- Q
- Can I use a transmitter without CCPM mixing on a
LOGO electric heli?
- A
- The LOGO 16 uses mechanical mixing as did the
original LOGO 20. With only a few extra parts, the
current LOGO 20 can also be setup with mechanical
mixing
-
Q
- How do you check your receiver battery?. What
should the voltage read? Seems like when it gets close
to 5 volts that's when the heli stops abruptly.
- A
- Yikes! You need an ESV, which is an Expanded Scale
Voltmeter that measures your batteries under load. It
has two inputs and scales - one for the Rx battery and
another for the Tx battery. Very important! heli's
suck receiver batteries dry because of the high loads
and constant operation of the gyro and tail rotor
servo. More with digital servos. You can get one at
any R/C hobby shop.
-
Q
- How do I range check my eloectric heli?
- A
- In addition to following the radio manufacturers'
directions, one should weigh down the heli with a
heavy bar across the landing skids or a similar
arrangement. Do a range check with the motor off
(watch it -I've had the motor kick on during one of
these) and then another one with the motor running low
rpm and neutral or negative pitch. Moving the tail
rotor blades away from their proper position makes
their movement easy to see at a distance (for the
static test). The LOGO's antenna position low on the
landing bows tends to give poor ground range unless
the heli is raised a little. The point in the range
check is to detect a change in otherwise consistent
results.
-
Q
- My only concern with the LOGO 20 is the loose gear
mesh between the tail rotor drive gear and the spur
gear. It seemed too loose to me while I was building,
but there is no adjustment available. There was a
substantial amount of white plastic shavings from the
spur gear in the motor and servo areas after the first
two flights and I think it was caused my this loose
gear mesh. I have the motor pinion mesh set pretty
well I think - it is close, but there is some gear
lash in all positions. Should I be concerned, or is
this "normal"?
- A
- The tail rotor gear mesh will be fine as it is. I
would not worry about the plastic shavings. This is
from the power absorbed from the pinion gear and it
should reduce after a few flights. My first main gear
lasted for hundreds flights, although there was a
noticeable scallop worn into the gear teeth.
-
Q
- When I built the heli, I did not add lubrication
to the bearings or the one-way hub. I only greased the
thrust bearing. Is this correct?
- A
- That`s okay. You can apply lubricant later when
you do a maintenance session. I use a product called
"The
Greaser".
-
Q
- Do I need to lubricate the bearings on my
motor?
- A
- That is a tough question, especially when one
wants to protect the motor after exposure to moisture.
Advice is often given to periodically add a few drops
of oil. However Mike from Kontronik advises not to do
this because it would rinse away the original grease.
I also worry about mixing different lubricants. My
strategy is to periodically examine the feel of the
bearings and once some wear is detected the bearings
are removed and re-greased with "the greaser" at the
same time new bearings are ordered while dimensions
can be measured.
-
Q
- Should I use a fuse?
- A
- No, because of the high peak currents that can be
drawn and the consequences of loosing power at the
wrong time.
-
Q
- How do I estimate maximum rpm for my setup?
- A
- What works for me is to use a voltage of 1.05 per
cell, which accounts for the cells' drop in voltage
under load and other small factors. Motors have a "KV"
rating which is stated in rpm/volt - they will turn a
more or less fixed rpm for each volt applied.
So....
- Rotor RPM = voltage x KV x gear ratio = 1.05 x
# cells x KV x pinion teeth/spur gear teeth
- As an example, using my LOGO 10 setup with the FUN
600-18 ("18" stands for 1800 rpm/volt), 13 cells, 14T
pinion, 200T main gear:
- Rotor RPM = 1.05 V/cell x 13 cells x 1800
rpm/volt x 14T/200T = 1720
- In the recent past, I used a 15T pinion, which
gave:
- Rotor RPM = 1.05 V/cell x 13 cells x 1800
rpm/volt x 15T/200T = 1843
- ...and I was flying it at about 1800 rpm. I am
experimenting with lower head speeds and a 14T pinion
at the moment.
