Radio Controlled Model Helicopters FAQ
The following are the most commonly asked questions and
their answers about model helicopters.
Where did it all begin?
Helicopters are fascinating
machines. In the full size world, it wasn't until well after fixed winged
flight had been mastered that Igor Sikorski in the late 1930's unlocked
the secrets of controllable helicopter flight.
Even though model aircraft
have been around as long as their Full size counterparts, viable model
helicopters remained elusive. For a whole lot of complex technical reasons,
copying the full size just did not work! It wasn't until the late 1960's
that, due to the persistent and laborious efforts of Dieter Schluter that
a model helicopter first flew and was capable of controllable flight. The
secret, in part, was the addition of a fly bar to the rotor head. This
is the extra bar and 'paddles' that are located 90° to the main rotor
blades.
What sizes do model helicopters come in?
Generally, model helicopters
come in either 30 or 60 size. This refers to the capacity of the engine
and reflects the size of the model. A 30-size helicopter has an engine
capacity of .30 cubic inches or 5cc. Has a rotor diameter of approximately
1.2 metres and weighs about 2.5kg. A 60-size model has a rotor diameter
of about 1.4m and weighs about 5.5kg. The engine being .60 cubic inches
or 10cc in capacity.
What types of Models are there?
Undoubtedly, the most impressive
helicopter is the Scale model. As this implies it is one that has been
modelled on the Full size equivalent. These look their best when flown
like the Full size, although some models are capable of aerobatics.
Mostly people start out with
'Pod and Boom' (open structure type helicopters). The advantage of these
is that the mechanics are accessible for easy maintenance and are much
easier to repair in the event of a mishap Some 'Pod and Boom' models in
the hands of skilled pilots, have the potential to perform spectacular
aerobatics.
What type of engine powers the models?
The capacity as mentioned above
is usually 30 or 60 size Similar to fixed winged models, the majority of
model helicopters are powered by two stroke glow plug motors. However model
helicopter engines are slightly different to the model aeroplane equivalent,
in that the cylinder head has a larger heat sink or cooling fins and modified
carburettor to give accurate throttle control at 50% power, the setting
at which most flying is performed.
Typical engines are 32SXH (30
size) and 60SXH (60 size). The 'H' indicates it is designed for helicopter
use. The engines usually have a ball raced crankshaft and piston ring
(this is not common with aeroplane engines). The power developed is about
1.2 horsepower for the 30 size and 2.2 horsepower for the 60 size at about
17,000 rpm
What fuel is used in model helicopter engines?
The most common fuel for glow
plug helicopter engines is a mixture of methanol, nitromethane and oil.
Modern fuels tend to use a synthetic oil component, which produces cleaner
burning. The ratio of each ingredient varies depending on the performance
required and it is usually the nitromethane component that is adjusted.
A common maximum mix would be 70% methanol. 15%
oil and 15% nitro. The other nitro ratios commercially available are 5%,
10% and 30%.
What type of Radio is required?
It is possible to use a standard
aeroplane 4-channel radio but this is not recommended. Ideally, 5 servos
are required. A servo being the geared electric motor and crank that directly
controls a particular function of the helicopter. The five servos control
the 1.Throttle, 2.Tail Rotor (rudder), 3. Collective (controls the pitch
of the main rotor or rate of climb), 4.Fore/aft Cyclic of the main rotor
and 5.left/ right cyclic of main rotor (the last two functions initiate
and control forward and sideways movement when hovering as well as climb
and roll in forward flight).
Most modem computer radios
are reasonably priced and can store the set up for various models as well
as fixed wing by disabling the special helicopter functions.
What is the range of the Radio?
The range of model aircraft
radios is about 1000 metres or one kilometre. This may not seem far, but
the real limit is one of visibility. When a model helicopter is 300 metres
away it is already beginning to look like a fly buzzing around and if you
can't see it properly you can't fly it properly!
What is a Gyro?
Gyros or gyroscopes are used
to stabilise the tail of a model helicopter. Without a gyro the tail tends
to swing violently from side to side and is easily effected by wind gusts.
As the name suggests a gyro consists of a fast spinning flywheel which
senses any movement of the helicopter. There are now also available electronic
gyros that have no moving parts. Also available is a Gyro with a heading
lock setting for 3d aerobatics to keep the tail heading constant even whilst
flying backwards.
How long does a tank of fuel last?
The length of time a model
helicopter can fly is limited by the size of the fuel tank and the capacity
of the engine. The time varies from about 12 minutes to about 20 minutes.
This is usually quite long enough due to the concentration level required
when flying.
Is it hard to fly a Model Helicopter?
The answer is definitely NO,
provided you choose the right kit you get some help and do the right ground
work. The time to learn varies depending on ones abilities, but typical
times are about two months (assuming you practice once a week). The first
step is to learn to hover, as this is an important part of controlling
the model when landing and taking off. The next step is to begin to do
figure eights and gain confidence in controlling the helicopter when it
is flying towards you.
There are various aids to minimise
the risk to the helicopter when learning. These include Trainer Under-carts
that allow hard landings and minimise the likelihood of the helicopter
flipping over from a wrong control input by the pilot. There are also excellent
Computer Simulators available that allows you to practice when the weather's
too wet to go to the field and also eliminates any fear of damaging the
helicopter if you want to try something daring.
Can Helicopters glide?
Just like the full size, in
the unlikely event an engine quits or if the pilot may wish to intentionally
'glide' the helicopter this is easily achieved. The manoeuvre involves
applying negative Pitch to the main rotor (this causes the rotor to maintain
rotation as the helicopter descends). Then when the helicopter is a couple
of metres above the ground, positive pitch is gradually applied. The energy
stored in the spinning rotor is used to slow the descent and allow a gentle
touch down. It is as simple as that, well almost, this manoeuvre does take
some time to master.
Where can I fly a model helicopter?
Model helicopters are not toys
and are potentially dangerous if flown carelessly. The temptation to fly
in the backyard or local park (which is a breach of local council by laws)
should be avoided at all costs. Loss of control due to pilot error or people
or animals approaching out of curiosity can very quickly develop into a
very dangerous situation.
It is strongly recommended
that you join a club. In this way you can learn from others and fly in
complete safety without any distractions.
How much do they cost?
Depending on the kit, engine
and radio the initial cost can vary enormously. Generally, to get started
a good second hand package can be had for under a $1,000. New packages
can be purchased from under $2,000.
Is there a Club?
We do have one Helicopter Club
in Melbourne that has about 60 members. The Melbourne Radio Controlled
Helicopter Club, which operates from St Leonard's College next to the
Frankston freeway
from about 10.00am Saturdays and Sundays, weather permitting.
"Where
to find the Club site"
Click Here
Where can I buy a Model Helicopter?
If you are starting out it
is recommended you buy from a reputable hobby shop or dealer. Buying second
hand privately you risk being disappointed, as you will not know for sure
if the radio or helicopter are in good order or obsolete. Once you have
gained experience, you will know what to look for and check out, if you
wish to purchase a second hand helicopter.
Australian modelling magazines
(available at any newsagents) list State by State hobby shops and contact
numbers near the back cover. These magazines have a section devoted to
model helicopters and usually model shops that sell model helicopters have
advertisements near by.