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Thrust on during flare...Q for AIRBUS test pilots...

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Thrust on during flare...Q for AIRBUS test pilots...

Old 25th Mar 2014, 12:55
  #41 (permalink)  
 
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Well I hope he is tongue in cheek Bloggs but I suspect he's serious......
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Old 25th Mar 2014, 13:03
  #42 (permalink)  
 
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Well, we all knew how this discussion always ends, didn't we….

You are correct, it is Magenta. I am sure you will forgive my spelling mistake.

But it is flying principles we are discussing here, not your personal achievements.

So, pitch for path in your….. A330 it was……?
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Old 25th Mar 2014, 13:04
  #43 (permalink)  
 
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Yep in the 330 and the 777 I flew and the 744 and the 737 and the F50.

It was different in the Helo I flew, but then again I only did 1 hour in it..... great fun, you should try it young fella.

Do you have a big watch?
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Old 25th Mar 2014, 13:08
  #44 (permalink)  
 
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Seems to be some confusion between Boeing And Airbus guys.

A Boeing is speedstable, thus pitch controls speed. Add thrust nose comes up, decrease thrust nose comes down, as the aircraft is trimmed for speed.

An Airbus, files very different in normal law. Add thrust, pitch stays the same thus speed increases. Decrease thrust, pitch stays the same and speed reduces.

Anyway thrust + pitch = performance in all aircraft.
You can fly the aircraft in a fixed pitch attitude and use thrust to arrest the rate of descent until touchdown.
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Old 25th Mar 2014, 13:14
  #45 (permalink)  
 
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737 Jock---It's not as simple as that. On the 777 it does trim for speed BUT the FBW compensates for configuration AND power changes.... So in effect on approach it won't pitch up if you increase thrust. The 737 and 744 would pitch up. Either way Boeing instructors teach Thrust for speed and Pitch for path control.

What you are describing is secondary effect.

Yes power + attitude equals performance. Thus would be true no matter which way you do it.


The Airbus FBW logic goes one step further in normal law and maintains a G. Great In theory but it does move in practice!!

The flying techniques used in both are the same as taught by Boeing and Airbus.
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Old 25th Mar 2014, 13:16
  #46 (permalink)  
 
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I never needed to add power.
Blatant lie!

Sorry but that's the biggest bunch of BS I have ever heard. There is no such thing as NEVER and ALWAYS in aviation.
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Old 25th Mar 2014, 13:21
  #47 (permalink)  
 
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The flying techniques used in both are the same as taught by Boeing and Airbus.
The flying techniques are just that techniques. Thrust and pitch are linked, cause what we want to fly is performance.
It doesn't matter one bit what you change first. It's just an easy way to teach students and give them some good concepts to quickly deal with matters. But it is as easy as I said.

But I bet your ass that when you feel a kick in your back due to a gust you immediately reduce thrust, which in a Boeing will automatically lower the nose due to it being trimmed for speed. You know this you have this experience, a student might actually lower the nose (increasing speed) and then reduce thrust to reduce speed. No experienced pilot would do this.
In an airbus you will immediately take thrust off and lower the nose with the sidestick to maintain speed.

Can't believe professional pilots are discussing this.
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Old 25th Mar 2014, 13:28
  #48 (permalink)  
 
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If I get a sudden positive shear causing the a/c to ballon high I will immediatly lower the nose to keep the path AND reduce thrust to check the speed. All within acceptable limits depending on the altitude above the runway. ( We don't want to go shoving the nose forward at low levels!!! )

This has happened in all the types I've flown including the A330, you might think it won't change the pitch but it does.

I agree though, you do both at the same time to achieve the performance result. But you must get the basics correct in your head first.

I'll say it again, the 777 isn't only trimmed for speed, the FBW compensates for configuration AND thrust changes. Nice piece of kit and to my mind way way better than the A330.

Last edited by nitpicker330; 25th Mar 2014 at 13:41.
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Old 25th Mar 2014, 13:41
  #49 (permalink)  
 
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The guy still insists that he pitches for path in a 777 and a 747.

Ok

By the way, we are discussing handling the aircraft yourself, not on AP that compensates blah blah blah through FBW or whatever.

Try manual flight and see if your theory works. Don't forget to pitch for your path now……...
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Old 25th Mar 2014, 13:42
  #50 (permalink)  
 
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Ok noodle guy I give up.

I'm going to leave now, you can play with other guys in here.

Happy trails and fly safe ( as they say )
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Old 25th Mar 2014, 13:50
  #51 (permalink)  
 
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Can you just grasp the simple fact that pitch + power is performance?
Or that Power + Pitch = performance

It doesn't matter which one gets changed first.

