[AR] Re: Reusable Dragon & Grasshopper delta V (off topic)
- From: Norman Yarvin <yarvin@xxxxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Fri, 1 Aug 2014 12:22:59 -0400
Well, that's the nature of online discussions: one person makes a
statement, and another says to himself "wait, is that really true in
general... no, there can be cases where it doesn't apply", and then
says so.
It especially tends to happen if you have people with a taste for
theory in the discussion, since theorists (at least good ones) know
that if you don't keep theory rigorous, it quickly degenerates into
the useless morass that many practical people take it for. Insisting
on rigor is not just trying to be offensive, though it often comes off
that way.
On Fri, Aug 01, 2014 at 09:55:15AM -0400, Bill Claybaugh wrote:
>Norman:
>
>If this is the concern; I am baffled: it seems--to me--too abstract,
>too theoretical, too picayune. Excepting the two years for transition
>between systems this "problem" is unlikely to ever exist.
>
>Bill
>
>Sent from my iPhone
>
>On Aug 1, 2014, at 7:37, Norman Yarvin <yarvin@xxxxxxxxxxxx> wrote:
>
>> On Thu, Jul 31, 2014 at 08:46:10PM -0400, Bill Claybaugh wrote:
>>
>>> I'm still not certain I understand the question, but let us assume
>>> that there exist an ELV that will place 30,000 pounds in LEO for $2000
>>> per pound (= $60 million); let us call this vehicle "100%".
>>>
>>> Now let us further assume that there exists a derivative of "100%"
>>> that has a boost back first stage with near zero refurbishment costs;
>>> further assume that this vehicle--per previous estimate--is capable of
>>> six first stage flights and accordingly is priced at $1000 per pound
>>> for 30% less payload. Call this vehicle "70%".
>>>
>>> 21,000 pounds at $1000 per pound is $21 million vs 30,000 pounds for
>>> $60 million, no? Whether we calculate in price per launch or in price
>>> per pound the result is the same: no rational economic actor buys the
>>> ELV for LEO missions; the project cost will--up to a calculable
>>> limit-- be lower if one spends more on making the spacecraft fit the
>>> 21k pound vehicle.
>>
>> Well, except for the people to whom a 30,000 pound satellite is worth
>> more than $39 million more than a 21,000 pound satellite, due to its
>> higher capability. I'm not sure who those people might be; either
>> figure is quite a substantial satellite, even if most of that mass
>> would be used to raise the orbit from LEO to GEO. But that was (if I
>> understood it) Henry's point, in an abstract sense. For the Falcon 9
>> (those figures being close to the Falcon 9's) the argument might not
>> make much practical difference, but a smaller launcher might see much
>> of its market disappear if it started cutting payload.
>>
>>
>> --
>> Norman Yarvin http://yarchive.net/blog
>>
>
Other related posts: