SpaceX F9 : Crew Dragon In-Flight Abort Test : Jan. 19, 2020 : Discussion

[woods170]

No no. Second stage clearly did not fall with it's terminal velocity, but lot faster in mach numbers e.g. still de-accelerating, same can be true with the trunk. Terminal velocity -> drag = gravity. Did woods170 forget that rockets fly mainly in sideways and not up;P

Terminal velocity is the maximum velocity attainable by an object as it falls through a fluidic medium, in this case air. It occurs when the sum of the drag force and the buoyancy is equal to the downward force of gravity acting on the object.

In case of the trunk it depends what its stable position was. Given the damage to the front end it is likely the trunk came falling down front-first, in which case the terminal velocity would be around 160 km/h (100 mph) but it would also present a "sharp" front edge to "knife"into the water. Given the relative intactness of the trunk it is likely this scenario is what happened.

[HVM]

hey, you can't use that description if aforementioned object is thrown at ~1600km/h to the atmosphere, it's its minimum velocity...  ; )

[mn]

So the object seen escaping forward from the fireball, is presumably the 2nd stage which then apparently fell in one piece.

Is that the consensus? or does anyone have any other theories on that?

[smoliarm]

So the object seen escaping forward from the fireball, is presumably the 2nd stage which then apparently fell in one piece.

Is that the consensus? or does anyone have any other theories on that?

- As I recall, there were two objects (two contrails - thick and thin) going forward from the fireball.
My guess - the *thick* contrail belongs to s2.

[HVM]

1st object: Second stage with interstage and first stage's lox tank's dome and part of wall still attached to the interstage.

2nd object: Thrust structure?

[leetdan]

Look closely, I think you can see the interstage collapsing and separating just before it hits the treeline.  This sudden change could help explain why it detonated above the water

Interstage letting go: https://www.youtube.com/watch?v=K4soghyssxQ?t=546
Detonation: https://www.youtube.com/watch?v=yXqrgaQQ9lo?t=3

[NX-0]

What will become of this particular Dragon? Refurb?

[Swedish chef]

What will become of this particular Dragon? Refurb?

I'm guessing it will end up as an museum piece.

[HVM]

Look closely, I think you can see the interstage collapsing and separating just before it hits the treeline.  This sudden change could help explain why it detonated above the water

Interstage letting go: https://www.youtube.com/watch?v=K4soghyssxQ?t=546
Detonation: https://www.youtube.com/watch?v=yXqrgaQQ9lo?t=3

Ok. Now let's get a good look at you, zoom and let's enhance it.

_{(There's a reflection of the man's face on it?!)}

[Stan-1967]

Those pics remind me of how the sun flattens out to an oval at sunset.

[woods170]

hey, you can't use that description if aforementioned object is thrown at ~1600km/h to the atmosphere, it's its minimum velocity...  ; )

Sure I can. The trunk wasn't released from Dragon until apogee, at 40 km altitude. At apogee the velocity is basically zero. The trunk then began its fall back to the ocean surface. 40 Kilometers of altitude is plenty to have the trunk reach terminal velocity before impact on the ocean surface.

Nobody ever falls upward. At least, not here on Earth ;-)

[woods170]

What will become of this particular Dragon? Refurb?

I'm guessing it will end up as a museum piece.

Possibly will be hung from the ceiling at SpaceX Hawthorne.

[webdan]

What will become of this particular Dragon? Refurb?

I'm guessing it will end up as a museum piece.

Possibly will be hung from the ceiling at SpaceX Hawthorne.

Which means it will, one time only, fly upward.

[HVM]

hey, you can't use that description if aforementioned object is thrown at ~1600km/h to the atmosphere, it's its minimum velocity...  ; )

Sure I can. The trunk wasn't released from Dragon until apogee, at 40 km altitude. At apogee the velocity is basically zero. The trunk then began its fall back to the ocean surface. 40 Kilometers of altitude is plenty to have the trunk reach terminal velocity before impact on the ocean surface.

Nobody ever falls upward. At least, not here on Earth ;-)

Goddamned it's going near ~800km/h horizontal velocity in ballistics trajectory at apogee. And like you said only getting more speed after that, at near vacuum. Or like John Insprucker put it "we're at a high altitude where the aerodynamics are negligible" Last I check +800km/h is more than 160km/h.

The trunk slowed down like feathers shoot from cannon, when it hit the denser part of atmosphere, but only then.

You need to find me The Crew Dragon abort trajectory and show that drag and/or SuperDragos cancel horizontal velocity before or near apogee, and then I agree.

[indaco1]

A fall from 40km is very similar to Felix Baumgartner jump.  Initial horizontal speed doesn't change that much top speed. 

[JamesH65]

hey, you can't use that description if aforementioned object is thrown at ~1600km/h to the atmosphere, it's its minimum velocity...  ; )

Sure I can. The trunk wasn't released from Dragon until apogee, at 40 km altitude. At apogee the velocity is basically zero. The trunk then began its fall back to the ocean surface. 40 Kilometers of altitude is plenty to have the trunk reach terminal velocity before impact on the ocean surface.

Nobody ever falls upward. At least, not here on Earth ;-)

Goddamned it's going near ~800km/h horizontal velocity in ballistics trajectory at apogee. And like you said only getting more speed after that, at near vacuum. Or like John Insprucker put it "we're at a high altitude where the aerodynamics are negligible" Last I check +800km/h is more than 160km/h.

The trunk slowed down like feathers shoot from cannon, when it hit the denser part of atmosphere, but only then.

You need to find me The Crew Dragon abort trajectory and show that drag and/or SuperDragos cancel horizontal velocity before or near apogee, and then I agree.

Was the stage dropping vertically when it hit the water? Yes, as far as I can tell. Or very close to it. This means that ALL that horizontal velocity was lost through drag. All of it. So you only need to take in to account its starting vertical velocity. Which was upwards, and at apogee, 0, so it effectively fell from 40km or whatever apogee was starting at Zero vertical velocity. 40km is plenty of time to reach terminal velocity (which of course is decreasing all the time as it drops as atmosphere become denser). A good analogy would be Blue Origins craft, which drops, unpowered, from well over that sort of height . That falls at terminal velocity.

[ClayJar]

40km is plenty of time to reach terminal velocity (which of course is decreasing all the time as it drops as atmosphere become denser).

Oooh! I remember this episode from last season of "Terminal Velocity Or Not". This is when someone comes in and says that since terminal velocity is decreasing as the falling thing gets closer to the ground, it's going to be falling (slightly/obviously/somewhat/technically) faster than the local terminal velocity (so I can clearly not choose the wine in front of you).

I think perhaps adding an "about" would short circuit the entire subthread, but what reward is there in saying it was falling at about terminal velocity. 

[ZachS09]

Is it just me, or do these two official pictures of SpX-IFA look a bit fake?

I think it looks like someone made a detailed painting of the abort.

[ugordan]

It's low resolution imagery that's been upscaled and contrast-enhanced to get rid of atmospheric/cloud haze. Looks perfectly legit to me.

[Confusador]

What will become of this particular Dragon? Refurb?

I'm guessing it will end up as a museum piece.

Possibly will be hung from the ceiling at SpaceX Hawthorne.

I'm willing to bet that between the time they finish inspecting it and when it finds its final rest, it gets used for parachute system tests.