Reusible vs. Expendable - the Real Debate

Page 2 - Seeking answers about space? Join the Space community: the premier source of space exploration, innovation, and astronomy news, chronicling (and celebrating) humanity's ongoing expansion across the final frontier.
Status
Not open for further replies.
K

kelvinzero

Guest
rockett":3thewc89 said:
Quite true, the most efficient design is not a disintegrating totem pole, but a vehicle (regardless of configuration) that can be reused as much as possible. Just think what airfares would be if we junked a passenger airliner after every flight...

It would be very expensive! However there is a risk with reusable.

If you think biffing a 747 into the ocean after a single flight is inefficient, consider the cost of building a single reusable and not requiring another for 15 years. That would be like biffing all your factories and expertise into the ocean. They wont be there when you next require another. Also in the meantime there has been no evolution of design. This is pretty much what happened with the shuttles IMO.

I think we should be working on reusables, but we should keep building new prototypes even though this means in the short term reusables will cost even more than expendables. Keep them as small as possible so we can go through prototypes as quickly as possible. Fuel Depots could be a good justification for many small launches.
 
R

rockett

Guest
A few quotes from the article previously posted:

The Air Force estimates a reusable, fly-back booster could cut launch costs by 50 percent. For the pilot project, officials envision a sub-scale vehicle, at least 15 feet long, that would be launched on a sounding rocket or off of an aircraft for three test flights to demonstrate different rocket-back maneuvers.

The Air Force expects to award up to three $1.5-million contracts for studies then select one team for a $28.5-million contract to build the prototype. An industry briefing on the project met last week. (posted May 18, 2010)
NASA studied fly-back boosters more than a decade ago as part of a potential suite of upgrades to the space shuttles, but never pursued its development.

At least two companies hold patents for fly-back boosters: Lockheed Martin, which in 2008 quietly tested a sub-scale reusable fly-back rocket prototype and a firm known as Starcraft Boosters, founded by Apollo 11 astronaut Buzz Aldrin to develop low-cost alternative launchers.
http://news.discovery.com/space/air-force-reusable-rockets.html


A series of demonstrators is being planned by the U.S. Air Force to mature technology for the Reusable Booster System (RBS), its chosen replacement for the Evolved Expendable Launch Vehicle (EELV) family beyond 2025.

The first of the demonstrators, the Air Force Research Laboratory’s (AFRL) RBS Pathfinder, is planned to fly in 2013 to evaluate the “rocket-back” maneuver that would enable the unmanned first-stage booster to return to a runway landing at the launch site.
http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news/asd/2010/04/12/10.xml
 
S

SteveCNC

Guest
I see people talking about how we lose the ability to manufacture rockets if we don't do it all the time , to me from a manufacturers point of view I will never understand that kind of thinking . Do you honestly believe if I'm not working on some aerospace part that I will forget how to be a machinest ? get serious ! It has nothing to do with what I did last week or 20 years ago , hand me a print and I will make your part , it really is that simple . All you need to make another rocket is the design , most parts are made from billet not molded and so it isn't really that big of a deal if I haven't made part#xyz in 25 years or last week , to me it's the same part either way .
 
V

vulture4

Guest
SteveCNC":uwzb3vtj said:
I see people talking about how we lose the ability to manufacture rockets if we don't do it all the time , to me from a manufacturers point of view I will never understand that kind of thinking . Do you honestly believe if I'm not working on some aerospace part that I will forget how to be a machinest ? get serious ! It has nothing to do with what I did last week or 20 years ago , hand me a print and I will make your part , it really is that simple . All you need to make another rocket is the design , most parts are made from billet not molded and so it isn't really that big of a deal if I haven't made part#xyz in 25 years or last week , to me it's the same part either way .

