Author Topic: Falcon Heavy Demo Mission Payload Speculation  (Read 97479 times)

Offline OneSpeed

  • Full Member
  • ****
  • Posts: 539
  • Liked: 570
  • Likes Given: 458
Falcon Heavy Demo Mission Payload Speculation
« on: 04/25/2017 03:48 AM »
If the Falcon Heavy Demo Mission flies this year, there is not much time to develop a payload. Elon Musk has suggested that a Dragon heat shield could be adapted for a 'Hail Mary' attempt at landing a Falcon second stage. What would be the simplest way to provide this configuration from existing parts?

One alternative would be to use an existing Dragon, possibly outfitted with Super Draco engines for landing, fixed to the PAF, enclosed in the payload fairing. The C of G would be well forward of centre, and the payload fairings would be validated on Falcon Heavy. Although there would be no useful payload to orbit, it could be a valuable proof of concept for S2 EDL, regardless of whether or not landing is successful.
« Last Edit: 04/25/2017 03:49 AM by OneSpeed »

Offline FishInferno

  • Member
  • Posts: 95
  • Liked: 39
  • Likes Given: 83
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #1 on: 04/25/2017 03:51 AM »
That is an... interesting, at best, proposal for S2 recovery.  It does, however, seem possible that a Dragon could be mounted inside the fairing like this for a circumlunar flight, while still keeping fairing validation for the USAF.
Comparing SpaceX and SLS is like comparing paying people to plant fruit trees with merely digging holes and filling them.  - Robotbeat

Offline Zed_Noir

  • Senior Member
  • *****
  • Posts: 2240
  • Canada
  • Liked: 287
  • Likes Given: 452
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #2 on: 04/25/2017 04:09 AM »
That is an... interesting, at best, proposal for S2 recovery.  It does, however, seem possible that a Dragon could be mounted inside the fairing like this for a circumlunar flight, while still keeping fairing validation for the USAF.
Doesn't SX have the pad abort demo Dragon available? Just need a heat shield for reentry test from circumlunar loop.

Offline matt_ellis

  • Member
  • Posts: 9
  • Woking, Surrey, UK
  • Liked: 11
  • Likes Given: 0
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #3 on: 04/25/2017 04:49 AM »
While I have no evidence to support this, I would be surprised if SpaceX/EM had not been planning (at least in outline) the payload for the first FH since It was conceived.

Having said that, given the recent manned circumlunar announcement (which would have gone through the initial planning phase before the announcement was made), and factoring in the combination of parts commonality that SpaceX prefers plus their rapid development abilities, I could see a 'dry run' of the moon mission being attempted (or at least testing of components for it).

And there will be cheese!

As regards the S2 landing, at least one six+ year old SpaceX video shows how they envisioned this, so again I would suspect reasonably advanced designs, and with their aforementioned abilities/parts reuse I can see them trying something along those lines (and just because EM tweets about something, does not mean he had just thought of it, more likely given how he uses Twitter etc. It was already in the planning and he tweeted once plans were advanced enough).

I guess the limiting factor would be human resources to do all the work.

Offline Roy_H

  • Full Member
  • ****
  • Posts: 719
  • Liked: 184
  • Likes Given: 1177
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #4 on: 04/25/2017 04:04 PM »
If the Falcon Heavy Demo Mission flies this year, there is not much time to develop a payload.

As noted above, a false assumption. SpaceX has had years to decide on and develop a payload. They have even refused to launch someone else's payload so the statement that it will be just a mass simulator does not add up to me.
"If we don't achieve re-usability, I will consider SpaceX to be a failure." - Elon Musk

Offline whitelancer64

Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #5 on: 04/25/2017 04:14 PM »
I don't think a Dragon is silly enough:

https://twitter.com/elonmusk/status/847884351375372288
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
"There are lies, damned lies, and launch schedules." - Larry J

Offline envy887

  • Senior Member
  • *****
  • Posts: 2771
  • Liked: 1277
  • Likes Given: 805
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #6 on: 04/25/2017 05:32 PM »
If the Falcon Heavy Demo Mission flies this year, there is not much time to develop a payload.

As noted above, a false assumption. SpaceX has had years to decide on and develop a payload. They have even refused to launch someone else's payload so the statement that it will be just a mass simulator does not add up to me.

A mass simulator or boilerplate spacecraft makes perfect sense. SpaceX has plenty to work on just getting FH flying with no payload on it.

Offline OneSpeed

  • Full Member
  • ****
  • Posts: 539
  • Liked: 570
  • Likes Given: 458
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #7 on: 04/25/2017 09:58 PM »
... SpaceX has had years to decide on and develop a payload ...

