What are the different types of Radios?

[Ken Cz]

I have searched the Web and I cannot find a site that explains what the different R/C radio types are.
For instance, what is FM vs PCM?
Some radios are only one channel, some appear to work on multiple selectable channels and other sound like they can be dialed in to any channel.
What is 'computer radio' ?
I bought a newbie book but it does not spell out the difference.
Right now I have an electric trainer (cheap radio in kit) but over the winter I would like to get better equipment.
I will fly electrics but would like to move to gas/nitro in the future.
I'm confused! Help!
Thanks,
Ken

[aeajr]

Which radio should I buy. All new flyers ask this question.

How many channels do I need? You will get many opinions.

First it is important to realize that you should be able to fly almost any
plane with a standard four channel radio. That is enough to control rudder,
elevator, ailerons and throttle. If this is a sailplane, then four channels
will allow you to handle R/E/A and flaps or spoilers to help with precision
landings. With four channels you can fly an indoor plane, an electric park
flyer, a sailplane or a giant high powered plane. Jets might require more
than 4.

With a 6 channel standard radio, with no computer mixing, you can add
control for landing gear and flaps to the R/E/A/T functions mentioned above. However
you can't mix them together in the radio. You have to do it manually. A
coordinated turn requires you to add rudder to the ailerons. When you
deploy flaps you will have to push and hold the elevator forward to keep the
plane from ballooning up. If you deploy spoilers, then you probably need to pull and
hold some up elevator or the plane will go into a dive.

These are complex things to handle. I know I could not get a good balance
between the up elevator and spoilers when I was trying to do them manually.
Most people find them easier to do with a computer radio which can
coordinate more than one servo from a single input. It made a world of difference for
me.

Computer radios let you do things that a standard radio can't do no matter
how many channels it has. So we start to see that our answer to, "how many
channels" it is more than just the number of channels.

If you have more channels AND a computer radio, you gain flexibility. For
example, you can put two servos on the ailerons and control them
individually. That is something the 6 channel standard radio can not do. It has enough
channels but it can't mix them the way a computer radio can. If you are
going to beyond the standard 4 channels, you should be looking at a computer radio
where you can really take advantage of the extra channels.

Here is a typical channel breakdown, how many and what they are used to
control. These apply to electrics, glow and gliders.

Rudder - 1
Elevator - 1 or 2
Ailerons - 1 or 2
Spoilers/Flaps - 1 or 2
Motor 1
tow hook 1
landing gear - 1

That makes 4, 5, 6, 7, 8, 9 or 10 depending on what kind of plane you have.

Could you use 12? Sure, if you have the money? Bomb drops, smoke, lights,
and other stuff, all take channels.

I am not pushing a given number of channels, just trying to help establish
what they are used for.

In my opinion, many sport flyers will be well served with a 5 or 6 channel
entry level computer radio, like the Hitec Flash 5SX or the Futaba 6EXA,
that can handle two aileron servos with some special mixing. They can
automatically mix rudder with ailerons for coordinated turns. They can
usually add some elevator compensation mixed with the flaps or spoilers to
keep the plane level when the flaps/spoilers are deployed. These may be all
the channels and all the mixing many flyers will ever need. These entry
level 5 and 6 channel radios may not be able to do all of these things at once,
but they can do some of them and you can choose which is the most valuable for
you.

If we step up in computer sophistication with 6 or 7 channels we find radios
like the six channel Hitec Optic 6 or a seven channel Futaba 7C. I consider
these advanced sport computer radios. With this class of radio and channel
count, you have about all you need to fly almost any sport plane. The Optic
6
and 7C can do some pretty sophisticated mixing. More importantly they add
more custom mixing that allow you to select what you want to mix and can
handle more mixes at once.

For most of us, a six or seven channel advanced sport computer radio would
be all we would likely ever need. You typically don't have spoilers and flaps
on
the same plane, a motor and a tow hook then six or seven is enough. While
landing gear is very rare on sailplanes it is common on power planes. Most
sport planes and mid level sailplanes don't need two flap servos. So six or
seven will still usually do it.

Four servo wings

Here we see radios like the Hitec Eclipse 7, the Futaba 9C, the Multiplex
Evo 9 and other advanced radios. I call these midrange radios which handle
complex planes and may carry you into serious competition. These have seven
or more channels but more importantly they have much more powerful computer
software to handle all the servos and how they are mixed and how the mixes
can be changed while the plane is in flight.

If you step into the world of full house sailplanes, now you are into some
complex mixing requirements as much as the number of channels. These
planes have 4 servos in the wings which must each be controlled on their own
channel. That's four channels. Rudder and elevator and you have a full house
sailplane needing 6 channels and sophisticated mixing to allow the pilot to
reshape the wing while the plane is in flight. Normally you want at least 7
channels for a full house sailplane as some of them have motors for
launching or tow hooks for being towed up into the sky.

