props: tractor v pusher, q tip, ducted?

[Tony]

If one uses the Cessna 377 Skymaster as an example, it's pretty clear
a pusher prop is more efficient than one pulling. The data seems mixed
though on q tip props -- any leads as to where there may be quantative
data? What I found suggested the extra length of the prop might just
as well go to increasing its radius as in decreasing end vortix
effects. Finally, does anyone know of any work on small airplanes
using a ducted prop (shrouding it rather than using the q tip bent
end? I'm not worried about ease of flying (the problem with pusher
props are pretty obvious) but rather with converting the horsepower
delivered to the prop into usable thrust, that is, getting the
greatest efficiency (miles per gallon is a crude way of expressing it)
for a small single.

[Tony]

opps, should have said Cessna 337.

[Kingfish]

On Aug 5, 8:27 pm, Tony > wrote:
> If one uses the Cessna 377 Skymaster as an example, it's pretty clear
> a pusher prop is more efficient than one pulling.

It is? How do you figure, seeing as the 337 has a tractor AND a pusher
prop?

[Matt Whiting]

Kingfish wrote:
> On Aug 5, 8:27 pm, Tony > wrote:
>> If one uses the Cessna 377 Skymaster as an example, it's pretty clear
>> a pusher prop is more efficient than one pulling.
>
> It is? How do you figure, seeing as the 337 has a tractor AND a pusher
> prop?
>

I believe the performance is better flying on the rear engine alone vs.
the front alone.

Matt

[Kyle Boatright]

"Kingfish" > wrote in message
oups.com...
> On Aug 5, 8:27 pm, Tony > wrote:
>> If one uses the Cessna 377 Skymaster as an example, it's pretty clear
>> a pusher prop is more efficient than one pulling.
>
> It is? How do you figure, seeing as the 337 has a tractor AND a pusher
> prop?

The single engine climb performance is pitiful regardless of which engine is
caged, but the aircraft has more performance on the back engine than the
front. That may or may not be due to prop efficiency. It could also be due
to reduced fuselage drag. The tractor prop blows a high speed stream of air
across the fuselage, creating its own source of drag. This isn't as much of
a factor with the pusher.

KB

[Morgans[_2_]]

"Tony" > wrote in message
oups.com...
> If one uses the Cessna 377 Skymaster as an example, it's pretty clear
> a pusher prop is more efficient than one pulling. The data seems mixed
> though on q tip props -- any leads as to where there may be quantative
> data? What I found suggested the extra length of the prop might just
> as well go to increasing its radius as in decreasing end vortix
> effects. Finally, does anyone know of any work on small airplanes
> using a ducted prop (shrouding it rather than using the q tip bent
> end? I'm not worried about ease of flying (the problem with pusher
> props are pretty obvious) but rather with converting the horsepower
> delivered to the prop into usable thrust, that is, getting the
> greatest efficiency (miles per gallon is a crude way of expressing it)
> for a small single.
>

On the subject of shrouded props, yes studies have been done, but I did not
link to them, so do not know where to find them.

There are very few flying examples of shrouded light plane props. A shroud
is tough to justify, because of a couple reasons. Prop to shroud clearance
has to be VERY small, generally under 1/16", for any great improvement of
efficiency. Therein lies the rub.

Maintaining the close clearance is tough, because the shroud would have to
be very stiff, and strong, to not flex and hit the prop. That means weight.
That means it will have to increase efficiency a good deal, to justify
carrying the extra weight around.

Also, the shroud would have to be mounted to the engine mount, (more
complexity, more weight) or else the engine would have to be hard mounted.
That is because the soft mounts of the engine would allow the engine (and
prop disc) to move around (and most of them move around a LOT), and if the
shroud were mounted to the fuselage, you can imagine that there would not be
close prop clearance for very long. <g>

Also, there is also the subject of the shroud and that dreaded drag. Of
course, we don't want to add anything to our airplanes that stick out in the
wind that does not need to be there. A shroud and mounts is something, and
a pretty big something at that. So more drag means it will have to produce
even more efficiency.

Humm, it seems like we have now said that it has to increase efficiency a
couple times, and we have now used up all of the possible efficiency gains
just to balance the disadvantages.

What does it mean in the long run? We have a more complex, heavier
airplane, for no noticeable improvement in performance.

That's why you don't see many shrouded airplanes running around out there.
--
Jim in NC

[Bertie the Bunyip[_19_]]

Tony > wrote in news:1186363629.396826.234140
@k79g2000hse.googlegroups.com:

> If one uses the Cessna 377 Skymaster as an example, it's pretty clear
> a pusher prop is more efficient than one pulling.


