Let’s first assess where you stand with your flying skills:

Unless you’re the rare 1 in 100 for which RC flying is drop-dead easy stuff, you’re now able to take off, do some simple aerobatics – such as loops and spins – land and you’ve pretty well internalized how to control the plane when it’s flying away from you or toward you without thinking about it. Most likely your trainer is rudder and elevator only – no ailerons.

In short, you’ve got the basics pretty well nailed down. However, you’ve done this with a plane that’s built to be very forgiving – more than likely a high wing trainer. These are configured to be fairly “goof-proof” – they will tend to self-correct if you let the sticks go, fly slow enough to allow corrections in a second or two to take effect and generally be very tolerant of over-correcting the plane.

So what’s next? A WARBIRD! Can’t wait to get my hands on a P51 or Spitfire!

Time out! This is where most beginners learn the hard way that a basic trainer is not a warbird trainer.

Flying a plane is an exercise in controlling a moving object in the air – speed is something to consider very carefully when selecting any model. A trainer flying at a modest 20 mph does not seem too fast, but let’s consider how fast 20 mph is in feet / second:

Let’s say your 30 feet off the deck and have to correct from a bad turn – you have one second to do it. Presumably you’ve honed your reaction time so that you can recover OK. How much time does a warbird give you? Let’s say it’s cruising speed is 40 mph:

If you’re 30 feet off the deck, you now have a half second to recover – and this for a new plane with unfamiliar, and unforgiving, handling. In level flight on a small field, blink your eyes and it’s gone. If you like to glue small foam pieces, this is a great way to do it.

Let’s start from scratch – what should you look for?

1. Ailerons: If you’ve learned with rudder and elevator, the next step is ailerons. Most likely you’ve learned using the right stick for rudder and elevator control, so graduating to using the right stick for elevator and ailerons is not a jarring change. Banking right or left will be more responsive but not all that different. The rudder is now on the left side with the throttle – unless your plane has a steerable tail wheel, you can easily fly without touching the rudder.
2. Fly Fast or Slow: You’re still learning – flying an unfamiliar plane that requires a fair amount of speed to stay airborne cuts down on your reaction time – a plane that is flyable fast or slow mitigates this problem.
3. Moderate Wing Loading: The higher the wing loading, the faster the plane must fly to stay aloft; ideally something under 15 ounces/ft² will keep things reasonable.
4. Dual Rates: The transmitter should be capable of setting the control surfaces for two rates – low and high
   rates. This means that with a flick of a switch, the control surfaces will move just enough to control the plane moderately (Low Rates); after gaining experience with the plane, you can select High Rates for more aerobatic-like rates.
5. Highly Survivable: You’re still learning – you need a plane that will not turn into a pile of foam or toothpicks the first time you have a “close encounter of the ground kind”. This means foam of some kind.
6. Easily Repairable: This does not mean only that spare parts are available – the plane should be “glue friendly” so you can easily make those inevitable small repairs that crop up.

If you have an RTF, the first decision you have to make is “Do I go RTF again, or do I buy a re-usable transmitter package?”

Most likely the RTF package you have is a three channel rig – ailerons with rudder require a minimum of four channels, so porting your three channel RTF rig is not feasible. This article lists some radios to consider – definitely go for the best computer radio you can afford.

If you decide to buy another RTF package, your choices narrow fairly quickly – IMHO there are two good RTF options available which meet most of the criteria listed above. Many of the other “intermediate” RTF planes use ailerons but no rudder – so you’re buying another three channel rig.

• Wingspan: 23.5 inches
• Wing area: 340 in²
• Flying Weight: 6 1/2 oz
• Wing Loading: 2.8 oz/sq ft

My favorite plane – my full review HERE. The Bug can be set up as a trainer or for full aerobatics – it can be bought as an RTF with a Spektrum DX6 radio – this is one of the top six channel transmitters on the market and will serve your needs for years to come. I can attest from my own experience that the Bug is extremely tough and a great park flyer – a forum on it HERE.

• Wingspan: 39.8″
• Flying Weight: 20.5 oz
• Wing Loading: 8.4 oz/sq ft

This is made of easily repairable foam and is very tough. The multiplex is available as a kit, ARF or RTF package. Do a search on the RC forums and you will see many positive references on it.

• Wingspan: 37.8″
• Wing Area: 265 in²
• Flying Weight: 16.9oz
• Wing Loading: 9 oz/sq ft

The GWS Estarter is one that many recommend as an aileron trainer. This is an ARF but it’s a good start. Do a search on the RC forums and you will see many positive references on it.

It’s very easy to succumb to the dark side – resist the temptation to jump from that docile high wing trainer to a snarling war bird as your second plane. Some do and they’re fine – most transitioning from a basic trainer will not have a great experience. A better plan is to graduate to a tough, repairable aileron trainer with a radio package that’s going to meet your future flying needs.

If you want to build foam, I would suggest the Magpie; if you want to build wood, get the SmoothE with the slow-fly wing – wood fuselage with a foam wing. I just finished one of these. Mountain models can provide the servos, ESC and the motor as well as the battery. They make it very easy for you.

For the Magpie, this would be your lowest cost radio option. Tell them you have this package and they will know what to add.
For a "free" Hitec Radio, go HERE.

For the SmoothE, you will want a little more flexible radio – Hitec Laser – tell them if you get this package and they will know what to add. If you have more budget, then read "Don't Buy a Standard Radio".
Hitec Laser 4 4-Channel FM Micro/2 HS55 Servos

However, if you want to get in to flying in the quickest, least expensive way, I would recommend one of these as your first plane:

I have flown the Easy Star – Great plane for new flyers! It's made of super tough foam, a good parkflyer and a good glider.
In the US the RTF package comes with a 72 MHz radio system that can be used to fly other planes

• Build Thread
  HERE and
  HERE.
• Videos
  HERE and
  HERE.
• Mods, upgrades and more
  HERE.
• Add Ailerons – Start at post 195
  HERE.
• Travel Box
  HERE.

This is the only semi-scale plane on my list. I have not
flown this one but the flood of excellent reports leads me
to recommend it to new flyers. If you REALLY need a plane that looks
like something people would be in, this is the one I will
recommend. It takes the same Xport accessories as other
HobbyZone and ParkZone planes so you can drop bombs, parachutes and attach
other accessories to extend your fun. It has a steerable tail
wheel so you can effectively taxi the plane. Great for ROG launches.

• Photos and Videos HERE. Other Excellent Video – Hi res for high speed connect users
  HERE and
  HERE.
• Super Cub Manual
• Discussions on the Forums
  HERE.
  HERE,
  HERE, and
  HERE.

