Can a jet fly upside down

[SiuDude]

This UAL captain doesn't seem to think so. But with a high AOA, I don't see why it wouldn't be possible to sustain flight with a little help from Mr. Newton. Any other ideas?

http://www.usatoday.com/travel/columnist/getline/2004-11-29-ask-the-captain_x.htm

 

[KPTPK]

Look who they asked that question!

 

[belchfire]

Can a jet fly upside down

--------------------------------------------------------------------------------

"This UAL captain doesn't seem to think so. But with a high AOA, I don't see why it wouldn't be possible to sustain flight with a little help from Mr. Newton. Any other ideas?"


It is a shame that all UAL CA's are no longer cigar
smoking veterans of DC-6's. Were that the case,
the sob would be old enough to remember when
the 707 prototype was rolled over Lake Washington
during the demo at the SeaFair Unlimited Hydroplane
Races.

PS...he has also missed the Blue Angles and Thunderbirds
for all of these years, I have seen them upsidedown
with my own eyes. Dumb fuquing dumbfuque!

PPS...Too high of a negative angle of attack will lead
to undesirable things like inverted flat spins and
/or outside snaprolls...the wing only cares that there is
enough air moving across it to generate lift.
Yeah, you could go upside down...do they have inverted
oil and fuel systems to sustain level inverted flight?
(A barrel roll never gets negative) I don't know, but
the Angles and the T-Birds do it on a routine basis.
They're in fighters, not Paxliners. There is only
one thing to limit an inverted glide...distance
between the aircraft and the ground.

If you want to see something really cool, watch
someone doing aerobatics in a sailplane.
Gauranteed to blow your mind!

 

[wingnutt]

PS...he has also missed the Blue Angles and Thunderbirds for all of these years, I have seen them upsidedown with my own eyes. Dumb fuquing dumbfuque!

read the title again silly goose..."Can a commercial jet fly upside down?"

P.S. "he" is actually a "she"

 

[GravityHater]

I don' t think they are talking about Blue Angels or other military a/c, the title says, "Commercial jet..." and I don't think they are talking about a complete roll... the article says, "sustained flight".

I think the questioner means can a 737, 767, RJ, Airbus etc fly upside down for 10 minutes or more?

 

[belchfire]

The only limit to an inverted glide is the
distance between the aircraft and the
ground. I don't know if the fuel system
and oil systems would put up with sustained
inverted level flight...the thread title didn't
say level...just upside down!

 

[flyifrvfr]

I would turn your attention to the Alaska Airline crash a couple of years ago as to whether a commercial jet can fly upside down. In the transcript of the CVR, the Captain clearly states that the jet is atleast flying upside down. The stabilator came away from the jackscrew and they lost pitch control.

Just before the jet took its final plunge, the airplane rolled inverted and flew for a little bit and then continued the dive to the ocean. If the stabilator was still attached, I would argue that a jet can indeed fly upside down, for how long, I don't know.

 

[belchfire]

"Airplane wings have a specific shape — curved on the top and relatively flat on the bottom. Air flowing over the curved top of the wing has to travel faster than the air flowing across the relatively flat bottom of the wing because it has farther to go. This difference creates a low-pressure area (vacuum) on top of the wing, and this is where the majority of our lift is generated.

Flip the airplane over, and the lift is destroyed."

I stand corrected...( there was some confusion on my
part between the thread title and the question posted
to the paper) now, go look at the Supercritical
airfoil on a modern jetliner...damm near symetrical.
Not at all the shape she describes. No prejudice
here as two of my favorite fo's are female...
as well as a couple of my favorite CA's.

For all practical purposes you could use a flat
sheet of any material that would support the
required weight.

To be sure, a different angle of attack would
be required to sustain inverted level flight
than upright level flight. This is because
jetliners are intended to be most efficient
in level cruise flight. Factors included in
this are the angle of incidence of the wing,
thrustline of the engines and so on.

Simply inverting a wing does not destroy
lift. The airfoil (inverted) is now generating
lift in a direction towards the ground! The
direction of airflow is unchanged.
Sufficient change in the angle of attack will
reverse that to a positive lift vector.

Dumbing down basic aeronautics for the
public. Pathetic for a UAL CA of either
gender! See my commment above about
favorite CA's and FO if you suspect me
of prejudice...

