Glide

[Bubblehead]

Here a good one. Will a jet liner (ex: AB330) flying at 32K feet glide safely (not totally) if it had its engines shut off?

Bubblehead

[Nexus]

Off course.

The engines generates thrust, the wings generates lift, given that the air flow around the wing has a high velocity.
If you lose all engines, simply put the aircraft into a gentle dive to retain the airspeed that will give you the farthest gliding distance and you'll be allright  :)
That particular airspeed is memorized by EVERY PILOT.
It's called "minimum drag speed" or "Vdmin", and it's located where the zero drag curve meets the induced drag curve, if I'm not mistaken.  :)


There was an Air Transat A330 who made a succesful landing despite running out of fuel in mid air.

[beefhole]

There was an Air Transat A330 who made a succesful landing despite running out of fuel in mid air.

Holds the world record for longest gliding distance.  Glided 74 miles to a safe landing in the Azors.  That's right, they were over the Atlantic when they lost both engines!

Contrary to what is apparently popular belief, no matter what the size of the plane, if the engines fail (while the plane is at cruising alt/speed) it will not drop out of the sky like a brick.  I know when I pull the engine to idle in a 172, I can glide that thing pretty much forever at 67 kts

[beaky]

Just saw a mini-documentary on that particular Air Transat flight... pretty impressive (except for the fact that they decided the computers were screwy instead of taking seriously all the indications that pointed to a fuel leak).
They maintained Vbg (best glide speed, aka "Vdmin", I guess),luckily had a tiny wind generator to maintain minimum electrics and thus hydraulics, and dropped the gear only when the runway was "made". The only problem was that they touched down well over the normal speed, and had no use of thrust buckets or spoilers to slow down with. The tires blew right away, so that helped stop them...
Easy to criticise the crew for not realizing they were low on fuel earlier, but I don't think they'd have made any other field under the circumstances anyway. What's really chilling about the whole story is that they'd been diverted slightly south of their intended course by ATC- had they been on the longer route, they'd have ditched well short of the Azores.
Back to the question:
If it has wings, it will glide- with or without power.

[Nexus]

I'm a sucker for those V-speed accronyms.
Vdmin is the speed where Zero drag equals induced drag, ie where those two curves meet= Minimum drag

But Vbg is more used I suppose, and the definition is also much clearer

[Rocket_Bird]

Just saw a mini-documentary on that particular Air Transat flight... pretty impressive (except for the fact that they decided the computers were screwy instead of taking seriously all the indications that pointed to a fuel leak).

Yeah, I remember the captain was like "Its gotta be the computer..."  

And then drained the fuel by crossfeeding the tanks

"I sure hope it was the computer"

Once they landed he was like "I told you we'd make it"  ;D

[beefhole]

Yeah, I remember the captain was like "Its gotta be the computer..."  

And then drained the fuel by crossfeeding the tanks

"I sure hope it was the computer"

Crossfeeding the tanks was the correct procedure.  It was when the flight crew forgot to close the crossfeed once they knew something was up that exacerbated the problem.  There was no reason for them not to believe it was a computer problem, the indications they were recieving were extremely odd and generally disregarded.

[Ivan]

Just a matter of keeping enough speed for the RAT and hydro systems to keep running.

Project Tupolev Tu-154 can do power-off glides with a realistic hydro system (as: it fails when going below a certain speed)

[Rifleman]

Here a good one. Will a jet liner (ex: AB330) flying at 32K feet glide safely (not totally) if it had its engines shut off?

Bubblehead

Well, you did say "engines shut off" right, ?......not "wings fall off".......

.....its the wings which allow a plane to fly, not the engines.........  ::)

[Alphajet_Enthusiast]

There was an Air Transat A330 who made a succesful landing despite running out of fuel in mid air.

Amazing glide, record wasnt it? Saw a program about it, Air Crash Investigation; although they didnt crash. As long as the Ram Air Turbine is there to provide power to the basic systems I dont see any problem.

