Reusable 1st stage question

[kelvinzero]

Hi, there must have been many ideas for reusables stages (for 3-stage launchers) chucked around. What is the history of this and what has prevented this approach?<br /><br />A reusable first stage seems sensible:<li> extra mass is not so expensive as for later stages because you have not carried it as far.<li> Its a large proportion of the total craft, so I guess a reasonable fraction of the worth.<li> It would not have the reusability issues of heat shields.<li> Whereas the shuttle is only efficient for certain payloads a first stage could carry anything of the apropriate mass.<li> It is ok if your reuse method isnt 100% reliable.<br /><br />Also, about airbreathers. I keep seeing spectacular claims of usually single stage to orbit, but wouldnt they be practical for a reusable 1st stage much earlier?</li></li></li></li></li>

 

[vogon13]

IIRC, the Soviets recovered their (splattered) first stages and recycled the materials.<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[j05h]

The history of reusable first stages is a lot of talk and pretty pictures, with little real hardware. Fly-back stages were proposed at least as far back as Apollo, and Liquid Fly Back Boosters were almost builot for Shuttle. SpaceX is attempting to make reusable first stages for both Falcon 1 and 9, but that is a second-order concern of theirs. In Russia, they revealed a "Baikal" booster with fold-out wings and a jet engine for fly-back, but it has yet to actually fly. First stage reuse makes a lot of sense, if it can be made practical. <br /><br />Airbreathers, on the other hand, dont' appear to make sense at an operational level for spacelift. Hypersonic scramjets might make sense for fast passenger/cargo point-to-point flights, but not for getting into orbit. The goal is to get above the atmosphere as fast as possible because it is easier to accelerate without air resistance. Loitering in atmospheric flight while collecting enough LoX to make it to orbit is counterproductive. The time spent in reasonably collectible atmosphere for a normal rocket launch is only the first few minutes (at best) and that doesn't leave much time for collecting, compressing, liquifying and separating several hundred tons of LoX. It seems old fashioned, but the best rocket for spacelaunch is still a candle with a motor on one end and payload on the other. <br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[MeteorWayne]

That's a good point Jo5H.<br /><br />If you look at launch profiles to LEO, they go straight up as fast as they can to get above the atmosphere, then tilt over and work on gaining orbital velocity to reach 17,500 mph. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[thereiwas]

So you don't think Rutan's air-launch approach will work for orbital flights? I am not talking about the specific capabilities of SS1 or SS2, just the general idea of using an aircraft as the "first stage". Maybe even the t/Space dropped rocket method.

 

[j05h]

Air launch is completely practical. Air-breathing hypersonic RBCC multimode scramjets are not practical. Using a C-5 transport to air-drop a light rocket works and could lead to flexible, somewhat cheaper and more routine crew access. Building a spaceplane that delibrately stays in one of flight's most challenging regimes (hypersonic in middle atmosphere) is not a way to improve space access. <br /><br />For point-to-point transit, air-launched ballistic suborbitals are much closer to reality than RBCC spaceplanes. There are still massive materials and engine mass issues for these kinds of hypersonic craft. <br /><br />I'd give the "airship to orbit" a better chance of working than Orient Express/NASP type craft. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[kelvinzero]

I had the same impression about air breathers.<br /><br />That is really what I meant by asking how they can be remotely viable for SSTO if they havent yet found a use as even the first stage of a launch. (edit) this doesnt apply to scram jets since they are obviously no use as 1st stage, but there are a couple of other types.<br /><br />I was still interested to hear if jet engines ever had been considered for any sort of first stage though. It might not have near the performance of a real first stage, more like a launch platform that can raise a two-stage rocket above most of the atmosphere only imparting a small boost, but it could also return easily on remote control with little wear and be adapted to launch different rockets.<br /><br />I guess it all comes down to numbers which I guess people have looked at many times. Feel free to bombard me with links to all the failures <img src="/images/icons/wink.gif" /> <br /><br />(edit) btw, I read on wiki that the SaturnV 1st stage burns for about 2.5 minutes but the pressure of the air against it begins to drop after 80 seconds, ie atmospheric pressure drop outruns pressure from more speed.<br /><br />(edit) here is a link to something I just found, that looks like what I imagined.. http://www.alt-accel.com/pogo/pogo.htm .. I guess that qualifies as another example of 'lot of talk' <img src="/images/icons/wink.gif" />

