Introduction of Tour:

The discussion is set in Starbase, Texas, where Tim Dodd, the Everyday Astronaut, serves as the host. The main speaker is Elon Musk, who is referred to as the ‘Ultimate Tour Guide’. The tour focuses on visiting the high bay, where starships are assembled, and the new mega bay under construction. The purpose is to delve into SpaceX’s plans to accelerate the rocket production process.

Mega Bay Construction:

Elon Musk notes that the construction of the new mega bay is progressing well and should be completed in about a month. This structure will be taller by about 30 to 40 feet compared to the existing high bay.

Importance of Space:

Musk emphasizes that for SpaceX’s objectives, the width and length of the bay are more critical than its height. This is because more space is required for constructing multiple ships and boosters simultaneously.

High Bay vs. Mega Bay:

The existing high bay can accommodate around two or three workstations. In contrast, the mega bay will potentially feature at least 10 workstations, making it significantly more productive. The width and length are strategically designed to facilitate a higher production rate.

Scaling Production:

Elon Musk explains that while the high bay is adequate for low production rates, scaling up the production necessitates more workstations. The mega bay is designed specifically to meet this requirement, allowing SpaceX to operate at higher production rates.

Utilizing Ullage Gas:

Elon Musk discusses an innovative shift in how SpaceX approaches attitude control for their rockets. Instead of using separate attitude control thrusters, they are now using ullage gas for both attitude and reaction control. This change is largely due to the minimal impulse needed for attitude control once a rocket is in orbit or in a vacuum.

Efficiency over Previous Designs:

In earlier designs, SpaceX used a separate cold gas attitude control system with nitrogen bottles. Musk pointed out that this was not efficient, as ullage gas would be vented anyway. The ullage gas can also be used for small changes in velocity (delta V) once the rocket is in orbit, making it a more multifunctional resource.

Concerns about Maneuvers:

The host questioned whether the ullage gas system would be practical for more complex maneuvers, like those needed during docking. Musk explained that there is generally more than enough pressure in the fuel and oxygen tanks, which are autogenously pressurized, to handle these maneuvers.

Pressure Stabilization and Venting:

Musk elaborates that the main tanks of the rocket need to be vented down to just above atmospheric pressure for structural stability during re-entry. Since the tanks would have to be vented anyway, using the ullage gas for attitude control is deemed to be more efficient. Separate tanks for this purpose would be redundant.

Cost and Mass Optimization:

One of the most significant improvements made to the rocket design is using ullage gas for attitude control, leading to both mass and cost savings. Musk mentions that this was a realization that occurred to him “in real time” and represents a significant optimization over older designs.

Unique Needs of SpaceX’s Rockets:

The host mentions that traditional spacecraft don’t often have the same considerations as SpaceX rockets, which spend a short period in high-thrust burns and then require fine control. Musk agreed that utilizing ullage gas for this purpose is an obvious move in retrospect and significantly more efficient.

Introduction of Joe Pietrzalka:

Elon Musk introduces Joe Pietrzalka as the head of Booster Engineering. The discussion that follows is a detailed explanation of the engineering advancements and challenges related to the rocket boosters being developed by the company.

Improvements in Booster 7:

Booster 7, which is currently at the pad, shows significant improvements over its predecessors. Notably, the team has simplified the design, upgraded grid fins, and added new aerodynamic features, such as chines or strakes, to improve reentry performance. The booster will come in at a lower velocity and with higher precision when caught by the tower, enhancing its reusability.

Design and Angle of Chines:

A query is made about why the chines are not placed 180 degrees opposite each other; instead, they are about 120 degrees apart. Joe explains that the chines help pressurize the rest of the rocket cylinder, thus providing more net drag on that section. Their unique positioning allows the booster to pitch up higher, which is important since the booster is bottom-heavy due to the engines.

Integrated Pressure Profile:

Elon adds to Joe’s explanation by focusing on the “integrated pressure profile on the base.” The positioning of the chines helps to catch more of the air that would otherwise escape around the cylinder. This technique allows for slightly less cross-sectional area but yields more integrated pressure at the base of the rocket, leading to enhanced control during reentry.

Iterative Development:

Both Elon and Joe acknowledge that the chines are still in a primitive stage and are likely to evolve significantly in future iterations. They are also designed to serve dual purposes; aside from aerodynamics, they also act as a cover for the Composite Overwrapped Pressure Vessels (COPVs), adding another layer of utility to their inclusion in the design.

This discussion underscores the complexity and ongoing development involved in improving rocket booster technology for better performance and reusability.

Booster Development:

Elon Musk and the head of Booster Engineering, Joe Pietrzalka, discuss the iterative process of booster development. Booster 7, the latest version, features various upgrades for better reentry performance, including upgraded grid fins and chines (or strakes) on its sides. The purpose of these features is to reduce velocity and improve precision during reentry.

Chine Design:

Both speakers elaborate on the design of chines, which are placed at approximately 120-degree intervals around the rocket. The chines serve to increase the net drag on the booster, enabling greater control. Elon Musk adds that the chines’ orientation helps in capturing more air around the booster, enhancing the integrated pressure at its base.

