Model Helicopter World USA Heli Scene April 2013

words/PICTUrEs: James Wang
USA HELI SCENE
I
n the March 2013 issue we reviewed the
Pantera P6 from Audacity Models of Florida
USA. After the review of the stock Pantera
P6, I decided to modify the model from a 50size glow engine powered helicopter to electric
using the Audacity Models Stage I Conversion
system, which cost US $99. Even though I love
flying nitro engine helicopters, I find electric
models very convenient because there is no
extra equipment to carry to the field, they are
clean in operation and there is no engine to tune.
When doing hard 3D, most electric helicopters
only have a 5 minute flight time, but if you fly in
a leisurely manner with a combination of forward
flight and mild 3D, it is possible to achieve 6 to 8
minutes.
The downside of flying electric models is one
needs at least two to three sets of battery packs
to fly back to back. Some modern LiPo batteries
can now handle 3C charge rate, in which case
it becomes possible to quick charge a depleted
battery pack in 20 minutes at the field, although
this can reduce their effective life. A set of 8
to 10s 4000 to 5000 mAh LiPo batteries can
cost $150 to $350, but if treated properly, and
provided the batteries are not damaged in
crashes, the latest LiPo packs can be recharged
at least 100 times.
The Pantera nitro P6 is very rugged, but
heavier than other 50-size nitro helicopters on
the market, so the electrified P6 could be heavier
than a 600 class model designed from the start
for electric flying. However, after converting my
Pantera P6 to electric power, the end result
shows that with a 10S LiPo it had superb flight
performance, as good as a Nitro powered P6,
with faster acceleration and more 3D punch.
With an 8S LiPo, the Pantera is smooth and
pleasant handling.
Converting AudACity Models PAnterA P6
froM nitro to eleCtriC And flybArless
James flying the Pantera P6 that
has been converted from glow
engine powered to electric powered
This is James’ Pantera P6 with
flybarless rotor, a 630 kV electric
motor, a 9-tooth pinion, and is
powered by 8S LiPo battery
Nitro to Electric Retrofit
The basic idea of the Audacity Models electric
conversion is to replace the engine, muffler,
engine mount, throttle servo, governor, fuel tank,
fuel lines and filter with an electric motor, ESC
and LiPo batteries. To achieve this they offer two
conversion packages; Stage I for $99 or Stage II
for $139.
Stage I comes with only 3 major parts and
some screws: a 4 mm 6061 T6 aluminium plate
to mount the motor, an aluminium adaptor to
mount the 10-tooth steel pinion from the original
clutch bell to the electric motor, and a plastic tray
for mounting a second 5s battery underneath the
tail boom. Using an aluminium adaptor to re-use
the 10-tooth clutch pinion is a clever way to save
money and re-use existing parts.
The Stage II Conversion has nothing to do with
Stage I Conversion as it comes with the 4 mm
aluminium motor mounting plate, rear battery
tray, and a different adaptor which permits
mounting the Pantera P6’s centrifugal clutch
to the electric motor so the motor drives the
centrifugal clutch and clutch bell.
This is an interesting solution because as you
advance the throttle stick, the electric motor has
to reach at least 2500 rpm before the centrifugal
clutch engages with the clutch bell. This system
seems safer as in the event of an inadvertent
hot start, the clutch will provide some ‘give’.
This conversion offers a unique and very scalelike spool up, which looks and sounds like a jet
turbine because the motor whines while it winds
up before engaging the clutch shoes, then slowly
begins rotating the main blades.
Go to www.audacitymodels.com and you
will see a YouTube video link of a scale electric
Agusta A-109 helicopter with Pantera P6
mechanics using Stage II conversion.
Both conversions cleverly use the original
10-tooth steel pinion and the original pinion
support ball bearing to anchor it. This support
bearing is mounted between the sideframes
preventing the pinion gear from walking away
from the main gear under heavy load and as a
result, prevents stripping the plastic main gear
even when using very high torque electric motor.
