Testing your glide. Are people doing this?

[Montblack]

("Yossarian" wrote in the Catalina Perep thread)
> My first trip I was that low too, but now my FBO insists on a continuous
> climb to the middle of the channel for better glide distance if your
engine
> quits. 4500' in a 172 is only like 7 miles glide.


I wonder how many people have actually glided their planes (rentals or
otherwise) and so know what their real world glide range numbers will be -
from say, 6,000 ft AGL down to 3,000 ft AGL? Into the wind vs tailwind, etc?

I'm under the impression that 5:1 is a good (safety) number to have in your
head for an average 172 flying at 3,000 ft AGL, and below. Gives you some
"what the hey?" room and *some* turning room.

Can't quite make a 3 mile target with exactly 5:1 at 3,000 ft AGL....15,000
ft. Leaves you 840 ft short of 3 miles. Still, (a mile glide per 1,000 ft of
altitude) seems like a good number to keep in your head for lower altitudes.
Almost 5:1.

I wonder how much better (than the made up safety number 5:1) people will
see up at 6,000 ft AGL. Are people getting book numbers, in their planes,
when they go up and practice real world glides - from say 6k down to 3k?


Montblack
Happy Birthday Kristen
October 25

[Cub Driver]

>Are people getting book numbers, in their planes,
>when they go up and practice real world glides - from say 6k down to 3k?

Be careful up there! I fly at 2900 feet.

all the best -- Dan Ford
email: www.danford.net/letters.htm#9

see the Warbird's Forum at www.warbirdforum.com
and the Piper Cub Forum at www.pipercubforum.com

[Roger Long]

Good thing to do after you have verified your glide (I found the book
numbers on my 172 quite close) is to go to your typical altitude and pick
out a landmark and appropriate distance away. Hold your arm out, put the
tip of your thumb on the horizon, and note where the landmark falls. With
some correction for wind, you now know that you can glide to anything within
that radius.

--
Roger Long

[Happy Dog]

"Montblack" >

> I wonder how much better (than the made up safety number 5:1) people will
> see up at 6,000 ft AGL. Are people getting book numbers, in their planes,
> when they go up and practice real world glides - from say 6k down to 3k?


"Real world" is with the engine out. Prop stopped or creating drag by
windmilling. (Little low? Just use a slightly more aggressive engine
warming.)Which makes me wonder: What if someone, trying this (and it
doesn't sound completely crazy), couldn't restart the engine? (And had a
less than perfect landing...) Is it just the same as a glider making an off
field landing accident?

le moo

[Greg Esres]

<<good number to keep in your head for lower altitudes.>>

Not sure why you refer to "lower altitudes". The glide angle is
constant with altitude.

[Peter Duniho]

"Greg Esres" > wrote in message
...
> <<good number to keep in your head for lower altitudes.>>
>
> Not sure why you refer to "lower altitudes". The glide angle is
> constant with altitude.

Because there's "overhead". Gliding from a higher altitude, one normally
will be able to spend a larger proportion of the glide at the optimal best
glide speed. The glide angle is only theoretically constant with altitude.
In reality, no one goes directly to best glide the instant the engine fails
and the glide angle after engine failure varies as the pilot reacts.

Pete

[Greg Esres]

<<Because there's "overhead". >>

Ah, gotcha.

[Bob]

I'd love to try it in my Pa24 but am worried about thermal shock and
would have to make the prop full coarse to get a good idea of things.




On Sat, 25 Oct 2003 23:06:14 GMT, Greg Esres >
wrote:

><<Because there's "overhead". >>
>
>Ah, gotcha.

[G.R. Patterson III]

Happy Dog wrote:
>
> What if someone, trying this (and it
> doesn't sound completely crazy), couldn't restart the engine? (And had a
> less than perfect landing...) Is it just the same as a glider making an off
> field landing accident?

No. It gets you a suspension for reckless operation of an aircraft. If you
survive.

Oh. By the way. To me, this does sound completely crazy. IMO, someone trying
this should get a revocation, not a suspension.

George Patterson
You can dress a hog in a tuxedo, but he still wants to roll in the mud.

[Jay Honeck]

> Good thing to do after you have verified your glide (I found the book
> numbers on my 172 quite close) is to go to your typical altitude and pick
> out a landmark and appropriate distance away. Hold your arm out, put the
> tip of your thumb on the horizon, and note where the landmark falls. With
> some correction for wind, you now know that you can glide to anything
within
> that radius.

