Tin67
Topic Author
Posts: 268
Joined: Mon May 10, 2004 3:49 am

Question About Overflying 747 Trails

Mon Nov 15, 2004 5:18 am

I was at this afternoon and took this shot of a 747 overflying. I was intrigued to the 5 trails.

Any idea what the centre trail from the fuselage is?

http://www.airliners.net/addphotos/big/ready/KA6S1754_LHR_AF_OVER.jpg



Regards
Martin

[Edited 2004-11-14 21:19:42]
 
User avatar
TupolevTu154
Posts: 1921
Joined: Fri Aug 27, 2004 6:00 pm

RE: Question About Overflying 747 Trails

Mon Nov 15, 2004 5:22 am

I heard once that the aircraft occasionally dumps some water, there is a pic of a JAL 744 with a fifth trail, AH here it is!


View Large View Medium
Click here for bigger photo!

Photo © Bailey - AirTeamImages



Or it could be the APU?

Tom
 
Airplanepics
Posts: 2591
Joined: Fri Jun 27, 2003 4:12 am

RE: Question About Overflying 747 Trails

Mon Nov 15, 2004 5:24 am

Most probably the APU.


Simon
Simon - London-Aviation.com
 
Tin67
Topic Author
Posts: 268
Joined: Mon May 10, 2004 3:49 am

RE: Question About Overflying 747 Trails

Mon Nov 15, 2004 5:29 am

I though the APU when I saw it, but it seems to be coming from under the fuselage rather that the APU exhaust.

I see the text on Bailey's photo posted above by Tom that suggests the sink drains from the toilets. Interesting.

Cheers
Martin
 
javibi
Posts: 1295
Joined: Sat Oct 02, 2004 5:55 pm

RE: Question About Overflying 747 Trails

Mon Nov 15, 2004 5:56 am

As Bailey states, the fifth contrail is produced by water from the toilets and galleys sinks, which is thrown directly overboard via several drain masts.

The APU won't be running at cruise level, unless you have a serious problem.

Regards

j
 
Erwin972
Posts: 470
Joined: Sun May 30, 2004 2:21 am

RE: Question About Overflying 747 Trails

Mon Nov 15, 2004 6:41 am


To add to that: the drains under the belly are also heated to prevent icing. APU isn't running at cruise.


View Large View Medium
Click here for bigger photo!

Photo © Erwin




Kind regards,
Erwin
My gear: Nikon, Sony, Red, Sachtler etc.

Who is online

Users browsing this forum: No registered users and 1 guest

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos