Ultralight aircraft in cabin heater for Rotax aircooled engines
AP-BIW* heater unit
for Challenger *AP-BIW = AIN'T PRETTY BUT IT WORKS
Here's a side view showing the three
existing Rotax cover screws that were used to secure the
plastic (lexan) heat
collector. The entire box is made of scrap lexan that was
cut out with scissors. Most of it is actually a single
piece, bent along the lines to form the right angles, then
taped with SNOWBOARD REPAIR TAPE to strengthen the bends.
Snowboard repair tape is a thick,
clear tape that is incredibly pliable even in very cold
weather and is very sticky. I think it's fantastic. I bought
a role of it that was a foot wide, so I can cut it any way I
want to.
View from rear. Back is
attached only by one screw.
The larger picture (click the little one) shows better where
I've used one of the head bolts to attach the heater in the
area of the spark plugs.
I taped only the bottom portion of
the heat collector because I was too anxious to go flying and,
besides, taping clear lexan is boring.
Looking up from front
area. Just another view showing where the side of the
collector is attached to the Rotax using
two of the existing motor cover screws. The cheapy dryer hose
is both clamped and taped to the lexan box. I formed a
cylinder from a separate piece of lexan as a hose attachment
and then taped it to the open end of the collector box with
some of that snowboard tape. Actually, most of Cloud Dancer is
held together with it. Just kidding.
Click on pictures for larger view!
The cheapy dryer duct
hose enters the cockpit
here. I cut out a half-moon shaped opening in the aluminum
sheet and applied a strip of vinyl edging . . . the type you
buy to protect car door edges. This keeps vibration from
allowing the aluminum to cut through the plastic hose. There
was just enough room here for the ducting to enter alongside
all the wiring and the fuel lines.
Doesn't look like it,
but there's plenty of room to pull the dryer hose up past the
seat and suspend it where it will be positioned between your
legs. The stick has full clearance because
the flexible hose is, well, flexible. It moves an inch or two
either way, or back and forth, as the stick moves.
This makes for comfy feetsies and the
heat seems to build in the cockpit better when it moves from
the front to the back. With both doors on, my CI gets cozy!
Rotax 447 in cabin heater, Rotax 503 in cabin heater, Rotax
aircooled engine cabine heater.
VENTILATING SYSTEM FOR CHALLENGER A BIT OF
THEORY
WINTER
SUMMER
In winter, warm air is pushed
through cylinder cowl, into the fabric duct, then redirected by
the baffle into the heater box and down into the 4 inch aluminum
duct in the cabin.
In summer, fresh air flows into the air scoop and is redirected by
the baffle into the 4 inch round aluminum duct in the cabin.
WINTER TOO WARM
SUMMER TOO COLD
In winter, when the cabin gets too
hot or in summer when the cabin gets to cold, a push pull control
cable moves the baffle to expel the air out.
THE CHALLENGER SYSTEM
This system is based on the
standard heat box used before on air-cooled motor airplanes.
OPERATION
Warm air is pushed out of the
cylinder cowl and transferred via a fabric duct to a control box.
From this box, via a remotely controlled baffle, air is directed
inside through a conduit or expelled outside. The fabric duct is
interchangeable with an air scoop. Fresh ram air caught by this
scoop is sent to the box and controlled the same way as described
before.
COMPARISON
Heaters that are attached to the
motor all have the same problem vibration! It's just a matter of
time. Our heater box sits on the two lower curved ribs under the
motor, considerably reducing the vibration. Test have shown our
heater box will survive many years before it needs servicing.
Many Challenger owners had to lower the top rib
to be able to install their heater box on the motor. This
modification alters the air flow very close to the propeller and
could add turbulence in this area, producing more vibrations and
slightly reducing the prop's efficiency.
With our system, the fabric duct uses the resilient space between
the top rib and cylinder cowl, entirely closing this gap. Many
Challenger owners had complained about the fact they had to remove
the heater box from the cowling to service the plugs.
With our system, removal of the fabric duct is easy since it's
attached to the cowling with Velcro.
By covering the cylinder cowl, warm air outlet and spark plug
area, the system collects all the warm air that's possible to
retrieve from the motor. In our test, at -10° F, we were able to
keep inside temperature to 50°F, quite comfortable.
THE FABRIC DUCT
Made of oil, UV and cold crack resistant fabric, the duct is
resistant to all weather.
It is also very easy to clean. Velcro at both
ends simplify its installation.
THE AIR SCOOP
Made with the same fabric, the scoop is solidly attached to the
heater box rendering it impossible to be thrown into the prop.
THE HEATER BOX
Made from
composite, the heater box is light and rugged. The box sits on a
base to permit its
installation directly on the lower curved ribs. Again, Velcro is
used to attach the base to the ribs.
A 4 inch flange, under the base, accepts 4 inch
aluminum tubing, with solid tubing preferred. Inside, a fabric
controlled baffle directs air out of or into the cabin via the
base flange.
The control arm and baffle frame are from
galvanized steel. The heater box can be painted with your color
choice. The complete heater box assembly weighs just under a
pound.
COVERS
To complete winterization, the under motor and firewall areas have
to
be
totally closed. If not properly closed, warm air will be sucked
out rendering it impossible to heat up the cabin.
We supply two covers with every kit, one for the
rear section and one to cover front part and the firewall section.
(For now these covers are adjusted to fit the
new Challenger version.)
CONTROL CABLE
The control cable is a push pull type. Its length, 156 inches is
more than enough to install the control knob at a convenient
location of your choice.
HARDWARE SUPPLIED
Except for the aluminum tubing, everything needed is included. The
tube can be easily bought locally for a price lower than its
shipping cost.
INSTALLATION
To make it easy to install, even with the motor installed,
self-adhesive Velcro is used. The only important task is to clean
all areas before attaching any Velcro.
The box is also clamped to the aluminum tube and
control cable rendering it impossible to fly into the prop. All
Velcro attached to the cylinder cowl is secured with pop rivets at
both ends.
Instructions are complete including several drawings.
NOTE
Our heater box has been installed
and tested on our plane for 5 years now (over 350 hrs) and has
never needed servicing. It is a cool idea in summer and a warm
experience in winter.
MODEL:
HBK1 for CHALLENGER I $295.00 CDN
HBK2 for CHALLENGER II $295.00 CDN
Ultralight
News
PO Box 1710 Holland
Landing Ontario
L9N 1P2 647-723-8767
Airfield
1895 10th line east of Hwy 11 Bradford Ontario
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Ontario Canada L9N 1P2 647-723-8767.
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installation directly on the lower curved ribs. Again, Velcro is
used to attach the base to the ribs.
be
totally closed. If not properly closed, warm air will be sucked
out rendering it impossible to heat up the cabin. 
