Introduction:

Tim Dodd, the Everyday Astronaut, welcomes viewers to Starbase, Texas. This SpaceX facility serves as the hub for the company’s Mars-bound rocket, Starship. Tim promises a behind-the-scenes look into areas previously undisclosed to the public.

Special Guest:

Elon Musk is introduced as the ultimate tour guide who will provide insights into the rocket’s development. The footage from their extensive conversation will be divided into three parts: two at the Starbase factory and one at the launch pad.

Content Warning:

Tim forewarns that the tour will include advanced aerospace concepts that might be complex on a first listen. To help the audience understand, he refers to supplementary informational videos available on his channel.

Mention of Soviet Rocket Engines:

Soviet rocket engines are frequently mentioned in the conversation. Tim suggests this could be due to his new Soyuz shirt or his upcoming video on the history of Soviet rocket engines.

Additional Resources:

Tim mentions that the video is broken into sections, with links in the description for easier navigation. He also offers a map, courtesy of Ring Watchers on Twitter, and an article summarizing the key points of the conversation.

Preparation for the Tour:

Before the tour begins, Tim and Elon discuss the multiple cameras being used to record the event, humorously referring to it as “camera envy.”

The segment serves as an introduction for an in-depth look at SpaceX’s Starship program, offering viewers the promise of technical insights and exclusive footage.

Launch System Complexity:

Elon Musk discusses the final stages of the launch system’s development, emphasizing its complexity. According to him, the tower and the “chopstick arms” designed to catch the rocket are as complex as any of the rocket’s individual stages. Musk claims it’s easier to produce boosters and ships than to set up the entire launch site.

Underrated Importance of Manufacturing:

Both speakers highlight that manufacturing is often an overlooked aspect of rocket science. Musk argues that design is overrated and that significantly more work goes into manufacturing. For instance, the effort put into designing the Raptor engine’s manufacturing system exceeds the engine’s own design by 10 to 100 times.

Cost-Effectiveness and Thrust:

Musk emphasizes the need for cost-effectiveness, particularly focusing on the cost per ton of thrust and cost per ton to orbit as key metrics. He argues that humanity’s ability to become a space-faring civilization hinges on optimizing these costs.

Design Challenges:

Musk counters the notion that design is the hardest part of rocket engineering. He acknowledges the advanced state of Russian rocket engine designs, stating that his company’s advancements are minor by comparison. The challenge, according to him, lies in mass-producing engines like the Raptor at under $1,000 per ton of thrust.

Engineering Details:

There’s an examination of various engineering factors like thrust-to-weight ratio and nozzle exit to thrust ratio. Musk mentions that the current version of their rocket has 29 engines. He also touches on the sensory overload caused by the various alerts and beeps during operations.

Mass and Weight Considerations:

The speakers discuss the dry mass of rocket components, aiming to keep it under 200 tons. Musk provides an approximate breakdown of the components’ weights, mentioning that everything is currently too heavy, even the avionics. He notes that the grid fins are electrically powered and require batteries that are energy-optimized rather than power-optimized.

Key Takeaway:

The conversation emphasizes that the complexity and cost-efficiency of the manufacturing process are crucial for the future of space exploration, challenging the conventional wisdom that prioritizes design.

Reducing Battery Mass:

Elon Musk suggests that there’s significant potential to reduce the battery mass in rockets, possibly by a factor of 10. This reduction is crucial in improving the rocket’s efficiency and cost-effectiveness.

Propellant Composition:

Musk explains the propellant in the rocket booster is designed to contain 3,600 tons, of which almost 80% is liquid oxygen. The rationale behind this composition is that oxygen is denser and cheaper than alternative options. This balances cost and payload capacity effectively.

OF Ratio and Heat Concerns:

Musk and the other speaker discuss the Oxidizer-to-Fuel (OF) ratio in rocket engines. Going too close to a stoichiometric OF ratio could potentially melt the rocket engine due to high heat. Thus, there’s a trade-off when deciding this ratio, as it affects the rocket’s performance.

Design Simplification:

Musk presents a five-step process to enhance rocket design. The first step is to reassess and simplify requirements, regardless of who initially set them. The second step is to remove unnecessary parts or processes, with Musk highlighting that not folding the grid fins was a beneficial design decision.

Accountability in Requirements:

He emphasizes that every requirement should be accompanied by the name of the person who proposed it. This ensures accountability and prevents blindly following outdated or irrelevant guidelines.

Optimization vs Deletion:

Musk warns against the common engineering mistake of optimizing components that should be eliminated altogether. He suggests that if you aren’t deleting at least 10% of parts or processes and then adding some back in, you’re not scrutinizing enough.

The Cost of Propellant Choices:

Towards the end, Musk elaborates on the economic inefficiency of using certain chemicals like nitrogen tetroxide and monomethylhydrazine as propellants. These chemicals are not just expensive but also hazardous, raising both cost and safety concerns.

General Philosophy:

Musk articulates that creating a fully reusable rocket is the ‘holy grail’ of rocketry, requiring tight margins and rigorous design processes. The goal is to get the maximum payload to orbit while minimizing costs and complexity.

