Ashley Dove-Jay, PhD researcher in Aerospace Engineering, University of Bristol, analyzed the launch costs of fully reusable Spacex rockets against the also in development Skylon spaceplanes.
UPDATE : There is an update on the Falcon 9 Block 5 rocket which should have a 24 hour turnaround with no refurbishment resue and will be reusable about a dozen times.
Ashley used a reference document from Reaction Engines. The document is no longer available online.
Skylon remains uncompetitive when compared with even the partially reusable (let alone the fully reusable) Falcon rockets:
* Skylon costs about 30 times more than a Falcon 9 and 20 times more than a Falcon Heavy. While it is hypothetically more reliable (though I question this), such an enormous difference has a significant impact on insurance costs, which drives up operating costs further.
* Using an exotic and relatively expensive combination of jet and rocket propellants, it costs about six times more to refuel Skylon than a Falcon 9, and twice as much as a Falcon Heavy.
Skylon still needs a decade of development and testing – and £14 billion in investment.
Reaction Engines is gaining the support of the US Air Force.
Reaction Engines could be a way to achieve hypersonic fighter jets and spyplanes.
Even here though, low cost access to space could enable networks of low earth orbit satellites to have constant high resolution observation of the Earth by the early to mid-2020s.
Stratospheric balloons (Google Loon) and drones will also enable close up and high resolution observation of the Earth.
The main application then for Reaction Engines would be billion dollar a piece hypersonic fighter jets.
Perhaps later generation hypersonic planes would not be as costly and could be made reliable and low cost enough for hypersonic commercial passenger jets.
Spacex reusable rockets and any reusable spaceplanes need high volume applications like launching tourist passengers
Elon Musk is trying to make hundreds of flights per year economic by launching and maintaining a network of 4000-20,000 internet satellites.
There were 92 space launches worldwide in 2014.
Supporting a global network of 20,000 or more internet satellites (with 10-30 in each launch) would end up being a few hundred flights per year to space on a sustained maintenance basis and one to two thousand during the main deployment phase.
Full reusability of all stages could be technically proven in two years and a standard part of Spacex launches within five years.
By 2022, the buildout of the internet satellite network should be in full swing and the cost to low earth orbit per person (1000-2000 pounds to orbit, not the full rocket payload) could drop to $200,000 to $400,000 based upon the following chart of costs and launch frequency.
The truly lower costs from reusable vehicles are only fully realized from a high number of reuses and high number of flights per year. You can think of how costly a commercial jet would be if it only could fly a few times per year.
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1 thought on “Fully reusable Spacex Rockets would be lower cost than Skylon spaceplanes”
Nice charts, but leave a lot of questions. Skylon take-off weight is 325t. Why is refueling so much more expensive than Falcon 9 with a take-off mass of 506t? If it is just a matter of RP1 vs LH2, what´s the rationale behind that expensive choice for Skylon? The topic of falcon full reusability seems to be “highly assuming”. IIRC, reusability currently is estimated as a 1/3rd cost reduction, not the 2/3rd of the charts shown here. Compare according adjusted figures for Falcon with the equally “optimistic” figure for Skylon, and Skylon actually shows more competitive vs Falcon 9.
The key difference seems to be the refuel cost issue. Any lights on the issue of relying on fossil fuel in RP1 and why LH2 is so expensive? On maintenance cost, I doubt that there are any available real figures, so everything related to that can only be speculative.
All these assumptions do not yet factor in Musk´s bold promise of the BFR being even more stupendiously cheaper. However, for me it is a mystery how a rocket, which by default needs much more fuel than a spaceplane, which uses environmental air to safe fuel for the first 1/3rd of its ascend through the atmosphere (28km), should be cheaper on a full resuability cycle.
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