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Here is a short clip of the
1st flight |
My
Li'l Poke uses a Great Planes ElectriFly 4CH FM receiver with an ElectriFly
C-10 electronics speed control (ESC), two Hobbico CS-5 Nano servos (rudder
and elevator),
a Futaba S3106 servo (aileron), and a Great Planes ElectriFly
T-280GD Park Flyer Motor System. For now, it will use an 8-cell NiMH, 650
mAh battery pack. Final weight is 13.4 ounces (advertised is 12.5 - 14.5
oz). See detailed photographs below.
On
Sunday, February 19, 2006, I finally, after four months of building, took it
out for its maiden flight. After exercising due diligence with range
checking, battery tests, control checks, etc., I confidently took off. The Li'l Poke tracked straight as an arrow and lifted off beautifully. In the
first turn I noticed what seemed like a momentary loss of control, but
figured maybe the excitement of flying a new plane clouded my judgment.
After another turn, it happened again and I knew something was wrong. At an
altitude of about 100 feet, I turned to land and the plane literally dropped
out of the sky and headed straight down. By some miracle, when it was about
15 feet off the ground, I regained control and landed with a hard thud, and
no visible damage.
|
FCC Compliance |
Whenever
a device that emits radiation (intentionally or unintentionally)
is
to be licensed, test results from an approved testing facility must be submitted
to prove compliance. Along with the numerical results, internal and external
images are submitted. Clicking on the two image to the right will open the
FCC documents with full-size versions. |
Some post-flight testing revealed that the receiver exhibits
an almost total signal null at a couple different transmitter (Futaba 6 ch)
antenna positions. It does not matter whether the Tx antenna is collapsed or
fully extended. As a 30-year RC flyer, I know how to properly install a
radio system in an airplane (and helicopters) and extend the antenna outside
the aircraft. I have never seen anything like this complete loss of signal
with certain transmitter antenna positions. What it tells me is that the
receiver is woefully inadequately designed or it is the victim of very poor
manufacturing quality. In the future, I will stick with Futaba radio gear
exclusively, since in over 20 years of using it I have never had any kind of
failure.
Stay tuned... One of the new
Spektrum DX6 spread spectrum RC systems (from
Horizon Hobby)
operating at 2.4 GHz has been ordered and will be installed in the Li'l Poke. The system has a dual
redundant transmit/receive scheme with interference-free operation. Update: the Spektrum DX6 radio
was installed and has been working flawlessly - absolutely no interference problems. I've has the
Li'l Poke up probably 500-600 feet to do spins, and have never had any loss of control. This is a
great system!!!
Here are a series of
detail photos that show radio and motor installation,
as well as some shots of the pushrod and control horn hookups. Covering was
Coverite Coverlite with Balsarite adhesive. The Coverlite covering is
unbelievably strong for its weight - it is even hard to tear on purpose. The
only aspect I do not like about using it is having to paint on the Balsarite
adhesive (the covering does not come with adhesive applied). The
inconvenience is that every place the covering needs to overlap, you need to
paint a line of adhesive where the overlap will occur. Consequently, you
cannot the tops, bottoms and sides of areas in a single session. Another
really nice feature of the Coverlite is that it stretches and shrinks
extremely well with both an iron and the heat gun. I was able to cover the
compound curves of the turtle deck and wingtips in single pieces (per side)
without any wrinkles - amazing!
 


  
Note: The ailerons proved to be almost totally ineffective, so I decided to remove the servo
to save weight, and glued the ailerons in place. They could be cut back out and used again, but it
really is not worth the trouble.
The
first frame pictures are available now. Lightening holes were drilled in all
the wing ribs, and lightening holes were cut in the fuselage. There just did
not seem to be a good reason to have that balsa sitting there just adding
weight. I have to say that Great Planes did not do a particularly good job
engineering this kit. Fuselage side lengths matched the plans when flat, but
ended up short when curved as they actually go together. The polyhedral
joints are implemented very stupidly. Only the root rib for the outboard
panel is slanted to accommodate the dihedral, rather than dividing the slant
between the center section end rib and the outboard section root rib. What
happens is that the root rib for the outboard section is necessarily taller
than the others because its length is that of the hypotenuse of a right
triangle. That means when the two wing sections are butted together for
gluing, there is a about a 3/32" high step at the joint. As I said - really
stupid. It caused me to have to add a strip of balsa in from TE (trailing
edge) to LE (leading edge) to smooth the transition. The other unforgivable
blunder is that the plans show the bottom TE balsa sheeting in
the wrong
location. It actually sits about 1/8" closer to the LE than what is shown.
Although not called for, I decided to add some 1/32" stiffeners to the open
areas between the ribs on the wing TE and the front of the ailerons because
leaving them open creates an very weak and crush-prone edge. I can't imagine
why GP does not do that. Finally, I chose to use a DuBro miniature tail skid
instead of the one built out of 1/8" square balsa per the plans. That balsa
version, even when saturated with CA, cannot last long. The entire frame has
been coated with CoverRite's BalsaRite, in preparation for covering with
CoverLight.
Earlier Post: There is an interesting story to go with it already, though. First, I'll say
that of the many Great Planes kits I have built in the last decade, all have had very good quality
balsa, bass and plywood. Their hardware I have never particularly cared for. Anyway, the Lil' Poke
is a backyard flyer and thus should be constructed of lightweight balsa. Well, all three 1/16" rib
sheets and the two 1/16" fuselage side sheets were the hardest balsa I have ever seen anywhere. It
was harder than the stuff that used to come with the Guillows free flight rubber kits. In fact, I
weighed it on a postal scale an calculated the density to be 18.3 lb/in³ - off the charts
for balsa density! Medium density balsa is 6 lbs/ft³. Tower Hobbies
replaced the sheets on request, so I'm satisfied. I offered to return the
original sheets to them, but they did not want them. The recommended
motor/gearbox and airborne flight pack were ordered to go with it.
Here's a handy trick I just discovered: While cutting and sanding the many
balsa sticks that make up the Lil' Poke, many times I end up sanding off
just a tiny bit too much to get that perfect fit. The old carpenter's joke
that, "I've cut the end of the board off three times now and it's still
short," actually has a cure now for this application: Dip one or both tips
of the balsa stick in a drop of water to get just the right amount of
swelling. Pin the stick in place and let it dry, and viola! Perfect fit! |