Well, Roger, on a flight to Pella, IA (yep, home of the window manufacturer)
today, I practiced some slow flight and turns around a point, for the first
time in ages.

Not only was it educational for myself and my two young passengers (my son
and his school buddy), but it was fun, too. We were able to do several
turns around a huge fire out in rural Iowa, which gave the kids something to
oooh and aaah about. Seeing a dozen fire trucks from the air is always a
good thing for a couple of 13 year old boys to yack about at school
tomorrow... ;-)

Thanks for the reminder that all of our flights shouldn't be
"droning-to-brunch" flights...
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[[email protected]]

In rec.aviation.owning Happy Dog > wrote:
: "Real world" is with the engine out. Prop stopped or creating drag by
: windmilling.

... as was done on my 4th lesson for my PPL with my instructor.
Not only stopped the engine, but made me slow down to actually stop the
prop. Freaked me out, but he said it was to "prove the airplane doesn't
stop flying when the engine quits." Of course I knew that already, but it
was cool nonetheless. Very (ominously) quiet, too.

-Cory



--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

[Mike Rapoport]

That is the problem practicing emergency procedures in the airplane, you can
make a real emergency out of a pretend one.

Mike
MU-2


"Happy Dog" > wrote in message
. ..
> "Montblack" >
>

> "Real world" is with the engine out. Prop stopped or creating drag by
> windmilling. (Little low? Just use a slightly more aggressive engine
> warming.)Which makes me wonder: What if someone, trying this (and it
> doesn't sound completely crazy), couldn't restart the engine? (And had a
> less than perfect landing...) Is it just the same as a glider making an
off
> field landing accident?
>
> le moo
>
>

[Happy Dog]

"Mike Rapoport" > wrote in message
ink.net...
> That is the problem practicing emergency procedures in the airplane, you
can
> make a real emergency out of a pretend one.

Agreed. But I've heard from more than a few people that their instructor
has done this.

le moo


>
> Mike
> MU-2
>
>
> "Happy Dog" > wrote in message
> . ..
> > "Montblack" >
> >
>
> > "Real world" is with the engine out. Prop stopped or creating drag by
> > windmilling. (Little low? Just use a slightly more aggressive engine
> > warming.)Which makes me wonder: What if someone, trying this (and it
> > doesn't sound completely crazy), couldn't restart the engine? (And had
a
> > less than perfect landing...) Is it just the same as a glider making an
> off
> > field landing accident?
> >
> > le moo
> >
> >
>
>

[David Hill]

Mike Rapoport wrote:
> That is the problem practicing emergency procedures in the airplane, you can
> make a real emergency out of a pretend one.
>
> Mike
> MU-2
>
> "Happy Dog" > wrote in message
> . ..
>
>>"Montblack" >
>>
>
>>"Real world" is with the engine out. Prop stopped or creating drag by
>>windmilling. (Little low? Just use a slightly more aggressive engine
>>warming.)Which makes me wonder: What if someone, trying this (and it
>>doesn't sound completely crazy), couldn't restart the engine? (And had a
>>less than perfect landing...) Is it just the same as a glider making an
>
> off
>
>>field landing accident?
>>
>>le moo

When I was 15 or 16, at an Epps family reunion Doug Epps took me up in a
J-3. He said he wanted to practice deadstick landings.

He'd get over the field (2000' grass), shut down the engine, pull the
nose up until the prop stopped, then land. When we stopped, he'd step
halfway out of the cockpit, reach forward and start the engine, and up
we'd go again.

He started out aiming at midfield and slipping like hell on final. He
worked his way back until the last landing I remember we were skimming
across the bean field, and I was wondering whether we'd make it or not.

It was a while before I realized *everybody* didn't do it that way.
--
David Hill
david at hillREMOVETHISfamily.org
Sautee-Nacoochee, GA, USA

[Trentus]

OK, this is going to sound really silly, but I'm not a pilot,
If planes glide so well, then how come they crash?
It would seem reasonable, that if they glide, and they have an engine
failure etc. that they'd glide them in, not leave smoking craters like the
news tends to show.
Am I missing something here?