Absolutely. You are a highly experienced machinist. But how long did it take you to reach that level of skill? Did you teach yourself from a book, or did you learn some things on the job or from other experienced people? Even if the rocket business disappears, you can use the same skills to machine parts for other industries. But suppose all the CNC machines, and all machine tools, were scrapped or shipped to other countries, and all the people in the field had to retire or find other jobs in real estate or banking? Suppose after 20 years someone finally needed a new part? How long would it take to develop new machines and learn to use them? Now consider at least 500 unique jobs just as complex, that didn't even exist before the Shuttle was built.. Does a tile with a tiny pit have to be replaced or repaired? How do you hand-bond a fragile ceramic tile to an aluminum skin strongly enough that it will remain in place at mach 25 but flexibly enough so that it the skin can flex? How do you ensure that the dehumidifyling cartridges in the air vents that equalize pressure in the space between the panes of the orbiter windshield are completely regenerated without removing them, a task that requires 100 man-hours because of the critical lines that have to be removed and reinstalled to reach it? Or should the designers have realized the problem when the system was designed, before it had ever returned from space for maintenance. When you machine a part, how do you know the part will be perform reliably, yet be easily maintainable if it fails? How do you know it cannot be lighter and still do its job? Or that it might last ten times longer if it were made slightly heavier?

Even in the aviation field there are still huge gaps in our engineering and technical capabilities. Airliners are susceptible to fatigue cracks that have caused ruptures, in a famous case a 737 came apart over Hawaii. It landed miraculously with a huge hole, but a flight attendant was blown from the craft in the air and killed. How do we inspect such huge structures for cracks hidden under paint?

These details have gradually been worked out by technicians and engineers working together for many years to maintain and repair reusable aircraft, and spacecraft. Over the years many systems on the Shuttle have been improved, but many could not be changed because of the basic design. With this knowledge many, many elements of a new spacecraft could be designed in ways that would make a new generation of shuttles safer, more capable, and less expensive to maintain. But to write everything down is almost impossible, because so many parts of a skill are based on knowledge that experienced workers do not even know they have, until they are asked the right question.
 
V

vulture4

Guest
rockett":10ycwhia said:
A few quotes from the article previously posted:

The Air Force estimates a reusable, fly-back booster could cut launch costs by 50 percent. For the pilot project, officials envision a sub-scale vehicle, at least 15 feet long, that would be launched on a sounding rocket or off of an aircraft for three test flights to demonstrate different rocket-back maneuvers.

The Air Force expects to award up to three $1.5-million contracts for studies then select one team for a $28.5-million contract to build the prototype. An industry briefing on the project met last week. (posted May 18, 2010)
NASA studied fly-back boosters more than a decade ago as part of a potential suite of upgrades to the space shuttles, but never pursued its development.

At least two companies hold patents for fly-back boosters: Lockheed Martin, which in 2008 quietly tested a sub-scale reusable fly-back rocket prototype and a firm known as Starcraft Boosters, founded by Apollo 11 astronaut Buzz Aldrin to develop low-cost alternative launchers.
http://news.discovery.com/space/air-force-reusable-rockets.html


A series of demonstrators is being planned by the U.S. Air Force to mature technology for the Reusable Booster System (RBS), its chosen replacement for the Evolved Expendable Launch Vehicle (EELV) family beyond 2025.

The first of the demonstrators, the Air Force Research Laboratory’s (AFRL) RBS Pathfinder, is planned to fly in 2013 to evaluate the “rocket-back” maneuver that would enable the unmanned first-stage booster to return to a runway landing at the launch site.
http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news/asd/2010/04/12/10.xml
This i fascinating stuff. The Air Force is moving into the future. NASA is moving into the past.
 
V

Valcan

Guest
SteveCNC":1hfl84kp said:
I see people talking about how we lose the ability to manufacture rockets if we don't do it all the time , to me from a manufacturers point of view I will never understand that kind of thinking . Do you honestly believe if I'm not working on some aerospace part that I will forget how to be a machinest ? get serious ! It has nothing to do with what I did last week or 20 years ago , hand me a print and I will make your part , it really is that simple . All you need to make another rocket is the design , most parts are made from billet not molded and so it isn't really that big of a deal if I haven't made part#xyz in 25 years or last week , to me it's the same part either way .

