How Specifications Live Forever
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When you see a space shuttle sitting on the launch pad,
there are two big booster rockets attached to the sides
of the main fuel tank. These are the solid rocket boosters,
or SRBs.

The SRBs are made by Morton Thiokol at a factory in Utah.

Originally, the engineers who designed the SRBs wanted
to make them much fatter than they are.
Unfortunately, the SRBs had to be shipped by train
from the factory to the launch site in Florida
and the railroad line runs through a tunnel in the
mountains.
The SRBs had to be made to fit through that tunnel.

Now, the width of that tunnel is just a little wider than the
U.S. Standard Railroad Gauge
(distance between the rails) of 4 feet, 8.5 inches.

That's an exceedingly odd number.
Did you ever wonder why that gauge was used?
Because US railroads were designed and built by
English expatriates, and that's the way they built them
in England.

Okay, then why did the English engineers
build them like that?

Because the first rail lines of the 19th century were built
by the same craftsmen who built the pre-railroad
tramways, and that's the gauge they used.

I'll bite, why did those craftsmen choose that gauge?
Because they used the same jigs and tools that were previously used for building wagons, and you guessed it,
the wagons used that wheel spacing.

Now I feel like a fish on a hook!
Why did the wagons use that odd wheel spacing?

Well, if the wagon makers and wheelwrights of the time
tried to use any other spacing, the wheel ruts on some
of the old, long distance roads
would break the wagon axles.
As a result, the wheel spacing of the wagons
had to match the spacing of the wheel ruts
worn into those ancient European roads.

So who built those ancient roads?

The first long distance roads in Europe were built by
Imperial Rome for the benefit of their legions.
The roads have been used ever since.

And the ruts?

The initial ruts, which everyone else had to match
for fear of destroying their wagons, were first made by
Roman war chariots.
And since the chariots were made by
Imperial Roman chariot makers,
they were all alike in the matter of wheel spacing.

Well, here we are. We now have the answer to the
original question. The United States standard railroad
gauge of 4 feet, 8.5 inches derives from the original specification for an Imperial Roman army war chariot.

Specs and bureaucracies live forever.

That's nice to know, but it still doesn't answer why the
Imperial Roman war chariot designers chose to spec
the chariot's wheel spacing at exactly 4 feet, 8.5 inches.

Are you ready?

Because that was the width needed to accommodate
the rear ends of two Imperial Roman war horses!!!

Well, now you have it. The railroad tunnel through which
the late 20th century space shuttle SRBs must pass was excavated slightly wider than two 1st century horses' butts.

Consequently, a major design feature of what is arguably
the world's most advanced transportation system was
spec'd by the width of a horse's behind!

So, the next time you are handed a specification
and wonder what horses' rear end came up with it,
you may be exactly right.
Now you know what is "behind" it all.

~Author Unknown~

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inventing and writing forum
You dont know how little you know.
till you know enought
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What hope humanity? Its a long rope that links the shuttle solid bosters size to the butt of two roman horses. Your point is well stated.
Tell the idiots to make it on site and twice as big, asap. NASA has some catching up to do. China and Japan are both entering the quest for space presance. There is some discusion about maned space basess on the Moon., and I dont see NASA as in the race this time. Dispite the Bush push. Come on NASA dont sit there waiting, lets get on with it.

I seem to remember reading somewhere that the Chinese track gauge is 5 feet 6 inches. Then again there was also a famous British Engineer in the early 1800s who tried to go for a 7 foot track gauge but his idea became the victim of the first industrial "format" war and suffered the same fate as Betamax. Sometimes orginal ideas do not pay even if they are better. Go with the flow, follow the herd and accept second best is often the normal human reaction.

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Note 1. All requests for planetary demolition must now be submitted in quadruplicate on form UX-565/B4 and be counter-signed by the assistant administrative officer for interstellar traffic calming - department QG-7. Subject to approval by the chief planning officer and the infrastructure development coordination sub-committee.

This is sort of an urban legend.
http://www.snopes.com/history/american/gauge.htm

Hey I like that. I like it so well that I have decided to print it and take it to work.

I have a saved copy of this from several years ago. It was written by some NASA engineer that got curious about the booster. I've always loved to pass a copy to people whenever they talk about doing something because "we've always done it that way."

The version I have was authored by Howard Winsett - NASA Dryden Flight Research Center.

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...and we'll be saying a big hello to all intelligent life forms everywhere; and to everyone else out there, the secret is to bang the rocks together, guys...

john l
thanks for that info
i love the story as im an inventor and always question what is established
and do i find some whopper design mistakes. in everyday life.

like mobility scooters with optional tiller steering WTF that went out in 1906 on car design.

__________________
inventing and writing forum
You dont know how little you know.
till you know enought
to know that you still know nothing