"Phil Kangas" wrote in message
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"Stu Fields" wrote in message
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"RogerN" wrote in message
m...

"Stu Fields" wrote in message
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"Roger Haar" wrote in

Roger: You are dead right. On the Helicopter, the first move is to
track the blades. aerodynamically. Out of track blades on the helo
will cause a 1/rev vertical vibration that can confuse a balancing
operation if the operator isn't paying attention.
On our ship we put two different color grease pencil marks on each
blade. When the rotor is spun to full speed, my wife takes a pole with
the center cardboard tube from a paper towel roll attached to the top
of the pole and carefully brings the paper towel roll in until it just
ticks the blade ends. We get two different color tick marks of one
blade is higher than the other. We adjust until we get just one color
combined from the two. This doesn't guarantee good aerodynamic tracking
at cruise speed on the helo since aerodyanic differences of the two
blades can cause a "climbing" blade. Helps to have a fearless wife...


I do something sort of similar on my R/C helicopters. I use 2 different
color tape strips near the tip of each blade, hover the helicopter and
look at it from the side, you can see if one color of tape is flying
higher than the other. When the blades are out of track it causes a lot
of vibration.

RogerN

With our bigger ships, a tracking tip light was invented where you
install a red LED on one blade tip and a white LED on the other. The
LEDs are pointed at the pilot. The first time I tried these, I was
nervous about them coming off in flight and creating a hellatious
vibration. While running up I noticed a red streak and a white streak
and thought "This is Great". Then at flight rpm the lights disappeared.
No vibration so they must have both left at the same time. Slowed back
down and there the lights were again. Great design. Centrifugal force
pulled the little battery away from the LED. Tremendous idea though. It
eliminated the need for a passenger operating a strobe light to check
track during cruising flite. One design used centrifugal force to turn
the LEDs on...

Perhaps you are refering to 'centrifugal reaction' ? ;))
Sorry, couldn't resist.... phil

You're right. It is just a habit I've picked up reading Baumeister and
Marks Mechanical Engineering Handbook where they refer to the definition of
centrifugal force on page 3-25. Ir does remain a useful concept.