Product Review

Product Review
Product Review
Precision Aerobatics
35% Extra 330L ARF
Anthony Demarco.
Over the past 20 years I have been involved in many aspects of our hobby. I
have flown everything from control line
models (and got very dizzy), to helicopters,
gliders, sports models, scale models, 3D
models, competed in pattern competitions
and I am now competing in IMAC in the
Unlimited class. So I guess what I am
trying to point out is that I have a pretty
good knowledge about our aero modelling
hobby……ahh sport…..addiction?!
With the current generation of ARF
kits on the market, the art of building a kit
or even scratch building a masterpiece is
slowly disappearing. I have scratch built
my own and others designs, I have built
kits and I am not afraid to say I hated it
and I have never been good at it. Thanks to
Pilot Ez (I think they were the maker of the
first ARFs??) for starting the stampede of
ARF kits to save modellers like me.
I bought my first ARF kit in 1987 (a little
electric called a ‘Snark’...No lipos…no
brushless…no speed control…no fun!!!)
and I have built many ARF kits since.
Many of the sport ARF kits serve a
purpose for most modellers but now that I
am flying IMAC, the smaller cheaper ARFs
just don’t tickle my fancy. Yep, I may
be an aero modelling snob, but I am not
interested in building or flying a model that
doesn’t fly straight and doesn’t pull like a
freight train.
The PA330L
I have always liked the colour scheme
on the Precision Aerobatics 35% Extra
330L (PA330L), the yellow, black, grey
and white colouring will be easy to see
on both sunny and cloudy days. That big
‘Precisions Aerobatics’ on the bottom of
the wing looks great too. The PA330L
is a large model with a 2700mm (106”)
wingspan and a length of 2500mm (98.5”)
and is estimated to weigh 11.5kg (25lbs).
The size, light weight and wing loading
makes the PA330L a potentially perfect 3D
airframe so I jumped at the chance to build
and review one of these kits.
Right from the start the guys at Precision Aerobatics were helpful, friendly and
efficient, these guys aim to please. I spoke
to Shaun and Adad about getting one of
the PA330L’s and with a blink of an eye, I
had three big boxes delivered to my door.
Opening the boxes revealed one of the
highest quality ARF’s on the market. The
The Stig.
covering unlike other ARF kits was done
correctly having the covering seams in
the airflow direction with a 8mm overlap
of colours, usually you will only find this
on professionally custom or owner built
models…..very impressive!
Mine came with the optional hardware
kit, carbon wing and stab tubes, wing bags
and helmet head pilot. The optional hardware kit comes with every item you will
need to complete the model. It comes with
a 32 ounce Dubro tank, petrol safe fuel
line, T piece and fittings. The hardware kit
includes beautifully made carbon fibre dual
control horns for the elevator, rudder and
ailerons. Also supplied in the hardware kit
are nuts, bolts, pushrods and main wheels
to complete the model etc and there is no
going to the hobby shop for any edditional
bits and pieces.
I decided that I wanted to build the
model as light as possible and the use of
the optional carbon stab and wing tubes
will lighten the overall weight of the model. For the guys who do not want to spend
the extra money and are not worried about
a couple of hundred grams here and there,
the standard wing and stab tubes are made
from quality aluminium although at the
moment there is a special on the Extra and
you get free carbon wing and stab tubes
when buying an engine with the plane.
The wing, stab and rudder carry bags
are custom made for the plane out of a
padded waterproof canvas and are lined to
keep your model in perfect condition ….
These are beautifully made and are good
enough to wear yourself, they even have
handles!!! My wife thinks the wing bags
are the best part of the whole model……
maybe I can sew them together and make
myself a Precision Aerobatics jacket?!?!
The helmet pilot is moulded out of
fibreglass and is extremely lightweight.
The helmet pilot can be supplied as painted
or standard white, for the artists among us.
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product review: precision aerobatics 35% extra 330L arf
Ready for the gear
It is secured with the use of the supplied
mounting plate which was simply screwed
to the canopy floor.
Let’s face it, it’s not like us blokes to
read a manual and I have built enough
models to know what I am doing, but there
is a well detailed manual that is certainly
worth reading. Some of the building tips
that are highlighted in the manual make
you ask yourself ‘why didn’t I think of
that?’ This manual was written in Australia
and the pictures are of Shaun’s actual
PA330L. I suggest you follow the manual
which will result in a well built plane.
free gear train and high torque is needed
for the 45deg deflection of the large control
surfaces used in 3D flying. These servos
will be guided with the use of my Futaba
9ZAP WC2 and DP149 PCM receiver.
In addition to the radio set up I am using
an Emcotec 5 mini power distribution unit.
The Emcotec Unit distributes 5 channels of
your receiver to eight servos. This supplies
each servo with constant current which is
selectable from 5 to 5.9v. The power to the
unit is supplied by two Precision Aerobatics 7.4v 2200mah Lithium Polymer batteries. The Emcotec unit is a simple setup
that will supply your servos with constant
current needed for all your 3D and IMAC
demands. They even supply a stand off
vibration mounting system for the Emcotec
unit. This mounting system will supply the
unit with the adequate ventilation necessary
for the required heat distribution. It is this
impressive attention to detail that sets this
model and Precision Aerobatics apart from
their competition.
