Page 17 - MFW Dec 2024

A proper pre-rotator Trial 4
I found an O-ring size that would work as a friction-drive Back to the field! While it was definitely easier to see, I still
tyre and printed a matching wheel to fit to the rotorhead. I had to cope with the bumpy surface and identify and react
designed a suitable motor mounting bracket that pivoted to the signals. The next attempts resulted in a couple more
behind the rotor axis and swung the bare motor shaft into flips and another wrecked set of rotor blades. Never mind,
contact with the front of the tyre. It connected to a servo on I’d always expected to go through a few before I mastered
the rotorhead via a simple wire spring that provided the technique! I was just glad the long grass beside the
pressure against the tyre, leaving spare servo travel to runway had limited damage to other parts. Meanwhile I
allow for wear. A second ESC connected to the main was constantly refining the blade manufacturing process
battery. The device was linked to the momentary switch on and printing modified versions of the tools as I thought of
the transmitter and the pivoting arm set to engage slowly. better ways to do things, so it became easier each time.
The motor start was Hours of sanding was probably good exercise for my
delayed until the motor inexplicably expanding tummy too…
shaft was about to
contact the tyre, at Further trials
which point it gradually This was taking longer than I had expected! More failures
revved up to full speed were captured on video and frame-by-frame analysis
o v e r a b o u t e i g h t showed the coiled nosewheel spring was one culprit. At
seconds; it was just a speed it was folding under to the left. On recovery it loaded
matter of holding the the left main spring which bounced back onto the front
switch until the blades spring and initiated a bigger oscillation that resulted in a
were up to speed. It couple of forward rolls to the right. As the two oscillations
worked perfectly from took only fifteen frames of video, or half a second, it was no
the start and allowed me wonder I couldn’t react quickly enough! Rebuilding and a
to stand in the pilot’s box new front spring design followed, Murphy naturally
where I could more dictating that my printer should go on strike right when it
clearly see what the was required to print a raft of new parts. I also increased
gyro was doing and the rotor diameter again.
( h o p e f u l l y ! ) a c t
Pre-rotator. Wheel with O-ring tyre, accordingly. Re-design time
motor on arm pivoted at rear (above
wires) servo (left) to pull wire spring The revised front end was an improvement and I think the
(around motor) & move motor onto tyre. model may have been flyable from a sealed runway if I’d

For details contact: Gavin Shute 021 656 999 or gavinshute@gmail.com
For details contact: Gavin Shute 021 656 999 or gavinshute@gmail.com
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