Cutlass1287
Well-Known Member
Ok, so we all know that B757 wake is nothing to mess around with, but does anybody know why?
Wake Turbulence
- Thread starter Cutlass1287
- Start date
G
Guest
Guest
Not really related to the question but thanks Alex. I'll take the quiz at ASF as soon as I finish reading AIM 7-45. I actually tought wake turbulance came from the engines and not the wings. Thanks for explaining!
Maximilian_Jenius
Super User
(raises hand...)
The reason that the 757 wing creates so much wake turbulance is like lain said the design of the wing.
The 757's wing is swept at 25 degrees so it isn't a terribly fast wing but not necessarily slow either.
Correct me if I'm wrong slower wings create more lift then higher swept wings which have to move faster throught the air to create lift.
A by product of lift is drag and wing vorticies. Also a plane creates more WT when it is low,slow and heavy.
Boeing created the 757 to replace the 727 as well all know so it has STOL capability as well as high lift devices.
Due to the 757 wing sweep I have been told that it can produce more WT then other largers heavies.
This info was told to me by a 757 driver when I worked the ramp at CVG.
Maybe A300capt might be able to comment on it and possibly correct me if I'm wrong as he used to fly 757/767's.
Matthew
The reason that the 757 wing creates so much wake turbulance is like lain said the design of the wing.
The 757's wing is swept at 25 degrees so it isn't a terribly fast wing but not necessarily slow either.
Correct me if I'm wrong slower wings create more lift then higher swept wings which have to move faster throught the air to create lift.
A by product of lift is drag and wing vorticies. Also a plane creates more WT when it is low,slow and heavy.
Boeing created the 757 to replace the 727 as well all know so it has STOL capability as well as high lift devices.
Due to the 757 wing sweep I have been told that it can produce more WT then other largers heavies.
This info was told to me by a 757 driver when I worked the ramp at CVG.
Maybe A300capt might be able to comment on it and possibly correct me if I'm wrong as he used to fly 757/767's.
Matthew
flyover
New Member
The 757 got a bad rep because it was not quite a heavy so ATC was using regular spacing. But the 757 is close to heavy weight and ithey finally started giving more spacing behind it.
Honestly I have followed a lot of 757s and everything else on approach. The airpplane that has consistently given me the worst wake problems is the 737.
Honestly I have followed a lot of 757s and everything else on approach. The airpplane that has consistently given me the worst wake problems is the 737.
FalconCapt
New Member
[ QUOTE ]
Here too. The 737-800 will rock your world during takeoff.
[/ QUOTE ]
Not if you're outclimbing it!
Here too. The 737-800 will rock your world during takeoff.
[/ QUOTE ]
Not if you're outclimbing it!
A300Capt
Freight Dawg
Don't know exactly why the B757 produces such a strong wake. You'll have to ask a Boeing engineer...I just drive the dang thing.
Seriously, the B757 was designed with a new, very clean and very efficient, high lift wing. It's even a clean design when it's all dirtied up for landing.
Boeing tends to over design the wings allowing them to stretch one model without having to design a whole other wing. Case in point, the B757-200 and the new 757-300 share the same wing.
The worst wake I ever hit was from a USAir BAC One-Eleven back in my commuter days going into PIT. It turned my ity-bity Metroliner every which way but loose on short final.
Seriously, the B757 was designed with a new, very clean and very efficient, high lift wing. It's even a clean design when it's all dirtied up for landing.
Boeing tends to over design the wings allowing them to stretch one model without having to design a whole other wing. Case in point, the B757-200 and the new 757-300 share the same wing.
The worst wake I ever hit was from a USAir BAC One-Eleven back in my commuter days going into PIT. It turned my ity-bity Metroliner every which way but loose on short final.
A300Capt
Freight Dawg
[ QUOTE ]
Showoff!
[/ QUOTE ]
Speaking of "show-offs". As we were getting beat up in the Mid-west flying around T'storms last week at FL310, we had some corporate jet-jockey check in at FL470! Doesn't he know you could get a nose bleed up there so high?!?
Bet his ride was smooth!
Showoff!
[/ QUOTE ]
Speaking of "show-offs". As we were getting beat up in the Mid-west flying around T'storms last week at FL310, we had some corporate jet-jockey check in at FL470! Doesn't he know you could get a nose bleed up there so high?!?
Jeff_S_KDTW
New Member
[ QUOTE ]
You know what was weird about the -90 was that it'd do a commendable job until about FL200, but between FL200 and FL230, it was an absolute dog, but then it'd pick up nicely again thru FL230.
[/ QUOTE ]Why is that, Doug??
You know what was weird about the -90 was that it'd do a commendable job until about FL200, but between FL200 and FL230, it was an absolute dog, but then it'd pick up nicely again thru FL230.
[/ QUOTE ]Why is that, Doug??
Maximilian_Jenius
Super User
Doug is it maybe because the wing of the 80/90 series MD is so short?
So I'm at work the other day in Tempe and I have a window near the approach/dept. area of KPHX.
I happened to look out the window and see a CO 737-900 on final to rwy 25R.
All that I could say was daaaaaaaaamn that thing was huge.
Matthew
So I'm at work the other day in Tempe and I have a window near the approach/dept. area of KPHX.
I happened to look out the window and see a CO 737-900 on final to rwy 25R.
All that I could say was daaaaaaaaamn that thing was huge.
Matthew
seagull
Well-Known Member
As I recall, the 757 issue had more to do with the design of the flaps, where they extend as pretty much one section. The other aircraft in the size class have flaps in a couple of sections so it breaks up the flow. As a result, the 757 has wake more like an aircraft about twice its weight. It also is pretty close to the old "heavy" limit without going over, so that may have been some factor, but not that much of one. The heaviest of the 727s is over 200k, and most of the other heavies are more than 500k.
Without knowing more, I'd venture that the -90 climb performance that Doug mentioned is more related to Delta's climb speed schedule than anything else...
Without knowing more, I'd venture that the -90 climb performance that Doug mentioned is more related to Delta's climb speed schedule than anything else...
flyover
New Member
[ QUOTE ]
Hmmm, do different types of MD-80s and 737s possess entirely different climb characteristics?
From what I can recall it always used to be that the 737 could jump climb a MD-80 any day. At least it always seems to happen that way on my ATC simulations!!!!!
[/ QUOTE ]
The -200 and -300 models are short takeoff roll, fast climbers. They were designed for that. The -800 is a different animal.
Why the -80s are such good inital climbers I don't know. But I flew it for 8 years and then the -800 and the -80s consistently outcimb the -800s, at least for the first 4-5,000 feet or so.
Hmmm, do different types of MD-80s and 737s possess entirely different climb characteristics?
From what I can recall it always used to be that the 737 could jump climb a MD-80 any day. At least it always seems to happen that way on my ATC simulations!!!!!
[/ QUOTE ]
The -200 and -300 models are short takeoff roll, fast climbers. They were designed for that. The -800 is a different animal.
Why the -80s are such good inital climbers I don't know. But I flew it for 8 years and then the -800 and the -80s consistently outcimb the -800s, at least for the first 4-5,000 feet or so.