View Full Version : So you think you have a low glide ratio!
COLIN LAMB
January 7th 06, 05:57 PM
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
Shawn
January 7th 06, 06:35 PM
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
BTIZ
January 8th 06, 02:34 AM
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
>
bumper
January 8th 06, 03:27 AM
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$V.4724@fed1read04...
>I think that just has to be a typo... most training Cezzna's are about 7 to
>1.
> But it would be hard to believe the Pc-12 could get 27/1... I'd believe
> maybe 10 or 12 to 1.
>
> 3/1 is not much better than a brick. (1/1)
> BT
>
> "COLIN LAMB" > wrote in message
> ink.net...
>> The January 2006 issue of AOPA Pilot has an article about a Pilatus PC-12
>> single engine turboprop. Beautiful airplane.
>>
>> In the article is the following comment: "It's a great glider. ... the
>> PC-12 has a 2.7-1 power off glide ratio at maximum gross weight - not bad
>> at all for a 9,920 pound airplane".
>>
>> Just for reference, I calculated the glide ratio of the Schweizer 300C
>> helicopter I was flying and it is not far off from that, engine out. I
>> never could attain the calculated glide ratio with the helicopter,
>> though.
>>
>> I would never call anything with a 2.7-1 glide ratio as being great,
>> although it probably is better than the space shuttle.
>>
>> Colin
>>
>
>
Bruce Hoult
January 8th 06, 03:27 AM
In article <cR_vf.8501$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----------
BTIZ
January 8th 06, 04:07 AM
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----------
Centurion
January 8th 06, 07:32 AM
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/media/PC-12_Performance_English-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.
309
January 8th 06, 09:31 AM
Centurion wrote:
> COLIN LAMB wrote:
>
> According to Pilatus, the actual number is 12:1
> http://www.pilatus-aircraft.com/media/PC-12_Performance_English-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.
JS
January 8th 06, 12:26 PM
The emergency parachute I wear in my glider has a 3.5:1 glide ratio. I
think that's good.
Jim
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.
>
> Colin
Colin:
I've been thru the SIMCOM school on the PC12 and have about five
hundred hours in it. I'm guessing that should have read 12.7 to 1.
Because SIMCOM's program is designed for relatively low time pilots
with not a lot of exprience flying high performance birds, my sim
instructor was letting us shoot most of our approaches with the engine
shut down and the prop feathered. He was also a glider pilot and
understood energy management. By flying a bit fast and a dot and one
half high on the glide slope, (and holding on the landing gear until
DH), it was possible to make dead stick approaches. Non precision
approaches were a bit harder with no engine. Because the sim is
non-motion we also did akro in it, that is loops and rolls. All that
in sunny fla. in the dead of winter. Billy Hill, Zulu
Colin:
The article in AOPA talks about SIMCOM which is the only certified
PC-12 sim school in the US. Their program is designed for relatively
low time pilots transitioning into bigger and faster aircraft. When I
was there I had the good luck to have a sim instructor who was also a
glider pilot, so after getting the basics out of the way, we did most
of our approaches with the engine shut down and the prop feathered.
The glide ratio is about 12 to 1 and if you fly the approach at about
130 kts., stay about a dot and one half high on the glide slope and
hold off on the landing gear until DH, you can make a very nice dead
stick ILS. Non-precision approaches are a bit more difficult. Because
the sim is non motion, we did loops and rolls with it. All this in
sunny fla. in the dead of winter!
The PC-12 is one great aircraft! It runs with a KingAir 200 and will
land almost as short as a Cessna Caravan (which anything but a nice
aircraft.) I've got about 500 hours in one and miss flying it. The
company I was working for, a part 135 operator here in NM went out of
business.
Billy Hill, Zulu
I spent amost a week in sunny Fla. at PC-12 ground school which
included a goodly number of hours in the simulator which, as the
article in AOPA mentions is non-motion. The school is an extensive one
and is designed for low time pilots with little or no exprience in high
performance turbo props. My sim instructor was a glider pilot so we
spent most of the time shooting insturment approaches with the engine
shut down and the prop feathered. If you start the approach with a
little extra energy and stay about a dot and one half high on the glide
slope and then hold on the landing gear until DH, an engine out
approach is no problem. Non-precision approaches are a bit harder.
Because the sim is non-motion, we did loops and rolls with it.
I've got about 500 hours in the PC-12; it will run with a KingAir 200
and land almost as short as a Cessna Caravan. If the part 135 company
here in NM had not gone out of business, I would still be flying one.
