garnetpalmetto
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757 Performance Specifications

Fri Jun 01, 2012 7:01 pm

So on another forum that I'm a member of, there's a discussion going on with a rather stubborn 9/11 "truther" type that believes UA flight 93 was shot down. A few statements made by this individual:

1) 757's dont jerk back and forth in quick, violent jerky motions. They are too large to do that. It isn't physically possible. This isn't a 2 man passenger craft we are talking about here.

The only metaphor is that a 757 handles in the air like a tank does on the ground. Its movements are very slow. Its turning radius is very large. And jerking the controls wont jerk the entire plane like you suggest.


2) I agree that is definitely possible. And for more probable for a crash landing scenario than the plane hitting in tact. It explains away a lot of the inconsistencies.

I still lean towards it being shot down though. It just makes the most sense given all the variables.

Edit: For the record, we don't even know how far it is physically possible for a plane that size to roll.

The slowness with the roll isn't because you do it carefully to avoid damage to the plane, it is because it is not physically possible to do it fast in a plane so large.


3) I find all 3 quite improbable.

Scenario 1 doesn't make sense. He'd just fly it straight into the ground. Unless he actually thought he could do a barrel roll in a 757 in some james bond like attempt to knock unconscious the attacker by dropping them on their heads. But with such a slow maneuver in a plane that large, you'd think he'd realize after 30 seconds and only tilting the jet 30 degrees that this plan wouldn't work.

Scenario 2 is improbable because a 757 doing a roll at 550+ mph is like a tank taking a 90 degree turn on a dime at 100mph. A plane that large rolling would take such a long time. I just dont see the controls being accidentally manipulated in a consistent manner for that long of a period of time during a fight. As for them being damaged, they had box cutters and fists. The controls of an aircraft are pretty sturdy. It isn't like guns were going off in there.

Scenario 3. Yeah. Unless Sarah Palin took over the controls, I don't see anyone stupid enough doing that. When a plane is going down, you pull up. You don't try to execute a barrel roll as you plummet towards the ground.

I still think scenario 4 makes the most sense.

The plane lost and engine and portion of a wing midair.


4) Planes don't accidentally barrel roll. Especially massive commercial airliners like a 757. The only way drastic maneuvers are taken is if they are forced that way by the controls. If you are flying a 757 and let go of the controls, you would barely notice a difference unless you forced the controls into a maneuver.

And a barrel roll is a complicated maneuver. Even for a small aircraft. I'm not even sold that it is physically possible for a 757. And if it is, it certainly cannot be easy and would take a lot of deliberate effort (ie forcing the controls).


Discussion in the thread begins in earnest at http://hfboards.hockeysfuture.com/showthread.php?t=1198219&page=7

I'd love for any of our more technically knowledgeable members to let me know just how much hot air this guy is blowing. Thanks!
South Carolina - too small to be its own country, too big to be a mental asylum.
 
roseflyer
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RE: 757 Performance Specifications

Fri Jun 01, 2012 7:15 pm

Well he is somewhat correct that a 757 is not a 2 person plane and that it is much smoother, but a 757 is not like a flying tank.

However I don’t think he really knows what the 757 is capable of with full flight control inputs. The 757 is a mechanically cable driven aircraft. It does not have roll rate protection like Fly By Wire airplanes have. If you put 55 degrees of control wheel input, the ailerons will deflect to 21 degrees. If you go beyond that and hit the control wheel stops at 82.5 degrees, you get spoiler deployment as well. At high speed low altitude conditions, that much aileron input is going to put the airplane into a severe roll.

In reality no pilot would ever put those roll commands into the airplane. A modern jetliner flies smoothly because pilots put very little control input in. High speed and high input will slam the 757 around. It has extremely large ailerons.

If you have someone at the controls who is panicked and not knowing what they are doing, you can get a 757 into an upset attitude and crash it. The pilots flying on 9/11 only had basic pilot skills on the 757. They knew how to turn the transponders off, basic PA communication and basic control of the airplanes, but they were not skilled pilots. They flew the airplanes outside of the normal envelope. Flying a mechanically driven airplane like the 757 is not as easy as it is shown in the movies where a flight attendant can do it. They are very stable and predictable in their flight envelope, but outside of that, if a pilot is putting full control inputs in while at high speed, it is absolutely possible that they could roll the plane right into the ground.

Don't forget that there was a pilot who got a 737 inverted and at a 145 degree angle just by rotating the rudder trim (while thinking it was the door unlock). So while a 757 won't be like a James Bond movie throwing someone to the ground, when you get into high speed roll inputs combined with elevator inputs, the airplane is hardly smooth.
If you have never designed an airplane part before, let the real designers do the work!
 
rfields5421
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RE: 757 Performance Specifications

Fri Jun 01, 2012 8:07 pm

Quoting garnetpalmetto (Thread starter):
The only metaphor is that a 757 handles in the air like a tank does on the ground.

The B757 is much more like a luxury sports sedan than a tank. It has very good control response.

Another reminder - a B707 can be put through a barrel roll. I personally would not want to try it - but I'm absolutely sure a B757 could be rolled, rather easily, if the pilot tried.

Quoting Roseflyer (Reply 1):
The pilots flying on 9/11 only had basic pilot skills on the 757.

The guys flying UA 93 would barely have been able to initiate such maneuvers in a small aerobatic aircraft if they tried. They simply didn't have the experience or training.

That is more the key to any 'unusual' movements of the aircraft. They were barely in control of the aircraft, and when attacked by the passengers, the control movements became rapid and sharp. The aircraft responded.

One final point - your 'friend' won't agree - but the US government has NEVER been that good at keeping secrets.
 
tdscanuck
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RE: 757 Performance Specifications

Fri Jun 01, 2012 9:31 pm

Quoting garnetpalmetto (Thread starter):
I'd love for any of our more technically knowledgeable members to let me know just how much hot air this guy is blowing.

A lot. We should hook him to a power plant.

For starters, airliners have very high roll rates at full deflection. The FBW ones are electronically limited and, even then, they can do about 30 degrees per second. Non-FBW aircraft can easily double that.

Airliners do jerk around in the sky; as previously posted, airliners are smooth because the pilots are smooth. If you slam the controls the airplane will get slammed. It's called a "kick" and is used during flutter testing all the time. It's extremely obvious when you do it.

And finally, all airliners (that don't have FBW stopping them) can do a barrel roll. It's a 1g maneuver. Done properly, the airplane doesn't even "see" it.

Tom.
 
OldAeroGuy
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RE: 757 Performance Specifications

Fri Jun 01, 2012 10:47 pm

Quoting garnetpalmetto (Thread starter):
Edit: For the record, we don't even know how far it is physically possible for a plane that size to roll.

The slowness with the roll isn't because you do it carefully to avoid damage to the plane, it is because it is not physically possible to do it fast in a plane so large.

To quantify some of these questions, I often participated in 757 certification flight testing.

During one stall recovery, we experienced a 70 deg bank angle.

During a handling qualities demonstrations, roll rates in excess of 60 deg per second were demonstrated.

Navy pilots flew the 757 when it was being considered as a long range patrol bomber. They were of the opinion that could hold its own in a dog fight.

