NetNews Usenet Archive 1993 #3/NN_1993_3.iso/spool/rec/models/rc/5722

Text File | 1993-01-25 | 7.1 KB | 123 lines

Newsgroups: rec.models.rc
Path: sparky!uunet!panther!mothost!lmpsbbs!bobwo
From: [e-mail] (Bob Woodhouse)
Subject: Re: Modified? (Was: Re: Misc R/C Car Questions)
Organization: secure_comm
Date: Mon, 25 Jan 1993 13:17:53 GMT
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>>This makes me (an airplane person) wonder:  Just what does "modified"
>>mean (as applied to car motors)?  Apparently if I talk a motor and
>>modify it, it is not necessarily "modified".  Similarly, I can buy
>>a motor off the shelf, do nothing to it, and it can be "modified"
>>anyway.
>>
>>Can anyone explain?

    [some deletion]

>    There's a guy who all the electric airplane guys know named Bob Boucher
>    who owns Astro Flight. Astro Flight makes a wide variety of modern motors
>    including an "05" size that is very similar in appearence to the Mabuchi
>    "540". The Astro "05" is superior in every way to the Mabuchi "540" and
>    retails for the same price as a top-line "modified" Mabuchi. The big
>    difference is that it costs Bob Boucher more than 10 bucks to build one
>    of his "05"'s, so there's not nearly as much profit in building 10-dollar
>    motors as there is in importing crummy $2.00 ferrite "540-type" motors
>    and reselling them. There is also the fact that Bob Boucher isn't one of
>    the guys who built an organization like ROAR. As an aside, it turns out
>    that Bob Boucher was influential in supporting the organizations that
>    santion R/C drag races and truck pulls. In those types of competition,
>    and an Astro Flight motor is "the one to beat".
>
     [more deletion]
>
>    What I object to is the fact that hell is going to freeze over before
>    organized racing allows me to use a sturdy, well-built motor that is
>    going to last a long time and run the car as fast as I would like  to go.
>    The people I race with every week seem to be convinced that just because
>    they pay around $50.00 for a motor, it is really "state-of-the-art" and
>    nothing better exists in the whole universe. In reality, they are using
>    motors that were desgined as cheap throwaways nearly 20 years ago. If Bob
>    Boucher could sell Astro Cobalt 05 motors in 1/10th of the quantity that
>    Trinity sells Mabuchi ferrites, you could buy a motor for $50.00 that
>    would produce 50% more output on the same amount of battery juice as a
>    current top-line ROAR-legal modified and would last almost forever with
>    a reasonable amount of care.

It turns out that I have been wanting to try an Astroflite motor in my 1/10
scale 2wd buggy for some time.  The turbo 05 seems like a reasonable choice
(versus the Top Fuel I or II) for this application.  When I last spoke with Bob,
he said that you could think of the 6-turn 7-slot armature as being a 6X7 = 42
turn-of-wire motor which can be roughly equated to a 42/3 = 14 turn ROAR-type
motor.  Astrflite also sells a 5-turn armature which will fit the turbo 05
and behave similar to a ROAR 7X5/3 = 11.6 turn motor as far as gearing would go.
Now 11.6 turns is my kind of off-road motor, but it looks like I would have to
buy the turbo 05 at $54 and the extra armatur at whatever (not too bad).  I had
dismissed the idea of buying the motor because, just like everything else that
I race (a Schumacher CougarII with Hyperdrive belt system) spares and replacement
parts (brushes) would not be at my race track store.  However, now that my "Reedy
12-turn" motor (my only race motor) is on its last possible commutator truing,
I am forced to spend bucks anyway.  The other dilema is that the Astroflite motor
is not allowed under ROAR rules, which apply at my track.  One thought that occured
to me is that I could get the turbo 05 with the extra armature and have ~ 11.6 and
14 turn type speed and acceleration, and then I could get an 11 or 12 turn ROAR
type motor for actually racing.  Why, you ask -- well, if it is true that the
Astroflite motor and brushes last much longer than a ROAR motor, then I could practice
with the Astroflite motor, and give the ROAR motor a break.  I wonder if Mr. Hutto
has just found an excuse to buy the turbo 05.

As long as we're talking about motors, let me pass on a simple, but useful technique
for attaching motor brushes to ROAR motors.  Some brushes come with eyelets and
are screwed onto the motor can.  I like this technique, but my favorite brush is
the Reedy off-road brush, which has no eyelet and is intended to be soldered in place.
I don't like having to depend upon having a hot soldering iron always at the ready
(I use connectors between the speed controller and batteries and motor (just think
of ALL that power loss)), especially if I am racing on a parking lot without elecricity
and I don't have a butane soldering iron with me.  So what I tried to my liking is
to take the Reedy brush and wrap the end 1/2 to 3/4 of the way around a skinny screwdriver
so that the little hook will fit nicely around the eyelet screw, then, just as in
household wiring, put the hook of wire under the screw and screw it down.  No soldering
is required, and it works well.  Be careful not to put too much wire under the
screw because the wire is short already and you could run into trouble with the
brush being limited in travel.

>
>    Finally, a few comments about "stock" class competition as it now exists.
>    The alleged reasons for having a "stock" class are: 1) everyone's motor
>    will have the same power, making competition more even, and 2) to keep
>    the cost of racing down. Setting up this sort of class works for a while,
>    but years ago it developed to the point where the "stock" motors on the
>    approved list are purpose built. If you showed up to race with a Mabuchi
>    "540" motor (like comes with many R/C car kits) in the "stock" class at
>    your local track, your car couldn't do 10 laps in the same four minutes
>    that the other cars to do 15. To compete, you had better buy a "real"
>    "stock" motor for around 20 bucks. OK, you do that and now you can do 12
>    laps in the time the other "stock"-class cars to 15. Even among the
>    faster cars, some of them can pull away by 10 feet on a 100-foot straight
>    compared to the others. Hmmm, it seems like some of these "stock" motors
>    are more equal than others.
>

It is rather amusing when you see ads for the latest in stock motor technology.
Our newest motor now has a SHORT STACK and 5.0 MAGNETS and SMALLER COILS to
get away with LESS WIRE.  It's like all the modifications are being done for you
on your stock motors.  When I started racing in August 1992, I went right to
modified motors mainly because my previous 3 months of experience on parking lots
showed that if crud gets in a stock motor, then it is hard to get the crud out;
whereas, with a "modified motor, you can open the thing right up.  I don't
know what the attraction of a stock motor is other than its low price for the
beginner.

>
>-------------------------------
>Brent Hutto
>[e-mail]

Bob Woodhouse
[e-mail]