Electrics - 2008/08

Greg is building the Approach Engineering Cobra.
It is again available, from “Dr. Tim” Dawson
through Starwood Scale Models. Incredible kit!
Approach Engineering is under Scale great Dr. Tim’s care
August 2008 121
Electrics Greg Gimlick | [email protected]
TAKING OFF: I just got back from the Toledo Weak Signals show
and am still filtering through all the photos and such. I had planned to
do more coverage of it this month, but I landed in the hospital the day
after I got back. So everything is running a little behind, and I don’t
want to be late with the deadline; you know how those editors will take
the stick to us.
I’ll fill in with some specifics in the next few columns as space
permits. You can see my photos of the show online.
Approach Engineering: I reported in December that James Linder,
the brain and talent behind Approach Engineering, had been killed in
an Apache crash. I am pleased to report that his wife and children are
doing well and moving on as best they can, and so is his dream of
providing incredible balsa-built kits for scale helicopters.
Tim Dawson, or “Dr. Tim” as he is known throughout the forums
and online community, is a Scale-helicopter guru, RC Heli magazine
Scale columnist, and all-around good guy. He has bought the company,
and it will be back in production by the time you read this. Dr. Tim
brings a ton of knowledge and passion to this venture, and that’s a
fitting tribute to James.
Distribution will be through Starwood Models and other companies
as the line continues to grow. Dr. Tim does some tech support for
Starwood, so chances are that you might have talked to him if you’ve
called the company.
I was in the middle of building one of the electric Cobras when
James was killed and the company’s future went into limbo. But now
that it’s back and growing, that project will rise again and continue.
If you are a Scale helicopter fan or if you have thought about
producing a Scale helicopter and the high price of molded-fiberglassfuselage
kits scared you, you’ll be excited to see how inexpensively
you can build one of these incredible kits.
Dr. Tim also owns Super Scale, which makes molded accessories
for various scale helicopters. So the future looks bright for James’s
dream to continue, and we’ll all be the benefactors.
Xtreme Power Systems: Visiting with Jim Drew and Scott Bahde of
Xtreme Power Systems (XPS) during the Toledo Show was a highlight
for me. I began using the Multiplex Royal Evo as my primary radio
several years ago, when it first came on the market. For my use, it was
the most versatile radio available in terms of programmability and
features.
The Evo allowed me to program any switch or stick to any function
I wanted, and I could mix them however I wanted. I was no longer
bound by convention; for a particular
need or desire, I was one very happy boy
because I could make the Evo do what I
wanted.
The radio had an internal frequency
scanner that was invaluable and wouldn’t
let me transmit a signal if the frequency
was in use as determined by the scanner.
It was synthesized, so I could choose
whatever frequency I needed at the field.
Now we step forward, the onslaught of 2.4 GHz radios has
happened, and my Evo has been relegated to “second fiddle” status.
However, XPS has made XtremeLink conversion modules and
receivers that allow us to easily convert almost any radio we have to
the new 2.4 GHz standard.
I picked up a system for my Royal Evo, and it was only a fiveminute
task to put my love back on top of the radio stack. Let’s look at
how the XtremeLink works, and then I’ll take you through the steps to
convert the Evo.
The system operates on the 2.4 GHz band and uses a “proprietary
spherical RF radiation pattern,” eliminating the need for multiple
receiver antennas. On the eight-channel receiver I have, you can see
the small vertical antenna; that is the only one it needs. The smaller
six-channel park flyer receiver shows no exterior antenna at all.
XtremeLink uses all available frequencies in the ISM band through
an “advanced proprietary predictive frequency hopping technique.” In
simple terms, that means it doesn’t lock onto two frequencies and stay
there; it will hop to another frequency when it predicts a problem on
one of the chosen frequencies.
The systems use a proprietary technology to determine each
signal’s strength and change if it doesn’t meet their criteria. With the
number of available frequencies and the ability to change, that means
we could have 120 XPS systems operating at the same time without
fear of interference.
So what are the odds of being on the same frequency as another
radio? How about one in 18,446,744,073,709,552,000? I like those
odds.
The XtremeLink transmitter module offers many options the end
user can program to make it legal in a variety of countries. One such
parameter is the adjustable output power from 10mw (legal anywhere
in the world that allows 2.4 GHz) up to 100mw of power (in the US
Also included
in this column:
• XPS rescues
the Evo radio
• Toledo Weak
Signals’ show
Greg obtained the XPS XtremeLink
system to convert his Multiplex
Royal Evo to the new 2.4 GHz
standard. Six- and eight-channel
receivers are at the bottom.
122 MODEL AVIATION
and select other countries). The module also uses less than 90 mA,
which increases your transmitter battery life roughly five times
compared to 72 MHz radio-frequency modules.
XPS uses bidirectional communication between the transmitter
module and the receiver. Because of this, and its 65,536 16-bit system,
there will eventually be telemetry options and possibly even video and
audio features in the near future. The XtremeLink’s features are as
follows.
