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Old Nov 15, 2012, 12:43 AM
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Kevin,

this you've got to explain, I can't seem to get my head 'round it:

how d'ya get the servo horns on to the servo pinion and then bolt 'em down with no side access to a driver?

Are the elevator servos installed in to the core in the same way as for the ailerons?

David
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Old Nov 15, 2012, 06:21 PM
Kevin S. Gribben
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Yes, nothing more exotic that cutting them into the cores and sheeting over the top of them. On the Atalanta it has a removalble stab (dont ask me why) so the stab has hatches that can be acsessed when you slide the stab off. The wing has the servos comitted under the skin.

Agressive but pretty. I just have never had to change a wing servo. When you start engineering a good hatch with achors for the servo then achors for the hatch, then the 8 screws, it just doesnt make sense.
I am sure when I have to cut one of these out I am going to feel differnt, but they are pretty once completed.
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Old Nov 15, 2012, 06:22 PM
Kevin S. Gribben
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wing servo
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Old Nov 15, 2012, 06:35 PM
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Kevin,

thanks for the explanation but I don't follow how you access the servo arm. Assuming it is in place when you install the servo and then leave it there when you sheet the wing, well, it's in place and no need to access it.

If for any reason, the servo arm should break or need replacing, can it be removed? Wouldn't you need to access the top of the servo with a screw driver to remove the arm?

I figured you have a system to install the servo, sheet the wing and then, whenever you want install and remove the servo arm. True?

David

P.S. Will be getting back to your insightful email later tonight. I'm a drawin' while the wee family is out!
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Old Nov 15, 2012, 07:25 PM
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My guess is you just play the odds on breaking a servo arm.


David
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Old Nov 17, 2012, 11:05 AM
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Don't European guys do this on their models as a matter of course. I recall seeing this on several models.
Chris...
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Old Nov 27, 2012, 10:55 AM
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as a European (at least nominally) I've only ever seen the servo built into the wing in gliders, usually of the small foam variety. Even the big glass soarers with glued in servos have an access hatch over them. Multiplex like the buried servo in their small electric powered all foam models like the Funjet but that's not a veneered wing!
On my wing mounted servos I either use a plastic servo mount that forms the hatch or make one from 1/16" ply and a couple of blocks. Occasionally I'll use a couple of servo rails across two ribs with the top of the servo proud of the wing just to ring the changes.

There is one setup (an old one) that would look the same. It used to be quite common to use 90 degree belcranks set out in the wing with pushrods to a single central servo. That would look like Kevin's setup but would have a lot more lost movement between the servo and aileron.
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Old Nov 27, 2012, 11:35 AM
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Quote:
Originally Posted by BrumBob View Post
There is one setup (an old one) that would look the same. It used to be quite common to use 90 degree belcranks set out in the wing with pushrods to a single central servo. That would look like Kevin's setup but would have a lot more lost movement between the servo and aileron.
Bob,

good comments.

The above setup is as old as I am (actually, older). I remember building several models with the infamous bellcranks which made a lot of sense to me at the time when transitioning from C/L models to R/C. We were always on the lookout for the next slickest bellcrank linkage.

Today, in a pattern ship, and in a foam core wing, this has got to be the least desired setup I can think of. The whole concept of putting the linkage near the control is to have a short, positive, no play, setup. Introducing bellcranks and multiple linkages not only makes it difficult if not impossible to adjust but the original concept is lost. One might as well use torque rods which can be adjusted since the servo is in the middle anyway.

Companies like Futaba have even designed servo cases specifically for a smooth wing bottom where the servo is mounted. It might put the linkage on the outside "ruining" the looks but everything is easy to maintain and adjust when needed.

I probably couldn't bring myself to cut into a nice finish such as those done by Kevin if something were to go wrong with the servo.

David
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Old Nov 27, 2012, 12:18 PM
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I fly sailplanes a lot so this is an interesting cross over . The current gen 3M+ F3J/F3F competition sailplanes use both servo frames and gluing the servo directly to the composite skin. Both methods work great, as long as the builder takes care in how the servo is supported so that there is no movement of the wing skin. The servos in foam wings (like in a DLG) are almost always glued in.

As Bob noted the difference with Kevin's build is there's no hatch, so it would require cutting into the sheeting to service. It definitely saves weight and produce a beautiful finish - nice to see how he did it. I agree with Kevin on the reliability of todays servos, for our application you would rarely need ever to change. I would do this if the wing is monokoted... though maybe not for a painted wing!

As for the servo arm, I've never had one break. The reliability of servos today are very good. Our sailplanes take constant beating especially the flap servos, but they are glued in because we don't often change them. Of course, we use very high quality servos and they are all metal geared.

For the Atlanta, I might paint the fuse but monokote the wings to save weight. If I go that route, I'll glue the servos in, but use a hatch that is tack glued in just like on the sailplanes. No additional weight and no protruding screws, and easier to service the servo if necessary.
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Old Dec 08, 2012, 02:43 AM
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Here's a question on the retracts. I was originally planning for electric, but just realized that electric retracts might not go so well for the nose wheel. I mean it is sitting right next to the hot exhaust header inside an enclosed pan, almost touching. It definitely is hot there, and electric retracts and wires will not likey...

Should I spring for a set of MK SP mechanicals old style? The mains are already cut out in the wings and MKs will drop in. Or should I go with electrics and make a heat shield for the nose gear? It's going to be a lot to take for the nose retracts, heat and vibration and all... tough life! What do you guys think?

Kevin I think you had the kawasaki Atlanta with e-flite electric retracts?
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Old Dec 08, 2012, 01:38 PM
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Matt,

I think the E Flites are a no-go on nitro classics. Tony had them in his P 7 and the vibration shook the nose gear apart. I run MKs on my Atlanta. I went to 2 servos with MKs on the C4, much easier. Spring Airs are the gear of choice for Kevin.

Doug
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Old Dec 08, 2012, 08:21 PM
Kevin S. Gribben
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Ya the Eflights have been a bust so far. The make a nice medium sized set but I am skittish to put then in on a "full" build. Nobody has had good luck on any of the P7's I have seen flown. I have been flyin the spring airs since the 80's with good luck....... but really want the air pump out of my flight box.
My current thought is to retrofit the sring airs with the "Down and Locked" actuators, currently that is the setup I am working tword. Though the $200 to Spring Air, then another $300 to down and lock seems stiff. Non of the chinese $79 solutions seem to have high resolution trunion blocks or steering systems that strike me pretty.
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Old Nov 03, 2013, 07:32 PM
Boo
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Quote:
Originally Posted by Pitstop000 View Post
Oh, by the way the wing dihedral is wrong in the manuals.
Sorry for the late reply but what should the dihedral be on an Atlanta ?

Boo
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Old Nov 03, 2013, 09:29 PM
Paul Pappas AMA 42520
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Hi Boo,

If using the method in the instruction manual for measuring the dihedral it should be 6mm.

To make it easier though just place the wing halves upside down on a flat bench and raise the center to 6mm, just make sure you’re leading and trailing edges are equidistant from the bench top.
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Old Nov 05, 2013, 08:58 PM
Boo
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Quote:
Originally Posted by Pitstop000 View Post
If using the method in the instruction manual for measuring the dihedral it should be 6mm.

To make it easier though just place the wing halves upside down on a flat bench and raise the center to 6mm, just make sure you’re leading and trailing edges are equidistant from the bench top.
Thanks for the info and tip.

Boo
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