Another AirBus-320 question

[pintlar]

I have seen reported that the AirBus-320 has a glide ratio of 1:15.
That was what our pilots told us the wings on Cessna 180-182 (L-19)'s glide
ratio was.
It does not seem consistent that a swept, thin airfoil, wing would have the
same glide ratio as the Cessna.
It is correct the AB-320 has a 1:15 glide ratio at zero power?
Those pilots also said a B-52 and a grand piano have identical glide ratios.

[Bob Kuykendall]

On Jan 21, 7:25*am, "pintlar" > wrote:
> I have seen reported that the AirBus-320 has a glide ratio of 1:15.
> That was what our pilots told us the wings on Cessna 180-182 (L-19)'s glide
> ratio was.
> It does not seem consistent that a swept, thin airfoil, wing would have the
> same glide ratio as the Cessna...

Some of the early smoothbore (straight turbojet) airliners such as 707
and DC-8 had best L/Ds up around 20:1, so I wouldn't be surprised at
15:1 for a high-bypass turbofan airliner, not at all. The sweep makes
it hard to hold laminar flow, but the thinness and high aspect ratio
are good things.

Thanks, Bob K.

[RST Engineering]

Well, let's do the math. The 320 has a best glide speed (max distance) of
about 220 mph while dropping about 1000 fpm at this speed. 220 mph = 3.66
mpm, or about 19,360 fpm. If you go forward 19,360 feet while dropping 1000
feet this is about a 19.36:1 glide ratio. Allowing for other factors not
presented in the data I've seen, 15:1 is eminently reasonable for the A-320.

Jim

--
"It is the mark of an educated mind to be able to entertain a thought
without accepting it."
--Aristotle


"pintlar" > wrote in message
...
>I have seen reported that the AirBus-320 has a glide ratio of 1:15.
> That was what our pilots told us the wings on Cessna 180-182 (L-19)'s
> glide ratio was.
> It does not seem consistent that a swept, thin airfoil, wing would have
> the same glide ratio as the Cessna.
> It is correct the AB-320 has a 1:15 glide ratio at zero power?
> Those pilots also said a B-52 and a grand piano have identical glide
> ratios.
>
>

[Philippe[_2_]]

pintlar s'est penché sur son écritoire, nous avons lu:

> It is correct the AB-320 has a 1:15 glide ratio at zero power?
At M0.8, the ratio is near 1:16
engines iddle, the flight path angle is less than 2.5° at minimum
clean speed. I have no idea about residual thrust....

Consider the cfm56-A have 2500kg thrust at FL350 and maxi cruise. You
may find the real ratio for a heavy plane (weight / 5000) unable to
reach MMo at FL350. Sorry, I never can test.


By
--
Volem rien foutre al païs!
Philippe Vessaire Ò¿Ó¬

[[email protected]]

On Wed, 21 Jan 2009 08:25:49 -0700, "pintlar"
> wrote:

>I have seen reported that the AirBus-320 has a glide ratio of 1:15.
>That was what our pilots told us the wings on Cessna 180-182 (L-19)'s glide
>ratio was.
>It does not seem consistent that a swept, thin airfoil, wing would have the
>same glide ratio as the Cessna.
>It is correct the AB-320 has a 1:15 glide ratio at zero power?
>Those pilots also said a B-52 and a grand piano have identical glide ratios.
>
An a320 pilot I spoke to says the published glide ratio is 20:1 and it
can be stretched to something better than 30:1 with the right weight
and speed.

He said that sometimes the most difficult part of landing an A320-200
is getting the sucker down!

[pintlar]

> It is correct the AB-320 has a 1:15 glide ratio at zero power?
> Those pilots also said a B-52 and a grand piano have identical glide
> ratios.
**********************
.. . . .I long time ago a Canadian pilot nursed a fuel exhausted 737 (mistake
at fuel loading between US and metric gallons) over 100 miles in British
Colombia to land at an abandoned military runway at that time being used as
a auto drag strip. He too was a glider pilot.
.. . . .Then there is the biggest AirBus in the 80's or 90's going East, a
tremendous distance, to glide to the Azores after losing its fuel during a
near fatal fuel transfer process ( damaged piping) to balance the plane. He
landed hotter than hell but managed to get it stopped.
.. . . .It is hard to believe those swept, thin profile airliner wings are
more efficient than those on the 182's. While the 182 wings must be 'low
wing load' type, one would imagine the airliner wing to be the opposite and
not as efficient. Strange, but evidently not true. I would think the drag
of two engine nacelles and windmilling engines, would also lower the drag
ratio. Again, seems I'm wrong.
.. . . .The British fibre glass 'home built' two seater that the TV serial
was made about, (the British Vetinarinan pilot/builder), had its wings
designed by an AirBus engineer. They were supposedly very efficient wings.
Too bad that company is no longer offering those kits. That was a beautiful
plane.

