LMP737
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New Tail Cones For AA MD-80's

Tue Jul 11, 2006 3:06 am

Periodically the topic of AA's low and high drag tailcones comes up on the forums. Well folks the older high drag tailcones will soon be a thing of the past.

When Jet A was cheap and AA was making money hand over fist replacing the older style cones was never a priority. However given the current price of Jet A and market conditions AA is looking to save money anywhere it can. One area obviously is aerodynamic improvements to it's fleet. We have already seen that with winglets on it's 757's and 737's. AA looked into buying MD-80 tailcones from Boeing. Unfortunately the price tag was $278,000. On the surplus market there were only two available. So AA decided to make their own low drag MD-80 tailcones at it's TUL facility.

Starting June AA started producing approximately eight a month in order to replace the 105 high drag tailcones in it's fleet. The cost to make them will be around $30,000. The old style tailcones burn up to $28,000 a year more in fuel. In little over a year AA will recoup the costs of production. Total fuel savings will be around $3 million. They will be installed when the aircraft makes a visit to TUL for light and heavy checks.
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2H4
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RE: New Tail Cones For AA MD-80's

Tue Jul 11, 2006 3:28 am



Any word on the percentage of drag reduction offered by the new tailcones?




2H4


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LMP737
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RE: New Tail Cones For AA MD-80's

Tue Jul 11, 2006 3:51 am

Quoting 2H4 (Reply 1):
Any word on the percentage of drag reduction offered by the new tailcones?

From what I have heard it offers about a 1% reduction in fuel consumption.
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highflyer9790
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RE: New Tail Cones For AA MD-80's

Tue Jul 11, 2006 4:29 am

Any pics of the high drag vs. low drag tail cones?
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Starlionblue
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RE: New Tail Cones For AA MD-80's

Tue Jul 11, 2006 4:45 am

Quoting HighFlyer9790 (Reply 3):
Any pics of the high drag vs. low drag tail cones?

It's not really fair to call the pointy type "high drag". It's not like a drift anchor  Wink But yes, the flathead screwdriver AKA beavertail produces less drag.

Cone:

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Photo © Damon Marcus Lewis



Screwdriver:

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Photo © Stefan Sjögren - Stockholm Arlanda Photography

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LTU932
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RE: New Tail Cones For AA MD-80's

Tue Jul 11, 2006 5:00 am

They can replace the tailcone, just like that? How is that possible for a technical point of view? How do you proceed to replace the cone tail with the screwdriver tail?

This is another part of Douglas design that has truely surprised me. Too bad they're gone now.

BTW, just for the sake of a discussion, could it be possible to outfit for example NW's DC-9s with the screwdriver? Or is anything that is a DC-9-10 to -50 not designed for a change of tailcone? I know financially, NW might not be able to afford it, but hypothetically, is a tail swap like what AA will do on the MD-80, also possible on the classic DC-9s?
 
LMP737
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RE: New Tail Cones For AA MD-80's

Tue Jul 11, 2006 6:07 am

Quoting LTU932 (Reply 5):
They can replace the tailcone, just like that? How is that possible for a technical point of view? How do you proceed to replace the cone tail with the screwdriver tail?

The tailcone on the MD-80 was designed to be jetisoned in the event of an emergency. It's quite easy to replace them. All you have to do is release the latches and off it comes. In the picture below you see the tail on an AA MD-80. The part that's painted grey, composite material, is the part that's being replaced.


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Photo © Dan Brownlee



Quoting LTU932 (Reply 5):
BTW, just for the sake of a discussion, could it be possible to outfit for example NW's DC-9s with the screwdriver? Or is anything that is a DC-9-10 to -50 not designed for a change of tailcone?

Since an MD-80 is nothing more than a stretched DC-9 I believe you could. I know that you can use the same radome on a DC-9 as on a MD-80.
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LTU932
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RE: New Tail Cones For AA MD-80's

Tue Jul 11, 2006 6:10 am

Quoting LMP737 (Reply 6):
All you have to do is release the latches and off it comes.

OK, thanks.

Quoting LMP737 (Reply 6):
The tailcone on the MD-80 was designed to be jetisoned in the event of an emergency.

In which emergency situations do they do this? And what's the purpose of having to jettison the tailcone?
 