For aerobatic power planes, you often add two elevator servos that can
follow the ailerons in their function. Each needs its own channel so now we are up
to eight channels and, again, sophisticated computer mixing to fully utilize
all those servos. For the aerobats you may want a nine or more channel
radio so you can handle smoke, lights and other things.

It is worth noting that we are not yet into the professional radios yet
which can have 10 or more channels.


Summary

So, back to the original question of how many channels. The answer is not
as simple as we might have thought. Four is adequate to fly. A computer radio
with 6 can do a lot. I feel 7 channels on an advanced sport radio should
carry most flyers for most or all of their flying career.

If you have your sights on full house sailplanes or advanced aerobatics then
it better be at least 7. For people with their eye on scale sailplanes, I
would say 8
or more channels and a very sophisticated computer radio to
handle it all.

This has been a lot to digest.

What you need to know about receivers:
http://www.rchangout.com/forums/radio-electronics-motors-and-accessories/t-what-you-need-to-know-about-receivers-12151.html

[aeajr]

Here are some additional resources:

For beginners - Computer Radios and Surface Mixes
http://www.rcgroups.com/forums/showthread.php?t=157053

What radio should new flyers buy
http://www.rchangout.com/forums/showthread.php?t=6245&page=1&pp=12

Range Checks
http://www.rchangout.com/forums/showthread.php?t=7753

Choosing a Sailplane Radio - What to Consider
http://forums.flyesl.com/topic.asp?TOPIC_ID=223

DX6- The Perfect Parkflyer Radio
http://www.wattflyer.com/forums/showthread.php?t=2077

[Ken Cz]

Thank you for all the valuable, experience based replies. They are extremely helpful and in most cases the only place I can find answers to questions like these.
You are true gentleman and a tribute to the Sport!
Ken Cz

[aeajr]

Ken Cz,

Glad I could be of assistance.

[kingsnake93]

I have the Dx6

[aeajr]

Bottom line is:

If you are planning on flying parkflyers, small electrics ( up to about 66 inches), hand launched gliders, Discus launched gliders or balsa or foam slope or thermal gliders up to about 70 inches, like the Easy Glider, I would strongly recommend the Spektrum DX6. If you want to fly small electric Helis, the DX6 would also be a perfect radio. For a lot of people this is all they will likely ever need. With the explosion of planes in these classes, there are a LOT of planes to choose from.

If you are going to fly gas or glow airplanes or helis, or larger electrics or gliders the DX6 is not appropriate. Or, if you plan to get into advance aerobatics, then I would recommend something else based on your goals and your budget.

[aeajr]

Spektrum has now released the DX7 which is a step up from the DX6. It is rated for any size and any type plane or Heli. So 2.4 GHz has not gone across the board.

The only things it lacks, in my opinion, is some of the complex surface mixes that sailplane pilots like and the ability to address all 4 wing servos on on individual channels. You still need a Y cable for the flaps. This would limit, for example, your ability to fully utilize the quad flap feature of the Ultra Stick, for example, however that is not a problem for many flyers.

They also released two new receivers. A new micro receiver for the DX7 which is even smaller than the receiver available for the DX6, which is also half the weight. For the larger planes they have a two part receiver that gives you the full range you need for these big planes.

At $350, it is clearly in the upper range of the sport radios, but an excellent choice for a very wide range of flyers.

[Ken Cz]

Hi,
I just picked up a DX7 with 4 digital High torque servos ($30 ea if purchased sererately) and the full size/dual receiver for $309. Includes both the TX (1100 mh) and Rx batteries.
My thought was that it is probably the only radio I will ever need as a Sport Flyer ( still working on it! :eek: )
Ken

[aeajr]

How are you doing with the DX7?

[Ken Cz]

Working good now.
Took me a while but now I am pretty comfortable with all the basic functions and understand what I am doing.
Even patched it in to my GP 3.5 sim and use it for practice during the cold Michigan winters ( about zero as I write this).
Still not too sure on setting up a plane with flapperons and the how the flap function plays into it but I guess it just takes time.
Biggest dissapointment with the radio is the owners manual - it seems to assume that you know what all the functions are and how they interplay with other functions. Just not very discriptive. Things like 'binding' the receiver to the TX took a lot of guess work ( poor photos) and several calls to Horizon. All in all, I am happy with the unit- it appears to be made by JR as the outer case is exactly like one thier models.

Thanks for all the help!
Ken :D

[aeajr]

According to JR, they do not make the Spektrum radios. I think that Spektrum buys the JR Shells and guts and adds their on RF/transmitter sections to them. So it may be a JR transmitter case and guts but it is a Spektrum transmitter.

JR does not service them.