No, it isn#t actually. After Cessna sorted out the cooling drag on the
front engine, the performance was identical on either engine. The legend
lives on though!


The data seems mixed
> though on q tip props -- any leads as to where there may be quantative
> data? What I found suggested the extra length of the prop might just
> as well go to increasing its radius as in decreasing end vortix
> effects.


I flew a few q tip mooneys as well as standard equipped airplanes. The q-
tip airplanes all performed worse.


Bertie

[john smith[_2_]]

In article . com>,
Tony > wrote:

> If one uses the Cessna 377 Skymaster as an example, it's pretty clear
> a pusher prop is more efficient than one pulling. The data seems mixed
> though on q tip props -- any leads as to where there may be quantative
> data? What I found suggested the extra length of the prop might just
> as well go to increasing its radius as in decreasing end vortix
> effects. Finally, does anyone know of any work on small airplanes
> using a ducted prop (shrouding it rather than using the q tip bent
> end? I'm not worried about ease of flying (the problem with pusher
> props are pretty obvious) but rather with converting the horsepower
> delivered to the prop into usable thrust, that is, getting the
> greatest efficiency (miles per gallon is a crude way of expressing it)
> for a small single.

Have you looked at the Edgley Optica?

[Danny Deger]

"Morgans" > wrote in message
...
>
snip

> There are very few flying examples of shrouded light plane props. A
> shroud is tough to justify, because of a couple reasons. Prop to shroud
> clearance has to be VERY small, generally under 1/16", for any great
> improvement of efficiency. Therein lies the rub.

Nice pun. I am proud of you :-)

Danny Deger

P.S. I liked the rest of you write-up.

[Tina]

The data I saw showed the 337 single engine pusher doing better, maybe
it is old data. The tractor prop is wasting energy blowing on the
windscreen and cowling, problems the pusher doesn't have. I know the
biggest gains the Mooney Exec had in going to the 201 had was because
of the cowling and windscreen redesign.

I never heard that q tips did worse than straight bladed props, that
was an interesting observation.

Aren't Lakers configured as pushers? That is an interesting example.
because the engine is just hanging out there, you could put the prop
on either end.

[Bertie the Bunyip[_19_]]

Tina > wrote in news:1186370891.595213.170320
@w3g2000hsg.googlegroups.com:

> The data I saw showed the 337 single engine pusher doing better, maybe
> it is old data. The tractor prop is wasting energy blowing on the
> windscreen and cowling, problems the pusher doesn't have. I know the
> biggest gains the Mooney Exec had in going to the 201 had was because
> of the cowling and windscreen redesign.
>

That's for the early airplanes regarding the Skymasters. the loss was in
cooling drag, which Cessna improved. After that the SE ceiling cruise
and climb were virtually identical, but the reputation the rear engine
had for better SE performance never went away..

> I never heard that q tips did worse than straight bladed props, that
> was an interesting observation.
>

Actaully, it was more than an observation. the Q tips were installed as
a noise requirement for Swiss registered airplanes. These airplanes had
a supplememt to the POH with degraded performance. Having said that they
also had "Swiss Mufflers" but they're supposed to have no effect on
performance.
Also flew a couple of Arrows similarly equipped as well as a Cessna 182
RG. Same deal for all of them IIRC. Some were German and I seem to
remember they had a different muffler assembly in Germany which deliverd
worse performance and made more noise.


> Aren't Lakers configured as pushers? That is an interesting example.
> because the engine is just hanging out there, you could put the prop
> on either end.
>
>
Well, you're getting down to comparing apples with oranges. You'd have
to take two essentially identical aircraft and try both configurations
with it for a satisfacory answer based solely on observed performance,
but in reality, a real world airplane is going to throw so many other
variables, such as cooliing requirements, planform due to CG
considerations, disc availability due to fuselage cross section, whoch,
of course is down to cabin space, mission requirements yadda yadda
yadda. At the end of the day, when you look at similarly powered
aircraft with similar missions, or even better, if you look at the Cafe
racers, the evidence says it's al down to how clever the designer is,
and there's not a lot in any configuration, pusher, tractor tandem wing,
canard or conventional...



Bertie

[BobHoover]

> > improvement of efficiency. Therein lies the rub.
>
> Nice pun. I am proud of you :-)
>
------------------------------------------------------------------------

As a point of interest the 4-place shrouded pusher developed by Ryan
after WWII had the tips in contact with a compliant gasket embedded in
the shroud.

