[AR] Re: 500,000 tons per year to GEO (off topic)

  • From: Bill Claybaugh <wclaybaugh2@xxxxxxxxxx>
  • To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
  • Date: Wed, 2 Apr 2014 22:29:21 -0700

Henry:

See below:

Sent from my iPhone

On Apr 2, 2014, at 21:30, Henry Vanderbilt <hvanderbilt@xxxxxxxxxxxxxx> wrote:

> On 4/2/2014 12:53 PM, Bill Claybaugh wrote:
>> Please.
>> 
>> Landing the first stage downrange uses 15% of the payload; flying it
>> back up range cost 30% of payload.  Even if refurbishing and relaunch
>> were free, propulsive fly back will take four launches just to cost
>> the same as expending. Since they are not free, it is more likely to
>> take something between 12-24 launches for this system to cost exactly
>> the same as the expendable version.
> 
> Bill - The premises behind your math here are not clear to me.  Could you 
> elaborate a bit?

Take a simple case where reuse "costs" 50% of payload.  Then, if refurbishment 
cost is zero and relaunch costs exactly as much as the expendable version, it 
takes twice as many launches of the reusable version to make the cost of the 
reusable equal to the cost of the expendable version.

Still ignoring refurbishment, if we want the reusable version to price at half 
the price of the expendable version, it follows that it must fly (have an 
economic lifetime of) four times (uses).

If we want it to get to 1/10th the price of the expendable version (say, $250 
per pound) the we need 20 flights.

Now if refurbishment costs are very low--and Falcon 9 is in some ways a highly 
operable vehicle--we might need another 10%; say 22 flights per vehicle.

But if refurbishment is costly (say 50%), then we could be looking at 40 
flights to meet that price goal.

If you redo this for a rocket back first stage, you find that only near zero 
refurbishment can get you $1000 per pound at the five-six mission lifetime that 
the hardware might tolerate. If refurbishment is more costly (as a percentage 
of the cost of a new stage) the economic lifetime for just breaking even with 
the expendable quickly runs up to a dozen flights or more. Then add the risk 
that the hardware is not going to tolerate even five uses.

Finally, it is unlikely that the two kinds of stages have the same launch 
costs; the greater complexity of the reusable stages must impose some 
additional launch processing costs.  Add another 5% for that effect?

>> This also means that production rates will drop and so those cost
>> will go up.
> 
> Leaving aside refurbishment/reuse costs, the cost multiplier for lower 
> first-stage production rates would have to equal the number of stage uses 
> before reuse failed to reduce cost per launch.  IE, if they fly each stage 
> twice, as long as each new stage costs less than double at the reduced 
> production rate, they're still ahead.  Three flights, each stage only has to 
> cost less than triple at reduced production, and so on.

The issue here is that unless labor and plant are cut, overhead costs go up; 
this effects the entire production line, reusable and expendable.  There is 
also a reliability effect, btw.

> 
> Yes, refurbishment/reuse costs can't be ignored.  But lower stage production 
> rates really doesn't look like a show-stopper.
> 
> 
>> And then there's the customers who want to know why they should fly
>> on a used rocket....
> 
> I believe I've seen Elon address this somewhere - the gist was, he 
> understands NASA will probably insist on new stages; other customers will 
> likely be more flexible.  The implication is discounts for used stages.  I'd 
> expect that the first few flights on used F9R's will go for major discounts.  
> Presumably once the actual degree of reliability loss involved is 
> demonstrated, the discount would be adjusted appropriately.
> 

Understood; the question is where the lower cost that allows the discounted 
pricing is coming from: the implied refurbishment cost is near zero unless 
these originally-designed-to-be-expendable stages can somehow tolerate a dozen 
or so flyback missions.

Bill

>> 
>> $100 per pound is not achievable with this system.
> 
> I do tend to agree.  I'd be quite surprised if F9 stages turn out to be 
> reliably reusable without major rework more than a handful of times. Even so, 
> if CSTS wasn't totally wrong about market elasticity, I see a reasonable 
> chance SpaceX can bring their F9 per-lb costs down into the high-to-mid three 
> figures.  Which I would expect will then be revolutionary enough, as that 
> demonstrated growing market makes new investment in further cost reductions 
> sensible rather than visionary.
> 
> Henry
> 
>> 
>> Bill
>> 
>> Sent from my iPhone
>> 
>> On Apr 2, 2014, at 10:49, marsbeyond@xxxxxxxxx wrote:
>> 
>>> Kieth,
>>> 
>>> When is Skylon supposed to fly? In less than two years, SpaceX will
>>> be using propulsive recovery to re-use the first stage, second
>>> stage, and capsule, and their cost to LEO will drop to $100 a
>>> pound!
>>> 
>>> Sent from my iPhone
>>> 
>>> On Apr 2, 2014, at 9:27 AM, Keith Henson <hkeithhenson@xxxxxxxxx>
>>> wrote:
>>> 
>>>> http://theenergycollective.com/keith-henson/362181/dollar-gallon-gasoline
> $350 million committed so far to the Skylon engines.
>>>> 
>>>> Keith
>

Other related posts:

  1. Home
  2. arocket
  3. Archive
  4. 04-2014