Ancient Rome and Spaceflight
from Gerhard Holtkamp, 28. November 2010, 18:59
Have you ever heard about how engineering in ancient Rome effected the design of the Space Shuttle? A nice story - but ultimately incorrect...
While reading a romance novel (my friends will be shocked - I occasionally read things other than science papers and technical journals!) I came across the mentioning of how Roman engineers had influenced specifications of our modern railways. To be more exact the story links the dimension of the standard rail gauge to the Roman war chariots and it roughly goes like this:
60% of the world's railways use the standard gauge (also called normal gauge) with a spacing between the rails of 1.435 meters and the question arises as to why this strange number? Well, railways were invented in Britain and you should convert it into Imperial units. However the resulting 4 feet, 8½ inches sounds as odd.
But the people who built the first railways had started out building tramways and that's the gauge they used there. And that in turn was because they used the same tools also used for horse-drawn wagons on the road. Now the spacing of wagon wheels was dictated by wheel ruts left on old roads by whoever used them first because the wheels wouldn't last too long otherwise.
As the first long-distance roads in Europe were built by Imperial Rome for their military the ruts in the roads came from standard Roman war chariots. The conclusion is that the rail gauge used by British railroad pioneers owes its size to ancient Roman engineering. With the export of British railroad technology to other countries the standard gauge thus was established in much of the world.
To make the story even more spicy the Solid Rocket Boosters (SRBs) of the Space Shuttle are invoked. They are built in Utah and have to be shipped via rail to the Kennedy Space Center in Florida. This restricted the diameter of the SRBs it is claimed due to a tunnel which had to be passed. So even modern spaceflight was effected by ancient Roman engineering.
I vaguely remembered having heard about this story (minus the SRB part) many years ago. Intrigued I checked the Internet and quickly found out (a little to my disappointment) that the story as such is incorrect. Nevertheless there are some truthful bits and pieces to it.
The first railway pioneers had indeed started out with tramways built predominantly to support mining operations with horse-drawn wagons. These wagons were similarly sized to the ones used on roads but the tramway gauges could still vary between 4 feet and 5 feet.
When English pioneer George Stephenson built his first railway he used a gauge of 4 feet, 8 inches which was very close to the spacing used by Imperial Roman war chariots.(He later widened this by 0.5 inches to 4 feet, 8½ inches as this seems to have provided extra free movement in curves.) But Stephenson's choice was not made because of some existing ruts in old Roman roads but rather because this is a typical spacing if you try to harness a horse or two in front of carts or chariots and have them move with reasonable comfort.
So while Stephenson's gauge owes something to horse-drawn wagons it would be wrong to trace it back to the Romans. But this wasn't the only railway gauge used in 19th century Britain. These could be as small as 4 feet or as large as 7 feet. By the middle of the (19th) century a Royal Commission decided to standardize the railway system. Due to his engineering skills Stephenson had been commisioned to build far longer lines than his next rival so his gauge became the standard gauge.
Apart from better designed engines Stephenson's success was probably also due to economics - balancing cheaper but less capable narrow gauge lines against more expensive broad gauge lines. The important point is that it was not the Roman war chariots that invariably led to our standard railway gauge but because Stephenson's got selected amoung already existing competing designs due to superior engineering (and maybe economics).
As Stephenson was also very successful exporting railways to other countries his gauge quickly became the standard in those countries as well. But 40% of the world's railways use different gauges for all kinds of reasons. In the course of this little investigation I came across a remark that the network on the Iberian peninsula runs on a broad gauge because the military in 19th century Spain was wary of a possible French invasion and wanted to prevent the French army to use their own rolling stock for logistics.
Whether in light of today's technology a different gauge would be preferred I don't know. But once a standard has been adopted you wouldn't want to rebuild the existing dense network unless you set up special purpose lines. I once read a report in a youth magazine about Russian plans for a nuclear powered railroad which would have required a much larger gauge of maybe 4 meters or so. But that was in the 1950s when atomic power was at its most popular - it never got beyond an early planning stage and you wouldn't find too many supporters nowadays!
