Author Topic: Reusability effect on costs  (Read 168051 times)

Offline OneSpeed

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Re: Reusability effect on costs
« Reply #640 on: 09/17/2017 03:36 AM »
... Let's see how they handle the 26x bigger energy dissipation problem that orbital entry has over booster recovery.

The highest Falcon S1 velocity so far is BulgariaSat-1, which was doing 2389 m/s at the start of its entry burn.
FWIW, here is a table comparing BulgariaSat-1 with some values taken from sims of Falcon S2 EDL from LEO and GTO.

StageMassVelocityEnergyEnergy per mTPeak heatingAltitudeVelocityAcceleration
S1 BulgariaSat-149 mT2,384 m/s139 MJ2.84 MJ116 kW/m^225kms1,656 m/s3.5 g
S2 LEO6 mT7,400 m/s164 MJ27.3 MJ732 kW/m^252 kms6,135 m/s2.2 g
S2 GTO6 mT9,600 m/s276 MJ46 MJ1,836 kW/m^255 kms8,744 m/s3.1 g

From these figures S2-GTO needs to dissipate 46/2.84 = 16.2 times more energy/tonne than BulgariaSat-1.
S2-GTO would have 1,836/116 = 15.8 times more peak heating.

In my sims, I'm assuming S2 doesn't need landing engines, and hence fuel (except for nitrogen). If it did, then both energy to dissipate and peak heating would be a little higher.

Online hkultala

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Re: Reusability effect on costs
« Reply #641 on: 09/17/2017 05:51 AM »
... Let's see how they handle the 26x bigger energy dissipation problem that orbital entry has over booster recovery.

The highest Falcon S1 velocity so far is BulgariaSat-1, which was doing 2389 m/s at the start of its entry burn.
FWIW, here is a table comparing BulgariaSat-1 with some values taken from sims of Falcon S2 EDL from LEO and GTO.

StageMassVelocityEnergyEnergy per mTPeak heatingAltitudeVelocityAcceleration
S1 BulgariaSat-149 mT2,384 m/s139 MJ2.84 MJ116 kW/m^225kms1,656 m/s3.5 g
S2 LEO6 mT7,400 m/s164 MJ27.3 MJ732 kW/m^252 kms6,135 m/s2.2 g
S2 GTO6 mT9,600 m/s276 MJ46 MJ1,836 kW/m^255 kms8,744 m/s3.1 g

From these figures S2-GTO needs to dissipate 46/2.84 = 16.2 times more energy/tonne than BulgariaSat-1.
S2-GTO would have 1,836/116 = 15.8 times more peak heating.


Where are those "peak heating" and "altitude" numbers from/how are they calculated?

Shouldn't S2 GTO be able to aerobrake into LEO before the final re-entry?

Quote
In my sims, I'm assuming S2 doesn't need landing engines, and hence fuel (except for nitrogen). If it did, then both energy to dissipate and peak heating would be a little higher.

No, not "little higher" but "much higher".
Almost half of your 1st stage weight is landing fuel but you totally ignore it for 2nd stage?


Offline OneSpeed

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Re: Reusability effect on costs
« Reply #642 on: 09/17/2017 07:31 AM »
Where are those "peak heating" and "altitude" numbers from/how are they calculated?

The values are taken from sims of Falcon S2 EDL, e.g. https://forum.nasaspaceflight.com/index.php?topic=42389.msg1723803#msg1723803

Shouldn't S2 GTO be able to aerobrake into LEO before the final re-entry?

It should. It would be interesting to see how much it would reduce the size of the energy dissipation requirement.

In my sims, I'm assuming S2 doesn't need landing engines, and hence fuel (except for nitrogen). If it did, then both energy to dissipate and peak heating would be a little higher.

No, not "little higher" but "much higher".
Almost half of your 1st stage weight is landing fuel but you totally ignore it for 2nd stage?

Because the re-useable S2 would be configured for side entry, it could slow to a much lower velocity than S1 just using aerodynamic drag and lift. It would not need retro-propulsive or entry burns. By the time it came to perform a landing burn, the fuel (and thrust) requirement would be much less than half S2 mass.

Offline john smith 19

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Re: Reusability effect on costs
« Reply #643 on: 09/17/2017 12:22 PM »
Wingless reentry vehicle designs exist, including quite large and long ones. Slosh baffles exist. Pressurized tanks are rigid. Payload bay with doors will be a little heavier than F9's carbon composite inter-stage. Windward TPS will weigh no more than 10 kg/m^2. SuperDracos exist for landing. Lots of work, but nothing way out. I have attached a Russian reusable vehicle similar in shape to what we might expect for a reusable S2. This is not that different from BFS.
What you're missing is you have to have all of these things together, and you're grossly underestimating any kind of payload bay mass. The Shuttle payload bay was not a pressure stabilized design so the doors (or their frames) had to be load carrying.