The downside of this design is you are stuck
with using the existing 10-tooth pinion. So
you have to set your rotor speed by deciding
how many LiPo cells you want to use and then
choose a motor with a kV rating that provides the
rotor speed you desire. The calculation is very
easy. For me, I decided to use my 8-cell 4270
mAh LiPo, and I want to have 1900 to 2000 rpm
rotor speed. Therefore, I chose a Hacker Turnado
A50-10L 580 kV, which with the fixed 8.7 to 1
gear ratio, the rotor speed came out to around
1900 rpm.
I liked the conversion to electric using Stage
1 Conversion package a lot and so decided
to convert my older Pantera 50 to electric by
trying the $139 Stage II kit. After having tried
both, I recommend buying the Stage II because
it is almost unique – there are very few electric
helicopters with a centrifugal clutch, but Stage I
works just fine.
Modifying Sideframes
Modify an already built and flown Pantera P6
from glow to electric power requires stripping
down the model to remove the oily engine,
muffler, engine mount, fuel tank, throttle servo
and linkage, plus any engine governor. It pays to
completely disassemble the sideframes because
they will be dirty due to exhaust oil plus dust.
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$99 Stage I Conversion set
Before converting from glow to electric power
Stock Pantera P6 moulded sideframe before modification
The arrows point to where the plastic must be removed to convert it from
engine power to electric power
The arrows show after removing the plastic
with a Dremel Moto-tool
The Dremel Moto-tool with a carbide composite
cutting wheel is a necessary tool to do the
conversion job. It is easy with this tool. Do not
use a knife because the plastic is very hard
After a cursory cleaning to knock off the
majority of the crud, Audacity recommends
running the plastic sideframes through a
dishwasher cycle and they will come out looking
brand new. Since the conversion kits do not
come with instruction manuals, the entire
procedure is detailed on their website along with
plenty of photos.
The hardest part during the conversion is to use
a Dremel Moto-tool with a composite material
cutting wheel to remove the moulded plastic
webs on the plastic frame to allow mounting of
The 4 mm aluminium motor mounting plate
is used as a jig to drill 8 holes on the plastic
cooling shroud
My Redline 53 engine in the Pantera P6 before
removal
Use a long drill bit to drill 8 holes
With the 4 mm thick aluminium motor mounting
plate trial fitted in the location above the plastic
cooling shroud for the engine
the 4 mm thick aluminium motor mounting plate.
The photos show the Pantera frames before and
after removing the plastic.
The next task is to carefully place the aluminium
motor mount where it should be located and
Looking from the bottom side of the cooling
shroud. Eight bolts are used to secure the
aluminium motor mounting plate
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drill 8 holes in the plastic cooling shroud for the
mounting bolts. Make sure the plate is placed
perfectly before drilling because once the plate is
fixed and mounted, there is no way to adjust the
gear mesh between the 10-tooth pinion and the
87-tooth main gear.
Fortunately, the aluminium plate is designed to
fit snugly, so there is not much margin for error,
but still be very careful. This is the most important
step in the whole conversion process. In the
future I hope Audacity Models will sell sideframes
prepared for electric operation, and better yet,
why not sell a complete electric Pantera P6E kit?
The Stage I Conversion includes this aluminium
‘coupler’ that permits re-using the original
10-tooth steel pinion from the Pantera clutch
bell. This is clever because the pinion is also
anchored securely above using the original
support bearing. This is why the 8 holes must
be drilled accurately to guarantee alignment
between the motor shaft and the support
bearing, and to guarantee proper gear mesh
James added a cut out on the side of the cooling
shroud to exit the motor wires. Here he is trying
a 9-tooth pinion mounted directly to the 5 mm
diameter motor shaft. This precludes using the
support bearing to anchor the motor pinion
This shows the proper gear mesh between the
87-tooth plastic main gear and the steel pinion gear
The top support bearing block removed to
show the pinion gear
Motor, ESC and Battery
Having used the stock Pantera 10-tooth pinion
with three different motors, I can say the sweet
spot for hovering is 1600 rpm and for aerobatic
in Idle-Up is 1850 to 2100 rpm. I tried a Scorpion
HKIII4035-530 motor with 10-cell LiPo: this is the
hot 3D setup for aggressive 3D flying. The main
rotor speed is 2150 rpm and it flies like a bat out
of hell 700-class electric helicopter! This setup is
for experts.