When design started for what was to become the grandmother of modern rockets - the German A4 (better known as V2) - one of the initial requirements stated that the fully assembled rocket would have to comply with maximum dimensions allowed for road as well as for rail transport, the latter being essentially limited by the size of tunnels. So the rocket's maximum diameter would have been determined by the standard gauge, right? Well not quite.
Sizing tunnels is a rather complex issue. Tunnels are not built around the rails like a tight dress barely fitting a fashion model. A variety of issues have to be considered among them the aerodynamics of trains and their speed. A typical modern tunnel can have about twice the cross-sectional area than early tunnels. Consequently the maximum dimensions of goods to be transported by rail can vary according to country and line and is only vaguely connected to the railway gauge.
As for the Space Shuttle SRBs they do of course have to comply with regulations for rail transport in the U.S. but had it been desirable to use much wider SRBs one could have built a special plant somewhere along the coast or some inland waterway to allow transport via barge. This is exactly what has been done with the much larger Shuttle's External Tank. So you definitely cannot link the Shuttle design with the size of horse-drawn carriages.
Thus our standard railway gauge goes back to engineering decisions made less than two centuries ago. There are probably a number of other standards we take for granted that can be traced back for a century or two. All of which makes me wonder about the many standards defined in our days. Will they have a profound influence on engineering a century or two from now?
While reading a romance novel (my friends will be shocked - I occasionally read things other than science papers and technical journals!) I came across the mentioning of how Roman engineers had influenced specifications of our modern railways. To be more exact the story links the dimension of the standard rail gauge to the Roman war chariots and it roughly goes like this:
60% of the world's railways use the standard gauge (also called normal gauge) with a spacing between the rails of 1.435 meters and the question arises as to why this strange number? Well, railways were invented in Britain and you should convert it into Imperial units. However the resulting 4 feet, 8½ inches sounds as odd.
But the people who built the first railways had started out building tramways and that's the gauge they used there. And that in turn was because they used the same tools also used for horse-drawn wagons on the road. Now the spacing of wagon wheels was dictated by wheel ruts left on old roads by whoever used them first because the wheels wouldn't last too long otherwise.
As the first long-distance roads in Europe were built by Imperial Rome for their military the ruts in the roads came from standard Roman war chariots. The conclusion is that the rail gauge used by British railroad pioneers owes its size to ancient Roman engineering. With the export of British railroad technology to other countries the standard gauge thus was established in much of the world.
To make the story even more spicy the Solid Rocket Boosters (SRBs) of the Space Shuttle are invoked. They are built in Utah and have to be shipped via rail to the Kennedy Space Center in Florida. This restricted the diameter of the SRBs it is claimed due to a tunnel which had to be passed. So even modern spaceflight was effected by ancient Roman engineering.
I vaguely remembered having heard about this story (minus the SRB part) many years ago. Intrigued I checked the Internet and quickly found out (a little to my disappointment) that the story as such is incorrect. Nevertheless there are some truthful bits and pieces to it.
The first railway pioneers had indeed started out with tramways built predominantly to support mining operations with horse-drawn wagons. These wagons were similarly sized to the ones used on roads but the tramway gauges could still vary between 4 feet and 5 feet.
When English pioneer George Stephenson built his first railway he used a gauge of 4 feet, 8 inches which was very close to the spacing used by Imperial Roman war chariots.(He later widened this by 0.5 inches to 4 feet, 8½ inches as this seems to have provided extra free movement in curves.) But Stephenson's choice was not made because of some existing ruts in old Roman roads but rather because this is a typical spacing if you try to harness a horse or two in front of carts or chariots and have them move with reasonable comfort.