All of these features multiply together to make the problem very much harder. You're trying to cram the requirements of an orbiter into the payload fraction of a stage and wishing something will turn up.

As for the Russian concept. I learned a long time ago that in CAD anything is possible.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C Apply So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline john smith 19

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Re: Reusability effect on costs
« Reply #644 on: 09/17/2017 12:23 PM »
In my sims, I'm assuming S2 doesn't need landing engines, and hence fuel (except for nitrogen). If it did, then both energy to dissipate and peak heating would be a little higher.
So how does it land?
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C Apply So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline OneSpeed

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Re: Reusability effect on costs
« Reply #645 on: 09/17/2017 12:44 PM »
In my sims, I'm assuming S2 doesn't need landing engines, and hence fuel (except for nitrogen). If it did, then both energy to dissipate and peak heating would be a little higher.
So how does it land?

If it does not require landing engines or fuel, the terminal velocity of the reusable Falcon S2 would be very low, around 50m/s. At those speeds, a drogue chute / parafoil combination begins to look feasible. I've modelled it at https://forum.nasaspaceflight.com/index.php?topic=42389.msg1723803#msg1723803

Offline livingjw

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Re: Reusability effect on costs
« Reply #646 on: 09/17/2017 07:13 PM »
Wingless reentry vehicle designs exist, including quite large and long ones. Slosh baffles exist. Pressurized tanks are rigid. Payload bay with doors will be a little heavier than F9's carbon composite inter-stage. Windward TPS will weigh no more than 10 kg/m^2. SuperDracos exist for landing. Lots of work, but nothing way out. I have attached a Russian reusable vehicle similar in shape to what we might expect for a reusable S2. This is not that different from BFS.
What you're missing is you have to have all of these things together, and you're grossly underestimating any kind of payload bay mass. The Shuttle payload bay was not a pressure stabilized design so the doors (or their frames) had to be load carrying.

All of these features multiply together to make the problem very much harder. You're trying to cram the requirements of an orbiter into the payload fraction of a stage and wishing something will turn up.

As for the Russian concept. I learned a long time ago that in CAD anything is possible.

I am not saying that there wouldn't be a very large payload hit, there will be. Pessimistically, remaining payload capacity may be as low as 5000 kg to ISS. I understand that the payload bay and doors need to be load carrying similar to an inter-stage but worse. On top of this you need either parachutes, or landing propellant. Ballistic Coefficient will be somewhere around 150- 160 kg/m^2 (30-33 lb/ft^2). I think a good way of thinking about the problem is to start by thinking how you would integrate a Dragon 2 with its second stage into a single recoverable vehicle. It would be about 26 M long.

John

Offline john smith 19

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Re: Reusability effect on costs
« Reply #647 on: 09/23/2017 07:18 AM »
I am not saying that there wouldn't be a very large payload hit, there will be. Pessimistically, remaining payload capacity may be as low as 5000 kg to ISS.
And you got that number how exactly?
Quote from: livingjw
I understand that the payload bay and doors need to be load carrying similar to an inter-stage but worse.
I don't think you do. Shuttle weighed around 200Kb to carry 65Klb to orbit. It never achieved that and managed about 55Klb. IOW it was 72.5% structure. the S2 is is more in the 3-5% range.
Quote from: livingjw
On top of this you need either parachutes, or landing propellant. Ballistic Coefficient will be somewhere around 150- 160 kg/m^2 (30-33 lb/ft^2).
Derived how?
Quote from: livingjw
I think a good way of thinking about the problem is to start by thinking how you would integrate a Dragon 2 with its second stage into a single recoverable vehicle. It would be about 26 M long.
I'll leave others to decide if they agree with that plan.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C Apply So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline calapine

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Re: Reusability effect on costs
« Reply #648 on: 10/12/2017 12:40 PM »
I hope this is the right thread for this:

SpaceX reassures commercial satellite market: Falcon 9 won’t soon be scrapped for BFR

Peter B. de Selding reports the remarks by SpaceX Sr. Director Tom Ochinero. Some key points are:

  • Falcon 9 is here to stay longer Quote:
  • Quote
    "I can see how people might take it that we are going to shut down and transfer. This is not the case. We’ll continue to produce Falcon, then develop BFR and then offer it to the market and see what the market chooses."

