Flipper (and Fifi): EPP 3D
"3D" is the
term for aerobatics in a very small
space: hovering an airplane by hanging off the prop, doing torque
maneuvers such as lomçevaks and waterfalls, and generally flying
ways which rely on engine torque as much as (or more than) wing lift.
built a small (24" wingspan) 3D aerobat out of expanded
(EPP) packing foam, and he's been doing crazy aerobatics in
the street in front of the house. Because EPP is fairly rugged,
the plane is relatively resistant to damage; and because it has huge
control surfaces and is fairly small and lightweight, it can do wild
maneuvers in a small space.
The neighbor's dogs don't like the sound of the Feigao motor, and start
barking when they hear it. That brings the neighbors out to
watch; occasionally we get a big audience, and they applaud when the
lands. Since it has wheels, it can fly off an asphalt surface
without having to worry about catching it, and it can taxi around (most
of our planes don't have wheels and need to land on grass or other
Cool! Of course, I had to have
We got the
sheets of 7mm EPP foam from Slowfly.
(Don't take that 7mm as gospel; actual thickness varies
considerably.) Design was somewhat similar to my Edge in basic size and wing conformation, but
with much bigger ailerons (the Edge is a wonderful aerobat but doesn't
have quite enough control surface for 3-D maneuvers), a full-flying
elevator, a crossed fuselage (both horizontal and vertical pieces, as
pioneered in the famous Shock Flyer series), and wheels (with carbon
fiber gear). Most of the stiffening comes from thin carbon fiber
strips along the edges of the foam, not from the usual CF rods embedded
in the foam. I used "canopy glue" (a lightweight and somewhat
flexible white glue) for most joints; it's one of the few glues which
will work on EPP. Dave is gradually building a construction
Since EPP is
like Teflon and nothing
sticks to it -- no stickers, and paint doesn't work well either -- the
best way to decorate is with magic markers. I put color on the
top side, none on the bottom side, so I can judge the plane's
orientation when it comes out of a wild maneuver. Unfortunately,
the EPP is a little transparent, so when the sun shines through it,
you can still see some color underneath; but
it's still pretty easy to tell which side is up, as you can see from
these shots of Flipper's underbelly.
Final weight is 5.3 oz without battery; a 730 mAh li-po battery takes
to 7 oz.
The power plant is a Feigao brushless motor in a GWS IPS-B
gearbox. Dave is using an IPS-C gearbox, which gives slightly
better pull at slower speeds, but requires a larger prop and is a bit
more difficult to hover due to the increased torque effect.
a great 3-D trainer! It doesn't fly level very well at all
-- it's not a good general-purpose aerobatic plane like the seemingly
similar Edge -- but it's excellent at wild
tight loops, hovering, extreme slow flying and harrier landings.
It has a steerable tailwheel, so it taxis, takes off, and lands nicely,
which is fun since most of my planes don't have landing gear.
Despite the floppiness of EPP, the carbon fiber keeps it stiff enough
that it's very responsive in the air, even if has too much drag to fly
like a normal plane. Recovery from near-crashes is very quick,
which is helpful for someone like me who's just learning 3-D flying.
EPP foamie is named "Fifi" because the swirly EPP makes the
plane look like a poodle. Mine is named Flipper, because the
front of the fuselage came out looking a bit like a dolphin's melon.
And it flips around pretty nicely in the air!
Notice the red bit in front of the tail in the photo at left.
That's a piece of Zagi tape I stuck to the wing to on the first flight
to try to decorate the plane and make it
easier to tell top from bottom. Remember how I mentioned that
nothing sticks to EPP? The tape came unstuck as soon as the plane
hit the air, got blown back and ended up stuck to the rudder pushrod.
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