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Cost to orbit for a manned craft

Posted by: Andy Hill - Thu Jun 09, 2005 12:52 pm
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Cost to orbit for a manned craft 
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Post Cost to orbit for a manned craft   Posted on: Thu Jun 09, 2005 12:52 pm
Following a discussion in the financial barriers section about estimates on the cost of a ticket for an orbital trip in 25 years time I did a bit of thinking about what might be possible now or in the near future to drive the cost per head down and come up with some interesting figures.

If we start off with the launch vehicle being the much loved and discussed (but as yet never actually flown) Falcon V and pack people into a super light weight craft built to the same dimensions as its current fairing (internal 3m diameter x 7.9m high) we could cram something like 30 people in the space easily in similar comfort to that offered by most airlines.

Now 30 people at 90kg is a total of 2,700kg and the Falcon's payload to a 400km orbit is 5,450kg leaving only 2,750kg for the spacecraft, not much to play with.

But if you consider the following things it seems that this might not be as big a problem as it appears.

A Merlin engine has a sea level Isp of 255s, if this were replaced with something like an RD-120 which has a sea level Isp of 338s the orbital payload could be increased significantly (sorry havent done the Maths yet) and/or the amount of fuel could be reduced. Even developing a better Merlin engine (10% more Isp) over the next decade would have a big impact.

Carbon nano-tube technology (remember I said near future) could be used to drive the weight of the Falcon Booster and passenger craft down which would improve matters still further, giving us more payload mass.

Now consider the following, the launch cost for Falcon V is quoted at $15.8M on the SpaceX website giving us a cost per passenger of about $526k. If we assume that this cost will come down in the future due to less fuel being required, less maintenance needed and possible savings due to many more flights being made (cheaper fuel, booster recovery and reburbishment) then it starts to look like maybe half the cost per head.

This is about 2 orders cheaper than that charged for a trip to the ISS by the Russians at the moment, not as good as the 3 orders touted in Collins estimate on the financial section but still pretty impressive. If space technology were to progress rather than remain fairly stagnated like it has over the next couple of decades it might be possible to see even bigger reductions in cost (not sure whether 3 orders could be reached but I am not so sure that they cant now).

What do you think is this reasonable with current technology or at least advances that are realistic? If so who is going to tell Elon Musk to get this built so I can start saving for a ticket? :)

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Post    Posted on: Thu Jun 09, 2005 1:56 pm
What are you trying to do Andy? Provoke me? Ok, I'll answer the questions raised in your last paragraph ... No, and no-one.

No to the first because its balanced on concurrent development of new technologies (life support for 30 people, re-entry body design to accomodate 30 people, super light weight craft, fabrication of useful CNT structures, assumptions about future costs, etc), and concurrency on such a scale as to require a huge chunk of serendipity (luck).

No-one to the second because Elon is too busy in the short term to be bothered with making spam-in-the-can launchers.

So if you can replace the words "the near future" with "a human life time" ... ignoring the silliness of life-extension nuts everywhere (that should ruffle a few feathers) of course ... then it would be harder to argue against. Lots of the things you mentioned might be in the pipeline, but that doesn't make them likely to be just around the corner.

DKH

EDIT: Actually, you didn't say anything about sending up LIVE humans ... nor did you mention de-orbiting them either ... hmmm, well I still think it's not a short term proposition ... even for group space burials.

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Post    Posted on: Thu Jun 09, 2005 2:14 pm
Dr_Keith_H wrote:
What are you trying to do Andy? Provoke me?


No, just bored on a Thursday afternoon and trying to drum up a conversation on a pretty dead forum. This is the Spaceflight Cafe, so you should take my post with at least a few grains of Sodium Chloride. :)

Maybe your idea about sending bodies into space might have some merit, isn't there a funeral company sending people's ashes up now? If they were already dead we could get a load of bodies in the same volume and cut cost per head even more plus you wouldn't have to cremate them first, re-entry would take care of it for you. :)

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Post    Posted on: Thu Jun 09, 2005 2:30 pm
I think at this stage pre-cremation would still be cheaper ... plus you could just jam them in a souped-up sounding rocket. It's not liked the bereaved are ever going to know ...

hmmm, sounds like a scam for the future ... I can see the headlines now ... "Shyster Fakes Orbital Burials from Kindersly" with the by-line "MH Enterprises admit casket contents barely reached edge of space, families outraged" ...

DKH

two points for whomever can guess what "MH" stands for.

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Post    Posted on: Thu Jun 09, 2005 2:43 pm
Dr_Keith_H wrote:
I think at this stage pre-cremation would still be cheaper ... plus you could just jam them in a souped-up sounding rocket. It's not liked the bereaved are ever going to know ...


Why bother sending a rocket at all, just throw the ashes on the roses in the back garden and say you sent them up. No people like to feel they are doing their best for the dearly departed (and normally pay more for the privelage) lets use a Falcon. Most wont know the difference between the I and V though so we could skimp on a cheaper rocket.

I like the title "The wrath of Brian" but he would probably botch it and we'd have body parts all over the place, not good for business at all.