Four Steps for Operational Efficiency:

Elon Musk talks about a four-step process to improve operational efficiency. The steps include 1) simplification, 2) optimization, 3) acceleration, and 4) automation. He emphasizes that acceleration should not be pursued until the other three steps are adequately managed, cautioning against “digging your own grave” faster if things are not in order.

Personal Experience with Mistakes:

Musk admits to personally making mistakes by not following these steps in the correct order. He has had to revisit them multiple times, particularly with Tesla’s Model 3 production.

Case Study: Model 3 Battery Pack:

He cites an example related to the production of the Tesla Model 3’s battery pack. At one point, the production was bottlenecked due to issues with fiberglass mats between the battery and the vehicle’s floor pan. Musk initially tried to improve the automation, attempting to make robots perform tasks more efficiently.

Lesson on Over-Engineering:

Musk explains that in his attempts to fix the issues, he realized that he was over-engineering the solution. Instead of applying glue over the entire battery pack, he found that just small dabs were sufficient to hold the fiberglass mats in place.

Inter-Departmental Confusion:

When Musk finally questioned the necessity of the mats, he received contradictory answers from different departments. The battery team said the mats were for noise and vibration, while the noise and vibration team thought they were for fire safety. This episode highlights the challenges of cross-functional communication and the need for clarity in large organizations.

Final Takeaway:

Musk’s insights shed light on the importance of systematically improving operations while avoiding common pitfalls. His experience offers a roadmap for tackling complex production challenges, including the importance of inter-departmental communication and not over-complicating solutions.

Questioning the Necessity of Components:

Elon Musk continues discussing the dilemma he faced with the fiberglass mats in Tesla Model 3’s production. After conducting audio tests with and without the mats, he found that they made no discernible difference in the car’s performance. Consequently, he decided to remove them, saving costs and complexity.

Issues with In-Process Testing:

Musk highlights a common mistake in production lines: excessive in-process testing. Initially, this testing is crucial to identify where problems are occurring. However, failing to remove these tests after diagnosing issues can bottleneck the production line, leading to false positives and negatives. He suggests moving most testing to the end-of-line to improve efficiency.

Significance of Accurate Testing Methods:

One crucial aspect of battery production is ensuring resistance to water ingress. Musk shares that Tesla initially used the wrong method for testing this feature. They were pressurizing the battery pack, leading to frequent test failures. The appropriate test should have been drawing a vacuum on the pack, highlighting the importance of using accurate testing methods.

Impact of Real-world Use Cases:

Elon emphasizes that the water resistance of Tesla’s battery pack has real-world implications. He references an incident where a Tesla Model S was driven through a flooded tunnel, underscoring the battery pack’s importance in such extreme conditions.

Importance of Adaptability and Flexibility:

Throughout his discussion, Musk reiterates the importance of being adaptable and flexible when solving production issues. He likens his experiences to being caught in a “Dilbert cartoon,” illustrating the absurdity and complexity of the challenges he often faces.

In summary, Musk’s account provides valuable insights into the intricacies of manufacturing, the importance of correct testing procedures, and the need for flexibility in problem-solving.

Design and Functionality of Grid Fins:

Elon Musk and the other speakers discuss the design of a heavy grid fin that is estimated to weigh around three tons. The serrated teeth of the fin are designed to improve its effectiveness in transonic and subsonic flight regimes. The fin is motorized and can be adjusted to correct the spacecraft’s trajectory during descent.

Iterative Design Philosophy:

Musk emphasizes the importance of an iterative design approach to aerospace engineering. He notes that the fin design will eventually be optimized to reduce weight but emphasizes that the first step is to make sure it functions as needed. This approach reflects a broader philosophy of creating a “minimum viable product,” which is then iteratively improved.

Learning from Failures:

Discussing the failed tests of earlier Starship models, Musk reveals that the reasons for these failures were not on the pre-existing risk lists, underscoring the importance of learning from practical tests. He suggests that dealing with “unknown unknowns” is a key part of the development process.

Engineering Versatility:

The grid fin’s motor will react onto the fuel dome of the spacecraft and is based on Tesla Model 3 motors, demonstrating the inter-disciplinary use of technology developed for other products.

Removing Unnecessary Features:

In terms of broader design, there is discussion about simplifying systems. Musk hints at the potential removal of cold or hot gas thrusters in future designs to cut weight and complexity. The aim is to first make systems functional and then optimize them.

Complexity and Unknown Risks:

Musk highlights the challenges of dealing with multiple evolving technologies simultaneously. He stresses the need to identify and understand new risks as they appear during the development process.

This segment provides valuable insights into the complexities of aerospace engineering, the importance of an iterative design process, and the need to adapt to unexpected challenges.

Raptor Version 2 Development:

Elon Musk reveals that parts of the Raptor Version 2 engine have already been made, including the thrust chamber assembly. The design of the pumps is also near completion. Testing of the first Raptor 2 is anticipated to occur in about a month.