Quoting garnetpalmetto (Thread starter):
Even for a small aircraft. I'm not even sold that it is physically possible for a 757. And if it is, it certainly cannot be easy and would take a lot of deliberate effort (ie forcing the controls).

During the early '50's, a Boeing test pilot did a barrel roll in the 367-80 (fore-runner to the 707) over the hydroplane races in Seattle. The -80 did fly like a tank compared to the sports car handling of the 757. In the hands of an equally skilled pilot, the 757 would have no problem performing a barrel roll.

In short, your friend is not well informed on 757 handling characteristics.

[Edited 2012-06-01 15:50:43]
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
mffoda
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RE: 757 Performance Specifications

Fri Jun 01, 2012 11:03 pm

Quoting rfields5421 (Reply 2):
One final point - your 'friend' won't agree - but the US government has NEVER been that good at keeping secrets.

Conspiracy theories, fall flat on their faces when facts are introduced... As someone who has lived in the "secret world" before... It is my experience that if more then 2 people know about it? It's Not a secret!  
harder than woodpecker lips...
 
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Stitch
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RE: 757 Performance Specifications

Sat Jun 02, 2012 3:35 am

Didn't the test pilot of the French prototype Concorde barrel roll it?
 
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Starlionblue
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RE: 757 Performance Specifications

Sat Jun 02, 2012 4:29 am

"Thanks" for making me skim through that thread. It makes me happy for the reasoned discussion among people who live in the real world we have here on a.nut...


Quoting garnetpalmetto (Thread starter):
And a barrel roll is a complicated maneuver. Even for a small aircraft. I'm not even sold that it is physically possible for a 757. And if it is, it certainly cannot be easy and would take a lot of deliberate effort (ie forcing the controls).

As others have mentioned, a barrel roll is, as aerobatic maneuvers go, neither complex nor particularly difficult.

Quoting rfields5421 (Reply 2):
One final point - your 'friend' won't agree - but the US government has NEVER been that good at keeping secrets.

Word. Except for those aliens at Roswell of course.

Quoting tdscanuck (Reply 3):
Quoting garnetpalmetto (Thread starter):
I'd love for any of our more technically knowledgeable members to let me know just how much hot air this guy is blowing.

A lot. We should hook him to a power plant.

              

Quoting tdscanuck (Reply 3):
Airliners do jerk around in the sky; as previously posted, airliners are smooth because the pilots are smooth. If you slam the controls the airplane will get slammed. It's called a "kick" and is used during flutter testing all the time. It's extremely obvious when you do it.

I had a demonstration recently. On climbout from SGN our 330 went from take-off power to climb power with a hell of a jolt. The whole plane shook and reverberated. I was looking at the left wing and it was flapping all over the place for a second or so. I can only conclude that the pilot flying decreased throttle a mite less gently than he should have. So yes, planes can jerk...

[Edited 2012-06-01 21:34:53]
"There are no stupid questions, but there are a lot of inquisitive idiots."
 
Max Q
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RE: 757 Performance Specifications

Sat Jun 02, 2012 5:12 am

Quoting OldAeroGuy (Reply 4):


Navy pilots flew the 757 when it was being considered as a long range patrol bomber. They were of the opinion that could hold its own in a dog fight.

With what, a B52 ?!


I have to call Bs on this one


Seriously, if they said that they must have been pulling your leg !



I have flown the 757 and 767 for fifteen years and I can tell you beyond a shadow of a doubt they are hardly 'dogfighters'




Good responsive Aircraft, yes (more so the 767 actually) but nothing beyond that.
The best contribution to safety is a competent Pilot.
 
rfields5421
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RE: 757 Performance Specifications

Sat Jun 02, 2012 1:11 pm

Quoting Max Q (Reply 8):
With what, a B52 ?!

An IL-38, or Tu-95 - the aircraft into which a long range patrol aircraft would be most likely engaged against. Though the possibility of going up against a long ranger fighter does exist. The goal isn't to dogfight and shoot down the enemy aircraft, but to be able to evade enough to survive.

Our EC-121's on occasion had to try to avoid fighter aircraft. One did, one did not. One of our EP-3E aircraft survived a mid-air collision with a fighter.

But the point is moot because rather than the B757, the Navy decided on the P-8A - a version of the B737.

I assume the B757 is more nimble than the B737, simply based on power of the engines.
 
OldAeroGuy
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RE: 757 Performance Specifications

Sat Jun 02, 2012 2:14 pm

[quote=Max Q,reply=8]Quoting OldAeroGuy (Reply 4):

Navy pilots flew the 757 when it was being considered as a long range patrol bomber. They were of the opinion that could hold its own in a dog fight.
With what, a B52 ?!


I have to call Bs on this one


Seriously, if they said that they must have been pulling your leg ![/quote

Then you've never seen the P-3's armed with Sidewinders?

http://www.bing.com/images/search?q=...=0&qpvt=P-3+Sidewinder&FORM=IDFRIR

Also this article.

http://www.p3orion.nl/sneaky.html

Navy pilots will dogfight with any airplane they fly. The 757 would fly rings around a P-3, the airplane they would have been replacing.

And don't be so quick to dismiss the B-52. At its design attack altitudes and weights, it could turn inside a Mig-17. Low wing loading does have it's advantages. There was a reason that the B-52 had a tail gun.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
CM
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RE: 757 Performance Specifications

Sat Jun 02, 2012 3:27 pm

Quoting OldAeroGuy (Reply 10):
Navy pilots will dogfight with any airplane they fly.

A pilot will always "dance with who they brung". They have little choice.

Quoting Max Q (Reply 8):
I have flown the 757 and 767 for fifteen years and I can tell you beyond a shadow of a doubt they are hardly 'dogfighters'

Dogfight may not have been the best choice of words, but...

As far as large transport aircraft are concerned, you could do much worse than a 757: no artificial limits on control authority and a better power to weight ratio than other comparable aircraft. Certainly compared to other maritime patrols, the 757 would have fared pretty well.

http://www.youtube.com/watch?v=fYZOB...lU&feature=player_detailpage#t=11s
 
Max Q
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RE: 757 Performance Specifications

Sun Jun 03, 2012 4:59 am

Quoting OldAeroGuy (Reply 10):
Then you've never seen the P-3's armed with Sidewinders?

You could put Sidewinders on a DC3, so what ?

Quoting OldAeroGuy (Reply 10):




Navy pilots will dogfight with any airplane they fly. The 757 would fly rings around a P-3, the airplane they would have been replacing.

Since we are continuing to discuss the ridiculous, why would you assume that anyway ?


Although, your statement (unintentionally) is probably true, a 757 would fly large rings around a P3, not being able to fly nearly as slow and turn as tightly.

Quoting CM (Reply 11):
A pilot will always "dance with who they brung". They have little choice.

What does this even mean ?

Quoting CM (Reply 11):


As far as large transport aircraft are concerned, you could do much worse than a 757: no artificial limits on control authority and a better power to weight ratio than other comparable aircraft. Certainly compared to other maritime patrols, the 757 would have fared pretty well.

Not sure how many hours you have actually flying a 757 but in terms of handling you can do a lot better, the 767, is far more responsive, as was the B727.



A dogfighting 757 ! only on A. net...

