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Mounting Servos In the Wings? Servo Questions

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Old 10-01-2011, 11:48 AM
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Default Mounting Servos In the Wings? Servo Questions



We are currently building the Top Flite Corsair F4U 60. We discussed putting servos in the wings to control the ailerons. We fear that if we do this, it will add too much weight. The airplane is going to have 2 standard servos controlling the flaps. 2 Electric Retracts in each wing. We have discussed putting in two hatches to cover the bell cranks. My main issue is, Ithink that the nylon flex rods will expand/contract causing my model to get out of trim every flight. This isn't huge problem with Elevators. But Idon't like to deal with it from side to side. I was wondering if two mini servos would have enough torque to handle the ailerons? Also Iwas curious if we are to mount them in the wings if they should be done vertically or on the side. (like the zlin 526) On the zlin my made the servo hatches and rails one piece, thus the servo was mounted to the hatch and hidden. As you can see by the photo below. If one were to add servos, you would haft to add material to support the servos. Ihave never made this type of alteration to a plane before!


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Old 10-01-2011, 12:11 PM
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Default RE: Mounting Servos In the Wings? Servo Questions

It should be fine. What I've done in the past is make another spar in the wing so the wing itself has extra strength if it is a concern to you and other people. And I would also balsa sheet around the servo tray and make a basswood frame around the servo bay attatching it to the ribs itself.

On yours I'd ad the extra spar towards the rear of the wing either on the top or bottom. JMHO





If you are going to glass the wing, then I wouldn't worry to much about it. If not what I've drawn up for you has worked well for me in the past. Another thing I almost forgot is I've balsa sheeted around the suspected weak area then used Balsarite Conditioner or Ultra thin CA to harden the wood for extra strength.

Nice work so far, looking good!


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Old 10-01-2011, 12:20 PM
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Default RE: Mounting Servos In the Wings? Servo Questions

Two of these http://www.servocity.com/html/hs-a5076hb_servo.html are light and should handle the job. Remember, one 'standard' servo is all they recommend to handle both.
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Old 10-01-2011, 03:52 PM
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Default RE: Mounting Servos In the Wings? Servo Questions

Ailerons don't require a lot of power. I think I used the HS 81s in mine. Worked just fine. I mount the servos to the hatch so they are sideways. You can install them in many ways, hatch and just the top sticking out is another. There isn't a lot of added weight to the wing with the servos and hatches. I just buttoned up the hatches on my new plane or I would have shown you a photo. I'm sure Mike or Ken can give you a nice drawing to follow.
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Old 10-01-2011, 05:31 PM
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Default RE: Mounting Servos In the Wings? Servo Questions

Think you guys are right.  I think putting servos in the wings is best way to go.  However shortly after writing this thread My Dad decided to glue in the bell cranks.  He doesn't want to alter the way the kit designers did things.  (((shruggs)))  I don't understand why most of these older kits used only one servo to power the ailerons.  For example I have just one servo powering 4 ailerons on the Sig Hog Bip!  Of course it works "ok"  But you hear flutter when the biplane is over half throttle.  (I usually fly it at half throttle.  More realistic that way)   At least He's allowing us to use the dubro ball link, which is suggested in my last thread.  The tail controls are installed exactly the way kit designers want it.  (I'm not hep on it, but ok)  We decided, to turn the Elevator push rod around.  In other words their will be a z bend on the Elevator And a clasp on the servo end.  I wish I could talk him into putting servos in the wings.  But He argues if we do that, then we haft to install extensions which might come apart.  Of course you can tape them or heat shrink them together (We've done that on some of our other planes)  He also argues that making servo rails etc is "To Hard"  Anyways I just wanted to thank you all for your advice!  Most of it has been considered, and I've gotten as much of it worked in to the kit building as possible!
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Old 10-01-2011, 05:47 PM
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Default RE: Mounting Servos In the Wings? Servo Questions

