happens here. So in the picture you can see the webbing all held in place with spring clamps ($5.00 at Harbor Freight for a bunch of them, a GREAT deal!). The problem is that almost all of these webbing pieces are too long which keeps the ribs from lining up properly at the leading and trailing edges. Look closely at the thin piece of balsa at the trailing edge of the aileron ribs, how there is a gap at the left and right ends. That gap shouldn't be there and that piece should touch the wingtip rib and the large rib at the left of the picture. The rib webbing needs to be trimmed.

See Pic 2.


Here is a good example of the webbing problem. The web should be the same width at the wing spar as it would be if it were at the leading or trailing edge of the wing. This web is shown at the trailing edge where it is the width of a rib too long. So I simply mark it and cut that excess off. That process is repeated across the length of the wing. It isn't a big deal, but it's irritating that the kit manufacturer didn't bother to do this right. This is the same thing I found on the Red Swan kit.

See Pic 3.


Measuring, marking, and cutting, one pair of webs at a time. Once these are all done I'll cut the webbing for the other wing to make that assembly go faster. I'll also probably modify the webbing a bit by installing it between the top/bottom spar caps instead of in front/behind them. This will remove a bit of extra material and should still leave me with a good strong spar. I'm not 100% positive it's a good idea, but this wing isn't much larger than that of the Red Swan and I think what I've got in mind will be stronger than what I used on that build.

See Pic 4.


By the time I get to the wing tip you can easily see how much material I've removed from the webbing. The aileron will need to be trimmed slightly once the wing is glued up. The wing tip is made from two layers of balsa glued together. Kind of big and blocky, so I may cut a couple holes in it to lighten it up a bit. The dial caliper I'm using to measure the ribs isn't necessary, but it does work nicely for this project. You could get the same results carefully using a ruler or scrap pieces of balsa and a pen.

See Pic 5.


One item of note that again isn't really covered in the manual, there is some dihedral between the inner and outer wing panels. This angle is set by plywood sections which slide in between the spar caps. A couple notes on this... First, you'll want the angle of the rib to match the dihedral angle so when you slide the inner and outer wing sections together the ribs sit flush with each other. Also, to get this plywood joiner in place you need to remove the balsa on the rib between the spar caps. It appears that this only needs to be done on the two end ribs, and that the plywood will end up by the third rib. I'll know for sure as I get a little further in the build. But keep this in mind as you build because trying to remove that balsa from the ribs after everything is glued together so you can slide the joiner in is a pain in the butt (as I found out on the Red Swan). I'll probably glue some of the webbing in place at this part of the wing, then cut the ribs as needed for the joiner to fit, and then finish the webbing. Or something like that. It isn't a huge deal, but figuring it out now is better than waiting.

See Pic 6.
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Old Nov 18, 2013, 05:37 PM
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Did you come up two short on webs?
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Old Nov 18, 2013, 05:41 PM
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As I'm assembling the wing and looking at the rib webbing I'm hating it more and more. Not because it's heavy or wouldn't work properly, but because most of the pieces aren't quite tall enough. They're all too wide as mentioned in the previous post, meaning I had to shorten them, but most are also too short meaning they don't go all the way from the top of the top spar to the bottom of the bottom spar. This isn't a huge issue for strength, but it irritates me. On my Red Swan I had the same issue and it's somewhat visible thru the lightweight covering, so this time I looked at some options.

The idea I settled on was moving the webbing from outside the spars to between them, as shown in the first picture. This involved cutting each piece down a bit. I also cut a third for each area so the webbing would be a solid block between each rib. This may have been overkill, but by doing this I'm keeping about the same amount of balsa between each pair of ribs as would otherwise be there. Plus I think it's just plain cleaner looking this way.