I should have been clearer. There has been some speculation that a payload that is a closer analogue to BFS could be launched on the FH. I agree with that, but I'm also saying that I don't think there is time for that to happen on the demo flight.

I don't think a Dragon is silly enough.

It's not, but its payload could be.

Edit: Upside-down cake?

A mass simulator or boilerplate spacecraft makes perfect sense. SpaceX has plenty to work on just getting FH flying with no payload on it.

But they have said there will be a 'Hail Mary' attempt to return a second stage on the demo flight. How would a mass simulator or boilerplate spacecraft help with that?
« Last Edit: 04/25/2017 11:42 PM by OneSpeed »

Offline rpapo

  • Cybernetic Mole
  • Full Member
  • ****
  • Posts: 1057
  • Michigan, USA
  • Liked: 478
  • Likes Given: 403
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #8 on: 04/25/2017 10:02 PM »
But they have said there will be a 'Hail Mary' attempt to return a second stage on the demo flight.
Funny how "may be" becomes "will be" in the private little game of "Telephone" we have going on here...
An Apollo fanboy . . . fifty years ago.

Offline OneSpeed

  • Full Member
  • ****
  • Posts: 539
  • Liked: 570
  • Likes Given: 458
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #9 on: 04/25/2017 10:04 PM »
But they have said there will be a 'Hail Mary' attempt to return a second stage on the demo flight.
Funny how "may be" becomes "will be" in the private little game of "Telephone" we have going on here...

Fair enough, "may be". Still, the question is, how could it be done?

Offline Jcc

  • Full Member
  • ****
  • Posts: 818
  • Liked: 179
  • Likes Given: 77
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #10 on: 04/25/2017 11:38 PM »
I think they should launch all the Google Lunar X prize entrants at once.
In addition to a mass simulator, because that would still be too light.
« Last Edit: 04/25/2017 11:39 PM by Jcc »

Offline envy887

  • Senior Member
  • *****
  • Posts: 2771
  • Liked: 1277
  • Likes Given: 805
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #11 on: 04/26/2017 12:42 AM »
But they have said there will be a 'Hail Mary' attempt to return a second stage on the demo flight.
Funny how "may be" becomes "will be" in the private little game of "Telephone" we have going on here...

Fair enough, "may be". Still, the question is, how could it be done?

However they plan to recover the upper stage has to be compatible with real payloads or it's pretty useless. So go up with a simulator, sep, and come back without it.

Online hpras

  • Member
  • Posts: 58
  • Liked: 23
  • Likes Given: 3
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #12 on: 04/26/2017 05:12 AM »
One bajillion cubesats?

Offline OneSpeed

  • Full Member
  • ****
  • Posts: 539
  • Liked: 570
  • Likes Given: 458
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #13 on: 04/26/2017 12:04 PM »
However they plan to recover the upper stage has to be compatible with real payloads or it's pretty useless. So go up with a simulator, sep, and come back without it.

The topic of this thread is not the long term plan for S2 re-use. Rather, it is asking what could realistically be achieved by the FH demo mission. If the mission could provide new data regarding the re-entry from orbit of a Falcon second stage, then it would have been anything but useless. If it could return a second stage, even if damaged, even with a 'silly' payload, the results obtained would be invaluable. Those results would inform the longer term design of a truly re-usable second stage.

If you were to just 'go up with a simulator, and separate', how would you then return the second stage? Where on the upper stage would be the Dragon heatshield? How would you provide thrust, both for attitude control, and for landing? Would it have a moveable mass for controlling AoA? Would it have landing legs? What would be the flight control system? How would you create all of these new features before the FH demo launch? 

To my mind, using the Dragon2 to provide all of this functionality massively simplifies the problem, and does so in the shortest possible timeframe. But I'm keen to listen to any alternatives.

Offline coal_burner

  • Member
  • Posts: 23
  • Liked: 12
  • Likes Given: 113
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #14 on: 04/26/2017 12:20 PM »
what if they were to build an instrumented boilerplate 2nd stage with a heat shield, thrusters, and just an mvac mockup, and carried that up inside the payload fairing.

that would allow them to get data on a cylindrical reentry vehicle without the risk of a 2nd stage failure due to reentry modifications.

I'm pretty sure that launching a 2nd stage on top of a 2nd stage counts as pretty silly.

Offline envy887

  • Senior Member
  • *****
  • Posts: 2771
  • Liked: 1277
  • Likes Given: 805
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #15 on: 04/26/2017 12:52 PM »
However they plan to recover the upper stage has to be compatible with real payloads or it's pretty useless. So go up with a simulator, sep, and come back without it.