Trentus

"Montblack" > wrote in message
...
> ("Yossarian" wrote in the Catalina Perep thread)
> > My first trip I was that low too, but now my FBO insists on a continuous
> > climb to the middle of the channel for better glide distance if your
> engine
> > quits. 4500' in a 172 is only like 7 miles glide.
>
>
> I wonder how many people have actually glided their planes (rentals or
> otherwise) and so know what their real world glide range numbers will be -
> from say, 6,000 ft AGL down to 3,000 ft AGL? Into the wind vs tailwind,
etc?
>
> I'm under the impression that 5:1 is a good (safety) number to have in
your
> head for an average 172 flying at 3,000 ft AGL, and below. Gives you some
> "what the hey?" room and *some* turning room.
>
> Can't quite make a 3 mile target with exactly 5:1 at 3,000 ft
AGL....15,000
> ft. Leaves you 840 ft short of 3 miles. Still, (a mile glide per 1,000 ft
of
> altitude) seems like a good number to keep in your head for lower
altitudes.
> Almost 5:1.
>
> I wonder how much better (than the made up safety number 5:1) people will
> see up at 6,000 ft AGL. Are people getting book numbers, in their planes,
> when they go up and practice real world glides - from say 6k down to 3k?
>
>
> Montblack
> Happy Birthday Kristen
> October 25
>
>

[David Megginson]

"Trentus" > writes:

> OK, this is going to sound really silly, but I'm not a pilot,
> If planes glide so well, then how come they crash?

If cars steer so well, how come *they* crash? In both cases, the
problem is the usually the squishy part sitting on the seat in front
of the controls, not the metal parts.

> It would seem reasonable, that if they glide, and they have an
> engine failure etc. that they'd glide them in, not leave smoking
> craters like the news tends to show.

The news doesn't typically show the ones that glide in, not to mention
the ones that land without incident (i.e. nearly all of them). Here
are some other headlines you don't see:

80M children arrive home from school safely.

Politician not under investigation for corruption.

U.S. doesn't invade Belgium.

Study links weight loss to moderation and exercise.

No bank robberies in state.

Police treat black suspect politely.

Terrorists do not attack museum.

etc. News is the unusual stuff -- it doesn't represent most of what
is going on.


All the best,


David

[Jay Honeck]

> OK, this is going to sound really silly, but I'm not a pilot,
> If planes glide so well, then how come they crash?
> It would seem reasonable, that if they glide, and they have an engine
> failure etc. that they'd glide them in, not leave smoking craters like the
> news tends to show.
> Am I missing something here?

A few disparate points to help you understand the situation better:

- Little planes tend to glide a lot better than big planes.

- Where you lose your engine is important. A little plane losing its engine
over Iowa might make the local newspaper, but everyone will walk away. The
same engine failure over downtown Chicago is going to make national news.

- Smoking holes are created when planes glide into something -- hard. No
matter how well you can glide, sooner or later Mother Earth reaches up to
smite you. If there is a big building or mountain in the way when you run
out of glide, well...

- Smoking holes happen when a pilot allows the plane to slow to a speed at
which the wing no longer creates lift. This is the "stall" speed. A
wing/plane that is stalled takes on the flight characteristics of a load of
sand, and comes down in a hurry, creating a smoking crater.

Hope this helps.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[G.R. Patterson III]

Trentus wrote:
>
> OK, this is going to sound really silly, but I'm not a pilot,
> If planes glide so well, then how come they crash?

They have to have a relatively safe place to come down, and the bigger the
plane is, the bigger and flatter the area has to be. There aren't a whole lot
of places on Long Island (for example) to set down an airliner, and I'd bet
that every one of those places is an airport.

Light aircraft have glide ratios somewhere around 10:1 or 12:1. My aircraft is
close to the latter. That means that I can glide for about 12 miles if I'm 1
mile above the ground and my engine dies. If I have some wind, it will help
me glide further if I turn in the same direction it's blowing and hurt me if
I don't. So. If I can find a fairly flat field at least 300 feet long with no
obstructions like trees or power lines around it, and it's close enough for me
to reach it, I probably won't make one of those holes for the TV guys.

Now. Let's say I'm 100 feet up and the rubber band breaks. That field had better
be *real* close.

Say a 737 loses all power 1 mile up. That pilot needs to find a field at least
3,000 feet long somewhere within about 10 miles. If you want to read about a
pilot in that position who made it, do a Yahoo search for the "Gimli glider".

George Patterson
You can dress a hog in a tuxedo, but he still wants to roll in the mud.

[Mike Rapoport]

"Jay Honeck" > wrote in message
news:DLunb.50518$HS4.232034@attbi_s01...
>
> A few disparate points to help you understand the situation better:
>
> - Little planes tend to glide a lot better than big planes.
>
> - Where you lose your engine is important. A little plane losing its
engine
> over Iowa might make the local newspaper, but everyone will walk away.
The
> same engine failure over downtown Chicago is going to make national news.
>
> - Smoking holes are created when planes glide into something -- hard. No
> matter how well you can glide, sooner or later Mother Earth reaches up to
> smite you. If there is a big building or mountain in the way when you run
> out of glide, well...
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>


Big planes glide much better than small planes. An airliner has about twice
the glide ration that your Pathfinder does.

