What kind of radio for a new flyer

[aeajr]

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

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

And, you will get a debate on whether your first radio should be a standard radio or a computer
radio. What's the difference?

First it is important to realize that you should be able to fly any plane on 4
channels. That is enough to control rudder, elevator, ailerons and throttle.
With that you can fly an indoor plane, an electric park flyer or a giant high
powered plane.

However, with more channels you gain flexibility. For example, you can put
two servos on the ailerons and control them individually. You can operate
moveable landing gear. And, when it comes to gliders/sailplanes you are
likely to do more surface mixing than on power planes, so if you into
sailplanes and plan to fly full house sailplanes, you typically want more than
4 channels so you can do that fancy surface mixing. The club wizards
recommended at least 7 channels for full house sailplanes.

Here is a typical channel breakdown. These apply to electrics, glo and
gliders.

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

That makes 5 or 7.

Could you use 9? Sure, if you have the money?
How about 12? Sure, if you have the money?

I am not pushing a given number of channels, just trying to help establish
what they are used for. In my opinion, most sport flyers will be well served
with a 5 channel computer radio and be able to do what they need to do for
years. Bump it up to 7 channels and you have about all you need to fly almost
any sport plane without feeling you are short channels. If your plane has
bomb doors, fires rockets, ejects pilots, and stuff like that, 12 might not be
enough.

For the rest of us, why would 7 be enough. You typically don't have spoilers
and flaps on the same plane. A motor and a
tow hook would not likely reside on the same plane either. While landing gear
is very rare on sailplanes it is common on power planes, but then you really
don't need two flap servos because power planes don't usually do the kind of
complex flap mixing that sailplanes use. So 7 will still usually do it unless
you are into really complex planes or really advanced competition.

[aeajr]

Computer radio vs. standard. Here is a more concrete illustration of the value
of computer radios.

There is about a $45 difference between the Hitec Laser 4 standard and the
Hitec Flash 5X computer radios. What do you get for the extra money?

Channel 5, the retract channel. Now you can fly a plane with retracts.
That's cool, but perhaps not all that important to you.

Mixing is the real value here. Let's do a targeted discussion on mixing.
Let's focus on aileron mixing only.

You are flying your 4 channel glo or electric plane. You use R/E/T/A - rudder,
elevator, throttle and ailerons.

Standard 4 channel flies that fine. No issues at all.

Now, put it on a Flash 5X or many other computer radios that have at least 5
channels.

Put in two servos for the ailerons and assign them to different channels.

Under normal flight conditions the ailerons work exactly as before, but using
two servos; No difference.

You are coming in for a landing. You turn on final approach to the runway and
line up for the center line. If you had flaps, here is where you would use
them, but your plane does not have flaps.

You level up the wings. At this point, you flip a switch on the flash 5X and
your ailerons just became flaps. You can still use the same stick and you can
still use the ailerons to bank/steer the plane, but they are both turned down
now
so you will get a different aileron response than normal..

This is the flapperon mix. You now have the ability to come in much slower
which gives you a much softer more controlled landing. Flaps lower the stall
speed so you can fly at much slower speeds without stalling. Very useful!

That is surface mixing and that is what a computer radio can do for you.

Getting the idea?

Gliders. same idea - focus on ailerons.

Your next glider has ailerons. You can do the flaps as above, but you can
also flip that switch and make them spoilers.

Spoilers spoil the lift of the wing and help you bring the plane down in a
level flight path for a slide in on the belly landing. Without spoilers, if
your glider has too much energy and you are committed to landing, you
have to put the nose down which can result in a hard landing, or "glide it
out", if you have the room,
until it comes to a rest and then take the long walk. You can't hit the gas
and go around again, you have to come down somewhere. Spoilers make it easer
to control where.

Gliders have such efficient high lift wings and such light wing loading it can
be hard to get them down, especially in gusty conditions. Really! You have
to see it and feel it to understand. It is amazing!

I have one glider that has ailerons but no flaps or spoilers. I will be
setting up flapperons AND spoilerons on that plane, if my Hitec Prism 7X will
allow me to set up both, and will use which ever is most appropriate for that
landing situation.

That is what you get for your $45. You get flaps and spoilers on planes that
don't have them and you can turn them on and off at will.

There are a lot more mixes. A lot, but hopefully you can relate to this
example.

[aeajr]

Here is a short discussion on surface/channel mixes based on a 7 channel
radio.. I invite others to
clarify or correct my comments and add where these mixes, or others, are used.

First, there are three primary control surfaces:

Elevator - Pitch or attitude control - nose up and down - usually part of the
tail

Rudder - Yaw control - nose left and right - usually part of the tail

Aileron - Roll Control - usually on the trailing edge of the wing

If you are not familiar with these surfaces, this site might be helpful:
http://www.flyingsites.co.uk/newcomers/controls/primaryflight1.htm

There are two secondary control surfaces, usually used in landing but not
always.

Flaps - These are a moveable part of the trailing edge of the wing that you
lower to slow a plane while adding lift to the wing and lowering the stall
speed.