-
- Dana Ferguson (aka Lost Horizon) has contributed a
link to his rpm
calculator, which does the same thing! Also Danal
Estes has made this Excel spreadsheet.
Q
- How do I measure the actual head speed?
- A
- While there are tachs available that strap to the
tail boom and have a large LCD readout, I think that
the MA (Miniature Aircraft) optical tach is better. It
can take readings from a distance during aerobatic
maneuvers, which I find interesting, if not
useful.
Q
- How do I keep an electric heli from crashing when
the batteries run out?
- A
- Since one always starts a flight with a fully and
recently charged battery and since their performance
is very predictable, a timer (built in Tx or external)
is used to warn one as the batteries are almost
drained. One gets to know the timing involved and be
ready to land. I usually do some hovering/orientation
maneuvers during the last 15-30 seconds of the flight
so as to be close to the landing pad.
-
Q
- What is the best route for the LOGO 20 antenna?
I've read somewhere that it should go out the front of
the canopy and hang down before being routed back
though the usual hollow tube. Is this the best as it
seems as though it would be a pain to take the canopy
off.
- A
- Yes, this is a tough one. I didn't want to follow
the instuctions either :) When Ralf from Mikado saw
how I'd run my antenna, he was shocked that I was not
geting "interferences". I loop it behind the fron
landing gear cross member and then out front to enter
the antenna tube. It passes a little close to the
motor. The only reason that I have not changed it is
because it works, but here's what I think is the best
way... Get a Revolution whip antenna and mount it on
the side of the servo tray or at the nose, so that it
points forward - right through a hole cut in the nose
of the canopy. I've heard of this being done and
working quite well and again, what I would do
-
Q
- Do I need to purchase upgrades with my new Mikado
LOGO heli?
- A
- Generally, no. However the LOGO 10 does require
the thrust bearing upgrade for high performance flight
over 1600 rpm.
|
|
- Q
- Do I need to use F/G or C/F rotor blades on my
LOGO 10?
- A
- Although the Mikado 500 mm F/G blades give
slightly longer and smoother flight, they really
aren't needed until high performance aerobatics are
learned. They will work OK for loops, rolls, etc. and
help keep down expenses during the learning
phase.
-
Q
- Can I repair a damaged rotor blade?
- A
- No
-
-
Q
- What field equipment do I need?
- A
- For starters, a battery charger, charging battery,
ESV (look here), Hex wrenches,
particularly 2.5 mm, Tri-Flow oil (works well on T/R
shaft ad sliders on main shaft, but NOT BEARINGS),
sunglasses. Nice to have items include a separate
small peak charger for the transmitter and receiver
batteries, if one is not provided on the charger
(Schulze chargers have this feature), a cooling tube,
and a folding table.
-
Q
- I hear recommendations for expensive chargers, but
there's full-featured ones available for much less
money that charge at 5 amps. Do I really need to
invest in a premium charger?
- A
- NiCads used in our heli's work best when charged
at at least 6 amps. The cheaper chargers would
otherwise be fine, except for the fact that they
cannot charge at their maximum rate with larger packs.
My Orbit Microlader Pro puts up to 7.5 amps in my 24
cell packs, for instance. The factor that "separates
the men from the boys", so to speak, is WATTS, not
maximum amps listed.
-
Q
- My flight packs have been unused for several weeks
so should I treat them in a special way for the first
charge?
- A
- That's a pretty short time and I wouldn't worry
about it.
-
Q
- What is a cooling tube and do I need one?
- A
- A cooling tube is basically a piece of pipe with a
computer fan on the end to draw a small stream of
fresh air over the pack. It is amazing how well this
cools down a pack, even better than sticking it in a
freezer. The hotter the ambient temperatures, the more
valuable it is.
-
Q
- When do you need to cool the batteries, after
flying before charging or after charging before
flying?
- A
- After flying. You can fly them "toasty" off the
charger.