Mike
MU-2

[Montblack]

("Trentus" wrote)
> OK, this is going to sound really silly, but I'm not a pilot,
> If planes glide so well, then how come they crash?
> It would seem reasonable, that if they glide, and they have an engine
> failure etc. that they'd glide them in, not leave smoking craters like the
> news tends to show.
> Am I missing something here?

From what I gather, one of the main reasons for some of these smoking hole
crashes is a malfunctioning switch, in the pilot's head, that says "Must
save this
airplane."

That switch needs to be set to, "Where should I put this (insurance
company's) plane down to safely dissipate the most energy, before those
forces get to us people?"

Runways, fields, roads, golf courses, high school soccer field, etc.

The question of coming down ....."is moot." You are coming down - now!

This is when the mental switch needs to be thrown from, "save the plane" to
"put it down safely - the heck with the plane."

The other big problem is "Low and Slow."

Low because you have little time to react. Slow - think your motorcycle
going slow and not being able to put your foot down. First you wobble then
you fall to the pavement.

--
Montblack
"Styled by the laws of nature.............Concorde"

[Jay Honeck]

> Big planes glide much better than small planes. An airliner has about
twice
> the glide ration that your Pathfinder does.

Well, the Pathfinder glides like a rock. ;-)

But is that true of all airliners? I guess I would have thought that a
600,000 pound un-powered jetliner wouldn't glide very well.

Of course, the odds of losing all your engines are slim. But then who would
ever believe that they would run the Boeing 307 out of gas?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Happy Dog]

"Trentus" > wrote in message
...
> OK, this is going to sound really silly, but I'm not a pilot,
> If planes glide so well, then how come they crash?
> It would seem reasonable, that if they glide, and they have an engine
> failure etc. that they'd glide them in, not leave smoking craters like the
> news tends to show.
> Am I missing something here?

Apart from your naivete about the broadcast news industry, yes. Very big
planes are very heavy have a big potential energy load and land at speeds
over 100 miles an hour. Very, very hard to make it look pretty on anything
but a long flat surface. Little planes are very light and land at speeds
under 60 miles an hour. Very little energy to dissipate. A pilot current
in forced approaches can land them without much risk of injury anywhere with
a few hundred yards of relatively flat surface or something soft to absorb
the impact.

le moo

[ShawnD2112]

Careful, Jay. A BA 747 flew into the dust cloud from Mount Pinatubo and all
4 engines flamed out. He glided nicely for about 20 minutes until he got
them all to restart at some ridiculously low altitude.

And remember that glide performance has nothing to do with weight but to do
with wing design. And, if I remember correctly, a 747 or like glides just
about like a 172 does, it just needs a faster airspeed to do it, but does it
at the same kind of angle.

But on the subject of the glide ratios of cars, my Mercedes probably glides
a little better than the Pathfinder cuz it's all sleek and aerodynamic-like.
But the Integra's performance was horrible - it didn't glide worth a damn on
the roof!

Shawn
"Jay Honeck" > wrote in message
news:VNwnb.51170$HS4.234123@attbi_s01...
> > Big planes glide much better than small planes. An airliner has about
> twice
> > the glide ration that your Pathfinder does.
>
> Well, the Pathfinder glides like a rock. ;-)
>
> But is that true of all airliners? I guess I would have thought that a
> 600,000 pound un-powered jetliner wouldn't glide very well.
>
> Of course, the odds of losing all your engines are slim. But then who
would
> ever believe that they would run the Boeing 307 out of gas?
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

[Mike Rapoport]

I suspect that the Pathfinder glides about like any fixed gear single and
would be surprised if its glide ratio differed much from a 152 or Cherokee
6.

Jets have glide ratios of up to 20:1. They have no props, dangling gear,
exposed rivits, large openings for cooling ect. The 600,000lb airliner
comes down fast but it goes forward fast too. Remember weight is potential
energy.

My MU-2 has a glide ratio of about 12:1.

