Wake vortex
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Wake vortex
Probably should go in the tech. section, but possible relevance to exam questions.
What generates most wake vortex;
A 300 ton Jumbo climbing out after take off with climb flap or
a 150 ton Jumbo in ldg. config. on approach.
What generates most wake vortex;
A 300 ton Jumbo climbing out after take off with climb flap or
a 150 ton Jumbo in ldg. config. on approach.
Both are presumably in steady flight around 1.3Vs - so generating the same proportion of induced drag.
The 300 tonner as lift =weight, and induced drag is proportional to the square of lift.
G
The 300 tonner as lift =weight, and induced drag is proportional to the square of lift.
G
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...or a B757 on the approach at 90 tonnes but with full flap deployed? The vortices off the outboard edges of the flaps are VISCOUS! and required the a/c to be re-designated 'Heavy' in that phase of flight.
TOO
TOO
The 300 tonner as lift =weight, and induced drag is proportional to the square of lift.
At the same time, new vortices are created at the edges of the flaps, thus spreading the total energy of the trailing vortices across the wingspan, rather than having it concentrated at the wingtips.
I suspect that, If it were possible to add up the energy of all the trailing vortices in the landing configuration, it would be greater than the the 'clean', or 'takeoff' case.
Perhaps the question should read:
What generates most hazardous wake vortex;
MJ
The strongest vortices ...
The strongest vortices are produced by heavy aircraft flying slowly in a clean configuration
Matches Mach Jumbīs reasoning.
jr
Last edited by janrein; 17th Sep 2015 at 08:49. Reason: typo
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Well I assumed a heavy with clean wing at low speed would produce the highest wake vortex.
But landing config. probably produces most wake turbulence due all the draggy bits out, but is that balanced out by reduced thrust?
But landing config. probably produces most wake turbulence due all the draggy bits out, but is that balanced out by reduced thrust?
In terms of total vortex strength, I'd intuitively expect the clean(er) wing to be worst as flaps move the lift distribution inboard, and reduce the pressure differential at the tips - which creates the large tip generated vortices which tend to be the major component of wake vortex power.
G
Last edited by Genghis the Engineer; 17th Sep 2015 at 21:00.
vortices off the outboard edges of the flaps are VISCOUS!
All vortices are driven by viscous fluid effects.
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Probably, but I don't suppose that he has any meaningful data about localised vorticity behind the flaps either.
Yes, I meant vicious. My bad.
TOO
Out of interest, what's the evidence that you do have ? - it's an interesting issue that must have given Boeing a hell of a headache - not unlike the one that the "Superheavy" issue gave Airbus over the A380.
G
G
