Rotax RPMs

I'm reading the specs for the Remos G-3. Looks like a nice plane. But
one thing that gobsmacked me was the note that "Max endurance: 6hrs at
4300rpm". Does it really run at 4300rpm? Is the prop geared down from
that? I mean, I normally fly a Lance with a 300hp IO-540, and it's pretty
damn noisy at 2650 rpm. I shudder to think what a prop spinning at 4300
rpm sounds like.

--
Paul Tomblin http://blog.xcski.com/
"All life is transitory. A dream. We all come together in the same place at
the end of time. If I don't see you again here, I will see you in a little
while in the place where no shadows fall." - Delenn

Paul Tomblin wrote:
I'm reading the specs for the Remos G-3. Looks like a nice plane. But
one thing that gobsmacked me was the note that "Max endurance: 6hrs at
4300rpm". Does it really run at 4300rpm? Is the prop geared down from
that? I mean, I normally fly a Lance with a 300hp IO-540, and it's pretty
damn noisy at 2650 rpm. I shudder to think what a prop spinning at 4300
rpm sounds like.

I believe all Rotax 912's have a prop
gear reduction, with ratios of 2:1,
2.24:1 and 2.58:1 available. I couldn't
see any specs for what the G-3 comes
with, but would bet it was either the
2.24 or 2.58.

Paul Tomblin wrote:
I'm reading the specs for the Remos G-3. Looks like a nice plane.
But one thing that gobsmacked me was the note that "Max endurance:
6hrs at 4300rpm". Does it really run at 4300rpm?

Yes and yes.

A quick Google search yielded this info on the engine used in the
Remos:

http://www.rotaxservice.com/rotax_en...ax_912ULSs.htm

In a previous article, said:
A quick Google search yielded this info on the engine used in the
Remos:

http://www.rotaxservice.com/rotax_en...ax_912ULSs.htm

Ok, I'm a little embarassed that I couldn't find that info myself.

Is a reduction gearbox seen as a reliability problem, or isn't that such a
big deal any more?

--
Paul Tomblin http://blog.xcski.com/
"Oh my G'Quan, they killed Koshi!" - Citizen G'kyle, Babylon Park

"Paul Tomblin" wrote in message
...
In a previous article, said:
A quick Google search yielded this info on the engine used in the
Remos:

http://www.rotaxservice.com/rotax_en...ax_912ULSs.htm

Ok, I'm a little embarassed that I couldn't find that info myself.

Is a reduction gearbox seen as a reliability problem, or isn't that such a
big deal any more?

--


I haven't flown one, so I can't be certain, but I'm guessing it would at
least seriously hamper the engines ability to windmill during a temporary
fuel starvation, or carb ice situation.

On Nov 29, 3:47 pm, (Paul Tomblin) wrote:
In a previous article, said:

A quick Google search yielded this info on the engine used in the
Remos:

http://www.rotaxservice.com/rotax_en...ax_912ULSs.htm

Ok, I'm a little embarassed that I couldn't find that info myself.

Is a reduction gearbox seen as a reliability problem, or isn't that such a
big deal any more?

--
Paul Tomblin http://blog.xcski.com/
"Oh my G'Quan, they killed Koshi!" - Citizen G'kyle, Babylon Park

I don't think anyone really knows the reliability of this engine and
gearbox. It hasn't been in service long enough. I have been training
behind one in a Flight Design CT, and it is not a noisy engine at
all. When I watch a CT take off I am really struck by how quiet the
airplane is. Also the engine has altitude-compensating carbs, so
there is no mixture to mess with. In flight the engine is very
responsive and smooth. I know a lot of people are put off by the high
rpms, but if the engine is designed to run at those speeds I am not
sure that is really a problem.

My one comment on the gearbox is it has a harmonic resonance vibration
at about 1800-1900 rpm (taxi speeds) which is very noticeable. I try
to avoid that, and bump it up to about 2000, and it's nice and smooth
there.

Phil

Phil wrote in
:

On Nov 29, 3:47 pm, (Paul Tomblin) wrote:
In a previous article, said:

A quick Google search yielded this info on the engine used in the
Remos:

http://www.rotaxservice.com/rotax_en...ax_912ULSs.htm

Ok, I'm a little embarassed that I couldn't find that info myself.

Is a reduction gearbox seen as a reliability problem, or isn't that
such a big deal any more?

--
Paul Tomblin http://blog.xcski.com/
"Oh my G'Quan, they killed Koshi!" - Citizen G'kyle, Babylon Park

I don't think anyone really knows the reliability of this engine and
gearbox. It hasn't been in service long enough.

It's been around almost twenty years now!


Bertie

Phil wrote:
On Nov 29, 3:47 pm, (Paul Tomblin) wrote:
In a previous article, said:

A quick Google search yielded this info on the engine used in the
Remos:
http://www.rotaxservice.com/rotax_en...ax_912ULSs.htm
Ok, I'm a little embarassed that I couldn't find that info myself.

Is a reduction gearbox seen as a reliability problem, or isn't that such a
big deal any more?

--
Paul Tomblin http://blog.xcski.com/
"Oh my G'Quan, they killed Koshi!" - Citizen G'kyle, Babylon Park

I don't think anyone really knows the reliability of this engine and
gearbox. It hasn't been in service long enough. I have been training
behind one in a Flight Design CT, and it is not a noisy engine at
all. When I watch a CT take off I am really struck by how quiet the
airplane is. Also the engine has altitude-compensating carbs, so
there is no mixture to mess with. In flight the engine is very
responsive and smooth. I know a lot of people are put off by the high
rpms, but if the engine is designed to run at those speeds I am not
sure that is really a problem.

I'd like to get some more information on this.
The Rotax 912 has been in production since
around 1992 and the 912ULS since 1999. Should
be information somewhere.

I've heard that thousands of them have been
sold for drones and unmanned aircraft of various
types.

My one comment on the gearbox is it has a harmonic resonance vibration
at about 1800-1900 rpm (taxi speeds) which is very noticeable. I try
to avoid that, and bump it up to about 2000, and it's nice and smooth
there.

Yup. That's why there's a yellow band on
the tach. I try to never run my engine there.

Jim Stewart wrote in
:

Phil wrote:
On Nov 29, 3:47 pm, (Paul Tomblin) wrote:
In a previous article, said:

A quick Google search yielded this info on the engine used in the
Remos:
http://www.rotaxservice.com/rotax_en...ax_912ULSs.htm
Ok, I'm a little embarassed that I couldn't find that info myself.

Is a reduction gearbox seen as a reliability problem, or isn't that
such a big deal any more?

--
Paul Tomblin http://blog.xcski.com/
"Oh my G'Quan, they killed Koshi!" - Citizen G'kyle, Babylon Park

I don't think anyone really knows the reliability of this engine and
gearbox. It hasn't been in service long enough. I have been
training behind one in a Flight Design CT, and it is not a noisy
engine at all. When I watch a CT take off I am really struck by how
quiet the airplane is. Also the engine has altitude-compensating
carbs, so there is no mixture to mess with. In flight the engine is
very responsive and smooth. I know a lot of people are put off by
the high rpms, but if the engine is designed to run at those speeds I
am not sure that is really a problem.

I'd like to get some more information on this.
The Rotax 912 has been in production since
around 1992 and the 912ULS since 1999. Should
be information somewhere.

I've heard that thousands of them have been
sold for drones and unmanned aircraft of various
types.


There's been quite a lot of them on certified airplanes in Europe as
well as thousands on homebuilts round the world for quite some time.

It's pretty easy to check how well they work in the real world. Look for
airplanes for sale with the engine installed. If most of the airplanes
with around 1,000 hours on them have engines with about 500 hours on
them, well, you have your answer. But afaik, they work well and last a
long time.

Bertie