Mike
MU-2


"Jay Honeck" > wrote in message
news:VNwnb.51170$HS4.234123@attbi_s01...
> > Big planes glide much better than small planes. An airliner has about
> twice
> > the glide ration that your Pathfinder does.
>
> Well, the Pathfinder glides like a rock. ;-)
>
> But is that true of all airliners? I guess I would have thought that a
> 600,000 pound un-powered jetliner wouldn't glide very well.
>
> Of course, the odds of losing all your engines are slim. But then who
would
> ever believe that they would run the Boeing 307 out of gas?
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

[Ron Natalie]

"Jay Honeck" > wrote in message news:VNwnb.51170$HS4.234123@attbi_s01...

> But is that true of all airliners? I guess I would have thought that a
> 600,000 pound un-powered jetliner wouldn't glide very well.
>
They glide better because they have much less drag. They're slick and don't have
landing gear and other cruft sticking out (and what antennas and stuff they do have
are much smaller in ratio to the overall area).

[Ron Natalie]

"ShawnD2112" > wrote in message ...

> And remember that glide performance has nothing to do with weight but to do
> with wing design. And, if I remember correctly, a 747 or like glides just
> about like a 172 does, it just needs a faster airspeed to do it, but does it
> at the same kind of angle.

Actually, it is a function of the lift and drag. While wing design figures into,
the lack of things sticking out of the fuselage like landing gear, big (compared
to the size of the aircraft) antennas, and an overall more streamlined shape
than Jay's Piper yields much less parasitic drag.

[Robert Moore]

"ShawnD2112" > wrote

> And remember that glide performance has nothing to do with
> weight but to do with wing design.

TRUE!!

> And, if I remember correctly, a 747 or like glides just about
> like a 172 does,

NOT TRUE!! A B-747 has about the same glide ratio as the B-707s
that I flew for 17 years, 20:1 or better. From 35-37,000'(6nm),
we could do 125nm easily.

> it just needs a faster airspeed to do it, but does it at the same
> kind of angle.

TRUE!! About 250kts plus or minus depending on weight.

Bob Moore
PanAm (retired)

[ShawnD2112]

Truer point. That's what I was trying to get at from memory while being too
lazy to pull out my books! :-)

Shawn
"Ron Natalie" > wrote in message
m...
>
> "ShawnD2112" > wrote in message
...
>
> > And remember that glide performance has nothing to do with weight but to
do
> > with wing design. And, if I remember correctly, a 747 or like glides
just
> > about like a 172 does, it just needs a faster airspeed to do it, but
does it
> > at the same kind of angle.
>
> Actually, it is a function of the lift and drag. While wing design
figures into,
> the lack of things sticking out of the fuselage like landing gear, big
(compared
> to the size of the aircraft) antennas, and an overall more streamlined
shape
> than Jay's Piper yields much less parasitic drag.
>
>

[ShawnD2112]

I stand corrected! Didn't realize the glide ratio was that high. Makes my
point even better.

Shawn
"Robert Moore" > wrote in message
. 7...
> "ShawnD2112" > wrote
>
> > And remember that glide performance has nothing to do with
> > weight but to do with wing design.
>
> TRUE!!
>
> > And, if I remember correctly, a 747 or like glides just about
> > like a 172 does,
>
> NOT TRUE!! A B-747 has about the same glide ratio as the B-707s
> that I flew for 17 years, 20:1 or better. From 35-37,000'(6nm),
> we could do 125nm easily.
>
> > it just needs a faster airspeed to do it, but does it at the same
> > kind of angle.
>
> TRUE!! About 250kts plus or minus depending on weight.
>
> Bob Moore
> PanAm (retired)

[markjen]

> Am I missing something here?

Yes, loss of control. This is the key event in most fatal accidents
involving smoking craters - the pilot lost control of the airplane. From
this, springs the adage: Always, ALWAYS, fly the airplane first. Worry
about the other stuff later, but right now, FLY THE AIRPLANE.

- Mark

[markjen]

> They glide better because they have much less drag. They're slick and
don't have
> landing gear and other cruft sticking out (and what antennas and stuff
they do have
> are much smaller in ratio to the overall area).

I had heard that airliners will generally glide a 3 degree glideslope, clean
and power off. Something that GA airplanes have no hope of doing.

It is a FAST ILS though - less than a minute at 250K.

- Mark

[markjen]

> ... as was done on my 4th lesson for my PPL with my instructor.
> Not only stopped the engine, but made me slow down to actually stop the
> prop.

There is always controversy about how realistic to make emergency training.
I think the risk of doing this training outweighs the benefit.

Engine out and windmilling (low pitch if CS) - yes. Stopping the prop - no.

- Mark

[Robert Moore]

"markjen" > wrote
> I had heard that airliners will generally glide a 3 degree
> glideslope, clean and power off. Something that GA airplanes
> have no hope of doing.

