SpaceX F9 : Starlink v0.9 : May 23, 2019 - DISCUSSION

[CorvusCorax]

While Angle of attack is indeed commonly used with lifting surfaces ( aka wings, etc...) the term itself is defined for ANY surface within a fluid flow.

For a flat surface, the angle of attack is the angle betwern the surface and the direction of airflow. If its 0, the fluid flows parallel to the surface, if its 90 degrees, the fluid moves orthogonally toeards the surface.

For non-flat surfaces, commonly people assume the average angle over the whole surface, when speaking about Angle of Attack.

A perfectly rotation-symmetrical body such as a sphere does not have an angle of attack since the average angle of the surface is non-directional ( vector sum is zero) As such no angle betwern it and the airflow can be computed and the AoA is undefined.

Rockets, eggs, disks, airplane wings and flying cylinder hats all have a primary principal component vector in 3d space. As such AoA is defined and computable.

Its important to note that the sum vector of the surface is not necessarily pointing in the same direction as the principal component of volume. A good counter example are grid fins, which have a dominant surface orientation perpendicular to the apparent shape!

[Herb Schaltegger]

Okay, y'all are giving me flashbacks to undergrad aerodynamics, but honestly, what does all this really have to do with Starlink? Doesn't it really belong in the General Falcon discussion thread?

[Robotbeat]

I think they're going to deploy roughly like this stack of decouplers (with ejection force set to zero) I made in Kerbal Space Program. Spinning about the long axis.

[ArbitraryConstant]

I think they're going to deploy roughly like this stack of decouplers (with ejection force set to zero) I made in Kerbal Space Program. Spinning about the long axis.

Nice visualization.

The comment that the satellites are designed to be able to bump into each other made me picture then releasing more simultaneously.

[Robotbeat]

I think they're going to deploy roughly like this stack of decouplers (with ejection force set to zero) I made in Kerbal Space Program. Spinning about the long axis.

Nice visualization.

The comment that the satellites are designed to be able to bump into each other made me picture then releasing more simultaneously.

Well, as my High Fidelity Simulation shows, the satellites would be spinning as they're released, so a satellite could re-contact the stack as it is released. Likely the whole thing would spin a lot slower than I showed.

[Chris_Pi]

I was thinking an end-over end rotation. The satellites slowly spread out in a line after release. I've attached a video - same zero-force decopuler setup. Lacking your fancy video capture software, I'm making do with something that makes for rather large files. (34 megabytes  )

Either way hopefully we'll get to see it for real in a few hours.

[intelati]

Lacking your fancy video capture software, I'm making do with something that makes for rather large files. (34 megabytes  )

For future reference, you can download Handbrake and make quick work of the 7000 kbps file. I like the Fast presets, I just change the Codec to the NVENC (using your GPU to encode vs your CPU)

[ejb749]

Have we ever seen the SpaceX logo on a fairing before? 

That is a damn good looking rocket.  It's definitely time to start naming the cores.

[AJW]

That raises a question.... Now that fairings are getting reused, do they overpaint the logo from the previous flight, or strip and repaint?  Could these be applied like temporary decals?

[rakaydos]

I was thinking an end-over end rotation. The satellites slowly spread out in a line after release. I've attached a video - same zero-force decopuler setup. Lacking your fancy video capture software, I'm making do with something that makes for rather large files. (34 megabytes  )

Either way hopefully we'll get to see it for real in a few hours.

This does match Elon's description of "spreading a deck of cards"

[ZChris13]

I was thinking an end-over end rotation. The satellites slowly spread out in a line after release. I've attached a video - same zero-force decopuler setup. Lacking your fancy video capture software, I'm making do with something that makes for rather large files. (34 megabytes  )

Either way hopefully we'll get to see it for real in a few hours.

Scott Manley did a similar setup but released them one at a time as he spun, which came out really good
Looking forward to tonight!

[Lar]

Actually, a sphere can have lift if it's spinning.

You're just trying to throw us a curve...

Party thread! (I beat you to that joke)

That raises a question.... Now that fairings are getting reused, do they overpaint the logo from the previous flight, or strip and repaint?  Could these be applied like temporary decals?

We don't know definitively that this fairing is reused. Conventional wisdom is that we will see reused fairings on SOME Starlink mission but not THIS one. So, further discussion is off topic, maybe take it to the fairing reuse thread.

[Robotbeat]

Is there a map showing how far down range the droneship will be and what the ground track looks like? I'm trying to see if I can see the staging or entry burn from south eastern Virginia... It's clear tonight and I have a view down to the horizon.

[MKremer]

The track and recovery positioning should be the same as the previous attempts detailed in the Update thread.

[toruonu]

Is it just me or has by this time at least the funky music usually started... crickets right now...

[intelati]

Is it just me or has by this time at least the funky music usually started... crickets right now...

I pulled up twitter when it hit 14:00

[intelati]

Link to live stream

[sewebster]

The stream wasn't starting for me on youtube so I went to the spacex site and it was working there (via youtube)... not sure what the deal with that is, but in case anyone else is reading this is in the same boat as me, try that...

[Semmel]

Maye a different link? This one works for me.

[Eer]

It's live at https://www.spacex.com/webcast