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Old Dec 06, 2012, 08:26 PM
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United States, MD, Lutherville-Timonium
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Wings continued

The wings are generally built. They still need the radius sheet pieces, final shaping and sanding and the joiner adapter needs to be matched to the root ribs. The dihedral breaks worked out really well, though I still could have gotten the joint more perfectly tight. It's good, though, they match with 7 angle giving 3.5" rise at the tip end of the outer panel per Ray's calculation. And the joints are strong. The tips are rough carved. I still need some finish shaping and sanding on them as well.

The spoilers are cut but still need to be installed. I'm putting HS-55 servos in each spoiler bay and using a coupled channel pair in my radio programming. Each wing half, without joiner rod, adapter, or servo, weighs in at just a hair above 11 oz. before sanding begins. I think I will meet my 25 oz. wing goal with all the parts attached and the wings covered. That should bring the plane in at about 55 oz. AUW.

W
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Old Dec 06, 2012, 08:33 PM
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Nice work Wingloada, you gonna cap stip the ribs?
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Old Dec 06, 2012, 08:40 PM
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Thanks IHAVAWDY,

I will sand the tops of the wing panels flush and leave it at that. There's no indication on the plan that the ribs need cap stripping so I'll go with the design. The TE height needs to be sanded down flush as the TE stock is thicker than the airfoil at that part of the section. With that the tops should be nice and smooth.
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Old Dec 06, 2012, 08:55 PM
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The wing joiner tubes are both potted and aligned using Jack's instructions for laying them flat and straight while the cabosil-epoxy sets. It worked perfectly. I have noticed, though, that once the epoxy sets, that the aluminum joiner rod, which fit the brass tube perfectly before the tube was installed, now doesn't go in smoothly and is very tight on both wings. I was extremely careful to keep epoxy off the rod and out of the tube so that's not it. Does epoxy expand while curing causing the brass tubes to slightly shrink in diameter? I'll take off a bit more material on the joiner rod making the fit tightly but not too tightly so the wings won't get stuck on the joiner rods. With this wingspan and my car, that would result in me having to live there after at the flying field. Better put a tent and sleeping bag in my trunk.

W
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Old Dec 06, 2012, 09:17 PM
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I wouldn't blame the brass from shrinking as much as the aluminum growing- a couple tenths- .0002" is enough to do what you mention. if in search of a reasonable understanding of a tolerance, I was told by one boss- a gunsmith for a major county here in twin cities, that a .0003 tolerance is the average for a bullet in a round gun- to give you an accurate 'hands on' idea.
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Old Dec 06, 2012, 09:34 PM
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I think that's right because I ran the aluminum under cold water for about a minute, dried it off well and then it slipped right into the tubes. The aluminum changes dimension even if I twist it in my hand for a few minutes (like when twisting, tugging, and sweating to pull the stuck rod out of the wing when finding, to my surprise, that it didn't go in easily anymore... ) . I need to take the rod diameter down a little.
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Old Dec 06, 2012, 09:55 PM
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United States, MD, Lutherville-Timonium
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Airplane parts

Soon these will be joined.

I planned to use 10-32 nylon bolts for the wing mounting to the fuselage, which has steel nuts embedded in F3 and F4. I have also seen people use a steel 10-32 bolt in the front mount and a nylon bolt in the rear with the idea that a wing strike will rotate on the steel bolt but sheer the nylon bolt and the steel front bolt is stronger for wing security.

Those of you with more experience than I, will two 10-32 nylon bolts be sufficiently strong for the wing-fuse connection?

W
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Old Dec 07, 2012, 09:22 AM
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Wing Loada,

Ok,
1. main panel halves have 3.5* angles on the root rib and tip rib?
2. outer panel root rib has 3.5* angle
3. outer panel tip rib and tip panel inner rib are set at 17.5* to arrive at 35* total?

Am I reading the plan correctly?

3.5* main panel 3.5* 3.5* outer panel 17.5* 17.5* tip
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Old Dec 07, 2012, 09:54 AM
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Yes, I think, (I don't have the plans here) but I used 15 for each winglet tip so it results in 30 at the winglet joint. I thought that's what the plan said but I could be wrong. I doubt it will matter much if I am 5 off for the 6" tips ... I hope.