The final step is to mount the motor,
canisters and fuel tanks. I have chosen a
DA100 and BMB 60XL canisters from
Desert Aircraft. The DA100 is a 100cc twin
engine made in good old US of A. The motor weighs 2600g and puts out just under
10 horse power. I want to get the PA330L
down on the deck so I want power and reliability. The last thing I want is to have the
motor quit when I don’t have the airspace
to recover. You can get Desert Aircraft
motors from the same place you buy this
plane. I decided to use canisters because
of the need to quiet my engine down due
to noise restrictions at my local field and
I will also benefit from an increase in performance. The BMB 60XL canisters were
also chosen because they are only 60mm in
diameter and the opening for the canister
tunnel was a total of 130mm.
Mounting the engine was extremely easy
with the help of ply laser cut standoffs.
Connecting the throttle to the throttle servo
I started building the model by putting on
the landing gear, wheels and wheel spats.
This is an easy task and gets the model
off the ground. Isn’t it funny how putting
the landing gear on a model makes it look
almost built?! The next step was to glue in
the Robart style hinges and seal the gaps
with the supplied covering. For a guy who
hates building, so far this wasn’t too bad.
The canopy comes already tinted with
the yellow painted around the outside. Not
much to do on the canopy except glue it
on. I gave the inside of the canopy and
the covering a quick scratch up with some
sandpaper and glued it on with canopy
glue. Before you glue the canopy on make
sure your pilot is firmly in place. I used the
supplied mounting frame and some screws
to hold down ‘the Stig’. I assembled the
model and found that the overall fit of the
wings, stab and canopy frame was perfect.
Did I mention the size of the model is
impressive too.
The installation of the radio gear was
straight forward with two servos used
in each wing panel, one servo on each
elevator and two servos on the rudder. I
am using Hitec 5955TG servos with 24kgs
of torque. These servos are bigger than
needed for IMAC style flying, but the slop
Twin cylinder
Desert Aircraft DA
100cc engine
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product review: precision aerobatics 35% extra 330L arf
was also easy using the supplied carbon
pushrod, I simply glued a ball link on either end of the push rod and connected it to
my servo and throttle. It doesn’t get much
easier than that. Mounting the canisters
proved to be a little more difficult as the
room inside was getting a little cramped.
A additional tank tray designed to raise the
tank above the canisters was supplied and I
cut out the existing tank tray and made up a
former out of light ply to hold the canisters
in place.
I also was supplied a header kit to make
up custom headers to fit the PA330L. With
some cutting and silver soldering by Chris
Swain, the headers were a perfect fit. Final
mounting of the motor was done using
6mm steel bolts and blind nuts, I then put
nylon lock nuts behind the blind nuts to
stop any possible chance of the bolts coming loose. To complete my engine package
I am using a Precision Aerobatics 4.5in
carbon spinner and a 28/10 Mejzlik prop.
I should probably add that at this stage
I decided to reinforce the fire-wall. Shaun
does recommend that you fibreglass the
outside of the firewall to reinforce it. I
went one step further and used two 100mm
light aluminium angle and bolted it to both
sides and front of the engine box. That ain’t
going anywhere! To mount the cowl I followed the instructions and glued in the ply
retaining ring, this enables you to attach
the cowl with bolts into blind nuts which
are accessed through the canopy hatch. The
ring is reinforced with the use of fibreglass
cloth. There is a bit of fiddling to do here,
but the result is worth it.
It is an Australian Scale Aerobatics
A header kit for this
engine combination
is available. BmMB
60 XL canisters
really pull the noise
level down and
increase the power.
Association (ASAA) requirement that all
scale aerobatic aircraft participating in
Australian IMAC competition must have
a second means of engine kill via the
transmitter. This requirement is obviously
directed towards petrol motors. Options
for second engine kill are servo operated
choke (a servo cut out is provided for by
Precision Aerobatics) or an ignition kill
switch. I chose to use a Smart Fly Optical
kill switch, which can also be purchased
from P.A This kill switch goes between
the battery and ignition and is operated by
a spare channel on your radio. I then dry
assembled the model to check the centre of
Because I used canisters I expected the
model to be nose heavy, with careful placement of the radio gear inside the model I
found the centre of gravity balanced according to the recommendations. The balance point was at 220mm from the leading
edge measured at the root rib.
My radio set up is very close to that recommended in the instructions. I have the
model set up with high rates for 3D flying
and low rates for IMAC flying. Those big
PA carbon fibre servo arms are giving me
huge deflections. It had only taken 4 good
days in the workshop to have the PA330L
ready for flying. I guess the crappy weather
was good for something.
Finally the test flight day was here, and
the weatherman proved to be right for a
change, the predicted gale forced winds
were still here…..bugger!
The Precision Aerobatics twin servo
rudder pull pull system.
Number 83 April-May 07
The next day (a Monday of course) the
winds were gone and the sky was blue.
