Shackleton Energy Company Launches Plan for First Lunar Mining Operation

[Robotbeat]

And, of course, Skylon is probably the spendiest of the RLV proposals out there. It's already operating on razor-thin technical margins to get anything to LEO at all (i.e. there's a pretty big performance difference between pure equatorial and 28 degrees). I think it's the only SSTO RLV out there being actively given any funding. The rest use more than one stage (usually two). It's most certainly NOT the only thing out there, most certainly is the most expensive (development costs) RLV proposal being funded to any extent right now, and IMO doesn't beat the other RLV proposals being funded on cost per kg to LEO.

[93143]

And, of course, Skylon is probably the spendiest of the RLV proposals out there.

That might be because it's the most realistic.  London Economics reviewed their business plan, and the ESA reviewed their technical plan (the old one, not the one with the improved SABRE 4), and neither found any problems.  The only issue is that they haven't demonstrated their heat exchanger tech in an actual engine yet - so yes, it could still fail for technical reasons, but it's not likely.

SpaceX doesn't even know if what they want to do is possible, and they have no idea what it will weigh if it is.  Their cost projections are just spitballing at this point.

A while back, Skylon was estimated to cost as little as $2M per flight for very high flight rates, but that number isn't used to make a business case and you don't hear about it much (it's still in the FAQ, but who reads those?).

It's already operating on razor-thin technical margins to get anything to LEO at all (i.e. there's a pretty big performance difference between pure equatorial and 28 degrees).

Not so much, actually.  Last I heard, as I recall, they were using quite reasonable-sounding compound mass margins, and by my calculations the engine performance margin is surprisingly large for an SSTO - the vacuum Isp on the Skylon C1 is 459 seconds and would have to drop to somewhere in the vicinity of 406 seconds to eliminate the payload.  Then there are the excess hydrogen burners (ie: ramjets), which are (according to Hempsell) modelled "very conservatively" and constitute a "hidden margin"...  probably less important now with the more efficient SABRE 4 engine cycle...

The performance differences between inclinations are simply a function of the large dry mass fraction to orbit.  The Shuttle exhibited the same phenomenon, and a properly-protected Falcon 9 upper stage will too, to some degree.  It says nothing about the margins used in the calculation of those numbers.

[QuantumG]

There's a Skylon thread...

[93143]

I don't expect this to take over the thread.  If I did, I would probably not have posted it, since I don't have the time for another punch-up with Robotbeat...

You may have a point, though...

[Robotbeat]

I don't expect this to take over the thread.  If I did, I would probably not have posted it, since I don't have the time for another punch-up with Robotbeat...

You may have a point, though...

Single-stage vehicles tend to have to use a lot of "tricks" to get into orbit reusably. Skylon does have lots of such tricks. 2-stage vehicles don't need to use as many tricks to get into orbit reusably, thus their development costs are much more likely to be lower. Lower dev costs means a lower flight rate is needed to get a reasonable return on investment, which makes two-stage reusable vehicles more realistic (IMO). Thus, it's not the "end-all, be-all" of RLVs when making comparisons with lunar propellant. That was my point there, and it seems pretty reasonable (and you may well agree with it).

Skylon may be superior in the end (argument is that there are no staging events thus operations costs can be minimized compared to a two-stager), and I wish them the best of luck.

[93143]

You do have a point there; SpaceX spent well over an order of magnitude less developing Falcon 9 than REL expects to spend developing Skylon.  I can't see SpaceX sinking $15B into F9R regardless of how difficult it turns out to be (or how small the payload ends up)...

Hopefully the flight rate will get high enough that even $15B is rapidly amortized and becomes irrelevant - that $2M/flight estimate for Skylon was a fully-commercial price with dev costs accounted for.  It may be an old number...

[Warren Platts]

I don't expect this to take over the thread.  If I did, I would probably not have posted it, since I don't have the time for another punch-up with Robotbeat...

You may have a point, though...

Single-stage vehicles tend to have to use a lot of "tricks" to get into orbit reusably. Skylon does have lots of such tricks. 2-stage vehicles don't need to use as many tricks to get into orbit reusably, thus their development costs are much more likely to be lower. Lower dev costs means a lower flight rate is needed to get a reasonable return on investment, which makes two-stage reusable vehicles more realistic (IMO). Thus, it's not the "end-all, be-all" of RLVs when making comparisons with lunar propellant. That was my point there, and it seems pretty reasonable (and you may well agree with it).

Skylon may be superior in the end (argument is that there are no staging events thus operations costs can be minimized compared to a two-stager), and I wish them the best of luck.

Bottom line: to beat Lunar propellant, cost to orbit has to get down to cost of Supersonic air transport. Ain't gonna happen....