This company is really putting together some outstanding
packages. I have flown the T-Hawk – an excellent first plane.
Get the Extreme value package – it comes with an extra wing,
tail and battery. This plane stands up to hard landings and
can be flown on 27 MHz or 72 MHz.

• T-Hawk – Without Radio – add your radio and receiver
• 
  T-Hawk RTF 72MHz Partner Training Package – $279 -This is really unique!
• T-Hawk Discussion Thread
• Videos

I started on an Aerobird RTF and have hundreds of flights on my Aerobirds. I also thermal and slope soar this plane -
flies well and stands up to hard landings. Their add-on fun accessories for
night flying, air to air combat and drop module add to the fun! The combat module makes a
great lost plane locator, even if you don't plan to fly combat. Great keep-in-the-car
plane – take off the wing and it goes back
in the box fully assembled. Most can't do that!

This thread can be seen HERE.

Hitec/Futaba Channel Assignments
JR, Airtronics and others may use different sequence – doesn't matter

• Aileron in 1 – If you have two servos, you use a Y cable
• Elevator in 2
• Throttle in 3
• Rudder in 4
• Landing gear in 5
• Flaps in 6 – If you have two servos, you use a Y cable

I usually power up the radio and select a new memory position. If I am
replacing an existing profile that I am no longer using, I reset all values
to stock settings of 0 or 100% as called for in each case.

This procedure assumes you have your servos mounted and the control
rods/cables attached to the surfaces and the servo arms off the servos.

Power up the plane. If this is an electric plane, I use a 4 cell receiver
pack battery rather than the motor battery attached to the BEC in the ESC as
I don't want the motor in play right now.

Check for servo direction. When you work the servo, will the servo move the
surfaces in the proper direction? If not, you use the servo reverse feature
to change their direction. If you are using a standard radio that doesn't
have servo reverse, then you need to remount the servo so the arms move in
the right direction.

To center the surfaces, I hold the surfaces centered with one hand and put
on the servo arms, connected to the rods or cables, so that I have the
surfaces centered as close as possible when I set the arms on. If I have a
screw on/off clevis at the servo end, I will make adjustments so that I can
put the servo arm on and be sitting right at the point where the surface is
centered.

When happy with the position, I set the servo arm and put in the servo arm screw.
If necessary I might add some adjustment at the surface end if it has an
adjustable clevis to further center the surfaces. This is especially
important if you don't have the ailerons or the flaps each on its own
channel. I want them 99% right from the mechanicals.

Only when this is done do I do any final centering using the radio. On my
radios, the menu is subtrim that is used to center the servos AFTER you have
done as much mechanical centering as you can. If each aileron or flap is on
their own channel, then I can do more from the radio for the
final fine tuning.

You can adjust max throws using control horn position but I normally do this
from the radio. I use the radio's ATV/EPA to set the max throws on each
channel.

Then I would decide on what I want for dual rates and exponential on each
channel. Typically I use 100% high with 30% expo and 70% low with 30% expo
as my starting points.

Now, if you don't have flaps and you have your ailerons on separate
channels – 1 & 6 in this example – then you may want to set the flapperon mix
so you can adjust them individually from the radio and set aileron
differential if you like. This also allows you to retask the ailerons as
flapperons for landing.

If you don't have retractable landing gear, some radios will let you put the
second aileron on channel 5, or the second flap servo on channel 5.

If this is a glow plane, then you use the same procedure to adjust the servo
that will control the throttle. If this is an electric plane, you should
follow the procedure recommended by the ESC maker.

That would be basic set-up.

• Once you get to the field, be sure to a range check before you even think
  about flying
• Make sure you have the right model selected on your computer radio
• Confirm all surfaces are moving in the right direction
• Confirm there is no binding of any of the control rods, cables or the
  surfaces
• Confirm everything is centered

When you do your first flight, ASSUME THERE IS A MISTAKE or that the plane is
out of trim because you are going to have to be prepared to deal with a
problem very quickly.

Once you get it into the air and flying at a good height, then you start to
check the trim and make whatever changes are needed. Remember that a
handling problem may be do to an incorrectly set CG. This might be masked by
adjustments you can make in trim, but that will make the plane fly
inefficiently and may even make it dangerous. So be sure your CG is right as
well.

This thread can be seen HERE.

The first step is to determine your power requirements. Since the objective is to drive a plane, you have to determine what your plane needs to fly the way you want. For example, is the plane a trainer, scale model, aerobatic or full 3D? Each will need a different power plant. One criteria to determine motor sizing is based on watts/pound (total flying weight):

• 50-70 watts/pound: Minimum level of power for decent performance, good for lightly loaded slow flyer and park flyer models
• 70-90 watts/pound; Trainer and slow flying scale models
• 90-110 watts/pound: Sport aerobatic and fast flying scale models
• 110-130 watts/pound: Advanced aerobatic and high-speed models
• 130-150 watts/pound: Lightly loaded 3D models and ducted fans
• 150-200+ watts/pound: Unlimited performance 3D models

Another method is to determine the required thrust/weight ratio. For this you start with the total flying weight of the plane:

• 50% thrust to weight ratio: Minimum required for "sedate" flying
• 80-100% thrust to weight ratio: Recommended for trainer type planes – enough power to get out of trouble easily
• 120% thrust to weight ratio: For unlimited vertical performance and 3D flying
• 200-300% thrust to weight ratio: For speed and wild aerobatics with light weight foam planes

Almost all motors sold will spec their power requirements such as seen below:

In this instance, you can estimate total watts by multiplying the volts by amps – in this case 12 volts x 22 amps (continuous) = 264 watts.

Note that there is no thrust data – not all will give thrust data. Scorpion is one that does gives excellent data on each motor:

Note that the propeller used will have a large impact on power requirements. For more on Propeller Selection, go HERE.

In general, slow flying props are designed to deliver high thrust at relatively low rpms and "E" props are designed to enhance speed over thrust. For example, if you have a scale biplane, a slow fly prop might be more appropriate; a war bird, eg a P51 Mustang, typically flies faster and will use an "E" prop.

Once the motor is selected, you need to match a battery to the motor's power specs. Let's assume your motor/prop combination will draw 15 amps. The lipo battery that will meet this requirement must be capable of delivering at least 15 amps on a continuous basis. This is where the battery's "C" rating comes in.

Lipos are rated by voltage and capacity; capacity is stated in mah – milli amp hours – a measure of how much the battery holds. As an example, if you look on this label you'll see six key numbers (circled in red):

The "25C cont" means 25C continuous; the "40C burst" refers to how fast the Lipo can be rapidly discharged for a SHORT time period, something like 15-30 seconds; look at this as the "supercharger" rating – to be used rarely. The second set of numbers – 55A cont/88 burst – are what this battery can deliver to the system considering its capacity – 2200 mah.