 

[scottb50]

A two stage to orbit design with a fly-back first stage makes the most sense. I would use two similar versions, the medium lift version would use two liquid cores, two solid motors and three turbo-jet engines. The heavy would have four liquid cores, two solids and four turbo-jets.<br /><br />For launch the turbo-jets would operate the Max-Q to basically lift their own weight and that of their fuel. they would be re-started below 30,000 feet on descent for approach and landing as well as cross-range capability.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[qso1]

Tsto makes a lot of sense to me but the question that has to be addressed in order to see one come about is cost. I always see ideas for how to build one, but what will it cost to build and operate? This is what the 3Ps (Public, press, politicians) are interested in. If or when someone figures out how to build a cost effective system of any kind. We will finally see one become operational. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[scottb50]

The Shuttle, as well as Delta have proven we can reuse liquid engines a number of times. Shuttle has also proven solid motors can be refilled and reused. Turbojets are used on a daily basis and maintained on condition and not on hard tbo's. <br /><br />The only other thing is the basic hardware and software, which are easy and evolutionary.<br /><br />I get the feeling the current "vision" pretty much forgets we have already put a number of missions on the moon. Now we have to start from square one and reinvent everything. Unfortunately the reinvention doesn't sound a whole lot improved from Apollo. In fact it sounds like Apollo with a new coat of paint, something that will cost a lot and have short term publicity aspects, but will eventually be ignored because it is a dead end.<br /><br /> I get the current mindset to be we have never been to the moon <div class="Discussion_UserSignature"> </div>

 

[kelvinzero]

As J05H points out, flyback has been suggested for a long time.<br /><br />It sounds good, but there must be really good reasons why flyback first stages is not being used right now by americans, russians or anyone.<br /><br />Forgetting the future, what reasons have prevented its use up till now? Is it just that everything is pushed so close to its limits that checking eveything for reuse is only a little cheaper than building from scratch?

 

[qso1]

Reusing liquid engines is still expensive enough that it doesn't make a major improvement in flight rates. That might change a little on the Delta side in time. Shuttle engines are practically overhauled between use. The technical part however is not really the problem.<br /><br />Scottb50:<br />I get the feeling the current "vision" pretty much forgets we have already put a number of missions on the moon.<br /><br />Me:<br />I think its more like NASA could not get enough funding to properly develop a shuttle follow on and going back to the moon actually became easier because we had been there and shuttle hardware is able to support lunar missions in the form of shuttle LV derived LVs.<br /><br />I think the ultimate aim is to establish a lunar and eventual mars base capability and NASA also suggested the VSE could be utilized on manned asteroid missions. Otherwise, it probably will be seen as Apollo 2.0.<br /><br />Scottb50:<br />I get the current mindset to be we have never been to the moon<br /><br />Me:<br />Sad but true it seems. I run across people all the time that say we faked it. Maybe one day if NASA can get a lunar base going, and private industry gets lunar tourism going...the lunar hoax thing will quietly die. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[jimfromnsf]

To be cost effective, a reusable system has to fly 40-60 times a year.

 

[kelvinzero]

Hi Jimfromnsf,<br />Could you explain some more? Does this high figure come from having to keep the factories that produce the components from shutting down, for example?<br /><br />What type of reusable system are you assuming? Does this figure come from some study I could find a summary of on the internet?

