Author Topic: SpaceX Falcon Heavy Demo - Discussion and Speculation  (Read 135875 times)

Offline Ictogan

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Re: SpaceX Falcon Heavy Demo - Discussion and Speculation
« Reply #500 on: 09/01/2017 11:27 AM »
Not to re-open a can of worms, but does anybody know WHEN they might announce what the demo "payload" is? Or will it remain "under wraps"  ::) until after the flight like the cheese?

Someone needs to check with Blue Bird, IC Bus, and Thomas Built to see if any yellow school busses have been delivered to SpaceX

I'm hoping they'll launch a Tesla.

What's going to be on top of the second stage?

Alternatives are presumably a (used) Dragon or a payload fairing, with a mass simulator inside it. Both are going to be costly.

The advantage of a Dragon would be that they'd almost certainly get it back; and it could return a payload. There's surely a market for flying a Dragon loaded with a decent weight in commemorative coins (or similar) and selling them off after they've been recovered?
I seem to recall that only launches with fairings count towards certification for national security launches, so it will likely be with a fairing. I can't find a source for this though, so I would appreciate if someone could confirm this or correct me.

Also Dragon probably couldn't land if it was loaded to anywhere near FH capability. You could still use the trunk for mass simulators though.

Offline OneSpeed

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Re: SpaceX Falcon Heavy Demo - Discussion and Speculation
« Reply #501 on: 09/01/2017 11:44 AM »
A lot of the energy will come from the moon itself.

True as it's a free return mission. Isn't the distance from the Earth intended to be greater than any of the Apollo missions achieved, if it is why have they chosen that as won't the re-entry speed to the Earth also be consequently higher?

There are two classes of free return trajectories. Those that pass 'in front' of the moon to reduce velocity, and return immediately to Earth (e.g. Apollo), and those that pass 'behind' the moon's trajectory to obtain a gravity assist or 'kick', and continue beyond the moon's orbit. The tourist lunar flyby would top out at 480-650,000 kms, and so be in the second category. The return velocity from the former peaks at 10.8 km/s, from the latter at around 11.2 km/s. Higher, but not a huge difference. A good test though.

Offline Star One

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Re: SpaceX Falcon Heavy Demo - Discussion and Speculation
« Reply #502 on: 09/01/2017 01:56 PM »
A lot of the energy will come from the moon itself.

True as it's a free return mission. Isn't the distance from the Earth intended to be greater than any of the Apollo missions achieved, if it is why have they chosen that as won't the re-entry speed to the Earth also be consequently higher?

There are two classes of free return trajectories. Those that pass 'in front' of the moon to reduce velocity, and return immediately to Earth (e.g. Apollo), and those that pass 'behind' the moon's trajectory to obtain a gravity assist or 'kick', and continue beyond the moon's orbit. The tourist lunar flyby would top out at 480-650,000 kms, and so be in the second category. The return velocity from the former peaks at 10.8 km/s, from the latter at around 11.2 km/s. Higher, but not a huge difference. A good test though.

Is it possible to calculate, I am assuming it is, what kind of temperatures the Dragon's re-entry shield is likely to be exposed to on the mission?

Online envy887

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Re: SpaceX Falcon Heavy Demo - Discussion and Speculation
« Reply #503 on: 09/01/2017 03:25 PM »
They dont expect any circumstance where the center core will ever be RTLS. Too far downrange to come back.


The last launch had a pretty lofted trajectory.  I would never say never.

I'd of thought the commercial manned lunar mission would preclude recovering the cores due to the requirements of the mission.

Not necessarily. They might be able to recover all three cores.

But surely it's an extremely high energy mission plus you want plenty of margin in performance when you're trying to maximise the safety and chances success for your passengers.


There aren't a lot of scenarios where expending the booster(s) increases useful margins. If there's a performance issue with a booster, FH can use landing fuel to make up the difference.

But once the upper stage and Dragon are in LEO, it's all up to the upper stage - a major performance shortfall from the MVac would likely result in Dragon returning early. Dragon 2 has a considerable amount of abort fuel that can be used to modify the trajectory for a quicker return post-TLI or in the event of an aborted or short injection.

Offline 321_SNI

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Re: SpaceX Falcon Heavy Demo - Discussion and Speculation
« Reply #504 on: 09/01/2017 07:56 PM »
Not to re-open a can of worms, but does anybody know WHEN they might announce what the demo "payload" is? Or will it remain "under wraps"  ::) until after the flight like the cheese?

We had heard that the Planetary Society's Solar Sail was to go on the first Falcon Heavy, at least that was the talk a year ago or two.

That's on the STP-2 mission, which was never the first flight.

Thanks, Gongora (and phil1776)!  Great to hear your info.  This might be like a technicality.  But I really remember them saying that the awesome solar saill project of the Planetary Society was going on the maiden flight of FH, back then.  We thought that was so cool, so appropriate and fitting to have those two cutting edge organizations right together in making history (www.planetary.org and Spacex).  But I also cringed at it going on the FH debut when I heard that, with the possibility of a repeat of Planetary's launch from Russia!  Maybe this weekend I can track down some articles on whether they really had been thinking of going up, on the debut flight.  But thanks again, just love all your Spacex discussions -- and about FH especially, as the excitement draws nearer!!  :)


Offline cscott

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Re: SpaceX Falcon Heavy Demo - Discussion and Speculation
« Reply #505 on: 09/02/2017 03:37 PM »
The lightsail is currently planned to be the third FH mission.  Another mission jumped the line to be #2. As I mentioned, I got tickets to watch that launch by supporting the lightsail Kickstarter.

Offline 321_SNI

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Re: SpaceX Falcon Heavy Demo - Discussion and Speculation
« Reply #506 on: 09/02/2017 05:12 PM »
The lightsail is currently planned to be the third FH mission.  Another mission jumped the line to be #2. As I mentioned, I got tickets to watch that launch by supporting the lightsail Kickstarter.

Glad to see your involvement, Cscott.   Lightsail is  a project which at one time seemed like a wild, far reach for just a grassroots group – kind of like a guy starting his own rocket company from scratch and going on to engineer the first reusable commercial rockets!  Did you join in the kickstarter a few years ago, and do you recall if there was talk of them going on the debut FH flight?  In any case, its cool to talk about this sci-fi sounding stuff, now going forward with visionary Spacex.  Btw, haven’t seen the schedule lately, but I recall that FH’s will be going strong after a successful debut.  #4 is for ’18, right?  Hope you have a good location with your tickets  (and have a great launch!).

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