Author Topic: cheap reusable rockets?  (Read 14885 times)

Offline michaelwy

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cheap reusable rockets?
« on: 10/02/2011 10:26 pm »
http://www.tgdaily.com/space-features/58793-can-reusable-rockets-help-us-get-to-mars

Space X boss Elon Musk has declared that he is going to build a re-usable rocket which can substantially reduce launch costs. I wonder what the safety of such a rocket would be?
If successful, this could be the most important development for space. The only thing that would be better than a reusable rocket is a space elevator.
In the future we would be able to travel to the Bigelow space hotels using Branson's Virgin galactic. Or perhaps we could travel from London to Sidney in 3 hours via his Spaceship three.

Offline Jim

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Re: cheap reusable rockets?
« Reply #1 on: 10/02/2011 11:15 pm »
The only thing that would be better than a reusable rocket is a space elevator.

Space Elevators are scifi and not practical.

Offline Jim

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Re: cheap reusable rockets?
« Reply #2 on: 10/02/2011 11:16 pm »

In the future we would be able to travel to the Bigelow space hotels using Branson's Virgin galactic. Or perhaps we could travel from London to Sidney in 3 hours via his Spaceship three.


Virgin galactic has done nothing about orbital flight and point to point is not viable as a business.

Offline CitabriaFlyer

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Re: cheap reusable rockets?
« Reply #3 on: 10/03/2011 12:29 am »
How much fuel would it take for a Falcon 9 first stage to pull off that RTLS manuver?  Wouldn't this mean they would have to stage earlier in the flight?  I would think it would sacrifice a lot of performance.

But what do I know?  I am just an old country biologist who has given up calculus.

Offline michaelwy

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Re: cheap reusable rockets?
« Reply #4 on: 10/03/2011 02:01 am »

In the future we would be able to travel to the Bigelow space hotels using Branson's Virgin galactic. Or perhaps we could travel from London to Sidney in 3 hours via his Spaceship three.


Virgin galactic has done nothing about orbital flight and point to point is not viable as a business.

Branson has said that if Spaceship Two is a success, and 400 people have already signed up for a trip, he would build an orbital Spaceship Three. Branson has the money to make it happen, and as long as Burt Rutan is alive, he also has the brains. Point to Point travel would be possible then. It would have to be about the price of a Concord ticket. The rich and famous can travel between Europe and Australia in a few hours.

As for the Space Elevator, it can be built of carbon nanotubes, according to Michio Kaku.

Offline Bill White

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Re: cheap reusable rockets?
« Reply #5 on: 10/03/2011 02:07 am »
The lack of markets, not the lack of technology, is what stands between us and cheap access to space. IMHO.
« Last Edit: 10/03/2011 02:07 am by Bill White »
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Offline scienceguy

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Re: cheap reusable rockets?
« Reply #6 on: 10/03/2011 02:18 am »
The lack of markets, not the lack of technology, is what stands between us and cheap access to space. IMHO.

So what if there were people living on Mars? Then there would be a market for access to space. But we probably won't have people on Mars until there is cheap access to space...
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Offline Jim

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Re: cheap reusable rockets?
« Reply #7 on: 10/03/2011 02:24 am »

1. as long as Burt Rutan is alive, he also has the brains.

2 Point to Point travel would be possible then. It would have to be about the price of a Concord ticket. The rich and famous can travel between Europe and Australia in a few hours.

3.As for the Space Elevator, it can be built of carbon nanotubes, according to Michio Kaku.

1. Rutan has retired

2.  Not true, there are many issues with PTP that don't make viable

3.  One person's opinion doesn't mean it's true.
« Last Edit: 10/03/2011 02:24 am by Jim »

Offline michaelwy

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Re: cheap reusable rockets?
« Reply #8 on: 10/03/2011 09:02 am »

1. as long as Burt Rutan is alive, he also has the brains.

2 Point to Point travel would be possible then. It would have to be about the price of a Concord ticket. The rich and famous can travel between Europe and Australia in a few hours.

3.As for the Space Elevator, it can be built of carbon nanotubes, according to Michio Kaku.

1. Rutan has retired

2.  Not true, there are many issues with PTP that don't make viable

3.  One person's opinion doesn't mean it's true.

Rutan has retired? Well, that was sad. But I guess Branson has the funds to get a pretty good replacement.

What you say about PTP is interesting. Could you say something more about why you think it isn't viable?

Offline john smith 19

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Re: cheap reusable rockets?
« Reply #9 on: 10/03/2011 09:24 am »

1. Rutan has retired
True. He was the public face of Scaled Composites. Time will tell how diligent Scaled have been in growing replacements. I suspect they have been quietly encouraging new talent in relative obscurity until now.

Quote
2.  Not true, there are many issues with PTP that don't make viable
As there used to be with transatlantic or transpacific flight without refueling or changing planes. The issues relate to market size, is there a *return* market (from there to here) and how far apart those points are. The massively dumb ITAR rules don't help. Beyond that is the question of building a vehicle which can pay for itself and deliver operating expenses which allow its operators to make a profit before end of life.

