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Does anyone have a good summary of Starship and what the goal is? I still don't quite understand why they didn't just iterate on the Falcon design and what nece

by geokon 6y ago

Does anyone have a good summary of Starship and what the goal is? I still don't quite understand why they didn't just iterate on the Falcon design and what necessitates a "full stack" clean slate approach. Why do they need to develop new engine for instance? Like.. why couldn't they develop new engine and upgrade the Falcons with them? Once Starship is working consistently, will the Falcons become obsolete b/c Starships will become much more reusable?

tomp 6y ago
Different engines (Falcon is Kerosene, Starship is Methane), fully reusable (even the upper "orbital" stage), bigger and simpler (Elon said a while back that designing Falson Heavy (1 upper stage, 3x lower stage) was pretty much as difficult as designing a whole new rocket) and therefore better (in rockets, the bigger the rocket, the better - as the ratio between "framework" (computers, engines, metal exterior) and "fuel+payload" goes down so you can lift more).
martythemaniak 6y ago
Starship is a pretty radical redesign with the main goal being reusability. Everything about it is with reusability and and thus scale in mind. A new engine was needed because while the Merlin is a great engine, it could never be reused the thousands of times Raptor is designed to be reused. You can think of engine design as the simultaneous, interdependent optimization across 10+ dimensions, but as an example of one of dimensions - Raptor uses Methane (rather than Kerosene) because it burns cleaner (does not leave residue) and can be manufactured on Mars more easily. Here's an in-depth video about Raptor: https://www.youtube.com/watch?v=LbH1ZDImaI8 https://www.youtube.com/watch?v=LbH1ZDImaI8 The rest of the rocket is similar, in that it is done with manufacturability, reusability and scale in mind. The Falcon design could never stretch to these demands.
bryanlarsen 6y ago
Musk figures we need to ship a million tonnes of cargo to Mars colonize it. An upgraded Falcon would cost too much. The Starship design decisions all come from that goal. - big - rapidly and fully reusable - fuel that can be synthesized on Mars
babesh 6y ago
Their goal is establishing a Mars colony (1,000,000 humans). That necessitates a fully reusable rocket that can get humans to Mars and back. That means being able to enter Mars atmosphere at high speed and landing on Mars. That also means using a fuel that they can manufacture on Mars to return to Earth. - Falcon doesn't have a reusable second stage. Starship's second stage is reusable. Starship should be more cost efficient because of this. - Falcon doesn't have the capacity to carry enough humans and cargo to Mars. It is a trip that can take upwards of half a year. Starship can supposedly carry 100 people and 100 tons of cargo. Falcon with Crew Dragon can only carry 7 people a few days. - Starship is designed to be able to enter Mars atmosphere. Its skin is stainless steel and some heat shielding. The stainless steel can survive much higher temperatures which means less heat shielding. Falcon is aluminum and would require more heat shielding. - Falcon has fuel tanks for its Merlin engines that use rocket fuel (RP-1?) and oxygen. The tanks are a specific size for the burn ratios. The rocket fuel can't be readily made on Mars and its mass makes it infeasible to carry enough fuel for a return. Starship's engines (Raptor) use methane and oxygen. Methane can be readily made on Mars. Changing Falcon from Merlin to Raptor engines would mean redesigning the tanks to have different sizes. Given all this, it makes more sense to design a new rocket than trying to redesign the existing one.
