Two servo ailerons
 

I am building my first large R/C plane, a CG Super Chipmunk. I keep seeing forums saying that they are upgrading their airplanes (all types of planes) to two servos for the ailerons. This is my first aileron airplane, I have made many large gliders and small 2 channel airplanes. What is the real reason for two servos? Is one not strong enough or are they too far apart and a long control arm might flex? I would love to not go with another servo, but I want to do what is right. I would really appreciate your opinions! Thank you.<br type="_moz" />

RE: Two servo ailerons
 

wing span and is it two piece wing or one

RE: Two servo ailerons
 

Plain and simple, go with two servos for this type of airplane.

Bob

RE: Two servo ailerons
 

Unless there is a new release of the CG Super Chipmunk that is a lot larger than the 90 four stroke size one that CG kitted, a single aileron servo is all you need. In fact I have an older pattern plane, almost 90" span with a 120 four stroke engine and it flies just fine with a single "standard" size (50 in oz) servo on each aileron.

The issues of balancing the mechanical linkage and the servos through a match box or the likes is not something to get into for your first aileron plane. In fact, if the Chippie is your first aileron plane, I would get it finished and set it aside for a while and fly a Stick or 4* or like plane for a bit first. Gliders and powered planes are two completely different animals. Iam having issues controlling my glider as it responds so slow.Of course, I have problems controling my powered planes as the respond to quickly also. A powered plane will respond much faster to the sticks.So anover powered dual servo, super fast aileron setup is not a good jump for you yet. That is for the big, 33% planes and above and for the aerobatic crowd.

Don</p>

RE: Two servo ailerons
 

The CG Monk was designed for a single servo and it works great. Truth is you wouldn't know the difference if you used two or one. I do like to install a bigger or better servo then a standard if I was only using one. I use two aileron servos on every plane I build but only because I have a 9 ch radio and it is much easier for me to do the set up then using the old control rod system. That's about the only reason I do it. I'm really very lazy and I usually use two elevator servos too. The size of the plane makes no difference to me, I use two on trainers and 40 size planes. Some people will state there is a redundancy thing using two. Trouble is every time I have seen a servo in a duel servo set up break a gear train of quit working and lock up it was locked in an up or down position and the plane crashed anyway. The control surface size on bigger planes requires the duel servos, sometimes the length of the control will require the added servo so you aren't pushing the control from one small area.
Duel servos started showing up years ago when giant scale planes started showing up more and more. Back then a big servo was about 48 inch pounds of torque so two servos were used to have the power to move the controls. It was pretty normal to see several aileron servos on one control surface.
The Chippie only requires one aileron servo but I would use a bit bigger then a standard if I had a choice.

RE: Two servo ailerons
 

the goldberg chipmunk is an older kit design
back then bellcranks were the going thing
a single servo on each aileron will be a smoother operation
you can tame it down with dual rates on the ailerons

RE: Two servo ailerons
 

The reason for two servos ( One each side) is to optimize performance! if a single is used via pushwires and bellcranks or torque rods, you will NEVER get them both traveling the same and you will NEVER get the correct amount of differential.

RE: Two servo ailerons
 

I'm curious why you say "you will never get them both traveling the same and never get the correct differential"? We all (well some) had differential, mechanically, before computer radios. Are yo you saying it's not easy to change it if not correct the first time?

RE: Two servo ailerons
 

Kinda makes you wonder, don't it??? Perhaps setting up a control rod system is now a lost art?? I do find using my radio to do my set up and trim easier but after it is set I do it again the old fashion way, I twist the clevises then zero my radio trims. I do it all manually before the plane ever leaves my shop but after flight trim I do it again. Guess my age is showing again? Or is it still knowledge??:eek:

RE: Two servo ailerons
 

Yes I remember, my first radio was a Kraft KP5C. Given enough time one could probibly get it all sorted out mechanically. But in all honesty who is going to go fly the airplane, go home and drill a new servo wheel, try again and keep making the adjustment until it's right? How much easier and accurate is it to plug in the two servos, set the TX to dual servos, set the dual rates to desired throw then final adjust both ailerons for equal up and down movement both sides using the ATV. Final adjustment is to add diff until pure axial rolls are accomplished.

RE: Two servo ailerons
 

Keep it lite and keep it simple, I laugh when I see the "I upgraded to two servo's for ailerons"! Full scale aircraft use them and so should you. I use the fewest servo's possible on any build, bell-cranks are extremely reliable and maintenance free when installed correctly. If you are a sloppy builder or super lazy, then I guess they might be to much trouble, but I personally think installing a servo with a door is more work. ARF's started this out of ease of manufacture, but if you are building something use bell-cranks. I even use Bell-cranks in my ARF's when I bash them. The aerodynamics behind keeping the outer wing panels as light as possible is well known.

I made some custom bell-cranks for my 82" Corsair out of PC board, and it even uses scale hinging.

RE: Two servo ailerons
 

Some of us expect more out of our airplanes then others I suppose. I stand by me previous post, if you want better adjustability and better control response in a sport aerobatic model. A dual servo setup really is the way to go.

