Electrics - 2009/02

RDRC Fly for Tots charity fly-in
February 2009 113
Electrics Greg Gimlick | [email protected]
Also included in this column:
• Arming switches
• Keystone Indoor Electric Fly
report
• Motor poles
Exactly 219 pilots attended and brought more than 700 aircraft of all
shapes and sizes. Although this isn’t an electric meet, the number of
electric-powered airplanes at the event continues to grow. This year’s
fleet included everything from park models to Bob Violett Models jets.
With factory pilots from Horizon Hobby and other competition
teams doing demonstrations, there was never a dull moment. Jeff Foley
brought his full-scale Stearman and raffled off rides; his profits were
donated to the charity as well.
Above: Sgt. Roger Flannegan takes his reenlistment
oath at Fly for Tots event while
all veterans present stand behind him. The
author was proud to be in the group. Dustin
Hedrick photo.
Right: Fly for Tots is a huge event that
grows yearly. This aerial shot was taken
early Saturday, before the whole crowd
arrived. That Cub on the runway is 1/2 scale.
Hedrick photo.
Below: This is the inside of the dome used
for the KIEF event, and the photo doesn’t
even show the other third of it. It’s huge!
Bob Aberle photo.
TAKING OFF: It hardly seems possible
that this is the February issue already, but I
guess that’s a sign of old age. The election
is over and we may have another month or
two before the 2012 campaign begins, so
let’s talk airplanes!
Fly for Tots: The Raleigh-Durham Radio
Control club (RDRC) held its Fly for Tots
Children’s Charity Fly-In in late September
here in North Carolina. This has been an
annual event for the last 18 years or so, and
Larry Lewis, along with the rest of the club,
does an outstanding job. The gathering has
grown each year, and the club gives 100%
of all profits to charity, which for the last
two years has been the Victory Junction
Gang Camp.
02sig4.QXD 12/22/08 12:31 PM Page 113
Anderson Powerpoles. The cost is $10, and
it can be built into a hatch or scale
accessory so that it’s hidden and
accessible.
The beauty of this setup is its pure
simplicity. There are no switches to fail or
get knocked. The model can have its motor
battery plugged in and assembled while the
airplane is in the pits or on display, but
there is no way the motor can be activated
until the plug is physically pushed into the
connector.
You can make one if you’re so inclined
or don’t want to spend $10. But these
switches from MPi are nicely made and
well worth the price by the time you
purchase all the connectors separately to
make one.
One great suggestion and method for
arming came from Mark Qvale. He was
concerned about the safety of his electrics
and, being an engineer, he took it upon himself to do some
research.
After coming up with his idea, Mark ran it by the people at
Castle Creations because he was going to alter one of the
company’s controllers to use his method. They told him they
didn’t see any problem with it, and he has used it successfully for
months since doing the modification.
One of the things we discussed was the need to check with the
ESC manufacturer before altering the radio wire. This technique
depends on the ESC allowing no signal from the radio to the ESC
and programming the speed control to disengage any signal to the
motor without a proper radio signal.
With Mark’s switch placed where it is, the signal from the
radio is blocked and the ESC won’t arm the motor. This allows
him to check all of his controls, etc. without the motor armed.
Not all controllers are so solid in their performance when a
radio signal is lost or blocked, and that’s why you need to check
with the manufacturer before using this method. Prudence would
suggest thoroughly bench-testing your system.
Robert Vess of Vess Aero did his part as the master of
ceremonies and kept the action moving along nicely with many
RDRC members’ help. He also gave demos with his KingCat jet
and offered his usual high level of expertise to anyone needing or
asking for help.
Robert is the brain behind Vess Propellers. He taught at North
Carolina State University’s aerospace engineering school before
moving on to aerodynamic development for some of the top teams
in NASCAR.
A moving event within the event was the re-enlistment of 15-
year Army Sergeant Roger Flannegan from Bravo Company 3rd
VSTV in Fort Bragg, North Carolina. He re-enlisted for the fourth
time Saturday at show center, with all veterans who were present
standing on the flightline. Extreme Flight JR Team member Lee
Morey hovered his 110-inch Extreme Flight Yak-54 in the
background.
As a retired Army veteran, I was thrilled that Sgt. Flannegan
chose the Fly for Tots event as the place of his re-enlistment and
requested all of us old vets to stand behind him. He will serve his
fourth tour of duty in Iraq later this year, and I wish him luck and
another safe return.
The real magic this weekend was the final tally for the charity:
$25,000. All that money goes directly to the Victory Junction
Gang Camp.
If you can work it into your schedule this fall, you owe it to
yourself to attend this event. The AMA was well represented
there by its president, executive vice president, district vice
president, and several others.
Thanks to Dustin Hedrick for his photos and all the RDRC
gang for putting on a great event!
Arming Switches: Several months ago, I wrote briefly about
arming switches, mostly referring to larger electrics. Instead of
going into depth, I referenced Greg Covey’s article on
RCUniverse, because it was so thorough and I know him well
enough to know he’s dead on with his information. See the
“Sources” listing for the Web article address.
That generated several e-mails and many great ideas and
suggestions. I heard from people who hate the idea of arming
switches and those who wouldn’t fly without one.
In the latter group were some who bought commercially
available units and others who wired their own. One reader who
makes his living doing failure-mode analysis provided some
excellent food for thought on the various methods.