 

[jimfromnsf]

It is to buy down the high cost of development of the reusable system.<br /><br />Per Dr. Antonio Elias, OSC Chief Engineer.<br />"Any fool can design a profitable EXPENDABLE rocket if it is guaranteed to fly 12-20 times a year (50-60 for a reusable)." He has stated many times on another website forum

 

[kelvinzero]

I found this mention, but it doesnt explain his reasoning:<br />http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=3911&start=106 <br /><br />Perhaps he is talking about a manned system that HAS to land successfully, not merely most of the time? <br />Hmm.. from context I guess he is talking about the pegasus which is unmanned... Interesting that air launch is used to avoid bad weather rather than get closer to orbit.

 

[jimfromnsf]

He is talking about a "reuseable" system. It has to land successfully to be reused, if not, costs go up. There isn't going to be continuous production of the vehicle. If there a continuous production of a vehicle, then make it expendable, which is lighter and simpler, therefore cheape. Economies of scale apply

 

[kelvinzero]

Oh ok.. That makes sense. Merely 9/10 reusable implies continuous production or several spares waiting around. Efficient continous production of a 9/10 reusable craft would mean a surplus that you dont have a market for.<br /><br />So what is your philosphy towards spaceflight? Do you have your own schemes to make it cheaper?

 

[thereiwas]

SpaceX says they have run the Merlin engine on their test stand for a total of 2,200 seconds, or the equivalent of 11 launches. I think that must be the regeneratively cooled version - I see spirals around the cone. So if they can find them and fish them out of the water, they could be re-usable. (I have to wonder about salt water though.)<br />

 

[kelvinzero]

salt water, and overly territorial hermit crabs <img src="/images/icons/wink.gif" /><br /><br />Hey, on the subject of airbreathers, I have just been looking at the aerospike engine which as far as I can tell from the link is not an airbreather at all, and was wondering if it could become partially an airbreather by throwing out a fuel heavy mixture on the side that is open to the atmosphere.

 

[scottb50]

Reusing liquid engines is still expensive enough that it doesn't make a major improvement in flight rates. That might change a little on the Delta side in time. Shuttle engines are practically overhauled between use.....<br /><br />One possibility is simplifying the engines, turbopumps being the biggest cost generators eliminating them would bring the cost down significantly. Numerous upper stages use pressurized propellant tanks, the only difference on a first stage would be pressure requirements.<br /><br />I posted an idea a while back that I still find workable. Instead of turbopumps a pressurized tank is used, two floating piston separate LOX and H2 with Helium between then. The Helium section is pressurized for launch and kept pressurized by using additional Helium first used to cool the combustion section and nozzle, the heated gas is then ducted to the Helium section.<br /><br />After returning it would be a simple task to vent the Helium back to storage, refill the tank and repressurize it. <div class="Discussion_UserSignature"> </div>

 

[qso1]

ThereIWas:<br />(I have to wonder about salt water though.)<br /><br />Me:<br />That is exactly what one of the major concerns was when Saturn-V first stage reusability was proposed. Protecting the engines from saltwater exposure was apparently too expensive to make reusability of the first stage economically practical. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[qso1]

vogon13:<br />IIRC, the Soviets recovered their (splattered) first stages and recycled the materials.<br /><br />Me:<br />The Russians, like us, have proposed reusable first stages for a long time. However, they have not ever actually reused a first stage to my knowledge. They may recycle materials but how much of that is practical? They proposed reusability for the Energia liquid strap on rockets and in images of the Energia, one can see fairing like attachments they called panniers. But Energia flew only twice and the first stages were never reused. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[vogon13]

Aluminum borscht cans, or aluminum first stages, you's just melts it all down and make new parts.<br /><br />Picking out bits of titanium and high alloy materials wouldn't be that hard either, just grab some <i>zeks</i> out of a nearby gulag, and put them to work.<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[kelvinzero]

Truely cheap recycling would be a fantastic breakthrough. Just drop your mangled rocket parts in one end and for the electical cost of smelting some aluminium you get a spanking new rocket out the other <img src="/images/icons/smile.gif" />