Outside factors influence what performance is needed to fly the desired path and speed. You have 2 tools to achieve this pitch and power, and they consistently interact with each other no matter what aircraft you fly or which fancy computer Boeing or Airbus came up with this time.

I never said pitch doesn't change.

But you apparently want to make a big point about the following 3 options which happen to be exactly the same:
1. Pitch down then reduce thrust = less performance
2. Reduce thrust then pitch down = less performance
3. Pitch down and reduce thrust simultaneously = less performance

Except that example 2 in a Boeing the thrust reduction will cause an automatic lowering of the nose (it is trimmed for speed, less thrust causes speed reduction thus nose lowers to increase speed and vertical speed increases (no gusts)). So less pilot input needed.
The only thing that we fix in our aircraft is the speed we fly at. And that dictates our pitch and thrust changes.

Whereas in an Airbus it doesn't matter one bit which sequence you chose.
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Old 25th Mar 2014, 14:07
  #52 (permalink)  
 
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Originally Posted by 737 Jock
You can fly the aircraft in a fixed pitch attitude and use thrust to arrest the rate of descent until touchdown.
Hmm. Well, you can, but... How's the speed going to reduce from Vapp to Vref for the touchdown if you're increasing power to arrest the descent? Not what the 737 FCTM says.

Originally Posted by Noodle
Flare needs depend on a thousand different factors.
No, only two: sink rate and speed reduction. That's all. You still haven't actually told us how you land, Noodles. You just keep pointing the stick and at the flare point jam on some power? Or do you pull the stick back to reduce the speed and put the power up to reduce the descent rate? What do you do when it says "Retard"?

But you apparently want to make a big point about the following 3 options which happen to be exactly the same:
Picker's and my point is you use the primary effects of controls to control the aeroplane. That's all. If you're low on slope, pull the stick back to get back on it pronto. If necessary, adjust the thrust to maintain or regain the speed. Just like the AP and autothrottle does on an ILS. If you're on the glidselope and slow, you don't push the nose down...do you?? Don't use the secondary effects of controls to control the aeroplane.

Last edited by Capn Bloggs; 25th Mar 2014 at 14:20.
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Old 25th Mar 2014, 14:14
  #53 (permalink)  
 
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It's just to illustrate the point that pitch + power = performance. And end this stupid discussion if power is speed or path and pitch is speed or path. They both are speed and path, as they determine the performance together.
Nor would I like to fly an approach with a fixed pitch setting, to many power changes.

And anyway I bet you have no idea what your actual speed is during the flare, you just know it's reducing and approximately ok as you were at Vapp when you started your flare.

That's why we add factors on top of the in factored landing distance which is based on Vref.
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Old 25th Mar 2014, 14:15
  #54 (permalink)  
 
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The reason you pitch up is to bleed off excess speed during flare.
So how much speed do you actually lose during flare? Is it significant? If you wouldn't flare, what would most likely be the result? A runway overrun?

Maybe next time you land on a long runway, so a few knots more doesn't matter, why not try to land without flaring to see what happens? If flaring is only for speed reduction, it shouldn't matter?
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Old 25th Mar 2014, 14:28
  #55 (permalink)  
 
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And end this stupid discussion if power is speed or path and pitch is speed or path.
Actually, I don't think it is a stupid discussion. You and I can fly satisfactorily using our own techniques (dunno about Noodles) but throw a newby in the seat and tell them to use thrust to control the slope and the stick to control the speed and they'd be in all sorts of bother. I certainly don't tell my FOs to do that. If they try, I growl at them. I've seen to many near-splats with the nose still down and the thrust up all because we fell into a bit of a hole. Pull the friggin' stick back a bit, Bloggs!
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Old 25th Mar 2014, 14:43
  #56 (permalink)  
 
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Large Airplanes

Pilots of larger airplanes with higher stall speeds may find the speed they maintain on the instrument approach is near

1.3 VSO, putting them near point C (in figure 2-7) the entire time the airplane is on the final approach segment. In this case, precise speed control is necessary throughout the approach. It may be necessary to overpower or underpower in relation to the target power setting in order to quickly correct for airspeed deviations.

For example, a pilot is on an instrument approach at 1.3 VSO, a speed near L/DMAX, and knows that a certain power setting will maintain that speed. The airplane slows several knots below the desired speed because of a slight reduction in the power setting. The pilot increases the power slightly, and the airplane begins to accelerate, but at a slow rate. Because the airplane is still in the “flat part” of the drag curve, this slight increase in power will not cause a rapid return to the desired speed. The pilot may need to increase the power higher than normally needed to maintain the new speed, allow the airplane to accelerate, then reduce the power to the setting that will maintain the desired speed.