Work is a dirty words on days like this, so
I went flying. A couple of phone calls and
a bunch of mates were at the field to lend a
hand. A couple of photos were taken and it
was off to the flight line to start the DA100
up and shove the PA330L in the air. The
brand new engine started for me like we
had known each other for years. I ran the
motor to check its tune. Sounds good to
The Extra was pointed into the wind, I
opened the tap on the big engine DA100
and it flies. I left the climb out on a shallow
angle for about five seconds, reduced the
throttle and started to do a rolling circle to
turn the model 180 deg. Not bad. The rest
of the first flight consisted of vertical up
lines, down lines, rolls, snaps, spins, point
rolls, inverted flight, knife edge, a so so
rolling harrier, flat spins, the most awesome
water fall you have ever seen, a blender, a
bit of hovering and a wall.
Flight breakdown
On to the important stuff, the flying. I have
broken down the first couple of flights into
the individual manoeuvres I did in more
detail. The PA330L is easy to fly through
any 3D manoeuvres and is graceful and
forgiving. Kind of like a big 3D trainer.
The model was controllable in the Roller,
but with deflections recommend for low
rates and the rearward CG, it was way too
twitchy. That is not to say the roller was
hard to do, but took a bit more concentration. Getting used to the model would help
a lot too. The vertical performance with
the DA100 was unbelievable. I have flown
many 50cc, 100cc and 150cc sized planes
and the power in this light airframe is awesome. Love me D.A. The up lines require a
bit of right rudder and the down lines need
a bit of down elevator. This is easily mixed
in your computer radio.
The rolls and point rolls were very good,
but the model does need a hint of differential for the model to roll axial. An eight
point roll from one end of the sky to the
other was not a problem, but could be made
easier with a bit of mixing. Snaps start and
stop, now! Light wings are the go. Doing
multiple snaps in the upline was very easy
and unloading the snap helped a lot to keep
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product review: precision aerobatics 35% extra 330L arf
the model on track. Spins are nice and easy
but I did find they are a little hard to do in
the wind. The PA330L just floats and floats
The model just seems to lock in while
in inverted flight. Cruising across the sky
inverted, the model just sits there making
the pilot look good. The recommended
CG will make the PA330L fly an inverted
45deg up line without any down elevator.
Knife edge flight is very easy and applying
full rudder will just make the model climb
into a knife edge loop. A tiny bit of up elevator needed to maintain heading, but that
is easily mixed into your computer radio.
High alpha knife edges down the runway
are sweet.
The rolling harriers were a bit high and
the timing was wrong on the first flight. A
couple of flights later had me easily doing
rolling harriers across the sky. I think the
PA330L made it look like I can do rolling
harriers ?
Flat spins are flat as a tack. I had to
release some of the elevator to stop the
model from wanting to go back up. Not
really much to do except watch. The model
stopped the instant I let go of the sticks.
Imagine putting a rod through the wing tip
and out the other wing tip, get two people
to hold on to the rod while the model is
spinning end over end. I don’t think the
model lost any height during 4-5 rotations.
That is the Waterfall and Blender. The
blender wasn’t violent at all and easy to
do. There is something about blenders that
make the crowd go….ooohhhh
My mates in the back ground were my
good conscience on this one. I started to
hover the model and in the background
I hear “It is a new motor!!!”……yeh
your right….damn it! Later flights had
the PA330L hovering with ease. There is
How that for a flat
spin. Now that’s flat.
heaps of power with the DA100 to pull the
PA330L out of the hover. Torque rolling
is very easy to maintain and hold. As for
the Wall, I just did tell them I was going
to do one, bam! The big Extra stopped all
forward speed and hung there, cool. There
was no sign of rolling off to one side or the
other, it was like it hit a ‘wall’.
The model also does the coolest Knife edge
spin, often call the Hanno Screw. It will fall
on one wing tip and stop the instant you let
go of the sticks.
With these settings my PA330L flies hands
off in an upline and downlines plus knife
edge flight.
7% up elevator with rudder application;
2% down elevator at low throttle;
A hair of right rudder with full throttle; and
60% expo on all surfaces.
To give you an idea on how easy it is to fly,
I gave my brother, who hasn’t learnt to land
yet, a fly. He did he’s first positive snap roll
with the PA330L. A couple of others from
3 to 20 years experience got to steer the
PA330L around the sky. All agreed that it
was easy and great to fly.
Hits and misses
Hits: Well thought out design. Excellent
covering application. Light and straight
airframe. Easy to see in the air. Great 3D
Misses: Covering gets wrinkled very
quickly. Nothing an iron won’t fix. Canister
tunnel is too small.
Like I said in the beginning, I am not a
builder and do not really enjoy it. I didn’t
mind building the PA330L because everything fits and the supplied hardware was
picked for a reason. There were no major
problems and I would think anyone with
a couple of ARFs under their belt could
build one easily. I would recommend that a
novice get help from an experienced giant
scale modeller just to point out the do’s and
If you are considering getting into a 35%
aerobatic model that will do every 3D manoeuvre you can think of, I can recommend
the Precision Aerobatics Extra 330LL. PA
website ( features
about 4 videos showing different set ups
and different flyers (including myself) and
I recommend watching!
Hovering, seems
like just above idle.
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