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Unpacking Day - November 20, 2007
I spent the better part of 1
1/2 hours unpacking the airplane. The big box was made of heavy corrugated cardboard with a wood frame and generous use
of foam padding throughout.
The engine cowling came in its own box and when opened really gave me an indication
as to the size of the plane. I am used to .40-.60 sized airplanes and this is my first giant.
The wing panels were
packed in a separate shipping box and, as the main crate, were very well packed. There was no damage to any part of the airplane.
It took another hour to cut up the box, disassemble the wood crate frame and discard all the packing. The week, my friend
Mike asked of I had the box for the Yak laying around as he wanted it to ship a plane he'd sold. Sorry Mike, the box has
been recycled! Oops!
The wings and horizontal stab/elevators come with their own carrying bags. While not custom
cloth and lined like may expensive bags you can buy, these will do a good job until they wear out or someone buys me custom
made bags. (hint hint) They also served well as shipping packing/protection for the long trip from the factory.
So far, so good. A review of the assembly manual is next up.
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The "Yakmobile" - November 27, 2007
The Yak cannot be carried in a 1992 Ford
Escort. No way. After that little car had been in our family for 16 years, it started nickle and diming me with problems like
a bum ignition switch, leaking rack and pinion unit and most concerning, hard shifting with the auto-transmission. Time to
look for another car; one that would also serve as transport for the Yak.
Enter the Yak mobile; a 2002 Dodge Grand
Caravan EX. I started looking around one weekend and by the end of the following week, this particular one ended up in the
driveway.
With quad seating and a third row bench seat, yes, I can haul seven people around in it, but that wasn't
the reason I bought it. Those extra seats, as you might imagine are coming out, allowing for adequate room to transport the
plane, field box, gas, etc. to/from the field. It will also come in handy to haul bags of mulch and other large household
items. After I sold my 1994 Dodge pickup a couple years ago, we really missed having something with utility, so the van fills
multiple roles nicely
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Hinging 101 - December 23, 2007
The Yak employs the Robart Hinge Point system. This is a
unique type of hinge that has been around the hobby for a number of years and work vey well for many types of airplanes. I
had never used them before. The Yak uses 22 of the Super Hinge Point #309. I want this plane to be the best I can make it and I am fortuneate to have a fellow club member, Mike Barbee willing to
help me work through some of the unfamiliar areas of giant scale aircraft construction.
So, it was on the Sunday
before Christmas 2007 that I made the short trip to Mike's to learn to properly install a hing point. This where I also
learned to add microballoons to the epoxy mix to fatten up the solution and see just where all that epoxy is going. When it's
white, it's a lot easier to see when you spill it on the airplane.
Hinging is largely completed by the factory. You
have to ensure fit and glue the hinge points into place. Alignment of the hinge is key to eliminating binding. Installation
depth is important to minimizing unnecessary gaps in the hinge line and to afford proper hinge operation.
We did
the horizontal stabs only and the rest was up to me. Technique and care are important. Take your time as there's
nothing gained by rushing, having only to re-work the task.
Check out Mike's website at www.monsterhanger.com. As an aside, Mike and I are both private pilots with Mike having just purchased an absolutely beautiful fully restored 1946
Aeronca Champ. Check it out here.
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Elevator Work Continues - December 29, 2007
The elevator hinges needed to be
completed from the afternoon learning session at Mike's. With that now completed, the hinge gaps needed to be sealed to
eliminate potential flutter. The gaps on both elevators was minimal as a result of a good hinging job, but Mike recommended
sealing them anyway. I agreed.
Tip: Before gluing the hinges into the
control surfaces, apply some vaseline to the hinge pin area. This will keep glue from getting into and sticking to the rotating
part of the assembly, making the hinge stiff.
Use the Robart drill guide to
drill straight holes in your control surfaces.
Gap sealing was a new procedure as the 40-60 size planes
previously didn't really need it. The Yak is a big bird and sealing the gap was pretty easy. Cutting a 1" wide strip
of clear Monokote the length of the hinge line and ironing it into the gap is all that is needed. The strip was first folded
in half and the hinges marked on it. Using a hole punch, a semicircle was punched into the Monokote at the marks. This allows
the hinge point to work freely with the seal in place except at the rotating hinge. That's a new trick for my finishing
toolbox.
I took some shots of the process below.
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Control Horn Installation
The last item to do this afternoon was to install the dual control horns
on both elevators. These assemblies are a 3 piece affair employing 2 parallel control horns and a baseplate, all made of fiberglass.
The horn slots are already made in the control surfaces. Accessing the slots required only cutting the covering away and removing
it from the area where the baseplate will be epoxied into place. Here again, ample amounts of expanded epoxy are mixed and
poured into the control horn slots. On a couple, I mized a bit too much hardener and the mix began setting up a bit too quickly.
I had to work quickly and ended up mixing a second batch to do some of the other surfaces.
Here are a few
pictures of the preparation and final appearance of the installed horns.
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Elevator servo installation is next up as well as gas proofing
the exposed wood on the edges of the horizontal stab. Stay tuned for more progress on the log.
