How many channels beside the usuall 4 we really need?

A 6, 7, 8 or 9 radio Tx

It depends on how involved you get.

In addition to the standard 4, there's flaps, which are common, retracts are also used pretty regularly, how about a smoke system, or lighting. If you're using seperate aileron servos it's nice to have an extra channel to plug one into.

I've also seen seperate channels used for sliding canopies and rotating gun turrets on scale bombers.
Dennis-

My 2M pattern ship uses 6 channels, My 35%'s use 9 channels, even my small Stream 50 uses 6 channels. In fact, the only plane I have that uses just 4 channels is an indoor electric.

Helis really need 5 channels. A good sailplane with flaps, spoilers, crow mix, etc will need at least 7 channels. Talk to pilots who fly turbines and they'll tell you 12 channels aren't enough.

You can fly lots of planes with just a 4 channel radio. You can even fly dual aileron/elevator planes with a y-harneses, etc. But more complex planes really benefit from (or may even dictate) more channels. Much easier to set up, more flexible, not to mention the higher channel radios have more mixes.

For the average powered sport pilot, 6 channels is probably all they will ever need. Throttle, L-aileron, R-aileron, elevator, rudder, that's five, then six could be used for flap or gear retract or second elevator servo or smoke or etc.

Cheers

Well trying to fly a helicopter on a 4Channel would be a hell of a task.

For Planes though.

I always run my Ailerons on seperate channels.
A couple of my planes have retracts.
So there we have 6. That leaves me 1 or 2 channels depending on the radio I am using at the moment. Smoke systems, Co-Pilots, bomb drops(my next project), flaps, etc.

Channels get eaten up pretty quickly. I find that even my 9C may not be enough for some of the things I want to try.

Newbie, so have pateince with the question.

I noticed people talk about using a seperate servo for each aileron.

Wouldn't one servo be enough by setting it up so as one aileron is lifted the other side lowers.

Is it for redunacy? Can use a smaller servo if only pushing one aileron? Safety?

And if you did use two servos for ailerons, is it possible to run them off the came channel? Can you run 2 seperate channels off the same contol input (stick)? What would a Y-Connector be used for?

Sorry if this has been covered before. If it has, just point me to the link and I'll go look at it.

Thanks

Good questions
I think I can answer them.

On smaller planes you can run Both Ailerons off of one Servo.
In fact every trainer I have seen has been set up this way.
However this is not practical on larger planes or on planes where the ailerons are far out on the wing. A Mustang for instance.

on a 3D plane or a .60 size and up plane, you want the maximum speed and reliablility possible. This means using a servo for each control surface. And in some cases you will even have two or more servos per control surface.

You can run both Aileron servos off one channel with the use of a Y harness. These cost about 10 bucks and are exactly what they sound like. They split the one input into two. One Servo will also be reversed off of a Y harness. Very important for Ailerons

Now I prefer two aileron Servos and two channels. My reson for thisis simple. You have much more percise control over each aileron. You can make minor trim adjustments to one without having an impact on the other. And you can mix them to move up and down at different rates or with more or less travel independently. Something that can't be done with a Y Harness or single servo setup.

All computer Radios are set up to allow you to run two aileron Servos. In the case of my 9C it is channels 1 and 6. ALthough I believe you can switch the second one to channel 7 instead(or maybe 5) Either way there you go. I hope that helped.


Opps

Theoreticly you could use a smaller Servo for the Ailerons if you used one servo per. However this isn't common practice except in thin winged planes. For instance my .40 Sized Pits has a wing that is to thin for a standard servo. So I use Hitech HS81s They are smaller but offer the same ammount of power as most full sized.

There are two basic ways to set up ailerons.

1/ Using one servo, mounted in the center of the wing, with each side of the two arms on the servo activating each aileron. One goes up while the other goes down. This takes up just the one channel (normally channel 1)

2/ Using a servo in the middle of each wing half, with each aileron being actuated separately. This set-up uses two channels (normally channels 1 and 6 )

They are both good, but the second choice (using two servos) has the advantage that you can program the radio to operate the ailerons as flaps too, by moving them both down together, as opposed to one up and one down.

Hope that helped!

-David C.

Thank You

OK. I understand the one servo and y-harness but the two channel thing is whipping me.

If you control each aileron sepertely, what are the control inputs for each one from the Xmitter?

I dont fly yet, but am learning so bear with me.

If I recall the Xmitter input to the aileron servo is the left stick (Right and left) which would be transmitted on CH1. Can both servos (each servo having it's own channel) be controlled from this one input? Is this part of "programming" the box to allow this?

If this is true, then that is pretty darn cool!

My only exposure to a servo setup is a PICA Spitfire (1/6) which only had a 1 servo setup (centerline) for both ailerons. It seemed to work fine.

Thanks!!

>but the two channel thing is whipping me.

It's the way the radio microprocessor ("computer") is set up. From the programming menu you select the "dual servo" option and plug one servo into channel 1 and othe other into (typically) channel 6. The radio has a programmed mix to operate one aileron servo from channel 1, the other aileron servo from channel 6.
No understanding needed, it's just the way the transmitter is designed.