Its not so much you'd forget (though we cant build the saturn V because no one remembers how to build it and someone lost the instructions :( ) so much as you will have either moved on to a new job maybe in a new country or field or something like that.

We've lost alot of our manufacturing ability really fast sense for some reason certain people found our heavy industries "evil" and so taxed or made it cheaper to go overseas.
 
S

SteveCNC

Guest
While I am certain the population of quality machinest has decreased since the hay days of the 80's and 90's , it's not that bleak right now . I know of a few shops that have gone under since the 90's but there are new shops popping up almost as fast , I think it will be a long time before the art is dead . Aerospace may have their own set of specs they follow compared to most but in reality we hold the same tolerances every day on plenty of other things besides aerospace . Currently where I work now we mostly work on helicopter parts , but my buds over at spacedev toss me a bone once in a while , and I do some other very close tolerance work for an injection company . As much as I love doing aerospace work , there isn't much of it in SanDiego since Lockheed/Martin virtually closed down plant 19 and Rohr left a long time ago along with most of Raytheon . But it's not that aerospace is actually harder work , in fact a lot of it is quite boring and simple , the attraction is simply because it's aerospace . Most of the machinests that just had to stay in aerospace followed them to Denver/Huntsville/Marietta among others , the rest of us stayed here and made it work in the private sector .

Losing the design specs seems rather odd considering how the data of the day was stored on microfiche , I'm sure there's a set out there somewhere (probably some dusty old closet at Boeing in Huntsville) . Funny thing is I'm old enough to have used microfiche a lot from high school on into working as a machinest in the late 70's . In fact I was using microfiche till around the early 90's when pretty much everything went digital . Hopefully these days data backups are a regular thing so losing the knowledge of how to build things won't be a problem , as long as the human race doesn't become illiterate we're good .
 
N

neutrino78x

Guest
Valcan":n5dfnohi said:
We've lost alot of our manufacturing ability really fast sense for some reason certain people found our heavy industries "evil" and so taxed or made it cheaper to go overseas.

Actually the problem was that it is cheaper to make things in a 3rd world country where there are no environmental regulations, no minimum wage, no worker protections, etc.

--Brian
 
A

Astro_Robert

Guest
I thought part of the issue of trying to make new Saturn Vs was that the techniques have changed. My understanding is that even today, certain skills like brazing are somewhat rare and very specialized, and that Saturn used many such skills and techiniques, some of which may have been superceded or otherwise not currently in use.

Some may have gone away due to environmental regulations as well. I also understand that Shuttle for instance uses large Berrylium parts in certain areas and there are only like 1-2 machine shops in the country that handle this metal in this size today.

Now that many of these techniques used to make Saturn are no longer available, the parts cannot be manufactured they way they were originally, necessitating an almost complete redesign of the entire vehicle.
 
R

rockett

Guest
Astro_Robert":16a3d7o0 said:
I thought part of the issue of trying to make new Saturn Vs was that the techniques have changed.
Nope. We lost the plans. Only thing we could come up with was a J-2 engine that if I recall correctly was a museum piece that was reverse engineered. Became the J-2X for the Aries I second stage.
 
V

vulture4

Guest
Ironically NASA is about do it again, losing the capability to fly the Shuttle, and indeed all reusable spacecraft, by eliminating the USA shuttle workers.
 
H

HopDavid

Guest
kelvinzero":1w1rnd07 said:
rockett":1w1rnd07 said:
Quite true, the most efficient design is not a disintegrating totem pole, but a vehicle (regardless of configuration) that can be reused as much as possible. Just think what airfares would be if we junked a passenger airliner after every flight...

It would be very expensive! However there is a risk with reusable.