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Hinge Gap Seals and Fuel Proofing Completed - January 16, 2008
During
the holidays, I got a fair amount of work done on the Yak, then reality set back in with January 2 rolling around. Ugh...
back to the work grind. No time to play in the shop during the weeknights as I was not home much.
I spent a little
time in the shop this past weekend finishing up the hinge gap sealing on the ailerons and rudder As I worked on the sealing
task, I got better with each subsequent sealing effort. By the time I got to the ailerons and rudder, the seals looked really
good.
Hinges can be sealed a couple ways. The least expensive method is to use a strip of clear Monokote cut into
a strip that will fit inside the hinge bevel area. I used a regular Monokote iron to seal it up. There is a sealing iron made
for smaller areas, but on this giant, there was plenty of room to work.
The other method involves using Blenderm Tape; a clear adhesive-backed tape used in the medical field. This tape is actually specified by name in the assembly manual,
but I found Monokote to be fine and less costly.
I got a coat of finish grade epoxy on the horizontal stab roots
as well as the servo tray area for each elevator, per the instruction manual. Apparently, over time exhaust gets back into
this area and sealing it up helps extend the life of the airframe. The wing root rib area was also sealed; my idea.
The Desert Aircraft prop drill guide arrived this week - a required item when you want to drill straight and true holes into a $30+ propeller.
Moreso if you use a carbon fiber product, which seem to be quite popular these days.
Stay tuned for more progress reports.
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Engine Fitting, Landing Gear, Pull-Pull Cable, Rudder Servo - February 28, 2008
Sorry
to say this is the first oppurtunity I've had in, yes, 2 months to sit down and update the website. This update is getting
accomplished while I am on a business trip. I highly recommend the City Cafe Diner in downtown Chattanooga at the corner of MLK Blvd. & Carter. Open 24 x 7.
More work has been completed on
the project, so here we go.
I pulled the DA50-R out of the box one afternoon decided to dry-fit it to the firewall.
All indications were it would fit as intended and I'd be surprised if there was a problem. There wasn't thankfully.
Using the provided drilling template and instruction manual, I carefully drilled the fiberglass reinforced firewall. The alignment
of the holes I drilled with the motor mount was perfect.
While there are countless ways to install servos for
throttle & choke function, I decided to install the throttle servo as the manual suggests for the DA-50. A pair
of hardwood rails were measured, cut and epoxied into place to raise the servo such that the engine header didn't hit
it on the other side of the motorbox. The installation is illustrated below in the photos. The manual doesn't address
a choke servo, but I decided to put one in just to make setting the choke easier and it eliminated the need to fabricate a
manual level system that would have to protrude through the cowling somewhere.
The exterior and interior of the
motor box have been coated with finish cure clear coat epoxy per the manual.
Here are a few pictures of the firewall,
motor box and the DA-50 with the throttle servo in place. The servo is a standard size, ball bearing Hitec. Same for the choke.
I haven't figured just how I am going to do that servo at this time, so I'll post it when I do.
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Landing Gear Assembly
The landing gear is quite beefy, painted black, made of
aluminum and was assembled with the spats provided in the kit. I've seen many of the EFRC Yaks running without the
spats and I decided to put them on anyway. The added weight isn't a concern and they add scale appearance to the plane.
The wheels are Sullivan S852 and are 4" in diameter. These are very wheelss you need to assemble, unlike most you just slide on the axle. The kit consists
of the 2 tires, 4 hubs and Sullivan's "Delrin" bearings. Sullivan also includes 6 socket head cap
screws, nuts and lock washers to clamp the hubs to the tire. Blue Loc-tite was used on the screws. You need your own axles.
I used the Dubro #249.
Attachment of the gear to the fuselage was easy. I epoxied the exposed wood on the outside of the fuse with
20 minute finish cure clear coat to keep gas and oil from softening the wood. I then marked the holes using a transfer punch to ensure centered holes. There is a pre-installed aluminum bracket inside the fuse that you drill clean through from the
outside. Once all the holes are drilled, you can install the gear with the provided hardware. This is one tough gear installation.
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Cutting
a Carbon Fiber SpinnerI bought
the Pete Model 4" carbon fiber spinner for this project. This kit consists of an uncut 100% carbon fiber spinner, aluminum backplate
and 6 socket head machine screws to attach the spinner to the backplate. This helps reduce weight and it's pretty nice
looking too.
You need to cut your own spinner with these types and I'd never done one before, so I measured
about 10 times, then remeasured and verified some more before I applied the home made template to the virgin spinner cone.
With a spinner that costs $75, you can't be too careful.
The spinner CANNOT touch the propeller at any point.
Since the prop flexes a bit, if it touches the spinner, the spinner may break.
A contour gauge is essential if you're going to get a good template from your efforts. The one I linked to in the website here is
better than the one I used and has more slats that make for a more defined contour.
Drilling the propeller was
pretty easy. I bought the proper prop drill guide from Desert Aircraft and, after making sure the engine's piston, spinner
backplate and prop were all in alignment, I drilled the holes in the prop. Be careful, as you need to have the prop begin
the compression stroke of the engine such that you'll be able to flip it from a comfortable position to get the engine
started. Failure to do so can leave you with a prop you cannot use; a costly mistake. The wood prop in the photos is a 24
x 8 and cost $24. Similar carbon fiber props cost upwards of $100 or more.
