ramerinianair
Posts: 1452
Joined: Tue Nov 11, 2003 6:03 am

Wake And Stability

Thu Oct 28, 2004 10:34 am

I read quite a few threads and articles on findings about AAs incidents with their A300s. After pinning the lastest incident on the pilots, I am wondering how bad the wake was.
How much wake could the 747 cause, what/ how bad is the effect
and
How much wake can an A/C take
Thanks,
SR
W N = my Worst Nightmare!!!!!
 
User avatar
Starlionblue
Posts: 17058
Joined: Fri Feb 27, 2004 9:54 pm

RE: Wake And Stability

Thu Oct 28, 2004 11:46 pm

How much wake could the 747 cause, what/ how bad is the effect
and


Enough to flip a small aircraft and make it crash without any problems if close to the ground. This is true of all heavies and the 752.


How much wake can an A/C take

Depends on the weight, the speed and the distance.

Large aircraft are less wake sensitive, but generally you want to have at least 120 seconds separation and pilots will choose to stay out of the wake if they can of course.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Staffan
Posts: 3879
Joined: Tue Mar 18, 2008 9:21 am

RE: Wake And Stability

Fri Oct 29, 2004 12:01 am

Here are some photos showing the wake on some different a/c.

http://www.diam.unige.it/~irro/gallery.html

Staffan
 
ramerinianair
Posts: 1452
Joined: Tue Nov 11, 2003 6:03 am

RE: Wake And Stability

Fri Oct 29, 2004 4:25 am

WOW! Great guys. Thanks for the replies, the pics were really cool. Didn't realize how bad this wake could be.
SR
W N = my Worst Nightmare!!!!!
 
QantasA332
Posts: 1473
Joined: Sat Dec 13, 2003 5:47 pm

RE: Wake And Stability

Fri Oct 29, 2004 5:01 am

An aircraft's wake strength is mainly dependant on the "strength" or intensity of its wingtip vortices. As these vortices are a product of the pressure differential that keeps multi-hundred-thousand-kilo aircraft airborne, you can expect the wake to be quite strong!

Cheers,
QantasA332
 
waketurbulence
Posts: 1264
Joined: Sun Apr 18, 2004 12:33 pm

RE: Wake And Stability

Fri Oct 29, 2004 5:02 am

Several years ago the owner of In and Out Burger was in a charter jet on final for SNA behind a 752. The separation was not enough and the a/c went down about 5 miles from the runway killing all on board, the a/c that crashed was probably between 12,000 - 16,000 lbs depending on fuel. So wake can drastically affect many different types of a/c.
-Matt

Here is a pic of the type of a/c.
http://www.airliners.net/open.file/578029/L/
 
SlamClick
Posts: 9576
Joined: Sun Nov 23, 2003 7:09 am

RE: Wake And Stability

Fri Oct 29, 2004 5:51 am

It is my understanding that the separation was adequate in terms of the required time or distance. The problem was initiated by the 747 making a wide turn out and the A-300 cutting across the inside of that turn. Had it not done so, but followed the same track as the 747 the better-performing two-holer would have been above the vortices of the 747 all the way.

And yes, it can be really really bad.

I've been rolled right square upside-down at about 600' on final into LAX. I was flying a Cessna 402 at the time and the turbulence was caused by a 727. Had I known I was going to roll that far I'd have put aileron in the same direction and just gone a full roll. As it was I was fighting the roll all the way over and back.

A friend crashed in the wake of a 747. I looked at the wreckage of his Cessna 206 and I'm almost convinced that the left wing, strut, and door frame were coming off the plane before he hit the ground, torn off by the vortex. I might be wrong about this, but the wing and door frame were still a single unit with almost no other damage except having been ripped from the side of the Cessna.


Happiness is not seeing another trite Ste. Maarten photo all week long.

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