From the Eugene Prop Spinners, Eugene, Oregon
Float Flying: a guide to setting up and flying
techniques
by Chuck Hocking
From AMA Insider’s
Technical Editor Ed McCollough:
Chuck Hocking, of the Lakeland R/C Club Inc.,
Oconomowoc, Wisconsin, wrote a primer on float
flying that we are putting in the Insider. Of his
many points, the one that needs a “second opinion”
at the beginning is what he wrote about foam floats,
“… foam (not recommended).”
As it happens, one of my clubs out here (SkyKnights)
has run an annual float-fly that started back in the
1970s or before, depending on which “old timer” is
talking. Sometime along about the 1980s, the big
guns from RCModeler showed up to do a spread about
our float-fly. At that event, they were introduced
to a foam-based float that made all kinds of
airplanes practical and even competitive during the
events. They published the article about us and they
also did a separate piece about what they called
“Hansen’s Floats.”
Just cutting some foam floats out and attaching them
to an airplane won’t do you a lot of good, but a
little work and they can be the best ones for
multi-event meets.
The first thing you do, after you’ve cut the blanks
out of foam, is to split the float lengthwise down
the middle. Next, use one float half to mark two
outlines (one for each float) on some lightweight
plywood or thin laminate. Cut holes in the plywood
but leave the area around the step solid.
At this point you can simply epoxy the lightweight
plywood to one float half and then epoxy the other
float half to make one float. But, to have a much
better float it needs a tad more work.
Before you epoxy the float halves and plywood
together, decide what kind of attachment (and where
you want the attachment) you want to use to fasten
the floats to your aircraft. Small lengths of
hardwood blocks, like maple engine bearers at the
appropriate fastening point, can be epoxied to the
plywood and foam removed from the float-half so all
will fit together. A dowel can be split, for the
same purpose. The bottom of the float needs to be
covered and MonoKote is not recommended!
Aircraft grade ply, say 1/64th-inch thick, can be
epoxied to the bottom of the float. Or, heavier ply
can be used on the front of the float bottom; how
heavy depends on the type of beach you fly from.
Then the bottom could be covered with 3/4 oz.
fiberglass cloth and epoxied on. The entire float
can be finished with any or all of the above. Epoxy
paint is obviously the best, if you want to paint
the floats.
Why all the epoxy? It’s basically waterproof and
“hot stuff” isn’t.
It has been said that one has not
really fully enjoyed RC flying until you have
experienced the thrills and spills of float flying.
Hopefully the following information will be of
assistance to you. Remember these are only presented
as guidelines.
Motor and Propeller: Select a motor that has
sufficient power to get the airplane up on step and
to gain necessary speed for proper liftoff. Remember
it takes more power to lift off of water. Never use
a wooden propeller on a float plane; there is a
possibility that it will shatter when coming in
contact with water.
Types of Floats: There are four basic types
of floats, float kits (which you must build and do
not include mounting hardware), fiberglass,
combination glass and wood, and foam (not
recommended).
Float Length: Guideline—length should be
approximately 75% of body measured from back of
engine thrust plate to end of vertical stabilizer,
plus or minus one to three inches is okay. Too long
can add too much weight; too short will not support
the airplane and not enough float in front of
propeller. Two inches is good.
Tread Width: Guideline—tread width should be
about 25% of wingspan. The wider the width, the more
stable on water. Closer together gives a more scale
look, but will tip over easy in a crosswind. When it
does that, you are done for the day.
Step vs. CG: Guideline—generally speaking,
the step or the center of a V-shaped step should be
in line with the CG of the airplane. I have found
that 1/2 inch either way causes no problem.
Incidence: Critical—incidence must be about
1.5 positive degrees when the top of the floats are
level. More than that will cause a premature takeoff
before necessary speed is reached. Less than that
and the airplane will probably not lift off. You
will now have a high-speed boat with wings on it.
You will need a Robart Incidence meter to do the job
correctly. This is the most important step in
setting up your floats.
Alignment: Critical—in the final assembly be
sure both floats are parallel with each other and
parallel with the center line or thrust line of the
airplane.
Rudder: Guideline—I feel, if possible, a
servo-type rudder is the best choice. It gives a
more positive type action and is trouble free,
especially if you will be going back and forth
between floats and wheels. If, however, you will be
setting up your airplane for float flying only, then
an extra rudder horn and cable will work just fine.
I hope this information will be of assistance to you
in setting up and enjoying your airplane.
Q
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