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The Adventure Continues...
On This Page...
Header & pipe fitting
Throttle and choke
servos
Smoke & fuel tanks
Motor box hatch
Pipe, smoke tank, fuel tank rework
Exhaust Header, Tuned Pipe Fitting, Throttle and Choke
Servo Installation- March 28, 2008
New Camera Equipment
I'm now using a Sony Cyber-shot DSC-H3 8.1 megapixel camera. So please excuse the long load times for the pictures.
They are only 3 mp, but the resolution is apprently on the high side. The file properties show the size at about 1MB each.
As I learn what settings work best, the size should drop down later, making page loads a bit faster.
Throttle and Choke Servos
This week was spent (what little time it was) on figuring
out how the throttle and choke servos and their associated linkages would go in. I also wanted to get an idea as to how
the exhaust system was going to fit.
The servo of choice for both functions is the HiTEC HS-475HB. This standard size, analog sport servo features 76 oz/in. of torque at 4.8/6 volts; plenty for the duty they will see
in these applications. The output shaft is metal and should perform the job well. I used the control horns that came with
the HS-5955TG's, as I am using the SWB servo arms for rudder, aileron and elevators.
Extreme Flight made the throttle servo installation pretty easy. I did have to rotate the DA-50's carb 180 degrees to make
use of the servo hole in the engine box. This was discussed in the assembly manual. As well, a short email to DA
for a bit of guidance in that area helped. When rotating the carb, DO NOT rotate the black plastic block between it and
the engine casing. The carb attach screws need Loc-Tite and torque of 8 inch-pounds upon reassembly. Too tight and the seals
on this assembly will suck air. Sure enough, after rotating the carb, the pushrod linkage between it and the servo was a straight
shot as shown in the pictures below.
Ball Links Are Sweet Little Devices
I might mention
that this airplane makes 100% use of 4-40 ball links throughout and I must say while I am new to their use, I like the way they work; allowing for more articulation
of a pushrod setup. With a .60 size glow plane being the biggest thing I have built, the larger airplanes can't use the
lighter weight clevises, so bigger, more durable hardware must be employed. Pictures below tell the tale of installation.
Choke Servo
The choke servo was a bit of a trick, and in the end I hade to put a dog leg
bend in the pushrod, but because the ball links were used on both ends of the rod, the action is bind-free and smooth.
Setting servo travel will be part of the initial setup along with the throttle. Right now things are basically setup, but
fine tuning of all this is essential to a successful maiden flight. This whole choke servo thing was my idea and not part
of the kit or its instructions.
Exhaust System Initial Fitting
I dry fit everything
multiple times when I'm building; you know, measure twice, cut once. This is especially true of a large bird such
as this. For those of you reading and learning along with me on giants, this Yak is actually what I tell my friends is
an "entry-level" giant. If you take a look around at some of the websites I've listed on the Related Links page, you'll see what I mean. Check out the 3W engines at Cactus Aviation. So, 50cc's isn't big enough for you? If these guys haven't got what you need , I don't know what to tell
you. These aircraft get very large and the wallets of their owners need to be fairly fat to support them.
While
there was no cutting of the exhaust system, a small pipe mount made by Dave Brown Products shown below in the gallery needs to be positioned and firmly attached to the pipe tunnel also pictured. The pipe is then
attached to the mount with a securing device(device means I don't how I'm going to do that yet) to hold
the pipe in place. Usually it's a wire tie, but this pipe gets pretty hot, so something else may need to be used
to secure it. This is why you need to fit this stuff before you break out the drill, epoxy and blow torches. Okay, so no blow
torches were used in the making of this plane.
The header fit like a glove, but getting the rear header attach
bolt threaded and tight required the cutting of a sacrificial 5/32" allen wrench to stubby status to make the final tightening
turn. The front bolt is a no-brainer. With the header in place, it points straight down the pipe tunnel where the teflon coupler
will marry up to to the KS 1060 tuned pipe pictured below with the header. The KS pipe is a fine example of quality craftsmanship and excellent materials, as is the
DA-50 engine that will be benefitting from the exhaust upgrade. Check out the photos of the KS pipes when you visit their
site. A basic caninster muffler would have been just fine, but I've had piped engines on smaller planes and they rock!
Great power and performance is the reward for the extra expense.
Where to Put All That Avionics Gear?
My friend Mike Barbee and I may get together this weekend to discuss avionics installation. There is still much work yet
to be done before the plane is ready for tech inspection. The remaining work is focused solely on the fuselage where batteries,
switches, receiver, power box, smoke and fuel systems and other goodies will be installed. Weight and balance (primarily balance
- it won't be too heavy) are of prime importance. I'd rather place it once if possible, rather than reposition it
numerous times to get the CG right.
