Author Topic: Falcon Heavy and Starman documentary  (Read 3923 times)

Offline Llian Rhydderch

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Falcon Heavy and Starman documentary
« on: 03/10/2018 11:23 PM »
This was just released, after showing live today at South by Southwest (SXSW) in Austin, Texas.

(with Elon Musk and the filmmakers present)



Elon Musk on Twitter:
Quote
Why Falcon Heavy & Starman?

Life cannot just be about solving one sad problem after another. There need to be things that inspire you, that make you glad to wake up in the morning and be part of humanity. That is why we did it. We did for you.


Edit:  added quote of Musk's Twitter post, and link to the video on SpaceX' YouTube channel
« Last Edit: 03/11/2018 01:06 AM by Llian Rhydderch »
Re arguments from authority on NSF:  "no one is exempt from error, and errors of authority are usually the worst kind.  Taking your word for things without question is no different than a bracket design not being tested because the designer was an old hand."
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Offline fthomassy

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Re: Falcon Heavy and Starman documentary
« Reply #1 on: 03/10/2018 11:34 PM »
This was just released, after showing live today at South by Southwest (SXSW) in Austin, Texas.

(with Elon Musk and the filmmakers present)

Falcon Heavy & Starman
Awesome splashdown of the core!
gyatm . . . Fern

Offline AC in NC

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Re: Falcon Heavy and Starman documentary
« Reply #2 on: 03/10/2018 11:51 PM »
I cried. 

Big softy for that kind of stuff.

Offline RocketLover0119

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Re: Falcon Heavy and Starman documentary
« Reply #3 on: 03/11/2018 12:08 AM »
One thing I noticed is that during the center core landing attempt, the legs did not deploy, not sure if hardware issue?
"The Falcon has landed"

Offline DnA915

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Re: Falcon Heavy and Starman documentary
« Reply #4 on: 03/11/2018 12:18 AM »
It was coming in really hot from not having the engine light. They usually deploy those as its slowing for final landing. It was likely not time to have them deploy. I've read also that they do not line it up with the ship until final approach. As it likely knew it was bailing, it would make sense to lower it impact point to lower risk to the ship too.

Offline Llian Rhydderch

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Re: Falcon Heavy and Starman documentary
« Reply #5 on: 03/11/2018 12:44 AM »
Video is unlisted so obviously not meant to be seen by general viewers yet.

Hopefully the OP won't get burned for this...

It was shared on Twitter by Elon so I think OP will be fine.

Yes, just used the link to the video that Musk shared on his twitter account.
Re arguments from authority on NSF:  "no one is exempt from error, and errors of authority are usually the worst kind.  Taking your word for things without question is no different than a bracket design not being tested because the designer was an old hand."
"You would actually save yourself time and effort if you were to use evidence and logic to make your points instead of wrapping yourself in the royal mantle of authority.  The approach only works on sheep, not inquisitive, intelligent people."

Offline jedsmd

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Re: Falcon Heavy and Starman documentary
« Reply #6 on: 03/11/2018 01:47 AM »
One thing I noticed is that during the center core landing attempt, the legs did not deploy, not sure if hardware issue?

Interesting, I wonder if when the engine start failed it went into some sort of ditch mode?

Offline mme

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Re: Falcon Heavy and Starman documentary
« Reply #7 on: 03/11/2018 02:16 AM »
One thing I noticed is that during the center core landing attempt, the legs did not deploy, not sure if hardware issue?

Interesting, I wonder if when the engine start failed it went into some sort of ditch mode?
My guess is that the legs probably deploy at a specific altitude and in this case there just wasn't time.
Space is not Highlander.  There can, and will, be more than one.

Offline philw1776

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Re: Falcon Heavy and Starman documentary
« Reply #8 on: 03/11/2018 03:05 PM »
One thing I noticed is that during the center core landing attempt, the legs did not deploy, not sure if hardware issue?

i doubt it.  Informed speculation here and elsewhere has landing cores lined up to miss UNTIL velocity, altitude, engine and maybe propellant gates are all GO for landing.  The large velocity, engine indicators and low altitude at velocity likely did not enable the deploy legs routine and did not make the final corrections to landing target.
Interesting that the miss distance was insufficient to prevent damage to the ship's thrusters when the core detonated underwater.
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Offline Barrie

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Re: Falcon Heavy and Starman documentary
« Reply #9 on: 03/11/2018 04:03 PM »
iirc the deceleration of the landing burn helps to deploy the legs, so maybe there wasn't sufficient deceleration for leg deploy

Offline John Alan

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Re: Falcon Heavy and Starman documentary
« Reply #10 on: 03/11/2018 04:26 PM »
Say your writing the base code the stage uses for landing...
One requirement (I am assuming this) is try and miss the barge, if all is not well...  :-\

Would your code not include some lines that inhibits leg deploy IF all is not well?...  ???

I would...  :D

If your trying to miss something, you would try and keep your outline as small as possible...
Having your landing legs hanging out 30+ft on all sides is the LAST thing you want if your trying to miss something.