[Peter Dohm]

"pintlar" > wrote in message
...
>I have seen reported that the AirBus-320 has a glide ratio of 1:15.
> That was what our pilots told us the wings on Cessna 180-182 (L-19)'s
> glide ratio was.
> It does not seem consistent that a swept, thin airfoil, wing would have
> the same glide ratio as the Cessna.
> It is correct the AB-320 has a 1:15 glide ratio at zero power?
> Those pilots also said a B-52 and a grand piano have identical glide
> ratios.
>
>
To paraphrase an old movie line: "If the B52 doesn't have a glide ration of
at least 15:1, I'll eat my hat!"

Peter

[[email protected]]

On Wed, 21 Jan 2009 16:05:30 -0700, "pintlar"
> wrote:

>> It is correct the AB-320 has a 1:15 glide ratio at zero power?
>> Those pilots also said a B-52 and a grand piano have identical glide
>> ratios.
>**********************
>. . . .I long time ago a Canadian pilot nursed a fuel exhausted 737 (mistake
>at fuel loading between US and metric gallons) over 100 miles in British
>Colombia to land at an abandoned military runway at that time being used as
>a auto drag strip. He too was a glider pilot.

Not BC - Manitoba - the "Gimli Glider"
>. . . .Then there is the biggest AirBus in the 80's or 90's going East, a
>tremendous distance, to glide to the Azores after losing its fuel during a
>near fatal fuel transfer process ( damaged piping) to balance the plane. He
>landed hotter than hell but managed to get it stopped.
>. . . .It is hard to believe those swept, thin profile airliner wings are
>more efficient than those on the 182's. While the 182 wings must be 'low
>wing load' type, one would imagine the airliner wing to be the opposite and
>not as efficient. Strange, but evidently not true. I would think the drag
>of two engine nacelles and windmilling engines, would also lower the drag
>ratio. Again, seems I'm wrong.
>. . . .The British fibre glass 'home built' two seater that the TV serial
>was made about, (the British Vetinarinan pilot/builder), had its wings
>designed by an AirBus engineer. They were supposedly very efficient wings.
>Too bad that company is no longer offering those kits. That was a beautiful
>plane.
>

[pintlar]

> To paraphrase an old movie line: "If the B52 doesn't have a glide ration
> of at least 15:1, I'll eat my hat!"
>
> Peter
*******************************
I was lead to believe the B-52's wing took a negative angle of attack when
the engines lost power. For the crew, that is nice to know that this is not
true.

[Alan Baker]

In article >,
"pintlar" > wrote:

> > It is correct the AB-320 has a 1:15 glide ratio at zero power?
> > Those pilots also said a B-52 and a grand piano have identical glide
> > ratios.
> **********************
> . . . .I long time ago a Canadian pilot nursed a fuel exhausted 737 (mistake
> at fuel loading between US and metric gallons) over 100 miles in British
> Colombia to land at an abandoned military runway at that time being used as
> a auto drag strip. He too was a glider pilot.

Not quite correct. Google "gimli glider"...

The aircraft was a 767, the flight took off from Montreal and made its
forced landing in Gimli, Manitoba, I don't think they made it 100 miles,
....

....and the confusion as caused by an incorrect conversion from litres to
kilograms and back again, leading to an incorrect amount of fuel being
added in Montreal (they used the figure for litres to pounds and so
ended up with 22,300 lb of fuel and not 22,300 kg).


For further details:

<http://en.wikipedia.org/wiki/Gimli_Glider>

> . . . .Then there is the biggest AirBus in the 80's or 90's going East, a
> tremendous distance, to glide to the Azores after losing its fuel during a
> near fatal fuel transfer process ( damaged piping) to balance the plane. He
> landed hotter than hell but managed to get it stopped.
> . . . .It is hard to believe those swept, thin profile airliner wings are
> more efficient than those on the 182's. While the 182 wings must be 'low
> wing load' type, one would imagine the airliner wing to be the opposite and
> not as efficient. Strange, but evidently not true. I would think the drag
> of two engine nacelles and windmilling engines, would also lower the drag
> ratio. Again, seems I'm wrong.
> . . . .The British fibre glass 'home built' two seater that the TV serial
> was made about, (the British Vetinarinan pilot/builder), had its wings
> designed by an AirBus engineer. They were supposedly very efficient wings.
> Too bad that company is no longer offering those kits. That was a beautiful
> plane.

--
Alan Baker
Vancouver, British Columbia
<http://gallery.me.com/alangbaker/100008/DSCF0162/web.jpg>

[jan olieslagers[_2_]]

pintlar schreef:
> . . . .The British fibre glass 'home built' two seater that the TV serial
> was made about, (the British Vetinarinan pilot/builder), had its wings
> designed by an AirBus engineer. They were supposedly very efficient wings.
> Too bad that company is no longer offering those kits. That was a beautiful
> plane.

That sounds like the Europa, to my knowledge the kit is still available.
Even offering an alternative "motor-glider" wing.

[Highflyer]

"pintlar" > wrote in message
...

> I was lead to believe the B-52's wing took a negative angle of attack when
> the engines lost power. For the crew, that is nice to know that this is
> not true.
>
>

I think you will find, with ANY airplane, that the angle of attack is
solely dependant upon the airspeed and the weight. It would not be
expected to change in any way by any power setting, from zero to
max.

