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futaba servo question.

Old 06-02-2011, 07:06 AM
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Turqui
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Default futaba servo question.

hi there; i have a top flite cessna 182 gold edition kit; and i previpusly flew it with a futaba 3003 servo in the elevator; after a while i decided to fly the plane again and will like to know if this servo is good enough for the elevator? its very hard to replace.any ideas.
Old 06-02-2011, 07:09 AM
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MinnFlyer
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Default RE: futaba servo question.

I would think that it should be ok. It's not like you'll be doing any high-stress maneuvers with a Cessna 182
Old 06-02-2011, 08:34 AM
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Default RE: futaba servo question.

I would think if it was adaquate before it would be adaquate now.

Watch those blenders and waterfalls though
Old 06-02-2011, 01:45 PM
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Default RE: futaba servo question.

It was not that many years ago we all flew much bigger and faster planes with stock servos. I still have an old Goldberg Sukhoi that uses one servo with a split rod for both elev halves. It is a 72" span and Webra 1.20 powered. It flew many years with stock servos every where. I would not dream of doing it nowadays. Just goes to show we sometimes over engineer our planes.


david
Old 06-02-2011, 05:05 PM
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Default RE: futaba servo question.

Yep, 48 inch pounds was a pretty big servo. As the planes got bigger is when you started seeing two or more servos ganged on one control surface.
Old 06-02-2011, 05:43 PM
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Turqui
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Default RE: futaba servo question.

Thanks everibody for your comments. One more thing; i have noticed that one of the alieron servos ot doesnt perform like the otherone; they are 3004 and they are athached with a "y"harnes; basically if i move the stick both sides with a fast movement; they react perfect; but if i move the stick slow; the right servo goes up and the left doesnt go down, but wen the left go up, the right goes foen like it should; any ideas?
Thanks.
Old 06-03-2011, 11:37 AM
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Rodney
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Default RE: futaba servo question.

ORIGINAL: Turqui

Thanks everibody for your comments. One more thing; i have noticed that one of the alieron servos ot doesnt perform like the otherone; they are 3004 and they are athached with a ''y''harnes; basically if i move the stick both sides with a fast movement; they react perfect; but if i move the stick slow; the right servo goes up and the left doesnt go down, but wen the left go up, the right goes foen like it should; any ideas?
Thanks.
Most likely a poor connection at one of the connectors. Unplug and replug all connectors on the side of the servo not performing properly. Double check for partially damaged wires (broken strands, poor crimp etc.) as usually an intermittent or bad connection will give the type of problem you are seeing.
Old 06-06-2011, 10:09 PM
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Default RE: futaba servo question.

Turqui

The consensus seems to be using your, (I am assuming), Futaba S3004 servowill beo.k. with your Top Flite Gold Edition Cessna 182. I am not so sure that I agree. The Top Flite Gold Edition Cessna kit builds out to a 81" wingspan and weighs about 10-12 pounds. I am building a de Havilland Chipmunk with a 81" wingspan and it will weigh about 10-10.5 pounds. I had a similar concern as you regarding servo's for this plane. After much research, I am going with Hitec HS-645MG servo's for the ailerons, elevator, and rudder. I will use HS-485HB servo's for the flaps. I am using one servo for each control surface, eg., 2 for the ailerons, and 2 for the flaps. The Hitec HS-645MG servo's provide ~ 107oz/in at 4.8v. The HS-485HB servo's give ~ 66oz/in at 4.8v. The HS-645 has metal gears and the HS-485 have Karbonite gears. Check the size of your control surfaces on the Cessna and consider that you are going to be flying a 10-12 pound plane. At any speed, its the area x mass, (weight) coupledwith the resistance, (angle of deflection),that equals the force on the servo. Your Futaba S3004 only produces about 44oz/in of torque at 4.8v. It's just my personal opinion, but that's not a lot of torque for even a big loop with a 10-12 pound plane. Most of the smaller .40 to .60 size planes are in the 5-8 pound range.