So while Stephenson's gauge owes something to horse-drawn wagons it would be wrong to trace it back to the Romans. But this wasn't the only railway gauge used in 19th century Britain. These could be as small as 4 feet or as large as 7 feet. By the middle of the (19th) century a Royal Commission decided to standardize the railway system. Due to his engineering skills Stephenson had been commisioned to build far longer lines than his next rival so his gauge became the standard gauge.
Apart from better designed engines Stephenson's success was probably also due to economics - balancing cheaper but less capable narrow gauge lines against more expensive broad gauge lines. The important point is that it was not the Roman war chariots that invariably led to our standard railway gauge but because Stephenson's got selected amoung already existing competing designs due to superior engineering (and maybe economics).
As Stephenson was also very successful exporting railways to other countries his gauge quickly became the standard in those countries as well. But 40% of the world's railways use different gauges for all kinds of reasons. In the course of this little investigation I came across a remark that the network on the Iberian peninsula runs on a broad gauge because the military in 19th century Spain was wary of a possible French invasion and wanted to prevent the French army to use their own rolling stock for logistics.
Whether in light of today's technology a different gauge would be preferred I don't know. But once a standard has been adopted you wouldn't want to rebuild the existing dense network unless you set up special purpose lines. I once read a report in a youth magazine about Russian plans for a nuclear powered railroad which would have required a much larger gauge of maybe 4 meters or so. But that was in the 1950s when atomic power was at its most popular - it never got beyond an early planning stage and you wouldn't find too many supporters nowadays!
When design started for what was to become the grandmother of modern rockets - the German A4 (better known as V2) - one of the initial requirements stated that the fully assembled rocket would have to comply with maximum dimensions allowed for road as well as for rail transport, the latter being essentially limited by the size of tunnels. So the rocket's maximum diameter would have been determined by the standard gauge, right? Well not quite.
Sizing tunnels is a rather complex issue. Tunnels are not built around the rails like a tight dress barely fitting a fashion model. A variety of issues have to be considered among them the aerodynamics of trains and their speed. A typical modern tunnel can have about twice the cross-sectional area than early tunnels. Consequently the maximum dimensions of goods to be transported by rail can vary according to country and line and is only vaguely connected to the railway gauge.
As for the Space Shuttle SRBs they do of course have to comply with regulations for rail transport in the U.S. but had it been desirable to use much wider SRBs one could have built a special plant somewhere along the coast or some inland waterway to allow transport via barge. This is exactly what has been done with the much larger Shuttle's External Tank. So you definitely cannot link the Shuttle design with the size of horse-drawn carriages.
Thus our standard railway gauge goes back to engineering decisions made less than two centuries ago. There are probably a number of other standards we take for granted that can be traced back for a century or two. All of which makes me wonder about the many standards defined in our days. Will they have a profound influence on engineering a century or two from now?
Ah, but there, dear Gerhard, you are ignoring a crucial issue: A spacecraft design incorporates many different dimensions. Length, span, height, thrust, mass ... and politics. Getting all of the technical things right but being short on politics will render the design as unfeasible as, say, excessive mass or insufficient thrust.
It is important that components for a project as vast as the Space Shuttle be produced in states whose representatives in Congress have the authority to pull strings in appropriation committees.
If that means building components such as the SRB in a land-locked state (Utah), then too bad, but that's a hrd requirement, one that cannot be waived under any circumstances.
Michael, you are absolutely right that politics is as important in spacecraft design as the technical specifications. But had there been a real desire for building much larger SRBs it might have been possible to trade building them in Utah for some other important item.
I'm not certain about the details of engineering choices made for the Shuttle with regard to the SRBs but my guess is that one wanted to use as much of the already existing expertise of building large solid fuel ICBMs for the military and used that as a starting point. Those were already manufactured in Utah (I think) and they had to be able to be transported to land-locked silos for deployment.
But as was the case with the German A4 this still doesn't tie them too closely with the standard gauge because of what I said with regard to tunnel design.