[Konvas] ANY ONE TRY A GYRO STABILISER ? under the camera

[Rick Garbutt]

NEWS BULLETIN !


I got a kit to make my very own one of these YEARS and YEARS ago.

What they are ... what they are, see, are two 400Hz motors with nasty, heavy
(though small) brass flywheels.  Their original use was as bombsight
stabilizer gyros in World War II aircraft.  Surplus value of the motors?
About $20 (that's twenty bucks US$ ) each.  As I recall, the kit was about
US$100.

What that oval "egg" contains is two of them, gimballed so they precess at
90º to each other, thereby providing stabilization in two dimensions.  My
kit contained the bits to make a 400Hz 120VAC power supply that ran off your
own hefty 12VDC battery.  The supply itself was surprisingly small:  about
2" x 2" x 4".  It contained a multivibrator (mechanical), 10:1 stepup
transformer (and the 400Hz ones are FAR smaller than the 60Hz ones, which is
why aircraft commonly use 400Hz equipment like motors and transformers), and
two 2N3055 power transistors, which were heat-sunk to the aluminum project
box.

Funny thing was, if you grabbed the box and touched the outside case of a
2N3055 at the same time, you got a rather unpleasant 120VAC 400Hz shock.  I
doubt the project would meet UL standards for electrical safety.

Electrically and mechanically, though, it all did work.  At the expense of
having some noise associated with it, and considerable weight.

Similar (I'm betting identical) Kenyon motors are also sometimes used as
additional stabilizers on Tyler helicopter mounts.  The rig we rented from
Panavision Calgary for the opening titles I shot for the feature LOST
HOLIDAY had three.  A design feature used here that I'd suggest you
seriously consider was that all the motors were mounted BEHIND the Tyler's
pylon post, on the counterweight end of the floating camera arm.  This is a
brilliant way of using the gyros' own weight to give inertial, as well as
dynamic stability to the camera arm.  [As an aside, I used that Tyler rig
while hanging out the side of a helicopter above the wintery Rocky Mountains
at about 3300m/11,000 feet.  I was under the rotor, and ambient air temp was
-40ºC.  Everything worked just fine.  And I looked like the Michelin Man,
what with 6 layers of arctic underwear, sweaters, and parka.  And I shot
that way for 4 hours.  Wouldn't trade that view for the world!]

For handheld work, you could make a similar rig:  the motors would mount
BEHIND your shoulder on a plate or rail extending back from the camera.
Either way, you could make the gyro mount of a sliding nature to help
precisely balance the camera weight.  You've now turned the cameraman's body
into a human analog of that Tyler pylon.

And as Prof Stone has so ably pointed out:  DON'T mix Steadicam and gyro
gear.  You'll end up having physics fight physics, and you'll be carrying a
LOT of non-functional additional weight.

Best to all,
Rick Garbutt, soc 
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