W
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Old Dec 07, 2012, 04:18 PM
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United States, TX, Weatherford
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Those angles mentioned are correct. However, on my last one, and on all the ones I will build in the future, I'll decrease the center dihedral to 2.5 degrees on each side for a total of 5 degrees in the center. The winglets were originally set for 35 degrees, but the 5 degrees missing will not hurt. I would not go less than that...

That's a NICE looking model so far... however, I can't see it that well in digital pictures... Perhaps you should send it to me for final inspection... (I've been trying that line for about 8 years on lots of Hawk builders, and it hasn't worked yet... )

Darth Disappointed...

PS... Got the power done for the new man cave today before coming to work. The upper shelves will go in Sunday, as I have to work tomorrow... A few more home improvement projects in the works, but nothing major... and then I start... BUILDING!!!
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Old Dec 07, 2012, 05:00 PM
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Quote:
Perhaps you should send it to me for final inspection...
I'm not sure I can do that, Jack... Let me see if the post office has 12' x 3' padded mailing envelopes. If so, I think I can stuff it in there since the stab detaches. Yeah, I've noticed you using that ploy in past posts. I am delighted you think it's worth trying to whisk away from me!

More photos as I go. I feel close to completion, but the last 10% usually takes half the time of the build, right? Plus, winter has arrived...

I'm going to build the convertible electric/glider pod with a Mountain Models Bubble Dancer boom next to see about that option for the Hawk wing and tail too. That should get me to the new year. Then it's just a four month wait until spring here in the Mid-Atlantic.

Bill
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Old Dec 07, 2012, 05:20 PM
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United States, MD, Lutherville-Timonium
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Spoiler linkage

I've been thinking about spoiler linkage options. I have to admit that I feel a bit geometrically challenged in terms of drawing the linkage for a servo-driven spoiler that will work smoothly through its entire throw. I have read a lot on these groups and I am leaning toward a servo that pushes up the spoiler with a free servo arm with a rubber band that returns it to flat with small magnets and pieces of x-acto blade for the magnets (one at each rear corner of each spoiler) so it lays flat when not extended.

This approach has the advantage of not stressing the servos in the down-spoiler position. It also has the advantage of me not having to work out the position of the servo, the rotation diameter and angle of the arm, the length of the arm glued to the spoiler blade and the length of the wire coupler between the servo arm and spoiler arm.

Thoughts and comments are welcome. As are helpful suggestions.

W
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Last edited by wingloada; Dec 08, 2012 at 09:24 AM.
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Old Dec 07, 2012, 09:06 PM
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United States, MD, Lutherville-Timonium
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My House is not big enough

Here's the thing put together for the first time.
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Last edited by wingloada; Dec 08, 2012 at 12:16 PM. Reason: Better photo stitching
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Old Dec 09, 2012, 03:24 PM
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United States, TX, Richmond
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Quote:
Originally Posted by wingloada View Post
Soon these will be joined.

I planned to use 10-32 nylon bolts for the wing mounting to the fuselage, which has steel nuts embedded in F3 and F4. I have also seen people use a steel 10-32 bolt in the front mount and a nylon bolt in the rear with the idea that a wing strike will rotate on the steel bolt but sheer the nylon bolt and the steel front bolt is stronger for wing security.

Those of you with more experience than I, will two 10-32 nylon bolts be sufficiently strong for the wing-fuse connection?

W

I've used 2 - 1/4X20 nylon screws before on my modified BoT bolt on 3 piece wing but I probably could have gotten away with 2- 10-32, as that's what I used on my Yardbird... I prefer Nylon to steel for the reason you give, steel would transfer the forces more to the fuse and wing structure.

Inspect them regularly, and replace them when they begin to look worn/bent.

AJ
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Old Dec 09, 2012, 04:44 PM
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United States, MD, Lutherville-Timonium
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Thanks for the help AJ. If your Yardbird stood up to winch launches with the 10-32 nylon bolts, that's a strong indicator, I think, that they will do the job with my HH wing-Yardbird fuse hybrid. Has anyone ever seen a 3.5M wing blast off due to 10-32 nylon bolts failing? These are the same bolts that Mark Drela recommends for his Allegro Lite, but then that's a 2M.

B
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