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Thread ID: 126294 2012-08-19 00:56:00 Flight question FoxyMX (5) PC World Chat
Post ID Timestamp Content User
1295421 2012-08-19 00:56:00 Since the forum has quite a few pilots and plane enthusiasts perhaps someone can answer a question I have.

If a passenger plane similar to and the size of our national JetStar planes had just taken off and was banking to the left to turn, how far could its wing dip down before it got into trouble and fell out of the sky? 		FoxyMX (5)
1295422 2012-08-19 01:07:00 I'm not a pilot but have spent a fair amount of time on Flight Simulator over the years. So what I have to say may not make any real sense at all.

I would think that the maximum 'bank angle' for a plane such as a 737 or A320 would be in the region of 30 degrees, but just after takeoff I'd say that turns would be limited to say 15 degrees as the plane is ascending at the same time and things would be a wee bit more crucial.

The 'wee bit' description is not necessarily approved technical jargon - however if you hear the pilot say that we are in a wee bit of ****, be worried.

Edit: Here's a link on the question too, but it's not talking about "just after takeoff angle"

www.airliners.net 		Jester (13)
1295423 2012-08-19 01:39:00 The bank angle is related to the "g" force regardless of the type of plane, so for the comfort of passengers, and safe "g" structural loadings maximum bank angle would be around 30 degrees.

It is explained simply here: www.petester.com 		Terry Porritt (14)
1295424 2012-08-19 01:43:00 It largely depends on the air turbulence and the aircraft's airspeed at the time. The aircraft bank angle causes the wing loading to increase; this basically makes the air work harder to increase the apparent weight being supported, turbulence can increase the loads too. If the loading exceeds a figure (which varies with the airspeed) the airflow over the top of the wing will become turbulent rather than smooth and the available lift is markedly reduced as the wing "stalls".
So, it depends on the load, the speed, the lift enhancing devices in use (flaps, leading edge slats), and turbulence. If the bank is excessive the pilot may cease to have a dry seat, but normal operation has rather wide safety margins to allow the variables plenty of range. 		R2x1 (4628)
1295425 2012-08-19 01:49:00 It is Dependant on speed, attitude and bank angle as well as loading. Lets say at a typical climb of 15 degrees we roll to the left, as we do so gravity pulls the plane sideways. Because of the whacking great vertical stabiliser (tail) causing resistance, the plane, if left to it's on devices will turn nose down into the turn. To counter this in normal operation, opposite rudder is applied to keep the nose up. If the plane is too slow, or has an imbalanced load pilot error could cause a disaster (because the plane would not react normally). But they are trained not to let that happen (Pre flights ensure you know your maneuver speeds and tolerances)

Here is a beautiful (yet tragic) demonstration of a C130 model having the exact problem you described www.youtube.com Insufficient airspeed caused flight control surfaces to become unresponsive. Not sure but i'd presume that the flaps were still down and a lack of airspeed caused this crash. 		The Error Guy (14052)
1295426 2012-08-19 01:50:00 Cheers guys. I can't find my protractor so will just have to guess where 30 degrees is. :p

Notwithstanding passenger comfort I am interested in how far they can go if the pilot or plane "accidentally" banked too far, for instance was banking five minutes after take off then the wing dipped down almost vertical for a second or two. :eek:

The plane didn't fall out of the sky but I am interested to know if it *could* if it had dipped a few degrees more? All the passengers got a huge fright, as one would expect. :stare:


Edit: Just read The Error Guy's post and viewed the video. Can see how that plane crashed but the one I am referring to was on a much more vertical climb than that and probably going faster which probably saved it. Still, I think it was pretty lucky that it didn't come to any grief. 		FoxyMX (5)
1295427 2012-08-19 02:03:00 There would be too many variables to give an answer, as the others have indicated in their replies, particularly as the problem is not a "steady state" one.

When a plane barrel rolls the wings go through vertical, but the plane doesn't fall out of the sky :) 		Terry Porritt (14)
1295428 2012-08-19 02:05:00 For a momentary bank, it can get quite extreme for a short while with no harm, but if it is a sustained bank angle things get a bit complex. if it is just momentarily "dipped" by turbulence, it could conceivably go beyond a right angle without any great structural loading on the aircraft. Cups of tea etc. might make their own arrangements though. R2x1 (4628)
1295429 2012-08-19 02:09:00 Well in a little aircraft you could bank at 45 deg or even 60. It is not unheard of that a commercial airliner could go into a roll and they rescued it. Nomad (952)
1295430 2012-08-19 04:50:00 2 Bobs worth. Lift is a force vertical to the wing, and opposing gravity, which in level flight is also vertical to the wing. Flight happens because lift exceeds gravity. It is at this point that the plane has reached V2 at take-off, and the pilot knows he is at lift off speed.
If you tilt the wing the lift remains vertical to the wing, but at an increasing angle to gravity. therefore you are reaching a state where if the wing is upside down the plane would fall out of the sky if other forces weren't brought into play. A plane flying inverted has all its control surfaces in the same position as a plane flying straight and level but into a forced descent. Planes can only perform aerobatics such as steep turns and loops and inverted flight, if they have sufficient airspeed. Too slow, and they will again stall and fall out of the sky. Modern airliners are fitted with computer controls that will not let the pilot carry out any manoeuver which is outside the aircraft's safety envelope. 		Richard (739)
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