[SilverFox441]

Even the F-104 could glide...but it's calculation was much simpler:

1. Are you supersonic?
   If YES, then zoom to maximumatainable altitude.
   If NO, see step 2.

2. Point nose down at 45 deg.

3. Is there a runway in view?

4. If NO, pick a good spot to eject.

[beaky]

Amazing glide, record wasnt it? Saw a program about it, Air Crash Investigation; although they didnt crash. As long as the Ram Air Turbine is there to provide power to the basic systems I dont see any problem.

There were still a few small problems: they were not sure if they could glide far enough to make the airport, they had no flaps, spoilers, or thrust buckets, and absolutely no chance for a go-around.
Other than that- piece of cake!!

[Nexus]

Amazing glide, record wasnt it? Saw a program about it, Air Crash Investigation; although they didnt crash. As long as the Ram Air Turbine is there to provide power to the basic systems I dont see any problem.

You dont see any problem?
Read Rottydaddy's reply and think again.
I see a whole bunch of problems....

[Hagar]

I'm surprised nobody mentioned this. Maybe you're all too young to remember it.
http://en.wikipedia.org/wiki/British_Airways_Flight_009

British Airways Flight 009, sometimes referred to as the Jakarta incident, was a flight from London Heathrow to Auckland, with stops in Bombay, Madras, Kuala Lumpur, Perth and Melbourne. On the 24th of June 1982, it was being flown by G-BDXH City of Edinburgh, a 747-200, when it flew into a cloud of dust and ash thrown up by the eruption of Mount Galunggung, and all four engines failed. The aircraft was able to glide far enough to exit the ash cloud, and three of the engines were restarted, allowing the flight to divert to Jakarta and make a safe landing.

On the flight deck the crew attempted to contact Jakarta for radar assistance, but could not be seen, despite their transponder being set to 7700, the international emergency code. Due to the high Indonesian mountains, an altitude of at least 11,500ft was required to cross the coast safely. Captain Moody decided, that, if the aircraft was unable to maintain altitude by the time they reached 12,000ft, he would turn the aircraft back out to sea and attempt to ditch. The crew began the engine restart drills, despite being well over the recommended maximum altitude of 28,000ft.

Despite the lack of time, Captain Moody made an announcement that has gone down in aviation history as a masterpiece of understatement: "Ladies and Gentlemen, this is your Captain speaking. We have a small problem. All four engines have stopped. We are doing our damnedest to get them going again. I trust you are not in too much distress."

At 13,500ft, the flight crew attempted one last engine restart procedure before turning for the ocean the risky prospect of a water ditching - although there were guidelines, no-one had ever tried it in a 747 - nor have they since. Without warning, number four engine sparked into life, and at 13:56 GMT, Captain Moody used its power to reduce the rate of descent. Shortly therafter, engine three restarted, followed shortly by engines one and two. The crew were amazed at their change of fortune, and requested an increase in altitude to FL150.

As it approached its target altitude, the tracer effect on the windscreen returned without warning. Captain Moody throttled back, but it was too late, and number two engine surged again, and had to be shut down. The crew immediately descended back to FL120.

At last flight 009 approached Jakarta. Despite reports of good visibility, the crew found it hard to see anything, and had to make the approach almost entirely on instruments, despite the glideslope of the ILS being inoperative. Although the runway lights could be made out through a small strip of the windscreen, the landing lights seemed to be inoperable. After landing, the flight crew then found it impossible to taxi, as glare from apron floodlights made the windscreen opaque, and City of Edinburgh had to wait for a tug to tow her in.

PS.

G-BDXH also entered the Guinness Book of Records as the longest glide in a non-purpose built aircraft until it was replaced by the Air Transat Flight 236 incident.

[Rifleman]

There is also the Gimli Glider incident with Air Canada in Manitoba........

...........we've been down this road before about airliners and gliding.........