I would suggest you at least considerthe Futaba S3010 servo, which gives~ 72oz/in of torque at 4.8v and the price won't break you.Good luck with your Cessna build. It's a beautifulplane.
Old 03-26-2014, 06:35 AM
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Default De Havilland Chipmunk elevator

I am having trouble with my elevators on my De Havilland Chipmunk. This model has one servo in the center servo tray for the elevators with very long control linkage that flex too much after exiting the fuselage. Did you convert yours to dual tail fuselage servos? If not how did you deal with the linkage flex?
Thanks
Old 03-26-2014, 12:43 PM
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http://www.darrolcady.com/Carbon_Fiber/carbon_fiber.htm

Good Day Aug, I'll take a shot at your wet noodle pushrod problem. First let me express my opinion. Modifying an aircraft that was normally equipped or smaller airplanes to rear fuselage mounted servo is a mistake and a poor bandaid for the real problem and that is wet noodle pushrods.

In many cases wet noodle pushrods are caused simply because they are either unsupported along the middle sections if they are the flexible type or if they are the stiff type, not straight from the front to the rear. putting small bends in the aft wire portion where they exit the fuselage is a common cause of the wet noodle syndrome which acts just like built in Expo whether you want it or not.

To make a truly straight push rod is not that hard except it means you normally have to put the fuselage outlet hole where it needs to be and not where so many manufacturers so carelessly place these outlets.

These days I use carbon fiber push rods in everything but not the rods that are sold by the big mail order houses. I get my rods from the link above, it is a cottage industry supplier to the pylon racing community and some electric. It is the only place to easily get these rods and they are not the same sold by others. Those are to big and require special end fittings. What Derrol sells are rods that are perfect slip fit for either 2/56 or 4/40 rod end wires there are not fitting required and you will find these rods are very, very easy to set up perfectly once you learn the procedure.

When I introduced this method in our local club some years back it caught on like wildfire and 75% here that's all they use. Now you go to that link above Derrol has an excellent tutorial on the method and sells both size rods rather inexpensively.

John
Old 03-27-2014, 01:15 AM
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In many cases a simple metal pushrod will cure the flex problem.

As John says, the nyrod needs to be supported inside the fuselage. I run metal pushrods on the outside, screwing them into the nyrod at least 2 inches.
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Old 03-27-2014, 03:33 AM
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Default Wet Noodle Push Rods

Originally Posted by JohnBuckner View Post
http://www.darrolcady.com/Carbon_Fiber/carbon_fiber.htm

Good Day Aug, I'll take a shot at your wet noodle pushrod problem. First let me express my opinion. Modifying an aircraft that was normally equipped or smaller airplanes to rear fuselage mounted servo is a mistake and a poor bandaid for the real problem and that is wet noodle pushrods.

In many cases wet noodle pushrods are caused simply because they are either unsupported along the middle sections if they are the flexible type or if they are the stiff type, not straight from the front to the rear. putting small bends in the aft wire portion where they exit the fuselage is a common cause of the wet noodle syndrome which acts just like built in Expo whether you want it or not.

To make a truly straight push rod is not that hard except it means you normally have to put the fuselage outlet hole where it needs to be and not where so many manufacturers so carelessly place these outlets.

These days I use carbon fiber push rods in everything but not the rods that are sold by the big mail order houses. I get my rods from the link above, it is a cottage industry supplier to the pylon racing community and some electric. It is the only place to easily get these rods and they are not the same sold by others. Those are to big and require special end fittings. What Derrol sells are rods that are perfect slip fit for either 2/56 or 4/40 rod end wires there are not fitting required and you will find these rods are very, very easy to set up perfectly once you learn the procedure.

When I introduced this method in our local club some years back it caught on like wildfire and 75% here that's all they use. Now you go to that link above Derrol has an excellent tutorial on the method and sells both size rods rather inexpensively.

John
Thank you John for your response. I'm attaching photos so you can see exactly what I'm up against. The problem is between after the push rod leaves the fuselage and the control arm. Will this carbon fiber rod still not flex? Will it snap if I pull up hard from a power dive because it is no longer inside the tube? I'm using a DLE 20cc for the engine. Also it would be very difficult to get the push rods to exit closer to the elevators due to the tail wheel assembly.
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Last edited by Aug; 03-27-2014 at 05:33 AM.
Old 03-27-2014, 05:40 AM
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Ah, Aug the issue you're up against is that those flexible nyrods aren't suitable for that application.
the inner yellow nyrod portion really NEEDS to be supported particularly at the servo end, in the middle, and right up to the control horn itself.
John's explanation is spot on, and the photo TomCrump posted is exactly how your nyrods should look (IF you stay with nyrods.)