The topic of this thread is not the long term plan for S2 re-use. Rather, it is asking what could realistically be achieved by the FH demo mission. If the mission could provide new data regarding the re-entry from orbit of a Falcon second stage, then it would have been anything but useless. If it could return a second stage, even if damaged, even with a 'silly' payload, the results obtained would be invaluable. Those results would inform the longer term design of a truly re-usable second stage.

If you were to just 'go up with a simulator, and separate', how would you then return the second stage? Where on the upper stage would be the Dragon heatshield? How would you provide thrust, both for attitude control, and for landing? Would it have a moveable mass for controlling AoA? Would it have landing legs? What would be the flight control system? How would you create all of these new features before the FH demo launch? 

To my mind, using the Dragon2 to provide all of this functionality massively simplifies the problem, and does so in the shortest possible timeframe. But I'm keen to listen to any alternatives.

The second stage already has avionics and a RCS system. It will need some mods for recovery, like a parachute, some extra TPS for the side walls, and probably rear flaps, so it's not like they can claim it's a standard upper stage. They may be bolt-on mods like the S1 recovery hardware, but the stage function still has to be validated with them.

If they do use an upside-down Dragon 2 heatshield with its legs, tanks, and superdracos, they still need some way to mount the payload adapter on top - likely using the Dragon-to-trunk fittings and discarding the payload adapter before reentry. And they need to show that the payload adapter works with all the new stuff under it. The only way to do that is to carry a realistic massive payload up and demonstrate separation. Thus: carry a mass simulator up, separate, return the stage.
« Last Edit: 04/26/2017 12:53 PM by envy887 »

Offline envy887

  • Senior Member
  • *****
  • Posts: 2771
  • Liked: 1277
  • Likes Given: 805
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #16 on: 04/26/2017 12:55 PM »
what if they were to build an instrumented boilerplate 2nd stage with a heat shield, thrusters, and just an mvac mockup, and carried that up inside the payload fairing.

that would allow them to get data on a cylindrical reentry vehicle without the risk of a 2nd stage failure due to reentry modifications.

I'm pretty sure that launching a 2nd stage on top of a 2nd stage counts as pretty silly.

The current second stage is about twice as long as anything that will fit in the fairing, so a boilerplate upper stage launched faired wouldn't look or fly like the real thing.

Offline OneSpeed

  • Full Member
  • ****
  • Posts: 539
  • Liked: 570
  • Likes Given: 458
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #17 on: 04/26/2017 01:50 PM »
The second stage already has avionics and a RCS system. It will need some mods for recovery, like a parachute, some extra TPS for the side walls, and probably rear flaps, so it's not like they can claim it's a standard upper stage. They may be bolt-on mods like the S1 recovery hardware, but the stage function still has to be validated with them.

It still sounds like you are describing the end game, rather than a test article.

Why would it need a parachute?
How do you know extra TPS is required? It might be required on the PAF, but the side walls would be well away from the radiant heat of the hypersonic bow shock.
Why would it would need rear flaps? The Dragon2 has thrusters and a moveable mass.

If they do use an upside-down Dragon 2 heatshield with its legs, tanks, and superdracos, they still need some way to mount the payload adapter on top - likely using the Dragon-to-trunk fittings and discarding the payload adapter before reentry. And they need to show that the payload adapter works with all the new stuff under it. The only way to do that is to carry a realistic massive payload up and demonstrate separation. Thus: carry a mass simulator up, separate, return the stage.

Whilst I agree that something along the lines of the existing Dragon to trunk fittings could be used to mount the payload adapter, why do they need to show that working on the demo flight? Wouldn't simply recovering the stage be a huge achievement?

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 31351
  • Cape Canaveral Spaceport
  • Liked: 9628
  • Likes Given: 299
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #18 on: 04/26/2017 01:53 PM »


To my mind, using the Dragon2 to provide all of this functionality massively simplifies the problem, and does so in the shortest possible timeframe. But I'm keen to listen to any alternatives.

It does none of those things as explained before.  Dragon is not flying in a fairing.
« Last Edit: 04/26/2017 01:55 PM by Jim »

Offline OneSpeed

  • Full Member
  • ****
  • Posts: 539
  • Liked: 570
  • Likes Given: 458
Re: Falcon Heavy Demo Mission Payload Speculation
« Reply #19 on: 04/26/2017 02:01 PM »
It does none of those things as explained before.  Dragon is not flying in a fairing.

Which explanation are you referring to? Are you saying Dragon could not be launched in a fairing?

Tags: