why do you need so many channels on a jet?

im planning on getting a good radio soon, and it seems most people use most of there 8,9 and 10 channel radios, how can you use so many channels on a jet?
its gonna be a while before i can afford jets, but for my other planes id like a quality radio, and id like to only buy once.
im thinking hightec, i love there products, but 7 channels doesnt seem like enough.

With the 12 channels that I have on the MPX Profi 4000, this is what I use (or have used on some planes):

1 left ele, 2 right ele, 3 left ail, 4 right ail, 5 left flap, 6 right flap, 7 throttle, 8 nose gear steer, 9 rudder, 10 retracts, 11 brakes, 12 gyro gain (if needed). I usually just mix brakes in with down elevator.

Of course, you don't need to seperate primary controls like this, it just helps with set up, redundancy, and gives you far more flexibility. Plus you do not require after-thought stop-gap devices like a Matchbox.

Channel 1 Throttle
Channel 2 Ailerons
Channel 3 Elevator
Channel 4 Rudder
Channel 5 Retracts
Channel 6 Flaps (or flaperons, two servo ailerons)
Channel 7 Wheel Brakes
Channel 8 Wheel steering seperate from Rudder operation
Channel 9 Speed Brake, smoke, or other BS
Channel 10 I have two rudder servos that are in two channels that can be mixed together. On the JR 10X system, you don't actually do this mix on channel 9 or 10 becuase of a refresh on the channel time difference, but it's certainly another channel option. This list could actually go further for instance
Channel 11 Canards
Channel 12 Independent Canards
Channel 13 Drop Bombs
CHannel 14 Independent control of gear doors?
Want a camera? Channel 15

Just depends on what you want to do. I could fly "jet" on four channels. Take a Top Gun F-15 Ducted fan with no remote control of the needle valve on the fan unit and no retracts. That's a four channel airplane all day long. Sky's the limit (pun intended) but actually limit is 10 channels on 10x and I heard that airtronics has a 13 channel, but take that as a rumor unless someone else chimes in as I didn't actually count the channels when I saw their top line transmitter. I just overheard someone say it was that many. As I posted this, I see someone else tackled the question and put things I didn't think of like Gyro Gain sensitivity, that's a good one. There really are a lot of options when thinking about channel usage and different radios. For starters, just go with a good JR 8103. That will go all the way through a good running Kangaroo turbine.

P.S. You can fly a jet on far less. Remember the original Kangaroo kit? It was marketed as being able to fly fine with 4 channels and three servos (elevon, elevon, & nose gear).

Ahhh...till ama got their hands in the pot.... Now your required to have rudders and brakes on turbines, not that it is a bad thing to have them

Todd

Todd, I've never been clear on the brakes issue from the rules/requirements standpoint. I've been told that if the jet does not roll at idle, brakes are not needed and that was the "rule" or "requirement". According to you what I've heard is false. After flying my ROO for the first time last week, I can see that it would be totally impractable not to have brakes on these turbine jets as runway length (and type of surface) would be a much larger issue without them. So have I heard fact or fiction?

I am not certain if the rules have changed or not, but I believe that it is still if it does not roll at idle, its OK without brakes.

Doc 513 (http://modelaircraft.org/templates/a...-files/513.pdf), page 2:


Gordon

While on the rules, My question is on an airplane that's not within the .9 thrust to weight ratio. If the jet does not have a speed limiter, does dialing the high end engine RPM down count?

Correct, if it does not roll at idle than you are not required to have brakes. A 12 lb turbine might would probably be ok but a 17+ lb tubine will require brakes on the roo. Cant imagine not having wheel brakes on any turbine jet unless you had lots of runway.....I am speaking in terms of paved here... doubt you would need brakes at all on grass

Todd

While brakes are not mandatory, they are necessary, keep in mind that many of us used brakes even back in the days when we were flying ducted fans. The brakes serve useful purposes even if your plane doesn't roll at idle.

I fly my 'Roo on a Futaba 8U just fine. I use the following allocation (i forget the actual channel numbers):

2 channels for elevons (would be 1 channel ailerons 1 channel elevators on non-delta aircraft).

1 channel for rudder

1 channel for throttle

1 channel for retracts

1 channel for speed brake

1 channel for wheel brakes

1 channel for turbine control

I'm going to use the same radio for my Panther, but that adds 2 sets of flaps and speed brakes to the mix. For that, I'm going to use the channel expander from JR to control the flaps and speed brakes from the same channel.

I find with all that going on, I don't really want yet another switch to activate - better to gang them on a single switch/slider/knob to cut down on operational complexity. True I don't have any additional channels to do things like setup the nosewheel steering different than the rudder, but there are other ways to do that, either with an after-market electronic box, or simple mechanical setup - just like in the old days...

Bob

it is all about flexibility. you can use a bunch of y harnesses to limit the channels, matchboxes as well but I think in the long run you would really be more satisfied with 8 or more channels. The 8103 or new futaba 8 channels would be suitable. after setting up one "advanced" aircraft on a computer radio, you will be adding channels/servos and throwing all kinds of mixes at your sport planes.

you can find some terrific deals on second hand JR 10sx and sxII radios. get a new battery pack and have it checked out.

I think some of it is over kill. Two channel for two rudder???
or two flaps ?. I have a f18 and jr10x tx elevator y rudder y

It could be considered overkill by some, and it is not necessary, but can make set up a lot sweeter, provide redundancy and offer other flexibility in exchange for the weight of a few more wires. For example on my HotSpot and my Boomerang, I will program the 12 channel Profi to allow me to mix the rudders so that they deploy outwards when the flaps are down providing more drag yet retaining rudder function. I also set it up so that the nose wheel (which is on a separate channel) is the only one affected by rudder trim. I have even considered setting it up so that flaps act with a little aileron movement for redundancy or more control at low airspeeds. I have not yet tried this. Could try the same with elevators. Since the MPX has the capability, why not use it?

Then you have either a reversing servo on one rudder, or you have one rudder turned around and have one control rod longer than the other. Clearly there are mechanical ways to limit number of channels. I don't think anyone here is advocating "move to more channels". Just answering what you can do the more channels you have.

When will a 12 channel Multiplex be available in a normal form factor (like a thumb flier is used to)?

Thanks

Matt

I really think that if you guys would try it, you'd have no issues with the Pizza Box. I thought the same things before I flew with it, but obce I tried it, it was a non-issue. And I fly thumbs only. But that's OK Matt, cause the Royal Evo 9 ch & 12 ch is a Japanese/Americanski styled radio case and is already out in Europe and should be here soon too.

When I had my Roo, I used my 8 channel, I ended up upgrading to the PCM10SXII because of some of the mixing features, and the extra channels. In my exocet I now use

(not in receiver order)

1. throttle
2. Ailerons (they are on a Y harness)
3. Left Flap
4. Right Flap (one could be eliminated with a reversed servo, but I like the flexibility of being able to adjust the throw and speed of the servo's in case one is a little different from the other, though I haven't had this problem with the digital servo's)
5. Left elevator
6. Right elevator (same deal as above, could be eliminated)
7. Rudder
8. nose wheel (could also be on a Y harness, but I didn't worry about it
9. Retracts
10. Brakes

Some of the things I really prefer in the 10 channel is the servo speed adjustment. When I had my Roo, every time I deployed the speed brake with the 8 channel, and it popped down fast, the jet would balloon horribly, with the 10 channel, I slowed it down, and it got rid of the ballooning for me.
I like the touch screen and the entire menu being visible better as well. that is just convenience to me.

Go here for Royal Evo info:

http://royalhobby.com/royalevoradio.htm

I, and the other 8 people in my club who use Multiplex, are all thumbs on top fliers. The only people we know who use trays and finger and thumb are people with Futaba.

The notion that the wide Multiplex are not suited for thumbs, or have to be used with trays, is just myth. The wide shallow box fits into your hands more naturally than the narrow deep Japanese boxes do. Since Futaba/JR can't compete with Multiplex Profi, especially the 4000, for flexibility, programmability, and ground-breaking features, they have to rely on the spread of misinformation.

Harry

Why not cut through all this crap and just go with the Rolls Royce solution....Graupner MC24!!!! Every radio you'll ever need!

Cheers,

Dick
England

"Why not cut through all this crap and just go with the Rolls Royce solution....Graupner MC24!!!! Every radio you'll ever need!"

Well, primarily because if you want the Multiplex's unheard of range, 12 fully proportional channels here in the USA and IPD receiver technology, you'll still need the Ferrari, the MPX Profi! Why settle for the Rolls?

Heheheh....thought you might bite, Mark!!!!

Cheers,

Dick
England

Bite? I swallowed the hook!