With picture 2 you can see that most of the webbing is now hidden between the top/bottom spars. It feels very strong, stronger than the Red Swan wing I'm going to cover in the next few days. I didn't move the webbing inside on the innermost part of this section of wing. You can see a couple pieces in this picture on the left side of the wing. This is because the plywood which forms the dihedral runs through the space between the spars. I could have skipped using full webs here but I had them cut and wanted that part of the wing to be nice and strong. I also had to get a little creative on the two ribs at the left, as the dihedral plywood runs right through them. I'm cutting them into two pieces and will re-install them as the wing sections go together. I'm not sure if it's the BEST way to do this, but I'm confident it will work regardless of what the instructions do or don't say (mainly don't).
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Old Nov 18, 2013, 05:53 PM
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The same beating I got....
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Old Nov 21, 2013, 08:25 PM
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Now that the Red Swan #2 is done and waiting for a maiden flight I can turn my attention back to the SunBird. The starboard wing's main structure is nearing completion, and it has been trickier than the wing of the Red Swan for sure, but it isn't too bad. The trickiest part has been getting the dihedral plywood installed. I think most people would simply build the center and outer wing sections and then join them together, and that's what I did for this wing half. Now that I've got it mostly done I think it would be better to build the spar with the dihedral first and then add all the pieces to finish it up.

By the way, the instructions are crap so I'm still looking at the far left edge of this wing half (the eventual center of the wing) to see how I want to finish it. I know the center of the wing is going to be sheeted and the ribs are sized to make this work, but a little head-scratching is needed to make sure I don't build it incorrectly.

Pic 1

To do this I glued the two dihedral pieces together and let it dry. Then I came back and glued the top & bottom spars to it, and then clamped it in place. Everything was pushed flat against the bench to make sure it is flat. The ends of the spar will be a little long but are easily trimmed to final length once the wing is completed.

Pic 2

Here you can see the dihedral brace and spar caps secured in place waiting for the glue to dry. I had to cut four ribs to make room for the dihedral brace, and will glue the front ends back in place as progress continues. Gluing them right now would be a waste of time as there isn't any additional structure yet to help secure them. I'll run a length of carbon fiber for the leading edge which will certainly help, as will some webbing used to cover the spar at the dihedral.

Pic 3
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Old Nov 21, 2013, 08:26 PM
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Quote:
Originally Posted by JohnathanSwift View Post
The same beating I got....
Maybe I'm starting to think like the Chinese - this isn't quite as hard as I had expected!
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Old Nov 21, 2013, 08:32 PM
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Confuse Us say, "conclusory instructions mess with Occidentals' heads!"
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Old Nov 23, 2013, 10:13 AM
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I ran across the picture below of a plane similar in design to the SunBird (I don't think it's a real BoT) and I really like the look. I've been waiting for a design that really grabbed me to use some transparent covering and this may be it. The original orange/cream design of the BoT was my first plan for this bird, but a design similar to this has me re-thinking that plan.
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Old Nov 23, 2013, 01:13 PM
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We have gotten spoiled since the days when the best one could hope for, without spending a LOT of money on a premium brand, was dodgy die cutting and lots of shaping things to fit. Since my CA allergy seems to have abated somewhat and I have been tolerating "odorless" CA I have been thinking of a kit for a winter project and the Sunbird is one on my wish list.

I have also always been a big fan of using transparent covering on open structures for better visibility and transparent blue and white is a classic. I am also a big fan of fluorescent trim. Fluorescent orange with blue or purple really appeals to me. I also like using an asymmetrical scheme to help with orientation. I'll include a couple pics that might provide some inspiration.

Cheers!
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Old Nov 23, 2013, 02:03 PM
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Those are some sharp looking planes, thanks for sharing.
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Old Nov 23, 2013, 02:24 PM
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New outfit for the ugly woman.
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Old Nov 23, 2013, 03:00 PM
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Quote:
Originally Posted by JohnathanSwift View Post
New outfit for the ugly woman.
What is your opinion on how it flies?

Also, I just noticed a question you asked a while back about coming up short on a couple pieces of webbing. I came out fine with mine, but I'm doing things way different than the "instructions" show. Instead of webbing in front and behind the spar caps to create a box I'm cutting three smaller pieces and filling in the space between the caps. The wing is about 80% complete now, and all the main sections are glued together and it feels very solid having been done this way. It was a pain cutting all the pieces, but the webbing was just designed in a half-assed manner so I don't feel bad about changing it.
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Old Nov 23, 2013, 03:02 PM
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Flies great!

Replace the carbon push rods with steel.
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Old Nov 23, 2013, 03:42 PM
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Thanks, Joker. They are both ARF's that I dressed up so my old eyes can pick them up better. It's amazing what one can accomplish with the odd bits of covering collected over 45 years or so! I am particularly pleased with the fluorescent yellow I added on the Specter. It really helps me to determine my climb angle and pops out when I deploy the spoilerons.

Cheers!
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