TSTO

[scottb50]

The four keys to efficient launches are re-usability, flexibility, rapid turn-around time and most important, available payloads. <br /><br />I propose a fully re-usable two stage concept; a vertically launched, flyback first stage and a second stage that stays in orbit and is used to build an infrastructure in LEO.<br /><br />Proven engines proven aerodynamics and the ability to transport an unlimited number of existing or future payloads. <br /><br />Using existing launch facilities and personnel would further reduce costs and development time while allowing time to develop simpler facilities and phase them in as they become available. <div class="Discussion_UserSignature"> </div>

 

[rybanis]

Man, TSTO discussion sure has been the rage lately.<br /><br />I'm going to have to read up on it. <div class="Discussion_UserSignature"> </div>

 

[mlorrey]

Sounds good, Scottb50. Now you just need a killer app to attract lots of payloads to justify the investment. What payload range were you talking about, and how were you planning on getting people into orbit (and back) to use the orbiting equipment as infrastructure?

 

[tomnackid]

Essentially you have just described the original Space Shuttle concept. However, I would argue that reusability INCREASES costs unless as mlorrey pointed out you have a reason for making lots of flights.

 

[nacnud]

For cheap TSTO I think you'd have a lot of work to do to get better concepts than the spaceX vehicles.

 

[mlorrey]

I would suggest starting small with a TSTO concept: launching nano sats. To start with, you can charge the most per kg in orbit of any size range (right now prices range from $20k-50k/kg) and there is the biggest market (at least 22 nanosats will launch this year at these prices). If you can get the cost per kg down significantly, you can increase flight rate. This is the consumer level market that needs to expand to make cheap spaceflight possible. Offering personal satellites IMHO is a killer app for this market. Another is mass produced NEO transponder probes to help improve tracking of earth-crossing asteroids.

 

[tap_sa]

<font color="yellow">"a reason for making lots of flights."</font><br /><br />A weekly service flight to a private space station? And downsize the initial vehicle payload to just a few (<=5) tonnes of supplies <i>or</i> ~6 passengers. Then you have a destination and a reason to fly often. Bigelow will put up the station using expendable vehicle.

 

[josh_simonson]

Isn't that almost exactly spacex's plan? They re-use the first and second stages, though they don't fly back. The best way to grow demand is to offer a cheaper and better product and let others come up with uses for it - and it won't happen overnight. I'd bet that once the refurbishment costs reach a certain percentage of their expenses, SpaceX will upgrade to a flyback or dry parachute recovery system. In the begining though, why spend the money on flyback and fast turn around if you don't have the demand to utilize it.

 

[tap_sa]

<font color="yellow">"I would suggest starting small with a TSTO concept: launching nano sats."</font><br /><br />I agree ... althought a 1 1/2 stage nano-Atlas would be fun too <img src="/images/icons/smile.gif" /> Spot-welded balloon tank from stainless steel etc.

 

[mlorrey]

I've also found that there appears to be immense demand for things that have been to space. Consumers are not discriminating between orbit and suborbit. It is the status of having "been to space" that is the cachet characteristic. Sounding rocket companies are offering to launch personal momentos (or items they sell from their websites) into space on suborbital trajectories for rates that come out between $40k-75k per kg (these items are measured in grams), and they are filling their manifests. Rings, business cards, postcards, pens, etc. that have been to space are ripe items for the collectibles market.

 

[tap_sa]

There's also the 'space funerals'. A cheapo nano launcher could send ashes to low ~100nm orbit where it would linger a few days and then reenter, with a very lucrative $/kg price.

 

[mlorrey]

Yeah, actually those charge pretty hefty, a few thousand bucks to boost only a few ounces of material. I doubt you'd need to attain orbit (as if the passenger is going to complain). If you do a trajectory right, you can sell all your passengers families vacations to the same resort where they can watch their loved one reenter. Given most meteors seen are the size of a grain of sand, these suckers ought to put on a decent fireworks show.

