Author Topic: SpaceX Falcon Heavy Demo - Discussion and Speculation (Read 229833 times)

gongora · « **Reply #40 on:** 02/08/2017 02:53 am »

Quote from: IanThePineapple on 02/08/2017 01:50 am

I'm certain they won't have a Dragon onboard FH Demo, but it's cool to theorize.

Someplace other than the mission thread would be a better place to theorize about unrelated subjects.

alang · « **Reply #41 on:** 02/08/2017 04:11 am »

Quote from: Robotbeat on 02/08/2017 01:04 am

I believe the announcement that "never materialized" is Red Dragon (which did materialize).

Anyway, qualifying the Dragon heatshield for high speed reentry would be a useful demo payload. Doesn't necessarily have to go all the way around the Moon, just a very high (near escape) Earth orbit. Or possibly not that high, but using a second burn of the upper stage to accelerate the Dragon after sent on an initial lofting trajectory. That way, it wouldn't need solar arrays, just batteries, since the duration would be shorter.

Dumb battery calculation:
One published dragon payload mass estimate says 6 metric ton launch payload and 3 metric ton return payload.
One published power rating of dragon solar arrays says circa 2000W.
Six day free return mission would generate circa 300 Kilowatt hours.
I've seen a 5 kWh lithium ion battery specified as 60 kilos.
So circa 4 metric tons of batteries if you needed that much power if my arithmetic is correct.
Another manufacturer of batteries who makes them for cars quotes them at roughly half that mass per kWh.
Does that seem right and what would that mean for cooling?
Would this be a useful mass emulator in a used dragon for a battery manufacturer who wanted to make a point?
More expensive than a cheese though.

Kaputnik · « **Reply #42 on:** 02/08/2017 07:22 am »

You can half your power requrements straight off, since this Dragon wouldn't be spending half it's time in Earth's shadow.

Proponent · « **Reply #43 on:** 02/08/2017 08:23 am »

I wonder whether SpaceX might worry that a circumlunar Dragon flight, cool though it would be, if it's possible, would embarrass NASA. Not a good idea to embarrass your largest customer.

yokem55 · « **Reply #44 on:** 02/08/2017 08:58 am »

Quote from: Proponent on 02/08/2017 08:23 am

I wonder whether SpaceX might worry that a circumlunar Dragon flight, cool though it would be, if it's possible, would embarrass NASA. Not a good idea to embarrass your largest customer.

That's why I don't think it would be circumlunar. Just send it far enough out to get an entry speed that they would see on entry at mars for Red Dragon. Also validate the deep space avionics and DSN tracking and up/downlink for Red Dragon. It doesn't have to be a full Dragon 2 build, a previously flown dragon with Dragon 2 avionics and a Red Dragon scale heat shield would do the trick.

jpo234 · « **Reply #45 on:** 02/08/2017 09:09 am »

Quote from: Proponent on 02/08/2017 08:23 am

I wonder whether SpaceX might worry that a circumlunar Dragon flight, cool though it would be, if it's possible, would embarrass NASA. Not a good idea to embarrass your largest customer.

Why would sending an unmanned vehicle around the Moon embarrass NASA? Apollo 8 did this (manned) in 1968 and most recently they sent Orion on a similar test in 2014.

Proponent · « **Reply #46 on:** 02/08/2017 09:27 am »

NASA no longer has the capability it had in 1968. It now speaks of sending a craft capable of carrying a crew around the moon (EM-1) in 2021 (EM-1). A circumlunar Dragon flight would make SpaceX look four years ahead of NASA in significant ways.

kch · « **Reply #47 on:** 02/08/2017 09:41 am »

Quote from: jpo234 on 02/08/2017 09:09 am

Quote from: Proponent on 02/08/2017 08:23 am
I wonder whether SpaceX might worry that a circumlunar Dragon flight, cool though it would be, if it's possible, would embarrass NASA. Not a good idea to embarrass your largest customer.

Why would sending an unmanned vehicle around the Moon embarrass NASA? Apollo 8 did this (manned) in 1968 and most recently they sent Orion on a similar test in 2014.

The EFT-1 flight in 2014 didn't get anywhere near the Moon -- 3600 miles is a whole lot less than a quarter-million:

https://en.wikipedia.org/wiki/Exploration_Flight_Test_1

jpo234 · « **Reply #48 on:** 02/08/2017 09:46 am »

Quote from: Proponent on 02/08/2017 09:27 am

NASA no longer has the capability it had in 1968. It now speaks of sending a craft capable of carrying a crew around the moon (EM-1) in 2021 (EM-1). A circumlunar Dragon flight would make SpaceX look four years ahead of NASA in significant ways.

A circumlunar Dragon flight would test FH and Dragon for the Red Dragon mission planned for next year. Everything we know indicates that NASA is excited and not embarrassed about Red Dragon; after all, they provide support.

jpo234 · « **Reply #49 on:** 02/08/2017 09:48 am »

Quote from: kch on 02/08/2017 09:41 am

Quote from: jpo234 on 02/08/2017 09:09 am
Why would sending an unmanned vehicle around the Moon embarrass NASA? Apollo 8 did this (manned) in 1968 and most recently they sent Orion on a similar test in 2014.
The EFT-1 flight in 2014 didn't get anywhere near the Moon -- 3600 miles is a whole lot less than a quarter-million:
https://en.wikipedia.org/wiki/Exploration_Flight_Test_1

You are right. I only remembered that it was similar to one of the Apollo tests and just assumed that it was circumlunar.

rpapo · « **Reply #50 on:** 02/08/2017 10:05 am »

Quote from: Jim on 02/08/2017 02:42 am

Quote from: deltaV on 02/08/2017 01:18 am
Dragon may not be intended to every leave the Earth/Moon system.

