After about a 12-month hiatus from flying
any kind of model airplane, and having sold all of my RC gear prior to moving to
Erie, PA, I looked around for something that would get me back into the air quickly.
My first inclination was to build yet another
Spirit 2-meter sailplane and
put a brushless motor in it like before, but I really didn't want to have to take
the time to build it first. I also did not particularly care for most of the ARF
gliders that were available, but seeing the
ParkZone Radian sailplane on the Horizon Hobby website and watching the video of its flight
convinced me to spring the $250 for the RTF version. There certainly is no better
value out there - a nice-looking sailplane with brushless motor and controller,
servos, a 3-cell Li-Po battery, and a charger, along with a 2.4 GHz spread spectrum
radio system. You cannot buy the parts individually for that much.
was a piece of cake - just slide the horizontal stabilizer / elevator into place
and secure it with the supplied clear tape, then connect the pushrod wire to the
control horn. I didn't like the way the straight wire put a twist on the control
horn, so I bent an offset into it to relieve the strain. The pushrod is plenty stiff
to function with the bends. The four AA alkaline batteries were installed into the
transmitter, the Li-Po was charged (only took about 15 minutes), and off I went
to the flying field.
The recommended range check was performed on the radio, and controls were verified
to be moving in the right direction. I slowly revved the motor up to about half
throttle and launched the Radian into about a 5 mph wind and away she went. At about
3/4 throttle, the Radian will climb nearly vertically. It has a strong nose up tendency
at more than about half throttle, so a significant amount of down elevator is needed
to keep it from literally climbing into a straight up attitude. This can be a bit
of a pain at altitude. A computer transmitter would be of great benefit because
you could program in down elevator as the throttle is advanced. But, for a $100
savings, I'll feed in the down elevator myself (at least for now).).
I have to say that this Radian is the best 2-meter sailplane I have ever flown.
It is amazingly stable even in gusty conditions, and floats like a butterfly in
calm air. Each flight has lasted well over 30 minutes, and that is without coming
anywhere near depleting the Li-Po battery; it typically has 11.5 V of charge left
after flying around for 45 minutes to an hour. One time when I was flying over a
school building and parking lot, I got over 30 minutes just on thermal lift alone
- a record for me. The Radian was so high and in such a strong thermal that I put
it into a spin to lose altitude. then, she went right back up again. That was at
around 2:00 on a Saturday afternoon. I sure wished I had installed myI have to say
that this Radian is the best 2-meter sailplane I have ever flown. It is amazingly
stable even in gusty conditions, and floats like a butterfly in calm air. Each flight
has lasted well over 30 minutes, and that is without coming anywhere near depleting
the Li-Po battery; it typically has 11.5 V of charge left after flying around for
45 minutes to an hour. One time when I was flying over a school building and parking
lot, I got over 30 minutes just on thermal lift alone - a record for me. The Radian
was so high and in such a strong thermal that I put it into a spin to lose altitude.
then, she went right back up again. That was at around 2:00 on a Saturday afternoon.
I sure wished I had installed my HowHigh™ altimeter. It was so high
that I could barely tell which way it was going.
My next trip out did not turn out so well. After flying around in weak evening
lift, I decided to do some precision landing practice (which for me is landing within
about 20 feet of the target area). On what was intended to be the last flight of
the evening - and turned out to be so anyway - I launched as usual, then decided
to do a full throttle climb-out. I had never had the Radian at full throttle, even
just running it up on the ground. I eased in the juice and began to pull up vertically,
when all of a sudden the canopy flew off and I heard a gosh-awful noise coming from
it. I immediately throttled back, recovered from the stall, and circled back to
the ground while keeping my eye on the descending canopy. I didn't know what happened.
Upon landing, an inspection of the craft showed that one side of he folding propeller
had broken off about an inch past the hinge point. Evidently the prop broke and
the ensuing vibration shook off the canopy.
After getting home and pondering the situation, I decided to do a Web search
to see if anyone else had reported such an occurrence. Well, it turns out that the
Radians have had this issue since at least January of this year (2009). All have
reported the exact same failure mode (see
RC GroupsRC Universe).
I contacted Horizon Hobby about it and the guys who wrote back (Nathan) said that
ParkZone is aware of the problem and is working on a fix. This kind of a known failure
mode that throws a thin, sharp blade seems like a lawsuit waiting to happen. I hope
the fix it quickly and send out replacement props to all current owners, or at least
broadcast a willingness to do so. It wouldn't be hard to find a large number of
witnesses for convincing a jury of the negligence.
Here are a few photos of my broken Radian folding propeller blade. It's hard
to tell from the pictures, but the break is clean along the cord. I did not recover
the piece that separated, so I cannot tell whether it broke into more than two pieces.
Amazingly, someone captured an in-flight video of a prop breaking
on the Radian during a climb-out
September 7, 2009 Update:
Well, the new propeller was installed and the Radian is flying again. With the
Winged Shadow Systems' HowHigh electronics altimeter installed, I launched the Radian
Erie Tech Center flying site. After a powered climb to a couple
hundred feet, I began searching for a thermal. It did not take long to find a boomer.
In no time, the Radian was a small dot in the sky. My no-so-great eyesight caused
me to to abandon the thermal and land to see how high it got. 1,122 feet, per the
HowHigh. The altimeter was reset and up she went again. This time the Radian made
964 feet. Nice. I spent about 10 minutes just launching to about 50 feet and practicing
landings. There is one spot at the south end of the approach that would be ideal
for a hand-launched glider (HLG), because is seems every time I pass over it at
low altitude I can circle a few times before landing.
Here is a little exercise to figure out just how big a 2-meter wingspan looks
at 1,122 feet. The first step is to figure out how far away the Radian is. I estimate
the Radian was about 20° off my vertical, so by the trigonometric
relationship shown to the right, that makes the Radian 1,194' away (only about a
6.4% increase over vertical). So, the next thing to do is calculate how big
the wing looks at that distance. Again, trig is used to calculate a subtended angle
of around 0.33°. How big is that? Well, the sun and moon subtend angles of about
0.5°, so the Radian appeared roughly 2/3 the size of the sun.
Posted December 9, 2022 (updated from original post on 9/17/2013)
About Airplanes & Rockets
Carpe Diem! (Seize the Day!)
Even during the busiest times of my life I have endeavored to maintain some form
of model building activity. This site has been created to help me chronicle my journey
through a lifelong involvement in model aviation, which
all began in Mayo, MD
Copyright 1996 - 2026
All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the Airplanes and Rockets website are hereby acknowledged.