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Newsletter / Ezine

- RC Cars Ezine 10

RC Cars Ezine 10

RCCARTIPS.com Newsletter / Ezine

Reading Time ~ 3 minutes

Vol 1, Issue 10      Subscribers: 563      August 6, 2003


* Electric RC Motors
* Traxxas Rustler Electric Off-Road Truck
* Updated Links
* Refer Your Friends



Hi again. You may have noticed that my monthly newsletter is
now a weekly one. This is because I am excited about rc cars,
and cannot wait one month to write about them.

This week I would like to discuss electric motors. I chose this
topic because I was reading a 1986 Tamiya RC Catalog and
stumbled upon an interesting fact regarding the Mabuchi RS-540S

Ok, for the experts in this mailing list, what is the torque of the
Mabuchi 540? And while you're at it, what is the torque rating
of the Mabuchi 380S motor?

And the answer is...

Mabuchi RS-540S
Torque: 200gcm
RPM: 11,000
Current draw: 6.25 amperes

Mabuchi RS-380S
Torque: 75gcm
RPM: 12,800
Current draw: 2.9 amperes

A car with the 540 will be much faster than a car with the 380,
despite the fact that the 380 has a higher rpm (i.e. rpm is not
the sole factor in determining the speed of a motor).

Let's relate to actual rc cars. The HPI Dash uses a 380 motor,
and has a speed of around 12 mph. My Tamiya Mercedes
Benz SLK has an estimated top speed of 17 mph using a
540 motor.

Today, a lot of ready to run electric rc cars from companies
such as HPI and Traxxas use a 20-turn motor. These provide
about 20% more power than a Mabuchi 540.

For example, the HPI Sprint has a top speed of 22 mph, while
the Traxxas 4-TEC has a top speed of 21.5 mph. Both these
cars use a 20-turn motor.

Now, power has its trade-off. More power means shorter
running time. For example, typical run times are:

Mabuchi 380: around 20 minutes
Mabuchi 540: around 10 minutes
20-turn motor: around 6 to 8 minutes

So far, we have been looking "stock" motors (although some do
not consider the 20-turn to be stock). When I was racing in
the early 90's, there was a "stock" class and a "modified" class.

The stock class allowed us to use a 24-degree stock motor.
Note that degree and turns have different meanings. Degree refers
to the angle offset of the brushes relative to the magnets inside
the motor. Turns refer to the number of times a wire is wound
around one of the poles of the armature. An armature usually
has 3 poles.

From my experience, the 24-degree stock motor seemed to 
provide at least a 30% power increase over the Mabuchi 540.

The modified class allowed low-turn motors (e.g. 10 turns) and
these motors have end bells that allow you to disassemble the
motor to clean the armature, brushes, bearings, and magnets.

Modified motors can push a car over 30 mph, and even 40 mph.

Whew, so many motors to choose from. For beginners, I strongly
recommend you stick with the Mabuchi 540 or the 20-turn
stock motor that comes with your car or truck. Practice until
you are in full control of the car, even at full speed. I still 
remember the many times I crashed and damaged my car even
though it was "only" using a stock motor.

You can really have lots of fun with the stock motor. If you have
the chance, join or watch a Tamiya Championship race. There
are racing class where the motor to be used is a Mabuchi 540. I
have been fortunate enough to participate in the Tamiya races,
and let me tell you it is fun. Cars are evenly matched, and the
racing is fun and exciting.

You might find it hard to believe, but I still have fun playing with
rc cars using just a Mabuchi 540 motor. This despite my
experience in racing nitro powered touring cars that exceed
40 mph. To me, it is not how fast you go, but how mentally
involved your mind is in imagining you are driving and racing a
real car.


21 mph, 20-turn motor

A good starter car is actually an off-road electric truck like the
Traxxas Rustler. This is because trucks allow you to jump ramps
and play in the dirt, such as baseball fields, BMX tracks, and
the beach.




Secrets of Nitro RC Cars eBook (downloaded over 500 times)

Traxxas RTR Cars

Traxxas Rustler

Team Associated

Past Issues

Your Own RC Car



I have been happily playing and racing rc cars for the past 25 
years. And I know of people who have been enjoying the hobby
for longer than I have.

You can help grow the hobby by forwarding this email to two of
your friends. I will do my best to make the hobby easy to learn
and get into for them.

Thank you for reading. Peace!

Joel M.

P.S. Thanks for forwarding this email :)

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