A Cute Triangle
The Triangle is a
Czech ARF plane. It's super lightweight, with a 24" wingspan,
yet supposedly fully aerobatic.
It has a thick rectangular wing with a fully symmetrical airfoil.
In shape, it's quite a bit like the Lil Hornet,
my favorite plane -- a great aerobat while still a slow flier. My
hope for the Triangle is that it will be a miniature Hornet with an
IPS-class motor: an aerobat for small spaces.
The control linkage is unusual. They recommend using only two
servos, and connecting the rudder to the aileron servo, so that the
rudder is always coordinated with the ailerons. This means no
opposite-rudder maneuvers, of course; but it also means very tight
coordinated turns without needing the weight of an extra servo. I
set it up as recommended, to see whether it worked, and it seemed to
work quite well.
The kit goes together very easily, though the instructions are very
sketchy and the English is poor (in a charming sort of way: "Always
mind the safety of yours and your audience!" The fuselage is a
rather nice tapered diameter carbon fibre tube; the wings and tail
pieces are pre-covered. Just join them with hinge tape, slip the
wings onto the tube, and glue the tail pieces on. The
instructions gave no clue how to mount the engine (a weird but well
made IPS-sized gizmo with a complicated folding prop) or the wheels, so
I ended up using strapping tape. Mounting the servos was a bit
challenging, but that's always true when building planes (does that get
easier eventually?) I used two Cirrus 4.4 oz servos, which
chatter annoyingly but are very small and light, and a GPS Pico
receiver and speed control, and a 700mAh li-po battery. I wanted
to use a smaller battery, but like all planes, the Triangle is set up
for much heavier batteries and it's quite tail-heavy even with my 700
battery. I'm not sure what the total weight is: my hanging postal
scale (0-4 oz) says 3.5 oz, the spring postal scale (0-5 lbs) says 5 oz
It's a lovely gossamer thing; it feels like a sharp glance will rip it
First flight: the outfield of a small baseball diamond
near home. I tried to take off from the infield, but the prop is
too long for the tiny landing gear. (This isn't a problem for
landing, since the prop can fold when the engine is off.) So I
hand-launched it with much trepedation.
No problem! It needed no extra trim, and flew beautifully, making
very sharp turns and needing very little space.
However, the engine is beyond anemic. I spent about a minute
trying to climb to sufficient altitude to try a loop or a roll, and
finally gave up -- I couldn't get the plane higher than about 25'
AGL. It was fun to fly around, and might even be possible indoors
(but our local indoor flying venue was impossibly crowded this week, so
I didn't get a chance to try), but for outdoor aerobatics, it needs
Second outing (after waiting a week for sufficiently calm winds): I
flew a short flight. Dave said incredulously, "Is that full
throttle?" When I admitted it was, he walked over to his Pico
Stick, pulled the IPS off and said "Here, take this. I'll drive
home and grab yours and come right back."
So I taped the IPS-B with the 9070 prop onto the Triangle's stick,
pulling the tape hard so the motor wouldn't shift around too
much. The IPS weighs about the same as the weirdo Czech motor,
but delivers way more pull. Flying with the IPS was worlds better
than with the original motor! The Triangle had no trouble
climbing at steep angles, and I could fly around at 2/3 throttle and
have way more fun than I had with the original motor at full throttle.
The 9x7 prop is way too big for the Triangle's gear, though. So I
got an IPS-1, geared for an 8x6 prop. I cut a motor mount stick
from an old wrecked Pico Stick, and epoxied it into the inside of the
Triangle's fuselage tube. This put the motor slightly farther out
(more nose weight), and not only did the motor and prop work fine, but
the Triangle flew better.
With the IPS, I could climb to sufficient altitude to try some
aerobatics. Loops are a kick! This plane specializes in
tight loops and tight cropduster-style turns. Then I flew up
higher to try a roll ... and discovered that with a gossamer balsa
plane covered in transparent mylar, when you get the plane between you
and the tall trees at the other side of the field, it's impossible to
tell what it's doing or whether it's inverted or not.
Fortunately, the Triangle's incredible responsiveness makes for some
spectacular just-before-it-hits-the-ground heart-pumping saves.
Being more careful about where I flew, I climbed back to altitude and
tried some rolls. Wow! The Triangle whips around in no time
flat with that coordinated aileron and rudder. Snap rolls and
spins are especially fun to watch. The Triangle dances, it
floats, it caprioles. It's wonderfully fun to fly. I just
wish it wasn't so delicate -- it's hard to transport (I need to make a
box for it) and I'm afraid to fly it in wind.
I have no idea why it's called a Triangle. But I think mine's a
cute Triangle! (Har.)
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