- imglorp 6y ago
  I like to point out that a Boring Co. tunnel boring machine will fit inside a Starship. 14 feet vs 30 feet. Coincidence?
  - babesh 6y ago
    Oh. I guess they are living underground.
    - baking 6y ago
      And traveling via hyper-loops because the whole vacuum tube collapse thing won't be an issue.
      - 6y ago
mabbo 6y ago
> Why do they need to develop new engine for instance? "Need" is interesting. There are two key goals with the Raptor engine. #1- Switch to Methane burning. Methane is available much more easily everywhere in the solar system- Mars especially. So we can make fuel wherever we are instead of bringing it. #2- Make it much more resilient to re-use. Those Merlin engines are great, but they need a lot of work to get them ready to go again. Lots of inspection. Raptor is a Full-flow staged combustion engine[0]. Everyday Astronaut does a great write-up (and video) on the topic[1]. > why they didn't just iterate on the Falcon design and what necessitates a "full stack" clean slate approach Falcon is big, but it isn't huge. It's got a 3.7m diameter. Starship has a 9m diamater, almost 2 and a half times wider (meaning more than 5 times larger circumference). When you scale up that much, you're basically starting over. This size increase also means Starship should be able to lift something like 6 times more to orbit. And because it's so huge, it won't need a booster to launch itself from Mars or the Moon. Materials also matter. Falcon is made of carbon fiber: carbon fiber is expensive and hard to work with. It's slow. Iteration is slow. If you want to blow up 1 rocket per month in testing, that's going to get expensive and take a lot of work to make happen, especially given the larger size. Steel, on the other hand, is cheap and fast. So Starship is based on steel. Starship is also fully reusable. Falcon 9 isn't- the second stage is expended. They looked into how they might bring those back, but it just wasn't worth the R&D effort. When it's all done, Starship is going to be a fully-reusable system that is cheap to build, cheap/easy to operate, can be refueled easily, anywhere (like Mars), can launch itself from the Moon or Mars without a booster. It will be cheaper to launch per kg than any other launch system out there by probably an order of magnitude. It will dominate the competition and likely claim a monopoly on the private launch market until someone gets their shit together and competes. [0]https://en.wikipedia.org/wiki/Staged_combustion_cycle#Full-flow_staged_combustion_cycle https://en.wikipedia.org/wiki/Staged_combustion_cycle#Full-f... [1]https://everydayastronaut.com/raptor-engine/ https://everydayastronaut.com/raptor-engine/
- bryanlarsen 6y ago
  > Falcon is made of carbon fiber Falcon's walls and domes are made of aluminum-lithium alloy. They do have a tiny bit of carbon fiber; for example they have composite overwrapped pressure vessels (COPV) containing helium for pressurization.