If you think biffing a 747 into the ocean after a single flight is inefficient, consider the cost of building a single reusable and not requiring another for 15 years. That would be like biffing all your factories and expertise into the ocean. They wont be there when you next require another. Also in the meantime there has been no evolution of design. This is pretty much what happened with the shuttles IMO.

I think we should be working on reusables, but we should keep building new prototypes even though this means in the short term reusables will cost even more than expendables. Keep them as small as possible so we can go through prototypes as quickly as possible. Fuel Depots could be a good justification for many small launches.

The assumption is another reusable wouldn't be built. But I believe reusables would be more likely to be have large production runs than expendables.

If 747s were thrown away each trip, nobody could afford a ticket and the market's nonexistent.

But since 747s are reusable and trips are affordable, there's much more demand for their services and therefore larger production runs of this vehicle.
 
K

kelvinzero

Guest
HopDavid":wjux0az6 said:
kelvinzero":wjux0az6 said:
rockett":wjux0az6 said:
Quite true, the most efficient design is not a disintegrating totem pole, but a vehicle (regardless of configuration) that can be reused as much as possible. Just think what airfares would be if we junked a passenger airliner after every flight...

It would be very expensive! However there is a risk with reusable.

If you think biffing a 747 into the ocean after a single flight is inefficient, consider the cost of building a single reusable and not requiring another for 15 years. That would be like biffing all your factories and expertise into the ocean. They wont be there when you next require another. Also in the meantime there has been no evolution of design. This is pretty much what happened with the shuttles IMO.

I think we should be working on reusables, but we should keep building new prototypes even though this means in the short term reusables will cost even more than expendables. Keep them as small as possible so we can go through prototypes as quickly as possible. Fuel Depots could be a good justification for many small launches.

The assumption is another reusable wouldn't be built. But I believe reusables would be more likely to be have large production runs than expendables.

If 747s were thrown away each trip, nobody could afford a ticket and the market's nonexistent.

But since 747s are reusable and trips are affordable, there's much more demand for their services and therefore larger production runs of this vehicle.

Not sure I follow.

Im not assuming another reusable won't be built, Im saying this is what happened last time.

It does not need to be the same next time, but we have to think carefully about why our next plan will be different. Also we should make sure our next plan will not trap us into another thirty years of stagnation if we got it wrong again. I would love to see reusables and I think we can do it.
 
D

dryson

Guest
Let's look at the two main factors of space exploration which are equipment and fuel. It takes x amount of dollars in euipment to get a six man pod into LEO and x amount of dollars in fuel to get that pod there. The only equipment that survives the journey is the pod the rest of the vehicle which I am sure costs alot does not survive and is burnt up which costs double the amount of dollars versus the cost of the fuel which is a consumable and cannot be reused. Lets say for instance the ORION lifter vehicle costs 3.5 billion to build minus the fuel and the pod itself. The pod can be reused upto ten times and then becomes junk so by the tenth use it has already paid for itself and is therefore an acceptible loss. The lifter vehicle itself now costs 7 billion because it cannot be reused and has to be built again to send the same pod back into LEO. See where cost of space exploration begins it's downfall?

The idea that I had and submitted to NASA involved using the same lifter vehicle that delivers the ORION pod into LEO but instead of just casting it off wings could be added. I forget the name of the seed but it was on the Discover episode that dealt with how seeds travel and how flowers are pollinated. The seed in question was a vine like seed that had paper thin wings that allowed it to be carried by the wind to places to germinate. The wings actually looked like wings. The same idea would work on a reuseable Ares vehicle. Heat shielding and avionics would need to be added to return the lifter vehicle to a recovery site where it would be picked up and used again thus elminating the spending of another 3.5 billion to build another lifter vehicle.

Here is an image of the idea which is based off of early conceptual shuttle designs.

http://en.wikipedia.org/wiki/Space_Shut ... gn_process

The design is the middle image on the left of the poster which looks like the main fuel tank used by the shuttle with wings that has an Ares type lifter vehicle attached to the top of it. To further cut down on cost the current design of the MPLM would be used to transport cargo into LEO.The vehicle could launch a set of four to five MPLM's to the ISS aboard the new design where the only loss would be the MPLM that would burn up upon it's jettisoning from the station after off loading it's cargo or the MPLM could be used as beacons by sending them further into space where inexpensive signal detection equipment could be used to look for comm signals from E.T.
 
