Alan Boyle has a good rundown on the current state of play. I wonder, though about the assumptions underlying this comment:
To be competitive with other power sources, Maness figures that the powersat system’s launch costs would have to be around $100 per pound – which is roughly one-hundredth of the current asking price. Launch costs may be heading downward, thanks in part to the rise of SpaceX’s Falcon rockets, but Maness can’t yet predict when the charts tracing cost and benefit will cross into the profitable zone.
Launch costs to where? They’re that high to GEO, but not to LEO, and it doesn’t say where the satellite constellation will live. It’s going to be a long time before it’s a hundred bucks a pound to GEO, though though a robust market for LEO propellant depots will be a help in that regard. But we’re not far from having a thousand bucks a pound to LEO. Anyway, it would be nice to see more details on these things.
The bottom line, though, and the reason that I’m not that sanguine on the business prospects for SBSP, at least for base load, is this:
In addition to potential environmental concerns, large-scale solar farms can’t generate a steady flow of electricity at night, or during cloudy weather. But if engineers ever figure out a way to store up the intermittent energy generated by solar cells or wind turbines, at levels high enough to keep utilities flush with power, Maness thinks that would deal a heavy blow to his powersat dreams.
“At that point, I take my marbles and go home,” he said.
Yup. It’s not the technical risk of the space hardware and launch costs, but the risk of terrestrial competition as technology evolves, that is the biggest risk of all.
Year/Qtr
Laser and Power sat development (R&D)
Skylon development through first article (Taken from a Reaction Engine document but shortened by about half)
Flights per day
Flights per quarter
Cumulative flights
Multiplier tonnes to GEO per flight (Starts at 6 tons and as more laser comes on line, goes up to 25 tons at 8 GW.)
Cargo to GEO/quarter
Net cargo to GEO tonnes
Cumulative tonnes to GEO
Jigs and habitat tonnes (At GEO)
Tonnes for power satellites
Scrapped Skylons
Scrapped per quarter
Fleet size @ 1.5flights/day
Skylon production/quarter
Skylon prod cost per quarter (millions)
Lasers, 5 MW units
Mirror lift at 5 tonne each (mirror lift comes off the transport capacity)
Cumulative lasers
Laser & mirror cost at $10/watt (millions)
Power sat size GW (30 days of cargo) (size that could be built with 30 days of cargo)
Power sats GW/qtr
Cumulative GW
Propellant dedicated GW
Laser dedicated GW (these reduce the GW of power sats sold)
Added this quarter
Net power GW power sats to sell
Power sat sales at $1/watt net, millions
Interest (millions)
P/L for quarter (millions)
Cumulative PL (millions)
If you have more questions about the spread sheet, ask. I will also send you the excel file if you want it.
> Keith Henson Says:
> September 27th, 2009 at 11:00 pm
> How about more details? HTHL? Mass ratios and mass for both stages?
For the biamese the two stages are identical craft of course, and launch vertically belly to belly, and land on a runway. I have spreadsheets and diagrams and such (in various stages of messy. If intersted I’m at KellySt@aol.com ).
I based the weights around enhancing a shuttle Shuttle orbiter. Not as good as a clean sheet detailed design for it – but seemed adequate. if you feel more comfortable increaseing (doubling?) the reaction mas and vehicle weights for a given cargo mass it doesn’t really impact the cost to orbit much unless you assume higher servicing costs.
Loaded weight per stage, not including fuel or cargo, 60 tons.
LOx/RP 500tons per stage.
Cargo around 25 tons per flight.
Note the 4 F100 jet engines per craft add some high ISP thrust when you lift off. Depending on what you assume for drag to orbit – you get a capacity for maybe 40 tons to LEO per launch – but that seems optimistic.
For the second configuration with the Ram/rockets, I was assuming a single HTHL craft, with roughly similar mass rations and servicing cost per flight. Obviously you have half as many ships to service per flight – which is a big plus. At take off, mass ratios of 85% fuel/LOX, 2%(ish) cargo are good estimates, but as I said details like a catipult launch runway, landing gear design, how fastyour ramjets work, etc “adjust” the mass fraction numbers a bit.
Of course really you don’t care about mass ratios – you care of cost per pound. Generally worse mass ratios (if they aren’t insanely bad) give you better $/LB ratios. Which is why folks don’t deliver mail in Ferrari’s.