by geokon 6y ago

tomp 6y ago

Different engines (Falcon is Kerosene, Starship is Methane), fully reusable (even the upper "orbital" stage), bigger and simpler (Elon said a while back that designing Falson Heavy (1 upper stage, 3x lower stage) was pretty much as difficult as designing a whole new rocket) and therefore better (in rockets, the bigger the rocket, the better - as the ratio between "framework" (computers, engines, metal exterior) and "fuel+payload" goes down so you can lift more).

martythemaniak 6y ago

Starship is a pretty radical redesign with the main goal being reusability. Everything about it is with reusability and and thus scale in mind. A new engine was needed because while the Merlin is a great engine, it could never be reused the thousands of times Raptor is designed to be reused. You can think of engine design as the simultaneous, interdependent optimization across 10+ dimensions, but as an example of one of dimensions - Raptor uses Methane (rather than Kerosene) because it burns cleaner (does not leave residue) and can be manufactured on Mars more easily. Here's an in-depth video about Raptor: https://www.youtube.com/watch?v=LbH1ZDImaI8 https://www.youtube.com/watch?v=LbH1ZDImaI8 The rest of the rocket is similar, in that it is done with manufacturability, reusability and scale in mind. The Falcon design could never stretch to these demands.

bryanlarsen 6y ago

Musk figures we need to ship a million tonnes of cargo to Mars colonize it. An upgraded Falcon would cost too much. The Starship design decisions all come from that goal. - big - rapidly and fully reusable - fuel that can be synthesized on Mars

babesh 6y ago

Their goal is establishing a Mars colony (1,000,000 humans). That necessitates a fully reusable rocket that can get humans to Mars and back. That means being able to enter Mars atmosphere at high speed and landing on Mars. That also means using a fuel that they can manufacture on Mars to return to Earth. - Falcon doesn't have a reusable second stage. Starship's second stage is reusable. Starship should be more cost efficient because of this. - Falcon doesn't have the capacity to carry enough humans and cargo to Mars. It is a trip that can take upwards of half a year. Starship can supposedly carry 100 people and 100 tons of cargo. Falcon with Crew Dragon can only carry 7 people a few days. - Starship is designed to be able to enter Mars atmosphere. Its skin is stainless steel and some heat shielding. The stainless steel can survive much higher temperatures which means less heat shielding. Falcon is aluminum and would require more heat shielding. - Falcon has fuel tanks for its Merlin engines that use rocket fuel (RP-1?) and oxygen. The tanks are a specific size for the burn ratios. The rocket fuel can't be readily made on Mars and its mass makes it infeasible to carry enough fuel for a return. Starship's engines (Raptor) use methane and oxygen. Methane can be readily made on Mars. Changing Falcon from Merlin to Raptor engines would mean redesigning the tanks to have different sizes. Given all this, it makes more sense to design a new rocket than trying to redesign the existing one.

imglorp 6y ago
I like to point out that a Boring Co. tunnel boring machine will fit inside a Starship. 14 feet vs 30 feet. Coincidence?
- babesh 6y ago
  Oh. I guess they are living underground.
  - baking 6y ago
    And traveling via hyper-loops because the whole vacuum tube collapse thing won't be an issue.
    - 6y ago

mabbo 6y ago

> Why do they need to develop new engine for instance? "Need" is interesting. There are two key goals with the Raptor engine. #1- Switch to Methane burning. Methane is available much more easily everywhere in the solar system- Mars especially. So we can make fuel wherever we are instead of bringing it. #2- Make it much more resilient to re-use. Those Merlin engines are great, but they need a lot of work to get them ready to go again. Lots of inspection. Raptor is a Full-flow staged combustion engine[0]. Everyday Astronaut does a great write-up (and video) on the topic[1]. > why they didn't just iterate on the Falcon design and what necessitates a "full stack" clean slate approach Falcon is big, but it isn't huge. It's got a 3.7m diameter. Starship has a 9m diamater, almost 2 and a half times wider (meaning more than 5 times larger circumference). When you scale up that much, you're basically starting over. This size increase also means Starship should be able to lift something like 6 times more to orbit. And because it's so huge, it won't need a booster to launch itself from Mars or the Moon. Materials also matter. Falcon is made of carbon fiber: carbon fiber is expensive and hard to work with. It's slow. Iteration is slow. If you want to blow up 1 rocket per month in testing, that's going to get expensive and take a lot of work to make happen, especially given the larger size. Steel, on the other hand, is cheap and fast. So Starship is based on steel. Starship is also fully reusable. Falcon 9 isn't- the second stage is expended. They looked into how they might bring those back, but it just wasn't worth the R&D effort. When it's all done, Starship is going to be a fully-reusable system that is cheap to build, cheap/easy to operate, can be refueled easily, anywhere (like Mars), can launch itself from the Moon or Mars without a booster. It will be cheaper to launch per kg than any other launch system out there by probably an order of magnitude. It will dominate the competition and likely claim a monopoly on the private launch market until someone gets their shit together and competes. [0]https://en.wikipedia.org/wiki/Staged_combustion_cycle#Full-flow_staged_combustion_cycle https://en.wikipedia.org/wiki/Staged_combustion_cycle#Full-f... [1]https://everydayastronaut.com/raptor-engine/ https://everydayastronaut.com/raptor-engine/

bryanlarsen 6y ago
> Falcon is made of carbon fiber Falcon's walls and domes are made of aluminum-lithium alloy. They do have a tiny bit of carbon fiber; for example they have composite overwrapped pressure vessels (COPV) containing helium for pressurization.