If we were on the glideslope "way out", and clean power off, our
biggest problem in the B-707 was slowing to the "gear/flap" speed
without using the speedbrakes which shook the Pax too much.
In the 727, because of the T-mounted horizontal stabilizer, we just
yanked the speedbrake.

Bob Moore

[Kevin McCue]

My instructor was one of them. He did it until the day it became a real
emergency. The FAA's reaction was such that he decided not to do it anymore.
On the other hand, I have gone out to a large mudflat near Tucson in my
Rans and shut it down from 2000' or so and dead sticked it in numerous
times. The flat is about a mile in diameter, Rans uses about 200' to land.
Learned that it glided far better than I was led to believe.

--
Kevin McCue
KRYN
'47 Luscombe 8E
Rans S-17 (for sale)




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[Robert Moore]

"markjen" > wrote

>> . as was done on my 4th lesson for my PPL with my instructor.
>> Not only stopped the engine, but made me slow down to actually
>> stop the prop.
>
> There is always controversy about how realistic to make
> emergency training. I think the risk of doing this training
> outweighs the benefit.

What experience do you have that indicates that this is a risky
maneuver. I made it a point to do it with every one of my students
at 4-5,000' over the not-too-busy airport. With a few hours of
C-172 gliding time, the worst thing that could happen was to land
like any other glider. My homebuilt MiniMax had a 1/2 VW engine
that could not be restarted in-flight. I regularly practiced landing
with the prop stopped in it. Practice builds confidence!
What do glider pilots do when the prop stops? :-) I certainly don't
concede them any basic skills that I don't possess.

Bob Moore
ATP CFI USN
PanAm (retired)

[Jay Honeck]

> NOT TRUE!! A B-747 has about the same glide ratio as the B-707s
> that I flew for 17 years, 20:1 or better. From 35-37,000'(6nm),
> we could do 125nm easily.

Wow -- that's really impressive. (Of course, it's what happens at the END
of the glide that's ulimately the most important, eh? :-)

Thanks for the education, Bob!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[markjen]

> What experience do you have that indicates that this is a risky
> maneuver.

C'mon, common sense says that stopping the prop on an powered airplane is
maneuver that has some risk. As I said there is a tradeoff. Let's not get
into arguing over the tradeoff or what risk is acceptable. This is just a
rehash of the old spin training debate.

And certainly the airplane and environment matters. There is little risk in
practicing very realistic engine-one scenarios in a low-traffic environment
with a plane like a C-172 or VW-powered homebuilt. But it's a whole
different deal in a Bonanza or T210 at a busy field.

You make your own tradeoff, but if I ever have a CFI that wants to practice
the maneuver to the point of stopping the engine, I'll decline and find
another CFI.

- Mark

[Pat Thronson]

Wow, sure did not realize this, thanks
Mike and all.

Pat Thronson PP

"Mike Rapoport" > wrote in message
ink.net...
>
> "Jay Honeck" > wrote in message
> news:DLunb.50518$HS4.232034@attbi_s01...
> >
> > A few disparate points to help you understand the situation better:
> >
> > - Little planes tend to glide a lot better than big planes.
> >
> > - Where you lose your engine is important. A little plane losing its
> engine
> > over Iowa might make the local newspaper, but everyone will walk away.
> The
> > same engine failure over downtown Chicago is going to make national
news.
> >
> > - Smoking holes are created when planes glide into something -- hard.
No
> > matter how well you can glide, sooner or later Mother Earth reaches up
to
> > smite you. If there is a big building or mountain in the way when you
run
> > out of glide, well...
> > Jay Honeck
> > Iowa City, IA
> > Pathfinder N56993
> > www.AlexisParkInn.com
> > "Your Aviation Destination"
> >
>
>
> Big planes glide much better than small planes. An airliner has about
twice
> the glide ration that your Pathfinder does.
>
> Mike
> MU-2
>
>
>

[[email protected]]

In rec.aviation.owning Robert Moore > wrote:
: NOT TRUE!! A B-747 has about the same glide ratio as the B-707s
: that I flew for 17 years, 20:1 or better. From 35-37,000'(6nm),
: we could do 125nm easily.

I thought I heard somewhere that one of the reasons the "glide
ratio" on the bigguns is so high is that it's tested with the turbine's
power pulled all the way back. The engines, however, have a great deal of
idle thrust, which aids in the glide ratio.

I don't know this for sure, but I've heard it's partially true.
Any thoughts?

