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Power Plant

[82 hrs]

November 30

After weighing up the pros and cons of various engines for the BushCaddy R80 I have decided on the Jabiru 3300 and have traded in my 2200 which came out of my X-Air. Jason at Jabiru has been most helpful with his advice and assistance and so today it was delivered to the workshop.
The Jabiru 3300cc Aircraft Engine is a 6-cylinder 4-stroke horizontally opposed air cooled engine. Overall dimensions are extremely small. It's 596mm (23.46") width allows tractor applications with very small frontal areas. The Jabiru engine is designed for either tractor or pusher installation. At 81kg installed weight the Jabiru 3300 Aircraft Engine is an ideal replacement for the 100-120 hp equivalent which power many of the existing "
experimental" aircraft. It is an engine designed by aircraft designers for aircraft applications!

March 18, 22, 23 & 24

The engine mounting bracket and nose wheel I purchased with the kit was constructed for a Rotax 912. However since then I have decided to install the Jabiru 3300 to add Australian content and because I believe the certified engine is better than a Rotax. This means major modification to the engine mounts and in particular the nose wheel assembly so the engine can be installed as close as possible to the firewall and not interfere with the front nose wheel. When constructing the engine mounting frame I have used a jig made from timber on which I will mount all engine mounts and cut the chrome molly pipe to fit. I will drill the holes for for the front wheel spring when the engine has been mounted.

The Jabiru 3300 is being held into its temporary position with a chain block while working out the distance from the firewall so the heater, air filter and other components can be installed behind the engine without interfering with the nose wheel or other components.
TIP: Make sure the airframe is level before starting to construct the engine mounting frame and also the front wheel assembly is both vertical as well as the bracket above the wheel base is horizontal. This will give you the correct angle from the firewall to the ground. I have used timber chocks to keep the wheel at its correct angle.
The starter motor is mounted on the top of the engine while means the centre of the prop will be 40mm below the trust line, I could have made a special housing for the starter motor to be above the cowl but thought it would look out of place. With the engine mounting pins 200mm from the firewall, there is plenty of room for all the engine fittings and the exhaust which will not interfere with the front nose wheel and the dual exhaust pipes will extend down close to the firewall.
One method of constructing the engine mounts is to make a face plate to the correct dimensions for the engine mount location points and secure the pins so they don't move at the correct distance from the firewall. Secure the front landing wheel into position so the chrome-molly tubing can be cut and shaped to fit neatly around the locating pins for the firewall and for the engine mounts.
TIP: Grind the edges of the tubing so they form an exact fit to the pins and where two or more tubes come together, cut and weld gussets to help take the forces with the engine running.

April 20, 21, 25 & 29

The engine mount is now supporting the engine while the battery, starter solenoid, oil filter bottle, fuel pump, gascolator, hot air mixer and cabin heater box are fitted into position.
TIP: Mount all equipment first before fitting the spring for the nose wheel to ensure the weight is correct.
From the left side, the first item is the oil breather / filter bottle that takes the overflow from head. Next to that is the battery and housing with the strap to prevent movement. Above that and to the right is the starter solenoid and under the batter is the fuel pump. The image on the right shows the hot-air mixer that allows fresh air into the carby, or hot air when carby heat is turned on.
TIP: Mark and setout all components before drilling holes. An additional support will be required behind the firewall.
Forming the cowl takes some effort and is a real balancing act making sure the nose remains level and preventing the metal skin from getting a kink.
TIP: Mark and cut the holes for the exhaust pipes and the nose wheel first before forming the metal to fit the nose.
The images show the bottom section of the cowl fixed into position and an intake to allow airflow over the oil cooler.  The cowl has to be easily removed to allow for oil changes and engine maintenance.
TIP: Continually check the nose is horizontal to the floor before drilling any holes or trimming the metal skin. I put self locking nuts every 50mm around the nose bowl and although this is too many, the cowl is solid and won't move. 

With the engine mounting bracket removed the components for the Jabiru 3300 can be secured into position. The hot air mixture box has been placed at an angle to allow the scat hose intake for fresh air and hot air not to be fouled by the engine mounting brackets. The starter solenoid has been placed close to the battery terminals to reduce resistance and the fuel pump close to the gasolator.
TIP: Use gasket cement under the hot air mixture box to form a seal against the firewall so the filter can supply clean air to the carby. Gasket cement can also be used behind the cabin heater box to form a seal when it is riveted to the firewall. Mark and cut the hole for the gasolator making sure the stem does not protrude past the cowl.

May 3 & 4

There are four (4) engine mounts for the Jabiru engine with rubber bushing to reduce vibration and support the engine.
TIP: Use a G-clamp to compress the rubber bushes so the bolt can extend past the aluminum plate so the nut can be screwed onto the bolt.
The cowl is hinged at the top to allow for engine inspection. Two (2) clamps are used to secure the top panel into position.
TIP: The bottom section of the cowl is made from 0.020" while the top hinged panels are made from 0.016" for flexibility.

September 13, 16, 20, 26 & 30

The ramair ducts need as much clear air as possible and fiber glass air scoops should be constructed using all the nose air intake.
TIP: Make a mold of the nose intake first then hand shape the scoop using layers of fiber glass matting and compound onto the ram air ducts so it is one complete unit.

While shaping the air intake scoop to the ramair ducts, make sure there is enough clearance between the oil filter and the air scoop so it can be removed without having to undo the whole air duct.  You may also have to fiberglass the existing holes for the spark plugs and move the hole so the hole and rubber grommet aligns without air leaks.
 
 
For the ramair ducts to work efficiently, the hole that allowed the nose to fit over the prop shaft will have to be sealed.
TIP: Take a flat piece of fiberglass and use a holesaw to cut the hole about 1/2" diameter larger then the prop shaft. Cut the sheet in half and shape to you have sufficient material to allow 3/16" bolts to secure the two halves to the back of the nose. Make sure the propeller bolts and guides are inserted from the back before bolting the two halves into position.
While tightening the propeller bolts to 8 ft lbs. in a diagonal pattern, use a strip of aluminum clamped to the front wheel as a guide to make sure the prop tracks evenly. Place a red mark on the aluminum so that it aligns with the tip of the prop. Turn the prop by hand and the tip of the other blade should align with the red mark if the prop is tracking correctly. 
The original spinner was for a Jabiru 2.2 and would not fit properly and direct air into the intakes as the spinner diameter was too small. The spinner has a front and back plate.
TIP: Attach with a couple of screws making adjustments until the spinner runs true at the lowest revs. Keep doing this process until all screws have been inserted.
The front wheel axle is held into position with two split pins, preventing it from sliding out and releasing the front wheel from its mounts. If you are concerned about the prospect of the split pins becoming dislodged or breaking, cut a collar to go over the axel each side and drill a 3/16" hole through the collar and axel and use an AN3 bolt and nylock to secure it in position.
 

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