Spoilers - Typically used in landing gliders or sailplanes, these are on the
top of the wing. When these are raised, they reduce, or spoil the lift of the
wing in that area. They can help slow a plane down and raise the stall speed
of the plane causing it to descend from lack of wing lift. These can also be
helpful in getting sailplanes out of strong thermals.

Surface mixes

V-Tail mix - comes from the fact that on a V-tail plane, you do not
have a separate elevator and rudder. The two V surfaces are mixed to perform
these functions.

If you hit up elevator, both move up. If you hit right rudder AT THE SAME
TIME as up elevator, the tail surfaces move some more moving the nose to the
right as it moves up. So you have mixed the rudder in with the elevator
input. V-tail mixing. For this reason, the surfaces on a v-tail plane are
called rudervators; rudder/elevators

Elevon Mixing - Typically used on a flying wing, like my Electrajet or a ZAGI,
they do the same type of thing only this is elevator/aileron mixing; elevon
mixing. The surfaces are referred to as elevons.

Many of the newer non-computer radios include v-tail and elevon mixing now
whereas it used to require a computer radio, or the addition of a special
mixing device in the electronics package.

There are other mixes as well. Using a computer radio or a dedicated mixing
device, you can coordinate all types of combinations for different effects.
These are often controlled with the switches on the top of the radio. Flip a
switch and you will get a different behavior from the control surfaces for the
same stick input.

Coordinated Turn - On power planes and on sailplanes, it is normal to add
rudder to aileron input. This is called a coordinated turn and is common to
do manually on non-computer radios, but computer radios can be set up to do
this automatically.

Coordinated Flaps - You can add the flaps to the ailerons so that the flaps
move with, and coordinate with the ailerons The flaps become extensions of
the ailerons for more control surface movement. This takes 4 servos, usually
in the wings. I think this is called aileron/flap coordination, or
coordinated flaps.

Likewise, the ailerons can be made to follow the flaps to multiply the effect
of lowering flaps. This requires a minimum of three servos, two on the
ailerons and one on the flaps.

Flapperons - Ailerons can act as flaps, if you don't have flaps, for landing
control. These are known as flapperons which is a change in assignment of the
surface from aileron behavior to flap behavior. This requires two servos for
the ailerons.

Differential Spoilers - You can take spoilers, these reside at the top of the
wings, and tie them to the aileron function. Now you have your spoilers at
different heights causing a roll effect. Not as effective as ailerons, but it
might be useful as a landing aid. To do this your spoilers require two
servos instead of one.

Camber Changing Trailing Edge - On sailplanes they use a mix where the
ailerons follow the flaps to move the whole trailing edge down for a camber
changing effect, since you essentially change the shape of the wing while it
is flying. By lowering the flaps and ailerons together you create a more
under cambered wing. This changes the glide characteristics of the plane.
Again, a minimum of three wing servos is needed to do this. I don't think
this is used on power planes. I don't know if you would ever move the trailing
edge up for a change in top airfoil profile.

Sailplanes also have a set-up called "Crow" where both ailerons go up while
the flaps go down. This really slows the plane down to help with precision
landing.

With the right computer radio you can mix all kinds of combinations. Flaps
tied to ailerons with rudder input would be a flapperon coordinated turn, I
guess.

Imagine the fun you can have changing between different launch modes, or
moving from launch to
standard flight mode to several enhanced flight modes, to a camber change to
3 different landing modes.

Think of how long it would take to set this all up for each plane.

Think of all the mistakes you could make with the flip of a switch!

Well, this is what computer radios do. Not all computer radios can do all of
these mixes. However when you read the spec sheets, they will usually list
Fixed Wing Mixes and Sailplane Mixes. Some also do mixes for helicopters.

You will also hear about mode 1 and mode 2. In North America, Mode 2 is the
standard. More on modes can be found here.
http://www.flyingsites.co.uk/newcomers/controls/radiomode.htm

Is this a fun hobby, or what?

If all this talk of sailplanes has you interested, you might find this thread
of value:
http://lisf.proboards13.com/index.cgi?board=general&action=display&num=1070740602

[nitrohalic]

does a futaba t6xa have most of these features?

[highwindflyer]

The Futaba 6xas is a computer radio but it comes with the FM receiver. You must update it with the PCM receiver in order to use the computer functions. With the PCM receiver, you can add TWO (2) additional mixes to the following preprogrammed mixes:
For Aircraft the extensive preprogrammed mixing features include:
Flaperon Airbrake
V-tail Elevator->flap
Elevon Flap-> elevator
For Helicopter features include:
Hovering throttle Hovering pitch
Revolution mixing Idle up
Swashplate type selection Throttle hold
Rudder offset Pitch rates, normal, idle up, hover
The T6XAS may be used for sailplane, but Futaba recommends the
8UAPS radio FUTJ81**, specifically for sailplanes.

Hope this helps.

Highwindflyer

[Rodney]

I think what hiflyer means is it comes with a ppm reciever. Both PCM and PPM are FM receivers. Wether you use PPM or PCM the computer mixes are the same.

[aeajr]

Hitec Flash 5X and Futaba 7C are also good radios to investigate

[aeajr]

Here is an indepth article on comptuer radios that may be helpful:
http://www.rcezine.com/cms/article.php?cat=&id=65