[Edited 2012-06-02 22:00:13]
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tdscanuck
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RE: 757 Performance Specifications

Sun Jun 03, 2012 4:40 pm

Quoting Max Q (Reply 12):
A dogfighting 757 ! only on A. net...

And the US Navy. But let's not let reality get in the way of the discussion.

Tom.
 
roseflyer
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RE: 757 Performance Specifications

Sun Jun 03, 2012 8:11 pm

Quoting Max Q (Reply 12):
Not sure how many hours you have actually flying a 757 but in terms of handling you can do a lot better, the 767, is far more responsive, as was the B727.

With both ailerons the 767 is more manuverable but am not sure about high speed when the outboard aileron is locked out. As you would know as a pilot the 757/767 are more capable of erratic flight maneuvers than most other planes. The a320 a330 a340 777 and 787 all have roll rate limitations. I think that was his point. I think he was only talking roll rate too since as far as I know there are not pitch rate limitations.
If you have never designed an airplane part before, let the real designers do the work!
 
CM
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RE: 757 Performance Specifications

Sun Jun 03, 2012 8:13 pm

Quoting Max Q (Reply 12):
What does this even mean ?

It means it does not matter whether you are in a P-3, or an MR2 Nimrod, (or a 757, for the sake of this discussion), if these aircraft are engaged by an enemy aircraft, the pilot has no choice but to meet that engagement in the aircraft they are flying in.

Aircraft such as the Nimrod have at times been outfitted with offensive air-to-air armament, so the underlying premise that no maritime patrol aircraft would ever be involved in an air-to-air combat is simply wrong.
 
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Starlionblue
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RE: 757 Performance Specifications

Mon Jun 04, 2012 2:51 am

Going back to the original point. While a 757 might not be able to out-turn an F-16, it can certainly move in an erratic and jerky fashion.

A 757 can also pull way more Gs than pax are likely to experience. If memory serves, a 330 can pull 2.5G positive and 1G negative before needing an inspection. I imagine a 757 would be similar. With typical 50% margin, this means it will withstand at least 3.75G positive and 1.5G negative.

As for roll, the 747-100 can, with gear down and full flap go from 30 degree roll to one side all the way to 30 degree roll to the other side without using rudder in 4.8 seconds*. This includes the time to accelerate into the roll from a stable fixed angle. Note again this is with gear and full flaps. That's a way larger aicraft than a 757.

Bottom line, airliners can maneuver way more nimbly than the flying public imagines. They aren't flown this way because airlines don't like their pax puking all over the place and soiling their pants with fear.



* "Source: Handling the Big Jets" - Davies
"There are no stupid questions, but there are a lot of inquisitive idiots."
 
CM
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RE: 757 Performance Specifications

Mon Jun 04, 2012 3:08 am

Quoting Starlionblue (Reply 16):
They aren't flown this way because airlines don't like their pax puking all over the place and soiling their pants with fear.

Thanks for the compelling visual! 
 
Max Q
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RE: 757 Performance Specifications

Tue Jun 05, 2012 5:53 am

Quoting tdscanuck (Reply 13):

And the US Navy. But let's not let reality get in the way of the discussion.

Don't you have a single engine ferry to do Tom ? !
The best contribution to safety is a competent Pilot.
 
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Starlionblue
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RE: 757 Performance Specifications

Tue Jun 05, 2012 7:36 am

Quoting Max Q (Reply 18):
Don't you have a single engine ferry to do Tom ? !

Interestingly, single engine take-offs on a two engine aircraft are mentioned as having been done in "Handling the Big Jets" by Davies, a very respected book in the industry. Davies does refer to them as "circus tricks" but still.

  
"There are no stupid questions, but there are a lot of inquisitive idiots."
 
tdscanuck
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RE: 757 Performance Specifications

Tue Jun 05, 2012 9:45 pm

Quoting Starlionblue (Reply 16):
A 757 can also pull way more Gs than pax are likely to experience. If memory serves, a 330 can pull 2.5G positive and 1G negative before needing an inspection. I imagine a 757 would be similar. With typical 50% margin, this means it will withstand at least 3.75G positive and 1.5G negative.

Don't forget the g-limits are all at relatively high weight...if you're light you go higher (same absolute force, higher g).

Tom.
 
OldAeroGuy
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RE: 757 Performance Specifications

Wed Jun 06, 2012 3:58 pm

Quoting tdscanuck (Reply 20):
Quoting Starlionblue (Reply 16):
A 757 can also pull way more Gs than pax are likely to experience. If memory serves, a 330 can pull 2.5G positive and 1G negative before needing an inspection. I imagine a 757 would be similar. With typical 50% margin, this means it will withstand at least 3.75G positive and 1.5G negative.

Don't forget the g-limits are all at relatively high weight...if you're light you go higher (same absolute force, higher g).

Tom.

Also depends on how the load is distributed. Low ZFW with Empty Center Tank and Full Main Tanks gives you even more potential capability.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
Max Q
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RE: 757 Performance Specifications

Thu Jun 07, 2012 1:37 am

I stand corrected, apparently the new 'Top Gun' movie will have Maverick in the left seat of a 757 (no replacement for Goose yet)



There are some gripping action scenes 'turning and burning' with Tupolev's and Ilyushin's.



As he say's: 'you can't think up there, if you think you're dead'
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prebennorholm
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RE: 757 Performance Specifications

Fri Jun 08, 2012 1:45 am

Quoting Starlionblue (Reply 16):
A 757 can also pull way more Gs than pax are likely to experience. If memory serves, a 330 can pull 2.5G positive and 1G negative before needing an inspection. I imagine a 757 would be similar. With typical 50% margin, this means it will withstand at least 3.75G positive and 1.5G negative.

Indeed the 757 is similar, or rather identical.

2.5G + 50% = 3.75G is "ultimate load" which any airliner wing has to withstand during a static test for certification. Those +50% is a safety margin which also shall compensate for "aging", such as beginning corrosion, minor fatigue cracks, a few loose rivets, and production irregularities etc. No airliner shall ever exceed 2.5G in ops, or it shall be inspected.

Example: 22 January 2002 a 757 experienced an unstabilized approach into OSL due to pilot error. It was put into an 49 deg. dive, then pulled up (leveling off at 321 ft. radio altitude!!!) to a 40 deg. climb while experiencing a G load of 3.59 - and an overspeed. It was put through a C-check, and a special "overload inspection".

From the report:
In February 2002, after the incident, the aircraft went through a C-check. When Boeing became aware of the seriousness of the incident, the company requested [the airline co.] to perform a very extensive structural inspection on the airplane. The inspection was focused on the fuselage, wings, empennage and the engine strut connection. The inspection asked to look for distortion, flaked paint, cracks, and buckled structure and for fasteners that have pulled out or “are not there”. The inspection was very detailed, and required many of the inspection tasks that already had been accomplished during the above-mentioned C-check. The Boeing Company sent a wing structure engineer specialist to assist with determining possible damage, and to determine if further inspection would be required. It turned out that a re-inspection of the parts that had been inspected during the C-check was not necessary. As a result of this, the extent of the inspection decreased. It was apparent that the airplane’s structure had not been damaged. As a precaution, the following parts were exchanged:

1. Six fuse bolts in the engine strut connection
2. The forward bolts on the flap track to wing connection
3. The two bolts that run through the two main rollers, on each flap track.


