Logan22L
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DC-9 Take-off Flap Setting

Wed Feb 16, 2005 2:20 am

I couldn't find any related threads, so I hope you can help with answers to two questions regarding the DC-9.

1. On take-off yesterday in a DC-9-50, I noticed that the flaps were just barely deployed (hardly even looked like 5 degrees), unlike a typical take-off setting in other aircraft. We were full, and going DTW-BOS; temp was ~35 F. This seems very strange, as I have heard of some jets using very little flap deployment, but not DC-9s (the co-oincidence of being in DTW (MD-80, 1987) added a bit to my apprehension).

2. Last Friday, BOS-DTW in a DC-9-30 I sat in the exit row (seat 11F). Despite many flights, my first exit row. Anyway, as we taxied, I could clearly hear the engines in a much different way than normal. It was as if there were a conduit from the engines to the emergency exit door, and I could hear the engine with much more clarity than I have from other seats. I actually asked the purser if this was normal, and he said everything was fine, but it almost seemed as though I could hear the outside, as if the door were not sealed. Everything went fine, and I could not notice this in flight. Just during taxi and on take-off roll. Any thoughts?

These both go to show that despite any layman's concerns (such as mine), the flight crew and the airlines know what the heck is going on.

Thanks,

Logan
"The deeper you go, the higher you fly. The higher you fly, the deeper you go."
 
SlamClick
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RE: DC-9 Take-off Flap Setting

Wed Feb 16, 2005 2:59 am

Not familiar with, or at least not qualified on the -50 but I've heard that on the -30 it was not uncommon to make a slats-only, no-flap takeoff from hot and high airports, where 2nd segment climb was the performance limiter.

That does not sound like a cold day at DTW issue.

Perhaps someone with experience in that subtype can jump in.

As to the noise, it may well be that insulation and soundproofing are not as good near the emergency exits as in the rest of the cabin.
Happiness is not seeing another trite Ste. Maarten photo all week long.
 
AirWillie6475
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RE: DC-9 Take-off Flap Setting

Wed Feb 16, 2005 4:28 am

I could hear the outside, as if the door were not sealed

Even if the door wasn't sealed, initially, that wouldn't be a problem on a pressurized jet. Unless there was a big hole... If your afraid of abnormal noise in an aircraft riding the DC9-30 probably wouldn't be a good idea. Like an old car they sometimes make strange noises.
 
prebennorholm
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RE: DC-9 Take-off Flap Setting

Wed Feb 16, 2005 9:22 am

Having flown in the back of a DC-9 a hundred times, mostly on -40 and to a lesser degree the -20:

On the -40 most often very little flaps were used for take off. Only a few degrees, hardly noticeable.

On the -20 mostly some 10 or 15 degrees was used.

The exit seats are somewhat more noisy since the fuselage here contains more substantial metal structures which leaves less space for sound proofing material.

Maybe one day you should take a ride on a military C-130 Hercules transport or such without sound proofing. Then you will appreciate what sound proofing of airliner cabins does to our wellbeing.
Always keep your number of landings equal to your number of take-offs
 
SlamClick
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RE: DC-9 Take-off Flap Setting

Wed Feb 16, 2005 11:56 am

I was thinking of a ride in an early Sikorsky helicopter with the engine in front of you and the transmission overhead, with the tail rotor drive shaft extending beyond that. Now there is a noise level!
Happiness is not seeing another trite Ste. Maarten photo all week long.
 
AvionicMech
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RE: DC-9 Take-off Flap Setting

Wed Feb 16, 2005 12:25 pm

You will find that on almost every aircraft it is noisier near the exits for the pure reason that there is less insulation on the door. This is because behind the trim panel that you can see there is all the opening mechanism which doesn't like having an insulation blanket tangled in it. So for this reason there is usually a thin blanket which doesn't provide anywhere near as much heat and noise insulation as the rest of the cabin. This is one of the downsides of an exit row, you may get the legroom but it can be colder and more noisy than the rest of the aircraft.

Avionic Mech
 
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HAWK21M
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RE: DC-9 Take-off Flap Setting

Wed Feb 16, 2005 4:36 pm

2nd segment climb
What exactly is a 2nd Segment climb.[Reply#1].

The exit seats are somewhat more noisy since the fuselage here contains more substantial metal structures which leaves less space for sound proofing material
Freighters usually have the Insulation Blankets removed from the Main deck areas,to reduce Weight.Its noisy but a lot of weight saving  Smile

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Logan22L
Topic Author
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RE: DC-9 Take-off Flap Setting

Thu Feb 17, 2005 1:05 am

Thanks for the replies. I didn't mind the engine noise so much as I just wanted to be sure the door was secure.

Anyway, a few of you have indicated that DC-9s use no or very little flap on take-off. Remember the MD-80 that went down at DTW in 1987 due to zero flaps? Why does the MD-80 have a problem with this, because it is larger/heavier than a DC-9?

Logan
"The deeper you go, the higher you fly. The higher you fly, the deeper you go."
 
SlamClick
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RE: DC-9 Take-off Flap Setting

Thu Feb 17, 2005 1:31 am


Quoting HAWK21M (reply 6):
2nd segment climb
What exactly is a 2nd Segment climb.[Reply#1].


Under US regulations, for performance purposes the takeoff and climb are divided into segments. In each case they refer to a situation where an engine has failed after V1.

Intial is from liftoff through 35 feet which can be assumed to be the gear retraction height. (there is a bit more to it but that is a fair statement)

Second segment is with gear UP and flaps in the takeoff setting.

Final climb can be thought of as after flap retraction.

Each segment has its own climb performance criteria and from 2nd segment on these differ for 2, 3, and 4 engine airplanes.

There are many variables, some of them not obvious. Sometimes the runway will be the limiting factor, sometimes one of the climb segments. Hot days and high elevation airports it is quite common for 2nd segment to be the most restrictive.
Happiness is not seeing another trite Ste. Maarten photo all week long.

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