ELV designers have not historically had to deal with these issues.

Quote
3.  One person's opinion doesn't mean it's true.
True. Materials are the #1 issue with space elevator concepts. It's not enough the material has to be *theoretically* capable of the load/unit mass it's got be available in the *quantity* to do the job. I'm not sure how many elevator advocates realize how much of this they need.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline ANTIcarrot

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Re: cheap reusable rockets?
« Reply #10 on: 10/03/2011 02:12 pm »
Watching the video the first stage takes off from Kennedy, imparts some sideward velocity, and then lands back at Kennedy? Or is supposed to be launching from the west coast? (Tampa? Cape Coral?) Despite usually on the pro side or RLV and CATS, this looks overly optimistic even to me, and I feel the need to ask questions like, "Is that a beryllium heat shield on the second stage?" :o

The video is certainly representative of some technologies that SpaceX could use to reduce the cost space flight, but I get the impression they've either glossed over or hidden some details, or the artists making it didn't pay a lot of attention to the engineers advising them.
« Last Edit: 10/03/2011 02:15 pm by ANTIcarrot »

Offline Jim

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Re: cheap reusable rockets?
« Reply #11 on: 10/03/2011 02:16 pm »

True. Materials are the #1 issue with space elevator concepts. It's not enough the material has to be *theoretically* capable of the load/unit mass it's got be available in the *quantity* to do the job. I'm not sure how many elevator advocates realize how much of this they need.

There are other issues, like orbital debris, weather, interference with other spacecraft, etc

Offline Jim

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Re: cheap reusable rockets?
« Reply #12 on: 10/03/2011 02:17 pm »

1. Rutan has retired
True. He was the public face of Scaled Composites. Time will tell how diligent Scaled have been in growing replacements. I suspect they have been quietly encouraging new talent in relative obscurity until now.



He was more than that.

Offline Bill White

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Re: cheap reusable rockets?
« Reply #13 on: 10/03/2011 02:37 pm »

True. Materials are the #1 issue with space elevator concepts. It's not enough the material has to be *theoretically* capable of the load/unit mass it's got be available in the *quantity* to do the job. I'm not sure how many elevator advocates realize how much of this they need.

There are other issues, like orbital debris, weather, interference with other spacecraft, etc

There also are economic issues.

Back of the envelope calculations quickly reveal that if space elevator price points are to fall below $500 per pound, staggering amounts of mass need to be lifted to LEO on a regular basis in order to amortize the capital costs of building the elevator, even if all of the countless technical challenges can be solved.

A $10 billion space elevator with ten year service life "costs" $121 million per month merely for the capital. (I used a generic financial amortizatrion program). This figures also ignores ongoing operating costs.

At a $1,000 per pound price target, an elevator operator needs to loft 121,000 pounds per month. At a $500 per pound price target, an elevator operator needs to loft 242,000 pounds per month.

= = =

Yes, I did do this on the back of a business envelope and may have dropped a few orders of magnitude.

Others are encouraged to check my math.
EML architectures should be seen as ratchet opportunities

Offline Hop_David

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Re: cheap reusable rockets?
« Reply #14 on: 10/03/2011 02:49 pm »

True. Materials are the #1 issue with space elevator concepts. It's not enough the material has to be *theoretically* capable of the load/unit mass it's got be available in the *quantity* to do the job. I'm not sure how many elevator advocates realize how much of this they need.

There are other issues, like orbital debris, weather, interference with other spacecraft, etc

There also are economic issues.

Back of the envelope calculations quickly reveal that if space elevator price points are to fall below $500 per pound, staggering amounts of mass need to be lifted to LEO on a regular basis in order to amortize the capital costs of building the elevator, even if all of the countless technical challenges can be solved.

A $10 billion space elevator with ten year service life "costs" $121 million per month merely for the capital. (I used a generic financial amortizatrion program). This figures also ignores ongoing operating costs.

At a $1,000 per pound price target, an elevator operator needs to loft 121,000 pounds per month. At a $500 per pound price target, an elevator operator needs to loft 242,000 pounds per month.

= = =

Yes, I did do this on the back of a business envelope and may have dropped a few orders of magnitude.

Others are encouraged to check my math.

And elevator throughput is seldom discussed. What speed can the elevator cars achieve? (recall they must travel 36,000 km to reach geosynch) How many elevator cars can the bean stalk support?

In my opinion the elevator would be far from the panacea a lot of people wish for.

