What is the max number of channels generally needed for giant scale?

[David Shriver]

The matchbox is basically a really fancy Y cable. It allows you to match throw and direction of 2 servos. If you use it on elevator you would plug the matchbox into your elevator channel on your rx. Then both elevator servos plug into your matchbox.

 

[sweetpea]

I prefer the Smart Fly Equalizers over the matchbox. Finer adjustments possible. Additionally the matchbox has its own battery input (Can't remember if the Equalizer does). This is an old holdover from the days of NiCad when more power was necessary on ganged surfaces. Not many folks put batteries on it anymore with LIONS/LIPOS/A123's

8-9ch is typical.

1 throttle
1 kill or choke
1 smoke (optional)
2 aileron (2 servos per wing, so use a matchbox/equalizer per wing)
2 elevator (1 per elevator, let radio do the work)
2 rudder (matchbox/equalizer per wing)


I normally just get the SF EQ6 for this setup. Comes with the optic kill and adjustments for every channel so you can gang servos on any surface.

The reason you setup the way I have above....

1. Left and Right ailerons can go on 1 matchbox/equalizer but you lose the ability to adjust differential from the radio or fine trim. You would have to do it from the equalizer/matchbox which is time consuming and not possible during the flights

2. I prefer my elevators to be on their own channels. This way you can ensure deflection is correct when doing the Goldberg trim sheet. Sometimes ARF surfaces are not quite straight and fine tuning is needed in flight.

3. My P-47 uses a EQ6 and I put optic kill and choke on the same channel. I have it where it works great, I can kill the engine with optic then the choke will close. Took a while to set it up correctly though.

 

[Jetpainter]

You can also use one Booma RC IM22 instead of two Matchboxes.

 

[wfield0455]

While You've received a number of perfectly valid replies, personally, I think the answer to the question of how many channels are needed for giant scale is; "it depends entirely on what you're going to fly"... If you want to mainly fly Aerobatics planes up to say 40% size, with the appropriate on-board equipment (power-safe receiver, smart-fly, matchboxes, etc) you will be just fine with your DX9 as others have pointed out. However, if you're interested in complex, large scale aircraft or jets, with twin engines, flaps, retracts and gear doors, air brake, slats, sliding canopy, light systems, etc. It becomes pretty clear that the limit to the number of channels needed is your imagination and just what level of detail you want to achieve. Personally, for my scale planes, I find that 12 - 14 channels is pretty adequate but I don't go crazy with light systems, etc. I've seen a number of guys build top gun quality, highly complex, VERY large jets that are controlled with a 12 channel transmitter. It all comes down to how complex do you want to get and how much money are you willing to spend...

Wayne

 

[jamesrxx951]

The matchbox is basically a really fancy Y cable. It allows you to match throw and direction of 2 servos. If you use it on elevator you would plug the matchbox into your elevator channel on your rx. Then both elevator servos plug into your matchbox.

Along with this, you still need to have a good mechanical match. You can match end points and center but if the mechanical is not matched you will have binding in the mid travel on ganged surfaces.

 

[Daytonarc]

I tried to look up some info on Matchbox, but I didn't find a whole lot. How is using a JR matchbox different than using something like one of the bus protocols? Does the Matchbox let you mix different servo brands in the same system (maybe one brand for the throttle and another brand for ailerons)?

Do I understand it correctly that, using the 7 Channel example above, if I used 2 Matchboxes (one fore aileron and one for elevator) that I would only use 5 channels on the transmitter?

A matchbox allows you to use 2 to 4 servos on one channel. With it you can set the endpoints and direction of each of the servos individually to match the throws as needed for all servos being used on the channel. This is to use multiple servos on the same channel for aileron, elevator or rudder. I would not advise trying to use different types of servos on the same channel.

 

[Xpress]

9 channels seems to be sufficient for most any giant scale airplane up to 40% if you want a dedicated channel for every servo. Technically, you could get away with using a simple 5 channel radio and a servo matching system, but you'd be limited with the functions you can use.

There's guys in my club flying 40% airplanes with only 9 channels:

-4 Aileron servos
-2 Elevator servos
-2 Rudder servos
-1 Throttle servo

The same setup can be used on a 35%. So, if you ask me, I'd say 9 channels is the minimum required, but more channels is always nice.