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The Four-Inch Flight - A Lesson from History

It was 1960. The United States of America was locked in a race with the Soviet Union to get the first man into space. The US space agency NASA had rushed to prepare its next rocket for testing, and it stood ready on the launch pad.  Named Mercury-Redstone 1, the launch vehicle was over 25 metres tall and was the marriage of the Redstone rocket with the tiny Mercury capsule.

As the countdown approached the moment of launch, all appeared to be well. The scientists and engineers were observing from the blockhouse, a reinforced concrete bunker some 120 metres from the launch pad. But as they watched, things did not go to plan.

As you can see from the video, the rocket engines fired, but then stopped again very quickly. What followed were several seemingly random events. The first thing to happen was the escape tower disappearing in a cloud of smoke, followed by the release of the recovery parachute that was designed to carry the Mercury capsule safely back to Earth. You will notice that the parachute did not inflate. This is hardly surprising, as the capsule was sat motionless on its launchpad.

The whole rocket had travelled 4 inches. 10 centimetres. Less than the length of your smartphone.

Everything then fell silent but the potential for disaster was still high. Here was a rocket, full of fuel, powered by internal batteries and packed with explosive charges. However, luck was on NASA’s side – the wind was gentle, and the rocket stayed safely upright. What began as a dangerous situation ended as an amusing comedy of errors. But what had gone wrong?

The cause of this multi-million-dollar failure was a plug. Or, more accurately, two plugs. The Redstone rocket was designed with two umbilical connectors, one used for control, the other for power. They were designed so that, on lift-off, the control connector separated first, followed a fraction of a second later by the power connector.

For the Mercury-Redstone 1 launch, the wrong control connector had been installed. It was longer and had been designed for a different rocket, with the result that the power connector had separated first rather than second. In this event, the internal safety systems of the rocket had followed their programmed logic and the rocket engines were shut down. Everything that followed was a direct result of the engine shut down.

The moral of the story is that components matter. It does not matter how insignificant the component may appear to be; the fact is that one failure can bring a huge system to a grinding halt.

Let us apply this lesson in an up-to-date setting. Unlike machines of the pre-electronics era, modern equipment is so dependent on electronics that a single component could be the difference between a successful mission and a potentially deadly failure. It is possible that the failed component is almost too small to be seen with the naked eye.

Users of modern electronics do not tend to have the skills or technology to fix the equipment themselves. This is a luxury reserved for much older technology. As an example, the Douglas DC-3 aircraft is still being used commercially more than 80 years after its first flight. The reason is that a DC-3 can be repaired in the wilds of Alaska with little more than basic tools and a bit of know-how. The same cannot be said of most modern machines, and so it is vitally important that the designer chooses the right component from the outset.

To conclude our story, NASA redesigned its rocket to prevent a similar event from happening again. Less than 6 months later, another Mercury-Redstone launch vehicle carried Astronaut Alan Shepard into space. With that mission, the United States was finally on the path that ended with Neil Armstrong stepping onto the surface of the moon 8 years later.

Don’t let an approaching deadline or a tight budget force you into making the wrong choice of component. You may be faced with a disaster or just acute embarrassment. Is either worth the few minutes or pennies you might save?

Because components, even small components, matter!

Connector Geek is Dave in real life. With 29 years in the industry, Dave still likes talking about connectors almost as much as being a Dad to his two kids. He still loves Lego too...

9 Dec 2019, 15:51

Comments

December 13, 2019 10:12

Strangely, I always enjoy an article about Redstone rockets...
But more seriously, a great cautionary tale for designers.

0 Votes

December 13, 2019 10:12

@Redstone I thought of you when reading this too! :o)

December 10, 2019 14:56

Really interesting article - love anything to do with NASA/the space race. There are so many factors that could potentially go wrong with their projects, it blows my mind. Details matter!