BA 747-400 APPROACH AT LHR
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Ford Airlane - Sorry for the third post but I can't edit from here.
On a 747-400 takeoff EPNL is about 99.8 dB @ 875,000 on approach flap 30 it is 103.8 at 652,00 and 102.1 flap 25. 747-200s at 630,00 are 105.9. Concorde on takeoff is about 120 dB if that helps.
On a 747-400 takeoff EPNL is about 99.8 dB @ 875,000 on approach flap 30 it is 103.8 at 652,00 and 102.1 flap 25. 747-200s at 630,00 are 105.9. Concorde on takeoff is about 120 dB if that helps.
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Michael B,
I'm not sure how these will format, but if you take the data into an excel page you should be able to compare the certified levels for these aircraft, I'm sorry but I dont have the DC-10 data.
Airplane/Engine/
Weight lbs/ WeightKgs/Flap/Takeoff/Sideline/Approach EPNdB
MD-11F/CF6-80C2D1F
Takeoff 630,500/285,990/10/94.7/96.2/---
Landing 481,500/218,405/50/---/---/104.5
B747-200&300/RB211-524D4/
Takeoff 833,000/377,842/10/104.1/99.7/---
Landing 630,000/285,762/30/---/---/104.9
B747-400/CF6-80C2B5F/
Takeoff 870,000/394,625/10/97.4/100.3/---
Landing 652,000/295,742/30/---/---/103.7
B727-100 JT8D-9A (Hushkitted)
Takeoff 169,500/76,883/5/94.0/97.3/---
Landing 142,500/64,637/30/---/---/98.8
747FOCAL, our rules are easy, we will listen to any presentation from a company, but not an individual, which class do you fall into?
Mutt.
[Edited for typos]
[ 13 January 2002: Message edited by: mutt ]</p>
I'm not sure how these will format, but if you take the data into an excel page you should be able to compare the certified levels for these aircraft, I'm sorry but I dont have the DC-10 data.
Airplane/Engine/
Weight lbs/ WeightKgs/Flap/Takeoff/Sideline/Approach EPNdB
MD-11F/CF6-80C2D1F
Takeoff 630,500/285,990/10/94.7/96.2/---
Landing 481,500/218,405/50/---/---/104.5
B747-200&300/RB211-524D4/
Takeoff 833,000/377,842/10/104.1/99.7/---
Landing 630,000/285,762/30/---/---/104.9
B747-400/CF6-80C2B5F/
Takeoff 870,000/394,625/10/97.4/100.3/---
Landing 652,000/295,742/30/---/---/103.7
B727-100 JT8D-9A (Hushkitted)
Takeoff 169,500/76,883/5/94.0/97.3/---
Landing 142,500/64,637/30/---/---/98.8
747FOCAL, our rules are easy, we will listen to any presentation from a company, but not an individual, which class do you fall into?
Mutt.
[Edited for typos]
[ 13 January 2002: Message edited by: mutt ]</p>
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Mutt-Well, I work for a big company that is fast making itself smaller and I have my own. You would not be getting the rantings of a private citizen. I am sure once my credentials are looked over you will have no doubts as to my background and abilities.
Michael B - I am at home and cannot give you exact levels. Mutt's look correct. Were you asking about a 747-200 or a -400? I can guarantee you that an old JT9D-7 will leave a lasting impression on what you think is noisey.
But, to answer your question.... The Large Antenov(spelling) family is probably louder. Though being Russian they are exempt from noise requirements. I think the EU is thinking that one over again though.
The big daddy of noise and is also exempt but path restricted ...... Drum roll........
CONCORDE @ 120 dB and I have seen LHR monitor data with it at 125 dB on takeoff. Good that it doesn't stick around long.
Michael B - I am at home and cannot give you exact levels. Mutt's look correct. Were you asking about a 747-200 or a -400? I can guarantee you that an old JT9D-7 will leave a lasting impression on what you think is noisey.
But, to answer your question.... The Large Antenov(spelling) family is probably louder. Though being Russian they are exempt from noise requirements. I think the EU is thinking that one over again though.
The big daddy of noise and is also exempt but path restricted ...... Drum roll........
CONCORDE @ 120 dB and I have seen LHR monitor data with it at 125 dB on takeoff. Good that it doesn't stick around long.