RE: Two servo ailerons
 

WOW! What a great forum. Thank you for all for the great information. Like so many things in the R/C world, two servo vs one servo ailerons are a very personal choice.

RE: Two servo ailerons
 

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RE: Two servo ailerons
 

In part of your statement above ("balancing the mechanical linkage and the servos through a match box"), Imay bewrong butI think you may be referring to having more that one servo per aileron, vs. one servo for eachside (L-R) that I think he is asking about in the original post, but Imay be off on that one, Iwas origianally thinking thats what he was asking about too.That being said- Ithink one servo per aileron simplifies setup and minimizes the chance forlinkage slop as opposed to a bellcrank setup, and reduces the possible flexing you can getin a strip-aileron configuration.

One correction though, the comment on"... anover powered dual servo, super fast aileron setup....". Just to point out, dual servo vs. single servo does not change the "speed" at which the aileron moves, the voltage does that. The servo, whether using one or two, still moves at the same speed, but you have more torque available per aileron. Same thing with using two servos on each aileron per side, no change in speed, only the torque to move (and hold) the aileron in place is what is being increased. Just my $0.02.

Dave</p>

RE: Two servo ailerons
 

I took his question as do I use one servo for both ailerons or one servo per aileron. I still stand by the one per aileron and the use of ball links. no slop that way and you have so many more options for setup.

Bob

RE: Two servo ailerons
 

I agree with sensei. I've had a couple of Chippes. They fly better with an aileron for EACH wing. Also, if this is your first "aileron plane," do yourself a big favor & park it for awhile like CampGems suggested. Get some stick time on a 4* or something like that. good luck !!

RE: Two servo ailerons
 

Use one servo on each aileron and one for each elevator. There will be no linkage problem and the reliability will be much higher. With today's smaller and lighter servos there's no reason to use one, unless you like the thrill of what happens when that one fails. Dan.

RE: Two servo ailerons
 

Absolutely.http://www.rcuniverse.com/forum/js/f...sn/thumbup.gif

RE: Two servo ailerons
 

Dave, you are correct. I got to thinking about that last night and decided I missed the mark with my answer. I always use a single servo per aileron. The single per wing did't pop to mind.

On the speed and such with two per surface. Most guys that go that route want the speed, so they use the fast servos and high voltage to get more power and speed. I just thought this was to big a step from no ailerons. Again, I didn't understand the question correctly and as a result gave a bogus answer.

Don

RE: Two servo ailerons
 

Well many years ago the servos were expensive, very expensive, even the low end low cost servos were expensive. So planes were designed to use the minimum number of servos to control the plane. So at the time a single aileron servo, etc. was the common approach. we would move the servos and electronics from one plane to the next to go flying. Few people bought extra flight packs for more than one plane.
But more recently servos became much more inexpensive. So the plane designs started reflecting that as well.

But for the advantages, a servo for each aileron control surface, means there is a short straight pushrod, so there is little to no play, little to no flex or sponginess to the control surface. Same thing for the having the elevator in two parts too, with a servo for each half. Even better is to have the elevator and rudder servos in the tail close to the control surfaces for maximum stiffness and least amount of flex and play too. So the plane flies better and tracks better through its aerobatic maneuvers.

RE: Two servo ailerons
 

Match Box?? I see nothing here about a match box. I do see him asking about the correct way, the two servos is just the easy way for adjustment. IF you have a nice computer radio then you do have a couple of things you can do with the two servos you can't do with only one. Because this is his first aileron plane I don't think he is going to be wanting to do any of the trick set up stuff. The plane was designed for a single servo, it has worked for a lot of years before the advent of the high end radio. If you know how to make the single servo linkage correctly there is no slop, there is no faster reaction. The system works great. I would be using two servos but that's just my choice, it's not really needed but as I have said, I really am lazy and have gotten into the habit of two aileron servos over the years. I would also be installing two elevator servos and a pull/pull rudder. Not needed, it's just how I do things. It's just an either or question without any really correct answer. If he only wants to use one servo it will work just fine. The plane was designed as a four channel and there have been thousands of them built as such. Either or, they both work just fine.;)

RE: Two servo ailerons
 

Thank you for showing this! I know exactly how to set up my P-51B with bomb drop now.

I also like the hand made belcrank. I'm going to do this as well.

Every post you have made I have learned something amazing from.

Brian

RE: Two servo ailerons
 

With one servo there is no redundancy. I have saved airplanes with a locked aileron, only because there was still one working aileron on the opposite wing. The pictures of the bell crank shown in this thread looks to be a good design, however I believe a poor execution in application, with the servo end not shown and another clevis connected to it, I see 4 connections that really should be ball links and a bell crank that should have ball bearings, not a sleeve and a bunch of clevises. That makes five places for slop per wing. I have manufactured bell crank systems for full scale applications and that is what I had to do to keep the system tight. Just saying... ;)

Bob

RE: Two servo ailerons
 

With the cost of a servo, and the capabilities of even a modest radio, I see no reason whatsoever NOT to put one servo on each aileron.