Leaving early today to make our room reservation time at CONduit this year. Hopefully the hotel has wireless and I can find time to actually sit down and write. (Unless my wife has the laptop, which she usually does once she’s ‘done’ with the art and dealers rooms )

Randy

That’s close to what I got also, though the actual “main” point seems to be while your notional RLV price-per-pound of passenger to (and from) orbit was nominal “higher” than an ELV used to launch satellites to GEO one way given an optimal price point and a robust, low maintenance, fast-turn-around RLV (and no, none of that is a ‘given’ just because the vehicle IS reusable) your “people” flights increase and thus your market which increases your bottom line. The three “P”s that Jon listed (People, Propellant, Provisions) would seem to be a more ‘flexible’ market able to increase in a rather short time whereas satellite launch services is less flexible having long lead times and much less ability to change to meet the availibility of higher flight rates or other advantages of an RLV.

You also wrote:
>For the shuttle the capacity is given as x tons to orbit, y tons
>to ground. Usually everyone talks about price per kg to orbit.
>Price per kg to ground is a term I haven’t heard so far.

There is a simple and logical reason for that; there isn’t much to bring BACK from space. Other than people and some small mass allowence for scientific samples and such, less mass comes down than goes up. Jon mentioned (IIRC) that the “price” for people involves an assumption of both the cost to get them to orbit as well as returning them to Earth. Propellant and Provisions would essentially be “one-way” so someone who is looking to put those into orbit would reasonably expect to pay less for only ‘half’ the trip on an RLV, instead of the same ‘price-per-pound’ as a person who’s coming back down. So you will in all likely hood continue to hear “price-per-pound-to-orbit” most often used for quite a while to come )

However, Jon that brings me to something I wanted to mention but have had a very hard time getting down to writing. I will post it in a seperate post but I’m hoping you “re-visit” the comments on some of these older posts because I’ve screwed up my courage enough to actually post some rather interesting (and in some ways counter-intuitive also ) thoughts that I hope will get some responses from the many experts and thinkers who drop by your blog.

(Ya, I know… let me bleed myself a little and then jump into the Shark infested waters… Ah well who want’s to live forever? )

Randy

So your main point was to say that a RLV has a better chance to be cheaper than an ELV for two-way passenger transport missons than for one-way cargo transport missions? Well, that sounds quite intuitive to me, because RLVs need less additional mass to return a passenger than an ELV designed for one-way missions would need to return a passenger. Sorry for not recognizing it as the main point.

For the shuttle the capacity is given as x tons to orbit, y tons to ground. Usually everyone talks about price per kg to orbit. Price per kg to ground is a term I haven’t heard so far.

That doesn’t destroy my original point, but it does dilute it somewhat. That means that you can still get to elastic parts of the demand curve for people well before you hit demand elasticity for satellites. It still means that a launcher that’s barely competitive with ELVs for satellite launch might be able to eat their lunch entirely for launching anything that would require a capsule. But it does point to the need to be careful on how you design the people/cargo/propellant carrier to not go too overboard. It also underlines again the benefit of tugs, and possible innovative “docking/berthing” techniques…but those are discussions for another date.

So, I do concede you have a few points, I was just having a hard time understanding what you were getting at.

~Jon

Setting aside the question of whether your initial point was clearly stated (and I confess I missed it), I am glad you articulated your thinking, and the commentary has helped bring out a couple relevant points (whose truth value is TBD):

1. Start-up investors don’t need their returns to come from current operations. Rather, they need the company to demonstrate rapid growth and a narrowing between cash burn rate and operational income.

2. Humans will pay a very high per pound price for space flight. We have established price points for orbital + 1 week in station. We have not yet established the latent demand for orbital flight alone. We have established demand for suborbital flight. The experiential aspect is important.

3. The RLV design and mass increment for human flight, compared with an ELV + capsule, is a small (undetermined) fraction of the total. If one is starting to design a (sufficiently sized) LV, one might as well design it for carrying humans.

I likely missed some of it, but that is my “take home” message so far.

Yes, but even so that kind of rlv will inevitably be able to carry less payload into orbit than one designed for one way satellite launches.

That’s possibly true. But the market for LEO sats isn’t big enough to justify an RLV, and as I pointed out in this post, it looks like flying people is a better match for RLV characteristics anyway. And once you’ve designed a vehicle to be able to service those other markets, they rapidly become a lot more valuable anyway.

Also, if one wants the rlv to go to a spacestation then the payload drops by about half for a typical TSTO.

Compared to what? A due east 23.8 degree inclination payload to 200km orbit? Sure. But who actually buys payloads to that trajectory? The vast majority of the satellites in LEO are in polar or near polar orbits, and are at altitudes in the 500-1000km range (lots of polar, lots of sun-synch, and lots of satellites in the Iridium and Globalstar constellations, other than Molniya orbits there aren’t much else). Unless you’re going to require them to include a kick stage, launching to a space station is likely going to require less delta-V than launching to a typical LEO comsat orbit.

As for my comment about how much of a “capsule” or crew compartment can consist of crew or cargo, I was thinking of how much mass SpaceX’s Dragon would weigh if you were to strip it of propellant, heatshield, parachutes etc. It would still be about 3 tonnes – half the total mass, maybe more.

But if you’re doing an RLV, how much of that mass would still be needed? How much of the mass is stuff an RLV would need for launching people, propellants, or provisions that wouldn’t be needed for launching satellites? You still need propulsion, avionics, TPS, landing systems, etc…the only things I can see are different are a) a reusable pressure shell instead of tossing the payload fairing, b) rendezvous/prox-ops stuff.

I definitely agree that b is a potential issue, which is why I’m a fan of using tugs to offload as much of the station interfacing hardware as possible. But in the end, you’re not going to be able to close the business case for an RLV without reaching beyond the satellite market, so can you really avoid any of these subsystems?

~Jon

Seer: “Well, that assumes that the RLV isn’t designed from the start with the capability to return a full cargo load.”
Yes, but even so that kind of rlv will inevitably be able to carry less payload into orbit than one designed for one way satellite launches.

Also, if one wants the rlv to go to a spacestation then the payload drops by about half for a typical TSTO.
As for my comment about how much of a “capsule” or crew compartment can consist of crew or cargo, I was thinking of how much mass SpaceX’s Dragon would weigh if you were to strip it of propellant, heatshield, parachutes etc. It would still be about 3 tonnes – half the total mass, maybe more.

Even massive spacecraft like the ATV only have 40% * percent of their mass devoted to cargo.

* Volume might be the limiting factor.

An RLV that can launch more frequently with smaller payloads can participate in the existing satellite business with the right architecture. With an assembly/fuel depot in equatorial LEO, launching from the equator, a launch window is available every 90 minutes or so. If the satellite is launched in pieces and assembled and tested in orbit, satellite mission failure is minimized. For geosynchronous equatorial orbits, a Hohmann transfer orbit opens up every 90 minutes or so. The RLV can strap on some fuel tanks and ferry the satellite up to geostationary orbit and come back down. If the satellite breaks, the same RLV can go up and fetch it, bring it back down, fix it and replant it up there using fuel in the fuel depot. Being able to fix the satellite in LEO is way cheaper than building another one and relaunching from the ground.

For non geostationary orbits, a plane change is required. Perhaps one of those far lunar orbit plane change maneuvers (that I do not understand) can be used.

My $.02,

-Wayne

~Jon

~Jon