--Bill

Not true. Both servos will turn the same way. You must hook your push rods to the opposite side of each servo to get the desired opposite movement. If you need to reverse the direction of the servos (as for elevators) you need a reversing Y Cord (if you don't have a computer radio)

Also not true. You can get differential from a single servo by rotating the 6-arm wheel 30 degrees (45 degrees for a 4-arm wheel) and connecting to the two parallel arms (See Pic).

In a 2 servo set-up, you can either operate them with one channel, using a 'Y' branch lead (the Y branch does the reversing for you), but you lose the ability to control each separately, or using two entirely separate channels , in which case the joystick (the right one, which also operates the elevator) moves the servos in opposite directions as it is mixed that way in the transmitter.

Clever eh?



-DC

Well, that should confuse the poor guy!

-David C.

Swager, ignore David Cutlers comments, I think he is just toying with you as nearly all his advice is either totaly wrong or partially wrong. Minni Flyer is correct.

MinnFlyer you may be correct on the Y-Harness. I will have to check that tonight when I get home.


And I should have been more clear on the differential. I was tankling aobut mixing it in the radio and tying it to a switch so that you can adjust it in flight. I was actually trying to figure out how to do it when I saw this post.

As Minnflyer said, Y harnesses typically do NOT reverse one aileron. But there are Y's made that will reverse one servo.

Also as Minn so nicely illustrated, setting up mechanical aileron differential is possible, and not difficult. I usually have my student(s) set up the trainer this way.

Ailerons are USUALLY on the right hand stick (mode II).

While there are other reasons, the primary reason for using seperate servos for ailerons is so you can program in 'Flaperons' on your computer radio. (The ailerons work as both, ailerons and flaps.)
Dennis-

Interesting. Which advice in particular?

-DC

I would suggest you look through the thread again. Minnflyer's comments were addressed to somebody else, so there hasn't been a contradiction of what I said from that quarter. Your comment about him being correct, and me not is therefore completely illogical.

Could you now retract your comment now please, before the poor questioner is confused even more?

Thanks

-David C.

p.s. Also you got Minnflyer's name wrong. You're not doing very well today eh? Never mind, we all have off days

Both David Cutler and Minnflyer's comments in this post are correct. I've never met either, but have sorta known them for over a year via RCU. The are both knowledgeable and offer good advice. Minnflyer pointed out a way to mechanically set up differential. But with two aileron servo's, it is much easier to do in my opinion by programming the radio, as David pointed out.

Swager: With a 2 channel aileron setup, you still control both servos with one stick on the transmitter. The radio just "knows" to run two servos from that stick. It "knows" because you program the radio as such. With a one servos setup, the radio "knows" just to run the one servo, again because of how you programmed the radio. Hope that helps.

Davids comments were correct (as usual) The only thing he was wrong about was his comment about "Y" cords reversing the servo.:

A standard "Y" cord does not reverse the servos. You do not WANT to reverse the servos for ailerons. In the pic below, you can see that all 3 servos are going the same way to achieve the desired results.

Minnflyer checked my Y-Harness last night. I have one that reverses a servo and one that does not. Both were given to me and neither have ever been used in a plane. I am assuming the one is set up to reverse the servo for use with flaps or somethign similar.

Correct. If you have two servos for flaps or elevators, you would (in most cases) want them to be reversed.

Thanks Minnflyer.

Yep you are right, of course, about my slightly less than accurate comment about the Y harness reversing the aileron servos in this context.

I remember when I was writing it, that I didn't want to make my response too complicated for the questioner, and wanted to let him know that, when a reverser is needed, as in, for instance, dual elevator servos (because the servos themselves are mirrored and therefore are already reversing, and needed reversing back to unison again) it is available. (See? I can't say it simply!!!)

Actually, it's a debatable point anyway, as the geometry of mirrored servers should be considered so that their movement not only have the same end points, but also move in exactly the same way throughout the range, but that debate is definitely the subject of another thread!!

<argh!>

Anyway, thanks for the support. I was beginning to think I was going mad!

-David C.

phew!

Thanks Monkeyboy.

I was beginning to think I was going mad myself! See my response to Minnflyer's message.

-Davd C.

Can I ask how many channels does your Tx has?

And how many channel do you guys think is the perfect balance(price-channels)

Not that it really matters, I use a Futaba 9 ZAP. It has 8 fully proportional channels and a 9th on/off channel (for on/off tasks like smoke or retracts.)

I'm not sure if there is a "balance." If you need more channels to fly the plane of your dreams, you need the channels. If you want to fly a heli with collective pitch, you really need 5 channels, etc.

Like I pointed out before, probably most planes can be flown on a 4 ch transmitter. You may have to use a Y-harness of some type, but it still can be done. Adding an additional 2 channels really simplifies things on planes that use dual ailerons/dual elevators. And, you'll need an extra channel if you want flaps or retracts or smoke or what ever.

The "average" RC pilot probably uses a 4ch or 6ch radio as this is all they really need. However, what sells many on the higher channel radios isn't actually the channels. While the pilot may make use of the extra channels, it is the advanced programming features typically only found in the higher channel radios that is the main selling point.

For example, what sold me on my 9ZAP wasn't the 9 channels. I selected the ZAP because of the flexibility in the radio and a programming feature called conditions. The 9 channels however are nice... sometimes I wish I had more, but it was really the mixing the pushed me to buy the radio. I ran out of mixers on my 6XAS before I needed a 7th channel (6XAS has 6 channels.)

Cheers