Reusable 1st stage question

[kelvinzero]

Hey... Is the ares reusing the first section? This article mentions parachute and recovery of the first section.<br /><br />http://www.spaceflightnow.com/news/n0708/28ares1x/

 

[jimfromnsf]

That is the whole reason for using the shuttle booster on Ares I, recoverability/reuseability

 

[kelvinzero]

Ok so im a dope <img src="/images/icons/smile.gif" /> Thought it was just the ares v. Still reckon someone might have mentioned it to me on a thread titled 'Reusable 1st stage question', asking why we dont reuse the 1st stage <img src="/images/icons/laugh.gif" /><br /><br />But you still argue that this is less cost effective? does the 40-60 launch/year figure apply to this? Otherwise, how much is saved by reusing it?

 

[jimfromnsf]

it is not so much as saving money but to be able to do post flight inspection <br /><br />the 40-60 flight thing applies for totally resusable systems

 

[kelvinzero]

I just had a minor (and uninformed) idea related to reusable rockets<br /><br />To solve the problem of the intense heat wearing out the combustion chamber and nozzle, couldnt the combusting propellent push against trapped uncombusted fuel?<br /><br />For example suppose we have a chamber filled with with cool hydrogen gas under pressure.<li>There is a small circular hole in one end of the chamber.<li>What prevents the hydrogen rushing out immediately is a permanent explosion blocking the exit.<li>The chamber remains cool and at constant pressure because liquid hydrogen is continually pumped into it to replace the hot hydrogen that leaks into the area of combustion at the portal, taking part in it.<br /><br />It might need a lot of tweeking to work at all, but I can also imagine that the bell shaped 'nozzle' formed by the explosion pushing against the wall of cool gas being adjustable for different conditions during flight.</li></li></li>

 

[vogon13]

Sounds like the film of alcohol fuel Von Braun used in the V2 thrust chamber.<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]

It sounds like any of a number of different regenerative cooling techniques. Sometimes cool fuel is flowed through tubes wrapped around the engine bell. Other times, it is an evaporative "sheath" injected inside the bell.<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[kelvinzero]

Hi Vogon13 and JO5H,<br />Got any links or other info? I googled around for the film and alternate regenerative cooling techniques but couldnt find anything.<br /><br />Also, what actually does make rocket engines hard to reuse without extensive refurbishment? I had assumed it was the wear on the chamber/nozzle caused by the massive heat. Is that right?

 

[jimfromnsf]

It is the turbopumps. The blades and bearings. Chamber and nozzle are secondary

 

[kelvinzero]

Oh, ok. Thanks Jim.

 

[vulture2]

You can certainly augment a rocket engine with external air, but just puting fuel in the airstream won't work; the air has to be compressed by a ramjet-type intake duct so that it can expand again to yield thrust. <br /><br />Regarding the question of reusability, if our objective is just to fly a few missions and then can the program, then there's no point in putting together a reusable system because it has a higher development cost. This is the way the currrent "Our job is to fly four missions a year" NASA thinks. But if we see our job as to develop the technology that will make human spaceflight practical for somebody other than a handful of thrill-seeking billionairs, then minimizing the cost of flying a very limited number of missions is irrelevant. We must develop a reusable system because an expendable can NEVER achieve low operating cost, therefore it CANNOT achieve the goal. <br /><br />Of course the shuttle didn't accomplish this, but it was our first attempt, designed before we had ANY flight experience with reusable systems, and (in an unforgivable moment of hubris) was designed on paper in final form with no prototypes or develomental demonstrators. The total cost for all the fuel (i.e. energy) is well under 1% of the mission cost. Jetliners of similar complexity have a fuel cost of at least 60% of mission cost, and there's no physical reason why a reusable launch vehicle couldn't approach this. Giving up on reusable spacecraft because the Shuttle didn't meet its cost spec is like flying nothing but the Wright A flyer for twenty years, then deciding heavier-than-air flight is impractical and going back to balloons.<br /><br />With regard to the reusable first stage, obviously it would only make sense if our goal is to develop new technology. What a concept! If so, we would start like Armadillo et al; with a subscale, suborbital prototype and slowly build up knowledge of reusability and practicality from there. Hey, that was what we were doing with the X-33,

 

[thereiwas]

Hear hear!