The two ratings – mah and "C", combine to tell you how intensively this battery can be used with the following formula:

In our example the battery at a minimum MUST deliver 15 Amps. If you over-discharge a lipo battery, it will get VERY hot and probably catch fire; at a minimum it will ruin the battery. To be safe, it's a good practice to use a battery that will deliver MORE THAN what's required – the motor will draw only what it needs, you can not "force feed" it with a larger battery.

Once you've matched your model's power requirements to a motor/prop/battery combination, you need an ESC that will handle the power required. ESCs are rated in Amps, so you need an ESC that will handle the maximum required Amps. In our example of a motor drawing 15 Amps, you need a 15 Amp brushless ESC. These ratings are typically written on the ESC:

This one is rated at 35 Amps at a maximum of 15 volts. It's a good practice to use an ESC that's rated for at least 30% more Amps than you need – it will run cooler and you will not stress it as much as one rated closer to your requirement. In our example where the motor will draw 15 Amps, an ESC rated for 20 amps will give you a nice safety margin.

A little homework up front will go a long way to keeping your flying trouble free. If your motor does not have any data, you need a wattmeter to help in your setup. A rule of thumb that can get you started is that in general a motor will deliver 100 watts/ounce of motor weight. However, it's only a rule of thumb and only real world testing will give confirm a trouble free setup.

The prop's job is to accelerate air to keep the plane flying – the result is measured by thrust. We can estimate thrust for a given prop at a given rpm by the following formula:

You can see the large impact a prop's diameter has as its impact on the volume of air is squared. The power needed to turn a prop depends on its rpm, diameter and pitch as shown in the following equation:

A propeller's pitch is the theoretical distance it will travel along the axis of rotation in one complete revolution – the more pitch, the more the prop will travel, and consequently the faster the plane will travel – ie more speed. As the equation shows, a prop's diameter once again has more impact on required power than its rpm – replacing an 8 inch prop with a 9 inch will have a large impact on required power.

A simple formula to estimate a prop's load factor (PLF – credit to Lucien Miller for this) is:

Using this formula can help in determining equivalent props as shown below:

This can also give a good approximation on how the power requirement will change when switching to a different prop. It is certainly possible to trade off diameter and pitch to keep the power requirements about the same among various prop sizes.

There are basically two prop types in popular use:

• Slow Fly: Props designed to deliver high thrust at relatively low rpms (hence lower air speed) are designated as Slow Fly props. These props have a larger blade area compared to "E" props to move more air at lower rpms and the pitch will be finer – 10×4.7 is one example. Slow Fly props are more delicate than "E" props – although not all manufacturers give rpm limits, generally limiting these props to 65,000 rpm/diameter is a good practice – eg a 10" slow fly prop should not exceed 6,500 rpm.

  A slow fly prop is like a car's low gear – lots of power to start, climb hills etc, but driving on the highway at 70 mph in second gear is NOT recommended. Consequently slow fly props enable fast takeoffs, quick climbs, vertical acceleration, hovering and 3D type maneuvers better than "E" type props, but at the expense of a lower top speed. Overall high-drag planes, such as biplanes, are more suited to slow fly props.

   

• "E" Props: These props designed to enhance speed over thrust and have more pitch and lower diameter – a 9×7 is one example. These props look more "traditional" than slow fly props and will be faster in level flight than a slow fly prop – this if fifth gear, the "highway" gear for speed on level surfaces. E props are designed to handle higher rpms than slow fly props – although not all manufacturers give rpm limits, generally limiting these props to 190,000 rpm/diameter is a good practice – eg a 10" E prop should not exceed 19,000 rpm. Overall low-drag planes, such as flying wings, pylon racers etc, are more suited to E props.
  Props and Motors

  The prop used with the motor determines its load in amps – the volts are determined by the battery. Almost all motors specify some range of props to use with them – some more than others. E-flite, for example, typically recommends props this way:

   

  

  Not much to go on. Scorpion gives you a wealth of data:

   

  

  The Scorpion data is based on actual bench test data and enables you to fine-tune your setup. Other motor manufacturers supply varying levels of prop data; if you buy or have a motor that does not supply this data, then you must develop your own using a wattmeter to determine acceptable motor loads. Lacking any data on a motor places a real burden on the user – a start is to do a search for similar looking/size motors and use these specs as a starting point.

  Bottom Line: If you have a motor and can't find any specs, you need tools to make them up, a wattmeter at a minimum. A rule of thumb you can use is that each ounce of a brushless motor can handle about 100 watts of power; considering that you can't find any specs, this is likely a low-end motor and something like 80 watts may be more appropriate.

  There are modeling tools, such as MotoCalc, which can generate recommended propellers for a given configuration, but if you have no data for the motor you're using, this tool is not going to help much. In fact, any tool is a "GIGO" process – garbage in, garbage out; you need accurate data to approximate a real world result.

Pitch – this changes the angle of attack, AOA, of the wing. You
can think of pitch as up and down but it is really an AOA control. By
changing the AOA we change the lift characteristic of the wing.

Roll – This control rotates the wings about the axis of the fuselage. We also call this "banking" the plane. Roll is the primary method used for turning your plane.
By redirecting the lift of the wings in the direction you want to
turn,the lift force will take the plane in that direction. We often add
"up"once we have rolled which increases the angle ofattack of the wings
to increase the lift generated by the wing in the direction we want to
go. As "up" is normally into the turn when we are rolled, up will
increase the rate of the turn. This is some times called bank and pull
or bank and crank turning.

Yaw – the rotation of the plane around a point near the Center
of Gravity of the plane, as if it were hanging from a string at that
point. This would move the tail/nose left and right along a flat
plane.Yaw alone will cause a flat winged plane to skid along in the
direction it was traveling until the drag of the fin and fuselage push
it over . This is not a primary turning method.

Yaw control is useful for "crabbing" into the wind on landing approach
or keeping the nose up in a knife edge, as well as other things.

Dihedral or polyhedral – This is the up sweep of the wing seen
in some planes. In rudder only planes, this is necessary so that the
rudder, in combination with the wing's dihedral, can bank the plane. As we
yaw the plane using the rudder, we present one uplifted wing tip to
the oncoming air stream, which increases the lift on that tip while
decreasing the lift on the opposite wing.

This causes the wings to roll
which will result in a turn. Again we can increase the AOA – add "up" -
to increase the rate of turn. When we remove the yaw force by straightening
the rudder, the dihedral in the wings will tend to return the plane
to level flight. That is why beginner planes, whether they have ailerons
or not, tend to have significant dihedral in the wings, it makes them
more self correcting.

