Model Forum / Radio Controlled / Land Models / October 2005

Damn, you have a tough life... You MUST build a RC car... most of us
here have it as a hobby :)

For drag, I would try to get away with one motor, 2wd, no diff and a
looooong rail chassis

forget it. Unless you have rules that say you have to run an expensive
piece of crap, take a low-turn modified motor and stuff it in there.

nobody knows, except drag racers. I'm not one of them :)

Another POS. You don't need a diff to go straight.

Preferably lots of them in series and small (=light) cells. But, using
more cells may need a special ESC and motor, so it might take the cost
too high for you.

I have no idea what these are, another Tamiya item?

Well, it'd better have a body of some sort, but if you insist of not
having one, who am I to tell you otherwise :)

It's somewhat unclear to me if you WANT to use this Tamiya cr*p or do
you HAVE to? If you have to, I don't understand your comment about using
2 motors, I'd think your rules would deny using several motors also, if
the type of motor is specified... If you WANT to use this Tamiya cr*p,
you'd better go see a doctor... there are much better options available
and not necessarily more expensive.

BR,
-olev-

...

You might get more current (for a shorter time) out of NiCd batteries
(use lots of small (UM3 or similar), and connect in parallel using good
connection techniques (well welded, or solder to welded tabs).
Also you need a regulator that takes the current (or is running full
speed at all times an option - then use a mechanical switch).

HTH

Marc

Sounds like a school project.  How many of the items you list is rules
mandated, and how much is your idea?

There are vehicles that use 2 motors as you mentioned, but they are all
off-road vehicles.  In a short run I am afraid the weight of the motors
and gearing would waste to much torque.  What surface are you running
on?  Is traction why you want to run two motors?

Gear diffs are to improve turning radius.  Going straight you do not
even need a diff.  Put enough power to the gear diff and as soon as one
tire breaks loose it will spin faster then the other and cause you to
turn.  If rules say you must use the Tamiya diff I would fill it with
hot glue and make a solid axle out of it.  I rules allowed I would run
a solid axle with direct drive.  Mount the spur to the axle, turn it
with the pinion on the motor.  Check out 1/12 pan cars for ideas.  Keep
in mind most of them have ball diffs because they need to turn.  If you
buy one just lock it down.

Do rules force you to use a Stock motor?  40,000 rpm motors are not
uncommon, 26,000 is nothing to brag about.  If you must use that motor
can you mess with it?  If you can you will want to change the timing to
get the best results for your application.  Maybe change the brushes
and get it turned and balanced.

If rules allow, go for foam tires.  If you must use tires listed can
you use more then 2?  Run duals on the rear.  Use traction compound if
allowed.

I would make a lexan shell to smooth the air going over the body.  Also
protect things in case of accident.

Why aluminum?  Carbon fiber or fiberglass sheet will be lighter and
should be strong enough.

As has been stated, NiCd batteries are more powerful when first
charged.  Can also be found cheaper.

Do you need ESC or just a solenoid?  A solenoid would be cheaper.  A
voltage regulator hooked to batteries can power electronics.

If you are going to steer, look for a small servo designed for 1/18
vehicles.  You won't need much steering and want to save weight.

Modern RC Drag Racers run 132 feet, or 40.23 meters. They can do it in
under 2 seconds and hit speeds of over 60mph.  Do a search for RC
electric dragster for more info on their cars.

Good luck and let us know how it works out!