747 with 5 contrails ???

I would like to say that the outflow theory is just that, a theory. There can easily be another explanation.

I see……, thanks Whiskey Delta,
I guess i got finally a convincing answer !!
Is there anything else on large planes that make a contrail? I saw once a picture showing that wings make contrails, it’s amazing, could it be?

I think WD’s outflow theory has it.

unless skycruiser, as a 747 driver can say something to the contrary

These are the pressurization relief valves on the 747. As you can tell they are not small either.

Toilet outflows , Pressurization outflow , …..
these are small valves.

Pressuization outflows can be quite large on large jets.

I know there isn’t any scale on this picture but it’s of the 747 outflow valve.

Here’s a picture I took of a MD-80 where you can see it’s outflow valve full open on the ground. That diameter is roughly 12″.

Could it be a bleed of hot air from the Aircon packs?

Yes, which would come out of……..the outflow valve!!!

Could it be a bleed of hot air from the Aircon packs?

Toilet outflows , Pressurization outflow , …..
these are small valves , can such a small valve (or whatevere it is) make such a contrail at high altitudes? Does every hot air exit make a contrail?
I mean it’s relatively a quite big contrail, of course not compared to the engines.

There’s a heated vent associated with the system.

Hmm.. then my initial idea of the toilet outflow. Perhaps someone had just flushed whe this pic was taken

Usually *it* doesn’t go outside. It’s a closed cycle.

Toilet outflows are about as wide as your thumbs thickness so I doubt it would be possible for it to create a contrail as large as that.

Perhaps someone had just flushed whe this pic was taken

could be, but does it make such a contrail?

Hmm.. then my initial idea of the toilet outflow. Perhaps someone had just flushed whe this pic was taken

well well well….. it’s getting confusing here, if it’s not the Pressurization outflow valve cause a 747 has actually two valves ( like skycruiser said), then what is it then ?? :confused:

Tell us 😮 😮 Anna 😀

The APU can not be used above 20,000 on the 747.

Also, we have two Pressurization outflow valves on the 747, so maybe it’s something else.

Sorry for going off subject, but is smoking allowed on Cubana flights?:D

As long as they ain’t Marlboro ! :p

Sorry for going off subject, but is smoking allowed on Cubana flights?:D

That was Whiskey Delta’s answer

yes, sorry for that.

thanks guys !!

It was indeed, I thought I made it clear anough when I re-posted it, but guess not. 🙂