It was pretty lightweight, only 75 pax and normal fuel for landing. That helped a lot. But in any case, exceed 2.5G, and you are in great trouble after handing in your FDR data.
Always keep your number of landings equal to your number of take-offs
 
Max Q
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RE: 757 Performance Specifications

Fri Jun 08, 2012 3:17 am

Quoting prebennorholm (Reply 23):

From the report:
In February 2002, after the incident, the aircraft went through a C-check. When Boeing became aware of the seriousness of the incident, the company requested [the airline co.] to perform a very extensive structural inspection on the airplane. The inspection was focused on the fuselage, wings, empennage and the engine strut connection. The inspection asked to look for distortion, flaked paint, cracks, and buckled structure and for fasteners that have pulled out or “are not there”. The inspection was very detailed, and required many of the inspection tasks that already had been accomplished during the above-mentioned C-check. The Boeing Company sent a wing structure engineer specialist to assist with determining possible damage, and to determine if further inspection would be required. It turned out that a re-inspection of the parts that had been inspected during the C-check was not necessary. As a result of this, the extent of the inspection decreased. It was apparent that the airplane’s structure had not been damaged. As a precaution, the following parts were exchanged:

Impressive, but typical for Boeing and all the more reason why we should start a rapid and unprecedented replacement of all front line jet fighters with 757's.



Think of the savings, not to mention the publicity for Boeing..
The best contribution to safety is a competent Pilot.
 
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Starlionblue
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RE: 757 Performance Specifications

Fri Jun 08, 2012 7:01 am

Quoting prebennorholm (Reply 23):
22 January 2002 a 757 experienced an unstabilized approach into OSL due to pilot error. It was put into an 49 deg. dive, then pulled up (leveling off at 321 ft. radio altitude!!!) to a 40 deg. climb while experiencing a G load of 3.59 - and an overspeed. It was put through a C-check, and a special "overload inspection".

The report on the incident is fascinating reading. After the botched approach, overstressed aircraft and possible instrument malfunction on approach, the captain elected to continue with the next leg to Stockholm!!! In fact the aircraft continued operating until 25 January, when it was (apparently) due for a C-check...

http://911research.wtc7.net/cache/pe...sis/theories/aaib_757incident.html

[Edited 2012-06-08 00:01:56]
"There are no stupid questions, but there are a lot of inquisitive idiots."
 
Legs
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RE: 757 Performance Specifications

Fri Jun 08, 2012 9:25 am

Quoting Max Q (Reply 22):
'Top Gun' movie will have Maverick in the left seat of a 757

One of the more impressive airshow displays I've ever seen was an RNZAF 757 at the Avalon Airshow several years ago. I can only guess bank angles and the like, but I wouldn't be surprised if they were around 50 degrees or more, as well as doing a rapid rollout to a very big pitch up over the runway. Of course, Im sure the plane was configured just as OldAeroGuy said, but very, very impressive nonetheless.
 
Max Q
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RE: 757 Performance Specifications

Fri Jun 08, 2012 11:59 pm

Quoting legs (Reply 26):

One of the more impressive airshow displays I've ever seen was an RNZAF 757 at the Avalon Airshow several years ago. I can only guess bank angles and the like, but I wouldn't be surprised if they were around 50 degrees or more, as well as doing a rapid rollout to a very big pitch up over the runway. Of course, Im sure the plane was configured just as OldAeroGuy said, but very, very impressive nonetheless.

It was an impressive display but meaningless really. So he made a high speed pass and a very steep climb out, you could do the same with a lightweight 747 or any transport category jet, it's just energy management.


It doesn't make it a fighter..
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CM
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RE: 757 Performance Specifications

Sat Jun 09, 2012 1:07 am

Quoting Max Q (Reply 8):
I can tell you beyond a shadow of a doubt they are hardly 'dogfighters'
Quoting Max Q (Reply 24):
we should start a rapid and unprecedented replacement of all front line jet fighters with 757's.
Quoting Max Q (Reply 27):
It doesn't make it a fighter..

You've changed the argument a bit I'd say. You are the only one arguing about the 757 being a fighter. In fact, no one on this thread has brought up the 757 being a fighter except you. The original comment which set you off was...

Quoting OldAeroGuy (Reply 4):
Navy pilots flew the 757 when it was being considered as a long range patrol bomber. They were of the opinion that could hold its own in a dog fight.

He was making the point it was agile enough to compare favorably with other long-range patrol bombers. No aircraft in this role is "agile" in the same way a fighter is. But then again nobody here has claimed the 757 is agile like a fighter, so I'm not sure why you are arguing it is not.

The 757 is agile as far as large commercial platforms go. It has higher pitch and roll rates than most commercial jets, and has no control protections which would limit a pilot from achieving the full aerodynamic performance of the aircraft. In this sense, it was not a bad candidate as a commercial platform for this military application. Nobody is saying anything more than this.

At this point, you have twisted the point others were trying to make and are vigorously arguing against a position that no one here is advocating. Namely that the 757 would make a good fighter aircraft. We agree! The 757 would make a terrible fighter aircraft. Let it go.
 
Max Q
Posts: 5628
Joined: Wed May 09, 2001 12:40 pm

RE: 757 Performance Specifications

Sat Jun 09, 2012 6:39 am

Quoting CM (Reply 28):

You've changed the argument a bit I'd say. You are the only one arguing about the 757 being a fighter. In fact, no one on this thread has brought up the 757 being a fighter except you. The original comment which set you off was...

I have been attempting (in vain apparently) with logic and my own brand of humour to point out what a ridiculous concept a 'dogfighting 757' is in any scenario.




A previous poster quoted a Navy Pilot as claiming it could 'hold it's own in a dogfight'



I am still calling BS on this !

Quoting CM (Reply 28):

He was making the point it was agile enough to compare favorably with other long-range patrol bombers. No aircraft in this role is "agile" in the same way a fighter is. But then again nobody here has claimed the 757 is agile like a fighter, so I'm not sure why you are arguing it is not.


The 757 is agile as far as large commercial platforms go. It has higher pitch and roll rates than most commercial jets, and has no control protections which would limit a pilot from achieving the full aerodynamic performance of the aircraft. In this sense, it was not a bad candidate as a commercial platform for this military application. Nobody is saying anything more than this.

I'm quite familiar with the 757 as I have been flying it for the last 15 years ! I don't know how much time you have flying this Aircraft (I would venture to say zero) and it is not the most responsive airframe anyway.



The 767 has a better roll rate with four Ailerons versus two and is more responsive in pitch.



The 727 had better handling than the 757, as above it was more responsive.



I'm not knocking the Aircraft but it's attributes tend to get exaggerated here just because it has a healthy power to weight ratio !



Anyway I thought my 'Top Gun 2' Analogy was quite funny..
The best contribution to safety is a competent Pilot.
 
CM
Posts: 623
Joined: Wed Feb 08, 2012 4:17 am

RE: 757 Performance Specifications

Sat Jun 09, 2012 4:24 pm

Quoting Max Q (Reply 29):
it is not the most responsive airframe anyway.