Many planes with ailerons also have dihedral in the wings but here it is
primarily for stability, as the ailerons will be used most of the time
to roll the plane.

Pitch is controlled by motor speed, elevator, canard, elevons, or a combination depending on the design of the plane.

Roll, your primary turning control, is handled by the
ailerons, wingerons, elevons or, in planes without ailerons, roll is
produced by combination of rudder and wing dihedral. Roll is always your primary turning control.

On planes that have ailerons and a rudder, yaw is a secondary
turning assist to provide smoother turns and more efficient turns in
combination with the ailerons.

Yaw control, via the rudder, is very important in many acrobatic
moves.The yaw control is also your primary directional control on the
ground. This is done with the rudder or a combination of rudder and
a turnable ground wheel. In many cases the ground wheel is attached to
the rudder itself.

So, pitch, roll and yaw are your control axis. They can be controlled
by a variety of methods depending on the design of the aircraft.
Certainly helicopters also have these control axis but they use
different methods than fixed wing aircraft.

If we add the speed control, we can relate this to the control sticks using Mode 2 layout, which is the standard in North America.

In Mode 2 we have pitch and roll on the right stick and speed and yaw
on the left stick. What surfaces and devices those sticks control
depends on the design of the aircraft. For example, sometimes rudder is
on the right stick and sometimes it is on the left. Sometimes throttle
is on the left stick as our speed control and sometimes, as in the case
of gliders, we tend to put the flaps on the left stick as our speed
control.

If you think in terms of pitch, roll, yaw and speed, your controls
always make sense regardless of what type of aircraft you are flying.

This thread can be seen HERE.

I always suggest that new flyers start in very calm conditions regardless of
what plane they get. This way they can focus on the plane and not fighting
the wind. If you can do this and be strong about avoiding anything above
about 3 mph, then you can train close to home.

Once you have 10-15 solid flights in a row with safe landings, then you can
move up the wind scale a little at a time as you gain confidence. This
could be accomplished in a few 2 hour sessions. Or it could be done in a
single 4-6 hour day if you have 3-4 batteries and have a charger or two you
can use at the field. Of course, this assumes you don't smack up the plane.

Some of these will tolerate 5 mph and some up to about 8:

Best flown in still to under 5 mph breeze. This is good for people who want an
RTF and only have a small space to fly or who have an indoor place to
fly, such as a gym or similar space. The Slo-V can take the X-port combat
module and the bomb/parachute – tons of fun in a small space.

T-IFO Review
Complete package with radio – $275
T-IFO Combination Deals

Can also be flown indoors in a gym or similar space.
Slow stick Complete Package including radio – $150 (need battery charger)
Slo-Stick Information
Discussion Thread
GWS Slow Stick ARF Park Flyer
Slo-Stick Video
Souped up Slow sticks go vertical

Backyard Flier Review

If you have the money I would recommend a computer radio such as the Spektrum
DX6 or the Futaba 6EXAS as entry level computer radios.

GWS 12V Peak Charger MC2002 – $42

Can charger from a car cigarette lighter – there are cheaper chargers, but this one looks good for this plane and
future

I have a very specific position on radios – Don't buy a Standard Radio!!!

Computer radios are now so inexpensive and offer so much more than standard
radios that it doesn't make sense to get anything but a computer radio. Don't
get me wrong – there are many good standard radios but for only a few bucks
more you get a much more capable computer radio that can do more for you than
any standard radio and can save you money by time when you get the second plane.
They can also make it easier to fly your plane, perform aerobatics and more.

Below are five radios – all will fly your typical parkflyer. All but the DX6
can also be purchased with larger servos suitable for larger planes and
gliders. Two are standard radios for the uncommitted or low budget first
time flyer. These will get your plane off the ground with very basic radio
features for a low price. Each package I list include radio, micro servos,
micro receiver.

Hitec Neon 3 – 3 channel standard radio $59
2 micro servos, micro receiver, switch, etc
HERE.
For $19 you can add a trainer port to this
HERE.

This package is such good value for that first 3 channel ARF or kit, if you
can't afford a computer radio. ( more on that later ) If you bought the two
servos and the receiver by themselves, that would come to about $60. So
this is about as cheap as you can get into a hobby grade radio that will fly a
three channel R/E/T or A/E/T parkflyer or 3 channel
glider ARF or kit plane. It also does not include rechargeable batteries
which the others do. You run this one on standard AA batteries.

It includes mixing for flying wings or V-tail 3 channel planes as well as
servo reversing. It does not have ATV/EPA or dual rates, however these can
be added later at extra cost. . You can also add a trainer port for
use with an instructor or to connect to a flight simulator. You can add a
4th channel but it is limited so don't think of this as a 4 channel radio. It
can't fly a 4 channel plane.

Hitec Laser 4 – 4 Channel Standard Radio $100
HERE.
My minimum recommended 4 channel standard radio for A/E/R/Throttle
parkflyer,
glow plane or 4 channel glider. Radio, micro receiver, 2 micro servos,
Switch harness, etc. It will fly a 4 channel aileron plane. Includes V-tail
and Elevon mixing, servo reversing, ATV on ch 1&2 . Also has a trainer port
that can be used with fight simulators or a buddy box.

While the Laser is a good radio, pick the Laser 4 only if you are unsure you
will continue in the hobby and want to spend as little as possible to get a 4
channel plane into the air. Not my recommendation for a committed flyer
who plans to continue in the hobby.

In short, computer radios give you things like model memories, exponential,
a variety of surface mixes and more – features not found on standard radios.
Your computer radio can store the profile for many planes and reset itself
for each plane by just selecting the model. Standard radios don't have model
memories or a lot of the other features that computer radios offer.

With a
computer radio, you only need one radio to fly a bunch of planes rather
than dedicating a radio to each plane or resetting the radio each time you
change planes. Computer radios are great! In the end, they are cheaper, more
convenient AND can make it easier for a new flyer to learn to fly.

These are all 6 channel radios so they will let you fly more advanced planes
then either of the standard radios above:

Spektrum DX 6 – $199 – For the committed Parkflyer pilot

Review

If your plans are to fly small to medium sized electrics, often called
parkflyers, hand launched gliders with wing spans under 60 inches, then this
might
be your best choice. The DX6 is suitable for flying within 2,000 feet
out, about 5-7 football fields away. This is more than enough for
these planes and further than most people will fly them.

It has a nice mix of features, 10 model memories and is backed by Horizon
Hobby, so you can be confident of good service. You will never worry about
channel conflict again. This promises to be the RC technology of the
future. Key features: Digital DSMT Spread Spectrum Modulation,
10 model memories, dual rates, exponential, 6 channels, 8 standard mixes and
three programmable mixes. No crystals needed and no channel conflict
control needed.

DX6 Flight experience thread
More information on DX6 from Spektrum
AMA on 2.4 GHz SS

(Note: Micro receiver, 3 micro servos, switch – the
receiver in this package is not appropriate for sailplanes or glow planes, but is
OK for parkflyers/low speed electrics)

The Futaba 6EXAS is an entry level computer radio for the committed flyer
who
also plans to fly glow planes, thermal duration gliders or electrics over
60" wing
span. Six channels, 6 model memories, a good mix of features and
convenience
that will carry you a long way. The link is to a package that is good for
parkflyers, but there are other packages if you need larger/stronger
components for larger planes. For about $30 more than the Laser 4 radio, you
are miles ahead in capability!

This particular package
is very attractive for small electrics – comes with
two
small servos AND a 20 amp ESC, 6 channels, 4 model memories, a good mix of
features to carry you forward. The VG 6000 is also available with larger
components so it can also fly glow planes and TD gliders that need greater
range than the DX6 offers.

There are lots of other good choices in computer radios that have more
channels, more features and a higher price; however, these would be
excellent
choices for the first time radio buyer or someone stepping up from RTFs who
knows they will continue in the hobby.

Note: This article is a reprint by author's permission.

• Battery Basics
• Notes on Lithium Batteries
• Safety Warning on Lithium Batteries

These are typically made
from NICD or NIMH cells that are designed for lighter loads than motor
batteries. As such, they need also to be charged at slower rates. The
general rule is 1/10 C charge rate where C is the rated capacity of the
battery. So, on a 600 mah transmitter or receiver pack would be charged at 60
mah.

At this rate you would charge an empty pack for 10 hours to bring it
fully up to charge and in fact you have to charge them a little longer than
that to really get them fully charged, so figure 12 hours to be sure. This is
handled nicely by the charger that comes with the radio system. This is an
example of such a charger
HERE.

Quick charging these packs is not recommended as a standard practice.
If you quick charge them, they will likely get hot. Don't quick charge them
in the plane or the radio as the heat build up could damage some of the
surrounding electronics or might deform plastic or epoxy based components near
them. Fast charging at 1C will generate a lot of heat and can lead to early
pack failure which could happen during a flight.

There are after market chargers that are focused on transmitter and receiver
packs. Here is an example from AccuCycle
HERE.

Charge 'em slow and treat them right and they should last for years. If you
tend to fly for long periods, pick up an extra transmitter and/or receiver
pack and charge them slowly, at home. Here are a couple of examples.
HERE and
HERE.

The motor on the typical parkflyer needs to pull power at a much higher rate
than a receiver pack can provide. So the batteries that power the motors are
typically of a different design/grade so that they can supply electricity
at these rates. As a result when we charge them we can charge them much
faster too.

The general rule here is that NICD motor packs can be charged in the 1.5 – 3C
range with 2C typical. NIMH packs are best charged at 1- 2C with 1.5C
typical. Higher performance packs can take the higher rates. See what the
maker recommends. This way you can get in your flight, then put the battery
on a charger and be ready to fly that pack again in 15 minutes to an hour.
Have 3-4 packs and 2 field chargers and you may never have to stay on the
ground for more than a few minutes. That's the way I do it.

Lithium motor batteries are becoming popular. However their chemistry is very
different from NICD and NIMH cells. As a result they need a different type of
charging process. If you are using Lithium packs, you MUST use a charger that
is specifically designed to charge lithium or you could end up with an
explosion and/or a fire. This is not joke. Don't ever put a lithium pack on
a charger that is not designed for lithium cells. Follow the charge rate
recommendation of the battery maker carefully!

When we talk about battery packs, a designation of XSYP is sometimes used.
This indicates how may cells are in serial and how many groups of these cells
are connected in parallel. While the terms are most common in the Lithium
world, they can just as easily be applied to NIMH or NICD packs.

Fro exampld, a 3S2P pack is made up of 6 cells. There are two groups of 3 cells. The
three cells are connected in series. This is the 3S designation. When
connected in series their voltages add. So 3.7V Lithium cells in a 3S
configuration would have a voltage of 11.1V and be designated as a 3S1P pack.
If these cells were rated at 2000 mah each then this would be a 3S1P 11.1V
2000 mah pack.

Now if we took two of these 3S1P packs and connected them in parallel, the
capacity adds, not the voltage. So this would now be a 3S2P pack rated at
11.1V and having a capacity of 4000 mah. Like connecting two gas tanks
together. The motor in you truck would not be stronger but you could drive
further because you are carrying more fuel.

You could do the same with NICD or NIMH packs.

There are timed chargers and peak chargers. Timed chargers, often bundled
with RTF airplanes, work well if you always run your pack all the way down. If
you have one, use it, but I don't recommend you go out and buy one. Peak
chargers, are the way to go – they read the pack and know when it is fully
charged.

An AC powered charger is convenient to use at home but won't help you
recharge at the field. All of mine are DC peak chargers except for my radio
chargers. I have a car booster pack that runs my DC equipment in my shop.
And by the way – I have used it to jump start cars. Works great!

While many peak chargers are focused on charging motor packs, most also have
low charge rate settings that can be used to charge transmitter/receiver packs
too. Here are a few examples of peak chargers for your consideration. I have the
first three shown here.

HobbyZone Peak Charger – $19

Simple and inexpensive – I have 2 of these from my Aerobirds. I added
different types of connectors so I can use them for all kinds of battery
packs. They work just fine. 4-7 cells NIMH and NICD

Hitec CG-340 – $39

I have had this one for 24 months. This is an older
model; it works well but there are better choices out there. You need to make
or buy leads Easy to use for NIMH and NICD – up to 16 cells.

Triton Charger – $130

This one showed up under the Christmas Tree – .
Better than the CG-340 – it handles up to 24 cells NICD/NIMH cells or 4 cell
Lithium cell packs as well as Lead/acid field box batteries.
It will also cycle battery packs which my others will not do. So far I am
very happy with it.

Triton Reviews:

rcbatteryclinic.com
radiocontrolzone.com

I don't have these but have heard good things about them:

GWS MC 2002 Peak Charger – $49

Seems to be a good value for a first charger for NIMH and NICD packs of 4-12
cells. It has charge meter, but not the digital display or memories of the
Triton or others. Includes a variety of connectors. It can not slow charge
receiver/transmitter packs due to 90 minute charge time cutoff.

towerhobbies.com
horizonhobby.com
gws.com

Great Planes PolyCharge4 DC Only 4 Output LiPo Charger – $100

If you are seriously into LiPoly (not Li-ION), this may be the charger of your
dreams. Charges 4 Lipoly packs at one time. Each charge port is limited to
30 watts, so it can charge 1S or 2S packs at up to a 3 amp rate. 3S packs can
be charged at up to about 2.5 amps and 4S packs can be charged at about 2 amp
rate.

