Light twins not using contra-rotating propellers

Mark Levin writes:

As was pointed out to me the Beechcraft Baron does not use contra-rotating
propellers. A bit of research showed me that most U.S. built light twins do
not use them either.

My question is why?

My guess is that the market for mirror-image engines (the most
straightforward implementation) is too small. If you don't use mirror
images, you have asymmetries in the powerplant engineering.

I do wish that things were different. I consider the effects of
P-factor and torque to be design defects.

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Recently, Mxsmanic posted:

Mark Levin writes:

As was pointed out to me the Beechcraft Baron does not use
contra-rotating propellers. A bit of research showed me that most
U.S. built light twins do not use them either.

My question is why?

My guess is that the market for mirror-image engines (the most
straightforward implementation) is too small. If you don't use mirror
images, you have asymmetries in the powerplant engineering.

Probably not the market, but the cost of maintenance, quantity of
available parts, and other things mentioned in this thread are reason
enough to warrant the practice.

I do wish that things were different. I consider the effects of
P-factor and torque to be design defects.

A design defect is a problem caused by some aspect of the design. I don't
know why you would consider the effects of propeller propulsion to be
"design defects". They are simply aspects of that type of propulsion.

Neil

Neil Gould writes:

A design defect is a problem caused by some aspect of the design. I don't
know why you would consider the effects of propeller propulsion to be
"design defects". They are simply aspects of that type of propulsion.

An aspect of propulsion that constantly pulls the aircraft to one side
sounds like a defect to me.

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On Fri, 01 Dec 2006 07:40:00 +0100, Mxsmanic wrote:

Neil Gould writes:

A design defect is a problem caused by some aspect of the design. I don't
know why you would consider the effects of propeller propulsion to be
"design defects". They are simply aspects of that type of propulsion.

An aspect of propulsion that constantly pulls the aircraft to one side
sounds like a defect to me.

No more than the fact that you can't pull the nose of a General Aviation up to a
90 degree angle and keep climbing. Designers *can* build airplanes that will do
this, but the cost/benefit tradeoffs usually preclude it. Similarly, the
P-factor effect is accepted in some cases in order to minimize the production
cost. A design defect is something unexpected that becomes apparent AFTER the
aircraft flies, not something that is known and recognized while the plane is
still on the drawing board.

Ron Wanttaja

Recently, Mxsmanic posted:

Neil Gould writes:

A design defect is a problem caused by some aspect of the design. I
don't know why you would consider the effects of propeller
propulsion to be "design defects". They are simply aspects of that
type of propulsion.

An aspect of propulsion that constantly pulls the aircraft to one side
sounds like a defect to me.

It is a simple matter accounted for by Newtonian physics. Apparently, the
"designer" of that aspect of the real world doesn't see a problem with it,
as "real world version 2.0 has yet to be released, AFAIK. BTW, pilots of
propeller-driven aircraft don't see a problem with it either.

TANSTAAFL.

Neil

Neil Gould writes:

It is a simple matter accounted for by Newtonian physics. Apparently, the
"designer" of that aspect of the real world doesn't see a problem with it,
as "real world version 2.0 has yet to be released, AFAIK.

It is more likely that nobody wants to pay to fix it.

BTW, pilots of propeller-driven aircraft don't see a problem with it either.

So if they had a choice between two otherwise identical aircraft, with
identical prices, they'd just flip a coin to choose between the one
with P-factor and torque and the one without?

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Recently, Mxsmanic posted:

Neil Gould writes:

It is a simple matter accounted for by Newtonian physics.
Apparently, the "designer" of that aspect of the real world doesn't
see a problem with it, as "real world version 2.0 has yet to be
released, AFAIK.

It is more likely that nobody wants to pay to fix it.

Who (or what) is in the position to "fix" Real World 1.0 that couldn't
easily afford the cost?

BTW, pilots of propeller-driven aircraft don't see a problem with it
either.

So if they had a choice between two otherwise identical aircraft, with
identical prices, they'd just flip a coin to choose between the one
with P-factor and torque and the one without?

Sorry, I prefer the Real World, the one in which such choices are unlikely
and the market has chosen their preferences.

Neil

"Mxsmanic" wrote in message
...

So if they had a choice between two otherwise identical aircraft, with
identical prices, they'd just flip a coin to choose between the one
with P-factor and torque and the one without?


I'd take the "P" factor airplane. It helps in controlling the airplane in
certain circumstances.

Karl
"Curator" N185KG

"Mxsmanic" wrote in message
...
Neil Gould writes:

A design defect is a problem caused by some aspect of the design. I don't
know why you would consider the effects of propeller propulsion to be
"design defects". They are simply aspects of that type of propulsion.

An aspect of propulsion that constantly pulls the aircraft to one side
sounds like a defect to me.

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You could say the same thing about lift, it has a "defective" component
called drag. Why don't you simply design that out? Why would anyone deliver
a defective airplane that came with drag?

The answer, of course, is that we have all done what we could, with what we
have. All real world design is a result of compromises, we don't have a
registry where the drag can be turned off, the p-factor zeroed without other
side effects.

Al G

Al G writes:

You could say the same thing about lift, it has a "defective" component
called drag. Why don't you simply design that out?

Modern airfoils attempt to do exactly that, with varying amounts of
success.

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