When I said the forum was dead, this is not really what I had in mind. :)

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Post    Posted on: Thu Jun 09, 2005 3:27 pm
Hello, Andy Hill,

sorry that I mix in here by using Economics - but it has to do with the thread about Collins' estimation too.

You got the costs per passenger by dividing the Falcon V#s launch costs by 30 passengers. This means that you assume that those 15.8M launch costs are the costs caused by the weight in total.

But it may be that they are depreciations of fixed costs partially. It's a pity that up to now no team and no company has siad something about the strcuture of the costs.

SpaceX has to get back from their customers the costs of the recovery of the reusable stage(s), the development costs and the costs of the expendable stage too. So that part of the 15.8M that is depreciation of the reusable stage will degress quickly if it can be used for a number of launches somewhere above 20.

This menas that not onlx the number of passengers matters - but the number of flights carrying 30 passengers too. And the more launches to be expected (orders) the more the degression of costs of the production of propellant - in the long run theere will be economies of scale in propellant production I suppose if there are a lot of launches.

What makes it expensive really will be the expendabilitx of the upper stage. At that point the CXV as designed by t/Space is superior to the Faclon V - the CXV is reusable.

I don't want to go into the details about this economic argumant here and now - but I am going to think about a thread in the Financial Barriers section like that one in the Regulations section in which I expalined the complexity of regulations.



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Post Re: Cost to orbit for a manned craft   Posted on: Thu Jun 09, 2005 3:41 pm
Andy Hill wrote:
A Merlin engine has a sea level Isp of 255s, if this were replaced with something like an RD-120 which has a sea level Isp of 338s

Now consider the following, the launch cost for Falcon V is quoted at $15.8M on the SpaceX website
The $15.8M cost assumes a cheap, robust, reliable, reusable Merlin engine, not the expensive one use RD-120.


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Post    Posted on: Thu Jun 09, 2005 3:54 pm
Watch this thread mutate before your very eyes folks, from the makers of "Scientific Economic Estimate" here comes "Scientific Economic Estimate II" ...

Estamos Condenados

DKH

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Post    Posted on: Thu Jun 09, 2005 4:33 pm
Hey keith.. Looks like the XPRIZE FOUNDATION are nuts then... Since they are donating
$25,000 to mprize http://www.mprize.com/index.php?pagename=donors

"We've seen how prizes such as the X PRIZE and the Methuselah Mouse Prize can dramatically increase competition and innovation, and create interest for the public. With this contribution, we're signaling our belief that Prizes can not only take us into space, but help bring about breakthroughs in the way we live and age."

-Peter Diamandis
Founder, The X PRIZE Foundation

-- Sorry for going off-topic, but you didn't have to call us silly and nuts


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Post    Posted on: Thu Jun 09, 2005 5:57 pm
I was having a nice little nonsense conversation to pass a boring afternoon, I wasn't expecting anyone to inject realism in to it. Hurumph :)

I suppose I made the mistake of making the first post contain the germ of possibility. OK lets have 2 simultaneous conversations, one half nonsense and the other serious. Although I'd rather talk possible ways to launch lots of people on a Falcon V rather than economics (we already have that thread going).

Peter

I did say "something like the RD-120", meaning an engine with a much higher Isp using the same fuel combination should be possible not actually using something that would create more problems. This would give a Falcon V sized vehicle the possibility of carrying a larger payload.

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Post    Posted on: Thu Jun 09, 2005 6:36 pm
Hello, Dr_Keith_H

at least I myself don't want to mutate this thread :D .

But I can't but say that it may be that the thread about Collins' estimation seems to suggest that Peter might be the source of threads going spirally while Andy Hill really cuts the spirals.



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Post    Posted on: Thu Jun 09, 2005 7:35 pm
Andy Hill wrote:
I wasn't expecting anyone to inject realism in to it.
Realism is my middle name. And my first name. And last name. I really, Really, REALLY want a REAL space flight capability and I am just SOooooo tired of idle talk while I get another year closer to dying. :(

On the other hand, this forum fills the space between SS1 and (I hope) the first commercial suborbital tourist flights.


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Post Near Term Prospects   Posted on: Thu Jun 09, 2005 10:02 pm
I have made similar projections:

Andy Hill wrote:
Now 30 people at 90kg is a total of 2,700kg and the Falcon's payload to a 400km orbit is 5,450kg leaving only 2,750kg for the spacecraft, not much to play with.


For decades, the standard for well designed AIRCRAFT (with wings and serious propulsion), has been an empty weight of 40% to 50% the gross weight and payload capacity over half this gross weight. There are real reasons while this standard can’t always be met, and secondary reasons emphasizing either reduced development cost (with “good enough” limiting the investment), or a cosmetic and comfort emphasis.

It is hard to sustain an argument that a passenger launch and reentry capsule should be even this heavy. (Don’t talk about shaving weight off a NASA product – these were adapted from combat, “bullet resistant” hardware – with an emphasis on fast, “low risk” solutions - not optimized from the ground up. Delicate satellite hardware doesn’t get the same level of “pseudo protection”). “Pseudo Protection” is tough enough to shield you from imaginary risks, while offering no protection against real ones (re Columbia and Challenger). Note that a composite plastic “windshield” ejected at 200,000 feet has very little impact on orbital payload. Above that altitude there is virtually nothing to hit you that any spacecraft hull could stop.