The plane was an all-composite design, by the way. Interesting in the
engineering sense but over-weight and too expensive. They did the
test flights
at Holtville and there's still a few films of it.

-R.S.Hoover

[Charles Talleyrand]

On Aug 5, 11:46 pm, Bertie the Bunyip > wrote:

> That's for the early airplanes regarding the Skymasters. the loss was in
> cooling drag, which Cessna improved. After that the SE ceiling cruise
> and climb were virtually identical, but the reputation the rear engine
> had for better SE performance never went away..


How can that be? The engine cowling has the same openings wether the
engine is turning or not. In other words, whatever the drag of the
front engine cowling, it should be the same whether the engine is
turning or not.

I'm assuming that the propeller does not effect airflow tooooo much
near the root, where it spins slowly and has a less aerodynamic shape
than near the tip, where most thrust is generated.

[Montblack]

("john smith" wrote)
> Have you looked at the Edgley Optica?


Yup! <g>

http://www.midwaysailor2.com/blaine/optica.html
Discover Aviation Days (2003)

The event is now called (B)laine (A)viation (W)eekend


Paul-Mont
(2007) B.A.W. Event Chair for:
Parking / People (Our Volunteers) / Pop

[Bertie the Bunyip[_19_]]

Charles Talleyrand > wrote in
ups.com:

> On Aug 5, 11:46 pm, Bertie the Bunyip > wrote:
>
>> That's for the early airplanes regarding the Skymasters. the loss was
in
>> cooling drag, which Cessna improved. After that the SE ceiling cruise
>> and climb were virtually identical, but the reputation the rear
engine
>> had for better SE performance never went away..
>
>
> How can that be? The engine cowling has the same openings wether the
> engine is turning or not.

It doesn't
Same openings, different drag profile with the engines running.

In any case, it's a fact that the later Skymasters had virtually the
same performance with either engine out.


In other words, whatever the drag of the
> front engine cowling, it should be the same whether the engine is
> turning or not.


It isn't.

>
> I'm assuming that the propeller does not effect airflow tooooo much
> near the root, where it spins slowly and has a less aerodynamic shape
> than near the tip, where most thrust is generated.

The drag is induced by the cooling itself.


Bertie.

[Charles Talleyrand]

On Aug 7, 7:34 am, Bertie the Bunyip > wrote:


> The drag is induced by the cooling itself.

How can the drag be induced by the cooling itself? If I understand
you, the same cowling with the same air flow shows significantly
different drag depending on whether the engine inside is hot or cold.

I honestly don't understand that.

[Morgans[_2_]]

"Charles Talleyrand" > wrote in message
oups.com...
> On Aug 7, 7:34 am, Bertie the Bunyip > wrote:
>
>
>> The drag is induced by the cooling itself.
>
> How can the drag be induced by the cooling itself? If I understand
> you, the same cowling with the same air flow shows significantly
> different drag depending on whether the engine inside is hot or cold.
>
> I honestly don't understand that.

The air entering the engine compartment, and flowing past the running
engine's hot cooling fins expands at LEAST double.

That is why the exit opening is much larger than the intake.

That is why there have been claims that the P-51 has a positive cooling
drag, that is the heated air exiting actually gives more thrust than the
drag of air entering the radiator passage and going past the radiator.
--
Jim in NC

[Kyle Boatright]

"Morgans" > wrote in message
...
>
> "Charles Talleyrand" > wrote in message
> oups.com...
>> On Aug 7, 7:34 am, Bertie the Bunyip > wrote:
>>
>>
>>> The drag is induced by the cooling itself.
>>
>> How can the drag be induced by the cooling itself? If I understand
>> you, the same cowling with the same air flow shows significantly
>> different drag depending on whether the engine inside is hot or cold.
>>
>> I honestly don't understand that.
>
> The air entering the engine compartment, and flowing past the running
> engine's hot cooling fins expands at LEAST double.
>
> That is why the exit opening is much larger than the intake.
>
> That is why there have been claims that the P-51 has a positive cooling
> drag, that is the heated air exiting actually gives more thrust than the
> drag of air entering the radiator passage and going past the radiator.
> --
> Jim in NC

Double? Naah. It expands, but doesn't double. Boyle's law (PV=NRT) is
based on absolute temperature, which is measured in kelvin. Kelvin is
Celsius plus 273 degrees. Guessing now, if the air temp went from 300k to
350k (or about 80F/27C to about 160F/70C) you'd see volume increase by
(350/300 -1) = 1/6th = about 17%...

