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Topic: 747-400 Climb Out Profile Quiet Climb And No Restr
Username: Julesmusician
Posted 2006-01-22 13:35:15 and read 14784 times.

Can someone tell me the different climb rates that a fully loaded 747-400 would do on a climb out where there are a lot of noise restrictions such as a big city and a climb out where there are no noise restrictions such as a pacific island going out over the sea?

What i am looking for is the different vert speed profiles in feet per minute that the autopilot/flight management computer would set for each part of the climb for the noise restricted and the no restriction climb?

Thanks,

J

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No Restr
Username: PhilSquares
Posted 2006-01-22 14:34:32 and read 14789 times.

The FMS doesn't set V/S. The climb profiles are really a function of obstacles and close in or distant noise restrictions.

At SQ, we always use 20 flaps. Our normal profile is at 1000'AGL we start the flap retraction and climb power is selected when the flaps are at 5. For noise restricted airports, we clean up at 3000'AGL during the initial climb, climb thrust is selected passing 1500'AGL.

Some airports mandate full power takeoffs, while others are silent. Normally, you will use the least amount of thrust. Our SOP is a max of TO-1 52C derate.

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No Restr
Username: Mr Spaceman
Posted 2006-01-22 15:43:53 and read 14767 times.

Hi guys.

Quoting PhilSquares (Reply 1):
Our SOP is a max of TO-1 52C derate.

Hi PhilSquares, I'm having trouble figuring out the Standard Operating Procedure that you listed above. What does that mean?

I'm used to take off thrust settings being explained as a percentage of the N1 stage of the engines. Such as a derated thrust setting of 74% of N1 is needed for take off with the current conditions ... as an example.

Is your SOP info above explaining that a derated take off is set by referring to temperatures. Does 52C derate stand for a 52 Celsius change in EGT?


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Thanks,

Chris  Smile

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No Restr
Username: PhilSquares
Posted 2006-01-22 16:07:07 and read 14758 times.

No, on the PW TO power is set by EPR. So, TO-1 52C is 1.34 EPR. While full TO would be about 1.53 EPR.

The 52C is referring to the "assumed temperature" method of derate. The takeoff numbers are roughly what you would have for a 52C takeoff using TO-1.

Hope that helps.

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No Restr
Username: Jetflyer
Posted 2006-01-22 17:02:22 and read 14737 times.

What's the actual rate of climb??

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No Restr
Username: Mr Spaceman
Posted 2006-01-22 17:08:48 and read 14735 times.

Hi PhilSquares.

OK, I understand now that on the Pratt & Whitney engines, T/O power is set by EPR (Engine Pressure Ratio), not a % of N1. This makes sense to me because I guess you could require many different N1% numbers to achieve the same EPR setting .... due to different outside air temperatures. (OAT)

So, when using your SOP's derated TO setting of TO-1, the EPR gauges will be indicating 1.34 EPR at Vr speed.

I guess it's safe to say the default temp of 52C for the "assumed temperature" method of derating TO power is referring to the temp of the engine's intake air after being compressed ....... and not the ambient outside air temp. Big grin

Quoting PhilSquares (Reply 3):
Hope that helps.

Yes Sir, it does. Thank You.


Chris  Smile

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No R
Username: Julesmusician
Posted 2006-01-22 20:02:26 and read 14694 times.

Quoting PhilSquares (Reply 1):
The FMS doesn't set V/S. The climb profiles are really a function of obstacles and close in or distant noise restrictions.

Ok assuming you are climbing out from an island over the sea with no obstacles and the game plan is left to you to get to your cruising level - how would you set it up with the autopilot doing the work and how would you choose which of the below height vs distance profiles you would use?

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No Restr
Username: PhilSquares
Posted 2006-01-22 23:07:36 and read 14649 times.

Quoting Jetflyer (Reply 4):
What's the actual rate of climb??

Depends on your Gross Weight!

Quoting Mr Spaceman (Reply 5):
So, when using your SOP's derated TO setting of TO-1, the EPR gauges will be indicating 1.34 EPR at Vr speed.

No, takeoff thrust must be set by 80 KIAS. So, it will be long before VR

Quoting Mr Spaceman (Reply 5):
I guess it's safe to say the default temp of 52C for the "assumed temperature" method of derating TO power is referring to the temp of the engine's intake air after being compressed ....... and not the ambient outside air temp.

