Attack angle
Thread Starter
Joined: Mar 2011
Posts: 1,407
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From: engineer at large
oh jeez......
I just need the angle of attacks at cruise...
763= 767-300
474= 747-400
738= 737-800
737= 737-700
320= 320
333= 330-300
388= 380
thanks mono, that is exactly the information I need.
I just need the angle of attacks at cruise...
763= 767-300
474= 747-400
738= 737-800
737= 737-700
320= 320
333= 330-300
388= 380
thanks mono, that is exactly the information I need.
Joined: Jun 2009
Posts: 394
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From: nowhere and everywhere
TURIN,
are you forcing yourself to look like a brain missing guy... ?
everybody understood what this guy was saying , except yourself ...?
maybe you are working for a so called company named ek ...
Genghis , this guy is a brain handiccaped person as he needs your help to make the effort to understand others ?
Hopefully , Mr @ Spotty M , wrote down all the letters and numbers for him to understand ... great team job !
are you forcing yourself to look like a brain missing guy... ?
everybody understood what this guy was saying , except yourself ...?
maybe you are working for a so called company named ek ...
Genghis , this guy is a brain handiccaped person as he needs your help to make the effort to understand others ?
Hopefully , Mr @ Spotty M , wrote down all the letters and numbers for him to understand ... great team job !
Moderator
Joined: Feb 2000
Aviation Qualifications: CPL
Posts: 14,480
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From: UK
The answers you'll get will be largely useless anyhow FlightPath because the AoAI in any given aeroplane is normally calibrated against an entirely arbitrary datum and bears only a tenuous relationship to either reality or a different aircraft type.
AoAI readings in any particular aeroplane are only really relevant to that particular aeroplane in relation to any operating data published for it.
G
AoAI readings in any particular aeroplane are only really relevant to that particular aeroplane in relation to any operating data published for it.
G
Thread Starter
Joined: Mar 2011
Posts: 1,407
Likes: 0
From: engineer at large
Genghis,
Unfortunately, I deal with a never ending supply of useless information supplied by aircraft manufacturers. I am bridging the gaps...hopefully with a reality check, for whatever reason, ignored in implementation. In gathering a broad brush of data...using the military approach to interrogation, I hope to gleen a key word here and there. If there was an straight through answer, we wouldnt be here.
I am combining ADS, RNP, GBAS, and other systems to allow the aircraft to lock in, know where each other are (aside from ATC) and self regulate..not to replace, but augment the pilot, and give the pilot the ultimate tools to do their job.
MadMax,
Books would have you believe that wings generate lift...show me a wing that generates lift an an attack angle of zero....so much for Bernoulli, how about Newton...
Unfortunately, I deal with a never ending supply of useless information supplied by aircraft manufacturers. I am bridging the gaps...hopefully with a reality check, for whatever reason, ignored in implementation. In gathering a broad brush of data...using the military approach to interrogation, I hope to gleen a key word here and there. If there was an straight through answer, we wouldnt be here.
I am combining ADS, RNP, GBAS, and other systems to allow the aircraft to lock in, know where each other are (aside from ATC) and self regulate..not to replace, but augment the pilot, and give the pilot the ultimate tools to do their job.
MadMax,
Books would have you believe that wings generate lift...show me a wing that generates lift an an attack angle of zero....so much for Bernoulli, how about Newton...
Last edited by FlightPathOBN; 3rd November 2011 at 00:38.
Joined: Feb 2002
Aviation Qualifications: AME
Posts: 4,179
Likes: 1,111
From: UK
Oh Dear!
MatMax
Yes, Some of us have to put some real effort into looking stupid.
What's your excuse?
I have never heard of either Boeing being referred to as a 37-8 or a 47-4.
So shoot me!!
Anyway this angle of attack thingy, what's that all about then?
Do enlighten us MatMax, you seem to have lots of time on your hands for insults. Why not use your vast wealth of knowledge and experience that you are so happy to heap upon us and help the man out.
Good night.
TURIN,
are you forcing yourself to look like a brain missing guy... ?
are you forcing yourself to look like a brain missing guy... ?
What's your excuse?
everybody understood what this guy was saying , except yourself ...?
