[AR] Re: fatigue life (was Re: Re: SpaceX F9 Launch/Update...)
- From: Edward Wright <edward.v.wright@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Sat, 9 Jan 2016 14:39:01 -0600
The details matter: RLV's cost more per unit than similar ELV's,
That is a common assumption, but where is there data to support it?
General Dynamics did a study in the 1960's comparing reusable and expendable
vehicles of similar performance (Atlas A and the X-15). They came to the
conclusion that the reusable vehicle cost about 60% as much to develop. The Air
Force did a parallel study at the same time, using different methods, and came
to the same conclusion.
One can argue that orbital RLVs are different, but that's an argument, not
data. You can look at the estimates of RLV development costs, but those are
only estimates based, more likely than not, on the *assumption* that RLVs are
more expensive. It's impossible to do a like-to-like comparison of real data
because no one has built an fully reusable orbital vehicle.
Max Hunter used to say that people who believe RLVs are more expensive forget
that to build a rocket, you need to fly a rocket. A rocket that is cheaper to
fly operationally will also be cheaper to flight test. Anyone who believes RLVs
are more expensive must show other expenses to offset those savings.
ELV testing costs also tend to be understated because ELV developers skimp on
flight tests and push a large portion of the cost/risk to early customers. An
ELV might fly "operationally" for years, even decades, to reach the
demonstrated reliability that an RLV might achieve during the development
flight-test program.
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