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Old Jan 02, 2007, 09:35 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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No Plotter???

It really sucks not having a friend with a plotter. My OFB Chuck has moved to North Carolina, and I'm stuck up here in Clovis. He used to plot stuff for me and help me with drawing problems. The closest graphics house is 100 miles away... ... so I am drawing what I have in cad out on large graph paper... ... Not but one night really wasted, though. I have to go to Albuquerque overnight tomorrow, but the wood chips will fly when I get back. I believe I'll look for a good graphics house while I'm there. Don't worry, I've built over much worse plans than these... I should have the fuselage complete in a week or less. The empennage will take a bit longer. How about ballast tubes under the wings? How about pull-pull controls? Anyone for a V-tail option? Post your opinions on the Yardbird II thread, please...

Jack
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Old Jan 02, 2007, 09:51 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Wood fuselages can be...

... pretty... This one won't really win any beauty contests, but it isn't ugly, either. It's big enough to use standard servos if need be, with just a little more hollowing of the canopy block. I drew it and checked with the servos and battery pack, and a large receiver, so I know everything will fit, no problem. This one has a horizontal keel that forms the servo tray, battery pack area, and the ballast box bottom. I may be old fashioned, but I'm not reverting all the way back to clear canopies... I always got glue on the darned things anyway...
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Old Jan 02, 2007, 10:09 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Lots of sanding on this tail boom...

Of course you can't see it here but the sides will be laminated with cf between the layers. There'll be some triangle stock and the whole thing will get rounded and made pretty. The forward fuselage is plywood. I had plans to glass and paint mine, but I really want to see how strong the stock fuselage will be, so I'll wait for the next one to do that. This one will just get Monokote. I guess when the wings wear out, you can alwauys strip the tail off and use it for a baseball bat, or personal protection, or... Anyhow, the tail details are worked out and the stabilator will be an easy pull-pull with the rudder having the option of being pull-pull or standard pushrod. Here's the preliminary vertical tail drawing. It's not a straight taper, and all the curves are derived from airfoils... fuselage, tail, tips, and all... A little harder to build? Yes. Worth it? If you're a builder... Yes.
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Old Jan 02, 2007, 10:11 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Oops, the rudder is not really cut off flat on the bottom... my printer isn't quite big enough...

Jack
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Old Jan 02, 2007, 10:24 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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One more thing, this fuselage will be eventually made of fiberglass and Kevlar... maybe...
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Old Jan 04, 2007, 09:22 AM
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Aaaala Baaama
Joined Sep 2004
734 Posts
Panel joiner options?

Jack,

Sorry for the intrusion, but can you talk for a minute or two about wing panel joiners? We (Alabama Renegades/NASF) will have some Yardbird wings in the works shortly and are consideing options for panel joining rods. I've seen mention of steel and 7075-T6 in the Yardbird threads, but no mention of carbon rod. I know you cannot fit a large enough carbon rod into the airfoil to equal the strength of carbon steel, but do you know how strong is "strong enough?" Is there a recommendation for carbon rod, or do you consider that a "no go" given the construction of the rest of the wing? Am I looking at the wrong material property? (is carbon too brittle for the application, fracturing rather than yielding?)

Jack, thanks for this awesome design and helping make a competition grade built-up wing achievable by the likes of us Renegades/Silent Flyers! We'll hopefully have a gaggle of Yardbirds later in the year...

Chuck (in Aaaala Baaama)
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Old Jan 04, 2007, 07:01 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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My Joiner

Hi Chuck,

I am using 3/8 aluminum. It's bent 8 degrees, and nests perfectly between the outboard spars. Unfortunately, that means the holes, originally placed for a short, straight joiner, will have to be relocated. The following photos show my joiner in detail, as well as the incidence pins and a couple of hints for beginners for drilling straight and getting it lined up.

The first two pics show my joiner holes relocated. When finished, there'll be no voids around the joiner.
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Old Jan 04, 2007, 07:11 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Incidence pins

I used 1/8 cf rod, rounded on the ends. I felt that they needed to be accurate, and that they needed to go through the box rib at the end of the main panel for strength and solidity. Here's what they look like. The plywood end ribs in the ourboard have to match perfectly. The will need to be angle drilled slightly or they will be so tight as to not come off without a fight, It all needs to have a tight, accurate fit.
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Old Jan 04, 2007, 07:24 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Here's How...