You're still changing the argument. No one claimed the 757 was the most responsive airframe out there. What was claimed is the 757 is a very agile airplane, and it is. Let's compare it to the A321 as these are two comparably sized aircraft:

The A321 is limited to 13 degrees per second of roll rate. The 757 has aileron authority which delivers greater than 25 degrees per second roll rate.

The A321 is limited to 67 degrees bank angle clean and 60 degrees with a dirty wing. The 757 can roll without bank angle limits.

The A321 is limited in pitch angle (-15 degrees/+25 degrees). The 757 has no limits on pitch angle.

As noted in the thread above, the A321 is limited in load factor to -1g/+2.5g. The 757 is not limited in load factor and in fact has demonstrated in service the ability to pull more g's than the airplane is certified for (something which appears to have saved the airplane from becoming a lawn ornament).

Is the 757 the most responsive commercial jet in the world? No. And no one has claimed that. Getting back to my original point...

Quoting CM (Reply 28):
The 757 is agile as far as large commercial platforms go.

...this in fact is true, even if you have found another commercial jet which is more agile.

Quoting Max Q (Reply 29):
I don't know how much time you have flying this Aircraft (I would venture to say zero)

You are correct. I am a pilot, but I have zero hours in the 757 or 767. If this was your attempt to somehow discredit the point I was making, your logic is lost on me. I was a part of the team that designed the 757-300 and know an awful lot more about the airplane than the average guy who has been trained to sit in the pointy end.

Anyhow, if you want to dispute my comment on its technical merits, by all means, let's have that conversation. If you simply want to say you are the only person qualified to comment on the capability of the airplane because you have a 757 type stamped on your ticket, then you are sadly delusional about the importance of pilots or the knowledge gained from 20 days of training and 15 years of driving an airplane in 1G flight from point A to point B.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: 757 Performance Specifications

Sat Jun 09, 2012 7:35 pm

Quoting Max Q (Reply 29):
A previous poster quoted a Navy Pilot as claiming it could 'hold it's own in a dogfight'

I am still calling BS on this !

That's fine, but why are you calling BS on it on a.net...shouldn't you be calling BS with the Navy? Don't blame CM for something that someone else said.

Tom.
 
Max Q
Posts: 5628
Joined: Wed May 09, 2001 12:40 pm

RE: 757 Performance Specifications

Sat Jun 09, 2012 8:59 pm

Quoting tdscanuck (Reply 31):

That's fine, but why are you calling BS on it on a.net...shouldn't you be calling BS with the Navy? Don't blame CM for something that someone else said.

Er Tom, this is a discussion forum, thats why.
The best contribution to safety is a competent Pilot.
 
Max Q
Posts: 5628
Joined: Wed May 09, 2001 12:40 pm

RE: 757 Performance Specifications

Sat Jun 09, 2012 9:03 pm

Quoting CM (Reply 30):
You are correct. I am a pilot, but I have zero hours in the 757 or 767. If this was your attempt to somehow discredit the point I was making, your logic is lost on me

If you cannot see how real experience operating an Aircraft has relevance to a discussion on it's maneuverability your credibility is in serious doubt !
The best contribution to safety is a competent Pilot.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: 757 Performance Specifications

Sat Jun 09, 2012 9:40 pm

Quoting Max Q (Reply 33):
If you cannot see how real experience operating an Aircraft has relevance to a discussion on it's maneuverability

Real experience operating an airliner in line service won't come anywhere close to hitting the maneuverability limits unless you've done something very strange. As a result, the fact that someone has flown a 757, by itself, provides no particular qualification on commenting on maneuverability, especially when going against someone who knows what the actual maneuverability limits are.

Now, if you *have* hit the maneuverability limits, that's certainly germane but that's a completely separate thing (and probably a great story we'd all like to hear) from just having flown the aircraft.

Tom.
 
CM
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RE: 757 Performance Specifications

Sat Jun 09, 2012 9:43 pm

Quoting Max Q (Reply 33):
If you cannot see how real experience operating an Aircraft has relevance to a discussion on it's maneuverability your credibility is in serious doubt !

I know with 100% certainty you have never flown the 757 anywhere near the limits of it's aerodynamic performance. Your ticket and your employer both prohibit it. With the exception of a handful of OEM test pilots, engineers always know more about the full performance of an aircraft than a line pilot.

I drive a 5-series. I don't pretend to know more about its performance than the people who designed it. Driving it as a cab every day for the next 15 years wouldn't change anything. I would still have never experienced the full performance capability of the car.

Sadly, we're far afield of the original point, which was...

Quoting garnetpalmetto (Thread starter):
757's dont jerk back and forth in quick, violent jerky motions. They are too large to do that. It isn't physically possible. This isn't a 2 man passenger craft we are talking about here.

Something which is simply not true. The 757 is very capable of maneuvers extreme enough to feel very "jerky" and uncomfortable to a passenger.
 
Max Q
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Joined: Wed May 09, 2001 12:40 pm

RE: 757 Performance Specifications

Sun Jun 10, 2012 6:11 am

Quoting tdscanuck (Reply 34):

Real experience operating an airliner in line service won't come anywhere close to hitting the maneuverability limits unless you've done something very strange. As a result, the fact that someone has flown a 757, by itself, provides no particular qualification on commenting on maneuverability, especially when going against someone who knows what the actual maneuverability limits are.

What complete nonsense Tom.



You are now claiming that a person that knows the published limits of an Aircraft by reading about them has more authority on it's operation and handling qualities than someone with extensive experience actually flying it .



It does show the gaping chasm in your knowledge between your position monitoring those involved in flight testing and the Pilots who actually fly these Aircraft day in, day out around the world in all different kinds of weather and situations who occasionally do operate these machines to the limits of their capability.



You simply wouldn't know as you haven't done it

Quoting CM (Reply 35):

I know with 100% certainty you have never flown the 757 anywhere near the limits of it's aerodynamic performance.

It is truly fascinating how sure you can be of something with which you have no first hand knowledge.




Get yourself all the certificates required , the thousands of hours and jump through all the hoops to get hired as a Pilot by a major Airline (if you are good enough) get through all the tests, experience requirements and pay the dues required to get to the right seat, let alone the left of a 757.



Than accumulate several thousand hours of experience flying it in the real world.




After that, your opinion on its handling qualities might have some validity.



Not just what you read in a book..




Another Armchair expert !
The best contribution to safety is a competent Pilot.
 
XaraB
Posts: 117
Joined: Fri Aug 17, 2007 9:23 pm

RE: 757 Performance Specifications

Sun Jun 10, 2012 7:38 am

Quoting Max Q (Reply 36):

You are now claiming that a person that knows the published limits of an Aircraft by reading about them has more authority on it's operation and handling qualities than someone with extensive experience actually flying it .

Not reading about; *designing*. There's a slight difference in knowledge level between the two.

Quoting Max Q (Reply 36):
It does show the gaping chasm in your knowledge between your position monitoring those involved in flight testing and the Pilots who actually fly these Aircraft day in, day out around the world in all different kinds of weather and situations who occasionally do operate these machines to the limits of their capability.