Therefore, this charger seems a very good choice for 1S or 2S packs up
to 3000 mah capacity, 3S packs up to about 2500 mah and 4S packs of up to
about 2000 mah. You can charge packs of higher capacity but it will take more
than 1 hour to charge based on the typical 1C charge rate for LiPoly packs.

If you have packs with a 2, 3 or 4P designation, this charger might also be
good for you. 3S4P packs up to about 10,000 mah would work well if each 3S
component can be charged separately. 4S4P packs up to about 8000 mah would
also work, if you can charge them as four 4S1P packs of 2000 mah each.
Discussion thread on this charger
HERE.

A review of a group of Lithium battery chargers
HERE.

Sometimes I have 3 chargers running at the field at one time charging motor
batteries for my parkflyers or receiver batteries for my sailplanes. I hate
being grounded. So they are put to good use.

Note: This article is a reprint by author's permission.

This excerpt from Thunder Power's Lipo Safety Warnings pretty much says it all – Lipos are a great power source with high density storage – but they do require careful handling. Now if you think this is a bit of an over-reaction, look at this picture:

There were a number of laptops and cell-phones that were catching on fire – guess what kind of batteries were involved?

When a lipo is shipped from the factory, the cells are most likely "balanced" – that means if you measured each cell's voltage, they would be substantially the same – let's say 4.0 volts.

There is no such thing as 2, 3, 4 or more perfectly balanced cells for the life of the battery. Gradually one or more cells can vary in voltage from the others and as the difference increases, the probability of damage increases. If the lipo charger you have does not have a built-in balancer, then each cell will get the same charge. If one cell is higher than the others, this cell will be overcharged, and THAT'S the problem.

When you CHARGE a lipo, it's done at 1 "C" – this means that you have to set the charger to deliver only as many amps into the battery as its rated; eg, a 2200 mah lipo is 2.2 Amps (all you're doing is moving the decimal 3 places to the left – milli = 1/1000), so you can charge this lipo at a rate of 2.2 amps. If you're not in a hurry, then charge it at less than 1C – just takes longer.

Lipos take a charge to 4.2 volts – NO MORE! Overcharging a Lipo can result in a fire with acrid smoke – no fun in the house. So charging a Lipo with anything BUT a charger designed for it is playing with fire – literally. Charging it at a higher rate will damage the lipo and it can result in a fire.

To avoid this problem and increase your lipo's life (lipos can take as much as 500 charging cycles; unbalanced lipos last much less), equalizing the voltage among the cells – balancing – is required. If you have a charger that incorporates a balancer, then you're fine; if not, you need a separate Lipo Balancer.

A Lipo Balancer (I reviewed the Thunder Power's Cell Balancer #TP-205v HERE.) does exactly what it says – it balances the cells by discharging a higher voltage cell to the lowest cell level – hence the term "Balancer" – all cells are of equal voltage.

Using one is drop-dead simple – lipos now come with a separate balance plug. Plug it into the balancer and it will start to do its thing – it may take 10 minutes or maybe an hour depending on how out of balance the lipo is; if it's in balance, it will tell you – the Thunder Power uses a system of colored LEDs.

However, as of yet there is no standard lipo balance plug, so you may have a Thunder Power Balancer and a lipo with a different balance plug – that's why God made adapters; this is something you'll have to live with.

A damaged lipo is not shy – you will know VERY QUICKLY if a lipo is damaged:

• If one or more cells is "puffed" – ie acting like a balloon – it's toast; discard it.
• If you crash and the lipo is punctured, odds are that it's toast. Remove it from the plane, place it in a fire-safe location and watch it for about an hour. If it's still hot or it's puffing, it's toast.
• If you charge a lipo and it only takes 80% of its charge, it's toast.
• If you charge a lipo and it gets hot – it's toast.

Check with your lhs or local waste disposal facility for proper disposal.

A lipo is NOT a ticking time bomb. However, it DOES require some care in its use. Proper charging and balancing are two pre-requisites for trouble free flying.

Scorpion motors are made on the most modern CNC equipment available, so from a purely mechanical standpoint, they are manufactured as well as a Hacker or AXI motor. The fit and finish is second to none, and there a few nice touches like the laser engraved part number and company logo, and the angle cut cooling holes on the front housing that act as an air pump while the motor is running to pull cooling air across the stator and motor windings.

The biggest difference in Scorpion Motors is the magnets that are used in the construction of the motor. Before I go into the details, I think it would be best to give a little bit of background information about the magnets used in brushless motors in general, so you will understand how important this is. This will take a little bit of time, but once you get to the end, you should have a very complete understanding of how a motor works and how power, heat and magnets interact with one another.

The magnets used in our brushless motors are a ceramic material that is comprised of Neodymium, Iron and Boron, and are often referred to by their chemical symbols from the periodic table as NdFeB magnets. Since Boron is a fairly toxic substance, the magnets are chrome plated after manufacture to seal them up. This serves three purposes:

1. Protect the users from Boron exposure;
2. Seal the magnets so they do not absorb moisture, which can cause the magnets to break down over time;
3. Strengthen the magnets, since the ceramic material is fairly brittle.

The magnets have two major properties, their magnetic strength, usually expressed in the units of MegaGauss-Oerteds, and the temperature rating, which is expressed as a letter suffix to the strength value. The strength value of NdFeB magnets varies from a low of around 28 MGO to a high of 50 MGO. The majority of high-end name-brand brushless motor use magnets in the 45-50 MGO range.

The one downside to NdFeB magnets is that when compared to other types of magnets, such as Samarium Cobalt, they have a relatively low operating temperature. The majority of magnets used in motor construction have a maximum operating temperature of 100ºC or 212ºF. Operation above this value will cause a permanent and irreversible loss of magnetic strength in the magnet. The amount of magnetism lost increases as the temperature increases, and once you reach the Curie temperature of the material (around 310ºC), all magnetism is lost.

NdFeB magnets are available in several different compositions with varying maximum temperature ranges. These temperature ranges are signified by a letter code after the strength value. Here is a list of the ones that are currently available, along with the max temp:

• 80C – No suffix
  
• 100C – M
  
• 120C – H
  
• 150C – SH
  
• 180C – UH
  
• 200C – EH

The entire part number of a magnet normally starts with a letter "N" to signify that it is a NdFeB magnet, which is then followed by the magnet's strength, and finally its temperature rating. So common magnet part numbers would be N48, N45M, N42H, N35UH N30EH and so on.