I made a guide for my 12" long, 1/8" drill bit. I taped 1/8 i.d. tubing to my trusty triangle, and propped it up on the table at the wing root, and out toward the end. That makes it square with the rib, and parallel with the spar tube. When I am plugging my wing on, it goes straight in, so these little 1/4" spuds of cf will need to be parallel to that motion for the outboard to plug on properly. The angle won't match the outboard plywood rib, but alll you have to do is insert the drill and move it up slightly. Do it quickly so as not to hog out the hole too much... (Since I was asked by someone from Alabama, I thought I'd put that in terms they'd understand... ) We need to keep the fit very close...
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Old Jan 04, 2007, 07:34 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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When you're done...

,,, it should fit like this...
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Old Jan 04, 2007, 10:01 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Tonight I've made a bit of progress on my fuselage. I thought I'd have enough plywood, but I didn't. Closest hobby shop is 100 miles... My nose section will get 1/8 bass outer sides, because I probably won't be able to find plywood in Clovis. Maybe Hobby Lobby will have it...

Anyhow, I have the aft sides cut and the air-ply inner sides cut. Oddly the air-ply isn't actually quite 1/8 thick. If I do find regular, 5-ply plywood tomorrow, I'll just use the airply pieces for a pattern... No wimpy noses, here... forward bottom sheeting is 1/4 poplar... lots of work, but it will be tough. I have printed my ribs for the horizontal tail. I tapered it from a NACA010 to NACA008. The vertical tail is NACA010 all the way. It's going to be light, and bullet-proof. The only heavy part is going to be the forward fuselage, from about mid wing forward. I had another ureka today on the way home from Albuquerque... Why can't I heve those in the hobby shop parking lot... especially considering how far I am from one? It involves my pull-pull stab and a large aluminum servo output shaft... more on that later...
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Old Jan 05, 2007, 09:23 AM
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Aaaala Baaama
Joined Sep 2004
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It's in the details!

Quote:
Originally Posted by schrederman
Do it quickly so as not to hog out the hole too much... (Since I was asked by someone from Alabama, I thought I'd put that in terms they'd understand... ) We need to keep the fit very close...
Thanks for the details, Jack... and in a language we can understand . Looks very straight-forward!

I appreciate you taking the time to provide the bits and pieces that will help fill in the blanks for us! I am looking VERY forward to starting my "Yawd bawd" wing shortly...

Chuck (in Aaaala Baaama)
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Old Jan 05, 2007, 05:58 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Chuck,

I'm honored that y'all are considering this build. Us Southeren Boys gotta stick together. I was unable to find 1/8 plywood, so I'll be doing my forward fuselage sides in air ply and bass. No matter, as either will be stout enough. I'll continue with the pics and descriptions as they come... our weather is supposed to turn to crap just in time for the weekend. I may get a lot done...

Jack
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Old Jan 05, 2007, 09:43 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Fuselage, the beginning

The sides are the real meat of this fuselage. They are 1/4" thick, but they're laminated to put the cf reinforcement where it belongs - as far our in the diameter as possible. Remember this is a woody fuselage, and who knows, we may make a plug, a mold, and some of that fiberglass stuff one of these days. Anyhow, there are 4 distinct fuselage sides. Remember that we'll make a left and a right out of these 4. For mine, since I can't seem to keep my act together, I am using 1/8 air ply for the inner front sides and 1/8 bass wood for the outer front. The inner sides will but up against the nose bleck, and the outer sides will lap over the sides of the nose block. The carbon fiber is .007 X .25 again and is laminated in between the balsa rear fuselage sides. Here's what it all looks like...
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Old Jan 05, 2007, 09:57 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Different angles

I used scarf splices for the sides to increase the glue area. I also don't like stress points so my angles are different. This keeps it from going from hard to soft in a short area, and keeps the glue lines from being right together.

A word about glue joints. Wood glues work in 2 ways... adhesive and cohesive. They adhere to the wood creatring a molecular bond, and they cohere to themselves within the glue line. The adhesive property is stronger than the cohesive, so the thinner the glue line, the stronger the joint. I preach this often, and do my best to practice it... Something I learned in aircraft wood working class some 37 or 38 years ago... This doesn't necessarily apply to epoxies, so don't take me to task with that one too much...
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