Can Smaller Rockets with Less Fuel Mass Lower the Cost of Space Travel?

[chandrahas]

Rockets are quite expensive and it takes about 2000 to 10000 dollars to place 1 pound into orbit. So I was wondering: Is the size or the fuel mass of a rocket a big concern or will it be of no help economically if we make smaller rockets with less fuel mass for the same amount of payload. Assuming we can do this somehow.

Thanks

 

[mfb]

Fuel costs are typically about 1% of the total launch cost. It is negligible for current rockets. More fuel means a you need a larger rocket and more thrust (to lift all the fuel), however, and that increases the construction cost.

 

[chandrahas]

So even though the fuel costs are low, the cost to build the structure is high? But this would be okay for reusable rockets right? Then even with spaceX's reusable rockets why is the launch cost still very high?

 

[mfb]

The cost to build the rocket is most of the launch cost. Development is a big part, and launch site operations are important as well.

SpaceX has the cheapest rocket in its size class, they don’t have an incentive to make it significantly cheaper for customers. They can recover development costs faster if they just give a small discount.

It has been estimated that SpaceX spends about 30-35 millions for a new first stage, refurbishing the first one took nearly 15 millions so they saved about 15-20 millions there. That number should be larger for the following reuses. If block 5 flies with just inspections and a refurbishment every 10 flights as promised they will save nearly the full cost of the first stage. Fairing reuse would save another 5 millions or so. That leaves the expendable second stage, launch site operations and overall keeping the company running. They will need a lot of money for development of the fully reusable BFR - there fuel costs could become relevant simply because everything else is supposed to become so cheap.

 

[chandrahas]

Thanks I think I understand. But by refurbishing what is being done exactly, because they don't have any heat shield. Is it the engines and the surface material?

 

[mfb]

The boosters have some sort of heat shield at the bottom. I don’t know what exactly they plan to do, I’m not even sure SpaceX knows how their rockets will look like after 10 flights. It is a new technology, they will find something that works while flying Block 5.

 

[Clark Magnuson]

I was loaned out to Rocket Research a couple of times; Midgetman Missile proposal and ArcJet development.
They had high overhead, but the ceilings were not as high as at the Boeing development center.

 

[Tracey3]

I had an internship with a major missile and satellite engineering company. My mentor mentioned to me that about 10-15% of their cost comes just from trying to meet all the regulations and what he referred to as 'bureaucratic nonsense'.

 

[sandy stone]

One person's bureaucratic nonsense is another person's public safety and environmental protection.

 

[OldYat47]

Anything hand made with dozens, possibly hundreds, of custom machined parts is going to be very costly. And that doesn't even begin to address testing and development. They would be cheaper if they were standardized and mass produced, but I don't see that as a practical approach with current technology and rates of improvements.

 

[mfb]

SpaceX tries to go in that direction. They built 500 Merlin engines so far, for example.

 

[glappkaeft]

I like the answer given by knowledgeable people in the old Usenet space related news groups. Since cash is not used anywhere in the design of rockets 100% of the money is spent on salaries (removing or ignoring profit/losses for the purpose of the calculation). If you get another number that depends only on how you are accounting costs.

 

[mfb]

Money always goes to people. This is independent of the type of payment. Anything not human does not need, use, or get money. It is not just salaries, however. You also have to pay people owning the raw resources, owning the land or the facilities and so on, and these things are not salaries.