đ
==
> Gary Hudson says that if you are serious about reusing rockets,
> 15% structure is the minimum.
Be cautious of blanket %’s. For example the rule of thumb islanding gear has to be 5% (or something) of the TOW. The Skylon folks found that was driven by big soft footprint wheel and tires to not break runways (they’d rather build a tougher runway) and weight for the brakes. They designed brakes cooled by boiling off water. If you take off fine and don’t need to do a emergency stop fully loaded on the runway – you dump the water. It cut their landing gear weight way down.
Industry designs for RlVs frequently get lighter then 15% – so I think Gary might be over generalizing, and the Biameses 12% for vehicle without cargo seems reasonable.
> The best numbers I have heard optimistic experts are ~$300/kg
> to LEO and $500/kg to GEO. Thatâs 3-5 times too high for power
> sats to make economic sense.
The DC-X folks at McDac I knew were talking down to $200/lb to LEO with a highly utilized first gen DC-X shuttle. Down in the upper $10s per pound for a more advanced second gen one. Expectation is when state of the art and economics approach aircraft, you could get to $30-$40 per pound for LOx/Kero all rocket configs (Rutan recently quoted $40 for example) and well under that for combined cycle rock/ramjet or something.
These numbers also fit with historical cost ratios for fuel/propellant.
BUT – I mean a REALLY big but – is your assuming a million tons a year in lift market! The costs are HIGHLY driven by launch rate and servicing overhead.
Take my biamese example and assume STS utilization rates of 40 flights per decade, and a 30 year fleet service life (even ignoring NASA 4 fold higher cost structure). Your at
$10B for start up costs forRnD and base construction.
$2.4B to by 6 ships
$30 m a year in Labor for your 200 people that spend 90% of the time with no flights to prep for.
Say $500M a year to care and feed the base.
This all comes to about $30B for 30 years and 120 flights? 50k lb per flight – thats 6,000,000 pounds over 30 years, $5,000 per pound to orbit in total costs for the same vehicles that were delivering under $100 a pound in my other senerio.
Your million tons a year “market” means your spreading RnD costs, and costs and time to develop and perfect 2nd and 3rd gen systems – over you stagering start rate of the first few months!! Normal issues like convincing insurence to drop you rates because your safe and relyable — well a could weeks of your flight rates will cure all their concerns (or bankrupt you via loss of to many skylons if their fears were justified).
As for the $500 to geo costs you were told – I’ld ned to see what their assumptions were. Again I’ld lookinto a elecro mag tractor to lift SSPS parts.
PS
Tanks for the full row headers, and I’ll look back at the Skylon folks site for details on their dev costs figures.
Oh Keith,
as to “The best numbers I have heard optimistic experts are ~300/kg to LEO”. If you look up John Walkers old (1993) “A Rocket a Day Keeps the High Costs Away” ( http://www.fourmilab.ch/documents/rocketaday.html ) was nearly getting that assuming V2 level technology launching under 2 tons a day. So assuming you couldn’t beat that cost per pound with modern tech RLV’s?? I think your not listening to ver optimistic folks. Certainly not folks I’ve talked with or heard statements from in industry.
Ah Keith,
What is the surface area of all these SSPS’?
I was wodering how many square kilometers of collector were talking about here?
Oh Keith,
Having a senior moment here. If you realy want to hear a solid optimistic cost to lEO analysis. Check out the ’70’s DOE SSPS study. Appendix – D I think (I have a E-copy if you want) outlined the starraker. A 300 foot delta wing HTHL SSTO RLV 100 ton cargo rockwell design
http://www.astronautix.com/lvs/staraker.htm
It was projecting $20-$30 / kilo to LEO in ’78!
You also might be interested in spaceaccess http://www.spaceaccess.com who were working on something more applicable to your concept then Skylon – but seem to have got much farther along.
fyi.
“What is the surface area of all these SSPSâ?”
Sunlight in space is ~1.3 GW/km^2
At 15% efficient PV cells, close enough to 0.2GW/km^2 so 5 km^2 per GW.
60% efficient thermal cycle engines are 4 times smaller, 1.25 km^2 per GW but they need almost the same area if you count the heat radiators.
