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Jan 23, 2012, 01:20 PM
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Quote:
Originally Posted by Vernon Hunt
Kent,

Oh, that wing is looking good. Whats the wingspan? Very nice.

Vern
2.84 meters
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Feb 02, 2012, 12:30 AM
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elevons and pull/pull


Finishing up as much as I can on each wing panel before joining the wing halves together. The pull/pull linkage is getting a bench test and it works well. The elevon can travel from 90 deg. up to maybe 20 deg. down. Very smooth and rigid with the pulleys and kevlar braided cord.

The servos will mounted in the nose on slide plates to allow for tightening of the pull/pull. Must join wings before servos are installed.

Kent
Feb 02, 2012, 05:43 AM
Deniable plausibility
Shedofdread's Avatar
Looking very good! BTW what's the kevlar braided cord usually sold for? Some kind of fishing thing?

What sort of servos are you using? I'm guessing you're using ones with pretty good gear trains / bearings? Just wondering if there's any mileage in using an external bearing to relieve the load on the servo's top bearing? Probably not but just thought I'd float idea before it's all installed / fininshed.
Feb 02, 2012, 09:18 AM
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Hi Shed,

The braided kevlar cord is no doubt used for many things. I got it from ACP Composites. They also have the tiny delrin pulleys.

This application would be the perfect example for an external bearing or a separate idler pulley. On the servo, not only are linkage loads even more eccentric to the top bearing than normal, but they are always under the load of the cord tension. Although I love to fly, I don't think that I'll logging so many hours to justify the added work.

These are big standard Hitec servos. They have performed well in the past with side mounted pulleys, such as these. In fact, their strength have saved me in the past. While flying a 1/4 scale ship at the beach, I noticed a slightly slow elevator response. Upon inspection, I found the pushrod was jambed with sand and I could barely move it by hand, yet the servo was able to operate it at a near normal level. I've been a "believer" since then.

Kent
Feb 08, 2012, 09:10 PM
Registered User
Interesting build Neatly done too.
I'm astounded at the extensive use of "lite ply' though.
Imo/experiences that 'stuff' has all the structural integrity of stale Pasta. Brittle /fragile are the only descrpitors that have merit.
Hope it holds up for you.
Feb 09, 2012, 09:12 AM
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Quote:
Originally Posted by Bare
structural integrity of stale Pasta. .
The same thing can be said for carbon fiber. It's all a matter of stress.

Structurally speaking, I put lite ply in between balsa and basswood. Balsa has good strength/weight ratio, but suffers from very weak cross grain bending. lite ply is has strength in all directions, which makes it a good candidate for laser cut parts.

Kent
Feb 12, 2012, 10:38 AM
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I threw a quick knot around the servo pulley for a little pull/pull testing.
Now to see what can be done with that stiff hinge on the other side.

Kent

Horten Xc linkage (0 min 17 sec)
Feb 12, 2012, 12:11 PM
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Quick61's Avatar
Very slick and smooth Kent. Would you happen to have any clear pix of the spot where the cord makes it's turn? Looks like about 70* or so, right? I'm not seeing that part clearly in the video.

Mark
Feb 12, 2012, 12:40 PM
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Thanks Mark. The video is of the "good" side.

Do you mean the little pulleys? Post #15 has a drawing of linkage.

Kent
Feb 12, 2012, 06:09 PM
Just call me crash for short
Quick61's Avatar
Yea, the pulleys, those are the shots I was looking for. Thanks. Living large on the old saying, "the bigger the glob, the better the job" are we? (just kidding) Nice setup all in all. I'm sure you'll get the other side sorted out in short order. It's all looking great.

Mark
Feb 17, 2012, 06:48 PM
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Leading Edge


Luckily I found a spare piece of pine base molding for the LE. The thick (15%) root airfoil has LE big enough to start a lumber yard. Next time I'll use basswood or just wrap the LE in plywood.

Kent
Feb 17, 2012, 07:38 PM
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Oh my


I just checked and SO FAR the wing loading is 11.6 oz/s.f.
Nose lead and covering yet to do.
This plane is going to MOVE.

Even at this size, 2.84m, it's safe to say that it's no floater, but I thermal my little 60" le Fish and it's at 18 oz/s.f.

Kent
Feb 17, 2012, 10:47 PM
Just call me crash for short
Quick61's Avatar
Hey Kent, that LE looked shiny unstained. Sure is coming out to be one great looking ship. Base molding... your a man after my own proclivities. Use what you got and the the hot place with "what is suppose to be". In the end, I'll almost bet you will be glad you used it. What was it, Fir, Yellow Pine...?


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