Whats the deal with counter-rotating props?

think of the thrust line of the propeller
and for the smart guy that mentioned right foot for take off.. that's some
thrust but also P-factor

without counter rotating propellers,
consider downward arc of prop has more thrust, left engine, downward prop is
next to fuselage, right engine it is on the right side of that engine and
farther from fuselage, if the left (critical) engine fails then all that
thrust is way out on the right side moment arm causing yaw, and if real
slow, roll factors to deal with.

counter rotating propeller means the right engine the propeller rotates
counter clockwise, moving that thrust line closer to the fuselage, (now same
on both sides) and reduces the yaw action in the event of either engine
failing.. thus negating the "critical engine" factor.

You need to pick up and read a good multi engine training manual.. something
by Kershner

BT

"Dico" wrote in message
oups.com...
Hello,

We're looking into a twin and the Twin Comanche is on our list. I know
that the later models have the counter rotating props -- although i
don't know too much about what this means, other than its "better".

We fly a mooney now and thus I don't worry about the prop -- as long as
it keeps spinning.

Is there a web site that gives a good explanation as to why I want CR
props. There are hundreds of the earlier model Twin Comanches flying
without the CR props --- so what does someone with 300 hours single
engine time need to worry about? What actually goes wrong? And when
it does, what happens? I hear "critical engine" but it means very
little to me.

I like to fly and try to be very careful when I do fly... but I don't
follow too much aviation stuff other than how it affects me -- so I'm
not exactly a "buff", hence the above questions which may seem obvious
to many.

Why are we looking at a Twin Comanche? Because its a twin, safer for
IFR flight (perhaps this is only preceived), plus we live on the east
coast on an island so we're flying over water quite a bit. Also this
plane has decent speed and is an "economical" twin. We rarely fly with
4 people, so we don't need any more seats than 4.

Any help or links to help would be appreciated.

Thanks,

Dico

What would you multi folks recommend as good "introductory" reading for
people considering moving up to a twin? Is there a book with a good
discussion of the issues pro and con on moving from a single to a twin?

Rob


"BTIZ" wrote in
news:CXXCf.53524$V.31153@fed1read04:

...
You need to pick up and read a good multi engine training manual..
something by Kershner

BT

One of my favorites is Bob Gardner's book The Complete Multi-Engine Pilot.
It's written in a very easy to read down to earth manner. The Jeppesen
Guided Flight Discovery, Multi Engine book is very complete, but in my
opinion hard to read due to the distracting pictures and captions.
Jim


Rob McDonald" wrote in message
...
What would you multi folks recommend as good "introductory" reading for
people considering moving up to a twin? Is there a book with a good
discussion of the issues pro and con on moving from a single to a twin?

Rob


"BTIZ" wrote in
news:CXXCf.53524$V.31153@fed1read04:

...
You need to pick up and read a good multi engine training manual..
something by Kershner

BT

Thanks Jim

"Jim Burns" wrote in
:

One of my favorites is Bob Gardner's book The Complete Multi-Engine
Pilot. It's written in a very easy to read down to earth manner. The
Jeppesen Guided Flight Discovery, Multi Engine book is very complete,
but in my opinion hard to read due to the distracting pictures and
captions. Jim


Rob McDonald" wrote in message
...
What would you multi folks recommend as good "introductory" reading...

If you are really considering a Twin Comanche, the best places for
answers to your questions are the International Comanche Society
(comancheflyer.com) and the Comanche Owners' Forum in the motor
transport section at delphiforums.com. There is a world of information
regarding Comanches at both of those sites.

Hank
Henry A. Spellman
Comanche N5903P

Dico wrote:
Hello,

We're looking into a twin and the Twin Comanche is on our list. I know
that the later models have the counter rotating props -- although i
don't know too much about what this means, other than its "better".

Thanks!

I will check out those sites!

-Dico

I didn't notice anyone bring this up in the thread. The AOPA published some
interesting stuff on the Twin Commanche without CR props since they were
giving one away last year. With the older style twin, if you slow it down
too much with the engines still developing thrust, it can flip over on its
back. One of the wings is effectively flying at a couple of degrees higher
angle of attach due to the prop airflow. I think this is the main reason
the newer Twin Comanches went to CR props.

--
Mike Noel,
Tucson, Arizona

'Men never do evil so completely and cheerfully as when they do it from
religious conviction.'

-Blaise Pascal
"Dico" wrote in message
oups.com...
Hello,

We're looking into a twin and the Twin Comanche is on our list. I know
that the later models have the counter rotating props -- although i
don't know too much about what this means, other than its "better".

We fly a mooney now and thus I don't worry about the prop -- as long as
it keeps spinning.

Is there a web site that gives a good explanation as to why I want CR
props. There are hundreds of the earlier model Twin Comanches flying
without the CR props --- so what does someone with 300 hours single
engine time need to worry about? What actually goes wrong? And when
it does, what happens? I hear "critical engine" but it means very
little to me.

I like to fly and try to be very careful when I do fly... but I don't
follow too much aviation stuff other than how it affects me -- so I'm
not exactly a "buff", hence the above questions which may seem obvious
to many.