 

[tomnackid]

Hmmm, offer a "super deluxe package". Launch the entire body into a trajectory that will cause it to burn up on reentry (in a suitably showy manner). Call it "the ultimate cremation!" OK, I guess you would need something a bit more robust than a nano-sat launcher. On the other hand you won't need much in the way of a coffin/capsule. A light composite fairing that can withstand the launch loads. <br /><br /><br />To change subjects slightly (but still in the realm or TSTO): Does anyone know approximately how far Spaceship One could travel if it were going for distance rather than altitude? Back in the 50s sub-orbital or "boost-glide" rocket planes were supposed to revolutionize air travel. Point to point anywhere on Earth in 45 minutes. Who needs stinkin' scramjets. Guys like Tsien were planning to do it with rockets barely more advanced than the V2. Could we revive this concept. Air launching will alleviate the problem of take off noise and the sub orbital flight profile will probably keep the sonic booms high enough in the atmosphere to avoid damage on the ground. Could be a good stepping stone to developing economical orbital rockets.

 

[tap_sa]

Err ... umm ... I wonder if even orbital reentry speed is enough to guarantee complete 'burn up'. Remember Columbia, astronaut remains were found and identified <img src="/images/icons/frown.gif" />

 

[mlorrey]

Ah, good question. I've been looking into skip-glide range. Here's a good graphic of possible range for a given vehicle L/D ratio at the same start velocity:

 

[scottb50]

I was thinking 50-150,000 pounds. Payload Since you are returning and re-using the first stage it would be simple to tailor the main engine thrust and propellant load to meet the specific launch. The same would apply to the second stage engine, tailor the thrust and propellant load to the specific payload using the same hardware no matter what the payload.<br /><br />The second stage would carry the payload and because of it's flexibility it could be a one way cargo payload or a manned return vehicle of any number of configurations.<br /><br />The idea is basically a ground launched White Knight with a restartable, orbital second stage. The first stage would use four SSME's and two permanently attached, reloadable SRB's. The launch would use existing Shuttle mobile platforms and assembly facilities to begin with, phasing in newer equipment as it becomes economical to build it.<br /><br />The second stage is a propellant tank with two SSME's. Modified to allow re-starts and derated for longer life. <div class="Discussion_UserSignature"> </div>

 

[tap_sa]

<font color="yellow">"I was thinking 50-150,000 pounds. "</font><br /><br />Huh? The second stage would weight 5-7 times that (depending on staging speed), denoting the first stage to be Mother of All Flyback Stages.

 

[scottb50]

That means payload, not overall weight. <div class="Discussion_UserSignature"> </div>

 

[tap_sa]

Yeah what's the near term need for high flight rate (try to make it at least monthly) 50K-150K lbs payload delivery? Unless there is one this would end up just another hideously expensive 'shuttle derived' Saenger.

 

[spacefire]

For a fully reusable TSTO:<br />A big first stage that skips the atmosphere around the planet and returns to the launch site and a small second stage that actually achieves orbit seems to me like the best trade-off. Sure you need to worry about TPS on the first stage but you get free re-entry, and the second stage, the one that has to spend more time space, is tiny. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[scottb50]

The first stage would need more heat protection than Space Ship I, but nothing close to what the Shuttle needs. Eighty miles is not that much higher or rather faster coming down then sixty. Use turbojets, that basically carry their own weight on takeoff, for return and it could become pretty routine.<br /><br />The second stage would be the same Module as the two first stage cores, propellant tanks with two engines each. The SRB's would use the same Modules as housings. All you need to build a Module is two, identical, Segments and a tube. Two parts, what could be simpler?<br /><br /> <br /><br /> <div class="Discussion_UserSignature"> </div>

 

[mlorrey]

So this is just a paper concept, you don't expect to actually build it.

 

[scottb50]

I would love to build it, but on my salary it would be pretty hard to do and while I have a two car garage, I doubt it would be big enough. I think it could be built cheaply and easily and could make Space easily available to anyone. <br /><br /> <div class="Discussion_UserSignature"> </div>

 

[mlorrey]

That is why I'd suggest starting with a small version to lift small payloads. If you find a market for it, use that revenue stream to help finance building larger vehicles.<br /><br />For example, build two X-34 sized vehicles, one with a rocket engine which rides piggy back on one with turbojets. Start small.<br /><br />Right now, I'm starting small by building some small ramjets in my basement, which will be part of a ram/rocket 1st stage. Depending on the peak altitude, it may be marketable for carrying suborbital payloads for paying customers. Once it pays for itself, I'll develop an upper stage. Once this revenue stream starts producing returns, the profits will go into my X-106 concept.

 

[nacnud]

Cool! Have you heard of the Skybolt a simila(ish) project, but without the air breathing stage, from Starchaser Industries?