So you think you have a low glide ratio!

The January 2006 issue of AOPA Pilot has an article about a Pilatus PC-12
single engine turboprop. Beautiful airplane.

In the article is the following comment: "It's a great glider. ... the PC-12
has a 2.7-1 power off glide ratio at maximum gross weight - not bad at all
for a 9,920 pound airplane".

Just for reference, I calculated the glide ratio of the Schweizer 300C
helicopter I was flying and it is not far off from that, engine out. I
never could attain the calculated glide ratio with the helicopter, though.

I would never call anything with a 2.7-1 glide ratio as being great,
although it probably is better than the space shuttle.

Colin

COLIN LAMB wrote:
The January 2006 issue of AOPA Pilot has an article about a Pilatus PC-12
single engine turboprop. Beautiful airplane.

In the article is the following comment: "It's a great glider. ... the PC-12
has a 2.7-1 power off glide ratio at maximum gross weight - not bad at all
for a 9,920 pound airplane".

Just for reference, I calculated the glide ratio of the Schweizer 300C
helicopter I was flying and it is not far off from that, engine out. I
never could attain the calculated glide ratio with the helicopter, though.

I would never call anything with a 2.7-1 glide ratio as being great,
although it probably is better than the space shuttle.

I saw that too and figured it's gotta be a typo.

Shawn

I think that just has to be a typo... most training Cezzna's are about 7 to
1.
But it would be hard to believe the Pc-12 could get 27/1... I'd believe
maybe 10 or 12 to 1.

3/1 is not much better than a brick. (1/1)
BT

"COLIN LAMB" wrote in message
ink.net...
The January 2006 issue of AOPA Pilot has an article about a Pilatus PC-12
single engine turboprop. Beautiful airplane.

In the article is the following comment: "It's a great glider. ... the
PC-12 has a 2.7-1 power off glide ratio at maximum gross weight - not bad
at all for a 9,920 pound airplane".

Just for reference, I calculated the glide ratio of the Schweizer 300C
helicopter I was flying and it is not far off from that, engine out. I
never could attain the calculated glide ratio with the helicopter, though.

I would never call anything with a 2.7-1 glide ratio as being great,
although it probably is better than the space shuttle.

Colin

My Mooney has 12 to 1 with prop stopped (not windmilling). The PC-12 has
less cooling drag plus the prop feathers too. So I would expect it to be
better than 12/1.

I have a friend who has a PC-12 . . . I could ask.

bumper


"BTIZ" wrote in message
news:cR_vf.8501$V.4724@fed1read04...
I think that just has to be a typo... most training Cezzna's are about 7 to
1.
But it would be hard to believe the Pc-12 could get 27/1... I'd believe
maybe 10 or 12 to 1.

3/1 is not much better than a brick. (1/1)
BT

"COLIN LAMB" wrote in message
ink.net...
The January 2006 issue of AOPA Pilot has an article about a Pilatus PC-12
single engine turboprop. Beautiful airplane.

In the article is the following comment: "It's a great glider. ... the
PC-12 has a 2.7-1 power off glide ratio at maximum gross weight - not bad
at all for a 9,920 pound airplane".

Just for reference, I calculated the glide ratio of the Schweizer 300C
helicopter I was flying and it is not far off from that, engine out. I
never could attain the calculated glide ratio with the helicopter,
though.

I would never call anything with a 2.7-1 glide ratio as being great,
although it probably is better than the space shuttle.

Colin

In article cR_vf.8501$V.4724@fed1read04,
"BTIZ" wrote:

I think that just has to be a typo... most training Cezzna's are about 7 to
1.
But it would be hard to believe the Pc-12 could get 27/1... I'd believe
maybe 10 or 12 to 1.

3/1 is not much better than a brick. (1/1)

Thatlooks like a sin == tan error. Lift is the component of
aerodynamic force that is perpendicular to the relative airflow, not the
component that is vertically upward. The L/D of a brick is not 1:1 --
which would imply it could fly at an angle of descent of 45 degrees --
but very close to zero.