Production Locations:

Elon Musk specifies that volume production of the Raptor engine will happen in McGregor, while the California Factory will focus on development engines and the Raptor Vacuum Ocean version.

Performance Metrics:

The new version aims for a thrust of 230 tons at a bar of 300. Even though the actual bar value might be around 298, Elon Musk shows an interest in pushing it to 300.

Thrust to ISP Trade-Off:

The Version 2 Raptor is designed to prioritize thrust over specific impulse (ISP). The extra thrust will come at a cost of losing two to three seconds of ISP, but this loss is deemed acceptable, especially for the first stage of the rocket.

Thrust Measurement in Tons:

When asked about measuring thrust in tons, Musk explains that it simplifies the mental math when dealing with rockets, despite not being a technically scientific measure.

Significance of Thrust-to-Weight Ratio:

The discussion touches on the critical nature of the thrust-to-weight ratio. Any ratio below one is considered worthless, and even a slight increase in this ratio makes a significant difference in the rocket’s performance.

Unit Preferences:

Elon Musk expresses a strong preference for using tons and bars as units for measuring thrust and pressure, respectively, in rocket engineering. He argues that these units make it easier to perform mental calculations and thus enhance intuitive understanding. He dismisses the use of Newtons and Pascals as “annoying” and “absurd.”

Engineering Philosophy:

Musk advocates for everyone involved in a project to understand the system at a high level, essentially being a “chief engineer.” This holistic understanding allows for better decision-making, particularly when it comes to optimization. For example, Musk mentions how focusing too much on engine mass while ignoring propellant residuals can lead to inefficiencies.

Propellant Residuals:

Musk points out a specific inefficiency in Falcon 9, which lands with about a ton of unused fuel. He sees this as problematic, given the extensive effort put into reducing engine mass.

Stage Separation Mechanism:

Musk discusses an interesting stage separation technique used in Starlink satellite launches. The integrated stack is rotated before main engine cut-off, relying on the varying inertia of components to facilitate natural separation. This eliminates the need for a separate mechanism for stage separation, thereby simplifying the system.

Unique Satellite Deployment:

Elon Musk describes a unique approach to satellite deployment, comparing it to tossing 60 satellites off a rocket like a bundle of hay. This unconventional technique uses rods similar to hay bales for holding satellites, which are then simply “flung” into space.

Complex Thruster Mechanisms:

The talk delves into intricate details of thruster mechanisms, focusing on attitude control thrusters and reaction control thrusters. Instead of using separate hot or cold gas thruster systems, SpaceX employs the main engines to initiate rotation of the rocket stack, eliminating the need for auxiliary systems.

Efficient Use of Gas:

Musk outlines the utility of ullage gas, which is basically hot gaseous oxygen and methane. These gases offer decent thrust in vacuum conditions and are already present in the rocket’s main tanks, obviating the need for separate storage.

Pressure Considerations:

Musk compares the pressure in the main tanks to that of other in-space thrusters, like the Draco thrusters. The pressures are surprisingly similar, eliminating the need for additional storage systems at higher pressures.

Lunar Landing Considerations:

When it comes to landing on the Moon, Musk discusses the challenges of choosing between using the main engines or additional thrusters placed higher on the spacecraft. He raises the concern that landing with the main engines might “dig a ditch” in the lunar surface, which is not desirable.

Design Evolution:

The conversation indicates that SpaceX’s designs, even for landing on the Moon, are not set in stone and are likely to evolve. Musk mentions the need for additional tests to verify whether using main engines for lunar landing would be viable without creating problematic surface depressions.

Questioning Requirements:

Throughout the talk, Musk emphasizes the need to continually reassess and question existing engineering assumptions and requirements. For instance, he suggests that a significant amount of ship maneuvering could be achieved using already existing hot gas, making other systems redundant.

Engine Variability in Different Atmospheres:

Elon Musk discusses the use of different engines for rockets depending on whether they are in an atmosphere or in a vacuum. He notes that vacuum engines don’t gimbal, meaning they lack the ability to pivot for steering. In low-disturbance environments like the moon, which lacks an atmosphere, rockets require less control authority.

Engine Configuration Choices:

The conversation revolves around the optimal number and type of engines for varying circumstances. While it’s possible to land a rocket with just three engines through differential throttling, a failure in any of these would be catastrophic. Therefore, Musk seems to lean towards keeping the current engine configuration or even adding one in the middle for better control.

Optimization Goals:

The extent of optimization depends on the objectives and constraints, including how many units are going to be produced. The implication is that the design would vary if only one unit is being made compared to multiple units.

Regulatory and Communication Considerations:

Musk hints that some information may be sensitive and may not be allowed for public sharing due to ITAR (International Traffic in Arms Regulations) and communication restrictions.

Wrap-Up and Acknowledgments:

The host, Tim Dodd, the Everyday Astronaut, thanks Elon Musk and SpaceX teams for the discussion. He also thanks his Patreon supporters and plugs his merchandise. This conversation was part of a larger discussion, with more content promised for the future.