These are very old designs and that's how it was done when we were still wearing bow ties and high button shoes. Back then a 4 channel radio would put you in tall cotton. Ys and bell cranks were the way to go. Then along comes computer radios and huge selections of servos. We then had enough channels and mixing in a radio to do things a better or easier way. The times have changed but the old kits are still being cut the same old way with the same old instructions. All the old ways still work but there are better choices and ways to do things these days. When driving I still like to shift the gears myself but I have an automatic trans in my van, the Mustang has a stick, best of both worlds.
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Old 10-01-2011, 05:52 PM
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Default RE: Mounting Servos In the Wings? Servo Questions

Thank you Mr. Gray Beard.  And I agree with you!  I still only fly with 4 channels.  This will be the first model I have ever used more than 4.  I'm going to be using Hitec's Lazor 6.  I currently drive a stick. 
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Old 10-02-2011, 05:08 AM
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Default RE: Mounting Servos In the Wings? Servo Questions

The switch will probably not add any weight since you'll be eliminating the bell cranks and pushrods. The original design was a compromise to accommodate the 4 ch radios that most modelers had then and to save weight with the humongous servos they used then. It isn't the way they would have done it had they had the options we have now though.
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Old 10-02-2011, 09:20 AM
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Default RE: Mounting Servos In the Wings? Servo Questions

The old design worked and worked well. Old doesn't mean useless. I built a little pattern plane a while back from plans. My building partner talked me into building it as stock {old school} as I could force myself. I used the old style hardwood motor mount blocks instead of a new type of mount. They work great, good vibration damping and strong. I had to mount the engine upright though {old school} and there is no way to divert the exhaust enough to keep it from slathering engine snot all over the plane. As nice as it flys it's a total pain to clean up at the end of the day. It's also my only trike geared plane, big surprise, it is the best ground handling plane I have on those real windy days. My tail dragger's weather vain while trying to bring them back into the pit area, this one I can steer right into the pits. Old school does work, we just have better ways these days.
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Old 10-02-2011, 11:04 AM
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Default RE: Mounting Servos In the Wings? Servo Questions

This is my personal favorite method,,pictures are self explanatory
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Old 10-02-2011, 03:00 PM
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Default RE: Mounting Servos In the Wings? Servo Questions

^  I really like that method, but my dad totally hates it , and called it ugly.  (((shruggs)))  He said If that is the way I want it, then I haft to do it myself...  Is that a mini servo your using?
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Old 10-02-2011, 03:21 PM
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Default RE: Mounting Servos In the Wings? Servo Questions

I do it the same way but install two side rails along the ribs.
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Old 10-02-2011, 03:25 PM
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Default RE: Mounting Servos In the Wings? Servo Questions

Here is some more photos of the location that the servo would be installed:


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Old 10-02-2011, 03:31 PM
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Default RE: Mounting Servos In the Wings? Servo Questions

That is a Half Horizontal stab of 96" span CL-415,, It will be a full size servo, and there will be 6 of those hatch/servo mounts 2 per wing, one per Stab half, the servo in there for the picture was a HS-5645 with the Blue aluminum arm,,

Tell your dad I said,, when the plane is doing 120 MPH and the bell cranks cause the ailerons to flutter off the plane,, my method will start looking pretty darn good


Good luck
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Old 10-02-2011, 03:35 PM
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Default RE: Mounting Servos In the Wings? Servo Questions

I think with as narrow as my wings are.  A mini servo would probably fit the best.  But I think the balsa ribs should be doubled with something, before putting is corner pieces or rails like Gray Beard mentioned. 
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Old 10-02-2011, 04:25 PM
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Default RE: Mounting Servos In the Wings? Servo Questions

??????? they look like 3/32 so that should be strong enough. The hatch turns into part of the bracing.It's just one of those things you have to look at and decide for yourself. If a servo is set up with a nice linear push and pull there isn't much pressure placed on the ribs at all. You can also have the rails epoxy up against the wing spar for added strength. Don't over think things. I used to get a lot of static from my advanced instructor because I tend to over engineer things. Today I try to avoid as much of that thinking stuff as I can.
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Old 10-02-2011, 04:47 PM
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Default RE: Mounting Servos In the Wings? Servo Questions

Quote:
ORIGINAL: gregoryshock

I think with as narrow as my wings are. A mini servo would probably fit the best. But I think the balsa ribs should be doubled with something, before putting is corner pieces or rails like Gray Beard mentioned.
If the can support that bellcrank, they can support a hatch/mount. Doesn't that wing get sheeted too?