Note that the *entire purpose* of an extensive test regime is to ensure that a product functions flawlessly and safely within its entire performance capabilities/limits. Of course, this means testing the product to extremes it will *never* encounter in real life, to ensure a proper safety margin. This applies to consumer goods, fireproofing, armor, you name it.
Which is why you see:
- Wings being tested and certified to destruction, at a minimum of 150% of Maximum design load.
- Planes brought to full stall and VNE during final testing
- Production cars "flooded" after assembly, to check for cabin leaks
- Offshore safety valves tested at 110-120% of maximum design pressure
- Fire-proofing (insulation, lining, barriers) are subject to intense direct gas-fueled fires for a number of minutes far higher than the response time of an emergency unit, with very stringent requirements for maximum allowed temperatures.
And I could go on... Only in cases where a product is designed to *always* perform right at its limit (such as race cars) is there extensive cooperation between driver, designers and engineers to achieve an optimal mix of performance characteristics and safety. Civilian airliners are not such products, fighter aircraft are.

Quoting Max Q (Reply 36):
Get yourself all the certificates required , the thousands of hours and jump through all the hoops to get hired as a Pilot by a major Airline (if you are good enough) get through all the tests, experience requirements and pay the dues required to get to the right seat, let alone the left of a 757.



Than accumulate several thousand hours of experience flying it in the real world.




After that, your opinion on its handling qualities might have some validity.

Obviously you are proud of your lifetime achievements, and rightly so. That doesn't automatically translate into a justification to ignore anyone with a different approach to the same field of expertise. I'm an engineer by trade, and our teams always achieve the best results (in every dicipline) when the different experts are open to inputs from other diciplines.
Example: A Structural Engineer might be an expert in how to best design a steel structure to withstand the highest possible load. However, his efforts are meaningless unless he embraces the Material Engineer's knowledge of microstructures and -properties of the steel qualities, corrosion characteristics and manufacturing methods applied. And both their efforts are meaningless if they end up with a design that is not certifiable or possibly unsafe; for that, they need the Safety Engineer.

Quoting Max Q (Reply 36):
Another Armchair expert !

Hardly.
You've taken on a plane tester and a plane designer, both with significantly higher respect ratings than yourself. Apparently their knowledge (and willingness to share it) is greatly valued by the formidable mix of amateurs, enthusiasts and professionals that frequent these forums. You are able to know where the limits to your workplace are because people like them *told* you what the limits are, when they wrote the operating manuals for the 757. And they know because they (respectively) designed and verified (by testing) these limits way before any line pilot got his hands on the aircraft.

[Edited 2012-06-10 00:43:02]
An open mind is not an empty one
 
Max Q
Posts: 5628
Joined: Wed May 09, 2001 12:40 pm

RE: 757 Performance Specifications

Sun Jun 10, 2012 7:57 am

Quoting XaraB (Reply 37):

Not reading about; *designing*. There's a slight difference in knowledge level between the two.
Quoting XaraB (Reply 37):

Note that the *entire purpose* of an extensive test regime is to ensure that a product functions flawlessly and safely within its entire performance capabilities/limits. Of course, this means testing the product to extremes it will *never* encounter in real life, to ensure a proper safety margin. This applies to consumer goods, fireproofing, armor, you name it.
Which is why you see:
- Wings being tested and certified to destruction, at a minimum of 150% of Maximum design load.
- Planes brought to full stall and VNE during final testing
- Production cars "flooded" after assembly, to check for cabin leaks
- Offshore safety valves tested at 110-120% of maximum design pressure
- Fire-proofing (insulation, lining, barriers) are subject to intense direct gas-fueled fires for a number of minutes far higher than the response time of an emergency unit, with very stringent requirements for maximum allowed temperatures.
And I could go on... Only in cases where a product is designed to *always* perform right at its limit (such as race cars) is there extensive cooperation between driver, designers and engineers to achieve an optimal mix of performance characteristics and safety. Civilian airliners are not such products, fighter aircraft are.
Quoting XaraB (Reply 37):

Obviously you are proud of your lifetime achievements, and rightly so. That doesn't automatically translate into a justification to ignore anyone with a different approach to the same field of expertise. I'm an engineer by trade, and our teams always achieve the best results (in every dicipline) when the different experts are open to inputs from other diciplines.
Example: A Structural Engineer might be an expert in how to best design a steel structure to withstand the highest possible load. However, his efforts are meaningless unless he embraces the Material Engineer's knowledge of microstructures and -properties of the steel qualities, corrosion characteristics and manufacturing methods applied. And both their efforts are meaningless if they end up with a design that is not certifiable or possibly unsafe; for that, they need the Safety Engineer.
Quoting XaraB (Reply 37):

You've taken on a plane tester and a plane designer, both with significantly higher respect ratings than yourself. Apparently their knowledge (and willingness to share it) is greatly valued by the formidable mix of amateurs, enthusiasts and professionals that frequent these forums. You are able to know where the limits to your workplace are because people like them *told* you what the limits are, when they wrote the operating manuals for the 757. And they know because they (respectively) designed and verified (by testing) these limits way before any line pilot got his hands on the aircraft.

So what ?


Both of these 'plane testers' and 'plane designers' have no actual experience flying their 'product' as actual Pilots.



But, as you say, their 'respect ratings' are higher so that completely makes up for their total lack of real world Jet transport Pilot experience..



Perhaps the Airlines should start hiring future Pilot candidates using these ratings and, perhaps how much Microsoft flight sim experience one has accumulated..



Think of the savings..


Time to return to reality.
The best contribution to safety is a competent Pilot.
 
XaraB
Posts: 117
Joined: Fri Aug 17, 2007 9:23 pm

RE: 757 Performance Specifications

Sun Jun 10, 2012 8:26 am

Quoting Max Q (Reply 38):

Way to miss the point...

Which of the following statements are true?
1. I drive a Toyota Prius, and I know way better than Toyota what the car is capable of doing.
2. I own a gas barbecue, and I know way better than its certifier how much abuse it can take before it blows up.
3. I am an astronaut, and I know way better than the rocket/shuttle designer what the craft is capable of doing.
4. I drive trains for a living, and I know way better than the track engineers what the rails can sustain before they break.
5. I have ridden rollercoasters for 40 years, and I know way better than their designers how close to their limits they are operating.
6. I have been SCUBA diving for 20 years, and I know way better than the tank manufacturer what it can take before breaking.
7. I am a policeman, and I know way better than any gun manufacturer what their pieces can handle.
8. I am a parent, and I know way better than the hospital what makes my kids healthier.
An open mind is not an empty one
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: 757 Performance Specifications

Sun Jun 10, 2012 1:43 pm

Quoting Max Q (Reply 36):
You are now claiming that a person that knows the published limits of an Aircraft by reading about them has more authority on it's operation and handling qualities than someone with extensive experience actually flying it .

Not exactly. I'm claiming that people who designed and executed the flight maneuvers that gave you the published limits have more authority on those limits than someone who's read them (e.g. in the AFM) but never actually seen them.

Quoting Max Q (Reply 36):
It does show the gaping chasm in your knowledge between your position monitoring those involved in flight testing and the Pilots who actually fly these Aircraft day in, day out around the world in all different kinds of weather and situations who occasionally do operate these machines to the limits of their capability.