Actually, it is referring to the OAT.

Quoting Julesmusician (Reply 6):
Ok assuming you are climbing out from an island over the sea with no obstacles and the game plan is left to you to get to your cruising level - how would you set it up with the autopilot doing the work and how would you choose which of the below height vs distance profiles you would use?

First of all, the autopilot wouldn't do anything. You would most likely hand fly the aircraft. However, SOP takes care of everything. You'd use the first method I described. Begin flap retraction at 1000'AGL and assuming you didn't have any speed restriction (250 below 10,000') you would accelerate to the FMS derived climb speed. That speed is gross weight dependent. The heavier you are, the faster it is. You maintain that IAS until you intercept your climb MN. (,85 roughly) and then climb at your climb MN until your cruise alt.

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No Restr
Username: Rendezvous
Posted 2006-01-23 11:11:34 and read 14537 times.

The climb speed is a function of the cost index which is set on the FMC. I'm not sure what each airline uses, but a high cost index will result in a high forward speed, whereas a lower cost index will bring the plane closer to the max rate of climb speed.

The greater the forward speed, the further you get into your trip quicker. If you climb at slow speeds then it takes longer to "get moving".

Other factors of course play a part, as mentioned above, including altitude requirements (for example 8000' by 20nm), also noise abatement and winds aloft.

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No R
Username: Jetflyer
Posted 2006-01-23 17:07:57 and read 14478 times.

"Noise restrictions" on the 747 sound like a bit of a joke. When I lived 8 miles west of Heathrow, the 747s would ALWAYS struggle out of runway 27L/R whichever on departure, around I'd say 2500-3000ft high maybe, and they made a bloody RACKET. Far, far louder than the 737-200 or MD-80s with low bypass engines. The windows of my house would rattle and so would picture frames etc... I'm sure the best "noise abatement" is the fastest climb you can possibly manage...sure as hell blasting over my house at about 0.0001fpom climb rate keeps you up all night.

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No Restr
Username: Julesmusician
Posted 2006-01-23 19:47:02 and read 14455 times.

Quoting PhilSquares (Reply 7):
However, SOP takes care of everything

Now SOP's are company specific I assume? Not Boeing produced, but a company process rather than the manufacturer's guide?

Quoting PhilSquares (Reply 7):
you would accelerate to the FMS derived climb speed

FMS climb speed being the forward speed & the vertical speed or just the forward speed? What pilot "options" are there - can you ask for specific climb profiles such as "as quiet as possible" or "max climb to cruising level please" and similar?

Quoting Rendezvous (Reply 8):
The climb speed is a function of the cost index which is set on the FMC

So for maximum fuel efficient climb out what kind of profile are we looking at? A fast forward slow vertical or a fast vertical and slow forward? What would the FMS prefer?

All very interesting answers. As always with me there are likely to be more questions  Smile

J

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No Restr
Username: PhilSquares
Posted 2006-01-24 02:18:24 and read 14392 times.

Quoting Julesmusician (Reply 10):
Now SOP's are company specific I assume? Not Boeing produced, but a company process rather than the manufacturer's guide?

Yes, SOPs are company specific. They do have to be "approved" by the aircraft mfgr to make sure there is no conflict with the mfgr's recommendations. But, the bottom line is all the checklists and SOPs are tailored for each operator.

Quoting Julesmusician (Reply 10):
FMS climb speed being the forward speed & the vertical speed or just the forward speed? What pilot "options" are there - can you ask for specific climb profiles such as "as quiet as possible" or "max climb to cruising level please" and similar?

FMS climb speed is KIAS/MN. There are a host of options available, such as max rate/max angle, but normally at airports, especially noise sensitive airports, the climb procedure is spelled out in no uncertain terms. So for the person who was complaining about the 747s out of LHR, it's BAA not the airlines he should be complaining to.

Quoting Julesmusician (Reply 10):
So for maximum fuel efficient climb out what kind of profile are we looking at? A fast forward slow vertical or a fast vertical and slow forward? What would the FMS prefer?