Just my 2 cents on subtopic...  ;)

On topic... I really like the video as released... great PR...  8)
« Last Edit: 03/11/2018 04:28 PM by John Alan »

Offline Torbjorn Larsson, OM

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Re: Falcon Heavy and Starman documentary
« Reply #11 on: 03/11/2018 04:28 PM »
iirc the deceleration of the landing burn helps to deploy the legs, so maybe there wasn't sufficient deceleration for leg deploy

IIRC there has been speculation along those lines, but no evidence offered, right?

The core taking the decision that further course corrections and deploying legs is futile/increase damage around landing platform seems reasonable to me.

Online RotoSequence

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Re: Falcon Heavy and Starman documentary
« Reply #12 on: 03/11/2018 04:46 PM »
Interesting that the miss distance was insufficient to prevent damage to the ship's thrusters when the core detonated underwater.

I don't think there was any tankage left to detonate; The core going into the sea was uncomfortably reminiscent of 9/11 and seeing 767s disappear into the World Trade Center, but without the fuel explosion after the RP1 tank's contents were rapidly distributed into the sea.

Online meekGee

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Re: Falcon Heavy and Starman documentary
« Reply #13 on: 03/11/2018 05:29 PM »
Interesting that the miss distance was insufficient to prevent damage to the ship's thrusters when the core detonated underwater.

I don't think there was any tankage left to detonate; The core going into the sea was uncomfortably reminiscent of 9/11 and seeing 767s disappear into the World Trade Center, but without the fuel explosion after the RP1 tank's contents were rapidly distributed into the sea.

You'll need a high speed camera to really figure out what's going on there.

There's a leading rigid mass (engine structure) followed by two elongated pressurized cylinders.  One of them may have made it under water and exploded there, or maybe just the impact caused a shock wave.
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Offline philw1776

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Re: Falcon Heavy and Starman documentary
« Reply #14 on: 03/11/2018 05:49 PM »
Interesting that the miss distance was insufficient to prevent damage to the ship's thrusters when the core detonated underwater.

I don't think there was any tankage left to detonate; The core going into the sea was uncomfortably reminiscent of 9/11 and seeing 767s disappear into the World Trade Center, but without the fuel explosion after the RP1 tank's contents were rapidly distributed into the sea.

No.  There should have been plenty propellant to detonate since only 1/3rd of the landing engines fired.
The undersea detonation took out a couple of the ships motors.
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Offline Hobbes-22

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Re: Falcon Heavy and Starman documentary
« Reply #15 on: 03/11/2018 06:38 PM »
The damage could have been caused by the shockwave from the impact or from the tanks rupturing (as they're still pressurized at that point), or the LOX expanding when it comes into contact with seawater. My bet is on the last.

An explosion would require the RP and LOX to mix without too much seawater getting in the way. (something like the bulkhead giving way while the outside of the stage stays intact)

Offline speedevil

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Re: Falcon Heavy and Starman documentary
« Reply #16 on: 03/11/2018 06:46 PM »
An explosion would require the RP and LOX to mix without too much seawater getting in the way. (something like the bulkhead giving way while the outside of the stage stays intact)

The impact was at 180MPH or so, from measurements, 80m/s ish.
That is somewhat north of 500kg of propellant.
At least 400kg of liquid oxygen.

In comparison, the stage weighs 20 tons.

Offline Nomadd

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Re: Falcon Heavy and Starman documentary
« Reply #17 on: 03/11/2018 06:48 PM »
 The Thrustmasters I worked with blew seals pretty easily if anything interfered with the prop. Maybe a shockwave was enough.

Offline ChrML

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Re: Falcon Heavy and Starman documentary
« Reply #18 on: 03/11/2018 08:55 PM »
Would your code not include some lines that inhibits leg deploy IF all is not well?...  ???
Depends. Additional risk/sideeffect is that the only thing causing the landing to fail is that the rocket thought something was wrong and did not deploy the landing gear. Only reason to add that code is if the benefit of crashing the core without legs deployed, exceed the risk of adding additional scenarios.

Every scenario has to be carefully evaluated, and for the lowest possible overall risk, you want as clean sequence as possible with the least number of eventualities.

Offline aero

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Re: Falcon Heavy and Starman documentary
« Reply #19 on: 03/11/2018 10:59 PM »
You might ask yourself, "What happens to the aerodynamic stability if the legs are deployed at 180 mph and the resulting shift in the center of pressure."

I don't know how quickly the vehicle guidance would lose control but it would be too quick to allow it to happen in the general case.
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Offline RoboGoofers

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Re: Falcon Heavy and Starman documentary
« Reply #20 on: 03/12/2018 03:18 PM »
You might ask yourself, "What happens to the aerodynamic stability if the legs are deployed at 180 mph and the resulting shift in the center of pressure."

I don't know how quickly the vehicle guidance would lose control but it would be too quick to allow it to happen in the general case.

The drag on the legs, alone, might have prevented deployment. initial deployment has very little leverage, and they likely designed the leg pistons to only overcome the drag force of a typical landing.
« Last Edit: 03/12/2018 03:34 PM by RoboGoofers »

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