with success in the Weta kits I built
I finally was forced to make a
change this year when my supply of
the 28-35 motors ran out and I could
not find a replacement that was not a
lot heavier. I decided to move to using
one of the lighter beater bars so I
could use one of the heavier motors.
This brings us back to the Er = ½Iw2
I wanted to maximize E but was
reducing I, which just left me with
increasing w if I wanted to have equal
or even greater energy than before.
One advantage of increasing the
rotational velocity of the beater is that
Er increases by the square of w, so
even a modest increase in the RPM of
the beater gives a sizable increase in
the energy available for a hit.
I had bought a number of Turnigy
2845 5,500 kV motors (Figure 2) for
using in my kits, but the current draw
had proved too much for the batteries
available at the time. I had been
forced to use the somewhat tamer
4,400 kV versions in customer bots.
I decided to try again with the
5,500 kV motors in Weta, this time
using a new 70C 850 mAh battery
SERVO 10.2014 19
Figure 2. 5,500 kV motor. Figure 3. Sharpening the teeth. Figure 4. Split pin secures axle.
Figure 5. Nut and bolt at the other end. Figure 6. Larger setscrew in pulley. Figure 7. Motor installed.
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