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Author Topic: Build log: 1934 Competition HLG  (Read 1204 times)
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Yardbird
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« on: January 30, 2009, 08:30:33 PM »

This is my first ever balsa project! Recently, I made a few laminated paper gliders, replete with airfoil, which worked surprisingly well. Obviously, I found them to be a little less than durable, and could only achieve decent performance down hill (they crumple if thrown hard). They tended to work nicely until the moisture made them lose shape and performance, but thankfully they stoked me to the point of no return! I needed a real glider... .

I built my 1934 Competition HLG from plans - http://www.theplanpage.com/How%20To%20Articles/Fundamentals%20of%20Model%20Airplane%20Building/Part%203/Part%203.htm.
It was originally from the pages of "Universal Model Airplane News". I utilized whatever wood I could find, which in the end is decent enough, but probably a little heavier than optimal (c of g is fairly aft). The model (see plans) is all balsa, 1/4" fuse, 1/8" flat bottom 2 piece sweptback wing with 2 1/4" dihedral, and 1/16" tail feathers. As this was my first build, my journey began with lots of research and plenty of un-answered questions which I had to figure out for myself. That is what it's all about, right? All in all it has turned out fairly well.

The fuse was quite straightforward for a first build, laid out on paper partially with the aid of 1/4"sq graph paper, traced on to the wood with carbon paper, rough cut, sand papered to shape. Because I knew nothing of the details involved prior to beginning this project, the coarsest paper I used was 280, so I added some extra work there. Towards the end of the outline shaping I realized that maybe somehow this could all be easier? Again, more research on the matter. I decided to go with a "Stanley 12-101" micro plane for the remainder of the build, which was only airfoil shaping at this point. I love the little Stanley. I think I'm a plane man now. Probably won't need much more than 280 from here on in, we shall see.

The tail feathers were no problem tracing, cutting and shaping. Nothing to report on that front.

The wing was a little more challenging for me, lots of variables to which I knew not how to react. I can say that I was amazed how my less than perfect traced outline of the wing shapes magically turned out nicely curved and symmetric to each other. Makes sense in retrospect as the shaping process through sanding can generally be nothing less than smooth lines, as opposed to right angles and the like, from pencils and razor blades. The profiling of the airfoil was a complete unknown to me as I began in earnest beyond the "make or break" point. As a pilot by profession, I know first hand how critical airfoil shape can be when it comes to functioning within design parameters. It doesn't take much ice on a Caravan wing or a King-Air's laminar flow wing, to increase stall speed exponentially. For my glider's wing, I did some more reading. It was at this point that I made a run to the local hardware store for Stanley (my new little pal Wink). As per advice from the experts, I marked the mid chord (or high point) and masked it, then began planing. As I worked, I checked the general shape with a template I made from the plans. I sanded between runs with the plane, and re-checked everything. On the second wing half, I constantly checked it's shape against the first. Eventually, they both actually turned out well Roll Eyes To achieve the required 2 1/4" dihedral, I made a little 4 1/2" high stand for the wingtip to rest on while I glued the two halves together. I had intended to use some liquid cement for the glue party, but ended up using thin CA and kicker (because I'm too impatient to wait for glue to dry). Wings were now sorted, Fuse - sorted, Tailfeathers - sorted. Time to put it all togethor Smiley

For the wing to seat nicely I had to work a groove into the wing seat on the top of the fuse. That was a hack job at best, but I achieved a good enough result, so no worries. Any ideas for the next one? I continued to use thin CA and kicker, everything glued up nice and square (in future builds, I will def use some Med CA though). So far so good. Check the pics, and look to "Part 2" for the slight hiccup which threatened to destroy my beautiful balsa creation's carefully sculpted lines and its performance potential...
Attached files Thumbnail(s):
Build log: 1934 Competition HLG
Build log: 1934 Competition HLG
Build log: 1934 Competition HLG
Build log: 1934 Competition HLG
Build log: 1934 Competition HLG
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Yardbird
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« Reply #1 on: January 30, 2009, 08:49:22 PM »

So, all is well, right? Ready for a successful maiden flight? Smiley Not quite Sad

As it turns out, I misread the plans ever so slightly and added an extra 1/2" length to the tailboom. Doh! To be certain, I was a little upset at my error. The glider had so far turned out quite well for my first attempt, then I had gone ahead and sewered myself! Oh the horror! I knew I was going to have to cut it Undecided

I asked around, it was mostly suggested that I remedy the cg issue with weight on the nose. However, the cg was too far aft and too much weight would be required for my hand sculpted wings to perform as they should. So I cut her. Then I removed 1/2" or so of material, and CA'd the bird back togethor. I suspect it could never be as square as it was, but it's close enough. I then removed a bunch of material tapering the front half of the tailboom down to the rear portion. My overall reasoning for this operation was that if I cut near the tailfeathers, the material I would have to remove while re-tapering (as well as the 1/2" I sanded out), would help the c of g enough to bring it fwd where it should rightfully be.