-
Q
- Do I need to get a "hump" pack if I use 13 or 14
cells in my LOGO 10?
- A
- No, but one thing that you might have to do (per
manual) is put a small ply spacer at the very front of
the battery tray to lift the front of the pack (and
C/F brace if used) up a bit. I used servo tape to hold
it in place. Currently I am copying Ralf and putting a
good wrap of tape around the middle of the pack where
it overhangs the edge of the battery tray to help
brace the pack and hold it more suggly against the
inner plywood keel of the pack when the shrink softens
during flight. This also serves to lift the 13 cell
pack enough that the ply spacer is not needed. Also,
if a UBEC (I like mine!) is used, there is less weight
in the receiver & rx battery tray at the rear, so
the flight battery does not have to stick out as far
to balance the heli.
-
Q
- I have a Shultze Future 45Ho ESC and was wondering
how it is setup for governor mode. Is there a mode in
the ESC or is it just how it's setup in the throttle
curve (as explained on your site).
- A
- (edited to fix small error)
The governor mode is engaged when the speed
control is powered up with the throttle channel above
"idle". Depending on how far above idle, one of two
modes is selected based on the type of motor used.The
transmitter setup you
refer to is a seperate, necessary matter for proper
operation of the
speed control. The
initialization
described below is pretty easy once you get the hang
of it, and you do it every time you powerup the heli.
Since you very likely have a Hacker or Kontronik motor
on your LOGO 10, you want to select the so-called low
rpm mode governor mode (per the Speed regulator mode
section of the manual) for these 2-pole motors. To do
this you have the throttle between idle and mid-stick
(50% throttle or less) when you plug in the flight
pack. When you first plug in the flight pack, the ESC
"beeps" the motor twice to indicate which
frequency/timing mode has been
programmed
in a one-time operation (in my case it's 2 beeps)
as per "set operating modes" section of the manual.
Then after a couple of seconds it beeps twice again to
indicate that the "low rpm mode" has been chosen as
described above. Then you must bring throttle to zero
to finish and the motor beeps back at you with one
beep to indicate that it is now armed.
In summary (for Kontronk/Hacker motors):
- throttle a bit below 50 %
- plug in battery
- 2 beeps
- wait
- 2 beeps
- chop throttle
- one beep
- ARMED (go fly)
-
Q
- Does this controller (applies to several brands)
have constant speed (governor) capability that I could
use from a rotary control on my transmitter, and if so
how does it work?
- A
- Yes it does have a governor mode. I explain how to
setup the transmitter elsewhere on this website. There
are two ways to control the throttle:
- with an auxilliary channel controlled by a
knob. No pitch/throttle curves are required, but
there must be a means of assigning a channel to a
rotory knob in your transmitter's software)
- via the throttle channel by setting up
pitch/throttle curves per the procedure here.
-
Q
- Can I just run the ESC on my electric heli from my
throttle channel like a glow ship?
- A
- You could do this, but in general the governor
mode works better.
-
Q
- I am seeking advise on the use of governers on an
electric heli. It is a new concept to me. On my glow
powered helicopters I had everything mechanically
synchronized. The throttle was synchronized with the
pitch.
- A
- In governor mode, the speed control does all the
work. Normally, as you know, a certain throttle
position will not give connstant rpm - as load is
added, the rpm drops. Just think of the speed
control's governor mode in the simplest terms - it's a
rpm setting:
- normal mode: % throttle channel = throttle
setting
- governor mode: % throttle channel = rpm
setting
Another way to look at it is to think about how an
automobile's cruise control works a lot better than
just holding the gas pedal in a certain position:) The
rpm is not pegged in any linear way to the setting,
it's just all relative. IOW, 85% throttle does not
give 85% of full throttle rpm. Provided that you setup
the throttle so that it is normally at something less
than full throttle, say around 85%, the governor will
have some power to spare to use when regulating rpm.
When load is applied, the ESC can just "step on the
gas" automatically to keep the rpm more or less
constant.
|