So shoot me!!
maybe you are working for a so called company named ek ...
Anyway this angle of attack thingy, what's that all about then?
Do enlighten us MatMax, you seem to have lots of time on your hands for insults. Why not use your vast wealth of knowledge and experience that you are so happy to heap upon us and help the man out.
Good night.
Moderator
Joined: Feb 2000
Aviation Qualifications: CPL
Posts: 14,480
Likes: 178
From: UK
That said, I know from personal experience that many asymmetric aerofoiled aeroplanes (the C152 aerobat being an obvious example) are extremely reluctant to generate useful amounts of lift inverted - zero to negative AoA in other words. I would expect something similar from any airliner - invert it, it'll end up pitching (nose-up, world down...) into an inverted dive. Goodness only knows how much height you'd take to recover from that: a couple of tens of thousands of feet most likely.
G
Joined: Jul 2009
Posts: 1,682
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From: France - mostly
Originally Posted by FPOBN
I just need the angle of attacks at cruise...
Joined: Feb 2009
Posts: 379
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From: Seattle
Cruise AOA varies significantly
I agree completely with the reply made by HazelNuts39. Let me offer a little more explanation.
A key point that HazelNuts39 points to is the AOA reference being the fuselage. AOA is the difference between pitch attitude and flight path angle. In steady cruise flight, the passenger cabin deck angle will match the AOA. I'm sure most SLF have noticed that during cruise the front of the passenger cabin is slightly uphill when compared with the back. For long range flights, very observant SLF will note that the deck angle is greater at the beginning of cruise when the airplane is heavy (lots of fuel) vs. at the end of cruise when the airplane is lighter (not much fuel left). This will be slightly offset by increases in altitude (and thus decreases in equivalent airspeed at constant Mach number) that are typical as the cruise progresses.
A very important parameter in the design of an airplane is the relative rotation of the wing as mounted on the fuselage. With the fuselage at zero AOA, the wing could be set such that it sees positive AOA and thus generates significant lift even though the fuselage (and thus the airplane) AOA is zero. Wing rotation angle with respect to the fuselage has a significant impact on cruise drag. The best arrangement for minimum drag usually will have the cruise fuselage AOA in the neighborhood of +2 deg.
Earlier entries in this thread have suggested that zero lift occurs at an AOA that is well below 0. For most modern commercial transports the flaps up cruise zero lift AOA is very close to 0 deg. With the wing's high lift devices deployed for lower speed flight, the wing geometry usually changes such that the trailing edge is lowered, effectively rotating the wing relative to the fuselage. As a result, at landing flaps the zero lift AOA will typically be several degrees below 0. Approach and landing touchdown pitch attitude are important considerations that play into configuration definition and landing reference speed selection.
The bottom line is that cruise AOA will vary with all of the parameters that HazelNuts39 referenced above. The following changes will tend to increase cruise AOA:
- increased weight
- reduced speed
- increased altitude at a given Mach number
- more forward cg
A key point that HazelNuts39 points to is the AOA reference being the fuselage. AOA is the difference between pitch attitude and flight path angle. In steady cruise flight, the passenger cabin deck angle will match the AOA. I'm sure most SLF have noticed that during cruise the front of the passenger cabin is slightly uphill when compared with the back. For long range flights, very observant SLF will note that the deck angle is greater at the beginning of cruise when the airplane is heavy (lots of fuel) vs. at the end of cruise when the airplane is lighter (not much fuel left). This will be slightly offset by increases in altitude (and thus decreases in equivalent airspeed at constant Mach number) that are typical as the cruise progresses.
A very important parameter in the design of an airplane is the relative rotation of the wing as mounted on the fuselage. With the fuselage at zero AOA, the wing could be set such that it sees positive AOA and thus generates significant lift even though the fuselage (and thus the airplane) AOA is zero. Wing rotation angle with respect to the fuselage has a significant impact on cruise drag. The best arrangement for minimum drag usually will have the cruise fuselage AOA in the neighborhood of +2 deg.