 

[kelvinzero]

I hadnt really thought that reusable rockets can be regarded as a success even if not cheaper at the current usage levels. Of course that is true.<br /><br />This is reallyoff topic to the thread but I hope we dont give up on the moon. Im not so interested in putting people there as just maintaining development of systems that can actually land something on it. Once we are continually landing the latest technology on it there is motivation for a much wider selection of scientists to keep bashing their heads against the problem of how to exploit the moon. I'd like to see more students in biology considering artificial biospheres and more students in chemical engineering dabbling with simulated regolith.

 

[kelvinzero]

btw ..(another vaguely reuse-oriented question)..<br /><br />Why are round parachutes used in most space applications? What about something more like a paraglider? One advantage could be to bring you closer to where you want to land, but also couldnt a computer controlled glider parachute convert its horisontal momentum into an upwards swoop at the last moment, landing with zero vertical velocity if timed right?

 

[bpfeifer]

"We must develop a reusable system because an expendable can NEVER achieve low operating cost, therefore it CANNOT achieve the goal. "<br /><br />While I personally prefer the idea of reusable vehicles, I'm not certain your definitive claim is actually true. Wherein lies the greatest cost associated with launching spacecraft? If it is in the production of each vehicle, then you are correct that reuables are ultimately more cost effective. If opperational costs are greater, then single use and reusable vehicles are equally bad.<br /><br />I suspect that the latter may actually be true. In which case, if you want to lower launch costs, you must remove/automate as much of the launchpad activity as possible. This requires two things.<br /><br />First you must design boosters and spacecraft with automation in mind from the begining. Second you must build the infrastructure to support it. We've been sending ships out on the ocean for centuries, but there's a huge difference between dragging a Viking longship up on the beach, and pulling a modern containder ship up to a modern dock with crains, and navigation aids and the rest. It only takes a week and a small crew to unload and reload a container ship today. This was unheard of only 20 years ago. How can we apply similar logic to space launches? <div class="Discussion_UserSignature"> Brian J. Pfeifer http://sabletower.wordpress.com<br /> The Dogsoldier Codex http://www.lulu.com/sabletower<br /> </div>

 

[vulture2]

>>Wherein lies the greatest cost associated with launching spacecraft? If it is in the production of each vehicle, then you are correct that reuables are ultimately more cost effective. If operational costs are greater, then single use and reusable vehicles are equally bad. <br /><br />This is a good point. The critical parameter is the number of man-hours of work needed to recover the vehicle after landing and prepare it for the next launch. This cost was not accurately predicted during design of the Shuttle. The flying of technology demonstrators would permit accurate estimates of turnaround cost and identify design changes that could minimize it. The extremes can be indicated by comparing the Shuttle with the X-15 or SpaceShip One, which could be recovered and prepared by a crew of (my guess) 20 people in one week.

 

[scottb50]

he extremes can be indicated by comparing the Shuttle with the X-15 or SpaceShip One, which could be recovered and prepared by a crew of (my guess) 20 people in one week....<br /><br />With that comparison you would also have to build a B-52 or White Knight for every launch. The same holds true for a re-usable capsule. <div class="Discussion_UserSignature"> </div>

 

[vulture2]

>>With that comparison you would also have to build a B-52 or White Knight for every launch. The same holds true for a re-usable capsule.<br /><br />Total operating cost would include the turnaround cost for all elements, including a launch aircraft, if used, not the cost to design and build it. In a commercial operation the cost of designing and building the carrier aircraft may have to be amortized across the actual commercial flights of the aircraft. In a technology development effort the cost to design and develop the system is, in theory, amortized across all the future systems that the new technology will make possible. That was the origianal mission of NASA, to support technology development that industry needed but could not do by itrself because the risk was too high or the payback more than a couple years in the future. <br /><br />I am somewhat skeptical that reuse of the CEV capsule will prove practical because of the decision to land in the ocean, which can cause corrosion. However, one Gemini capsule, which did land in the ocean, was flown twice (unmanned).<br /><br />As mentioned, the main motivation for recovery of the Ares booster seems to be for inspection. It is not economical to reuse the SRBs mainly because they must be totally disassembled and then rebuilt between flights.