KB

[Bertie the Bunyip[_19_]]

Charles Talleyrand > wrote in
oups.com:

> On Aug 7, 7:34 am, Bertie the Bunyip > wrote:
>
>
>> The drag is induced by the cooling itself.
>
> How can the drag be induced by the cooling itself?


If I understand
> you, the same cowling with the same air flow shows significantly
> different drag depending on whether the engine inside is hot or cold.
>
> I honestly don't understand that.

Not what I mean. the flow inside is quite different with the prop
turning or not, though.

I'm away at the moment, but I'll look in my library when I get home for
a better definition than I can provide off the top of my head..K?

In any case, It's Cessna's claim nd not mine that cooling drag was
sorted on the airplane.

I also recently read an aricle in a very old Sport aviation about the
pros and cons of pusher/tractor arrangements. I can't remember if the
author came up with a definitive answer as to which was better or more
efficient, but I don#'t see how he could, really.



Bertie
>
>
>
>
>
>

[Bertie the Bunyip[_19_]]

"Kyle Boatright" > wrote in
:

>
> "Morgans" > wrote in message
> ...
>>
>> "Charles Talleyrand" > wrote in message
>> oups.com...
>>> On Aug 7, 7:34 am, Bertie the Bunyip > wrote:
>>>
>>>
>>>> The drag is induced by the cooling itself.
>>>
>>> How can the drag be induced by the cooling itself? If I understand
>>> you, the same cowling with the same air flow shows significantly
>>> different drag depending on whether the engine inside is hot or
>>> cold.
>>>
>>> I honestly don't understand that.
>>
>> The air entering the engine compartment, and flowing past the running
>> engine's hot cooling fins expands at LEAST double.
>>
>> That is why the exit opening is much larger than the intake.
>>
>> That is why there have been claims that the P-51 has a positive
>> cooling drag, that is the heated air exiting actually gives more
>> thrust than the drag of air entering the radiator passage and going
>> past the radiator. --
>> Jim in NC
>
> Double? Naah. It expands, but doesn't double. Boyle's law (PV=NRT)
> is based on absolute temperature, which is measured in kelvin. Kelvin
> is Celsius plus 273 degrees. Guessing now, if the air temp went from
> 300k to 350k (or about 80F/27C to about 160F/70C) you'd see volume
> increase by (350/300 -1) = 1/6th = about 17%...
>
> KB
>

It's certainly standard practice, at least on airplanes where min
cooling drag is desired, that the outlet be conderably larger than the
inlet...


Bertie
>
>

[Morgans[_2_]]

"Kyle Boatright" > wrote

> Double? Naah. It expands, but doesn't double. Boyle's law (PV=NRT) is
> based on absolute temperature, which is measured in kelvin. Kelvin is
> Celsius plus 273 degrees. Guessing now, if the air temp went from 300k to
> 350k (or about 80F/27C to about 160F/70C) you'd see volume increase by
> (350/300 -1) = 1/6th = about 17%...

OK. I have always heard the approximate rule for good cooling is double the
intake size for the exit size. Guess it doesn't transfer to expansion.
--
Jim in NC

[Danny Deger]

"Morgans" > wrote in message
...
>
> "Kyle Boatright" > wrote
>
>> Double? Naah. It expands, but doesn't double. Boyle's law (PV=NRT) is
>> based on absolute temperature, which is measured in kelvin. Kelvin is
>> Celsius plus 273 degrees. Guessing now, if the air temp went from 300k to
>> 350k (or about 80F/27C to about 160F/70C) you'd see volume increase by
>> (350/300 -1) = 1/6th = about 17%...
>
> OK. I have always heard the approximate rule for good cooling is double
> the intake size for the exit size. Guess it doesn't transfer to
> expansion.
> --

Maybe the velocity of the exit gasses are less. This would cause them to
need more area.

Danny Deger

[Jon Woellhaf]

Jim Morgans wrote

> OK. I have always heard the approximate rule for good cooling is double
> the intake size for the exit size. Guess it doesn't transfer to
> expansion.

Did you mean to write, "... double the exit size for the intake size?" If
not, you lost me.

[Morgans[_2_]]

"Jon Woellhaf" > wrote in message
...
> Jim Morgans wrote
>
>> OK. I have always heard the approximate rule for good cooling is double
>> the intake size for the exit size. Guess it doesn't transfer to
>> expansion.
>
> Did you mean to write, "... double the exit size for the intake size?" If
> not, you lost me.