Well, ok, a canonball has an L/D of zero, if it is not spinning. A
brick would have a slightly better L/D, if you could stabilize it,
perhaps by spinning it, as with a ruler or business card which appear to
have L/Ds of about 1 in stabilized backward-tumbling flight. Maybe a
brick could do that too, at sufficiently high speed?

--
Bruce | 41.1670S | \ spoken | -+-
Hoult | 174.8263E | /\ here. | ----------O----------

true bruce.. I miss spoke.. a one to one would be 1ft down for every 1 ft
forward.. or about 45degree glide.. I don't think even a tumbling brick
could do that.. maybe 0/1
BT

"Bruce Hoult" wrote in message
...
In article cR_vf.8501$V.4724@fed1read04,
"BTIZ" wrote:

I think that just has to be a typo... most training Cezzna's are about 7
to
1.
But it would be hard to believe the Pc-12 could get 27/1... I'd believe
maybe 10 or 12 to 1.

3/1 is not much better than a brick. (1/1)

Thatlooks like a sin == tan error. Lift is the component of
aerodynamic force that is perpendicular to the relative airflow, not the
component that is vertically upward. The L/D of a brick is not 1:1 --
which would imply it could fly at an angle of descent of 45 degrees --
but very close to zero.

Well, ok, a canonball has an L/D of zero, if it is not spinning. A
brick would have a slightly better L/D, if you could stabilize it,
perhaps by spinning it, as with a ruler or business card which appear to
have L/Ds of about 1 in stabilized backward-tumbling flight. Maybe a
brick could do that too, at sufficiently high speed?

--
Bruce | 41.1670S | \ spoken | -+-
Hoult | 174.8263E | /\ here. | ----------O----------

COLIN LAMB wrote:

The January 2006 issue of AOPA Pilot has an article about a Pilatus PC-12
single engine turboprop. Beautiful airplane.

In the article is the following comment: "It's a great glider. ... the
PC-12 has a 2.7-1 power off glide ratio at maximum gross weight - not bad
at all for a 9,920 pound airplane".

According to Pilatus, the actual number is 12:1
http://www.pilatus-aircraft.com/medi...nglish-Imp.pdf

....or 2.6nm per 1000'.


Google "pc12 glide ~performance" = 3rd hit for the info above

Happy soaring all!

James
--
The reader this message encounters not failing to understand is cursed.

Centurion wrote:
COLIN LAMB wrote:

According to Pilatus, the actual number is 12:1
http://www.pilatus-aircraft.com/medi...nglish-Imp.pdf

...or 2.6nm per 1000'.


Using the FAA "definition" of 1 nm = 6000 feet, that equates to

2.6*6000/1000 = 15.6:1 ~3.667 degrees
which matches the 16:1 (not 12:1) I noticed in the above performance
document.

I once heard a 727 had a 27:1 glide ratio, power off, clean...

And some of my co-worker test pilots encountered mountain wave in a
130,000 lb MD-90, and had the opportunity to find out that it would
maintain altitude at idle power...

COLIN LAMB schreef:

The January 2006 issue of AOPA Pilot has an article about a Pilatus PC-12
single engine turboprop. Beautiful airplane.

In the article is the following comment: "It's a great glider. ... the PC-12
has a 2.7-1 power off glide ratio at maximum gross weight - not bad at all
for a 9,920 pound airplane".

Just for reference, I calculated the glide ratio of the Schweizer 300C
helicopter I was flying and it is not far off from that, engine out. I
never could attain the calculated glide ratio with the helicopter, though.

I would never call anything with a 2.7-1 glide ratio as being great,
although it probably is better than the space shuttle.

Colin

On a French site I saw an l/d of about 12 which seems realistic and not
uncommen for that kind a aircraft.

The emergency parachute I wear in my glider has a 3.5:1 glide ratio. I
think that's good.
Jim