I can only speak about the 744, but the econ climb, with no speed restrictions (250 below 10000') will give the most fuel efficient climb. The KIAS is driven by gross weight, the heavier you are the faster KIAS you climb at. For the most part as you get above 330 tonnes, you'll climb at 340KIAS till intercepting .85M and then climb at that. That will normally result in a climb of 2500 FPM until the high 20s then it gradually decreases as you maintain your KIAS. Once you intercept the MN then you get an increase in climb rate. If you're really heavy then you will climb at KIAS since your initial cruise altitude will be in the very low 30s.

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No Restr
Username: Stoicescu
Posted 2006-01-24 04:23:01 and read 14375 times.

What is the Vx and Vy for the 744 ?

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No Restr
Username: PhilSquares
Posted 2006-01-24 07:13:23 and read 14350 times.

Vx and Vy are both weight dependent. So they will vary with gross weight. IIRC Vx is Vref + 80, but the easiest way is to look in the FMS.

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No Restr
Username: Julesmusician
Posted 2006-01-24 21:19:21 and read 14303 times.

Quoting PhilSquares (Reply 11):
SOPs are company specific. They do have to be "approved" by the aircraft mfgr to make sure there is no conflict with the mfgr's recommendations

But why rewrite the rules? Companies will be flying the aircraft in the same weight margins as other companies so surely SOP's for the 747-400 will be the same for all airlines (depending on the engine fitted) - if you have a taxi firm you wouldn't rewrite the car manuals for each individual car so why do companies have SOP's for each aircraft when they already come with procedures for all the different combinations of weight etc?

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No Restr
Username: David L
Posted 2006-01-24 22:07:50 and read 14288 times.

Quoting Julesmusician (Reply 14):
if you have a taxi firm you wouldn't rewrite the car manuals for each individual car

But what if the car manufacturer says "never exceed 8000 rpm", taxi company A tells its drivers never to exceed 7500 rpm to reduce wear on the engine and taxi company B tells its drivers never to exceed 7000 rpm for the same reasons? Both companies can decide on their own limit but couldn't set a limit of 9000 rpm as that would conflict with the manufacturer's recommendations.

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No Restr
Username: PhilSquares
Posted 2006-01-25 01:14:00 and read 14259 times.

Quoting Julesmusician (Reply 14):
But why rewrite the rules? Companies will be flying the aircraft in the same weight margins as other companies so surely SOP's for the 747-400 will be the same for all airlines (depending on the engine fitted) - if you have a taxi firm you wouldn't rewrite the car manuals for each individual car so why do companies have SOP's for each aircraft when they already come with procedures for all the different combinations of weight etc?

It's not quite that simple. Some airlines fly various types of aircraft, so they want to ensure there is standardization accross the fleets. Thus the checklist and SOP will be as standard as possible. Other airlines have a more conservative philosophy, thus they will arrange their SOP and checklist to reflect that philosophy.


From Boeing's perspective, for example, as long as the operator doesn't exceed any limits or recommendations it makes no difference to them.

Topic: RE: 747-400 Climb Out Profile Quiet Climb And No Restr
Username: AM
Posted 2006-01-25 17:52:51 and read 14205 times.

Quoting PhilSquares (Reply 1):
At SQ, we always use 20 flaps. Our normal profile is at 1000'AGL we start the flap retraction and climb power is selected when the flaps are at 5. For noise restricted airports, we clean up at 3000'AGL during the initial climb, climb thrust is selected passing 1500'AGL.

PhilSquares,

I didn't know that acceleration altitude could be lower than thrust reduction altitude. Interesting.

So how would you manage speeds and thrust settings during the normal profile climb you described? What I knew about the B744 for an accel. alt. higher than thrust reduction alt. is, in general terms, like this:

- Both altitudes I mentioned are selected in the FMS prior to departure, as well as the particular climb derate.
- At thrust reduction alt., with VNAV armed, climb power is automatically selected.
- At accel. alt., again with VNAV as the active mode, pitch is adjusted to accelerate from V2+10 (or V2+15?) to the FMS climb speed, or any speed restriction (like 250 KIAS below 10000').
- After accel. alt., flaps are retracted according to flap retraction schedule, which is a function of each setting's maneuvering speed.

Please correct me if I'm wrong. That's kind of the general idea I have. How would this work and how would you interact with the FMS when accel. alt. is lower than thrust reduction alt., and the latter is a function of flaps 5?

Thanks a lot in advance!


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