  • Discount for Falcon 9 with re-used first stage will be phased out
  • Currently there is no need for the Texas launch sites.
  • Falcon Heavy is still planned and fly this year.
  • « Last Edit: 10/12/2017 12:41 PM by calapine »

    Offline RedLineTrain

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    Re: Reusability effect on costs
    « Reply #649 on: 10/12/2017 02:42 PM »
    @calapine --  Most relevant for this thread, insurance rates for reused boosters aren't higher than new boosters.
    « Last Edit: 10/12/2017 02:42 PM by RedLineTrain »

    Offline john smith 19

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    Re: Reusability effect on costs
    « Reply #650 on: 10/12/2017 03:25 PM »
    I hope this is the right thread for this:

    SpaceX reassures commercial satellite market: Falcon 9 won’t soon be scrapped for BFR

    Peter B. de Selding reports the remarks by SpaceX Sr. Director Tom Ochinero. Some key points are:

    Quote
    Discount for Falcon 9 with re-used first stage will be phased out

    This thread's title is not very helpful.

    The "cost" to SX is unknown. The development budget is stated to be circa $1Bn

    What matters is the "cost" to customers for access to space.

    Or price as most people call it.

    And the answer to the difference reusability is going to make to price is now clear.

    Nothing

    If you could get into orbit at 10s of $m price you still can.

    If you can't. You still can't.  :(

    This was always one of the options of pricing reusable stages. The even worse option would be they started charging a premium for pre-flown boosters as they were known to work.

    "Profit" may not be Musks ultimate goal but development cost recovery ASAP certainly does.

    But not to worry $5m a launch will be here when BFS finally starts flying.

    Right?
    « Last Edit: 10/12/2017 03:28 PM by john smith 19 »
    BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C Apply So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

    Online envy887

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    Re: Reusability effect on costs
    « Reply #651 on: 10/12/2017 03:38 PM »
    I hope this is the right thread for this:

    SpaceX reassures commercial satellite market: Falcon 9 won’t soon be scrapped for BFR

    Peter B. de Selding reports the remarks by SpaceX Sr. Director Tom Ochinero. Some key points are:

    Quote
    Discount for Falcon 9 with re-used first stage will be phased out

    This thread's title is not very helpful.

    The "cost" to SX is unknown. The development budget is stated to be circa $1Bn

    What matters is the "cost" to customers for access to space.

    Or price as most people call it.

    And the answer to the difference reusability is going to make to price is now clear.

    Nothing

    If you could get into orbit at 10s of $m price you still can.

    If you can't. You still can't.  :(

    This was always one of the options of pricing reusable stages. The even worse option would be they started charging a premium for pre-flown boosters as they were known to work.

    "Profit" may not be Musks ultimate goal but development cost recovery ASAP certainly does.

    But not to worry $5m a launch will be here when BFS finally starts flying.

    Right?

    SpaceX can't launch fast enough right now to satisfy existing demand. SES stated that they are going with used boosted because SpaceX can fly them sooner... which is a different kind of value. Even with a used booster they can't fly till January. Upper stage production, pad availability, payload processing, vehicle testing, etc are limiting.

    Maybe at 30 launches per year they will have some slack. Or it might take 50, if they start launching for Starlink.

    But don't expect to see the price go down any more until supply catches up with demand. Econ 101.

    Offline meberbs

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    Re: Reusability effect on costs
    « Reply #652 on: 10/12/2017 03:39 PM »
    I hope this is the right thread for this:

    SpaceX reassures commercial satellite market: Falcon 9 won’t soon be scrapped for BFR

    Peter B. de Selding reports the remarks by SpaceX Sr. Director Tom Ochinero. Some key points are:

  • Falcon 9 is here to stay longer Quote:
  • Quote
    "I can see how people might take it that we are going to shut down and transfer. This is not the case. We’ll continue to produce Falcon, then develop BFR and then offer it to the market and see what the market chooses."

  • Discount for Falcon 9 with re-used first stage will be phased out
  • Currently there is no need for the Texas launch sites.
  • Falcon Heavy is still planned and fly this year.
  • The previous statements are key context for that quote, and indicate that they know that what the market will choose is obvious. He had repeated about there being a "stable" of F9 rockets by then. What he says doesn't conflict with anything Musk said at IAC, but clarifies it. Rather than shut down F9 production while BFR is in development and cross their fingers that nothing goes wrong, they will wait until BFR is flying and they are not getting more F9 orders so they can be certain that their stockpile is large enough to cover the remaining F9 contracts.

    He also reiterated the roughly $1 billion figure for reusability development, and stated that they won't try to get it all back with Falcon 9 since that would take 10 years or more. At a rate of 30 launches per year, this means a net of $3 million per flight. This means that average reusability cost reduction would be about $3 million more than what they pass on to customers. Tons of assumptions in this though.

    He also mentions that "the economics are not quite that simple." I am guessing that refers to the fact that any increase in contracts won due to lower prices would have to be factored in, plus internal launches for the constellation will have interesting accounting. Also as I see it, the $1 billion is a sunk cost at this point, so it doesn't truly matter, and in an analysis of "was it worth it" you have to account for the fact that it got them the experience they need to design BFR, so in some difficult to account for way BFR can pay this off.