V

vulture4

Guest
vehicle ..is burnt up which costs double the amount of dollars versus the cost of the fuel which is a consumable and cannot be reused
Excellent point,in fact the cost of the vehicle that is burnt up (or the ET and the SRBs that must be completely rebuilt in the case of the Shuttle) is typically about five hundred times the cost of the fuel, which cannot be reused.
 
S

SciFi2010

Guest
After reading the thread Expandable vs. Reusable I kept on wondering why expandable space vehicles are so much cheaper then reusable ones even if they were frequently used. The wings of the Space Shuttle design gave us the key to reusability, but not the cost-savings that should go along with it. Many comments were made about wings that they are dead weight in a space launch. They are actually right if the vehicle goes straight up at once. Wings are not the most efficient way to achieve reusability in a vertical takeoff (certainly if the wings of the RLV are large compared with its VT (Vertical Takeoff) launch system like the Space Shuttle). The main advantage of an expandable (or partly reusable) rocket with a vertical takeoff is the loss of weight by shedding a component during each stage of launch. In this case any kind of extra weight is a disadvantage. Wings might give reusability to a space vehicle, but if those wings are too big (compared with the VT launch system) that advantage might not compensate the extra costs of R&D, special materials, weight and maintenance. Especially if those wings do not add anything extra but dead weight to the take off. It might even be that full reusability in a vertical launch system might not even be desirable from a production/cost perspective and technological point of view. First the components will have to re-enter the atmosphere at Mach 10 and they will also have to withstand sea-water. Then the components will have to be recovered and transported. After undergoing that amount of stress a significant amount of detailed inspection is required. Finally the repairs and testing of components doesn’t help lowering the costs either. Any kinds of reusability in a vertical take-off doesn’t only add up in R&D and maintenance costs, but also in dead weight, while it lowers the possible amount of pay-load at the same time. Too often we associate reusability and SSTO with rockets that are launched vertical. If we shift from the idea from a reusable Single-STO with a vertical takeoff to a reusable 3- or 2-STO with a HTHL (horizontal take-off & landing) we might be able to avoid most of those problems.
A reusable 3-STO vehicle could be completely reusable, cost effective and easy to develop at the same time if all vehicles of the three different stages have wings and take off horizontally in comparison to a Vertical Takeoff SSTO
• Each stage vehicle can be designed (and shaped) to perform at their optimum according to their specific flight conditions (from subsonic to hypersonic speed) with common technology, which makes the R&D of a reusable 3STO relatively easy and cheap compared with a reusable SSTO:
1. First Stage of launch could be a fuel efficient lightweight conventional airplane (whether subsonic or supersonic), which is able to carry the 2nd & 3rd stage vehicles to a height of 50000 feet or more.
2. Second stage of launch could be a rocket with wings (like the wings of the *Pegasus (rocket) http://en.wikipedia.org/wiki/Pegasus_(rocket) ) and should also be able to land like an airplane.
3. Only the spaceplane in the third stage of launch would need full ablative protection. This means less complexity and weight for the first and second stage vehicles.
• The airlift provided by all the wings in a horizontal take-off could compensate the extra weight by the wings in the first stage of launch with less (wing-)weight at each stage of launch. It will also avoid rocket flight in the densest part of the atmosphere where more rocket fuel, and thus a larger launch vehicle, would be needed to overcome air friction.
• The 3STO vehicle can take off horizontally combined and each stage vehicle could land separately like an airplane, which makes all the 3 stages fully reusable and avoids most of the problems of a reusable vertical landing (see above).
• Other advantages are: less subject to launch-constraining weather, reduced national range scheduling constraints, minimum launch site requirements, and reduced range, safety concerns, and equatorial launch from the US