Difficult to communicate that clearly, I guess. Try this.

If the cooling intake is 50 square inches, the exit for the cooling air is
100 square inches. For planes with moveable cowl openings, that would be
with the cowl open full.
--
Jim in NC

[Jon Woellhaf]

Doh! I get what you wrote now. Ain't English great. So easy to be almost
mostly not misunderstood. <g>

"Morgans" > wrote in message
...
>
> "Jon Woellhaf" > wrote in message
> ...
>> Jim Morgans wrote
>>
>>> OK. I have always heard the approximate rule for good cooling is double
>>> the intake size for the exit size. Guess it doesn't transfer to
>>> expansion.
>>
>> Did you mean to write, "... double the exit size for the intake size?" If
>> not, you lost me.
>
> Difficult to communicate that clearly, I guess. Try this.
>
> If the cooling intake is 50 square inches, the exit for the cooling air is
> 100 square inches. For planes with moveable cowl openings, that would be
> with the cowl open full.
> --
> Jim in NC
>

[Danny Deger]

"Morgans" > wrote in message
...
>
> "Kyle Boatright" > wrote
>
>> Double? Naah. It expands, but doesn't double. Boyle's law (PV=NRT) is
>> based on absolute temperature, which is measured in kelvin. Kelvin is
>> Celsius plus 273 degrees. Guessing now, if the air temp went from 300k to
>> 350k (or about 80F/27C to about 160F/70C) you'd see volume increase by
>> (350/300 -1) = 1/6th = about 17%...
>
> OK. I have always heard the approximate rule for good cooling is double
> the intake size for the exit size. Guess it doesn't transfer to
> expansion.

Thanks for the info on the air expanding. Does this translate into more
drag if the engine is running?

Danny Deger

[Montblack]

("Jon Woellhaf" wrote)
> Doh! I get what you wrote now. Ain't English great. So easy to be almost
> mostly not misunderstood. <g>

My niece spent a year in Denmark as a foreign exchange student ("Fez"). Her
classmates were learning French. The French teacher spoke no English. My
niece spoke little Danish and NO French. They both spoke Spanish. So..., she
had a year of French class, translated to/from Spanish, while attending
school in Denmark.


Paul-Mont

[Gig 601XL Builder]

Montblack wrote:
> ("Jon Woellhaf" wrote)
>> Doh! I get what you wrote now. Ain't English great. So easy to be
>> almost mostly not misunderstood. <g>
>
> My niece spent a year in Denmark as a foreign exchange student
> ("Fez"). Her classmates were learning French. The French teacher
> spoke no English. My niece spoke little Danish and NO French. They
> both spoke Spanish. So..., she had a year of French class, translated
> to/from Spanish, while attending school in Denmark.
>
>
> Paul-Mont

So what was the outcome? Does she speak French with a Spanish accent?

[Montblack]

("Gig 601XL Builder" wrote)
> So what was the outcome? Does she speak French with a Spanish accent?


She's got a couple of degrees in science (chemistry? physics? geology?) I
think. She spent some time in the field doing geological work with oil
drilling companies, then decided (at 29) to go back to school and get a law
degree - like her parents. So in the end, she's headed for a career of

(you guessed it) ... double-talk! <g>


Paul-Mont

[Kingfish]

On Aug 9, 10:47 am, "Montblack" <Y4_NOT!...
> wrote:

> She's got a couple of degrees in science (chemistry? physics? geology?) I
> think. She spent some time in the field doing geological work with oil
> drilling companies, then decided (at 29) to go back to school and get a law
> degree - like her parents. So in the end, she's headed for a career of
>
> (you guessed it) ... double-talk! <g>
>
> Paul-Mont

Ugh. If only I could reach you with this paintball gun - or grenade...
<G>

[Big John]

I flew the 0-2 in VN. Single engine performance, either front or rear,
was not very good. That being said, the rear engine gave better SE
performance. We were told in ground school that the rear prop sucked
air over the wing center section at a higher velocity and gave more
lift than the front engine could push it up and over the center of
wing.

No matter the reason, the bird flew better SE on rear engine. SE on
either engine, the machine turned into a donut making device or worse
if you were not careful.

