Author Topic: Ground Run Jabiru 33OOa  (Read 211 times)

Bil438

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  • Engine: Jabiru 3300 120 hp
  • Sonerai Model: II LS
Ground Run Jabiru 33OOa
« on: Jun 10, 2017 »
For some reason I wired the left mag clockwise the right mag opposite, say 3 years ago. Its not as hard to get wrong as you'd think.

Needless to say the mag drop was huge.

The mags are close to the firewall so the ground run dragged on for 3 hours, though time running did not exceed 15 minutes. Once the leads are shorted out the engine's performance is breathtaking. It starts instantly, You get 20 psi oil pressure on the starter.
The details
The start procedure is to switch master on, fuel pump on , choke full on and throttle idle. Either spin it or hand-pull it through say 6 blades, This draws rich fuel/air into the carb to feed those 6 cylinders. (Jabiru 3300a)
Once the mags are switched on, it bursts to life say instantly and has a fair bark even at idle. No muffler. Yet The exhaust note is not offensive even at higher  power settings.
Once it catches the idle is left at idle until the choke can be slowly eased off. This might take a  minute or more.
Idle oil pressure is 80 psi cold on SAE W80+ oil. Oil temp didn't move much even though there is a thermostat.
Because it's a racer/aerobat the throttle travel from idle to takeoff is maybe 25 degrees and the lever is short.  The butterfly is spring loaded to takeoff so that if the mechanism broke (UNLIKELY) THE ENGINE GOES TO TAKEOFF POWER so you can keep flying. It's not a Kawasaki throttle, but close to it. Kawasaki bikes have a 2 position throttle "ON & OFF". The Sonerai/ J33OO has 3 positions Idle, Cruise and Takeoff.
The alternator output breaker was set on before start and the Field Breaker closed after start. The voltage then showed say 14V and the charge say 15 amps. We'd been playing start for some time . The charge limit on those SLA Batteries is 5 amps. If I'd taken the battery down that far I'd charge at 2 amps before flying, or reduce the RPM to get 5 amps off the alternator.
Power: It hard to imagine it being anything less than 130 hp. Our Sonerai was tied to a 2' diameter maple. Even so I thought the tree leaned just a little with the throttle open.
The CHT got to 250F and the EGT maybe to 1000F at 2000rpm. Above 2OOO rpm you lose your coat, shoes, glasses and so on. Lawn chairs learn to fly.
My prop was a Jabiru hoop-pine prop, Today we over-torqued it which crushed the hub at 12 ft lbs.  Torque should be maybe 7 ft lbs on 3/8 -24 bolts. We should have asked.
Even so Gord Larsen has a spare GT Prop so it will get the nod. GT Prop I think.
Once we lost a little power after a climb test with the  J2200 engine and needed to do a survivors circuit to land. Part of the reason for so much power is that if you lose a little, it  doesn;t matter. It will fly happily on 5O% and climb out on 6O%.

So... today was a high point in a 3 year engine conversion. If we can stay in the groove, flying this June remains possible. Bill Evans

Wayne O.

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Re: Ground Run Jabiru 33OOa
« Reply #1 on: Jun 11, 2017 »
what is the weight with this engine?

Bil438

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Re: Ground Run Jabiru 33OOa
« Reply #2 on: Jun 12, 2017 »
It weighed 529 with the Jabiru 2200a engine and the J33OO weighs 5O lbs more so Nominally 58O. I'll be happy if I get airborne at 6OO. The Hoerner Tip Tanks weigh 5 lbs each so maybe 61O.
I'll let you know when I get the wings on and weigh it. Bill

 

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