Note how Tom's installation has NO exposed nyrod.

to fix the issue, you MAY get away with simply replacing the threaded metal portion where the elevator control clevis attaches to the elevator with a straight steel threaded piece (as in Tom's photo)
or, you may need to remove the nyrods entirely and replace with the sort of carbon rods that John mentions.

one other thing, for the future when you're connecting dual elevators using a single servo (two pushrods, one servo) you'll find it much easier to match the geometry for both pushrods if you lay the elevator servo on it's SIDE,
(not upright)

hope that helps!

(WOW I just noticed the original posting was from a couple years ago... I'm missing my Brother right about now RIP Mikey.)
Old 03-27-2014, 05:50 AM
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OK Aug now you are cooking and pictures are 'worth more than a thousand words' Yes you have an extreme wet noodle installation, in a dive on a pull up the elevators will suffer 'blow back' which is just like adding a large amount of expotential only in the up direction.

First I want to address one slightly unrelated problem you have. The post type control horns you have are great and I use that exact one a lot in fact I by that horn in bulk to always have on hand. The problem is on the elevators you have them on backwards and the clevis point is to far back behind the hinge line what this will do is introduce unwanted differential with the elevator going further in one direction than the other. The hinge point of the clevis should always be even with the hinge line of the surface. That's why that type of horn has the extended hinge point.

Now to your rods the worst situation is you have long unsupported bends in the elevator and one of the elevator rods that is coupled with the other half has that huge, did I say big ninety degree bend? This will never be flex free. The push rods must be straight or very, very close to it. To answer your questions yes if they are straight the carbon rods will be far better and very strong, carbon rods can be broke if you try to bend them sideways the strength is all in the push/pull axis you cannot bend them.

I am going to show you some photos of my use of these rods as well as the same horns on a number of airplanes and two of which use the same dual elevator pushrods and separate rods for the tailwheel which you also have. will have photos up in another hour as I have to change computer to attach photos.

John
Old 03-27-2014, 06:28 AM
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Old 03-27-2014, 11:01 AM
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Thank you John, Jim and Tom. You've been a big help. I think I'm OK now following your advice.
Old 03-27-2014, 11:22 AM
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Thanks Aug, I did neglect to mention just one last thing that has always worked for me in testing my own work or someone else's and it is the litmus test of how to check pushrods.

What I do is to make sure the radio system is off then with the control surface in neutral position, grasp the surface in the area near control horn with one hand and with the other hand holding the servos output arm and attempt to move the surface so the pushrod is trying to move the servos arm that you are holding in position. This will immediately show any wet noodle flexing and exactly where it is occurring from the control horn all the way to the servo.

The last test is to grasp the control surface near the horn and it fails if I cannot move the surface carefully from stop to stop in both directions without holding the servo and the switch off. If you can do this Ya'll got a fine pushrod system.

John
Old 03-27-2014, 11:57 AM
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Originally Posted by JohnBuckner View Post
Thanks Aug, I did neglect to mention just one last thing that has always worked for me in testing my own work or someone else's and it is the litmus test of how to check pushrods.

What I do is to make sure the radio system is off then with the control surface in neutral position, grasp the surface in the area near control horn with one hand and with the other hand holding the servos output arm and attempt to move the surface so the pushrod is trying to move the servos arm that you are holding in position. This will immediately show any wet noodle flexing and exactly where it is occurring from the control horn all the way to the servo.

The last test is to grasp the control surface near the horn and it fails if I cannot move the surface carefully from stop to stop in both directions without holding the servo and the switch off. If you can do this Ya'll got a fine pushrod system.

John
+1
I do this immediately before installing the servos.. I simply grasp the surface (or hold it in place mechanically with a couple of C clamps and paint stirrers) and try to move the pushrods by hand (with the servos disconnected/ not installed)
if it's going to flex, I can see it then.

added benefit, it also makes any binding in the pushrods or hinges become obvious.
Old 03-27-2014, 03:22 PM
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Good tip....Thanks again.
Old 03-29-2014, 08:39 AM
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I test mine a little differently. I hold the control surface still and push the servo to full deflection. The amount of servo horn movement tells me how good my pushrod is. It only has to be stiff enough to resist the servo torque, so if I can go to full deflection it's strong enough.
Old 03-29-2014, 10:35 AM
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440 rods the entire length seem to have done the trick.
Old 03-29-2014, 12:18 PM
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Excellent Aug, thanks for letting us know your solution

John

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