Read the editor's note. Just as informative as
the informant, if not more so.

Will the airframe operate in three dimensions?
Yes.
Will the fuel, oil and hydraulic systems
cooperate? Not addressed.

 

[montanapilot]

shes a scab anyway. Twice.

 

[Vladimir Lenin]

she sho' looks like a he

 

[mzaharis]

Two things:

1. Most asymmetrical wings can fly inverted, although they need to achieve a considerably greater angle of attack then when upright. Just look at the graph of lift/Angle of Attack in any aerodynamics textbook that discusses airfoil performance (Abbott and Von Doenhoff immediately comes to mind). This topic was beaten to death in this thread:

http://forums.flightinfo.com/showthread.php?t=40756

2. Despite what was stated in point 1, Tex Johnson's barrel roll in the Dash 80 (the 707 prototype mentioned by Belchfire) is not proof of much other than an airliner has enough roll authority to go inverted. He did a positive 1 G barrel roll; in other words, the wing was always generating lift in the direction in which it was designed, and a passenger would have felt (more or less) his own resting weight pulling him/her into the floor. Any fluid systems would have not had scavenge problems, either, which would probably be one of the quickest problems encountered if you rolled a 707 (or most any other airliner, including the 367-80 707 prototype) inverted with negative G's for any length of time (pretty much any aircraft that is certified as aerobatic is designed with fuel delivery and oiling systems that will work inverted). I am not certain, but I believe that most civil aircraft are tested to withstand some amount of negative G's structurally, just to ensure that they can withstand severe turbulence, so flying upside down is not an immediate guarantee that the wings will fold up.

 

[mzaharis]

Here's some more good stuff on flying inverted with cambered airfoils:


http://www.av8n.com/how/htm/airfoils.html#sec-inverted-camber

 

[typhoonpilot]

Always remember when rolling a commercial jet to keep positive G. If you don't the blue juice comes out of the tank and that makes for a nasty clean-up . For this reason alone, sustained inverted flight would be inadvisable.

Typhoonpilot

 

[Vik]

You know most of those columns are read by your avg Joe and its possible she over-simplified the whole thing and/or overthought it and tried to make it interesting.

Twice a SCAB? yikes. Once is bad enough, but two times.

 

[Lead Sled]

Controlled, inverted flight - not a problem. Sustained inverted flight - for about 15 to 20 seconds, or however long it took for the fuel and oil pickups to become unported and the engines to quit.

Here's a question...

Would aircraft like an MU-2 or Beechjet (that use spoilers for roll control) still have roll control when inverted?

'Sled

 

[EagleRJ]

Would aircraft like an MU-2 or Beechjet (that use spoilers for roll control) still have roll control when inverted?

Good question! I suppose in stable -1G flight, they would act more like drag rudders (like the B2 uses) and would still work a little. You might be able to make use of the Beechjet's yaw/roll coupling, and use the rudder to roll out of it.

Or you could just Split-S out of it!

 

[Sphrynxlla]

it would still have roll control even if it uses spoilerons.

I think a heavy airliners ability to sustain inverted flight is probably also a factor of how much stress its elevator or stab. can handle..

 

[Lead Sled]

it would still have roll control even if it uses spoilerons..

They don't use spoilerons, they just have spoilers.

'Sled

 

[snoopy_1]

No problem

http://forums.avsim.net/dcboard.php?az=show_topic&forum=147&topic_id=173752&mesg_id=173752&page=

 

[rvsm410]

Scale RC aircraft..wings

Even though were talking about full size aircraft, many commercial jets, fighters, and recip aircraft are built in the smaller RC form to exacting reproductions. Granted the weight to power ratio is more, but we have the luxury of flying many types of airfoils in all realms of flight.

Wings with High Dyhedral (sp?) or Swept wings dont like to fly inverted very long, without large amounts of up elevator (while inverted)...they tend to right themselves naturally, Swept wings tend to do nasty things weh inverted, like tip stalls where the aircraft will enter an inverted barrel roll and nose over steeply...

Semitrical wings will fly either way just fine, they dont care which way is up or down, again if they are swept though they will tend to tip stall as the washout no longer supports lift in the correct downward direction....

On the other hand, but enough horsepower behind a brick and it will fly as well...just my experiences with the RC world of flying. I know there are other differences from full scale aircraft, but the wings are surprisingly similar.