The bottom line is that there is no consensus. That’s okay, and
ESC manufacturers have left the issue up to the end user after
years of making various arming devices, only to have users cut
them off or bypass them.
The method I like most in my airplanes is the version available
from Maxx Products International (MPi). Model 6970 comes with
Deans Ultra Plugs installed, and model 6980 comes with
114 MODEL AVIATION
Above: This is the arming
harness from MPi that the
author uses in his big
models. It is available for
Deans or APP connectors.
Left: The small outrunner
disassembled in the
foreground has 12 magnets;
therefore, it is a 12-pole
motor. That’s required
information for Eagle
Tree’s software calibration.
BATT
SW
S
G+
DPST
Batt Connector
MOTOR
BEC
RX
4,5,6 etc
Batt
1
2
3
ESC
Mark Qvale provided this diagram of his arming system. A switch interrupts the
connection of the ESC to the receiver.
02sig4.QXD 12/22/08 12:34 PM Page 114
Thanks for your suggestions about
arming switches. I believe in them and use
them in all of my large models.
Keystone Indoor Electric Fly (KIEF): MA
technical editor and longtime friend, Bob
Aberle, wrote me the other day to report
on the KIEF event held in Pennsylvania in
late October. It came along at a great time,
since many indoor fliers were left without
a venue when the JR Indoor Electric
Festival had to be canceled because of a
windstorm that blew down and destroyed
the dome.
For a full report on the KIEF, point
your browser toward the RC Micro World
Online Magazine. The “Sources” listing
contains the address.
I’ll be adding this to my list of places
to go this year, because the flying facility
looks perfect. It’s huge and sectioned off
into three areas, to keep the micros from
being eaten up by the larger models and 3-
D flyers.
I asked Bob what the restrictions were,
and he said:
“Basically the ground rule was that the
park flyer type and 3-D models were
limited to a 16-ounce flying weight. But in
several cases a few very slow flyers were
allowed to fly at 20 and 21 ounces at the
discretion of the CD. On the micro end we
set 6 ounces as the max limit.
“Keep in mind that there are two floor
to ceiling nets that separate the larger
models on one end and the micro airplanes
at the other. That still leaves the center
stage at 300 by 200 feet with an 85 feet
ceiling.”
This could become a big event, and one
of the things I like about it is that it’s not a
commercial gathering. Although those are
fun to attend, sometimes the regular ol’
pilots get lost in the production and it’s no
longer a flier’s event. Since the KIEF had
80 pilots its first time, it looks like it will
be popular.
Check out the Cloud 9 Web site and
take a look at the RC Micro World Online
Magazine while you’re there. There is lots
of good info if micro-flying is your thing.
How Many Poles Are in a Motor? Since
writing about my Eagle Tree Systems data
logger a few months ago, I’ve gotten some
e-mails asking how a user is supposed to
determine how many poles a motor has.
This information is required when you set
up your computer program so it will
interpret the data correctly.
The easiest way to determine the
number of poles is to read the
documentation for the motor; it is hoped
that the information will be there. If it
isn’t, a method is described in the
instruction manual from Eagle Tree.
That’s a kind way of saying, “Read the
instructions closely.” But in case you
missed it, following is the section of the
manual describing how.
“To calibrate the RPM sensor, you
need to know the number of ‘poles’ your
brushless motor has. This information is
normally supplied by the motor
manufacturer. For outrunner motors, the
term ‘poles’ refers to the number of
magnets in the motor (not the number of
stator teeth, ‘legs,’ or ‘hammerheads’).
For example, if you have an outrunner
with 10 teeth on the stator and 14 magnets
in the flux ring, the motor has 14 poles.
For inrunner motors with a central
magnet, the term ‘poles’ refers to the
number of magnetic poles present on each
magnet (always 2, so enter a ‘2’ for
poles).
“If you are uncertain about the number
of poles, or want to verify you calculated
correctly, a hand-held tachometer can be
used to compare the RPM value displayed
real-time by your recorder, in a bench test
(assuming it is safe for you to do this).
Real-time display is available in Recorder
USB Live Mode, on the MicroPower
PowerPanel, or with the Seagull Wireless
Dashboard. If the value displayed is
incorrect, you can change the poles setting
to adjust the displayed RPM value. For
example, if your handheld tachometer
reads 4000 RPM, and your Eagle Tree
data shows the maximum RPM of 8000,
you would need to double the number of
poles by 2.”
There you have it, easier than most of
us try to make it.
Eagle Tree Systems has great support,
and of all the data loggers I’ve tried, I find
this company’s to be the easiest to set up
and use. Nothing against the others, but
the support available from Eagle Tree has
proven to be great when I’ve asked
questions.
Final Approach: That’s it; the space is
gone and it’s time to head for the shop. I
hope to see many of you at the WRAM
Show and Toledo R/C Expo in the near
future. MA
Sources:
Fly for Tots
www.flyfortots.com
Victory Junction Gang Camp
(877) 854-2267
www.victoryjunction.org
Vess Aero
www.vessaero.com
Greg Covey’s article in Amp’d Issue 2:
“Arming the Big Boys”:
www.rcuniverse.com/magazine/article_displa
y.cfm?article_id=950
Maxx Products International
(847) 438-2233
www.maxxprod.com
Keystone Indoor Electric Event coverage:
www.cloud9rc.com/kief
Eagle Tree Systems
(425) 614-0450
www.eagletreesystems.com
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