In cabin heater, aircraft in cabin heater, Rotax air cooled engine in cabin heater, in cabin heater for Rotax 377, Rotax 447, Rotax 503 engines.

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Light Sport & Ultralight Aircraft Information

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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) heatChallenger heater 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. Heater for Challenger ultralight 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 usinChallenger heater pictureg 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 cockpitChallenger ultralight heater 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.




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.



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.


This system is based on the standard heat box used before on air-cooled motor airplanes.


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.


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. THE HEATER BOX

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 50F, quite comfortable.


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.

Made with the same fabric, the scoop is solidly attached to the heater box rendering it impossible to be thrown into the prop.


Made from composite, the heater box is light and rugged. The box sits on a base to permit itsTHE HEATER BOX 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.


To complete winterization, the under motor and firewall areas have to THE HEATER BOXbe 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.)


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.

Except for the aluminum tubing, everything needed is included. The tube can be easily bought locally for a price lower than its shipping cost.
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.


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.


HBK1 for CHALLENGER I   $295.00


HBK2 for CHALLENGER II $295.00