dragon_not_fly
Heliman
Location: US
My Posts This: Topic Forum | The Nickel Metal Hydride Wall...In my opinion, electric power systems(EPS), are not
"plug n' play" by any means. I think this is a bold state-
ment, but true from experiences with EPS and the Walkera
DragonFly #4. Everyone knows who use EPS or from now
on electric powered r/c products, that in theory, all you need
to do is to charge battery(s) and then go run or fly. So, EPS
is clean, quiet and easy to operate. I believe this to be largely
true, but there is, in my opinion, a very unfriendly side to electric
power and that is setting up a system for maximum efficiency; this
is anything but simple or easy. Below you will see why.
[2 minutes 17 seconds of hovering power]
On the 61 first flight of my Feigao brushless tail motor, I have docu-
mented all of them and at the time of the writing of this post I have
exactly 80 flights on the same Feigao brushless tail motor and it
is still as strong as the day when I purchased it, with my then current
setup I was only able to maintain 2 minutes and 17 seconds of hovering
power!!! Again, I define hovering power as the duration a heli can
maintain a spot over the ground at waist to chest high altitude for as
long as possible without the need for significant increases to throttle
to maintain the same altitude as when the test flight was first initiated.
Pathetic! My setup included the heavy Walkera cabin or canopy from
the "bare bones" replacement kit, GWS PG-03, HiTEC Electron 6 Ch.
receiver with a "long can" Feigao brushless tail motor, Castle Creations
Phoenix-10 ESC, GWS ICS-300 main motor ESC, stock RK-370SD with
a 10 tooth pinion, stock plastic replacement main rotor blades, HiTEC
HS-55 cyclic control servos, stock frame and rotor assembly, Direct Drive
tail with a GWS 4530 tail rotor, a Great Planes Electrify 8-cell 650 MAh
NiMH flight battery pack and various connectors, nylon zip strips, tape
foam etc... With the aforementioned setup, I right at the 2 minutes 17
seconds mark, there was a rather sudden dip in available power and then
even with full throttle stick deflection, the heli gently drifted back down to
the floor of my garage. It required 60% throttle stick deflection to maintain
a waist high hover with a freshly charged 8-cell flight pack. After this flight
as you could imagine I felt VERY disgusted with NiMH batteries and elec-
tric power in general. I didn't fly for literally 4 weeks after this and obviously,
flying was not fun anymore. I wasn't sure what I was going to do with the
helicopter as it was all I had and I did not and still do not have enough cold
hard cash to buy LiPO packs and the ESky HoneyBee 2CP kit. One day
I decided not to give up and try and work with a VERY MARGINAL, but
highly reliable setup. My idea was very simple, do NOT change a single
parameter in the helicopter's setup, except for the removal of weight out of
the heli. I removed both black plastic covers to the GWS PG-03 gyro, I
removed the top heavy blue plastic cover to the HiTEC Electon 6 channel
receiver, removed the Walkera black plastic box that comes with the original
kit to house the 4-in-1 controller PCB board, removed every last piece of tape,
foam, zip ties, rubber bands and replaced the Walkera cabin or canopy with a lighter Humming Bird cabin. Perfomed as best as I could the same test
profile as in the hovering power endurance test flight of 4 weeks prior and
was very surprised at the result; I was able to maintain hovering power for
3 minutes and 50 seconds! This was a full 1 minute and 33 second in-
crease in hovering power duration. OK I thought, we already know that
weight is your number one enemy in EPS or electric power, but I was
thinking that due to the relatively high weight of my all separates components
and a Direct Drive tail rotor setup, that I would need 60-70% throttle stick
deflections to maintain a chest high hover, minute after minute and this
was putting an unusual strain or current demand on the AAA sized cells
of the Electrify 8-cell packs. So, I was fortunate enough to have access
to a 7-cell 600AE sized 1100 MAh NiMH pack that on paper weighed in
about 1.5 ounces heavier than the Electrify 8-cell pack. My hunch for
even attempting to use this pack was that it was designed to be used
with brawny Speed 400 sized airplanes that demand sustained amperage
draws of 10 Amps. I figured due to the relative weight of the helicopter
and its two motors demanding Amps, this pack may give the necessary
punch to fly for 6 full minutes in a hover with my current setup. After the
flight pack was cycled, I was surprised to find that the helicopter was only
able to maintain hovering power for 3 minutes and 25 seconds and at the
4 minute mark always(kinda strange), the heli could not exceed neck high
altitudes while the main motor stopped turning on the ground for the very
first time at 7 minutes and 18 seconds. As a side note, with this 1100 MAh
600AE sized cells, the heli could not break the ground at the 5 minutes and
40 seconds mark. The flight pack used for the tests was from Hobby Lobby
and was an 7-Cell 1100 X-Cell Sport NiMH Pack rated to 20 Amps. These
test showed that again weight was a major issue even if I had a battery
that could really provide a relatively high discharge C. The increased MAh
of this 1100 MAh pack was mitigated by the fact of its increased weight which
required more Amps from the main motor to lift the heli which of course de-
pleted the flight pack at a faster rate etc... I need to emphasize just how hot,
no VERY HOT both the 8-cell Electrify packs AND the Feigao brushless tail
motor would get after any flight with the Feigao setup with a Direct Drive
setup. |
Thanks.
I found one for Dragon#40 and it was $15/shipped, I am wondering what other Birds are Compatable with the Dragonfly22E? Does anyone know? AS I might be best to pick one up that is just being sold for these odd "parts". . hmm, anyways, look forward to participating, and learning about my new hobby.