Check out the photos of this week's activity and I'll have more progress reports on the build to
post in the coming weeks. Thanks for stopping by.
-Rick 
Final Pipe Installation, Smoke and Fuel Tanks, Motorbox Hatch
Updated April 10, 2008
Please Note: The pictures I uploaded
on today's post are VGA grade; about 110kb each. Their smaller size allows for faster download to your PC but still pretty
good resolution. I had to do something as the 3MB pictures were taking too long to load and really weren't giving visitors
much more detail.
The Pipe
In order to get the KS-1060 pipe
installed once and for all, I needed to fabricate the relatively simple wood mount to which the Dave Brown pipe mount would
ultimately be attached. That didn't take long and after the epoxy set up, I was able to continue. This was detailed in
the assembly manual.
Things got interesting when I went to slide the pipe into the teflon sleeve at the header.
The pipe was hitting a piece of hardwood in the fuse and I had to improve the clearance. Otherwise, the hot pipe could cause
the wood to burn and I really didn't want that.
Exhaust systems on gas engines run hotter than their glow fueled
counterparts, so a wire tie normally strapped right to the pipe won't do here. I found a piece of neoprene gas fuel line,
slipped the wire tie into that, then attached to the pipe through the mount. I dont like the way it looks, although it'll
get the job done. KS makes a nice mount, but I'm not using it unless this doesn't work.
DA provided 2 very
strong spring clamps to hold the teflon coupling tight to the header/pipe. They are shown below with the other related photos.
The exhaust system is now installed.
I also took this time to mount the ignition system to the motorbox. That took
5 minutes. Done.
Click the pics below to view a larger image.
Hatch Access a Bit of a Chore But Works
With
2 servos and the batteries likely ending up all they way up front for CG as well, I really wanted to have easy access to the
inside of the large motorbox behind the firewall. And so it was that I embarked on the task of fabricating my own hatch-attach
method. The manual says it is not optional and that it adds a tremendous amount of strength to this part of the airframe.
Okay, so I'll make it strong.
The hatch was fitted with several hardwood rails that were epoxied onto the hatch
proper. The plan includes installing screws through the motorbox sides and into the rails. In addition, there are also a number
of screws attaching the hatch from the top and going down into the motorbox framework. In total, there are about 15 wood screws
with CA filled holes to make for a very tight fit; one I am confident will have no problem hold things tight up front.
I've seen this done on another EF Yak and the owner has had no problems.
A few pics below provide some detail
on this. I will have some additional shots once it's together on final assembly.
Click the pics to enlarge.
Smoke and Fuel Tank Assembly
I worked on
this Saturday night after getting back from Toledo. The plane came with a 20 oz. fuel tank and I wanted to have a smoke system
for my first giant, so I bought a second 20 ouncer and that will be used exclusively for the smoke system.
A brass tubing bender is a wonderful thing and you'll be hard pressed to bend the stuff without some sort of tool or
jig. Otherwise you'll kink it for sure. You also need a tubing cutter it you're going to make nice clean cuts. KS makes a nice low cost one you can get at your hobby shop along with that tubing bender which is essentially a spring you
slide the tubing into to keep it under pressure throughout the bending area.
After discussing fuel systems with
fellow modeler and club member Mike Barbee, I was convinced a 3 line system would be a good way to go. There are two and three
line systems to plumb fuel and smoke systems.
With a 2 line system, you have a vent line and a fuel delivery line.
A tee fitting is installed in the fuel line that goes to the tank. The tee is connected in series with the fuel line. The
"tee" part gets a piece of line connected to it and the other end is used to fill the tank. A device called a "fuel
dot" is commonly used to keep the open end of the fuel line closed and in place when not filling. It is frequently installed
on the side of the fuselage and can be made of aluminum or other materials.
With a 3 line system, you have a fuel
delivery line to the engine, another for venting and the last is dedicated as a fill line. This eliminates the need for
a tee fitting or check valve in the fill line if you're going to use the engine line to fill the tank like in a 2 line
system. The logic here is that with more plumbing fittings in the lines, there is more of a chance of system failure. 
The pictures I've uploaded to the page here depict the assembly of both tanks using the 3 line system. An
example of the fuel dot is also provided. Notice the clear identification of the tanks. The fueling ports on the plane will
also be well marked.
Well, that's about all I have to report for now. I
will be working on the plane this coming weekend and should have the fuel system and smoke pump installed. Of course, pictures
and build log narrative will follow.
Thanks for stopping by and checking in.
-Rick
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