It might not even be design to be capable of leaving LEO

By that, do you mean unable to function without GPS, unable to deal with the higher radiation doses through the Van Allen belts and beyond, insufficient communications capability or something else entirely?

Jet Black · « **Reply #51 on:** 02/08/2017 01:05 pm »

What modifications will they have had to make to the cores if these are re-used boosters? I recall that the center core had to be strengthened and no doubt there will be holds on the side cores, but are there other modifications that are likely to be needed?

regarding the launch, I expect that the launch won't be too taxing on the system since they will almost certainly want to recover boosters.

matthewkantar · « **Reply #52 on:** 02/08/2017 01:49 pm »

Quote from: Proponent on 02/08/2017 08:23 am

I wonder whether SpaceX might worry that a circumlunar Dragon flight, cool though it would be, if it's possible, would embarrass NASA. Not a good idea to embarrass your largest customer.

SpaceX is planning to send the same spacecraft all the way to Mars next year, with help from NASA. Why would there be any embarrassment about a lunar flyby?

Matthew

Jim · « **Reply #53 on:** 02/08/2017 01:54 pm »

Quote from: rpapo on 02/08/2017 10:05 am

Quote from: Jim on 02/08/2017 02:42 am
Quote from: deltaV on 02/08/2017 01:18 am
Dragon may not be intended to every leave the Earth/Moon system.

It might not even be design to be capable of leaving LEO
By that, do you mean unable to function without GPS, unable to deal with the higher radiation doses through the Van Allen belts and beyond, insufficient communications capability

Yes

woods170 · « **Reply #54 on:** 02/08/2017 01:54 pm »

Quote from: matthewkantar on 02/08/2017 01:49 pm

Quote from: Proponent on 02/08/2017 08:23 am
I wonder whether SpaceX might worry that a circumlunar Dragon flight, cool though it would be, if it's possible, would embarrass NASA. Not a good idea to embarrass your largest customer.

SpaceX is planning to send the same spacecraft all the way to Mars three years from now ~~next year~~, with help from NASA. Why would there be any embarrassment about a lunar flyby?

Matthew

There, fixed that for ya. I've been informed that 2018 is off the table. Remember, 2018 was only a NET.

abaddon · « **Reply #55 on:** 02/08/2017 01:58 pm »

Quote from: woods170 on 02/08/2017 01:54 pm

There, fixed that for ya. I've been informed that 2018 is off the table. Remember, 2018 was only a NET.

No surprise, the 2018 date was a pipe dream with everything they have on their plate that is more important.

ElGuapoGuano1 · « **Reply #56 on:** 02/08/2017 02:22 pm »

Did I miss something? When was 2018 taken off the table for Red Dragon? Is that speculation or confirmed?

BruceM · « **Reply #57 on:** 02/08/2017 02:22 pm »

Have seen no discussion on the disposition of the 3 FH first stages. Guess we can assume one will return to LZ1 and OCISLY will catch another. Presumably the third will travel too far east for recovery this time but can still wonder if JRTI were here... -- Has anyone checked the docks in LA?

Quote from: jpo234 on 02/08/2017 09:46 am

A circumlunar Dragon flight would test FH and Dragon for the Red Dragon mission planned for next year. Everything we know indicates that NASA is excited and not embarrassed about Red Dragon; after all, they provide support.

How cool would it be for SX to refly one or two S1s and the Dragon, recover two S1s (or even three) from the same flight and maybe do something like that circumlunar trip of Dragon followed by recovering it too?

What a great statement for Falcon Heavy, for saying reusability is here and for SX saying we’re now open for business for lunar and Mars exploration as well! Combine all this with a huge audience viewing LC 39A returning to service and remembering that historical time in 1969…

Can hardly sit still thinking about all this! Glad to be sharing this exciting time with everyone!

Herb Schaltegger · « **Reply #58 on:** 02/08/2017 02:31 pm »

Quote from: BruceM on 02/08/2017 02:22 pm

Have seen no discussion on the disposition of the 3 FH first stages. Guess we can assume one will return to LZ1 and OCISLY will catch another. Presumably the third will travel too far east for recovery this time but can still wonder if JRTI were here... -- Has anyone checked the docks in LA?

There's info in other threads about SpaceX's plans to add two additional pads to LZ-1.

old_sellsword · « **Reply #59 on:** 02/08/2017 02:33 pm »

Quote from: BruceM on 02/08/2017 02:22 pm

Have seen no discussion on the disposition of the 3 FH first stages. Guess we can assume one will return to LZ1 and OCISLY will catch another. Presumably the third will travel too far east for recovery this time but can still wonder if JRTI were here... -- Has anyone checked the docks in LA?

The side boosters are identical in every way, they'll be landing in the same location: LZ-1. In case you missed it, there are now concrete plans for expansion there that entails two new landing pads. The original comment is here.

Whether or not the center core can RTLS will be determined by the payload and destination orbit, neither of which are known right now.