For beginners and intermediates, either the
Hacker A50-10L or Scorpion HKIII4025-550
motor with 8S 4200 to 4400 LiPo, will provide
a rotor speed around 1800 to 1900 rpm. This
combination is a sweet combination being
pleasant and powerful enough and I recommend
it for most people.
A fourth combination I tested is a Scorpion
HK4025-630 motor with an 8S LiPo and a
9-tooth pinion – I happened to have a 9-tooth
Mod 1 steel pinion gear with a 5 mm pinion hole,
which was borrowed from an old Raptor E550
kit. So I mounted it directly to the motor and this
combination provides a rotor speed of 1850 rpm.
At 1850 rpm, the electric Pantera is quieter and
less intimidating, but was still able to perform
most 3D manoeuvres and I got 7 minutes flight
time. This is the latest combination I tested and
hence most pictures show this.
10S Versus 8S
The finished electric Pantera ready for flight with 8S LiPo
The 8S LiPo fits on the front to provide perfect
C of G. The plastic frames must be modified to
fit the 8S LiPo battery
Plastic frame before removing the plastic
cooling shroud front lips
Audacity Models recommends using either
two 5S 3800 to 4400 mAh packs connected in
series to make a 10S pack and advise against
using two 5S 5000 mAh packs because they
are too heavy. When using two 5S, it is a must
to use them connected in series; one must be
strapped to the front radio tray, and the second
strapped to the extra rear plastic tray, which must
be mounted behind the sideframes under the tail
boom.
I tried it, but was worried about the moment
of inertia due to two separate packs far apart,
but after a few flights, I didn’t notice anything
unusual and soon quit thinking about it because
After removing the plastic cooling shroud front
lips to permit mounting of the 8S LiPo battery
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The electric motor fits perfectly in the original
circular hole in the middle of the cooling fan shroud
The 8S 4270 mAh LiPo battery fits perfectly
between the sideframes
Use at least two Velcro straps to secure the flight
battery so the battery cannot move during 3D
4 mm thick, single-sided sticky foam added
to prevent the LiPo flight battery from shifting
during flight
The field programming box and USB adaptor
for programming the ProModeler electronic
speed controller (ESC)
the model flies just like an ordinary Pantera P6.
An advantage of using two 5S pack is if one
pack puffs, or goes bad, then you can replace it
for half the cost of a single 10S pack (although
the replacement pack must have the same
performance as the older one).
In the event of a crash, if you ‘taco’ the forward
pack, it’s the half price to replace because the aft
pack is protected within the frames. If you prefer
Top of the 100 amps ProModeler ESC shows
the aluminium construction with built-in heat
sink for cooling
The 80 amps ESC from www.promodeler.com is
only $69. It is only good for up to 6S LiPo, but has
a built-in 4 amps BEC. This is a great bargain
The 100 amps high voltage ESC from
ProModeler used for the Pantera P6. It does
not include a built-in BEC because it is a high
voltage ESC that can handle up to 12s LiPo,
hence it uses an opto-coupler. February 2013
USA Heli Scene column explains what is an
Opto-coupled ESC
a single 10S pack, Audacity Models offers an
optional carbon fibre battery support that mounts
between the frames and the landing gear struts.
For me, I like the 8S power option because it
is easier to use a single 8S LiPo pack strapped
under the front radio tray. I had to use the Dremel
Moto-tool to remove the front cover of the plastic
cooling shroud to allow the battery to slide back
The electrified Pantera P6 becomes a
rugged 600 class electric helicopter
This is a 200 amp ProModeler ESC for 700-800
class electric helicopters that use 12S LiPo.