Radio speed (effective throughput): 256 Kbps
Frequency hopping: Yes (only when interference is predicted)
Specified range: 5 miles
Resolution: 65,536 (16 bits)
Number of systems that can be in use simultaneously: 120
Integrated single antenna: Yes
Real-time, built-in telemetry interface: Yes
Bidirectional communications: Yes
Receivers available or pending (number of channels): 3, 6, 8, 10, 12, 16
Module pricing (MSRP of transmitter module/receiver): $149-$219
Receiver pricing (MSRP of receivers): $59-$149
Latency (measured from stick input to receiver output): 2ms to 1 frame
Fail-safe programmable for each channel: Yes
Operating voltage range: 3.5-30.0
Product warranty: Lifetime
I’ll let the photos tell the story of the installation in my Royal Evo;
it’s that simple. To see a real-time video of the process, go to my Web
site under the RC section. Following is a rundown of the procedure.
1) Open the back of the radio.
2) Push the antenna down and out of the holder tube.
3) Unplug the RF module from the main board.
4) Slide the new XPS antenna up through the tube until it snaps into
place.
5) Plug the connector into the main board.
Above: When you open the back, you
can see the circuit board for the original
72 MHz band and the frequency
scanner board that is piggybacked to it.
These will be removed.
Right: The 72 MHz board lifts straight
off the connector pins on the main
board. Pull up straight, and it comes
right off. The original antenna just
pushed out the bottom of the tube you
see in the middle of the radio.
Left: New antenna
attached to XPS 2.4
GHz module is slid up
through the antenna
tube until it snaps in
place. Velcro will be
placed on main board
where old module was
removed to hold the
new one in place.
Left: Everything is
complete. Plug the
new board into the
socket and secure with
Velcro on the back.
The conversion takes
roughly five minutes.
The programming
button for the module
can be seen to the
right of the connector.
6) Lay the module flat on the main board and hold with provided
Velcro.
7) Be sure to route the antenna coax wire out of the way before
you close the back.
As do all the 2.4 GHz radios I’ve looked at, the XtremeLink
requires you to bind the receiver to the transmitter. This involves
holding the program button down on the module while powering on
the transmitter. When the light turns green, release the button and it
will begin flashing orange while it looks for a receiver to which to
bind.
Power on the receiver and wait for the LED to flash red before
using a 3/32-inch Allen wrench to push the button on the receiver.
Release the button when it turns green. When both lights go to solid
green, the process is complete and the system is bound. Install the
receiver as described in the manual and range check.
As with all 2.4 GHz systems, the range-checking procedure is
different from what you might be used to with the 72 MHz radios;
be sure to follow the instructions closely, regardless of brand.
Following, directly from the instructions provided, is how to do the
Evo check.
1) Install the receiver in your airplane or helicopter.
2) Remove the antenna from the transmitter module.
3) Turn on the radio system.
4) Place the model on the ground so that the receiver antenna is
no less than 6 inches from the ground.
5) Hold your transmitter waist-high, away from your body.
6) Press and hold the PROG button on the transmitter module.
7) Walk completely around the RC device (360°) at a distance of
at least 50 feet, making sure that the transmitter-antenna connector
is pointed at the model. If you experience a pause in controls at any
time, try to reproduce it and release the button to see if the pause
happens. If the problem does not occur again, check to make sure
your receiver is at least 6 inches from the ground while testing.
8) With the PROG button still pressed, walk away from the
model until there is intermittent operation.
9) Turn the transmitter away from the model so that your body is
between the transmitter and the airplane. (The model should stop
responding completely.)
10) Without changing your positions, reinstall the antenna on
your transmitter module. (Do not release the PROG button.) The
model should now respond, even with your body in the way. If it
does not respond fully, do not fly!
So far I’ve flown my system in three different configurations
using the full-range, eight-channel receiver and two park flyer-rated
six-channel receivers, and I’ve had great
performance.
The six-channel receiver installed in my
aluminum-frame Corona helicopter is the
worst-case scenario because it violates at
least two criteria that XPS recommends, and
so far it’s been flawless.
When installing these receivers, keep all
wires secured away from the antenna. When
wires are allowed to move around or contact
the antenna, even getting close to it with
movement might cause them to change
tuning frequencies, thereby causing
interference. This is a simple insurance
measure that most of us ignore.
Final Approach: Some months the column
space is too short, and this is one of those
times. I could fill the whole issue with stuff I
got from the Toledo Show, and here I am on
the way to the Southeast Electric Flight
Festival and the Joe Nall fly-in in the next
three weeks. Busy times and nothing but
fun.
In the upcoming issues I’ll be looking at
some great new things from TME for the
Xtrema charger, along with the new
RealFlight G4 simulator and its electric
adaptability. MA
Sources:
Approach Engineering
www.approachengineering.com
Greg’s Toledo Show photos
www.gimlick.com
Starwood Models
(650) 851-9027
www.starwoodmodels.com
XPS
www.xtremepowersystems.net