PDWE contrail?

Just snapped these pics a few days ago(5/25/2010 6:46EST), wondering if they are the infamous donuts on a rope from a PDWE engine.

A "full res" version of photo, taken on cell cam.

Yes. Those are "donuts on a rope".

No. They are not produced by PDWE engines. They are caused by interactions of contrails with wingtip vortices.

Maybe this will help:

Experiments have been performed to study the co-rotating wing-tip vortex pair produced by a pair of rectangular wings in a split-wing configuration. Detailed measurements made in cross-sections upstream and downstream of merger reveal, for the first time, the complex turbulence structure of this flow. The vortices spiral around each other and merge some 20 chordlengths downstream of the wings. As merger is approached the vortices lose their axisymmetry – their cores develop lopsided tangential velocity fields and the mean vorticity field is convected into filaments. The cores also become part of a single turbulence structure dominated by a braid of high turbulence levels that links them together. The braid, which quite closely resembles the structure formed between adjacent spanwise eddies of transitional mixing layers, grows in intensity with downstream distance and extends into the vortex cores. Unlike a single tip vortex, the unmerged cores appear turbulent.

The merging of the vortices wraps the cores and the flow structure that surrounds them into a large turbulent region with an intricate double spiral structure. This structure then relaxes to a closely axisymmetric state. The merged core appears stable and develops a structure similar to the laminar core of a vortex shed from a single wing. However, the turbulent region formed around the vortex core during the merger process is much larger and more axisymmetric than that found around a single wing-tip vortex.

journals.cambridge.org...

Or then again...maybe not.



[edit on 5/29/2010 by Phage]

Lol, maby not is right. I get the gist though. It seems like a interaction like that would create alot of noise on the plane.

Thanks for the informative reply

I grew up in the sixties and seventies and I remember seeing contrails in the sky back then.
I saw the same miles and miles long, lingering contrails that we have now
and even back then the contrails turned into a dirty haze in the sky.

Oh, wait a minute.
No I didn't. I don't remember anything like that from when I was a kid.
I never saw contrails that lingered for miles and miles when I was a kid.

I lived in a major city and remember watching airplanes in the sky when I was a kid.
In fact,
My grade school was right next to an international airport,
so I was very aware of airplanes in the skys when I was a child.

I remember watching airplanes fly over my city all the time.
I remember asking about what that white stuff was that came out of the airplanes
and then disappeared a short ways behind it.

I don't ever recall seeing contrails that lingered in the sky for miles and miles and eventually turned into a dirty haze
when I was young.

I especially dont recall donut shaped contrails on a contrail string.
(I like donuts so I would have remembered them.)

I do remember clear blue skys and trying to imagine what kind of animals the big white puffy clouds looked like.

I'm not saying that the kreepy lingering contrails in the back and forth criss crossing patterns in the sky along with the filthy looking haze they turn into are anything to worry about though. No worries.

Originally posted by illusions
Oh, wait a minute.
No I didn't. I don't remember anything like that from when I was a kid.
I never saw contrails that lingered for miles and miles when I was a kid.

Well air travel has increased exponentially over the last few decades, menaing there are thousands more planes in the sky, spewing out more moisture to stimulate saturation in the upper atmosphere.

Basic meteorology

reply to post by illusions

This is not a "chemtrail" thread. There are plenty of those if you want to talk about that.

This is a thread about exotic aircraft propulsion.