Notice five capacitors are used. This rugged
ESC is 4 inches long
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The stock flybar rotor head has an angled flybar
control arm to permit maximum paddle angle
change without bumping the blade grips
Converted flybarless rotor head utilizing the
stock Bell-Hiller mixing arms to help reduce
control sensitivity – clever idea
further to get a perfect C of G balance
for the helicopter.
The reason I prefer the single 8S to the
2 5S is: 1) it puts the two battery packs far
apart and that increases the longitudinal
rotation inertia, 2) it is unnoticeable, and 3)
most reasonably priced chargers can only
charge and balance up to 8S LiPo battery
packs. I am using the ThunderPower
TP820CD charger and it can charge
two 8S packs at the same time. So it is
more convenient for me to run 8S instead Very well made 4-bladed rigid rotor head
of 10S. The performance on 8S is very
good and the flight time is 6 to 8 minutes,
actually delivering in the way of
depending on flying style and rotor speed. 10S
performance during flight. The
will give similar flight time, but will provide a more
ProModeler ESC has 256 MB of
powerful and spirited flight.
built-in memory so you can think
I tried a Jeti 77 amp ESC first and then
of it as a black box flight data recorder recording
switched to a ProModeler 100 amp High Voltage
current, voltage, temperature, throttle, time and
ESC because I want to make sure the model can
rpm.
handle 3D even in hot weather. The ProModeler
This data can be downloaded to your computer
100A High Voltage ESC (available from www.
via a special USB adapter. The software also
audacitymodels.com or www.promodeler.com)
allows you to program the usual ESC parameters
is a new ESC that features data logging so
such as soft start, governor mode, motor timing,
one can learn what the motor/ESC combo is
etc. I am very impressed with this ESC and the
price is quite amazing at only $120
for the 100 amps unit. I will describe
it more in the future.
Flybarless Conversion
In October 2008 MHW, I showed
how I converted my nitro Pantera
50 to flybarless by eliminating
the flybar and using the pushrod
to connect the main rotor blade
pitch control arms directly to the
swashplate. That worked ok, but
Parts for the $200 4-bladed rigid rotor head
Closeup of the
machined
aluminium
rotor hub
The blade follower and control throw reduction
mixing arm assembly for the 4-bladed rotor
The steel spindle and the centre hub for the
4-bladed rotor
In 2008, James tried this flybarless conversion
that gave overly sensitive pitch control; the
Audacity method is better
Pantera with the
optional 4-bladed
rigid rotor head
with four 600 to
620 mm blades
not great because the blade pitch arm is too
close to the spindle and that made blade pitch
control too sensitive.
You may have noticed that most flybarless rotor
heads on the market have the blade pitch control
arm located further away from the spindle. While
studying the Audacity Models website, it showed
how to remove the flybar and then recycle the
Bell-Hiller mixing arm as a lever arm to reduce
the blade pitch control sensitivity by 50%, which
recovers the control resolution. The picture
shows how this is cleverly done.
After converting the Pantera P6 to flybarless
and electric, it took on a whole new life. Modern
electronics SAS makes flybarless helicopters
manageable and very neutral in handling, such
that a flybarless helicopter will always try to
maintain the attitude that the pilot has demanded.
If the model was left in a 30º bank, it will remain in
that bank angle until the helicopter crashes.
By converting from flybar to flybarless with a
SAS, the transmitter cyclic sticks change from
a ‘rate command’ system to a ‘rate-attitude
command’ system. For experienced pilots, this
is actually fantastic because the helicopter does
precisely what is commanded, with no question
asked. When the pilot quickly moves the cyclic
stick right a quarter of an inch, the flybarless
helicopter will instantly roll right for example
50º. If the pilot moves the cyclic stick right half
of an inch, the flybarless helicopter will roll, for
example, 100º. As the pilot quickly brings the
cyclic stick back to centre, the flybarless model
should eventually return to level, how quickly this
happens depends on the SAS and may require a
correcting input to level the model.
