Not if in the process SpaceX's costs go below those projected for Skylon.
I'd imagine that Skylon's launch prices would depend strongly on flight rate - probably more strongly than SpaceX's, since the system is fully reusable with a relatively high DDT&E cost and potentially very low processing overhead.
The current projection of $20M per flight is ten times the lowest number they've ever produced, which was for low-value cargo in an arbitrarily large market.There are other advantages as well, such as the Shuttle-like on-orbit ops and downmass capabilities (without adding cost and reducing payload mass and volume by adding a capsule) and the very high projected reliability. It's not really an apples-to-apples comparison, and even if SpaceX comes out cheaper, price may not be the only relevant market factor.
Ummm... Development costs are sunk costs and so have no impact whatsoever on the operational economics.Flight rate is important if you have high (operational) fixed costs like a standing army of engineers for maintenance, support infrastructure that needs to be operated and so on.
There's no reason to actually think Skylon would have better reliability.
historically liquid hydrogen systems haven't been as reliable as systems using other sorts of fuel.
Ummm... Development costs are sunk costs and so have no impact whatsoever on the operational economics.
Concord had excessive operating costs (it was still lossy after they wrote down all of the purchase costs)
Quote from: ChrisWilson68 on 11/03/2015 09:53 pmThere's no reason to actually think Skylon would have better reliability.Sure there is. It's the nature of the vehicle we're talking about, not the bolt supplier's testing practices. You don't get multiple orders of magnitude on your loss-of-vehicle numbers by fiddling with the design details.
Skylon is more of an airplane than a rocket.
It takes off and flies like an airplane, which allows it to have full intact abort capability (including engine out) with no black zones.
It lands like an airplane (well, like a glider), which is a comfortable, well-understood maneuver (particularly for a computer)
and doesn't put a main engine relight on the critical path with no time to troubleshoot if it doesn't work.
It is intended to be certified like an airplane, with an extensive test programme putting two prototypes through hundreds of flights including dozens of abort tests,
and each production unit will undergo four test flights before delivery.
It is also an SSTO, which means that it can wait out bad weather on orbit or divert to almost anywhere in the world (the wings afford a very large cross range),
and that if staging (a major launch risk) is required at all, it can be done at a leisurely pace after the launch, as more of a payload deployment than a controlled inflight breakup.
And of course it's fully reusable, which means infant mortality should be way down.
As of March 2014, REL was targeting a 1% abort rate and a 0.005% loss rate per mission, and based on earlier comments by Mark Hempsell they expect both those metrics to be much better in actual operation.
In other words, those are more like must-not-exceed numbers than optimistic projections.
Quotehistorically liquid hydrogen systems haven't been as reliable as systems using other sorts of fuel.CentaurSaturn VDC-XAriane 5Delta IVSTS...I don't see the problem,
unless you're talking about niggling intermittent launch-delaying issues like the Shuttle's GUCP troubles or the Delta IV's sticky fuel valves, which aren't really the sort of thing I was talking about.
Even those should be greatly mitigated by the extensive flight test programme (so systematic design and maintenance issues can be worked out) and by the highly reusable nature of the whole system (so you don't have untried factory fresh parts on every launch).
Based on what we know of the engine, they seem to have circumvented the main issues with the SSME that made it dangerous and maintenance-intensive.
(Even so, note that Falcon 9 has already had more catastrophic engine failures than STS...)
Quote from: pippin on 11/04/2015 01:49 amUmmm... Development costs are sunk costs and so have no impact whatsoever on the operational economics.They affect launch prices (not costs),
because they affect the purchase price of the vehicles. Skylon doesn't have thousands of years to pay back its development costs; there's a finite horizon within which you have to confine your economic analysis, and the development cost looms large in that context.Even as matters stand, the numbers they're talking about seem pretty competitive. The more SpaceX expands the market, the more likely it becomes that Skylon will undercut them.
The one payload Skylon would be good for is delivering fuel. Especially if they can hit $1000kg mark as per their website. There are no fuel depots at present, but ULA and their distributed launch system offers hope here.
Yeah, Skylon's very high development costs make its economics highly dependent on flight rate.
In terms of downmass, I agree Skylon might have an advantage. It's not clear how much that will count in the market. STS never carried much downmass, though things might change in the future and with much lower costs to orbit.
The "very high projected reliability" part, though, I completely disagree with. There's no reason to actually think Skylon would have better reliability. It's a paper rocket at this point, and no detailed design has been done, so there's little to go on for projecting reliability,
but historically liquid hydrogen systems haven't been as reliable as systems using other sorts of fuel.
I'd imagine that Skylon's launch prices would depend strongly on flight rate - probably more strongly than SpaceX's, since the system is fully reusable with a relatively high DDT&E cost and potentially very low processing overhead. The current projection of $20M per flight is ten times the lowest number they've ever produced, which was for low-value cargo in an arbitrarily large market.There are other advantages as well, such as the Shuttle-like on-orbit ops and downmass capabilities (without adding cost and reducing payload mass and volume by adding a capsule) and the very high projected reliability. It's not really an apples-to-apples comparison, and even if SpaceX comes out cheaper, price may not be the only relevant market factor.
Quote from: 93143 on 11/03/2015 08:30 pmI'd imagine that Skylon's launch prices would depend strongly on flight rate - probably more strongly than SpaceX's, since the system is fully reusable with a relatively high DDT&E cost and potentially very low processing overhead.Yeah, Skylon's very high development costs make its economics highly dependent on flight rate.
Quotehistorically liquid hydrogen systems haven't been as reliable as systems using other sorts of fuel.Centaur ExpendableSaturn V ExpendableDC-X Suborbital experimentAriane 5 ExpendableDelta IV ExpendableSTS Expendable hydrogen tank, very expensive and high-maintenance engine....
Dragon can also wait out bad weather on orbit. It doesn't need much cross-range capability to do that.
In a powered airplane, there's the option to throttle up and go around, and airplanes use that option not too infrequently. Gliders don't have the choice. A Dragon doing a propulsive landing has the choice. If there's a momentary gust of wind, it can throttle up, go up in the air, then settle back down again.