Why Elon Musk Chose Not to Use Landing Legs for the BFR (formerly Falcon Heavy)

The decision made by Elon Musk not to use landing legs on the BFR (formerly known as the Falcon Heavy) spacecraft is a fascinating aspect of aerospace engineering. This choice is contrary to the design of the current Falcon 9 and Falcon Heavy rockets, which do use landing legs. Let's delve into the reasoning behind this unique design decision and explore the benefits and challenges it poses.

The Role of Precision and Stability

The more precise the landing gear design, the more weight and complexity it introduces. According to Musk, for a rocket of the size of the BFR, precision landing is not a practical or necessary feature. Instead, an alternative method is employed, where the rocket is captured by massive arms often referred to as “chopsticks.”

As the rocket descends, its engines slow it down, but it is the catchment mechanism provided by the “chopsticks” that ensures a controlled landing. Musk states that this approach is more efficient and reliable, as seen in the demonstration where they managed to save about 5 to 10 tons of weight by eliminating the need for retractable landing legs.

Engineering Efficiency and Reliability

Musk believes in the simplicity of design, reducing unnecessary components to enhance both efficiency and reliability. According to his reasoning, the size of the BFR and its aerodynamics render retractable landing legs unnecessary. The fins on the BFR serve a different purpose and are utilized as control surfaces during the reentry phase. In fact, the BFR has been updated to include retractable legs, which serves a crucial role in the landing process.

Practical Considerations and Infrastructure

To further justify the decision to forgo landing legs, Musk mentioned the lack of infrastructure on Mars. In the context of Mars landings, there are no towers or landing pads available to support the spacecraft. Hence, the use of huge arms to catch the rocket is a practical solution, given the available conditions.

Latest Iteration and Design Changes

The latest iteration of the BFR has undergone significant design changes. Earlier prototypes featured three fins, but these have been replaced with two large flaps on the bottom of the Starship, set 180 degrees apart. Additionally, two small canards are positioned at the top. These flaps and canards are not used as aerodynamic stabilizers but rather as control surfaces during the reentry phase, referred to as the “bellyflop” phase.

Musk and his team have developed a new system that enhances reliability and minimizes the risk of failure. The video of the latest iteration shows the new flap configuration in action, highlighting the innovative approach taken to ensure a safe and stable landing.

Conclusion

Elon Musk's decision to avoid landing legs on the BFR showcases his commitment to simplicity and reliability in design. While this approach may seem unconventional, it is designed to meet the specific demands and constraints of the mission. The reliance on a different type of landing mechanism underlines the importance of adapting to environmental and infrastructural challenges, demonstrating the versatility and resilience of aerospace engineering.

Understanding the rationale behind this design choice provides valuable insights into the complexities of rocket design and the continuous pursuit of innovative solutions in the field of space exploration.