Grid Fin Versus Traditional Stabilizers:

The discussion also covers the rationale behind continuing with grid fins instead of traditional stabilizers like wings. According to Musk, grid fins offer more consistent performance across different Mach regimes. They are also easier to actuate than wings, requiring less power to adjust their orientation.

Optimization and Future Plans:

Musk acknowledges that their current designs are not necessarily optimal but are functional. The focus is on achieving orbit, utilizing previous learnings from the Falcon 9 rocket. Musk hints that they could reduce the number of grid fins needed for stability, suggesting that two or three might be sufficient in future iterations.

Dynamic Stability Concerns:

The conversation also delves into the issue of dynamic stability. Small asymmetries in the rocket’s structure or any positional errors can lead to instability, making control surfaces like grid fins essential. Musk indicates that they’ve already reduced the size of the grid fins to make them lighter, and further reductions are being considered.

Trade-offs and Iterations:

Both speakers highlight the trade-offs involved in design choices. While grid fins might not be as efficient as wings in some aspects, their benefits in terms of actuator power and consistent performance across different speeds make them the more viable option for now. The design has undergone numerous iterations, and further changes are expected as they continue to optimize for various operational parameters.

Launch Preparations:

Elon Musk and the team discuss the rapid developments concerning Booster 8 and Booster 7, as well as Ship 24. These components are in the final stages of preparation for SpaceX’s first orbital launch, aimed to be paired with Starlink satellites. Ship 24 is noted to be more refined than its predecessor, S20.

Starlink Deployment Mechanism:

The Starlink satellites are housed in a racking system within the fairing of the ship, humorously likened to a PEZ dispenser by Musk. The rectangular Starlink satellites are stacked, allowing for efficient use of space. The system only needs a small door for deployment, aiding in pressure stabilization within the fairing. This design choice is contrasted against potential future designs that may require much larger hinged doors for bigger cargo.

Technical Complexities and Risks:

The team acknowledges inherent complexities and risks in their deployment system. Although inspired by industrial pallet stacking technology, the system has to work reliably in both Earth’s gravity and the weightlessness of space. Any jamming or malfunction during the satellite deployment would be embarrassing and potentially catastrophic. Additionally, they discuss the current plan for the next launch to be fully orbital, dismissing earlier ideas about it being suborbital.

Risk Mitigation:

Musk does not express high confidence that the first flight will reach orbit successfully, enumerating various possible points of failure including stage separation, booster issues, or the ship failing to start. He indicates that even if the ship does reach orbit, a safe return is not guaranteed. To mitigate risks, the ship’s re-entry is planned over the Pacific Ocean, to avoid endangering populated areas.

Future Orbital Launch Plans:

Despite previous talks about suborbital tests, the team reaffirms that their focus is on achieving full orbital launches. The difference in velocity between suborbital and orbital is described as “hilariously small,” making the extra loop around Earth unnecessary. Nonetheless, the team is aware of the high-risk nature of this endeavor.

Heat Shield Design:

Elon Musk discusses the design of the heat shield tiles, addressing questions about why they aren’t designed like dragon scales or shingles with overlapping layers. Musk explains that multiple design approaches could work but highlights the tiles’ ability to expand when hot, thus tightening the gaps between them.

Heat Flow Dynamics:

Both Musk and another speaker clarify that the heat doesn’t flow directly into the gaps but flows around the vehicle. This happens because the vehicle re-enters the Earth’s atmosphere at an angle similar to the Space Shuttle, at approximately 60 to 70 degrees.

Tile Expansion and Gap Closure:

The design assumes that as the tiles heat up during re-entry, they will expand and close the gaps. Musk suggests that heat is unlikely to flow down through these gaps, making an overlapping, shingled design unnecessary. He does, however, acknowledge the possibility of being wrong about this aspect of the design.

Reusability and Peak Heat Load:

For a reusable spacecraft, the focus is on minimizing the peak heat load, which would determine if the tiles melt. Musk emphasizes that the design aims to strike a balance between generating lift and ensuring the heat shield remains intact by managing peak heat loads efficiently.

Reusable Heat Shield Tiles:

Elon Musk talks about the delicate balance needed in designing heat shield tiles for reusable spacecraft. Melting the tiles would render them unsuitable for reuse, so the goal is to minimize peak heat loads during atmospheric re-entry.

Atmospheric Considerations:

He discusses how the spacecraft aims to slow down as much as possible in the thin upper atmosphere to reduce peak heating. Doing so involves considering various factors like atmospheric density and velocity. The spacecraft should avoid high speeds in dense air to mitigate heat generation.

Learning from Initial Entries:

Musk anticipates that the first re-entry will provide valuable data. If unexpected heating occurs in some areas, the spacecraft would fail upon re-entry, providing lessons for future missions.

Transition to Orbital Flights:

Addressing the shift from suborbital to orbital missions, Musk says they’ve learned what they needed from suborbital flights. While these were visually exciting, the focus now is on advancing to orbital flights for more meaningful data collection and challenges.

