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PAXboy
21st May 2002, 20:05
OK, so that's the helicopter question dealt with :D

How would main line passenger aircraft fare, if they tried it inverted? Is the problem becoming inverted (in a controlled manner!) or would be staying there?

Dan Winterland
21st May 2002, 20:18
IMHO, most could be flown into the inverted position - the prototype 707 was barrell rolled. Holding it inverted would not present too much of a problem either. Although all airliners will not be cleared for inverted flight, the structure should be able to take it.

The problem comes with feeding the engines. Of the big aircraft I have flown, only one has had a system to maintain fuel pressure under negative g - and that was a military jet.

niallcooney
21st May 2002, 21:49
As long as there's fuel pumps in your inverted Airbus, there's hope! Of course you'd have to be in Direct law... :( Passengers might get a bit grumpy too, but what the hey... they were like that when they got there! A Boeing would probably do a better job... doesn't need all those fancy systems if it can still do what the computers say it can't.

Nial

The Greaser
21st May 2002, 22:06
Sure you could fly an airliner inverted, but naturally you would be unable to maintain altitude during the manouevre.

TwinNDB
21st May 2002, 23:57
Didnt they lose an engine in that 707 when they did the roll? I can remember something about it, like pulling too many G's and one of the engines becoming 'displaced'!!! :eek:

'%MAC'
22nd May 2002, 00:33
A barrel roll, or displacement roll, is a one positive g maneuver, no harm there, except I hear in an Airbus inverted flight resets the computers. (I don’t fly the ‘bus so that is an unsubstantiated rumor.)

Transport category aircraft are not stressed for sustained negative g flight. Lots of bad things happen in a negative g environment; coffee spilling out of the pots, oil not reaching bearings, batteries leaking corrosive fluids, very limited maneuver margins, etc. Minimum maneuvering load factors are covered in 25.337 and specify only –1 g as the lower limit and +3.8 as the upper limit. It may be possible for short durations, but the stress on the engine pylons might be too much, there is a difference in pushing and pulling. Pylons designed for pushing might not hold up to pulling.

In the book Bravo Two Zero, Andy McNab writes that the transport they were on did a roll, also I have talked with sources that say the 727 does a fairly decent roll. Others would know more, but that’s my two cents.

[edited to correct homonyms, role = roll]

PAXboy
22nd May 2002, 13:34
Thansk folks, that pretty much confirms what I thought.

I can confirm that many of my fellow PAX would be grumpy even if the a/c shifted them to destination as fast as a Trek matter transporter :rolleyes:

As to the observation, "In the book Bravo Two Zero, Andy McNab writes that the transport they were on did a role [sic]." The story that Mr McNab wrote has been exposed as wildly over the top exaggeration, so am not inclined to believe him in this one either!

Dale Harris
23rd May 2002, 10:54
727 has been intentionally barrel rolled. Many years ago, by an AN captain, who shall remain nameless. Eventually he got over the *****pile it created for him!!!!!!!
Test Flight of course!!!!!!

Cornish Jack
23rd May 2002, 10:55
Dan Winterland
Did you ever come across the Sim recording of Major Fred's aero sequence in the 10 tanker? He used to offer it as an intro to new tanker course chaps.
I watched him fly an inverted ILS during one of his Sim sessions (from the console) and the trace was spot on until the flare - pulled instead of pushed ! :D The loop part of the aero sequence required much CB pulling. :D

cwatters
23rd May 2002, 21:38
> The problem comes with feeding the engines...

Nope. Feeding the passengers will be far harder.

Intruder
23rd May 2002, 22:03
The "unfeeding" of the passengers would be worse yet...