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Old Apr 30, 2013, 07:17 PM
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Build Log
BBCC2- Dallaire Sportster-JohnAV8R

Waiting to the last minute,

this will be my entry.
BBCC2- Dallaire Sportster-JohnAV8R
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Old Apr 30, 2013, 07:18 PM
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BBCC2- Dallaire Sportster

future comments BBCC2- Dallaire Sportster-JohnAV8R
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Old Apr 30, 2013, 07:46 PM
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John! Glad to see another vintage free flight builder in this thing.

And you chose a nice one to build too! Plan build? Short kit?

David
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Old Apr 30, 2013, 08:02 PM
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Bravo! Sub'd. We are building similar sized OTFF ships. Just a stab of a guess - perhaps you might try doculam/tissue for the finish based on the excellent work you have been documenting for the rest of us on your other thread?
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Old May 01, 2013, 05:03 AM
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Cool plane
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Old May 01, 2013, 07:40 AM
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Traverse City, Michigan
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I built one, from a Bob Holman short kit and plans. It's an enjoyable model to fly.
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Old May 01, 2013, 09:12 PM
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Dallaire Sportster

This is a last minute decision, down to the wire, so to speak. This is a 1/2A sized model made from a kit. It was started by my good friend John M (aka Grand Wizard) late last fall after he put his flying models away for the year, and before he became a "snow bird".
He had the fuse framed up , tail feathers and most of each wing half framed up.

I cut the nose off of the fuse and will make a new one, hopefully to contain a small Mills diesel (0.75 cc or about 0.045 ci).

This model will use the tissue over Doculam covering technique/experiment that I have started :

http://www.rcgroups.com/forums/showthread.php?t=1843370

For better or worse, I've lost the beginning pictures of the bare fuse. So to begin, here are the kit box, plans, and lazer balsa outlines.
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Old May 01, 2013, 09:20 PM
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There isn't very much balsa in this model, other than the ribs; it's all stringers. Lazer cutting is crisp and clean.
Balsa is good, all in all, no complaints with the kit.
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Old May 02, 2013, 07:11 AM
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I was surprised at how little balsa was required to build mine, too.
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Old May 02, 2013, 10:34 PM
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Wing build

The majority of each wing panel was framed up. The centre section required the dihedral braces added. Rather than really worry about each wing tip being raised exactly so many inches, I just used the angle of the ply brace and lined up the spar to be parallel with it. Past experience has shown that the more dihedral, the more sensitive the rudder becomes. Really boils down to your choice. Too little and you may loose a little stability.

Note the extra webbing , but grain running with the spar, and glued to the back of the spar. Each section was first cut, then lightly sanded in order to get a very tight fit between ribs. Webbing applied this way is not quite as strong for vertical compression, but does cover up a multitude of sins. A small weight penalty for a large increase in strength.

Looking on from the front LE of the wing you can see the vertical grained webbing sand witched between the spars. This is really the proper way to go, but does require a lot more care and attention to exact depth, otherwise there is either a minor gap between the glue joint and spar, or the spar will not drop down flush with the rib if the webbing is too tall. You may have guessed it; an explanation later on.

John
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Old May 06, 2013, 09:38 PM
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Wing tips

I really don't like flat wing tips on the ends of my wings. When possible I always raise them, at least a little bit. The plans show the wing tip set very close to the middle of the rib. After looking at the flat wing tips for awhile, I decided the best way to deal with them was to cut them off. They just didn't look right.
Laminating 4 pieces of 1/16th strips looked better (to me) and also made for a much stronger tip. The easiest way for me, rather than make hard wood templates for just this one model, was to use card board.
I traced the wing tip outline onto 1/4" card board, measured back in 1/4" and made over sized cut outs which were waxed before using. Next I soaked (in water) the balsa laminating strips to soften them, then laid the damp strips out, applied Weldbond glue to each of them, stacked them up, then bent them around to fit into the cut out in the card board. Added a few pins where required, and let the tips dry over night. When dry, the tops were sanded down making them all flush and even. The tips were removed from the card board, rounded on the edges, cut to the required size and glued onto the wing LE and TE, each tip being slightly raised so they were not flat. Additional spar extensions were added to brace the tip. All very rigid when the glue dried.
The laminated tips were not really required, but they made me feel a little better about this wing.
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Old May 06, 2013, 10:31 PM
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Great explanation and pics. Thanks
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Old May 17, 2013, 10:03 AM
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top spar standing proud

I was not happy with the top spar standing proud. Moral of the story here, is that you should check the webbing for exact height and fit before you glue it all in.
What to do? Pull it all apart and start over? Throw it out? Not for this model; it's made for sport flying, not a thing of beauty, and this problem won't be seen in the air, or affect the flying characteristic very much, if any.

So, after thinking about the problem, I decided the only thing to do was cut and sand down the spar until it was flush with the ribs.
Yes, this did weaken the top spar, so additional webbing, grain running horizontal, was added. The final end result was a slightly stronger wing.

Before starting, the ribs were covered with masking tape for protection. A small razor plane and medium- fine sand paper did most of the work. The top spar is now flush with the ribs. This may not make much of a difference, but at least I feel better about the fit now. I just was not happy with that top spar standing proud.
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Old May 17, 2013, 12:18 PM
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Nice work, John. Looks good. I couldn't have left it that way if it were me, either.

I plan to add a few webs to the center of the Arrow's wing with spars already in place. I'll sandwich them, but they'll be the same thickness as the 1/16" spars, so fitting them flush will be easy.

Good tip on the masking tap. I think I'll do that when I sand the ribs down to the trailing edge.

I also kind of wish I'd seen your post about flat wing tips before I built mine. I think I would have taken the time to pull them up a bit on the Arrow. But having spent a fair bit of time getting a perfect fit on the tip stringers, I'm not inclined to cut them off now.
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Old May 18, 2013, 07:54 AM
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I agree, good tip on the masking tape, hope you don't mind if I burglarize that tip!

conrad
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