Billy Hill, Zulu
Yes, the PC-12 has a 12 to 1 glide ratio and with the prop feathered
glides quite nicely. At least the simulator does. I spent a week in
sunny Fla. last winter going thru SIMCOM PC-12 school which is designed
for low time pilots with little or no turbo prop time. My sim
instructor was a glider pilot and so we spend most of our time shooting
insturment approaches with the engine shut off. One need only carry a
bit of extra airspeed, fly the glide slope a dot and one half high and
save the landing gear until reaching DH. Non-precision approaches are a
bit more difficult. You can also both loop and roll the sim. The
part135 company I was flying for here in NM went TU or I would still be
flying the Platapus. It will run with a KingAir 200 and land almost as
short as a Cessna Caravan and of course was made by folks who know
gliders.
Billy Hill, Zulu
The PC-12 does have a 12 to 1 glide ratio. I spent a week in sunny
Fla. during Dec. '04 going thru SIMCOM's PC-12 school. It's designed
for relatively low time pilots with little or no turbo time. My sim
instructor was a glider pilot who had me doing engine off instrument
approaches. You just carry a bit more airspeed, fly the glide slope a
dot and one half high and save the gear until reaching DH and its a
cake walk. Non-precision approaches are more difficult. The sim,
which is non motion can also be looped and rolled.
The Platapus will run with a KingAir 200 and land almost as short as a
Cessna Caravan, and if the Part 135 company I was working for had not
gone T.U. I would still be flying one.
Billy Hill, Zulu
Don Hammer
January 8th 06, 05:31 PM
The Boeing 707-300 is 19.5:1
JS
January 8th 06, 07:51 PM
I think my emergency parachute with 3.5:1 has a good glide ratio.
JS
January 8th 06, 07:57 PM
<< 3/1 is not much better than a brick. >>
I think that the 3.5:1 of my emergency parachute is good!
Jim
I would guess that the glide ratio would be about 8 to 1?
Bruce Hoult
January 9th 06, 12:03 AM
In article >,
Don Hammer > wrote:
> The Boeing 707-300 is 19.5:1
As someone pointed out to me recently, that's probably engines at flight
idle, not shut down.
--
Bruce | 41.1670S | \ spoken | -+-
Hoult | 174.8263E | /\ here. | ----------O----------
GM
January 9th 06, 12:05 AM
Don Hammer wrote:
> The Boeing 707-300 is 19.5:1
I had several cockpit rides (pre 9/11) in various Airbus types in
Germany. Some of the pilots were actually active glider pilots. They
claimed an L/D in the mid 20's, if they make the engines drag-wise
'disappear' by keeping them going at slightly above idle speed.
Remember the 'Gimli Glider', the Air Canada B767, that ran out of fuel?
Nice write-up at http://www.wadenelson.com/gimli.html
The author states an 11:1 glide ratio for this 132t glider with two
wind-milling P&W engines and a RAT sticking out of it's belly.
Just out of curiosity - does anyone have a number for the
space-shuttle?
Uli Neumann
Libelle 'GM'
GM
January 9th 06, 12:13 AM
I had several (pre 9/11) cockpit rides in various Airbus types over
Germany. Some of the crew members were active glider pilots and they
claimed an L/D in the mid 20's, if they make the engines 'disappear'
drag-wise by keeping them going a bit above idle speed.
Remember the 'Gimli Glider', the Air Canada B767, that ran out of fuel?
There is a nice write-up at http://www.wadenelson.com/gimli.html
The author states a 11:1 for this 132t glider with two wind-milling P&W
engines and a RAT hanging out of it's belly.
Just out of curiosity - does anyone have a number for the space
shuttle?
Uli Neumann
Libelle 'GM'
Shawn wrote:
> 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
Pilatus' web site states that the glide ratio of a PC-12 is 16:1.
It is a very clean aircraft (as turboprops go), but the wing loading is
35 lb./ft2. 16:1 seems optimistic, but I since it is on the internet,
I am sure that it is true.
Bob Zahradnik
Pilatus' web site states that the glide ratio of a PC-12 is 16:1.
It is a very clean aircraft (as turboprops go), but the wing loading is
35 lb./ft2. 16:1 seems optimistic, but I since it is on the internet,
I am sure that it is true.
Bob Zahradnik
bumper
January 9th 06, 06:45 AM
Just got an answer from my friend who owns a 2 year old PC-12. Glide ratio
is 12:1 or approx. 2 nm per 1000 ft.
My Mooney 201 is the same, but lots cheaper!