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Rudder Servo Installation with Pul-Pull Control
The rudder on airplanes like this is
usually controlled with one or more servos operating in harmony. The EFRC 88" Yak requires but one servo, a 4" SWB control arm and 2 cables that you make up from the supplied cable and fittings in the hardware kit. The rudder cables at the servo are
not done at this time.
I am using the Hitec HS-5955TG servo for the rudder as well as for aileron and elevator control. These servos are coreless digital units with dual
ball bearings andtitanium gears and have 250 oz./in. of torque at 4.8 volts and 333 oz/in. at 6 volts.
They are
and can be programmed with Hitec's HFP-10 or the new HFP-20 programmer. Dig deep because the programmer costs about $150 with the newest unit, the dash 20 at $170. Ironically, mine
was inoperative out of the box, even though it was brand new. As this is written, a free replacement unit is on the UPS truck
bound for my house.
Servos can be had at EFRC for less than street price but you can't get the lower price unless it's part of an airplane package. Street price
for these servos is about $115 each. You'll need five. Don't skimp on quality servos for giant airplanes or you'll
be sorry.
As an aside to the rudder assembly, the tailwheel was also installed over the past several weeks too.
This is a carbon fiber bracket with stainless hardware and a quality tire.
That's about it for now. I hop to get some more work
done this weekend with additional photos. Drop me a note if you like what you see or find any bad links or other information
on the site. Thanks 
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Servo Installation- March 7, 2008
With the blizzard of 2008 raging outside, this past Saturday was the time to head downstairs and get some more work done on the Yak. So, the following
post the the build log focuses on that task.
Sorry about the photo quality, everyone. The Cybershot is almost 6
years old and I think a replacement with a good macro function would do the site some justice. If anyone has a suggestion
on a camera that won't leave me in the poorhouse, I'm listening.
Hitec HFP-20 Servo Programmer
This little gizmo is a real time saver and is great for centering servos for installation, along with numerous other programming
and testing functions. At $155, the HFP-20 is not a low-cost shop item, but is quite valuable for troubleshooting as
well. The HFP-20 replaces the slightly older HFP-10. The basic difference between the two? The -20 can program advanced features
in the 7xxx series digital servos. As of March 2008, Tower Hobbies had them both the same price.
HFP-10/20 Product
Links
Specs on the HFP-10
Specs on the HFP-20
Rudder Servo
On my last post, I showed photos of the rudder servo having been installed. You'll
notice I used the big honkin' SWB servo arm that guarantees full deflection of the Yak's massive rudder. Today, I finished things up with that by completing
the pull-pull cable terminations at the servo as illustrated in the gallery below. That done, time to move on to the elevators.
I might add here that Chris at Extreme Flight strongly advises the use of Loctite Blue(aka #242) on ALL nut/bolt assemblies and for good reason. By the time this bad boy is ready to go to the field for its maiden
flight, you do NOT want things vibrating apart. The SWB servo arms are not only attached with the conventional means
via the output shaft screw on the servo, but are also held with clamping screws on the SWB arms; all of which need to be treated
with Loctite.
For a datasheet on Loctite 242, click here.
Elevator Servos
The Yak requires one servo for each elevator control surface; common on
giant RC planes. The little slot provided in the servo installation rib was too narrow for the twisted trio of wires on the
Hitec HS5955TGservo, so after taking to the rib with a razor saw and Exacto #11 blade, the issue of a too-narrow slot was solved. A flat,
ribbon-like wire such as Spektrum, Futaba and others would be fine here. I used the SWB servo arms recommended by Chris
at Extreme Flight. Installation of the servo, control arm was not difficult, despite the rather tight fit of the
servo inside the horizontal stabilizer. A lot of giants have the elevator servos installed on the outside of the fuse, but
not the Yak. The supplied ball links and titanium control rods are high quality and I would like to see them on my next plane
as well.
Aileron Servos
Of the three control surfaces, the aileron servos were the easiest
to do. With everything right out in plain view and totally easy access, the installation went quickly. As you can see from
the photo, I managed to scrape up the covering, not realizing the bolt was long. When I checked the control with the HFP-20,
ssscccrrraaatttttcchhhhh! Ouch!  Easily repaired, though. Flipping the bolt around was the solution.
Control rods and ball links are
also from the supplied hardware kit. You will need two servo extensions, at least 12 inches in length. If they need to be
longer, you can always make your own with some #22 AWG servo wire, a soldering iron and some heat shrink tubing. Simply use the existing extension and insert more length with the required
amount of wire. I would not recommend the use of "butt splices" to make these connections. They're okay for
your kids' car stereo, but I wouldn't use them in the airplane.
With these tasks done and out of the way,
I think I will take on the choke servo installation design on the next visit to the shop. That will complete all servo
installations and I can get on with other work. The choke servo is more of a "nice to have" function than a necessity
and makes operation easier I think.
Please go to Page 2 for more of the Build Log.
Thanks for stopping
by!
-Rick 
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