You could always move the servo up closer to the spar where the airfoil is thicker, I don't like using Mini or Micros for control surfaces on planes 40 size and up,, I know they have them rated @ 40 oz +. but the gear trains are still smaller,, I'd use a standard size servo. you only need just over 3/4" of space
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Old 10-02-2011, 05:39 PM
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Default RE: Mounting Servos In the Wings? Servo Questions

The control surfaces on that plane are small with about 10 degrees of throw. I use the HS 81s for race planes ailerons so they should work on a sport warbird. They worked on my F4U.
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Old 10-08-2011, 09:11 AM
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Default RE: Mounting Servos In the Wings? Servo Questions

I finally convinced my dad that we should put the servos in the wings.  (He's not too happy about the extra work)  We are currently designing it.  I'll post some photos, to see what you guys think. 
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Old 10-08-2011, 09:16 AM
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Default RE: Mounting Servos In the Wings? Servo Questions

I roll paper around a 1/2 inch dowel and run that through the ribs for the servo wires, makes it easy to remove or replace the servo. Once a wing has been built installing a wire tube becomes a problem. I have forgot to install the tube a number of times during a build so I know the troubles of getting it in there.
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Old 10-08-2011, 09:21 AM
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Default RE: Mounting Servos In the Wings? Servo Questions

Mr. Gray Beard, I'm having trouble visualizing what your talking about.  I was merely going to install it the way scale only 4 me posted.
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Old 10-08-2011, 09:52 AM
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Default RE: Mounting Servos In the Wings? Servo Questions


Quote:
ORIGINAL: gregoryshock

Mr. Gray Beard, I'm having trouble visualizing what your talking about. I was merely going to install it the way scale only 4 me posted.
Maybe SCFM has a photo on hand to show you, I don't want to remove a hatch right now and have nothing showing it during the build. Think about it a little and while looking at his photo ask yourself, Where Are/How Are the wirse from the servo going to get from the wing to the RX? I'm going out to the shop now and I will take a camera with me, maybe I have something I can show you.
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Old 10-08-2011, 10:45 AM
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Default RE: Mounting Servos In the Wings? Servo Questions

You made a wise decision to put a servo in each wing. A bellcrank (the original way) often wound up with lots of slop or play due to the increased number of clevises/zbends etc. which often led to flutter problems. To minimize the probability of flutter, you want very stiff controls with no slop; the shorter and stiffer the push rod from the servo to the control horn, the better.
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Old 10-08-2011, 10:56 AM
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Default RE: Mounting Servos In the Wings? Servo Questions

Three photos for you, the best I could do at this time. The hatch with the servo mounted on it sideways like SO4M showed you. Inside of the hatch bay you can see where the wires go into a tube. That tube runs all the way through the wing ribs from the hatch bay to the wings center section then the wires come out so they can plug into the RX. During a build it is easy to do. Once a wing has been built it is harder but because I tend to forget that tube quite often I can tell you it can be done.
Don't over think things when your building. After the tubes arre in I usually coat them with thin CA so they are stiff.
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Old 10-08-2011, 02:27 PM
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Default RE: Mounting Servos In the Wings? Servo Questions

The paper tube does make things easier, but if you don't install them you just need opening in each rib gig enough for the servo connector to slip through..
I've before too a small fishing weight (pinch on) and fishing line, let the weight works its way through the holes in the wing,, then use the line to pull the servo wire through.

I'll take a few more detail pics and add them to what I and GB has already shown you,,it will be later tonight though.
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