Actual Flying Rotax Installs

[Kai]

Yup,

Apprx 3/8” all around. It is excessive, though, for taking care of all engine movement on the isolators during both flight and start. However, a little extra clearance for the exhhust tailpipe is needed to get the verical split cowling on and off.

However, there is one other big however, I have seen R912 installations (especially pushers) where the motor is only supported on its four crankcase supports. They exhibit a lot more movement than my own installation.

Thx

[Skippydiesel]

Yup,

However, there is one other big however, I have seen R912 installations (especially pushers) where the motor is only supported on its four crankcase supports. They exhibit a lot more movement than my own installation.

Thx

My guess - the ring mount, with its widely spaced rubber isolators, will control rotational movement, very well but may be subject to "droop" over time. The latest Sonex adapter looks to allow upper engine rotational movement but is unlikely to droop at the prop.

[Kai]

Don’t guess- make sure!

Hang your engine mount on some kind of support, and attach the complete engine on its rubbers. Check the crank cl dimensions, front and rear to a flat ground surface. Let it sit there for a while, and check again.

Any sag will show up immediately. Should it sag just sitting there, it will certainly sag in operation.

Thx

[Skippydiesel]

Don’t guess- make sure!
........................................................
Any sag will show up immediately. Should it sag just sitting there, it will certainly sag in operation.

Thx

The design of the latest Sonex /Rotax engine mounts would suggest that "sag" is unlike.

My concerned is the engines lateral/rotational movement, that is likely to be most pronounced at start up & shut down, & the clearance, to inside of cowling, to accommodate this movement.

From the few responses received, it would seem that 10mm (about 3/8ths of an inch) is a generous allowance for front "rocker box" clearance and fuel pump - a little more (?) may be required at the exhaust tail pipe.

Prop spinner clearance looks like it could be reduced to 5mm (1/4 in)

Because my cooling system requires that as much air as possible exits via the coolant radiator, my exhaust pipe will have a flexible seal around its cowling exit. I will design the seal so as to allow for any increased movement in this area.

[13brv3]

I'm one step closer to being in the "actual flying" category. My Onex now has an airworthiness certificate now :-) The 912UL engine has been running really well on the ground, and I had it flying in another plane previously. The untested cooling configuration will be the only engine related concern, assuming you don't count keeping the prop from hitting the runway. I'm not in any hurry to fly it, and have a few other things to tinker with. Maybe in 2-3 weeks when it warms up a bit more.

Rusty

[13brv3]

It's official. Onex 085 made it's first flight today with a Rotax 912UL and Warp Drive 3 blade 60" prop. It was only about 20 min, just enough to do a few laps at 4000 ft, with a stall, then a landing. No significant issues. The engine was excellent, with nothing out of limits for cooling (purely amazing). Biggest issue is the prop is underpitched, which is an easy fix. There were a few other minor squawks to address with radio and Dynon settings, but overall it went as well as I could have hoped for. This was first flight #7 for me, and it never gets old.

Rusty

[Zack]

Congratulations!

[aschlem77]

Great work,

[CaseyCooper]

So awesome! Congratulations. I’m sure it was a wonderful feeling. I’d love to see pictures, video, and any performance figures you have! I hope you start racking up those hours!

[13brv3]

Everything is so temporary right now, I'd hate to post pictures of the cowling. I have a history of ugly cowls that haunts me even years later :-) The engine pics are already in the thread.

I had a gopro in the cockpit, but you can't read the instruments, which makes the flight really boring. About the only thing you can see is how far the ball is off center :-) My biggest issue is that my Dynon D-180 is intermittently dropping out on the EMS side. RPM goes to zero, and every other measurement just freezes. That's putting a damper on my performance data and I'm not sure how long it will take to get that fixed. Waiting to hear from Dynon, but between that, and weather the next week or so, I won't be racking up any hours. No hurry really though.

Thanks,
Rusty