Rocket-spotting by midnight sun, Russia, June 17

Here's a midnight-sun rocket-watching party in Russia, who had live radio comments on the navsat launch from Plesetsk, they knew in advance it was scheduled, and picked an awesome site over a lake. No need to understand the Russian, their excited voices say plenty.
www.youtube.com...

a reply to: JimOberg

Does this mean that the rocket will explode in a spectacular manner...?

a reply to: JimOberg

Very cool find and a gorgeously beautiful display. If I'd have been in the area and realised how cool it would look I'd have taken a folding stool, something to smoke and a couple of six-packs too.

I know less than nothing about rockets. At first you see a regular smoke/contrail then it morphs into a huge envelope or bubble. Is that an altitude/speed related thing? Thanks for posting.

originally posted by: LightSpeedDriver
a reply to: JimOberg

Very cool find and a gorgeously beautiful display. If I'd have been in the area and realised how cool it would look I'd have taken a folding stool, something to smoke and a couple of six-packs too.

I know less than nothing about rockets. At first you see a regular smoke/contrail then it morphs into a huge envelope or bubble. Is that an altitude/speed related thing? Thanks for posting.

I do some general background discussion on this earlier case, hope you find it useful...
satobs.org...

Beautiful! Love the staging at 5:52.

originally posted by: LightSpeedDriver
a reply to: JimOberg
I know less than nothing about rockets. At first you see a regular smoke/contrail then it morphs into a huge envelope or bubble. Is that an altitude/speed related thing?

It's an altitude/air pressure thing. In thick air, the exhaust pulls the air along with it, and in turn the air constrains the exhaust to a narrow column. In vacuum, the exhaust is not constrained, and expands rapidly in a wide cone as it leaves the rocket nozzle (the acceleration of the rocket makes the "walls" of the cone look curved). As the rocket ascends through the atmosphere towards space (and the air pressure decreases), we see the transition from the narrow column to the wide, curved cone.

You can see this effect in any long tracking shot of a rocket launch. Here's the Falcon Heavy launch from last February. You can start to see the spreading around 23:00, and it becomes quite prominent by 24:00.



Hope this helps.

The changing plume behavior as air density drops to zero actually provides a reliable measuring stick for the scale of the image, the 'Karman line' [about 100 km up] where aero effects essentially disappear.

A second scale determinant is provided by any short rocket burns that can be observed. Since the upper stage engines have known performance, the plume ejection velocity can be calculated, so if the burn is timed [using a video], the duration times speed of the plume provides the scale of the plume length. It needs to be corrected by the cosine of the 'angle-off', the amount of the line-of-sight not being perpendicular. You can calculate THAT by comparing the rocket's ground track with the lo9cation of the observer.

An example of that, here --
satobs.org...

Ain't 'rocket science' neat? This has been my retirement hobby the last few years.

Great footage, thanks for sharing. Russian is my frist language.

I wanna say that it's not "midnight sun" as the sun had already set below the horizon. Rather, it's called "white nights" in the northern regions of Russia.

These expanding plumes lit by the Sun against a dark sky are some of my favourite rocket launch footage.

Here's one from a few years ago:

www.youtube.com...

a reply to: wildespace


White nights it is, I stand gratefully corrected, thank you!

I'm still trying to figure out the SOURCE of the live mission coverage narration in the background, he's hearing it over the radio. I have never encountered such public broadcast of such launch details with Russian military launches. Did the narrator give ANY description of the source of that broadcast in his own comments? I couldn't detect it, my Russian is not bad, but far from perfect.

originally posted by: JimOberg
a reply to: wildespace


White nights it is, I stand gratefully corrected, thank you!

I'm still trying to figure out the SOURCE of the live mission coverage narration in the background, he's hearing it over the radio. I have never encountered such public broadcast of such launch details with Russian military launches. Did the narrator give ANY description of the source of that broadcast in his own comments? I couldn't detect it, my Russian is not bad, but far from perfect.

The video author said he just overlaid a sound track he found on the Internet. So it's not genuine broadcast for that launch, sorry.

a reply to: wildespace

Thanks, I was trying to rectify the described mission events with the visual indicators. Sounds like that was not possible.

On the topic of awesome night-time launches, here's a recent one from SpaceX Dragon launch:


www.youtube.com...

Very good tracking there by our former member ngchunter.