When audacious engineering leads to major success, Part 1: SpaceX booster

The Mars Rover Sky Crane, SpaceX Self-Landing Booster, and the Apollo Lunar Lander are just a few examples of dramatic, radically unconventional thinking, leading to astounding successes.

Bringing a major engineering project from concept to successful conclusion is a combination of often-elusive factors of skill, understanding, determination, risk, diligence, perseverance, good fortune (luck), and many other hard-to-quantify factors. In some cases, it also requires outright audacity in the basic concept, sometimes referred to as “out of the box” thinking.

This article will look briefly at some audacious engineering examples: the SpaceX reusable rocket booster and the Mars Perseverance Rover, followed by a third, in-depth look at the Apollo moon-landing approach. Coincidentally — or perhaps not — the three cited examples all involve rocketry in various forms (that’s a good subject for an engineering roundtable or forum). In some ways, they are physical embodiments of the ideas presented in Samuel C. Florman’s 1976 book, “The Existential Pleasures of Engineering.”

Of course, audacious engineering is not limited to space and rocketry, as can be seen in developing the first nuclear-powered submarine (Related Content 1 and 2). In that case, Admiral Hyman Rickover, who instigated and led the development, went totally against conventional thinking that it was necessary to build a wide-open, large-than-final reactor prototype to work out the design. Instead, he concluded that any such large-scale prototype would need countless small and large changes when “shrunk” to fit the actual reactor going into the submarine (Figure 1). That unit would actually be an entirely new engineering project. Much of the test-bed prototyping work would be misleading or even irrelevant with respect to performance, thermal issues, maintenance, on-board realities, and more.

Fig 1: This saltwater tank was used as a test bed for the prototype submarine reactor design, development, and evaluation while an identical reactor was being built and installed in parallel in the Nautilus submarine. (Image: Naval Reactors History Database via Pinterest)

Instead, Rickover pushed for an “all up” approach. The first working prototype was designed to fit into the space and conditions of the submarine in the same operating environment and settings. As a result, there were relatively few surprises when the second reactor needed for submarine installation was built based on that first working prototype.

This “all up” approach was also adopted for testing the Saturn launch vehicle for the moon landing: project leaders eventually realized that incremental assembly and the test would consume time and energy but yield only somewhat useful results. The reason was that the set-up and test procedures for these intermediate arrangements were actually very different than they would have to be for the final configuration, and many of the lessons learned and the associated effort would not be applicable (Reference 1).

Of course, there have been many examples of audacious engineering before the 20^th century. The successful laying of the first trans-Atlantic submarine telegraph cable took many “it can’t be done” innovations as well as a huge amount of commitment, faith, perseverance, and money beyond any normal scope (Related Content 3 and 4). Similarly, the design of the world’s fastest ocean liner, the S.S. United States was more than an outstanding power plant and innovative hydrodynamic designs; it also was the world’s only large ship with a complete absence of combustible materials (Related Content 5 through 8).

The SpaceX Falcon Booster

Not all such space-related audacity takes place far from Earth. Since the earliest days of large multistage rockets, the first-stage booster was often wasted, usually by having it drop into the ocean; some attempts to bring it back for re-use using parachutes, but these were generally unsuccessful. The result was the unavoidable loss of valuable hardware with associated cost and additional production time and effort needed to build another booster. For many years the “dream” for many years was to build a booster that could return itself to Earth in a stand-up position and could be refurbished and reused.

SpaceX finally realized the goal with their Falcon 9 heavy booster. It has successfully landed itself multiple times by backing down and parking itself onto a ground-based landing pad and even a floating drone platform (there have been failures, too, of course). Doing this takes the integration of many technologies and disciplines, including GPS, inertial guidance, precise engine restart engine gimbaling, retrorockets, and even special gas jets at the booster’s top to change its orientation to prepare for self-landing once it has been separated from the other stages) (Figure 2, References 2, 3, and 4). Despite very legitimate skepticism from many experienced rocket engineers and some dramatic early failures, the Falcon 9 has demonstrated that it can be done consistently.

Fig 2: The schematic shows how the SpaceX Falcon 9 booster uses small control rockets at its top to re-orient itself for the autonomous self-landing trajectory with different paths for landing on a ground pad versus floating dock. (Image: Art of Engineering/Reference 3))

The next part of this article looks at the “Sky Crane” used for the landing of the Mars Curiosity Rover, a solution that had to be invoked when all other more-conventional approaches were eventually ruled out.

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