Man-Carrying R/C Pattern Ship
If you ever want to know exactly how the little plastic pilot in an R/C
pattern ship feels, go strap on an Edge 540. In truth, no 1:1 scale airplanes
give the three-dimensional freedom a pattern ship has because of the power-to-weight
ratio, but the Edge comes terribly close.
The Bill and Judy Zivko Edge series of airplanes are serious unlimited
competitors. The very fact that National Champion Kirby Chambliss flies
an Edge speaks volumes for the airplanes. The Edge’s are right at
the leading edge (hence the name) of aerobatic technology.
To anyone used to flying general aviation airplanes, the Edge 540 is going
to feel scary, if nothing else because it has no “feel”—there
are virtually no pressures at all on the control stick. These kinds of
control forces have become standard for unlimited aerobatic birds. It
could easily be said that you feel more pressure with your thumb on an
R/C joy stick than you do on an Edge control stick. The results, however,
are much more numbing. No one’s ever burst blood vessels in their
eyes while flying R/C, although a few of us have felt like vomiting after
stuffing a prized bird in.
When talking about control feel in a real airplane there are three factors
that have to be considered. First is the breakout force—how hard
do you have to push to get the stick started out of center? This is what
determines the self-centering characteristics of the controls. Second
is the stick force gradient—once the controls are off center, how
much does the force increase the further you displace it? And third is
the acceleration—how quickly does the airplane leave level flight
and assume the roll or pitch rate that amount of control displacement
In most airplanes the centering (break out) force is enough to let you
find center and the controls get heavier the further you move them. Plus,
most airplanes have a perceptible time lag between control displacement
and airplane acceleration.
All of this tech talk is well and good, but it doesn’t mean squat
in an Edge. There are no centering forces. The only way you know the controls
are in the center is the airplane isn’t moving on way or the other.
And the controls don’t ever change pressure—full aileron feels
just like a tiny bit of aileron, except your head is bouncing off the
canopy because the airplane doesn’t hesitate a nanosecond before
The first time I visited Bill and Judy at their plant in Guthrie, Oklahoma
and they strapped me into a 540, I thought I was prepared, but I wasn’t.
About all my many thousands of Pitts hours did for me was ensure a safe
landing. The Zivko is so light on the controls and so incredibly quick
to respond that it made my lovely little Pitts feel like a dump truck.
A very creaky, over-loaded dump truck.
For one thing, the Edge rolls at over 400 degrees per second. That means
it takes less than .9 second to do a complete roll and, when this is coupled
with zero control pressures, initially just level flight becomes a chore.
The first time I cranked it inverted and pushed into an outside loop from
the bottom, I inadvertently slammed six negative G’s on myself when
I was only looking for four—the amount of pressure it takes to push
(stick force per G) was just as low outside as it was inside, which is
to say, it was close to zero. Just push and it goes around.
It would take a book, or better yet, a video to adequately describe what
forty-five minutes of yanking and banking in an Edge is like. Unfortunately,
as hard as I try to describe it, in reality, only the plastic guy in your
pattern bird can truly understand what I’m talking about.
Peanut Pirep? Return to PEANUT.