Notice that this is definately NOT true for a powered rotary wing
aircraft! :-)

Highflyer
Highflight Aviation Services
Pinckneyville Airport PJY

[[email protected]]

On Thu, 19 Feb 2009 23:47:51 -0600, "Highflyer" > wrote:

>
>"pintlar" > wrote in message
...
>
>> I was lead to believe the B-52's wing took a negative angle of attack when
>> the engines lost power. For the crew, that is nice to know that this is
>> not true.
>>
>>
>
>I think you will find, with ANY airplane, that the angle of attack is
>solely dependant upon the airspeed and the weight. It would not be
>expected to change in any way by any power setting, from zero to
>max.
>
>Notice that this is definately NOT true for a powered rotary wing
>aircraft! :-)
>
>Highflyer
>Highflight Aviation Services
>Pinckneyville Airport PJY
>
It is not at all uncommon for a plane to "change trim" with
application of power - add power and many planes will "nose up"
slightly, and back the power down and they "nose down".

This is preferable to the opposite condition, which can happen on the
likes of a Lake or SeaBee. Upthrust od downthrust designed into the
mount combined with the location of the engine is usually calculated
to reduce the effect by tending to cancel each other out, but the
combination is not always totally effective.

[cavelamb[_2_]]

Highflyer wrote:
> "pintlar" > wrote in message
> ...
>
>> I was lead to believe the B-52's wing took a negative angle of attack when
>> the engines lost power. For the crew, that is nice to know that this is
>> not true.
>>
>>
>
> I think you will find, with ANY airplane, that the angle of attack is
> solely dependant upon the airspeed and the weight. It would not be
> expected to change in any way by any power setting, from zero to
> max.
>
> Notice that this is definately NOT true for a powered rotary wing
> aircraft! :-)
>
> Highflyer
> Highflight Aviation Services
> Pinckneyville Airport PJY
>
>


I think you might say *range* of available angle of Attack?

Or AOA for straight and level flight?

Because at any weight and airspeed, I've always been able to
pull the nose up or down - changing the AOA.

[Philippe[_2_]]

cavelamb a fait l'effort d'écrire:

> Because at any weight and airspeed, I've always been able to
> pull the nose up or down - changing the AOA.
And you change the speed or the thrust settings (or both)...

For one weight and one speed, you have one AOA... You may have many
fligt path angle, according to the thrust....



--
« Si tous les poètes voulaient se donner la main, ils toucheraient enfin
des doigts d'auteur! »
Philippe Vessaire Ò¿Ó¬

[cavelamb himself[_5_]]

Philippe wrote:
> cavelamb a fait l'effort d'écrire:
>
>> Because at any weight and airspeed, I've always been able to
>> pull the nose up or down - changing the AOA.
> And you change the speed or the thrust settings (or both)...
>
> For one weight and one speed, you have one AOA... You may have many
> fligt path angle, according to the thrust....
>
>
>
And when changing thrust?

[Philippe[_2_]]

cavelamb himself a fait l'effort d'écrire:

>> For one weight and one speed, you have one AOA... You may have many
>> fligt path angle, according to the thrust....
>>
>>
>>
> And when changing thrust
You will have new FPa, or rate of climb/decsent but you keep the
same AOA


--
« Si tous les poètes voulaient se donner la main, ils toucheraient enfin
des doigts d'auteur! »
Philippe Vessaire Ò¿Ó¬

[Brian Whatcott]

Highflyer wrote:
> "pintlar" > wrote in message
> ...
>
>> I was lead to believe the B-52's wing took a negative angle of attack when
>> the engines lost power. For the crew, that is nice to know that this is
>> not true.
>>
>>
>
> I think you will find, with ANY airplane, that the angle of attack is
> solely dependant upon the airspeed and the weight. It would not be
> expected to change in any way by any power setting, from zero to
> max.
>
> Notice that this is definately NOT true for a powered rotary wing
> aircraft! :-)
>
> Highflyer
> Highflight Aviation Services
> Pinckneyville Airport PJY
>
>

For large passenger aircraft, designers attempt to ameliorate loads
by balancing one effect against another.
An example: if you put fuel tanks in the fuselage, the wing bending
moment is greatest with full tanks. If you put fuel tanks in the wings,
the in flight bending moment is LEAST with full tanks.

In the same way, to ameliorate the wing twisting moment due to engine
thrust which increases with thrust, if the engines are set well forward
of the wing center of rotation which twists the wing down towards the
tips, the twisting moment DECREASES with increasing thrust (this is a
balancing act, of course...)

This design effort has the effect of increasing AofA with thrust, which
is a stabilizing factor.

Another design choice affecting AofA is Wing sweep.
Forward sweep has efficiency benefits, but was often considered a lethal
choice. A bump which increased wing bending moment also increases AofA
in swept forward designs, but AofA decreases in Swept back designs.
The later is a load-shedding effect. The former effect is a load
multiplying effect, just when you don't want it.

Brian W

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