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Welcome to Page 4 of the build log!
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Updated April 29, 2008
Avionics Installation Takes Most of the Day
With a lot more biz travel coming up in May and June, I really want to get the Yak completed. I
managed to get most of the remaining avionics gear laid out and installed Sunday April 27th before my next trip out. The Blog
for April 29th details the oh-so-fun return flight from Salt Lake to Columbus.
The Yak employs several independent battery
systems. Much of the reason behind this ties back to the old addage "never put all your eggs in one basket". And
so it is with high dollar giant scale model airplanes.
Here's the layout. A drawing will follow at some point
in the future. Battery 1 is for the receiver. Battery 2 is for the servo driver power box. Battery 3 runs the engine ignition
system and lastly, battery 4 serves the smoke pump. We don't power everyhting from one single battery because this sets
us up for the "single point of failure" mode. The receiver and power box batteries are already in and you go back
to Page 3 to see them. Today I installed the 2150 mah Duralite Plus Lithium Ion 2 cell, 7.4V pack along with the associated
ignition cutoff and the electronic switch/regulator. Pictures below.
This is the electronic ignition battery switch with a built-in 5.5V regulator. It controls a 2150 mah 7.4V lithium ion
pack.
 This is where the ignition switch/regulator is going to be installed.  The ignition switch is installed and ready to be wired to the battery and the EDR engine cut-off. The switch operates
on and off with sequential momentary presses of the button. This switch also has a built-in voltage monitor that tells you
when to stop flying and start charging. The engine cut-off is essentially another switch in series with the Powerbox switch
pictured above. The engine cut-off however, is controlled from the transmitter and allows the pilot to shut down the engine
on command. The smoke pump switch was also installed just below the ignition switch.
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Receiver and Power Bus Pro Switches InstalledThe
system, as you'll recall is equipped with 4 batteries. With 2 for the ignition and smoke pump done, I moved over the the
installation of the heavy duty receiver and power bus pro switches. These are just bigger higher current rated switches for
driving bigger servo loads. In reality, this plane does not really use that much more current to run the servos and radio,
but the regulators to which they are wired were part of the purchase. These switches and regulators are 2 identical units.
Switch cutout typical of both for the receiver and power bus pro units.
I made labels for each switch so I could remember which switch was which. I printed labels on officejet and made the
background black and gave the illusion of white ink. They are held on with sealing tape, then trimmed down to a smaller overall
patch on the fuse.
This is the other side of the fuse for the power bus pro
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That's about it for tonight. I will complete the build log later this week. Check back soon!
-Rick 
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Updated May 15, 2008
So, Where Did I Leave Off???I finally got some time while on the road to update the good ol' Yak Build Log tonight. Tonight's
"office" is the Fairfield Inn, Albuquerque, NM. Maybe I'll get a bit more done this weekend. Here's a few
more shots with narrative.
The EDR engine cutoff has been installed and taken up position adjacent to the ignition module up front. It's
been wrapped with foam for vibration isolation like most of the other avionics.
This is an interior shot of the motor-box showing the placement of the new ignition battery, lower right. This is a
2 cell, 2150 mah lithium ion pack from Duralite. All batteries on this plane are Duralite as well as the regulators.
This is the fully installed ignition switch with integrated regulator in the energized mode. The redLED
to the left is the EDR engine cutoff indicator. When on it indicates the ignition system is on. EDR supplied the engine cutoff
and servo power box.
Elevator servo extensions (2) head back into the cavernous fuselage. At this point, the stabs have been installed, connected
and tested for proper operation with the radio.
This is the Spektrum AR9100 receiver (left) and the EDR Power Bus Pro unit. When I first started installing all the
avionics, I though I would have a lot of room. With the installation nearly complete, I am finding that is not the case and
the CG may need to be adjusted. That's is one reason why I, like many, am putting all the batteries up front.
Speaking of batteries, here's a shot of the 2 Duralite packs; one for the receiver and the other for the Power Bus
Pro.
These are the Duralite 6 volt regulators. I bought the units with the integrated switch harness. A couple pieces of
Velcro securely hold them to the wing spar carry-through tube. Regulators should not be installed close to receivers even
though the regs have EMI/RFI radiation protection built in.
Spektrum RC uses a unique multiple receiver system in their 2.4 Ghz radios (above wrapped in foam). The AR9100 receiver
I am using can actually accept 2 additional receivers if so desired. The main receiver actually contains 2 receivers, so with
the auxiliary rx, I have 3.
That's all for now on the build log. Check back for more progress reports. It's
getting close be being finished. Stay tuned...
-Rick
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Rick Tressler - Columbus, Ohio
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