Typically, as the magnet's strength goes up, the maximum operating temperature goes down, so you end up with the following commonly available magnet strength-temp ranges:

Now with that understanding about the magnets, I can move on to explaining the magnets used in Scorpion motors. As I stated earlier, most of the better motor manufacturers are using N50 or N48M magnets in their motors. Using an N48M magnet gives you a motor that can withstand 20ºC more temperature and still have 96% of the magnetic strength of an N50 magnet, so it is a good trade-off. For cost reasons, the majority of the cheap Chinese No-name import motors use N35 or N38 magnets in either 80ºC or 100ºC temperature ratings.

Scorpion wanted to build a motor that in normal use was virtually impossible to burn up, so they went to the best magnet manufacturer on the planet and looked at magnet options. After going over all the options, Scorpion discovered that it is possible to create an N50 magnet with an EH rating, that would be good for 200ºC operation.

Currently there are only two magnet manufacturing companies on the planet that have the equipment and the technical know-how to produce such a magnet. To produce these magnets, it takes some extremely rare trace elements to mix in with the Neodymium, Iron and Boron, and in order to make it economically feasible, a LOT of them need to be made in the production run.

Since Scorpion wanted to make the best motor available, they decided to go ahead and have N50EH magnets custom made for them, and they are the ONLY motor manufacturer that has them. Because of this, Scorpion motors are the only motor made that can operate at temperatures exceeding 150ºC and sustain no damage whatsoever.

To complement the incredible magnets used, Scorpion uses wire to wind their stators that has an insulation which is rated for 180ºC. These two components combine to produce a motor that can handle at least 50% more power than any comparable motor without burning up.

Most people will tell you that, "I never burned up my magnets, it was the wire that fried". What they don't understand is the reason the wire fried is because the magnets DID start to de-magnetize. When a motor fails due to the windings burning up, in most cases it is due to the magnets getting too hot. Let me explain:

{mospagebreak}

When a motor is running under power, it not only functions as a motor using up the electricity being sent to it, it also functions as a generator, supplying power back to the source. This is why a motor draws less current when it is running than when it is stopped. Here is an example to explain this:

Let us assume we have a motor that is running on 10 volts, has a Kv of 1000 and has an Rm value (motor resistance) of 0.1 ohms. In an ideal situation, if you put 10 volts on this motor it would spin at 10,000 RPM. We all know that it will spin a little slower than that due to the drag of the bearings, the air on the motor and other factors. Let's say that in this case it spins at 9,800 RPM.

Now since the motor can act as a generator just as well as a motor, a motor with a KV of 1000 will also generate 1 volt for every 1000 RPM that it is spun by an external source, even if that external source is the motor itself.

In the case just described, the motor has 10 volts applied, and since it is spinning at 9,800 RPM, it generates 9.8 volts. When you take the difference between these two voltages, you get 0.2 volts; if you divide that value (0.2) by the Rm of 0.1 ohms, this yields a no-load current (Io) of 2 amps. This is a simplified version of the Io calculation, but it explains the point. Now, as you put a prop on this motor and load it down, the motor turns slower, and as a result it generates less internal voltage.

Let's say that you prop the motor so it now turns 9,000 RPM with 10 volts applied. In this case, the motor will only generate 9 volts. When this is subtracted from the 10 volt supply, you have a difference of 1 volt. Now, if you divide this 1 volt by the Rm of 0.1 ohms again, you will see that the motor will now draw 10 amps of current. If you put on a bigger prop and slow the motor down to 8,000 RPM, it will draw 20 amps of current, and so on.

So know you know why motors draw more current as the prop load increases and the motor RPM decreases, so how does this all pertain to burning up magnets?

The heat that is generated inside the motor is proportional to the square of the current.

Since the formula for power can be expressed as

where P is power, or in our case heat, I is the current flowing through the motor, and R is the resistance of the motor, or Rm in this case. Every motor has a mass of metal inside it, namely the stator, and this makes up a large portion of the total weight of the motor. Since the stator is in direct contact with the wire motor's windings, it takes the brunt of the heat that is generated by the motor windings. In most of our motors, the magnets are only a few thousandths of an inch away from the stator, so as the stator heats, a large portion of this heat is passed on to the magnets, since they are so close.

The amount of heat a motor can take varies with the size of the motor, but a generally accepted rule of thumb is that a motor can safely handle 100 watts of power per ounce of motor weight. Some can take more, and some can take less, but this is a good middle-of-the-road value.

For our example that we have been using so far, let's say that the motor we have been using weighs 3 ounces, so it can safely handle 300 watts of power. With 300 watts of power in at 10 volts, the motor would be drawing 30 amps of current (Watts = Volts x Amps, so Amps = Watts / Volts). In this condition and using the numbers we derived earlier, a motor pulling 30 amps of current will generate 7 volts. Since 7 volts is 3 volts less than the supply voltage of 10 volts, and the Rm value is 0.1 ohms, 3 volts divided by 0.1 ohms is 30 amps of current [((10-7.0) = 3.0)/0.1 = 30 Amps]; since the motor has a Kv of 1000, then it must be turning at 7,000 RPM (1000 x 7 volts) with a 10×6 prop.

I know that this is a lot of numbers, but if you can follow along you can clearly see how Voltage, Kv, RPM and Current all interact in a motor as the prop load changes. Now with all that said, we can finally address the heat issue of the magnets!

With our motor now spinning at 7,000 RPM and drawing 30 amps of current, we are putting in 300 watts of power (30 Amps x 10 Volts). So how much of this power is going to heat? Since power is equal to I x I x R, in this case it would be 30 x 30 x 0.1, which is 90 watts (remember this motor has an Rm value of 0.1 ohms, the 0.1 in the equation). This means that for the 300 watts we are putting in, 90 watts are going up as heat, and the remaining 210 watts are available to spin the prop. This means that the efficiency of the motor in this condition is equal to 210/300 or 70%.

Now that we have established the maximum operating condition for this motor, we can look at how the generated heat can effect the magnets. We have determined that our motor uses 300 watts of power and 90 watts of that is turning into heat. To get an understanding for how much heat 90 watts is, grab hold of a 100 watt light bulb that has been running for a while. Don't actually do it, but I think you get the picture. Light bulbs are only about 10% efficient in converting electricity into light, so a 100 watt bulb makes 10 watts of light and 90 watts of heat. This is how much heat the hunk of metal called your stator has to dissipate while running at full power.

Fortunately for us, our motors spend most of their life strapped to the front of an airplane that is going through the air while the motor is producing this power, so most of the heat blows out and everything stays cool enough to operate. Let us assume that this motor is using N50 magnets, which are rated at 80ºC. And for the sake of this example, let's say that when the motor is running at 300 watts, the stator temperature is 70ºC. At this temperature, the magnets are still happy, since it takes 80ºC before they begin to get damaged.