Earlier entries in this thread have suggested that zero lift occurs at an AOA that is well below 0. For most modern commercial transports the flaps up cruise zero lift AOA is very close to 0 deg. With the wing's high lift devices deployed for lower speed flight, the wing geometry usually changes such that the trailing edge is lowered, effectively rotating the wing relative to the fuselage. As a result, at landing flaps the zero lift AOA will typically be several degrees below 0. Approach and landing touchdown pitch attitude are important considerations that play into configuration definition and landing reference speed selection.
The bottom line is that cruise AOA will vary with all of the parameters that HazelNuts39 referenced above. The following changes will tend to increase cruise AOA:
- increased weight
- reduced speed
- increased altitude at a given Mach number
- more forward cg
Joined: Jun 2008
Posts: 9
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From: Floating
Basics
It may be possible to discuss questions like these, not using terms already coined and used for decades, but you are not making it easy.
Pitch refers to relation of level to longitudinal axis.
AoA refers to relation of actual airflow to the mean aerodynamic chord, or MAC.
Flaps out gives higher AoA and slats out reduces AoA.
Pitch refers to relation of level to longitudinal axis.
AoA refers to relation of actual airflow to the mean aerodynamic chord, or MAC.
Flaps out gives higher AoA and slats out reduces AoA.
Thread Starter
Joined: Mar 2011
Posts: 1,407
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From: engineer at large
Thank you all for very helpful information and insight. There are certainly many variables, and different settings.
So with that in mind, I see that this group can likely help with my current design issue.
Currently, most everything on approach is set for a 3 or near degree GPA. The ILS, the obstacle surfaces, TCH and touchdown zone. In trajectory based management, I am finding that for many of the larger aircraft, that a 3 degree GPA causes energy management issues. I am also noting that with the advances in aerodynamics, and OPD, that the 3 degree GPA is a bit too steep, and a much flatter GPA, even down to 2.5, works much better.
Keeping to the 3 degree GPA, these differences are causing TOD issues, and energy management problems, such as speed flaps and other de-stabilizing measures, and excessive speeds on touchdown.
In efforts to optimize the trajectory, I am looking for a much better sweet spot on approach. I know that it will likely be a range of GPA's depending on the AC.
There is certainly no criteria to support this, so I am looking to the operators such as yourselves, for help, in realistic design, and perhaps new criteria. I am also looking for support on this issue, if this wont work for the aircraft and the operator, then please feel free to tell me I need to focus elsewhere, or have another beer.
So with that in mind, I see that this group can likely help with my current design issue.
Currently, most everything on approach is set for a 3 or near degree GPA. The ILS, the obstacle surfaces, TCH and touchdown zone. In trajectory based management, I am finding that for many of the larger aircraft, that a 3 degree GPA causes energy management issues. I am also noting that with the advances in aerodynamics, and OPD, that the 3 degree GPA is a bit too steep, and a much flatter GPA, even down to 2.5, works much better.
Keeping to the 3 degree GPA, these differences are causing TOD issues, and energy management problems, such as speed flaps and other de-stabilizing measures, and excessive speeds on touchdown.
In efforts to optimize the trajectory, I am looking for a much better sweet spot on approach. I know that it will likely be a range of GPA's depending on the AC.
There is certainly no criteria to support this, so I am looking to the operators such as yourselves, for help, in realistic design, and perhaps new criteria. I am also looking for support on this issue, if this wont work for the aircraft and the operator, then please feel free to tell me I need to focus elsewhere, or have another beer.
Joined: Feb 2002
Aviation Qualifications: AME
Posts: 4,179
Likes: 1,111
From: UK
At the risk of making myself look a pratt, again. Surely, a flatter GPA will result in a higher fuel burn on approach. It will also mean upsetting the neighbours as the a/c will be lower for a given distance from touch down plus engine power will have to be set higher/more noise.
Joined: Apr 2002
Posts: 274
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From: england
I tend to agree with you TURIN. We need to get into the habit of using correct unambiguous terminology. We all know what "assume" can be changed into.
Look how much devastation was caused in Tenerife all those years ago over the simple misunderstanding of the words "no" and "go". 
Look how much devastation was caused in Tenerife all those years ago over the simple misunderstanding of the words "no" and "go".