 

[scottb50]

It is not economical to reuse the SRBs mainly because they must be totally disassembled and then rebuilt between flights....<br /><br />Especially when they have to be sent to Utah for propellant loading and back to Florida for reassembly.<br /><br />If the were part of a return first stage they could have propellant reloaded at the launch site, it could be loaded into inserts in Utah, if politics are still a concern, but it would be much simper then towing it to shore, cleaning it and shipping it by rail 2/3 of the way across the country. Especially because a certain Senator insisted it had to be done that way, <div class="Discussion_UserSignature"> </div>

 

[vulture2]

The shipment to Utah is certainly a factor in the cost, however the refurbishment process requires that every part be disasembled and checked for cracks by magnafluxing or similar processes. This requires removal of all paint and coatings. At one time every bolt was sand-blasted to remove the cadmium plating, the crack check procedure was done, and then the bolt was replated. More recently money has been saved by throwing away the bolts and replacing them. A great deal of hazardous waste, including asbestos-based insulation removed from the inside of the booster by hydrolasing, and sandblasting media contaminated with cadmium, must be disposed of after each flight, and that costs money for hazardous waste disposal, tracking and shipping, training of personnel, etc. In addition of course the segments nust be separated an later reassembled, and the nozzel (which is not reusable) replaced. The people who do this do a great job; nearly an impossible job. But it cannot be done cheaply.<br /><br />I only present this detail to give you an idea of how impossible it would be to rebuild the SRBs for a cost significantly less than building new ones. If we want affordable access to space we need a vehicle we can gas up and fly again, and we need to test flying prototypes to make sure the maintenance cost is affordanble. <br /><br />

 

[scottb50]

Thats why you build a high strength housing and cast the motor segments in throwaway inserts. Instead of the entire motor being various segments the propellant segments are inserted into a fixed, single piece, housing. <div class="Discussion_UserSignature"> </div>

 

[starfhury]

Personally, I think we need to look at other engine technologies. Time and time again, it comes down to the propulsion systems. We got rid of piston engines in commercial aircraft so that we could use jet engines. The real truth of the matter is that our current chemical rocket engines are really not up to the task. It's the inefficiency of these engines that are at the heart of the problem. People keep dallying around that issue. If we had an engine that imparted twice as much energy to the propellant as current engines, we can reduce propellant usage and vehicle size which goes along ways to making things less expensive so that more time and energy can be dedicated to re-useability. Hybrid technology in cars has been on the rise for a while now. Was there any work done to try to hybridize liquid fuel engines?<br /> <br />This might be impractical, but my idea was to combine an arcjet with a liquid fuel engine to enhance performance and efficiency of the booster rocket. The idea would be use something like a power grid and ultra capacitors to help impart even more energy for each given unit of propellant. Instead of depending purely on the chemical reaction to impart all the energy to the propellant, we can enhance it by piping in energy stored in capacitors drawn from the power grid. This would help reduce the overall weight and size of the rocket since you would not need as much propellant to get the same amount of work done. The capacitors only have to have energy for a few minutes of flight to provide boost for the second stage. Some of the weight savings can be used to add jet engines to make the stage reusable and help reduce cost.<br /> <div class="Discussion_UserSignature"> </div>

 

[jimfromnsf]

Very impractical. The additional "efficiency" is more than offset by the weight of the capacitors. Chemicals have a higher energy density for launch<br /><br />Jet engines are even more impractical for launch

 

[vogon13]

Correct.<br /><br />How long would a capacitor (even a 1 Farad !) operate a 1500 watt heater ??<br /><br />Yeah, not long at all.<br /><br /><br />And this idea is to super heat tons of stuff per second. Power of the Space Shuttle main engines is a respectable fraction of the total output of the entire US power grid. Imagine the disruption and surges of trying to do something like that!!<br /><br /> Another idea that if even the barest molecule of mathematics was used it would evaporate like a snow cone in a steel blast furnace.<br /><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>

 

[nuaetius]

There is no magic in the rocket equation. The only thing stronger than a Liquid Oxygen / Hydrogen rocket is nuclear rocketry... and that is political suicide.<br /><br />Rockets will be big and expensive one way or another until we have a Space Elevator, Teleporter, or some other unobtainium.<br />