Whats the deal with counter-rotating props?

interesting... but a diagram with thrust vectors and with and without
counterrotating propellors would add to the clarification for this poster
BT

"Michael Ware" wrote in message
. ..

"Dico" wrote in message
oups.com...
So with counter rotating props I won't have the plane want to go left?

Correct. Not when they are both running, anyway!

Or I'd really have to hammer down the right rudder? Even worse if one
engine quit, I could be screwed? And I'm guessing the critical engine
comes into play here. Although I'm not sure if the critical engine
means its the good one (its critical you keep it) or the bad one (its
critical if you lose it)....

check this out.

http://avstop.com/Technical/twins.htm

Remember, too, that with a twin (except for planes like a Cessna 337) the
engines are not on the centerline of the fuselage, they are offset a few
feet.


-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

Thanks for the link.

A very interesting read! I'm that much smarter now!

Another question... can you retro fit planes so that they have CR
props? What kind of cost/job is involved? I am guessing that you'd
need an engine that turns the other way and a different prop... but i'm
sure there is a lot more to it.

-dr

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".

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

Thanks!

I will check out those sites!

-Dico

You would have to find if there is an STC to change an aircraft without CR
to CR
It involves more than just swapping the engine and propeller, also the
"rigging", and testing for the new MCA that the STC owner would have
completed and submitted to the FAA for certification.
BT

"Dico" wrote in message
oups.com...
Thanks for the link.

A very interesting read! I'm that much smarter now!

Another question... can you retro fit planes so that they have CR
props? What kind of cost/job is involved? I am guessing that you'd
need an engine that turns the other way and a different prop... but i'm
sure there is a lot more to it.

-dr

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

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