Big John
****************************************888

On Sun, 5 Aug 2007 22:15:55 -0400, "Kyle Boatright"
> wrote:

>
>"Kingfish" > wrote in message
oups.com...
>> On Aug 5, 8:27 pm, Tony > wrote:
>>> If one uses the Cessna 377 Skymaster as an example, it's pretty clear
>>> a pusher prop is more efficient than one pulling.
>>
>> It is? How do you figure, seeing as the 337 has a tractor AND a pusher
>> prop?
>
>The single engine climb performance is pitiful regardless of which engine is
>caged, but the aircraft has more performance on the back engine than the
>front. That may or may not be due to prop efficiency. It could also be due
>to reduced fuselage drag. The tractor prop blows a high speed stream of air
>across the fuselage, creating its own source of drag. This isn't as much of
>a factor with the pusher.
>
>KB
>

[Tina]

I would have thought the gain for the rear engine was because the air
stream was not hitting the windscreen and losing energy that way. The
air coming into the prop comes from all directions (just flowing into
a low pressure area) but the stream leaving is directed.

But if in the newer Skymasters both engines give the same single
engine performance my idea has to be wrong






On Aug 9, 2:28 pm, Big John > wrote:
> I flew the 0-2 in VN. Single engine performance, either front or rear,
> was not very good. That being said, the rear engine gave better SE
> performance. We were told in ground school that the rear prop sucked
> air over the wing center section at a higher velocity and gave more
> lift than the front engine could push it up and over the center of
> wing.
>
> No matter the reason, the bird flew better SE on rear engine. SE on
> either engine, the machine turned into a donut making device or worse
> if you were not careful.
>
> Big John
> ****************************************888
>
> On Sun, 5 Aug 2007 22:15:55 -0400, "Kyle Boatright"
>
>
>
> > wrote:
>
> >"Kingfish" > wrote in message
> oups.com...
> >> On Aug 5, 8:27 pm, Tony > wrote:
> >>> If one uses the Cessna 377 Skymaster as an example, it's pretty clear
> >>> a pusher prop is more efficient than one pulling.
>
> >> It is? How do you figure, seeing as the 337 has a tractor AND a pusher
> >> prop?
>
> >The single engine climb performance is pitiful regardless of which engine is
> >caged, but the aircraft has more performance on the back engine than the
> >front. That may or may not be due to prop efficiency. It could also be due
> >to reduced fuselage drag. The tractor prop blows a high speed stream of air
> >across the fuselage, creating its own source of drag. This isn't as much of
> >a factor with the pusher.
>
> >KB- Hide quoted text -
>
> - Show quoted text -

[Big John]

Tina

I can only tell you what Air Force ground school said when checking us
out in 0-2. Know from experience that SE rear was better than SE front
engine. Not much, but better.

Big John
*********************************************

On Thu, 09 Aug 2007 16:36:56 -0700, Tina >
wrote:

>I would have thought the gain for the rear engine was because the air
>stream was not hitting the windscreen and losing energy that way. The
>air coming into the prop comes from all directions (just flowing into
>a low pressure area) but the stream leaving is directed.
>
>But if in the newer Skymasters both engines give the same single
>engine performance my idea has to be wrong
>
>
>
>
>
>
>On Aug 9, 2:28 pm, Big John > wrote:
>> I flew the 0-2 in VN. Single engine performance, either front or rear,
>> was not very good. That being said, the rear engine gave better SE
>> performance. We were told in ground school that the rear prop sucked
>> air over the wing center section at a higher velocity and gave more
>> lift than the front engine could push it up and over the center of
>> wing.
>>
>> No matter the reason, the bird flew better SE on rear engine. SE on
>> either engine, the machine turned into a donut making device or worse
>> if you were not careful.
>>
>> Big John
>> ****************************************888
>>
>> On Sun, 5 Aug 2007 22:15:55 -0400, "Kyle Boatright"
>>
>>
>>
>> > wrote:
>>
>> >"Kingfish" > wrote in message
>> oups.com...
>> >> On Aug 5, 8:27 pm, Tony > wrote:
>> >>> If one uses the Cessna 377 Skymaster as an example, it's pretty clear
>> >>> a pusher prop is more efficient than one pulling.
>>
>> >> It is? How do you figure, seeing as the 337 has a tractor AND a pusher
>> >> prop?
>>
>> >The single engine climb performance is pitiful regardless of which engine is
>> >caged, but the aircraft has more performance on the back engine than the
>> >front. That may or may not be due to prop efficiency. It could also be due
>> >to reduced fuselage drag. The tractor prop blows a high speed stream of air
>> >across the fuselage, creating its own source of drag. This isn't as much of
>> >a factor with the pusher.
>>
>> >KB- Hide quoted text -
>>
>> - Show quoted text -
>