Rotax RPMs

"Kyle Boatright" wrote in
:


"Bertie the Bunyip" wrote in message
.. .
Phil wrote in
news:354adc88-de99-4b4d-bbc4-

:

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

Yeah, but other than that 20 year history, there is very little data.
;-)



There's loads of data..


Bertie

On Nov 29, 3:31 pm, "Maxwell" wrote:

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.

If a Lyc or Continental dies due to carb ice, it isn't going to
restart either. It needs air and fuel to generate heat to get the ice
out, and a pilot who lets things deteriorate until the thing is dead
is faced with a forced landing whether it's a direct-drive engine or a
geared engine.
Continental has built geared engines: The GO-300, GO-480, the
Tiara (not too successful), and there are many geared radials. Most
have some RPM range where they're not comfortable, and some direct-
drive setups have the same due to prop resonance. The Cherokee 180
was one of them. There's a yellow arc on the tach: pass through it,
don't linger there. All will be well.
Geared engines are more efficient in terms of weight/HP ratio.
HP is a function of torque times RPM, so raising RPM gets more jam for
a small weight increase in the form of a reduction of some sort.
Gears, V-belts, timing belts, chains; they've all been employed. In
some engines it improves safety by taking the thrust and gyroscopic
forces off the crankshaft and putting them onto something more
suitable.
If it hadn't been for geared engines we wouldn't have had the
P-51, P-40, Spitfire, P-38, Lancaster, and many more. On the other
hand, the other side wouldn't have been such a threat.

Dan

Matt Whiting schrieb:

Why do you want it to windmill? there is no vacuum system.

Quicker restart.

In the only situation that I can think of in which a quick engine
restart may matter, you really wouldn't want to dive for windmill.
Besides, using the starter yields the desired result at least as quickly.

wrote in
:

On Nov 29, 3:31 pm, "Maxwell" wrote:

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.

If a Lyc or Continental dies due to carb ice, it isn't going to
restart either. It needs air and fuel to generate heat to get the ice
out, and a pilot who lets things deteriorate until the thing is dead
is faced with a forced landing whether it's a direct-drive engine or a
geared engine.
Continental has built geared engines: The GO-300, GO-480, the
Tiara (not too successful), and there are many geared radials. Most
have some RPM range where they're not comfortable, and some direct-
drive setups have the same due to prop resonance. The Cherokee 180
was one of them. There's a yellow arc on the tach: pass through it,
don't linger there. All will be well.
Geared engines are more efficient in terms of weight/HP ratio.
HP is a function of torque times RPM, so raising RPM gets more jam for
a small weight increase in the form of a reduction of some sort.
Gears, V-belts, timing belts, chains; they've all been employed. In
some engines it improves safety by taking the thrust and gyroscopic
forces off the crankshaft and putting them onto something more
suitable.
If it hadn't been for geared engines we wouldn't have had the
P-51, P-40, Spitfire, P-38, Lancaster, and many more. On the other
hand, the other side wouldn't have been such a threat.

Dan

Again, it goes back much further than that. Hisso had a lot of success with
their geared version of the 8VA back in '17...

Bertie

On Nov 30, 9:34 am, Thomas Borchert
wrote:
Phil,

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

Are you kidding? These have been in service in huge numbers for well
over a decade. The original Diamond Katana was introduced with them.
These engines are VERY proven. It may have happened outside the US (and
thus outside the advertising range of "Flying" and thus outside their
editorial coverage), but trust me, it still happened.

--
Thomas Borchert (EDDH)

I thought the 912 was fairly new. I can't find a history of the
engine. Anybody know when they first came out?

Phil

Phil wrote in news:e2b63a34-2301-48d0-a78b-
:

On Nov 30, 9:34 am, Thomas Borchert
wrote:
Phil,

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

Are you kidding? These have been in service in huge numbers for well
over a decade. The original Diamond Katana was introduced with them.
These engines are VERY proven. It may have happened outside the US (and
thus outside the advertising range of "Flying" and thus outside their
editorial coverage), but trust me, it still happened.

--
Thomas Borchert (EDDH)

I thought the 912 was fairly new. I can't find a history of the
engine. Anybody know when they first came out?


1987. They gained certification in 1989


Bertie

Thomas Borchert wrote:
Paul,

Does it really run at 4300rpm?


Yes (no offense, but in what hole have you been hiding all those years?
;-))

It is geared down. It is a very, very quiet engine, much quieter than
any Lycosaurus or TCM. Thanks to water cooling which also ends the
shock cooling debate. Welcome to 1990s technology.


Really?

http://www.zenoswarbirdvideos.com/P-51_Variants.html

Seems like water cooling has been around just a little longer than that.

Matt

"Stefan" wrote in message
...
Matt Whiting schrieb:

Why do you want it to windmill? there is no vacuum system.

Quicker restart.

In the only situation that I can think of in which a quick engine restart
may matter, you really wouldn't want to dive for windmill. Besides, using
the starter yields the desired result at least as quickly.

You don't need to dive on a direct drive, the engine continues to windmill
from the time it stalls. In Cessna's you have to slow to very near stall
speed to actually stop the prop. I would suspect the same for all the
Lycoming and Continental powered aircraft.

wrote in message
...

If a Lyc or Continental dies due to carb ice, it isn't going to
restart either. It needs air and fuel to generate heat to get the ice
out, and a pilot who lets things deteriorate until the thing is dead
is faced with a forced landing whether it's a direct-drive engine or a
geared engine.

Not true, been there and done it.

"Maxwell" wrote in message
...
I'm guessing it would at least seriously hamper the engines ability to windmill
during a temporary fuel starvation, or carb ice situation.

A windmilling propeller significantly increases your sink rate when your
engine stops making noise. Do you really want that? ...or would you rather
have more time to sort things out, and/or more landing options within gliding
range?

I know my choice!

Vaughn