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tail servos

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Old 01-24-2013, 10:31 AM
  #1
kargo
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Default tail servos

OK, I Give, Uncle, I surrender, white flag...

I've looked but have not been able to find (during the morning) a good example of how to mount servos in the tail of my Hangar 9 super stick (40). The tail part of the fuse busted after purchasing it used, and was rebuilt such that pushrods are kinda difficult. So it struck me, why not just mount those servos in the tail! Can anyone point me to some good examples of how to go about this? I've looked for instruction manuals, photos, posts, etc and come up empty handed. I'm guessing some ply or basswood strips and threaded wire, pretty simple, but would like to see a few examples before I completely frankenize my cheap stick.

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Old 01-24-2013, 04:01 PM
  #2
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Default RE: tail servos

You can download almost any ARF construction booklet (try a HH Katana 50) to see the graphics of it. You'll have to build a sturdy mount as well. You will be adding a pile of tailweight that will need to be counterbalanced in the nose.

Just my $.02
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Old 01-24-2013, 08:03 PM
  #3
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Default RE: tail servos

Thanks! I know the tailweight issue. Just trying to sort out some options for dealing with my current situation...
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Old 01-25-2013, 04:06 AM
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Default RE: tail servos


Quote:
ORIGINAL: kargo

OK, I Give, Uncle, I surrender, white flag...

I've looked but have not been able to find (during the morning) a good example of how to mount servos in the tail of my Hangar 9 super stick (40). The tail part of the fuse busted after purchasing it used, and was rebuilt such that pushrods are kinda difficult. So it struck me, why not just mount those servos in the tail! Can anyone point me to some good examples of how to go about this? I've looked for instruction manuals, photos, posts, etc and come up empty handed. I'm guessing some ply or basswood strips and threaded wire, pretty simple, but would like to see a few examples before I completely frankenize my cheap stick.

kargo
The short of it is,, Just cut out the opening the minimum size to allow the servos to fit in the fuse. Then take a piece of 1/4" square hardwood and glue to the inside where the servo mount screws will be going. Pretty easy,

you can always just tape the servos back there to test how they affect the CG before you cut them in

good luck
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Old 01-25-2013, 07:07 AM
  #5
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Default RE: tail servos

Thanks, I think I will run a CG test. I'll be making it an electric, so there should be a fair amount of weight up front. We'll see how it goes.
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Old 02-03-2013, 04:24 PM
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Default RE: tail servos

thanks again for all the input! when i did a cg test i could not believe the difference 3 oz at the tail made! it moved the cg back better than 4 inches (finger test).... soooo its routing pushrods for me. thanks kargo
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Old 02-03-2013, 04:39 PM
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Default RE: tail servos

pull pull cables take very little room and are easy to install.
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Old 02-03-2013, 08:03 PM
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Default RE: tail servos

that i haven't thought of and haven't done before. i'll run a search[&:]
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Old 02-04-2013, 09:54 AM
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Default RE: tail servos

I did my first pull pull on the CAP in my avatar. I did a bunch of research and came to the conclusion on a couple of things.

1) The hole in the control arm at the control surface should be in line with the hinge line.

2) While not 100% necessary, having the distance from the hinge line to the hole in the control horn should be that same as the distance from the center of the servo to the hole in the servo arm.

3) Running the wires strait or having them crossed makes no difference. Crossing the wires allows you to get them to exit the fuse closer to the control surface.

4) The wires need to run strait between control horns. They can't rub on anything.

5) You will most likely wind up with a little slack in the lines when the control surface is deflected. This slack is OK as it has no effect on the flying of the aircraft.

6) do not over tension the lines. Just snug is enough to remove the slack at neutral.

This should get you in the air. If needed you can raise a servo enough to make your lines miss other stuff in the fuse or other control rods.

Ken

PS. I'm sure others will be along with suggestions on pull pull.
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Old 02-04-2013, 10:48 AM
  #10
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Default RE: tail servos

Don't know what I'll do yet... pull pull sounds kinda hard. I have no idea how it'd work in the Hangar 9 super stick.

http://www.horizonhobby.com/products...Page-_-HAN1700

The wires need to run straight between the control horns... so how do you figure out the straight line through the fuse?

I appreciate the advice, I'll probably just deal with the pushrods. If I can't do that I'll need to do the pull pull...
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Old 02-05-2013, 09:04 AM
  #11
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Default RE: tail servos

I used minis on this Ultimate. Just cut the hole, put in ply reinforcement, and screwed them in place. Using two servos does take a reverse mix on the radio, so keep that in mind.

David
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Old 02-05-2013, 10:40 PM
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Default RE: tail servos


Quote:
ORIGINAL: kenh3497

I did my first pull pull on the CAP in my avatar. I did a bunch of research and came to the conclusion on a couple of things.

1) The hole in the control arm at the control surface should be in line with the hinge line.

2) While not 100% necessary, having the distance from the hinge line to the hole in the control horn should be that same as the distance from the center of the servo to the hole in the servo arm.

3) Running the wires strait or having them crossed makes no difference. Crossing the wires allows you to get them to exit the fuse closer to the control surface.

4) The wires need to run strait between control horns. They can't rub on anything.

5) You will most likely wind up with a little slack in the lines when the control surface is deflected. This slack is OK as it has no effect on the flying of the aircraft.

6) do not over tension the lines. Just snug is enough to remove the slack at neutral.

This should get you in the air. If needed you can raise a servo enough to make your lines miss other stuff in the fuse or other control rods.

Ken

PS. I'm sure others will be along with suggestions on pull pull.

Outstanding summary!

Kurt
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Old 02-06-2013, 01:57 PM
  #13
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Default RE: tail servos


Quote:
ORIGINAL: kargo

that i haven't thought of and haven't done before. i'll run a search[&:]
kargo
KarGo,

Let me suggest that you use a pair of 2 1/2" long 6-32 bolts as your horn. Simply screw itto the elevator or rudder and secure with flat washers and nuts, loctited in place. Don't use all-thread...it's cheap steel and will fatique quickly and ruin your day.

I use kevlar lines to small eye loops to attach clevises, both at the servo and at the surfaces. It is by far the lightest set-up one can use. I weighed the set-up a while back on a much larger model and found it to be something like 10 or 12 grams on elevators.Once you do it, you will realize a couple things....it's easy set-up especially if the kevlar has a plastic coating as mine does and it gives you a great deal of tensioning freedom both to top and bottom.

The plastic coating really comes in handy when finishing the install. I run a lighterflame lightly on the coating and it melts enough to stick to itself. A short piece of shrink tube makes a professional looking job
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