The ultimate cool trend in flybarless flying is
using a 3 or 4-blade rigid rotor for 3D or scale
flying. The reigning World F3C Champion,
Hiroto Ito, demonstrated 3D with his JR NEX8
with a 3-bladed rotor with 600 mm blades at
the 2012 and 2013 IRCHA Jamboree. TSA
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In the electric
and flybarless
format, it is
very quiet and
aerobatic
The P6 uses 600 to 620 mm
rotor blades and is a stable
600-size electric helicopter
also demonstrated this and will release 3 and a
4-blade rigid rotor heads for 3D.
Audacity Models has introduced a rigid 4-blade
rotor hub for its Pantera. I just started trying one
with four 620 mm SpinBlades carbon blades; it is
fun and offers a different feel to a 2-blade flybarless
rotor. As there is more blade area, the collective
is more powerful, autorotation performance is
excellent, and hover and forward flight stability is
better due to greater gyroscopic stability.
Flying Electric P6
This is where it all comes together. With a
powerful, large bore 50-class engine, such
as the OS 55, YS 56, Thunder Tiger Redline
56 or Novarossi 57, the nitro engine version
P6 can easily perform Tick-Tocks, Chaos and
Hurricanes, etc. After the electric conversion, the
Pantera can still do all this equally well, but it’s
quieter and with no smoke.
Which do I prefer? I’m very used to flying the
nitro version and because I have flown 50-size
nitro engine heli’s for many years, tuning engines
has become second nature. Nitro engines offer
reliable performance, with quick refuelling so you
can keep flying almost continuously. Plus I love
the sound and smell of the glow fuel. However,
lately electric models have spoilt me because
there is no mess to clean up!
Ultimately, flight performance is determined by
the battery, motor and ESC combination. The
flight performance with 10S LiPo is neck-andneck with the nitro version at 2000 rpm. Using an
8S LiPo setup, the P6 is very pleasant to fly and
flight time is good because the main rotor only
turns at 1850 rpm in Idle-Up mode. With an 8S
in Normal Throttle Mode, where the ESC is set at
70%, the rotor speed is only 1600 rpm, which is
perfect for novice pilots learning to hover, or just
general flying around.
With either the nitro or electric version, you will
find the Pantera P6 very tough and ready to take
the abuse of daily flying. The mainframe assembly
is probably too rugged; I don’t think many people
will ever break the polymer sideframes.
For beginners, the milk bottle material plastic
canopy is wonderful because it is nearly
indestructible, but for years I have asked
Audacity Models to offer optional painted
fibreglass canopies. Finally, they are offering three
different pre-painted canopies and the price is
quite reasonable at only $59 each.
For customers living outside the USA, Audacity
models and parts are distributed directly
to consumers using either website (www.
audacitymodels.com or www.promodeler.com)
or via phone and Email, which often results in
you communicating direct with John Beech, the
owner and chief designer. This is a refreshing
change, because one does not normally talk
to the owner or designer when buying a mass
produced model. Hopefully, John will soon start
offering a complete electric Pantera kit. MHW
Two nitro Panteras with
the optional, pre-painted
$59 fibreglass canopies
This is the Pantera P6 glow engine model
reviewed in the March 2013 issue of MHW
When using the optional fibreglass canopy, it is
necessary to make a cut on the top lip to clear
the pushrods for the swashplate control
It is also necessary to add a spacer to extend
the four canopy mounting posts further out
Third colour scheme
Use a Dremel Moto-tool to reduce the length of
the steel sleeve for the pivot by about .001 to .002
inch to eliminate in-and-out play in the mixing arm
Optional servo output shaft anchoring system
– you must order the right set to match your
servo output shaft
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