All else being equal, the probability that I might "test" the Mooney's glide
ratio some day is much more than the chance of that PT-6 going quiet.
bumper
> wrote in message
oups.com...
> Pilatus' web site states that the glide ratio of a PC-12 is 16:1.
>
> It is a very clean aircraft (as turboprops go), but the wing loading is
> 35 lb./ft2. 16:1 seems optimistic, but I since it is on the internet,
> I am sure that it is true.
>
> Bob Zahradnik
>
Charles Yeates
January 9th 06, 09:22 AM
Taking off in a Mooney 201 from Albury-Woodonga in NSW, OZ, years ago
during a coast-to-coast and return holiday adventure, Kris and I had
just completed a right turnout when the engine swallowed an exhaust
valve and clattered to a stop. “Albury Tower, Mooney NWF is returning
immediately.” From 1100’ we had height for a truncated right hand
circuit back onto the runway and enough ground speed to roll off onto a
ramp parking spot. The Tower asked why an emergency had not been
declared – too busy said I – probably just as well, they replyed:
otherwise you would have been filling out paperwork for a week.
Kris and I hitched a ride to Tocumwal and enjoyed a soaring week while a
new engine was fitted to the Mooney. The ship’s owner had one in Perth
awaiting our return. The glide ratio was sufficient. BTW, that was the
only engine failure so far in 60 years of flying.
bumper wrote:
> Just got an answer from my friend who owns a 2 year old PC-12. Glide ratio
> is 12:1 or approx. 2 nm per 1000 ft.
>
> My Mooney 201 is the same, but lots cheaper!
>
> All else being equal, the probability that I might "test" the Mooney's glide
> ratio some day is much more than the chance of that PT-6 going quiet.
>
> bumper
>
> > wrote in message
> oups.com...
>
>>Pilatus' web site states that the glide ratio of a PC-12 is 16:1.
>>
>>It is a very clean aircraft (as turboprops go), but the wing loading is
>>35 lb./ft2. 16:1 seems optimistic, but I since it is on the internet,
>>I am sure that it is true.
>>
>>Bob Zahradnik
>>
>
>
>
--
Charles Yeates
ZS Jezow PW-6U & PW-5
http://www3.ns.sympatico.ca/yeatesc/world.html
For Example John Smith
January 11th 06, 08:52 PM
Found a number of docs that refer to it as 22 degrees at 360mph
I've understood it to be about 4:1, but I don't do much math so I can't
convert the 22 degrees into a L:D.....
"GM" > wrote in message
ups.com...
>I had several (pre 9/11) cockpit rides in various Airbus types over
> Germany. Some of the crew members were active glider pilots and they
> claimed an L/D in the mid 20's, if they make the engines 'disappear'
> drag-wise by keeping them going a bit above idle speed.
>
> Remember the 'Gimli Glider', the Air Canada B767, that ran out of fuel?
> There is a nice write-up at http://www.wadenelson.com/gimli.html
> The author states a 11:1 for this 132t glider with two wind-milling P&W
> engines and a RAT hanging out of it's belly.
>
> Just out of curiosity - does anyone have a number for the space
> shuttle?
>
> Uli Neumann
> Libelle 'GM'
>
Bruce Hoult
January 11th 06, 10:25 PM
In article >,
"For Example John Smith" > wrote:
> Found a number of docs that refer to it as 22 degrees at 360mph
> I've understood it to be about 4:1, but I don't do much math so I can't
> convert the 22 degrees into a L:D.....
The number I saw was 18 degrees at approach speed, which is about 200
knots. That's 3:1. 22 degrees is 2.5:1.
To go from the angle to the glide ratio calculate 1/tan(angle).
--
Bruce | 41.1670S | \ spoken | -+-
Hoult | 174.8263E | /\ here. | ----------O----------
For Example John Smith
January 12th 06, 02:47 PM
I don't tan (skin cancer)
sine (don't know any deaf people)
or cosine (got burned once by a "friend" on a loan).
"Bruce Hoult" > wrote in message
...
> In article >,
> "For Example John Smith" > wrote:
>
>> Found a number of docs that refer to it as 22 degrees at 360mph
>> I've understood it to be about 4:1, but I don't do much math so I can't
>> convert the 22 degrees into a L:D.....
>
> The number I saw was 18 degrees at approach speed, which is about 200
> knots. That's 3:1. 22 degrees is 2.5:1.
>
> To go from the angle to the glide ratio calculate 1/tan(angle).
>
> --
> Bruce | 41.1670S | \ spoken | -+-
> Hoult | 174.8263E | /\ here. | ----------O----------
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