Offline Epis

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Re: cheap reusable rockets?
« Reply #15 on: 10/03/2011 05:01 pm »
few days ago new interesting concept appeared from DirectP2  see at page
http://www.launchcomplexmodels.com/DirectP2/leviathan140.html
and I made some calculation of how much acceleration could deliver underwater launch tunnel 50m long for Falcon9 54m high rocket placed at the depth of 100m underwater.
so operation is simple:
- sink rocket to 100m depth down the 5.2m diameter 50m long   tube
- push out all water with air pressure 0.5 Mpa,
-clamp rocket and tube to lake / pool bottom if in ocean then to some counterweight.
- release rocket and tube from counterweight
- blast off tube pressure cap to release air pressure
- and the rocket will take off from 100m water depth at the beginning with 30m/s2 acceleration then when rocket aligns with tube fire some small Solid rocket engines to create hot high pressure gases and blast out of tube with more than 30m/s so at the end total launch assist runway length would be 150m long  with average 20-30m/ss acceleration speeds of 77-94 m/s could be reached that would result in ~17% fuel saving of rocket first stage compared to launch without acceleration, that fuel saving bonus could then be used for first stage Vertical fly back and landing.
performance could be increased when launched at higher altitude mountain top lake, problem is that there are no deep high altitude lakes so I guess someone would need to find some >5km altitude volcano crater and make some digging, basically make small pool and pump in water, that would be then launch pad.
rockets first stage could fly back to high altitude pool and land there for next launch, so basically second stage + payload would be parts that will need transportation to launch place. if second stage could make trip around the earth and land back to pool then it will be more economical, will save time and money and high transportation costs to mountain top.
mountain spaceport infrastructure could be used in future for other mountain slope linear accelerator project research and development to reduce further cost of launches.

Offline Jim

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Re: cheap reusable rockets?
« Reply #16 on: 10/03/2011 05:10 pm »
few days ago new interesting concept appeared from DirectP2  see at page
http://www.launchcomplexmodels.com/DirectP2/leviathan140.html
and I made some calculation of how much acceleration could deliver underwater launch tunnel 50m long for Falcon9 54m high rocket placed at the depth of 100m underwater.
so operation is simple:


Again you fail.  It is not simple nor does it provide an advantage.

Offline A_M_Swallow

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Re: cheap reusable rockets?
« Reply #17 on: 10/03/2011 07:25 pm »
{snip}

And elevator throughput is seldom discussed. What speed can the elevator cars achieve? (recall they must travel 36,000 km to reach geosynch) How many elevator cars can the bean stalk support?

In my opinion the elevator would be far from the panacea a lot of people wish for.

The top speed is about 200 mph to 250 mph.  The speed limitation is the maximum force you can apply to the ribbon and the energy your solar panels can deliver.  The main acceleration is gravity which varies with height.

Throughput is likely to be 1 launch per day, timed 2 hours before sunrise.

The cargo vehicles will probably be expendable, the elevator has to stop launches during descents.

Offline michaelwy

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Re: cheap reusable rockets?
« Reply #18 on: 10/03/2011 09:00 pm »

1. as long as Burt Rutan is alive, he also has the brains.

2 Point to Point travel would be possible then. It would have to be about the price of a Concord ticket. The rich and famous can travel between Europe and Australia in a few hours.

3.As for the Space Elevator, it can be built of carbon nanotubes, according to Michio Kaku.

1. Rutan has retired

2.  Not true, there are many issues with PTP that don't make viable

3.  One person's opinion doesn't mean it's true.

I found this video interview with Burt Rutan in which he practically answers my questions. (He keeps saying that Al Gore created the internet.LOL)

http://bigthink.com/ideas/18881

But it looks like Rutan agrees with you about point to point flight.
« Last Edit: 10/03/2011 09:01 pm by michaelwy »

Offline gbaikie

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Re: cheap reusable rockets?
« Reply #19 on: 10/03/2011 09:46 pm »

In the future we would be able to travel to the Bigelow space hotels using Branson's Virgin galactic. Or perhaps we could travel from London to Sidney in 3 hours via his Spaceship three.


Virgin galactic has done nothing about orbital flight and point to point is not viable as a business.

Branson has said that if Spaceship Two is a success, and 400 people have already signed up for a trip, he would build an orbital Spaceship Three. Branson has the money to make it happen, and as long as Burt Rutan is alive, he also has the brains. Point to Point travel would be possible then. It would have to be about the price of a Concord ticket. The rich and famous can travel between Europe and Australia in a few hours.

Let's see after a dozen or so joyrides. Maybe we will see it in 2012.

"As for the Space Elevator, it can be built of carbon nanotubes, according to Michio Kaku. "

Carbon nanotubes would worth more than the high quality steel used in bridges, but at the price steel [or even if free] Space Elevators can not
get people into space cheaper than chemical rockets.

The fundamental problem is amount of payload and the time it takes to
get into orbit. How fast can a train go? And do trains travel faster if going straight up.
Or what is fastest elevator in the world? And if there was any need could one fairly easily double or triple it's speed?
Why isn't "space elevator technology" used in "normal" elevators. Such technology is cheap and energy efficient, no?

I think if there is any value to a space elevator it will be in bringing people and/or cargo [or stuff] from space to earth. Not a pressing problem at the moment.

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