LMP737
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RE: New Tail Cones For AA MD-80's

Tue Jul 11, 2006 6:15 am

Quoting LTU932 (Reply 7):
In which emergency situations do they do this? And what's the purpose of having to jettison the tailcone?

Anytime you have to get off that aircraft in a hurry. By having the tailcone jettionsable is just another added measure of safety. More ways off the aircraft increases chances of survival.
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LTU932
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RE: New Tail Cones For AA MD-80's

Tue Jul 11, 2006 6:18 am

Quoting LMP737 (Reply 8):
Anytime you have to get off that aircraft in a hurry. By having the tailcone jettionsable is just another added measure of safety. More ways off the aircraft increases chances of survival.

OK, I understand that now. Thanks.
 
MD-90
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RE: New Tail Cones For AA MD-80's

Tue Jul 11, 2006 7:26 am

This DC-9-14 shows the jettisoned tail cone after an emergency evacuation.


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Photo © Juan Carlos Guerra - APM

 
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Starlionblue
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RE: New Tail Cones For AA MD-80's

Tue Jul 11, 2006 8:47 am

Quoting LTU932 (Reply 7):
Quoting LMP737 (Reply 6):
The tailcone on the MD-80 was designed to be jetisoned in the event of an emergency.

In which emergency situations do they do this? And what's the purpose of having to jettison the tailcone?

The aft slide is deployed through the hole left by the jettisoned tailcone. Faster than lowering the airstairs. Also, if the plane is lying on the ground the airstairs won't work.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
L-188
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RE: New Tail Cones For AA MD-80's

Tue Jul 11, 2006 10:53 am

Quoting Starlionblue (Reply 11):
Quoting LTU932 (Reply 7):
Quoting LMP737 (Reply 6):
The tailcone on the MD-80 was designed to be jetisoned in the event of an emergency.

In which emergency situations do they do this? And what's the purpose of having to jettison the tailcone?

The aft slide is deployed through the hole left by the jettisoned tailcone. Faster than lowering the airstairs. Also, if the plane is lying on the ground the airstairs won't work.

Anybody remember the movie "Cliffhanger"

That was one of the stunts. The tailcone is popped off a MD-80 and the bank robbers then rappel in to a trailing westwind..

All at 400 kts and 35,000 feet of course.
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Dalmd88
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RE: New Tail Cones For AA MD-80's

Tue Jul 11, 2006 6:07 pm

The "Cliffhanger" stunt looked cool, but it is impossible. The tail cone will not fall off while in flight. You can release it, but aerodynamic drag will keep it sucked up to the end of the plane.
 
avconsultant
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RE: New Tail Cones For AA MD-80's

Wed Jul 12, 2006 12:14 am

As a young kid in the 70's, I thought I remember hearing about a DC-9 tailcone separating in flight.
 
highflyer9790
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RE: New Tail Cones For AA MD-80's

Fri Jul 14, 2006 10:45 am

If the "flathead screwdriver" tail "cap" is high-drag, is it just me or does it look similar to the 777's tail cap. does this infer that the 777 has a high drag tail cap? (i didn't use "tail cone" because cone refers to the new low drag, does it not?)

so called "high drag" MD-80 tail:

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Photo © Stefan Sjögren - Stockholm Arlanda Photography



777 tail:

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Photo © Danny Fritsche - Airplanespotters

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Starlionblue
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RE: New Tail Cones For AA MD-80's

Fri Jul 14, 2006 10:58 am

Quoting HighFlyer9790 (Reply 15):
If the "flathead screwdriver" tail "cap" is high-drag, is it just me or does it look similar to the 777's tail cap. does this infer that the 777 has a high drag tail cap? (i didn't use "tail cone" because cone refers to the new low drag, does it not?)

You got it turned around. The screwdriver is the lower drag, improved variant. The pointy one is the older variant.
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highflyer9790
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RE: New Tail Cones For AA MD-80's

Fri Jul 14, 2006 11:47 am

Quoting Starlionblue (Reply 16):
Quoting HighFlyer9790 (Reply 15):
If the "flathead screwdriver" tail "cap" is high-drag, is it just me or does it look similar to the 777's tail cap. does this infer that the 777 has a high drag tail cap? (i didn't use "tail cone" because cone refers to the new low drag, does it not?)

You got it turned around. The screwdriver is the lower drag, improved variant. The pointy one is the older variant.

oops, guess i did.  banghead  it makes much more sense to me now! thanks Starlionblue!
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