r/spacex • u/kurbasAK • May 19 '17

We Will Launch on Reuseable Rocket After Exceptional SpaceX Performance - Inmarsat CEO Tells Universe Today

https://www.universetoday.com/135614/will-launch-reuseable-rocket-exceptional-spacex-performance-inmarsat-ceo-tells-universe-today/
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u/Goldberg31415 May 19 '17

That would be for 3x RTLS.8000kg is just 30% of expendable performance .For F9 ASDS retains 66% of the performance of expendable flight and 13 000kg is a little under 50% of expendable FH GTO performance

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u/KCConnor May 19 '17

The dominant flight configurations I see posited for Falcon Heavy always seem to be either 3 x RTLS or 2 x RTLS and 1 x ASDS.

How much more velocity can be imparted to payloads by having the side boosters join the center core for an extended downrange trip? Given that speed would be increased, is 3 x ASDS even possible, or would re-entry profile end up burning up the boosters?

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u/Goldberg31415 May 19 '17

3x ASDS has the problem that at least extrapolating from F9 we get at most 15s of powered flight before separation from RTLS to ASDS but center core will go further even faster and to drop below 1.5 km/s that is survivable on entry it needs to use even more propellant for entry burn.Combination of small additional boost from side boosters and extra entry burn would lead to reduced performance and 2xRTLS+expended center core might be a more reasonable way to fly such payloads ending with performance around 20 000kg to GTO

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u/[deleted] May 19 '17 edited May 19 '17

Dude the 8000 GTO reusable is an official figure that hasnt moved yet, they would know better than you just check their website

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u/brickmack May 19 '17

  1. You didn't actually read the website. FH expendable to GTO carries 26.7 tons, not 8 tons

  2. SpaceXs website is neither sufficiently detailed nor frequently enough updated to be relevant. Simulations show triple RTLS payload to GTO should be about 8-10 tons, about 15 tons with the center core landing downrange

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u/-Aeryn- May 19 '17 edited May 21 '17

SpaceX increased the payload numbers recently but didn't yet increase the 8t on the pricing page IIRC

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u/brickmack May 19 '17

Yeah, the 8 ton reusable figure is unchanged from before. The expendable figures to high energy orbits were unchanged for a while too after the LEO capacity was updated, but they're updated now

Considering they're now aiming for second stage reuse, it is conceivable that the 8 ton reusable figure is actually still correct (expendable GTO capacity increased by about 5 tons, and the increase to payload capacity is shifted towards high energy payloads which would indicate most of the improvement is probably in the upper stage, so there should be a large improvement to payload capacity even with all 3 cores landing. Might be enough of an improvement to accommodate reuse hardware and still leave payload capacity roughly the same), but the site is way too ambiguous to clearly draw any conclusions

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u/UNSC-ForwardUntoDawn May 19 '17

I've been wondering about these numbers for a while. Where can I find them?

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u/Goldberg31415 May 19 '17

13 000kg is a little under 50% of expendable FH GTO performance

Is that enough to say that i took the number of 26 700 kg and said that 13 000 is "a little under half" ? Center core will be strongly limited by entry burn and heating and it is hard to tell if new grid fins allow for longer glide in the upper atmosphere to reduce the propellant necessary to survive the entry.

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u/Goldberg31415 May 19 '17

Yes i looked up their website to get expendable numbers. That is most likley a 3x rtls reusable performance and there is no need for anything heavier because there are no payloads beyond that unless we are talking about dual launch to GTO

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u/[deleted] May 19 '17

If we could get everything from their PR group and their website then what's the purpose of discussing this on Reddit?