-Cory

--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

[Mike Rapoport]

No, it is because the airframes are designed for high speed which means low
drag.

Mike
MU-2


> wrote in message
...
> In rec.aviation.owning Robert Moore > wrote:
> : NOT TRUE!! A B-747 has about the same glide ratio as the B-707s
> : that I flew for 17 years, 20:1 or better. From 35-37,000'(6nm),
> : we could do 125nm easily.
>
> I thought I heard somewhere that one of the reasons the "glide
> ratio" on the bigguns is so high is that it's tested with the turbine's
> power pulled all the way back. The engines, however, have a great deal of
> idle thrust, which aids in the glide ratio.
>
> I don't know this for sure, but I've heard it's partially true.
> Any thoughts?
>
> -Cory
>
> --
> ************************************************** ***********************
> * The prime directive of Linux: *
> * - learn what you don't know, *
> * - teach what you do. *
> * (Just my 20 USm$) *
> ************************************************** ***********************
>

[Prime]

"Jay Honeck" > wrote in
news:DLunb.50518$HS4.232034@attbi_s01:

>> OK, this is going to sound really silly, but I'm not a pilot,
>> If planes glide so well, then how come they crash?
>> It would seem reasonable, that if they glide, and they have an engine
>> failure etc. that they'd glide them in, not leave smoking craters
>> like the news tends to show.
>> Am I missing something here?
>
> A few disparate points to help you understand the situation better:
>
> - Little planes tend to glide a lot better than big planes.
>
Sorry Jay! - you need to clarify this. Most little planes do NOT glide
better than big planes. Modern airliners have much better glide ratios
than our factory riveted aluminum craft.

However, those big planes gliding better also *land* at MUCH higher
speeds, and need more runway. Try that on a golf course!

There are a number of cases where jet airliners lost all power and glided
to a perfectly save landing:
- Gimli glider (Air Canada 767)
- A 737 in the south landed on a grass levee when both engines flamed out
after ingesting hail
- A 767 being hijacked glided fine to a water ditching, until the
hijackers attacked the pilots and one of the engines made contact with
the water

> - Where you lose your engine is important. A little plane losing its
> engine over Iowa might make the local newspaper, but everyone will
> walk away. The same engine failure over downtown Chicago is going to
> make national news.
>
> - Smoking holes are created when planes glide into something -- hard.
> No matter how well you can glide, sooner or later Mother Earth
> reaches up to smite you. If there is a big building or mountain in
> the way when you run out of glide, well...
>
> - Smoking holes happen when a pilot allows the plane to slow to a
> speed at which the wing no longer creates lift. This is the "stall"
> speed. A wing/plane that is stalled takes on the flight
> characteristics of a load of sand, and comes down in a hurry, creating
> a smoking crater.
>
> Hope this helps.

[Mike Rapoport]

"Prime" > wrote in message
...
> >
> Sorry Jay! - you need to clarify this. Most little planes do NOT glide
> better than big planes. Modern airliners have much better glide ratios
> than our factory riveted aluminum craft.
>
Airliners glide better than composite light airplanes too.

Mike
MU-2

[Robert Moore]

"Michael Nouak" > wrote
> I'm not saying you're wrong, however I am curious: You "could do
> 125nm easily" how? With the engines shut down? 'Cause that's
> what a glide is to me. At idle you're still producing thrust,
> even more so a flight idle.

Based on the chart numbers for an idle thrust descent,(about 1200#
total for all 4 engines) there wasn't much thrust being developed.
In the old days, our standard descent speed was probably 50-60 kts
above the speed for best L/D and we still flight planned for a
descent distance of 120 nm from FL370 at idle thrust.

Bob Moore

[David CL Francis]

On Tue, 28 Oct 2003 at 16:27:33 in message
<VNwnb.51170$HS4.234123@attbi_s01>, Jay Honeck
> wrote:

>But is that true of all airliners? I guess I would have thought that a
>600,000 pound un-powered jetliner wouldn't glide very well.

The weight makes a difference to the rate of sink but I see no obvious
reason why it should make a big difference to the glide angle. After
all, airliners need good lift drag ratios to make them economical.

The BOAC 747 that lost all engines due to volcanic ash expected to be
able to glide 141 nm from 37,000 ft taking 23 minutes. That's a glide
ratio of over 20 to 1 and around 1600 ft a minute and 240 knots.

They did worse than that because they did not know the best speed and
they needed to maintain the engine start speed. Not only that but they
had no reliable speed measurement either. One pilot had 320knots and the
other had 270 knots on their ASIs - 50 knot difference!. Then they had
to sacrifice height because of loss of pressurization. Of course when
they passed out of the ash they were able to restart.

