Advancement of prop blade in flight, new information

Sorry, I got my information wrong when I stated that a three bladed
prop advanced 15 inches during each revolution at 200 mph.

I now have the article in front of me and the exact quote is as
follows: "At 200 mph and 2,800 rpm, the blades on my three-plade prop
follow three distinct helical paths through the air, and each blade is
25" ahead of the previous blade at the same point of rotation."

I repeat that I am not a prop engineer nor do I have any formal
training in aerodynamics but it appears to me that by advancing 25"
during it's revolution, the affect of one blade might have upon the
next one would seem to be pretty inconsequential.

Corky Scott

Sorry, I got my information wrong when I stated that a three bladed
prop advanced 15 inches during each revolution at 200 mph.

I now have the article in front of me and the exact quote is as
follows: "At 200 mph and 2,800 rpm, the blades on my three-plade prop
follow three distinct helical paths through the air, and each blade is
25" ahead of the previous blade at the same point of rotation."

I repeat that I am not a prop engineer nor do I have any formal
training in aerodynamics but it appears to me that by advancing 25"
during it's revolution, the affect of one blade might have upon the
next one would seem to be pretty inconsequential.

Corky Scott

For what it's worth, at 150 kts and 2500 RPM means the airplane advances about
6 feet per prop rev. A two bladed prop means each balde is in air 3 feet ahead
of the prior blade.

AJW wrote:

[snip]
For what it's worth, at 150 kts and 2500 RPM means the airplane advances about
6 feet per prop rev. A two bladed prop means each balde is in air 3 feet ahead
of the prior blade.

That's the same number I came up with, but that assumes there's a
one-to-one ratio between engine RPM and prop RPM. Is that true of all
single engine piston aircraft? I'm obviously not an AC mechanic, but I
thought I could see a reduction gear in the cowl.

DanH

AJW wrote:

[snip]
For what it's worth, at 150 kts and 2500 RPM means the airplane advances
about
6 feet per prop rev. A two bladed prop means each balde is in air 3 feet
ahead
of the prior blade.

That's the same number I came up with, but that assumes there's a
one-to-one ratio between engine RPM and prop RPM. Is that true of all
single engine piston aircraft? I'm obviously not an AC mechanic, but I
thought I could see a reduction gear in the cowl.

I don't know of a SEL airplane in general use that uses reduction gearing
between the shaft and the prop, Dan.

In article ,
emove (AJW) wrote:



I don't know of a SEL airplane in general use that uses reduction gearing
between the shaft and the prop, Dan.

Cessna 175

--
Dale L. Falk

There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.

http://home.gci.net/~sncdfalk/flying.html

Any airplane with a "G" in its engine designation.

Mike
MU-2

"AJW" wrote in message
...

AJW wrote:

[snip]
For what it's worth, at 150 kts and 2500 RPM means the airplane
advances
about
6 feet per prop rev. A two bladed prop means each balde is in air 3
feet
ahead
of the prior blade.

That's the same number I came up with, but that assumes there's a
one-to-one ratio between engine RPM and prop RPM. Is that true of all
single engine piston aircraft? I'm obviously not an AC mechanic, but I
thought I could see a reduction gear in the cowl.

I don't know of a SEL airplane in general use that uses reduction gearing
between the shaft and the prop, Dan.

Ajw,

I don't know of a SEL airplane in general use that uses reduction gearing
between the shaft and the prop, Dan.


All Thielert Centurion driven aircraft - way over 100 and counting.

--
Thomas Borchert (EDDH)

In article , AJW wrote:
I don't know of a SEL airplane in general use that uses reduction gearing
between the shaft and the prop, Dan.

Many hundreds of examples of Europa aircraft. My friend's Europa runs
the 4-cylinder, opposed, liquid cooled 914S engine at something like
5400RPM in cruise. I think the prop turns less than half that RPM.

--
Dylan Smith, Castletown, Isle of Man
Flying: http://www.dylansmith.net
Frontier Elite Universe: http://www.alioth.net
"Maintain thine airspeed, lest the ground come up and smite thee"

"Dylan Smith" wrote in message
...
In article , AJW
wrote:
I don't know of a SEL airplane in general use that uses reduction
gearing
between the shaft and the prop, Dan.

Many hundreds of examples of Europa aircraft. My friend's Europa runs
the 4-cylinder, opposed, liquid cooled 914S engine at something like
5400RPM in cruise. I think the prop turns less than half that RPM.

Or any Rotax engined plane.

Paul

On 16 Aug 2004 22:13:49 GMT, emove (AJW) wrote:

I don't know of a SEL airplane in general use that uses reduction gearing
between the shaft and the prop, Dan.

They aren't in general use anymore, but ALL the big engined WWII
aircraft used some sort of gear reduction unit to turn the prop, every
single one of them.

You don't see that so much anymore in certified airplanes, but in the
world of experimental homebuilt aircraft where auto conversions are
not uncommon, they are in use.

Corky Scott