Starship’s Thrust-to-Weight Ratio:

Elon Musk discusses the high thrust-to-weight ratio of SpaceX’s Starship, around 1.4 to 1.5. He points out that Starship will lift off the pad quickly, contrasting with other rocket designs. The thrust-to-weight ratio is particularly important for reusable rockets, like Starship, because a higher ratio makes the propellant more useful. The ratio of thrust to weight below one doesn’t efficiently utilize the propellant, which is significant since the cost of the propellant represents the most significant expense for reusable rockets.

Optimizing Cost Per Ton:

Musk emphasizes the importance of optimizing for the “fully considered cost per ton to orbit” when developing rocket technology. Unlike other metrics like mass ratio or ISP, the cost per ton to orbit is a straightforward measure of a rocket’s economic efficiency. Any technology is relevant only to the extent that it reduces this cost.

Challenges for Mars and Moon Missions:

Elon Musk also elaborates on the astronomical costs associated with current Mars missions. Currently, the cost to deliver a ton to Mars is about a billion dollars. Musk aspires to reduce this cost to under $100,000 a ton, representing an improvement factor of 10,000. This is vital for achieving the goal of establishing a self-sustaining city on Mars.

Design Challenges and Iteration:

Musk openly discusses some of the design challenges they face, specifically with the positioning and size of the forward flaps on Starship. He considers them suboptimal and even suggests that they might eventually be eliminated altogether, like in the design of the Space Shuttle. This highlights SpaceX’s philosophy of rapid iteration and improvement.

Center of Mass and Pressure:

Towards the end of the discussion, Musk talks about the balancing act between the center of mass and the center of pressure for the vehicle. This equilibrium affects how the vehicle would respond to wind forces, essentially acting like a seesaw. This is crucial in rocket design to ensure stable flight.

The discussion provides an insightful overview of the complexities and considerations in rocket design, particularly in optimizing for both performance and cost-effectiveness.

Soviet Mole’s Mechanism:

The discussion begins with the mention of a Soviet aerospace design, referred to as “the mole,” which had foldable wings. These wings weren’t dynamic; they were fixed in position. The mechanism was built to achieve a high angle of attack during initial ascent. The foldable back flaps were meant to extend lift and enable horizontal landing.

Comparison with Modern Designs:

The Soviet design is likened to Virgin Galactic’s Spaceship Two, which also has a changeable configuration that alters its center of pressure. However, like the Soviet design, it’s not dynamically adjustable. Both mechanisms switch from one operational mode to another to control their pitch or angle of attack.

Challenges in Dynamic Control:

Dynamic control for accurate landing is mentioned as a considerable challenge in these aerospace designs. Achieving pinpoint accuracy in landing is a complex feat when elements like pitch and angle of attack are continuously adjustable.

Starship’s Unique Approach:

Elon Musk adds that SpaceX’s Starship design is fundamentally different. Unlike the Soviet “mole” or Virgin Galactic’s Spaceship Two, which aim to generate lift, Starship’s primary objective is to generate drag. Starship is not an aircraft; it’s a vessel that is essentially falling, with the design optimized to be as draggy as possible during its descent, in contrast to aircraft that seek to be aerodynamic and lift-generating.

The conversation highlights the diverse approaches and challenges in aerospace design, from Soviet-era concepts to modern spacecraft like SpaceX’s Starship.

Size and Functionality of the High Bay:

Elon Musk describes the high bay’s dimensions, which is a little taller but significantly wider and deeper than its existing counterpart. The extra space allows for more manufacturing positions, vital for a high-production line focused on producing boosters or ships.

Transition to Permanent Buildings:

Elon Musk confirms plans to replace temporary tent-like structures with a permanent factory building. This construction will start from one end and gradually replace the existing tents. The aim is to create a more stable and expansive facility for manufacturing.

No Encompassing of High Bay:

The idea of constructing a building around the high bay is dismissed as “insane,” confirming that the high bay will remain a standalone structure.

Speculations and Continued Expansion:

Despite speculations that SpaceX’s activities might slow down due to rapid developments in Florida, Elon Musk indicates that the construction of a new permanent building suggests otherwise. The new building is already in the works, pointing to a continued focus on expansion.

The discussion sheds light on SpaceX’s plans to upscale its manufacturing capabilities by developing larger and more permanent facilities, highlighting a long-term commitment to production and expansion.

Introduction and Roles:

The speaker named Tim introduces himself and meets another individual, Andy Krebs, who is involved in engineering non-flight hardware. Andy works on high bays, factories, and launch pads.

Significance of Stage Zero:

Elon Musk briefly mentions the term “Stage Zero,” highlighting its importance. He points out that ground systems, inclusive of the tower, are as complex as stage one or stage two of a rocket. This suggests the significance of infrastructure in SpaceX’s operations.

Acknowledgements and Outreach:

Tim concludes the discussion by thanking Elon Musk and Ryan Chylinski for their time. He also acknowledges the support of his Patreon backers and promotes his online shop for space-related merchandise.

While the segment does not offer deep technical insights, it does shed light on the human aspect and the operational complexities involved in SpaceX’s endeavors, from the team members to the ground systems that support the space missions.