Radio Control Helicopters - 2008/01

HI ALL. Now that we are in the full grip of winter, it is a good
time to discuss indoor electric models. I have included some
pictures from E-Fest 2007 to get you excited about that event.
Unless you just entered the hobby, you probably know that
micro electrics have been the fastest-growing segment for
sometime. Along with being cheaper, easier to fix, and safer,
they are tons of fun to fly.
New indoor events are popping up like mushrooms across the
country. Enthusiastic electric-power fliers are making deals with
building owners to use their space for RC aircraft. There is
nothing like having a large, heated area in which to fly when it is
cold outside.There are two major indoor events in the Midwest at roughly
this time. The JR Indoor Electric Festival was held November 2-4
in Columbus, Ohio, and the Great Planes E-Fest will take place
February 9-10.
I heard a rumor that there is going to be a mega indoor fun-fly
in the University of Phoenix football dome this year. Now that is
taking it to the next level for sure.
(Editor’s note: This event is called the Electric Flight Expo,
and it will be held April 25-27, 2008.)
If you have a chance to go to this inaugural event, by all
means be there. If you have not experienced a large indoor RC
event, attend one before this winter flying season is over. You
will be amazed by how much you gain from attending one. Notonly is it a lot of fun, but the amount of knowledge and helpful
information exchanged is phenomenal.
This is where you meet and rub elbows with the top pilots in the
country. The nice thing is that most of them are very friendly and
will take time to help you with any aspect of your helicopter.
Even though they might fly for a different company, it is okay to
ask them to help you. Their job is to help anyone, no matter what
brand they fly. So do not be bashful; just ask politely for their
assistance. You might be surprised by how responsive they are.
Help! I think I’m gonna give up this frustrating hobby!
You are not alone if you feel this way. I have said it myself.
Sometimes you get into a “funk” where everything just seems togo wrong. When you fly, you crash. When
you are building, nothing is going together
right. Your parts order that was supposed
to show up the Friday before the fun-fly
comes the following Monday.
Anyone who has been in the hobby for
a while probably knows what I am
describing. At these times it seems like a
black cloud is hanging over you.
I mentioned awhile back that some
months I feel like I am writing a column
that gets sent into a black hole. With little
feedback from the readers, I cannot be
sure I am really communicating with
anyone.
I recently received a letter from
somebody in Jonesburg, Missouri, so that
proves that at least one person is reading
this stuff. He is having some problems
getting his helicopter going, and following
is what he wrote.
“No, you’re not sending useless
information down a black hole. Your
helicopter articles are the first ones I read
every time I get my Model Aviation
magazine.
“My problem with helicopters is that
everything I read is tailored for the
advanced flyers. I bought a great little book
on helicopters, but about all it did was
define a lot of the words that you hear in
the heli world. Actually I needed that, but
as far as setting up pitch curves and throttle
holds (etc.) … I still haven’t a clue.
“The guy I bought the helicopter from
got me partially set up, and I was able to
do some hovering, but there is a lot more
to setting this up. I’ve got about $1,500
wrapped up in this hangar queen, with
batteries going dead and fuel going bad.
“Do you think that once in a while, you
could throw guys like me a bone, and give
us some basic information on how to get
started?”
I was glad to receive this letter because
it brought some things to my attention. I
have had a running theme in this column
that tends to appeal to more advanced
pilots. I am going to make a point of
including some of the basics to help pilots
who are just earning their wings.
Balancing Stuff: We might as well get
right to it. Whether you are an expert or
you are taking your first steps on the
yellow brick road to helicopter bliss, there
is one crucial thing you must do: balance
your whirling, spinning, rotating
components.
Three things need to be balanced on
your helicopter for it to fly smoothly: the
main rotor head, the tail rotor, and the fan,
or drive, system. I know many people
never balance anything, but their
helicopters wear out much faster and they
have more failures of other parts because
of excess vibration.
The main rotor head is generally going
to produce the most visible vibration on
the helicopter if things are out of whack.
Canopy vibration, tail bouncing, and skid
vibes are some of the prominent effects.
Rotor-head speeds are roughly 2,000
rpm. Vibrations at that frequency are easy
for the human eye to see.
Much has been written about balancing
rotor heads. The system I use is the same
as car-tire balancers; it is called “dynamic
balancing.” That means the head is
balanced while in rotation. That is the best
way.
There are other ways to static-balance
the head, but they are a waste of time and
here is why. You have to take the wholehead off the helicopter and put it in a
balancer. Then after you are finished, if
one main blade leads or lags you will have a
shake because the dynamic balance is off.
I believe that only dynamic balance is
important, and I’m going to describe how I
adjust it. Promise me you will not laugh! I
use a roll of black electrical tape.
Years ago everyone at the field used to
laugh at me when I stuck different lengths
of tape on my model’s blades and spooled
up to check the balance. It does work,
though, and remember when you drive
down the road in your car that it is smooth
because of dynamic balancing. There are
little bits of weight on your wheels just like
the little pieces of electrical tape I use on
the rotor head.
The following is a reply I made to
someone who was fighting a canopy
vibration.
“The canopy vibes are most likely from
the rotor head as well. A quick way to check
it out is to take off and hover and note the
amount of canopy vibration, then put a 4-
inch piece of electrical tape on a blade or a
paddle at its CG or near it. Take off again
and see if the vibes are worse or better.
“Move the tape from blade to paddle so
you can check which blade/paddle is out of
balance by checking the vibe level. After
you isolate the one that reduces the vibes
the most then put another 4 inches ofelectrical tape on the same blade/paddle.
“If the vibes are more, then you know to
reduce the amount of tape. If the vibes are
again less then you can try even some more
tape. Trial and error until you get it as
smooth as possible.
“Every one of my machines has
electrical tape on it for balance. My friends
used to make fun of me but now they all
have balancing tape of some kind on their
machines too. If you want it to look nice
then figure out how much tape you need and
substitute the same amount of weight with
matching MonoKote trim tape on the under
side of the blade/paddle.
“Let us know if that gets rid of the vibes.”
I did get a reply from him that the
vibrations were gone.
This technique is not always going to
work because canopy shakes can come from
a variety of sources. This is just one easy
way to check for head imbalance that
requires no disassembly. It is convenient
and accurate. Next time we will get into the
tail and drivetrain balance issues.
That is all I have space for this time. I will
try to include tips such as this every other
month or so. Please write and let me know
if this is the direction you would like to see
the column heading. Thanks for reading.
Sources:
Electric Flight Expo
www.efexpo.com
Great Planes E-Fest
www.gpe-fest.com
JR Indoor Electric Festival
www.jriefestival.com