Really? You've taken a 757 to the limit of it's capability vis a vis maneuvering? I'd honestly love to hear that story.

Quoting Max Q (Reply 38):
Both of these 'plane testers' and 'plane designers' have no actual experience flying their 'product' as actual Pilots.

I'm not sure why you keep assuming that. I can't speak for CM but, in my case at least, it's not true.

Quoting Max Q (Reply 38):
But, as you say, their 'respect ratings' are higher so that completely makes up for their total lack of real world Jet transport Pilot experience..

Again, not sure why you keep assuming that. I don't have an ATPL (and I don't think CM does but I'm not sure about that). That's not quite the same thing has "total lack of real world jet transport pilot experience."

Tom.
 
Max Q
Posts: 5628
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RE: 757 Performance Specifications

Sun Jun 10, 2012 9:57 pm

Fact is real experience counts.




While this fact may be troubling to some of you it is extremely valuable in real life.




When Pilots are hired to work for any operation, but especially a Major Airline, their real life experience, in addition to their certificates and other qualifications are carefully reviewed.



These substantiated qualifications are valued more highly than their's or someone else's ability to recite the maneuvering limits of a particular Aircraft.




Reading the limits out of a book, or even providing these limits through aerodynamic analysis is not the same.



Similarly, a Pilot, who operates a particular model of Aircraft and has accumulated significant experience on it has the real life experience to comment on it's handling qualities and compare it to other models because he or she has actually flown it.





They get to know it's handling qualities, it's eccentricities, strengths and weaknesses, with their real life experience they can take advantage of the strengths and compensate for the weaknesses.




Their opinions are simply the most accurate with respect to Aircraft handling qualities.




No matter how much Microsoft flight sim you have played or how high your respect rating on an internet site
The best contribution to safety is a competent Pilot.
 
XaraB
Posts: 117
Joined: Fri Aug 17, 2007 9:23 pm

RE: 757 Performance Specifications

Sun Jun 10, 2012 10:23 pm

Quoting Max Q (Reply 43):
Similarly, a Pilot, who operates a particular model of Aircraft and has accumulated significant experience on it has the real life experience to comment on it's handling qualities and compare it to other models because he or she has actually flown it.

No doubt about that. Within the normal operating envelope.

Quoting Max Q (Reply 43):
Their opinions are simply the most accurate with respect to Aircraft handling qualities.

Possibly; again within the normal operating envelope.

Do you think that it was coincidence that a Boeing Test Pilot rolled the 707 successfully, or that any airline pilot with a few years in that airplane could have pulled off that manouvre?
An open mind is not an empty one
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: 757 Performance Specifications

Sun Jun 10, 2012 11:02 pm

Quoting Max Q (Reply 43):
Reading the limits out of a book, or even providing these limits through aerodynamic analysis is not the same.

Let's lay our cards on the table here. Do you know what your airplane will do with a full step wheel input? Full step rudder? Full step column? At a variety of speeds and altitudes?

Because I do. Not because I've read it from a book, not because I've done the analysis, but because 1) I've been in the flight deck while we've done it, with far more instrumentation that a line crew has access too, 2) I've got access to all the test data (which isn't in any published information available to line pilots), and 3) doing my job safety depends on knowing the answers to all those questions. And, despite what you probably think, I'm very good at my job.

Tom.

[Edited 2012-06-10 16:02:50]
 
CM
Posts: 623
Joined: Wed Feb 08, 2012 4:17 am

RE: 757 Performance Specifications

Sun Jun 10, 2012 11:29 pm

Quoting Max Q (Reply 36):
accumulate several thousand hours of experience flying it in the real world. After that, your opinion on its handling qualities might have some validity.

Interesting. The handling qualities you have learned about through experience are the deliberate product of a design. This includes handling qualities way out to the very edges of the flight envelope... the areas where if you had flown a 757 to, we would all be able to read about it as it would be a truly extraordinary incident. Even what you have called the "eccentricities", "strengths" and "weaknesses" were in most cases known long before any pilot ever flew the 757. What you call an "eccentricity", a designer may tell you is a change in column force intended to help you avoid a PIO from a quick push-over maneuver. Like the capability of the airplane itself, the handling you experience on a daily basis, even the quirks, is something which was designed into the airplane.

Before the first flight of a new type, the test pilots work very closely with engineers to understand how the airplane will handle in flight. This handling is modeled into the simulators, based on the engineering definition. Since I have been in this industry (since the late 1980s), test pilots always are amazed after the first flight of an airplane at how accurately engineers have simulated the handling qualities of a new airplane in the cab, long before it has ever flown. These things don't happen by chance. Tom and the test pilots are simply going out to substantiate with testing what we already know through engineering analysis.

If you get nothing else from all of this, get this: Handling qualities are not an accidental byproduct of the airplane which can only be understood by building and then flying an airplane. They are the very deliberate outcome of one of the most exacting sciences in the aviation industry.

Quoting Max Q (Reply 36):
Not just what you read in a book..

The handling qualities of an airplane are known by its designers long before they are ever published in a book.

Quoting Max Q (Reply 43):
Their [airline pilots'] opinions are simply the most accurate with respect to Aircraft handling qualities.

I am sure you truly believe this. A am equally certain it is entirely incorrect.

Quoting tdscanuck (Reply 41):
I don't have an ATPL (and I don't think CM does but I'm not sure about that).

Nope. Nothing commercial on my ticket. When I fly, it's just for fun

Quoting Max Q (Reply 36):
Another Armchair expert !

Actually, there's nothing "armchair" about it; I get up each morning and design airplanes professionally. I am in fact a real expert - as in recognized across the industry as such. Odds are I have spoken to pilots at your airline by request of your company because of it. Anyhow, I'm not sure why you feel so certain someone who designs airplanes as a profession would actually understand very little about them.

Quoting Max Q (Reply 43):
No matter how much Microsoft flight sim you have played

Never have used it, but I hear it is quite good!  

[Edited 2012-06-10 16:39:37]
 
bond007
Posts: 4423
Joined: Mon Mar 14, 2005 2:07 am

RE: 757 Performance Specifications

Mon Jun 11, 2012 2:26 am

Quoting Max Q (Reply 43):
Fact is real experience counts.

Yep, real experience of test flying airliners counts, of which I assume you have none.

If this was a thread about flying an airliner from MIA to PHL, and we wanted to know all about ... you'd probably be the expert ... but it isn't!

Jimbo
I'd rather be on the ground wishing I was in the air, than in the air wishing I was on the ground!
 
Max Q
Posts: 5628
Joined: Wed May 09, 2001 12:40 pm

RE: 757 Performance Specifications

Mon Jun 11, 2012 4:08 am

Quoting tdscanuck (Reply 45):

Let's lay our cards on the table here. Do you know what your airplane will do with a full step wheel input? Full step rudder? Full step column? At a variety of speeds and altitudes?


With a full Aileron input the Aircraft will roll until I stop it by rolling in the opposite direction. With a full Rudder input the Aircraft will yaw initially followed by yaw induced roll. With a full elevator input upward the Aircraft will pitch up,, if no further input is made this will eventually result in an aerodynamic stall. Conversely with a pitch down the Aircraft will nose over eventually exceeding VMO / MMO if no further input is made. I do not know the precise numbers associated with any of these maneuvers but I am not a Test Pilot of course neither are you.

