TIL how the space shuttle is connected to the width of a horse ass

At some point during lunch yesterday, colleagues and I started to discuss about space exploration. Rapidly, the space shuttle came in and I learned a very funny fact: the design of one of the most advanced piece of technology that the mankind has ever built, the space shuttle, is connected to the size of the ass of a horse.

More precisely, this fact does not concern the space shuttle itself, but the design of the rocket boosters necessary to launch the space shuttle into space. Those boosters are shown in the picture below, where one can notice the space shuttle, the orange main full tank and the two boosters attached to the left and to the right of the full tank.

_{[image credits: pixabay ]}

FROM THE SPACE SHUTTLE TO THE BRITISH RAILROAD

The rocket boosters of the space shuttle were made by an American company that had also had to take into account the transport of the boosters to the space shuttle launchpad by train. Therefore, no matter how large the engineers may have wanted to design the boosters, the specifications had to include the fact that the boosters have to fit on a train.

As a result, the size of the boosters is now connected to the size of the American trains. And the size of the trains is connected to the size of the railroad, or more precisely to the distance between the rails.

British expatriates are actually those who have built the American railroad system, an for this reason, US rails are similar to British rails.

The space shuttle design is now connected to the size of the British railroad system.

_{[image credits: pixabay ]}

FROM THE BRITISH RAILROAD TO THE OLD WHEEL RUTS

Let us continue our exploration and investigate why is the British railroad system as it is. The first English railway lines have been built by the same guys who built the tramways at that time, so that the distance between the rails is the same for both the trains and the trams.

Concerning the distance between the rails on a tramway line, it stems from the wagon specifications, and more precisely to the wagon wheel spacing. The reason is that the same tools and jigs have been used for tramway and wagon construction.

But why has the wagon wheel spacing been initially chosen such as it is? This choice was related to the status of some old long-distance and widely used roads, in which the wagons were better not to break. And the only way for preventing the wagons from breaking was to choose the wheel spacing to be the distance between the old wheel ruts on the roads.

We have now linked the space shuttle design to the spacing between the wheel ruts on the roads.

_{[image credits: pixabay ]}

THE GRAND FINALE: THE (ROMAN) EMPIRE STRIKES BACK

We can still push the exploration further. The oldest long distance roads in Europe were built by the Romans long long ago. And these roads have been used ever since!

The ruts on those roads, which the wagon specifications should account for in order not to break, were initially made by the Roman war chariots and the spacing between their wheels. And the latter has been made in such a way that a chariot could be carried by two horses.

This is why the size of the boosters of the space shuttle is designed in a way related to twice the width of the ass of a horse!

SOURCES

After hearing that story yesterday, I google it and I found many many websites referring to it. It is actually a true story. I will however only quote one website that I found pretty good, so that I could copy the conclusions shown in there: bureaucracy and specifications live forever!