Ford Airlane, use of full reverse thrust will not reduce your landing distance if autobraking is used - and I'm sure that most pilots will use autobraking as per their company SOPs as opposed to manual braking, esp at a hot/high place like Jo'berg. This is beacause autobrakes set a measured decceleration rate as sensed by the IRSs. Application of reverse thrust above idle will result in the IRSs releasing the brakes a bit to maintain the set rate. You will only decrease the landing roll if you manually brake, and this will probably result in increased brake wear on carbon brakes for the reasons stated previously in this thread.
For those who are interested by the boring details, these rates are 2 feet per second/per second for autobrake 1, 3 fps/s for autobrake 2, 4 fps/s for 3 et seq.
For those who are interested by the boring details, these rates are 2 feet per second/per second for autobrake 1, 3 fps/s for autobrake 2, 4 fps/s for 3 et seq.
Just another number
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747FOCAL
We (BA) always use Flap 25 at LHR except in Cat 3 conditions when we use Flap 30 as the lower pitch attitude gives better visibility.
We take noise issues very seriously, and train our crews in noise reduction techniques. However, if you have any suggestions for improvement, we are always willing to learn.
Airclues
We (BA) always use Flap 25 at LHR except in Cat 3 conditions when we use Flap 30 as the lower pitch attitude gives better visibility.
We take noise issues very seriously, and train our crews in noise reduction techniques. However, if you have any suggestions for improvement, we are always willing to learn.
Airclues
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Dan,
You are, of course, correct about the measured deceleration rates with autobrakes and contribution of reverse thrust having no effect on actual deceleration rate with autobrakes. I mentioned reverse thrust in the case where autobrakes, for whatever reason, are not used.
Three things are required for the autobrakes to function if they are armed:
1. Ground mode sensed; &
2. Thrust levers at idle on ALL engines; &
3. Wheel spinup has occurred.
I highlighted the "ALL" in nr 2 as in the case of Qantas 1 at BKK the autobrakes disarmed very early in the landing roll as , I believe, the nr 1 thrust lever was advanced slightly out of idle, disarming the autobrakes. Full reverse thrust, in this case, would have reduced the distance used.
747FOCAL, 250 kilos sounds a touch light, I assume you mean 250,000!! 250t is probably a little heavier than most Qantas aircraft land at LHR. I would think avg landing weight would be closer to 240. Don't quote me on that.
<img src="smile.gif" border="0">
You are, of course, correct about the measured deceleration rates with autobrakes and contribution of reverse thrust having no effect on actual deceleration rate with autobrakes. I mentioned reverse thrust in the case where autobrakes, for whatever reason, are not used.
Three things are required for the autobrakes to function if they are armed:
1. Ground mode sensed; &
2. Thrust levers at idle on ALL engines; &
3. Wheel spinup has occurred.
I highlighted the "ALL" in nr 2 as in the case of Qantas 1 at BKK the autobrakes disarmed very early in the landing roll as , I believe, the nr 1 thrust lever was advanced slightly out of idle, disarming the autobrakes. Full reverse thrust, in this case, would have reduced the distance used.
747FOCAL, 250 kilos sounds a touch light, I assume you mean 250,000!! 250t is probably a little heavier than most Qantas aircraft land at LHR. I would think avg landing weight would be closer to 240. Don't quote me on that.
<img src="smile.gif" border="0">
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I appreciate the info and Captain I will be approaching airlines in the future in the hopes of "prying my wares" and teach techniques that can when appplied correctly lower operational noise levels.
If 240 tons is the average landing weight for Qantas at LHR from home then I got work to do.
If 240 tons is the average landing weight for Qantas at LHR from home then I got work to do.
Just how much sirframe noise is generated(as opposed to engine noise) in the following configurations.
1, Clean at 250 kts and 3000' agl and
2, Full flap and gear down at Vref
I have also noticed, that the GE powered 747's are much quieter as they taxi past than the Rolls powered ones. It seems that the exhaust ports on the pylons from the aux numatic hydraulic pumps emit more noise than the engine itself.
1, Clean at 250 kts and 3000' agl and
2, Full flap and gear down at Vref
I have also noticed, that the GE powered 747's are much quieter as they taxi past than the Rolls powered ones. It seems that the exhaust ports on the pylons from the aux numatic hydraulic pumps emit more noise than the engine itself.
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Clean the airframe noise is buried in the noise of the engines and would not show up in the measured noise levels. A 747 all engines off, full flap and gear down will register about 101 dB. Give or take a few tenths. It's them fowler flaps that cause the majority of it.
