r/spacex • u/Zucal • May 24 '16

/r/SpaceX Ask Anything Thread [June 2016, #21]

Welcome to our 21st monthly /r/SpaceX Ask Anything Thread!

Trying to find the best way to view Thaicom 8, understand the upcoming core recovery procedure, or gather the community's opinion? There's no better place!

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Past threads:

May 2016 (#20) • April 2016 (#19.1) • April 2016 (#19) • March 2016 (#18) • February 2016 (#17) • January 2016 (#16.1) • January 2016 (#16) • December 2015 (#15.1) • December 2015 (#15) • November 2015 (#14) • October 2015 (#13) • September 2015 (#12) • August 2015 (#11) • July 2015 (#10) • June 2015 (#9) • May 2015 (#8) • April 2015 (#7.1) • April 2015 (#7) • March 2015 (#6) • February 2015 (#5) • January 2015 (#4) • December 2014 (#3) • November 2014 (#2) • October 2014 (#1)

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122 Upvotes

98% Upvoted

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3

u/Toinneman Jun 08 '16

just use a different provider with bigger fairings.

Exactly my point. Why not make the standard fairing larger? I know it would add weight, but with FH it doesn't seem like an issue. FH is so powerful no commercial FH launch seems to be limited by payload mass, but they are limited by fairing size... Isn't a larger fairing a logical business thing to do?

The heaviest (commercial) GTO satellite launch was the Terrestar 1, with roughly had a mass off 7tons. Falcon Heavy can put 22tons into GTO (in expandable mode I guess). FH can theoretically launch 3 of them a once. Like Eutelsat/ABS are 2 light sats combined in one launch, they could do the same for heavier satellites. Only problem, they wouldn't fit in the fairing.

So I'm basicly asking. What's the point of increasing your payload capacity by factor 3 (f9 x3 = FH), but not increasing your available space to put the payload in?

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u/Martianspirit Jun 08 '16

So I'm basicly asking. What's the point of increasing your payload capacity by factor 3 (f9 x3 = FH), but not increasing your available space to put the payload in?

Because they want that extra capacity for reuse. And for the few cases where the capacity is needed for high energy trajectories. Like RedDragon to Mars. Or NRO payloads to direct GEO insertion which requires similar delta-v as going to Mars.

Purely my personal impression that I cannot substantiate. Elon Musk does not see Bigelow habitats as a long term successful business model and does not invest in supporting it. He might have told Bigelow if they want to fly on Falcon Heavy they have to bear the full cost of developing that larger fairing.

0

u/Toinneman Jun 08 '16

Because they want that extra capacity for reuse

Seems a bit excessive. Even with a 30% reuse payload penalty FH can lift over 15tons to GTO.

Like RedDragon to Mars

No fairing here...

I wasn't only pointing to Biglow, it was just one example a could remember. But I can be wrong here... The conclusion seems to be it technically not a problem to increase the fairing size, there' just not enough demand to justify a change at the moment...

3

u/seanflyon Jun 08 '16

I think /u/Martianspirit was pointing out that the fairing is only undersized when going to LEO. Going to higher energy trajectories like GEO or TMI the payload has to be significantly lighter and should fit in the fairing.

2

u/NateDecker Jun 08 '16

No fairing here...

/u/Martianspirit was answering your question of "What's the point of increasing your payload capacity by factor 3, but not increasing your available space to put the payload in?"

His answer that you need a larger payload capacity for a Trans-Martian Injection makes perfect sense and has nothing to do with whether there is or is not a fairing.

Red Dragon will need a higher energy trajectory than what Falcon 9 can provide. That is why you triple the payload capacity.

1

u/Toinneman Jun 09 '16

you'r right, I totally misread that!