Why are we looking at a Twin Comanche? Because its a twin, safer for
IFR flight (perhaps this is only preceived), plus we live on the east
coast on an island so we're flying over water quite a bit. Also this
plane has decent speed and is an "economical" twin. We rarely fly with
4 people, so we don't need any more seats than 4.

Any help or links to help would be appreciated.

Thanks,

Dico

Mike,
Doesn't that happen in any non-counter-rotating and
non-centerline-thrust twin when you try to operate below Vmc/se? It's
been a few years, so I have to ask: do they still require a Vmc/se
demonstration for the multi ticket?


-----Original Message-----
From: Mike Noel ]
Posted At: Sunday, January 29, 2006 3:05 PM
Posted To: rec.aviation.owning
Conversation: Whats the deal with counter-rotating props?
Subject: Whats the deal with counter-rotating props?

I didn't notice anyone bring this up in the thread. The AOPA
published
some
interesting stuff on the Twin Commanche without CR props since they
were
giving one away last year. With the older style twin, if you slow it
down
too much with the engines still developing thrust, it can flip over on
its
back. One of the wings is effectively flying at a couple of degrees
higher
angle of attach due to the prop airflow. I think this is the main
reason
the newer Twin Comanches went to CR props.

--
Mike Noel,
Tucson, Arizona

'Men never do evil so completely and cheerfully as when they do it
from
religious conviction.'

-Blaise Pascal
"Dico" wrote in message
oups.com...
Hello,

We're looking into a twin and the Twin Comanche is on our list. I
know
that the later models have the counter rotating props -- although i
don't know too much about what this means, other than its "better".

We fly a mooney now and thus I don't worry about the prop -- as long
as
it keeps spinning.

Is there a web site that gives a good explanation as to why I want
CR
props. There are hundreds of the earlier model Twin Comanches
flying
without the CR props --- so what does someone with 300 hours single
engine time need to worry about? What actually goes wrong? And
when
it does, what happens? I hear "critical engine" but it means very
little to me.

I like to fly and try to be very careful when I do fly... but I
don't
follow too much aviation stuff other than how it affects me -- so
I'm
not exactly a "buff", hence the above questions which may seem
obvious
to many.

Why are we looking at a Twin Comanche? Because its a twin, safer
for
IFR flight (perhaps this is only preceived), plus we live on the
east
coast on an island so we're flying over water quite a bit. Also
this
plane has decent speed and is an "economical" twin. We rarely fly
with
4 people, so we don't need any more seats than 4.

Any help or links to help would be appreciated.

Thanks,

Dico

it can happen in any twin, non centerline thrust with or without CR props
it just depends on the severity and size of the rudder needed to control

yes, Vmc/se is still required on the check ride
BT

"Jim Carter" wrote in message
et...
Mike,
Doesn't that happen in any non-counter-rotating and
non-centerline-thrust twin when you try to operate below Vmc/se? It's
been a few years, so I have to ask: do they still require a Vmc/se
demonstration for the multi ticket?


-----Original Message-----
From: Mike Noel ]
Posted At: Sunday, January 29, 2006 3:05 PM
Posted To: rec.aviation.owning
Conversation: Whats the deal with counter-rotating props?
Subject: Whats the deal with counter-rotating props?

I didn't notice anyone bring this up in the thread. The AOPA
published
some
interesting stuff on the Twin Commanche without CR props since they
were
giving one away last year. With the older style twin, if you slow it
down
too much with the engines still developing thrust, it can flip over on
its
back. One of the wings is effectively flying at a couple of degrees
higher
angle of attach due to the prop airflow. I think this is the main
reason
the newer Twin Comanches went to CR props.

--
Mike Noel,
Tucson, Arizona

'Men never do evil so completely and cheerfully as when they do it
from
religious conviction.'

-Blaise Pascal
"Dico" wrote in message
oups.com...
Hello,

We're looking into a twin and the Twin Comanche is on our list. I
know
that the later models have the counter rotating props -- although i
don't know too much about what this means, other than its "better".

We fly a mooney now and thus I don't worry about the prop -- as long
as
it keeps spinning.

Is there a web site that gives a good explanation as to why I want
CR
props. There are hundreds of the earlier model Twin Comanches
flying
without the CR props --- so what does someone with 300 hours single
engine time need to worry about? What actually goes wrong? And
when
it does, what happens? I hear "critical engine" but it means very
little to me.

I like to fly and try to be very careful when I do fly... but I
don't
follow too much aviation stuff other than how it affects me -- so
I'm
not exactly a "buff", hence the above questions which may seem
obvious
to many.

Why are we looking at a Twin Comanche? Because its a twin, safer
for
IFR flight (perhaps this is only preceived), plus we live on the
east
coast on an island so we're flying over water quite a bit. Also
this
plane has decent speed and is an "economical" twin. We rarely fly
with
4 people, so we don't need any more seats than 4.

Any help or links to help would be appreciated.

Thanks,

Dico

What's the deal with counter-rotating props? I mean they're props,
don't they all rotate? And what's up with this counter stuff. Who's
counting, why is everyong always trying to count everything.

(Sorry, couldn't help but hear Jerry Senfield in there somewhere).

-Robert