Ref: Air Disaster Volume 2 by Macarthur Job
--
Francis E-Mail reply to >

[PaulaJay1]

In article >, "Montblack"
> writes:

>From what I gather, one of the main reasons for some of these smoking hole
>crashes is a malfunctioning switch, in the pilot's head, that says "Must
>save this
>airplane."
>
>That switch needs to be set to, "Where should I put this (insurance
>company's) plane down to safely dissipate the most energy, before those
>forces get to us people?"
>
>Runways, fields, roads, golf courses, high school soccer field, etc.
>

At a lecture on "How to crash your plane" that very point was made. He
suggested one of the best choices was a field of fully grown corn. Puts a lot
of "stopping" on the wings even before the wheels touch. Makes you less likely
to pitch over. He even suggested small trees ( and try to go between them and
let the fwings hit.

Chuck

[David Megginson]

"Michael Nouak" > writes:

>> NOT TRUE!! A B-747 has about the same glide ratio as the B-707s
>> that I flew for 17 years, 20:1 or better. From 35-37,000'(6nm),
>> we could do 125nm easily.
>
> I'm not saying you're wrong, however I am curious: You "could do 125nm
> easily" how? With the engines shut down? 'Cause that's what a glide is to
> me. At idle you're still producing thrust, even more so a flight idle.
>
> So, how did you achieve this ratio? In a true glide (presumable tried out in
> a sim), or at flight idle? And if the latter, what would be the difference
> in glide ratio compared to a true glide?

A real life example:

http://www.wadenelson.com/gimli.html

They managed about an 11:1 glideslope, but the flight crew had no
documentation on optimal glide speed for a 767 (they just guessed 220
kias), and they left the engines windmilling.


All the best,


David

[Ron Natalie]

"David Megginson" > wrote in message ...

> They managed about an 11:1 glideslope, but the flight crew had no
> documentation on optimal glide speed for a 767 (they just guessed 220
> kias), and they left the engines windmilling.
>
Can you feather or otherwise stop a turbofan? The compressor seems
to spin around by itself even in a slight breeze on the ground.

[Robert Moore]

David Megginson wrote

> They managed about an 11:1 glideslope, but the flight crew had
> no documentation on optimal glide speed for a 767 (they just
> guessed 220 kias), and they left the engines windmilling.

There is no way that the engines can be prevented from windmilling.
In fact, depending upon altitude, 220 kts should provide enough
engine rpm to do an "air start" if required.

Bob Moore

[Dashii]

"David Megginson" > wrote in message
...
> "Michael Nouak" > writes:
>
> >> NOT TRUE!! A B-747 has about the same glide ratio as the B-707s
> >> that I flew for 17 years, 20:1 or better. From 35-37,000'(6nm),
> >> we could do 125nm easily.
> >
> > I'm not saying you're wrong, however I am curious: You "could do 125nm
> > easily" how? With the engines shut down? 'Cause that's what a glide is
to
> > me. At idle you're still producing thrust, even more so a flight idle.
> >
> > So, how did you achieve this ratio? In a true glide (presumable tried
out in
> > a sim), or at flight idle? And if the latter, what would be the
difference
> > in glide ratio compared to a true glide?
>
> A real life example:
>
> http://www.wadenelson.com/gimli.html
>
> They managed about an 11:1 glideslope, but the flight crew had no
> documentation on optimal glide speed for a 767 (they just guessed 220
> kias), and they left the engines windmilling.

Great story and outcome, I sure hope that they didn't violate any aviation
regulations though, wouldn't want them to be accussed of being "law
breakers"! LOL

That helicopter story was great also, it took real courage to do that.

Dashii
>
>
> All the best,
>
>
> David
>

[David Lesher]

David CL Francis > writes:


>The weight makes a difference to the rate of sink but I see no obvious
>reason why it should make a big difference to the glide angle. After
>all, airliners need good lift drag ratios to make them economical.

Bingo. Less drag == more glide == lower fuel consumption == fewer $$ losses..

Add to the list of "gliders" the one that deadsticked into the Canary Islands
recently after a big fuel leak..


--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

[vincent p. norris]

>Add to the list of "gliders" the one that deadsticked into the Canary Islands
>recently after a big fuel leak..

Since the past tense of "stick" is "stuck,"
shouldn't the past tense of "deadstick" be "deadstuck"?

Sorry, couldn't resist.

vince norris