One of the more difficult tasks that a pilot must routinely execute occurs during the brief transition between the final approach and first contact with the landing surface. This transition is known as the landing flare. The flare process requires that the pilot adjust the aircraft attitude and power settings from those maintained during final approach to values which are appropriate for landing. To be successful, these adjustments must occur at a height above the landing surface that will vary based on the size, weight and performance criteria of the aircraft and the prevailing environmental conditions. In many aircraft, pilots are required to make all height assessments based solely on external visual clues. A radio altimeter, when fitted, will provide an accurate height above the runway and can aid the pilot in determining the appropriate point at which to initiate the flare.
If executed correctly, the flare will result in the aircraft achieving the appropriate landing attitude with power at or near idle, a reduced rate of descent and a decaying airspeed, all at a height varying from several inches to several feet above the landing surface (dependant upon aircraft type). If not executed correctly, the flare could result in a hard landing, the collapse of the landing gear, a tailstrike or in a runway overrun or excursion.
Flare technique, and the amount of time prior to touchdown that the aircraft is maintained in the landing attitude to allow the speed to decay, varies from aircraft to aircraft. At one end of the spectrum are landings on an aircraft carrier in which the aircraft maintains the approach attitude and rate of descent until touchdown. For all intents, there is no flare and the landing gear design must be robust enough to ensure that no damage occurs because of the high rate of descent. At the other extreme are many light, general aviation, aircraft in which proper landing technique requires that the aircraft be held off the runway in the landing attitude until the speed decays almost to the point of aerodynamic stall. The majority of aircraft fall in between these extremes with touchdown occurring after the flare, power reduction and a brief hold off, at a speed well above Vs. Note that for these aircraft, intentionally holding the aircraft off of the runway for a protracted period in an attempt to achieve a smooth touchdown will result in a significant increase in landing distance and could lead to a tailstrike.
Once the main landing gear is in contact with the runway, de-rotation should occur without delay and before decaying airspeed results in the loss of elevator authority. In all cases, appropriate roll out and deceleration procedures should be initiated immediately following the touchdown as dictated by the calculated stopping distance and the available runway.


Enjoy willy fighting...
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Old 25th Mar 2014, 14:45
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Just to throw it in there:

B747, Japan, 1985-ish. Phugoid motions ended in worst single air crash ever.

DC10, Sioux City, 1989-ish. Phugoid motions ended in not-too-bad-landing.

A3x0, Baghdad, 2002-ish. Phugoid motions but pilots managed to land it.

What goes first in phugoid motions?

Why do you get a phugoid motion?

How were the successful landings managed?

Why was it possible to get successful landings?

Depending on the answers, you would know which pilot to trust with such a scenario.
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Old 25th Mar 2014, 14:53
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Bloggs, it is evident that you are not an experienced jet pilot. Spare us the stories of "your FOs"….

You rely too much on quotes from the FCTM and you exhibit a typical weak personality trait, trying to be a part of a team or a bigger group of people with the same opinion ( "Picker and I" "all of us" etc).

Why is it so important for you to be at Vref during touchdown? What do these speeds mean to you? Do you comprehend the real meaning behind these reference numbers?
Can your aircraft touch down without floating at Vref +30 or +40?

I repeat, you are using a wrong technique, it doesn't mean it doesn't work, just means that you are not actually "flying" the plane all the way to touchdown.
Flaring the way you describe it, translates into touching down whenever the aircraft feels like it, not where you want it. Read my posts more carefully to see the details, try it next time, and you will see that there is no floating, no hard landing, and most of all exact spot landing.

Its not for everyone. Boeing in the manuals, describes a simplistic technique that assures the company does not get in any legal trouble from possible misinterpretations.
Manuals are written with a team of lawyers over the pilots' shoulders.
Boeing instructors, technical pilots, test pilots and other experienced pilots will instruct you more complex details, only able to be shown while at the controls of the actual aircraft.

Read the fundamentals as described in Aerodynamics for Naval Aviators. You might learn a few things besides arguing for the sake of argument.
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Old 25th Mar 2014, 16:03
  #59 (permalink)  
 
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FWIW, on the A320, provided the speed was on (or above) the target IAS, and the VS and profile were good, I routinely closed the throttle levers between 50 ft and 30 ft. (IIRC, it's done at 50 ft for landing-performance certification.)

On the B707, I wouldn't dream of closing the thrust levers before the flare was nearly completed, unless the speed was high...
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Old 25th Mar 2014, 16:19
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Post #40 got it right.
Finger is out and not in cheek.
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