The 1960s GE “MOOSE” reentry system is still a good design example, totaling 215 kg per astronaut, INCLUDING SPACESUITED ASTRONAUT, with retrorocket, heat shield, parachute and emergency equipment. Many of the systems can be upgraded, and made lighter, and the communal version can share much equipment, with further weight reduction. This minor reduction fits the 5450/30 numbers. To allow plenty of time for Space Station rendezvous, or nice orbital views during a multi-orbit abort, add 600 grams of oxygen per person to allow 24 hours of breathing time. Operational experience places the minimum heat shield weight below 5% of the reentry weight (9kg per person). The 24 pounds (11kg) of the CSU-4/P pressure suit is not prohibitive.

The real question is when people are going to start thinking in terms of real money, not government “pseudo money”. What are you willing to spend $3000 per kilogram to take along with you? Personally I will spend this to take my 95 gram Bible (but I will also shop for one half the weight). I won’t spend it for a hundred kilograms of solid metal, plastic and fused quartz to “shield me from nothing” (and severely degrade the view I paid to experience!) Remember that we are not discussing a 12 hour flight across the pacific, squeezed into a coach seat – we are talking about a 30 minute flight to a space station, so more Spartan accommodations are acceptable. And for a few dollars I can get a custom molded seat (probably integrated into a personal “luggage pod”).

I agree that the SpaceX price will come down, bringing the cost to orbit close to that quoted for a suborbital seat on “Virgin Galactic”. This is low enough to get miners, colonists and entrepreneurs into orbit, and on their way to deep space. Pioneering has always been expensive, historically costing all that the adventuresome can raise. These numbers fit that standard.

The question of when these trips will be affordable for a popular vacation is another matter. I am not particularly interested in this question for that time is too far off. Years before the Wright Brothers flew, investors were seduced with pictures of an unbuilt airplane carrying tourists over the Pyramids. International tourist air travel became affordable (but very special) about 1960, about 7 decades later. In the mean time, many thousands of people found both pleasure and profit in more specialized aviation work. For those who really care, there is no need to wait for spaceflight to become either an affordable pastime, or chic. Yet this question has an answer.

Using crude rocket motors, the total mass ratio to orbit is about 30, so a reasonable 200 kg orbital mass per person will require 6,000 kg of fuel (about 70% of that is Liquid Oxygen). The 1,800 kg of hydrocarbons (660 gallons of gasoline) is about what is used in an American family car each year. Without “highway taxes”, the cost is less than $1200. Oxygen is much less expensive, and should add less than $800. Efficient flight operations have costs close to twice the fuel costs, giving a $4000 per standard weight passenger ticket price. Note that logging 20,000 air miles (almost around the planet) uses an amount of energy comparable to orbital access (with perhaps ½ the fuel mass, due to greater overall efficiency).

Only decent engineering – WITH NO TECHNOLOGICAL INNOVATION - is necessary to get prices down to the $4000 level. It is likely that a focus on serious technical innovation, like buying race cars, will raise rather than lower the cost. Obviously an insane insistence on unnecessary “safety” or comfort features will raise the weight and cost as it does in every industry.


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Post    Posted on: Fri Jun 10, 2005 7:26 am
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Hmmm ... that's an interesting thing to happen. I guess I'm getting close to redlining on Sigurd's tolerance meter.

DKH

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Last edited by Dr_Keith_H on Fri Jun 10, 2005 12:55 pm, edited 1 time in total.



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Post    Posted on: Fri Jun 10, 2005 10:06 am
I think that it should be possible over the next couple of decades to develop a rocket engine of similar spec to the RD-120 but which is cheaper, more reliable and reusable. I was surprised to learn from the SpaceX website that the Merlin engine is only the second new US booster class engine developed in the last 25 years, the first being the RD-68 used on Delta IV. This is obviously an area where advances can be made if time and resources are put in.

Falcon V's payload capacity can be increased by 2,000kg if a RD-120 specification motor is used. Here are some figures from Astonautix.

..................................Merlin...................RD-120
Thrust........................318kN..................833kN
Engine Mass..............760kg..................1,125kg
Isp(sea level).............255......................338

Using 2 RD-120 motors instead of the 5 Merlins on a Falcon V results in a weight saving of 1,550kg while giving a thrust increase of 76kN. Because of the higher Isp of the RD-120s a fuel saving of 260kg can be made and with additional weight savings caused by carbon nano-tubes the 2,000kg should be reached. This gives the Future Falcon a payload of approx 7,500kg. Obviously a similar approach would need to be taken with the upper stage.

Using rpspecks 200kg per person figure from above we can now carry 37 people in our Future Falcon Ferry which would drive the cost down still further. Personally I think the number should remain at 30 or maybe even be reduced to 25 to allow passengers a bit more comfort, even if it is only a 30 minute ride to a space station or Moon cruiser. You could use some of that extra capacity to transport extra fuel/supplies/oxygen to your waiting ship.

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