Quoting tdscanuck (Reply 45):




Because I do. Not because I've read it from a book, not because I've done the analysis, but because 1) I've been in the flight deck while we've done it,


Not the same as actually flying it.


with far more instrumentation that a line crew has access too, 2) I've got access to all the test data (which isn't in any published information available to line pilots), and 3) doing my job safety depends on knowing the answers to all those questions. And, despite what you probably think, I'm very good at my job.

You may be, I don't know, you do have some very odd opinions on what would be acceptable in the real world of jet transport flying, the most obvious being your adamant opinion that a twin engine jet could be ferried legally on one engine, despite all available evidence to the contrary. More bewildering than that was your incomprehension as to how this could present any hazard !




What you are, is an expert spectator. Not the same as a Test Pilot or an experienced Jet transport Pilot.



You may find this very difficult to accept, but it is not the same.



Real Pilot handling experience counts.

Quoting CM (Reply 46):
Handling qualities are not an accidental byproduct of the airplane which can only be understood by building and then flying an airplane

I disagree, if this was the case why would you need a flight test program ?



My experience and that of my peers show otherwise. Besides this is not a mutually exclusive analysis. Handling qualities may be and are built in, verified and 'tweaked' by Test Pilots but it is the line Pilot that takes this Aircraft and operates it all over the world in all different kinds of conditions.



This real life experience, outside of the carefully controlled test flight program will provide the line Pilot with an unprecedented exposure to the Aircraft's handling qualities and boost his or her own competence as a result.

Quoting CM (Reply 46):



Quoting Max Q (Reply 43):
Their [airline pilots'] opinions are simply the most accurate with respect to Aircraft handling qualities.

I am sure you truly believe this. A am equally certain it is entirely incorrect.







Test Pilots will put the Aircraft through all manner of evolutions to discover it's handling qualities, performance, unexpected surprises etc but then they will move on. While their expertise in this area is unquestioned competence in flying comes through experience and currency.



A test Pilot will not fly one model of Aircraft year after year and for thousands of hours, an Airline Pilot does, Wadrs
CM if you were an Airline Pilot you would know how important experience and currency are, why do you think currency requirements are mandated by Civil Aviation Authorities world wide ?

Quoting CM (Reply 46):

Actually, there's nothing "armchair" about it; I get up each morning and design airplanes professionally. I am in fact a real expert - as in recognized across the industry as such. Odds are I have spoken to pilots at your airline by request of your company because of it. Anyhow, I'm not sure why you feel so certain someone who designs airplanes as a profession would actually understand very little about them.

You very well may be, I did not say you did not understand the theories involved in designing Jet Transport Aircraft or, indeed how they work.




What you lack, as does Tds is real world experience actually flying them.




There is simply no substitute.

[Edited 2012-06-10 21:10:22]

[Edited 2012-06-10 21:38:01]

[Edited 2012-06-10 22:09:07]
The best contribution to safety is a competent Pilot.
 
CM
Posts: 623
Joined: Wed Feb 08, 2012 4:17 am

RE: 757 Performance Specifications

Mon Jun 11, 2012 5:06 am

Quoting Max Q (Reply 48):
I disagree, if this was the case why would you need a flight test program ?

I hinted at this above, but I'll spell it out more clearly. Aircraft are certified via engineering analysis. Testing (including flight testing) is done to validate the engineering analysis. There are a few exceptions to this, where the published limits of an aircraft are restricted to what's been physically demonstrated (like crosswind landings), but for the vast majority of certification points, the aircraft is certified by analysis and testing is done to demonstrate the integrity of that analysis. To try to certify based purely on testing would be impractical and costly to the point of making it a non-starter.
 
Max Q
Posts: 5628
Joined: Wed May 09, 2001 12:40 pm

RE: 757 Performance Specifications

Mon Jun 11, 2012 5:14 am

Quoting CM (Reply 49):

I hinted at this above, but I'll spell it out more clearly. Aircraft are certified via engineering analysis. Testing (including flight testing) is done to validate the engineering analysis. There are a few exceptions to this, where the published limits of an aircraft are restricted to what's been physically demonstrated (like crosswind landings), but for the vast majority of certification points, the aircraft is certified by analysis and testing is done to demonstrate the integrity of that analysis. To try to certify based purely on testing would be impractical and costly to the point of making it a non-starter.

I agree, the engineering analysis is enormously important.



The flight test program should validate the design and this analysis. My point was and is that there are still unexpected surprises in flight test and this is precisely what it is for.
The best contribution to safety is a competent Pilot.
 
tdscanuck
Posts: 8572
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RE: 757 Performance Specifications

Mon Jun 11, 2012 12:43 pm

Quoting Max Q (Reply 48):
I do not know the precise numbers associated with any of these maneuvers but I am not a Test Pilot of course neither are you.

That was exactly the point. I do know the precise numbers (and the qualitative look and feel of all of them when you actually do it). No line pilot does.

Quoting Max Q (Reply 48):
you do have some very odd opinions on what would be acceptable in the real world of jet transport flying, the most obvious being your adamant opinion that a twin engine jet could be ferried legally on one engine, despite all available evidence to the contrary.

You mean despite the statement from the FAA that it has been done? Or are we just forgetting that?

Quoting Max Q (Reply 48):
What you are, is an expert spectator. Not the same as a Test Pilot or an experienced Jet transport Pilot.

Absolutely true. But the question is what situation is better to comment on handling capability...I don't see the argument that someone who's never experienced the full envelope can comment better about what the full envelope is like than someone who has.

Quoting Max Q (Reply 48):
You may find this very difficult to accept, but it is not the same.

I don't find it at all difficult to accept. I agree, it is not the same. But we disagree on which experience base is more relevant to the topic at hand.

Quoting Max Q (Reply 48):
Quoting CM (Reply 46):
Handling qualities are not an accidental byproduct of the airplane which can only be understood by building and then flying an airplane

I disagree, if this was the case why would you need a flight test program ?

CM let you off easy with a very short and succinct answer.

Quoting Max Q (Reply 48):
My experience and that of my peers show otherwise. Besides this is not a mutually exclusive analysis. Handling qualities may be and are built in, verified and 'tweaked' by Test Pilots but it is the line Pilot that takes this Aircraft and operates it all over the world in all different kinds of conditions.

The "all different kinds of conditions" that a line pilot experiences are a subset of what the test pilots do (by design). A line pilot should never, and can never legally except in a true emergency, reach the conditions the test pilot does.

Quoting Max Q (Reply 48):
This real life experience, outside of the carefully controlled test flight program will provide the line Pilot with an unprecedented exposure to the Aircraft's handling qualities

How? The test envelope is bigger than the line envelope, and the test pilots very explicitely cover the entire envelope.

Quoting Max Q (Reply 48):
A test Pilot will not fly one model of Aircraft year after year and for thousands of hours

Yes, they will and do.

Quoting Max Q (Reply 50):
The flight test program should validate the design and this analysis. My point was and is that there are still unexpected surprises in flight test and this is precisely what it is for.

That is *a* reason for flight test (although not the biggest one). But it has nothing to do with knowing the true handling capability of a 757.

Tom.

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