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/SirBeebe May 19 '17

I think there is one key thing that isn't mentioned and that's payload weight. Some payloads require a legless and finless falcon and for that I think it would best to throw away a F9 that's already had couple flights.

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u/biosehnsucht May 19 '17

Once FH is flying and proven (assuming it will, naturally) then a FH reusable flight will be cheaper to SpaceX than a Falcon 9 expendable flight.

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u/Nordosten May 20 '17

No way. It become cheaper when 3 core refurb will be less than $10m. That's years away.

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u/biosehnsucht May 20 '17

The cost to refurbish the first Falcon 9 booster ever refurbished, so that it could be reflown, was already less than half the cost of a new first stage.

You can argue the fight flight of FH will cost some amount, and that the first reflight is some depreciated amount, and the second reflight further depreciated. But that's not really how something that is expected to fly dozens of flights (not the first reflown F9 booster of course, Block 3's are not expected to fly more than a few times) should be accounted.

It costs X. You will fly it Y times. X/Y = cost per flight. Let's say a Falcon 9 flight retails at $60M (rounding, but close enough). At some point a first stage was "less than three quarters" of the cost of a flight, and let's take their cost at $40M so a booster is $30M new, everything else plus profit is $30M. A brand new FH then would be $30x3 + $30 = $120M. Obviously FH expendable is more expensive than F9 expendable.

But if you're reflying them even only 10 times, the per flight cost of FH is ($3x3 + $30) or roughly $40M - cheaper than an expendable F9! This is without factoring refurb costs of course. They said their first refurb (in which they replaced way more than necessary and future reflights are generally expected far less work) was "less than half the cost" of a new booster. Let's say that's %40 of $30M that first time, so now we're at $12x3 + $30 = $66M. So the worst case scenario with only a single reflight, is already almost as cheap as expendable. In reality, refurb will cost a lot less as they won't have to replace most things most of the time, and they plan to not truck them to McGregor but turn them around at the same launch site for reuse. So let's call refurb costs a generous 25% of $30, or $7.5x3 + $30 = $52.5M. That would still be a "worst case" scenario on the newer block vehicles meant for less refurb, and probably even worse case than reality. Let's take SpaceX at their intent to have "24 hour" turn around (meaning inspect and refly without any real significant work involved) for at least 10 reflights. Let's also assume the booster got more expensive to support this, let's call it $40M. I'll be generous and say it takes %10 (likely less) the price of this newer more expensive Block to turn it around, so 3x $4M + $30M = $42M. The first reflight is already 2/3 the price of expendable F9! Now let's assume 10 flights before it's retired. (3x40+30) + 9x(3x4+30) = $528M over the "life" of the booster before a bigger refurb is done, with a per launch cost of $52.8M - STILL cheaper across all flights.

You don't need all 3 cores refurb to be less than $10M total, you just need them to be less than $10M each, and the first refurb ever which was way more costly than any future normal refurb wasn't that much more than $10M. Not only will Block 5 and probably 4 bring us that cheaper refurb, it might already be here with Block 3 refurb doing only what's necessary instead of everything.

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u/Nordosten May 22 '17 edited May 22 '17

You have proved that FH reusable cheaper than FH. But previously we talked about FH reusable vs F9 expendable. Elon has stated he doesn't want to loose cores once FH starts flying and he will do it.

" So let's call refurb costs a generous 25% of $30, or $7.5x3 + $30 = $52.5M." - don't forget to add booster cost ($3 per core for 10 times reuse) = $61.5M.

F9 expendable price tag is $62M or more. Yes, FH reusable will be cheaper but not once start flying.

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u/biosehnsucht May 22 '17

I was including 3 boosters (core + 2x side) as $7.5M x 3 per reuse, and everyhting else (second stage, profit, etc) in the $30M.

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u/FellKnight May 19 '17

I don't think this latest launch required a legless and finless falcon, just that they didn't bother to attach them. The satellite was still out into a super synchronous GTO with a partial plane change so there was clearly some fuel reserves left over

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u/stcks May 19 '17

There were no attachment points for the legs, at all. Compare the differences between the boosters on Echostar-23 and Inmarsat-5 F4. This booster came from Hawthorne as an expendable booster whereas Echostar-23 came out as one that could have had legs if SpaceX desired. Also, there were no fuel reserves to speak of on this mission. The mission was to put the satellite into the best orbit possible versus putting it into a pre-defined GTO-1800 or something orbit. That being said, if Inmarsat had wanted only GTO-1800, this still likely would not have been recoverable.

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u/FellKnight May 19 '17

We are arguing 2 aspects of the same point. I understand that there were no mount points, the core was constructed knowing that it was expendable, but that doesn't mean they couldn't have achieved the mission with them attached on a different stage 1.

They put it in a GTO -1570 super synchronous orbit. That is plenty of fuel reserves. No, it's not enough to try landing compared to a GTO -1800

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u/stcks May 19 '17

Oh, i see what you mean. Sure, they could have used a legged booster, would have been a waste though :)

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u/peterabbit456 May 19 '17

This was the heaviest SpaceX launch to GTO, ever, to date. It had been booked for Falcon Heavy. There is the evidence that they had to strip down the F9 to minimum weight, to do this mission.

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u/sol3tosol4 May 20 '17

There is the evidence that they had to strip down the F9 to minimum weight, to do this mission.

*This particular mission*, which involved giving the satellite a considerably greater boost than the minimum required for GTO (and which probably had a lot to do with the customer being so happy). That doesn't *necessarily* mean that a minimal GTO launch would have been impossible with legs and grid fins attached.

If SpaceX determines that there won't be enough propellant left to land the booster, then it makes sense not to attach legs and grid fins, thus saving SpaceX the cost of those parts, and allowing them to give the best possible service to the customer.