Can a jet fly upside down

[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.