Day Four, and it's time to leave the books behind. We were greeted with 3 engines (two 912's and one 912S) and a bunch of tools.
No race, no competition, just a group of people interested in learning what makes the engines work.
Roy and I teamed up on a 912. Roy is an instructor at the A&P school next door, they're thinking of making it part of the curriculum and he's here to learn about Rotax engines. He was kind enough to answer questions I had as we went along, too. We started by disassembling the back of the engine which contains the electrical equipment: rotor, stator, ignition triggers, starter, starter gearing, and also the water pump.
The engines use few gaskets, and most bolts are not safety wired, they fit just by the tight machining tolerances. Of course, that means taking them apart can really require some elbow grease....
In some cases, elbow grease just ain't enough.
The starter clutch is fascinating. Most GA airplanes use a Bendix type starter, which has some limitations. For instance, it's a delicate act of learning just when to back off the starter switch when the engine catches, and you can damage the starter if you accidentally engage it when doing a mag check at high rpm.
Rotax doesn't use a normal starter. Sure, they have a starter motor, but instead of the Bendix gear they use a really cool ring of egg shaped bearings/cams called a Sprag Clutch that is driven off friction from the starter gear, causing the bearings/cams to engage the crankshaft via friction. When the engine starts running the crankshaft advances ahead and off the bearings/cams, and the starter gear freewheels on the crankshaft. If the starter is accidentally reengaged it will spin the freewheeling starter gear, and the cams will just ride along the surface of the faster spinning crankshaft. I'd like to know who came up with that system.
The engine is built to such close tolerances there are very few gaskets in it, and very little sealer is even used. Even when sealer is used, barely any is applied. Here some Loctite is applied to the ignition housing assembly prior to reassembly.
During a break a gent brought in his newly flying airplane, using the new 912is fuel injected engine. Note how small the 912is is compared to a similar Continental or Lycoming engine.
Back to the shop, we've reinstalled the stator and timing triggers, and starter motor.
And the rotor/flywheel completes the assembly. No, we don't take them out and run them, but tomorrow we'll be taking cylinders off.
In the back of the shop, a pristine rebuilt 914 sits, waiting for a buyer. sigh.......
\
...
No race, no competition, just a group of people interested in learning what makes the engines work.
Roy and I teamed up on a 912. Roy is an instructor at the A&P school next door, they're thinking of making it part of the curriculum and he's here to learn about Rotax engines. He was kind enough to answer questions I had as we went along, too. We started by disassembling the back of the engine which contains the electrical equipment: rotor, stator, ignition triggers, starter, starter gearing, and also the water pump.
The engines use few gaskets, and most bolts are not safety wired, they fit just by the tight machining tolerances. Of course, that means taking them apart can really require some elbow grease....
In some cases, elbow grease just ain't enough.
The starter clutch is fascinating. Most GA airplanes use a Bendix type starter, which has some limitations. For instance, it's a delicate act of learning just when to back off the starter switch when the engine catches, and you can damage the starter if you accidentally engage it when doing a mag check at high rpm.
Rotax doesn't use a normal starter. Sure, they have a starter motor, but instead of the Bendix gear they use a really cool ring of egg shaped bearings/cams called a Sprag Clutch that is driven off friction from the starter gear, causing the bearings/cams to engage the crankshaft via friction. When the engine starts running the crankshaft advances ahead and off the bearings/cams, and the starter gear freewheels on the crankshaft. If the starter is accidentally reengaged it will spin the freewheeling starter gear, and the cams will just ride along the surface of the faster spinning crankshaft. I'd like to know who came up with that system.
The engine is built to such close tolerances there are very few gaskets in it, and very little sealer is even used. Even when sealer is used, barely any is applied. Here some Loctite is applied to the ignition housing assembly prior to reassembly.
During a break a gent brought in his newly flying airplane, using the new 912is fuel injected engine. Note how small the 912is is compared to a similar Continental or Lycoming engine.
Back to the shop, we've reinstalled the stator and timing triggers, and starter motor.
And the rotor/flywheel completes the assembly. No, we don't take them out and run them, but tomorrow we'll be taking cylinders off.
In the back of the shop, a pristine rebuilt 914 sits, waiting for a buyer. sigh.......
\
...