Well, it's still tail heavy, but much better. I performed a brief test glide, just to see where I was at before finishing her off and laying on some Varathane. She flies Smiley! A full battery of tests will be performed at the next available opportunity, just after the spray-on "Flecto Diamond Finish" dries and I have sanded her smooth. Stay tuned! Comments welcome, please Grin
Attached files Thumbnail(s):
Re: Build log: 1934 Competition HLG
Re: Build log: 1934 Competition HLG
Re: Build log: 1934 Competition HLG
Re: Build log: 1934 Competition HLG
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Black Arrow
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« Reply #2 on: February 01, 2009, 12:10:30 AM »

Not trying to be critical here but I'm not sure I would rely on CA for the wing joint. A lot of stress comes on that area. Especially when she comes down hard nose first. While I realize it's already done and you most likely are not willing to take it apart, what you can do is lay a 3/4 inch wide strip of very fine fiberglass over the joint and then rub a very thin coat of epoxy into the glass. Even a strong regular fabric like nylon would probably work. You could even use other types of glue but epoxy is my choice for wing joints on HLG's. Yes, the epoxy adds a tiny bit of weight but it does so at a critcal area.
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Sundance12
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« Reply #3 on: February 06, 2009, 06:14:51 AM »

Hi Yardbird, congrats on completing your first ever Balsa Project, from the pictures it looks very nice. The fact that you caught a critical error was important and must not be viewed as any kind of major setback. Just ask any of the guys on this forum how many of them have made two left or right fuselage sides to a model instead of one right and one left.

I like you first attempt and it will fly great.

Sundance12

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« Reply #4 on: February 09, 2009, 07:14:27 PM »

yardbird

I have more than 40 years building model planes and I still make two of the same parts for a plane sometimes!!

George
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Yardbird
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« Reply #5 on: February 22, 2009, 01:56:49 AM »

Just to update my project, the maiden was a total disaster! Just kidding Tongue I enjoyed some minor success, it was far too windy for my bird (eager, couldn't wait), but it flew pretty good overall. Had some great downwind flights actually. On about the 15th toss, she self destructed on release. Came completely apart Shocked. Funny thing was that the CA'd wing/fuse joint wasn't the prob, the balsa split below the glue joint. Some light glass would have been welcomed in that instance. After chop shopping the tail during the build, I felt a wee foolish about having done so, and sure to shiny nickels it flew apart more than once that day (CA'd her back on for round 2 before total destruction ended the day's activities).

So, was it worth it? Damn straight! Learned alot. Enjoyed the process. It has since propelled me into all sorts of projects. I am fully hooked. Specifically I have had great success with a bunch of Chuck Markos' mini CLG's. Good times! Easy! Trimming out those little rockets was certainly much easier because of the '34 build and attendant research. I have also started a mosquito class SAL project for my PZ Vapor brick's new home (currently resides in a Liddlebug) and will be starting a DL50 DLG soon (just flew a friends, love it!). As far as FF, I have my eye on building a Pelicatoo and making it CLG. I look forward to that.

For all the advice, I thank you Wink If I'm ever stuck, I know there are answers to be found here. Cheers!
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hermit
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« Reply #6 on: February 22, 2009, 08:42:15 AM »

Sounds like you've got the bug alright. I enjoyed reading of your day at the field, good luck with the upcoming projects.

Doug
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« Reply #7 on: April 29, 2009, 07:53:35 PM »

Now don't be a stranger and show us some more of your planes as you build them !!

George
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« Reply #8 on: April 29, 2009, 10:09:40 PM »

Hey Yardbird...nice build and keep up the ff spirit we need all the enthusiasts we can get. Hey if you feel like it we will try to have a free flight championships in Calgary this year or next....you might wanna start getting some gliders ready eh? Wink

B
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probligo
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« Reply #9 on: May 16, 2009, 03:25:27 PM »

Blackarrow,

I have often used CA for the wing joint, and in general your caution would be correct.

However, if you take the first few mms of the wing te shaping out with a carpenters rasp and save the fibre it makes an excellent reinforcement for the joint.

Use slow CA, and attach the wing. Leave for 24 hours to cure. Put on a pair of latex gloves. Run a thick bead of slow CA down the joint, Cover with the wood fibre and then quickly run your finger through the mess to create a shaped joint between fuse and wing. I started doing this by packing the wood fibre into the side of the joint and then dripping fast CA into the wood fibre. It works, but the results can be pretty hairy and difficult to smooth out.
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Hepcat
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« Reply #10 on: May 17, 2009, 07:37:12 AM »

Yardbird
There is no need to castigate yourself for the damage suffered by your HLG on its early flights. There have been many bad design features in model aircraft over the years and what is surprising is that so many of them have been perpetuated instead of being eliminated. The 1934 HLG is certainly a prime example; the fuselage has a section that protrudes above the main fuselage outline and onto which the wing is mounted. (This is clearly seen in the illustrations in your first post.) Any impact which creates loads between wing and fuselage (or fuselage /wing, depending which hits first!) will try to break this ‘neck’ of wood along the grain somewhere between the wing joint and the main fuselage outline.

This is presumably what happened to your glider – not your fault at all, just bad structural design. Pick a better design next time and have fun.
John
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Yardbird
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« Reply #11 on: July 23, 2009, 01:18:47 PM »

Indeed the design was a poor one, but it looked good for my first! Still does, looking at it, nice lines.

I have since cobbled together a great many ships and learned much. I am finding that its a nice break from RC slopers and DLG's to just bash out a simple FF model. To contribute to this fine community and to the betterment of design in general, I plan to release a balsa scratch design soon that will have none of the shortcomings inherent in the old '34 Smiley Simple solid sanded wing, light CF boom, no timer (yikes!).

Thanks for all the help earlier.
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