    "Profit" may not be Musks ultimate goal but development cost recovery ASAP certainly does.
    You clearly didn't actually read the link (it is not that long) since the part I referenced above directly contradicts this.

    Also, the price difference will not be 0, he said the difference in price between new and reused will go away, this does not mean that they will charge current new prices for everything, just the same price for everything. And the rough analysis I did above indicates we can know something about costs.

    Offline yokem55

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    Re: Reusability effect on costs
    « Reply #653 on: 10/12/2017 03:51 PM »
    What it comes to is that the money spent on reusability development was money from selling equity in the company and not bonds that have a fixed repayment schedule. The way you 'pay back' equity investors is to increase the value of what they own by increasing the value of the company. They are doing exactly that. They have a solid (knock on wood) product that is attracting a large manifest of customers that they can profitably serve, and thus use those profits to fund other R&D ventures that will likely be more profitable. Unless the equity holders start begging for dividends (and until Musk has less than a 50% stake in the company there won't be any) those profits will be rolled into making the company more valuable.

    Online envy887

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    Re: Reusability effect on costs
    « Reply #654 on: 10/12/2017 08:14 PM »
    I hope this is the right thread for this:

    SpaceX reassures commercial satellite market: Falcon 9 won’t soon be scrapped for BFR

    Peter B. de Selding reports the remarks by SpaceX Sr. Director Tom Ochinero. Some key points are:

    Discount for Falcon 9 with re-used first stage will be phased out
    So no discount.  If SpaceX had not spent the $1 billion for reuse development, it could be charging less, flying smaller rockets to get the same capability, etc.?

     - Ed Kyle

    Perhaps. Perhaps not.

    But they would certainly not be closer to a vehicle than can get affordably anyone Mars.

    Offline Cherokee43v6

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    Re: Reusability effect on costs
    « Reply #655 on: 10/12/2017 08:18 PM »
    Actually, it sounds more like they feel like they have now proven that 'flight proven' boosters are as reliable as new builds, thus the 'first adopter encouragement' discounts are being discontinued.  Kinda like the government phasing out tax breaks on electric cars after a certain volume is achieved.

    The discounts were not structured to say reuse is cheaper... they were done to convince a skeptical customer base to accept the reflight risk.  Reuse is still new enough that proving savings is not yet possible as they are still learning what they have to do and what they don't have to do when refurbishing for the next flight.

    First you prove reflight. Then you streamline the processes to achieve the savings.  Then you evaluate to see if you gain, lose or break even.
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            ...I just pointed at it and laughed a little too loudly."

    Offline CuddlyRocket

    Re: Reusability effect on costs
    « Reply #656 on: 10/12/2017 08:26 PM »
    So no discount.  If SpaceX had not spent the $1 billion for reuse development, it could be charging less, flying smaller rockets to get the same capability, etc.?

    Yes, but with nowhere to go from there. Reusability enables the future.

    Offline RedLineTrain

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    Re: Reusability effect on costs
    « Reply #657 on: 10/12/2017 08:29 PM »
    So no discount.  If SpaceX had not spent the $1 billion for reuse development, it could be charging less, flying smaller rockets to get the same capability, etc.?

    A couple of possible implications:  (1) SpaceX will charge less for both the reuse and non-reuse payloads on new contracts; and (2) SpaceX will disallow the non-reuse payloads on new contracts.
    « Last Edit: 10/12/2017 08:30 PM by RedLineTrain »

    Offline rockets4life97

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    Re: Reusability effect on costs
    « Reply #658 on: 10/12/2017 08:40 PM »
    The issue now is SpaceX is spending heavily on BFR and Starlink. They need all the profit they can get in the near term. These priorities are higher then their desire to reduce the cost of launch (although BFR promises to do that indirectly) -- which must be noted in an altruistic goal. Most every other company operates on profit maximization.

    Reusability should lower costs for SpaceX, but prices will probably remain stable until they face increased competition. I could also see there being a lower price tier in the future for science payloads, while keeping the commercial satellite price stable.

    Offline yokem55

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    Re: Reusability effect on costs
    « Reply #659 on: 10/12/2017 08:47 PM »


    I hope this is the right thread for this:

    SpaceX reassures commercial satellite market: Falcon 9 won’t soon be scrapped for BFR

    Peter B. de Selding reports the remarks by SpaceX Sr. Director Tom Ochinero. Some key points are:

    Discount for Falcon 9 with re-used first stage will be phased out
    So no discount.  If SpaceX had not spent the $1 billion for reuse development, it could be charging less, flying smaller rockets to get the same capability, etc.?

     - Ed Kyle

    They still would have needed the 1.1 upgrade to complete the CRS contract. The 1.2 performance upgrades were needed for the larger GTO contracts unless they were faster about developing FH. In the meantime they've cut their manufacturing costs with production improvements (some of Merlin is printed, bolted octoweb, etc.)

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