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TIPS & TRICKS
to balance rotor blades with no special equipment
We all need to balance the main
rotor blades of our helicopters, as this is an essential part of the
mechanical setup, and because if the blades are not balanced correctly, the helicopter will
not fly well, and may not even fly at all.
There are several different types
of commercially available tools to help you do this task, but items such
as a blade balancer will cost around £10 or more. You can
do this without purchasing such items
There are two parts to balancing
rotor blades. Each is described briefly below...
1 - Find the centre of gravity
of EACH BLADE INDIVIDUALLY
This means getting something on
which you can balance a single rotor blade to find its balance point at
the centre. Once found, you mark that point with a pencil or marker pen
or similar, then repeat for the second blade. Check to ensure that BOTH BLADES have the same point of
balance along their length.
If they don't have the same balance
point, you need to add weight to the outer end of the blade that has the
balance point further INWARDS TOWARD THE ROOT until they do match
exactly. Most of use something like coloured electrical tape for
The easiest way to find the centre
of balance of a blade is to
find an old Stanley knife blade or similar, and an old piece of 1 inch or 2 inch
square wood about 4 inches long. Use a hobby hacksaw, or even the
Stanley knife itself to score a thin groove across the wood just wide
enough and deep enough to let you force the old Stanley knife blade into
it with the BLADE side UPWARDS. If necessary, glue the blade into
place, although you should not need to do so.
Now you have a perfect fulcrum to
lay the blades across and to let you find the balance point.
2 - Balance EACH BLADE against
the other BLADE
This needs a little more work, but
basically all you are doing is ensuring that each blade weighs exactly
the same as the other blade. If they don't, you add weight to the CENTRE
OF THE LIGHTER BLADE where the centre of balance is for that blade.
That is why you marked it in step 1 !
The easiest way to do this is to
get a piece of nice STRAIGHT threaded rod the same diameter as the bolt that holds
your blades onto the head. It only needs to be about 6 inches
long. You will also need a pair of nuts to fit the thread.
Slide the rod through the mounting
holes of both blades, ensuring that the leading edges point in OPPOSITE
directions (as if they are fitted to your helicopter). Tighten the
nuts up on either side so that the blades cannot move by themselves, and
get them as straight as you possibly can, as if they were fitted on your
Now find a couple of old tins, or
jars or pieces of smooth wood, or whatever that are both the same height and
are smooth enough so that they will let
the outer ends of the rod roll freely. Put the blades on the
supports with the blades as horizontally level as possible, and wait for them to
settle until they are totally still. Then use a ruler or whatever
else you have to measure the distance of both tips from the bench.
When they are both the same YOU ARE FINISHED.
Make sure that the bench is
level. If it is not level you can still do this by measuring the
height of both blades, and then repeating it with the blades pointing
the opposite way by simply turning them around on the supports. If
the measurements you take are the same at both ends as previously, then
if you think about it, they are in balance.
hope this makes balancing your blades a little easier and cheaper.