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Pipe, Fuel Tank and Smoke Tank Rework
Updated April 22, 2008 (continued from page 2 of the log)
The other issue found myself debating was the use of
two 20 oz. tanks; one for gas, the other smoke oil. After giving the subject a lot of thought, I decided to lay the one 20
oz. tank back over so it could be more fully filled with gas. The other tank would come out and be replaced with a Sullivan
12 oz rectangular seamless tank. You don't need as much smoke oil as gas and this seemed to me to be a better solution.
It also lightens up the airplane.
So, out came the tanks and the plumbing. The photos provided in this section
show that I also decided to use Tygon fuel tubing instead of neoprene. After discussing with Mike Barbee and a couple other
guys at the shop, I decided I'd go with the Tygon for various reasons. For one, you can see fluid flow through the clear
yellow tubing. Not so with Neoprene. Yes, Tygon hardens over time. So change it when it does. You should be looking inside
the plane anyway. While Neoprene has its good points, so does Tygon. Neoprene also has been reported to "fleck-off"
black particles which have been found in various Walbro carbs and in the fuel system. That is primarily what made me pull
the neoprene. The arguments continue to rage on the RC forums on the subject of Tygon vs. Neoprene. And so it goes...
Tanks as you can see from the photos below are in and all the plumbing done. Filters were installed on the fill lines to
further protect engine and smoke pump from contamination. These are both 3 line systems; 1 vent, 1 fill, 1 draw line each.
Even though the Tygon slipped over the fittings snugly, I used wire ties on practically all fittings to ensure they will stay
put. The vent lines pass through the floor of the pipe tunnel and past the pipe. They then exit the fuselage through two light
plywood guides. These were my idea mainly as a means to keep the lines in a fixed position to safely and effectively vent
overboard when filling the tanks.
The tanks sit on 1/2" latex foam taped to the floor of the fuse. The tanks
are also secured to the latex foam with a couple squares of double-sided tape for each. I didn't want them slipping forward
on landings. Two pieces of red 1" wide Velcro secure the pair of tanks to the fuse floor. This is a good secure installation
and I am glad I reworked it, even though it took a couple hours to make it so.
The fuel dots are an effective and
fairly low cost way to secure filling lines. There are numerous fuel dots and fancier fueling systems, but I saw no need to
go beyond the $17.95 I paid for the pair. You can spend $30+ each for polished dots that don't work any better.
Check out the photos below. You can click them to enlarge.
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Smoke Pump Installation
Mike suggested the smoke pump
be mounted up front in the motor box. I think his logic related to the fact that if I started mounting stuff behind the main
spar, the CG was going to be seriously affected in the negative. Simply stated, the heavy stuff has to go up front.
The installation of a smoke system was my idea and while it's not part of the Extreme Flight package, I thought its
use would add a nice appearance in flight. The overall system is pretty simple; smoke tank, smoke oil, electric pump.
The oil is pumped from the tank and directly into the exhaust header (see picture) where it does a slow burn on
the way down the pipe and out the exhaust to form a thick white plume of smoke. Special smoke oil is made for this purpose,
but you can also mix your own although I have no plans to do the latter.
I tested the Sullivan 753 Smoke Writer pump outside the airframe. This was suggested by the Sullivan folks in their instructions and I agree it's the best way
to go. It was also a great way for me to learn how all the electronics interfaces with the radio, battery switch harnesses,
etc. Water works great as a test fluid.
The 753 thinks like a servo. Its pump rate is dependent on two things;
battery supply voltage and signal drive level from the receiver. Proportional control is probably the best way to see the
adjustable flow rate the unit is capable of. I am using the AUX 1 channel on my Spektrum DX7 radio. The pump requires at least
4.8 VDC, but works up to 12 VDC. I am still undecided on the battery I will use. I tested the system using a 7.4 V battery with
a 6 V regulator. With the smoke system, the aircraft will have 4 on- batteries; rx, servos, ignition, smoke pump.
Wow!
Plumbing requirements are easy and striaghtforward. The kit includes line clamps, safety wires, line reducers
and a check valve to prevent the pump from losing its prime during periods of non use.
Mounting was straightforward.
I used 4, 4-40 screws, locking nuts and washers.
Here are a few pictures below that show the pump and some of the
plumbing. It's getting crowded in here.
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Avionics Installation
The avionics for this project
are, in my experience, extensive. I will eventually post a drawing that illustrates how everything is wired. For now, I'm
just to the point where I am installing all the goodies that help to make this thing fly.
The avionics to be installed
consists of the following:
One, Spektrum AR9000 receiver
Two, 7.2V Duralite lithium-manganese radio and power
expander battery packs
One, 7.2 Duralite lithium-ion ignition battery pack
Two, 6V, 7.5 amp Duralite regulators
with switch harnesses
One, EDR-111 Power Bus Expander
One, EDR-107 fiber optic remote engine kill switch
One,
Sullivan 753 Skywriter smoke pump
One, Duralite electronic ignition switch
I will have more photos as
the avionics installation progresses. Switch installation and the addition of the final smoke pump battery and its switch
are also still to be installed.
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That's where I am as of April 22nd. Things are coming together pretty well. Stay tuned for more progress
reports as I am now on the downhill side of the assembly of the Yak-54 from Exterem Flight RC.
-Rick 
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