200 GW per year would be paving 1000 square km with PV. or 250 with reflectors.
There will be production problems with PV cells.
Light pressure has to be considered.
“Be cautious of blanket %âs. ”
The Skylon design is 49 t structure for 270 t TOW. 18%.
âWhat is the surface area of all these SSPSâ?â
I forgot a factor of 2 in there to get the power on the ground.
10 GW in space is only 5 GW on the ground.
So for PV, 10 km^2 per GW and 2.5 km^2 for thermal.
A PV 5 GW “standard model” would be 10 km by 5 km.
> A PV 5 GW âstandard modelâ would be 10 km by 5 km.
200 GW per year, you were charting out 40 years or so. 8,000 gw .. 1,600 “standard models”. End to end in Geosync thats 16,000 km end to end. Geosync is about 230 K km, in circumference. Places like mid-pacific would be undesirable. Isn’t it going start getting a bit crowded? Sats shadowing sats over the terminator – have to keep station keeping pretty tight. Hate to see a collision between these beasts.
…. ok maybe I would like to see it, but thats justme.
đ
===
>> âBe cautious of blanket %âs. â
> The Skylon design is 49 t structure for 270 t TOW. 18%.
Skylons Hydrogen fueled. Hydrogen fueled craft are much bigger and heavier then Kerosene fueled ones, and you need a bit more delta-V to a given orbit. Its why its actually easier to build a LOx/Kero SSTO then a LOx/LH one.
Ironic hey?
Off hand I don’t know of a SSTO proposal that uses kerosene.
Rotary Rocket thought they might do it, but they were running 8000 psi chamber pressure.
The trick with skylon is recovering the 20kWh/kg it takes to liquefy hydrogen. That’s where the energy come from to compress air to rocket chamber pressures.
“Isnât it going start getting a bit crowded?”
Harry Stine figured GEO would produce 177 TW using 10 GW units. I don’t know how he did calculated it.
> Keith Henson Says:
> September 29th, 2009 at 6:47 pm
>
> Off hand I donât know of a SSTO proposal that uses kerosene.
McDonnel Douglas was figuring it would be easier to do that then a LOx/LH SSTO. BlackHorse used Kero but Peroxide not Lox, but Lox would offer better performance for the same weight. And Mitch Burside C did analisis work on LOx/kero vrs lox /LH.
In general hydrogen sucks in rockets because of the extream dry weightpenalties. For example in the shuttle the LH part of the ET weights a ton for every 4 tons of LH. The LOX part (which being onion shaped is less volumetrically efficent ) holds about 34 tons of LOx for every ton of tank. Kerosene – not needing insulation – can get over 50 tons per ton of tank. Of if your a winged shuttle, you just use the wings and have little mass penalty.
Take a look at the Skylon cutaways. The vast bulk and hence weight is the LH tanks. To get the same amount of power you’ld need twist the weight of Kero, but a bout a 1/8th the volume.
What always bothered me about Skylon is it required tremendously tricky tech, and looked very brittle. Rocket engines that run off liquified air at low altitudes, and LOx otherwise. In flight air liquification systems using LH cooling. (Japanise tried this and couldn’t get it to work due to frost and air contaminent issues.) Huge LH tanks. A technological tour de force – but not getting trendous results for all that effort, and winding up with a huge fragile ship.
Seemed more a showy hot rod then a practical freighter.
Skylon doesn’t liquefy air. Cools it to -140 then compresses it to chamber pressure. They power the compressor with the temperature difference between ram air and LH2.
There are advantages in being low density.
But I am not particular, if hydrocarbons will do the job better, I say do it that way.
> Skylon doesnât liquefy air. Cools it to -140 then compresses it to chamber
> pressure. ==
Oh, true – though you’ld have the same issues with ice forming as you try to get air to -140
> == There are advantages in being low density.
Low weight is a plus – but low density fuel is a MAJOR disadvantage for a vehicle – especially a aircraft.
Space based solar power is an unrealistic solution. Not just because of the complexity and funding, but because so much energy and resources are required, compared to what you get back. We also need solutions today, not 20-50 years in the future. By then, there won’t be much of a world left.
http://www.selfdestructivebastards.com/2009/09/space-based-solar-power.html