Since normal room temperature is 25ºC (77ºF), with 300 watts of power going into the motor it is at 70ºC, so the motor is now 45ºC hotter than it was at the beginning of the flight. Since there is 90 watts of heat being dissipated into the stator, this means that for every 2 watts of power the stator has to dissipate, the temperature will go up 1 degree C. With this value, we can calculate the stator temperature for any current draw of the motor.

{mospagebreak}

I know, it has been quite a journey since we started this, but now we can finally see how all this comes together. Let's say that you have been flying your plane with your 10×6 prop for a couple flights, and you land, flip the plane over and break your last 10×6 prop. Bummer! You go to your tool box and discover that you do not have any more 10×6 props, but you do have an 11×6 prop. So you figure "Oh well, close enough", bolt it on and go flying again. Now what you have done is put into motion a chain of events that will lead to the destruction of your motor, so like an episode of CSI, we will go through all the steps that will lead to the demise of your favorite motor.

The amount of drag that a prop puts on a motor is what I like to call the Prop Load Factor. The load factor of a prop is proportional to diameter cubed times the pitch, so the load factor of a 10×6 prop is 10 x 10 x 10 x 6 or 6,000. An 11×6 prop has a load factor of 11 x 11 x 11 x 6 or 7986, which is 33% greater than the load factor of the 10×6 prop. Since the current draw on an electric motor is proportional to the load factor of the prop, we can estimate the current draw based on the load factor:

The 10×6 prop, with its load factor of 6000, pulled 30 amps from the motor. This means that for every 200 units of load factor, the motor will draw 1 amp of current. Using the same ratio, the 11×6 prop, with it's load factor of 7986, will cause the motor to draw 39.93 amps, which is a 33% increase in current (7986/6000 = 1.33, or 33% increase).

Now let's see what this does to the motor: Since the power dissipated in the stator is equal to the current squared times the resistance, or I x I x Rm (I= Amps), the new power dissipated in the stator is equal to 39.93 x 39.93 x 0.1 which is equal to 159.4 watts. So now instead of the motor pulling 300 watts with 90 watts (30 x 30 x 0.1) going to heat, we are now pulling 399.3 watts (10 Volts * 39.93 Amps = 399.3 Watts) of power into the motor with 159.4 watts going up as heat. This leaves 239.9 watts to spin the prop and yields an efficiency of 239.9/399.3 which is 60.1%. So the efficiency of our motor has gone down from 70% to 60% and the internal heat has gone up from 90 watts to over 159 watts.

Earlier we calculated that for this motor, every 2 watts of heat energy in the stator would cause a 1 degree C temperature rise – with 159.4 watts, this means a 79.7ºC temperature rise. Since the day we were flying it was 25ºC, if we add the new temperature rise we see that the stator temp has climbed to 104.7ºC! So now, the simple act of changing from a 10×6 prop to an 11×6 prop has caused your stator temp to rise from a safe value of 70ºC to the now dangerous level of 104.7ºC!

At this point you are probably asking yourself "Why would that hurt the wire? It is most likely rated for at least 120ºC if not 150ºC, surely the wire will not burn up." As I said earlier, the problem is not the wire, although it will die in the end as well, it is the magnets that will start the ball rolling.

So now your magnets are no longer happy campers, since they have a max operating temperature of 80ºC and the stator, only a few thousandths of an inch from the magnets, is at over 104ºC. Now the permanent and irreversible damage is starting to take place. The magnets begin to lose some of their strength because they heat up beyond their operating temperature. This has two detrimental effects:

• First, it raises the Kv of the motor slightly
• Second, it reduces the ability of the motor to function as a generator

If you continue operating the motor in this condition, a run-away thermal condition will take over and the motor will quickly burn up.

What happens is that the weaker magnets can no longer generate as much voltage. From our earlier calculations, we know that if our motor was pulling 39.93 amps, then it was turning just a hair over 6,000 RPM and was generating 6.007 volts. With the weakened magnets, let's assume that it is now only generating 5.5 volts. This means that now the motor will pull 45 amps. This will cause the heat level to go up to over 200 watts, raising the temp of the motor to 125ºC, and then the magnets will demagnetize some more and the motor will only generate 5 volts, and the current will go up to 50 amps.

Now the heat generated will go up to 250 watts and the stator temp will go up to 150ºC. Now the magnets are really hurting and the motor can only generate 4 volts, so the current goes up to 60 amps, the heat generated goes up to 360 watts and the temperature of the stator rises to 205ºC and, Whoops, all the insulation just melted off the wire and the motor windings short out and the big trail of blue smoke starts pouring out of the back of your motor.

Now since your ESC is working into a dead short, it more than likely let out its magic smoke as well, and if the failure mode was a shorted FET, your battery will follow along behind the other two rather quickly!

And that is exactly how a motor burns up when you push it too far. In the end, the wires burning up caused the ultimate death of the motor, but the root cause was the magnets losing their strength because they got too hot.

{mospagebreak}

Now, having said all that, let's go back to the Scorpion motors. With magnets rated at 200ºC, if you had the same scenario of switching the 10×6 prop to an 11×6 prop, the stator would still be at over 104ºC, but the magnets couldn't care less, because they can happily exist at 200ºC. And since the wire is rated at 180ºC, it is happy to run at 104ºC as well. In fact, in order to cause the catastrophic chain of events to occur as with the earlier motor, the stator core would have to heat up to 180ºC, and the wire would fail first, leaving the magnets intact. Working the numbers backwards, this would require a power level in the stator of 310 watts, which would require a current level of 55.7 amps and a power input level of 557 watts.

Now comparing the two motors -the other Name Brand motor with 80ºC magnets versus the Scorpion motor with its 200ºC magnets – increasing the load of the prop by only 25-30% can quickly cause a thermal run-away condition that results in the complete destruction of the motor with 80ºC magnets. On the other hand, the Scorpion motor, with it's 200ºC rated magnets, can take an overload of 86% and the only thing that happens is that the wire burns out without affecting the magnets at all.

If you pushed the motor that hard, you could re-wind the stator and the motor would be good as new. With the other motor, there would be nothing salvageable other than the metal parts. The motor would need to have all the magnets replaced and be re-wound to get it going again, which is so much work that it would not be worth it.

So there you have it! I know that it was a VERY long explanation, but I think that it was needed to explain the advantage the Scorpion Motors have over every single other motor out there. They truly are a revolutionary product, and the best part of all is that they are about 2/3 the cost of a comparable Hacker motor and only 1/2 the cost of a comparable AXI motor. When you put all that together and add in the 2-year manufacturers warranty that Scorpion has, it is pretty much a no-brainer as to which motor to choose.