In this case I would prefer the 3M2-5 Myasishchev design ( http://www.ussr-airspace.com/index.php? ... cts_id=637). I think this Russian designs has the potential to become a fully reusable HTHL 3-STO if the 2nd stage rocket also would have wings (like the *Pegasus (rocket) http://en.wikipedia.org/wiki/Pegasus_(rocket)) and an autopilot for unmanned landings. By putting the 2nd and 3rd stage vehicles on the back of the carrier airplane there’s enough space for eventual wings of the 2nd & 3rd stage vehicles, which also could provide an extra air-lift. The (winged) rocket & spaceplane could be then launched like a military projectile from a conventional subsonic or supersonic airplane.
(*Manufacturer of the Pegasus rocket: Orbital Sciences Corporation. Most of the Pegasus was designed by a team led by Dr. Antonio Elias and the wing was designed by Burt Rutan! Check out the mission results!)


A reusable HTHL SSTO would require a lot of funding, fundamental research in new (lighter, stronger and heat-resistant) materials and rocket engine technology. The question is then where to start, how to do it and who are willing and able to do it. It is not unrealistic to design a reusable SSTO, but it simply would take too many hurdles, unknown factors and time to do that in one straight line. I think funding and R&D of a SSTO or any kind of new technology can give uncertain outcome. That is why multiple back-up plans are always needed. I think it would be a safe bet and good foundation to develop an air-launch to orbit system for medium cargo first and then to design a reusable HTHL 3-STO for commercial manned launch. In a later stadium the carrier airplane & rocket could be replaced a suborbital spaceplane (See Youtube: Peregrine Mission Animation by deanfilip http://www.youtube.com/watch?v=wHPck9PFzZc). If there are new developments in materials, launch assists (Maglev, etc…) and rocket technology (SABRE, LACE, etc…), then we could see a possible transition from a reusable muliple-STO into a reusable SSTO with HTHL. Even if it turns out at the end of route that a new RLV (for example the Skylon or the X-33) would not be capable to launch itself into orbit on their own there would still be a carrier airplane or suborbital spaceplane available (from former programs) to give them piggy back ride into LEO (or the new RLV like Skylon and/or X33 could become suborbital carrier spaceplanes themselves). By the way even Elon Musk from SpaceX has expressed his interest in air launch to orbit systems to lower costs further and to achieve full reusability at the same time. At the moment he will ofcourse stick with the common approach of vertical launch&landing, because this is the safest bet and fastest approach of manned launch into LEO and to the moon. On the long term however if he wants more "normal" folk on board then a more affordable and comfortable approach is needed. Cooperation in reusable air launch to orbit systems for cargo and humans between SpaceX, Virgin Galactic/Scaled Composites and Orbital Sciences Corporation in the near future would not be a bad idea as a first start of designing a reusable HTHL 3-STO and with a reusable HTHL SSTO as the finish line. Travelling into space might never be as cheap and easy as air travel, but it is all about making it affordable and doable for most people even if it is going to be an event that happens once or twice in anyone’s life-time for the coming decades. If we really want affordable and mass transportation to multiple BA inflatable spacestations in LEO or even to the moon, then I think this would be a doable path to take.
 
V

vulture4

Guest
I certainly agree that a reusable vehicle is essential and that at least two stages are appropriate. The question of air-launch vs ground-launch and horizontal takeoff vs vertical takeoff is difficult to answer without some actual testing to provide real data. That is a question the X-34, which was a two-stage horizontal reusable launch system (including the carrier aircraft) was designed to answer, and is a good reason why I believe cancellation of the X-34 program was a major NASA error. If anyone involved with this decision is in the forum, please speak up. Our objective should be discussion, not argument. Failing that, AFAIK there is still at least one X-34 prototype in storage at Ames. Any volunteers to see if it is still flyable?
 
Status
Not open for further replies.

TRENDING THREADS

Latest posts