Propellors vs Rotors

snipped in places...
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Wilbur and Orville used the largest props that would fit on their
airframe. In 1903 those were 8' 6" each and turned between 300 and 350
rpm depending on how hot the engine was. At an average of 8.56hp (the
engine only made 11.78hp for a few seconds dead cold), the twin props
produced an average of 96 lbs of thrust. or 11.22 lbs of thrust per hp.
Not bad on the first try.

96 pounds of thrust from 11 horse?

Actually from the 8+ horsepower. Based on 1 horsepower = 1 pound of thrust
at 315 knots, the figure sounds like a reasonable static thrust value. The
thrust may have been a little less in flight.

What did that whole rig weigh?


I vaguely remember reading something like 600 pounds, plus the pilot of
course. Orville and Wilbur were both small and slight, so the gross weight
was probably only a little more than 700 pounds...

At any temperature above absolute zero there will be movement, or
"vibration" of the fluid molecules.

Does that mean the airplane will quit flying at absolute zero?

Colin

Peter Dohm wrote:

snipped in places...

--------------and snipped some more-----------

Wilbur and Orville used the largest props that would fit on their
airframe. In 1903 those were 8' 6" each and turned between 300 and 350
rpm depending on how hot the engine was. At an average of 8.56hp (the
engine only made 11.78hp for a few seconds dead cold), the twin props
produced an average of 96 lbs of thrust. or 11.22 lbs of thrust per hp.
Not bad on the first try.

96 pounds of thrust from 11 horse?


Actually from the 8+ horsepower. Based on 1 horsepower = 1 pound of thrust
at 315 knots, the figure sounds like a reasonable static thrust value. The
thrust may have been a little less in flight.


What did that whole rig weigh?



I vaguely remember reading something like 600 pounds, plus the pilot of
course. Orville and Wilbur were both small and slight, so the gross weight
was probably only a little more than 700 pounds...



700 lbs / 96 thrust = .137 - which is a wee bit below the .20 rule of thumb.

Might consider catapult launch?

"Richard Lamb" wrote in message
link.net...
Peter Dohm wrote:

snipped in places...

--------------and snipped some more-----------

Wilbur and Orville used the largest props that would fit on their
airframe. In 1903 those were 8' 6" each and turned between 300 and 350
rpm depending on how hot the engine was. At an average of 8.56hp (the
engine only made 11.78hp for a few seconds dead cold), the twin props
produced an average of 96 lbs of thrust. or 11.22 lbs of thrust per hp.
Not bad on the first try.

96 pounds of thrust from 11 horse?


Actually from the 8+ horsepower. Based on 1 horsepower = 1 pound of
thrust
at 315 knots, the figure sounds like a reasonable static thrust value.
The
thrust may have been a little less in flight.


What did that whole rig weigh?



I vaguely remember reading something like 600 pounds, plus the pilot of
course. Orville and Wilbur were both small and slight, so the gross
weight
was probably only a little more than 700 pounds...



700 lbs / 96 thrust = .137 - which is a wee bit below the .20 rule of
thumb.

Might consider catapult launch?


In a way, they almost did--sending it down a greased slide....

Remember that they had nearly 12 HP when first started--which gave them a
decent start slightly down hill and into the wind. All in all, I agree that
the whole enterprise was a little crazy. I am glad they succeeded, and
further engine development must have followed quickly.

Some of you will remember this photo from Flying Magazine
years ago:

http://www.grc.nasa.gov/WWW/K-12/air.../downplane.gif

There's definitely something going on behind that airplane.
The vortices are clearly visible, and the downwash trench is plenty
deep. There's debate as to whether that trench is due to vortex action,
or if the vortices are a result of the downwash. In any case, lots of
air has been displaced, and if Newton was right, there has to have been
some sort of reaction.
The air flowing off a trailing edge is angled down slightly
with respect to the airplane's flight path. The layer over the wing has
more speed and therefore more net energy, and its momentum carries both
it and the lower layer downward.
Aircraft, both fixed and rotary winged, have been used to
prevent frost in orchards on clear nights by flying low over them to
drive down the warmer air above them.

Dan

In article ,
T o d d P a t t i s t wrote:

..

There is one thing going on in this photo that should be
acknowledged, no matter how you view it. The jet has
significant nose up and has its engines pointed somewhat
down. There is some contribution to the downward airflow
from the thrust produced by those engines.


How do you know the plane is nose up if you don't know from where the
picture was taken? Personally, I can't tell much about the plane's
attitude in relation to the earth, its path relative to the clouds (i.e.
above or through,) nor its distance from the clouds at the moment of the
photo.

Smitty Two wrote:
In article ,
T o d d P a t t i s t wrote:

.

There is one thing going on in this photo that should be
acknowledged, no matter how you view it. The jet has
significant nose up and has its engines pointed somewhat
down. There is some contribution to the downward airflow
from the thrust produced by those engines.



How do you know the plane is nose up if you don't know from where the
picture was taken?

By looking at it!

If that's a real photo, this aircraft has got some deck angle...

In article .net,
Richard Lamb wrote:

Smitty Two wrote:


How do you know the plane is nose up if you don't know from where the
picture was taken?

By looking at it!

If that's a real photo, this aircraft has got some deck angle...

Fer christ's sake, not necessarily so, if the camera was at a lower
altitude than the subject plane. I, personally, do not know where the
camera was in relation to the subject, so I, personally, have *no idea*
what the plane's attitude was. And if you don't know where the camera
was, neither do you.

On Tue, 14 Mar 2006 22:26:39 -0800, Smitty Two
wrote:

In article .net,
Richard Lamb wrote:

Smitty Two wrote:


How do you know the plane is nose up if you don't know from where the
picture was taken?

By looking at it!

If that's a real photo, this aircraft has got some deck angle...

Fer christ's sake, not necessarily so, if the camera was at a lower
altitude than the subject plane. I, personally, do not know where the
camera was in relation to the subject, so I, personally, have *no idea*
what the plane's attitude was. And if you don't know where the camera
was, neither do you.


Well, if I remember training correctly, a plane that appears below the
horizon is at a lower altitude. This one is definitely below the
horizon. The angle of attack relative to the camera is about zero. I
believe the plane sliced the top of the cloud and is climbing toward
the camera plane. Climbing=increased deck angle?

Andy Asberry wrote:
On Tue, 14 Mar 2006 22:26:39 -0800, Smitty Two
wrote:


In article .net,
Richard Lamb wrote:


Smitty Two wrote:

How do you know the plane is nose up if you don't know from where the
picture was taken?

By looking at it!

If that's a real photo, this aircraft has got some deck angle...

Fer christ's sake, not necessarily so, if the camera was at a lower
altitude than the subject plane. I, personally, do not know where the
camera was in relation to the subject, so I, personally, have *no idea*
what the plane's attitude was. And if you don't know where the camera
was, neither do you.



Well, if I remember training correctly, a plane that appears below the
horizon is at a lower altitude. This one is definitely below the
horizon. The angle of attack relative to the camera is about zero. I
believe the plane sliced the top of the cloud and is climbing toward
the camera plane. Climbing=increased deck angle?

Thought I saw some of the bottom of that wing!