Do you think we would ever use a circular runway?

In high temperatures, the length of runway becomes an issue. The density of air required to create lift becomes thinner than at an average or lower temperature. To compensate for this air anomaly, an extended runway is needed.

A pilot, Patrick Smith confirmed this when he said,

Hot air is less dense. This affects the output of the engines as well as aerodynamic capabilities, increasing the required runway distance and reducing climb performance. Therefore the amount of passengers and cargo a plane can carry are often restricted when temps are very high. How much so depends on the temperature, airport elevation and the length of the available runwaysBusiness Insider.

For more details, you can check my last article on it here.

A majority of modern runways has a length of 6000 feet (1828m), but some private airports can have runways as short as 400 feet (122m). That is the length of the runway in the Skyline Airport located in Inkom, Idaho of the USA.

Some commercial pilots consider a runway short if it is less than 2000 feet (609 meters). But sometimes engineers tasked with the job of building an ideal runway encounters a lot of challenges. The major one amongst it is the place with ample space that is flat.

Sometimes a look around will show an airport that due to space, the architectural engineers did build runways that are unique in the way of the design.

For example, between the Spain and Morrocco is the tiny British territory of Gibraltar. Such unique airport is Gibraltar's International airport which cuts across the busiest road in the area, the Winston Churchill Avenue is shown below

^{Image from Wikipedia Licenced CC-BY-SA-3.0 by Michael F. Mehnert: A panoramic view of the Gibraltar Airport showing a time-lapse image of an aeroplane take off while transversing a public road.}


Is there a way to manage such space constraint in building airports?

Could the result lie in the change of architectural design? That is, could we build a circular runway instead of the straight one we have now to have as much distance as the aeroplane needs for taking off?

The Circular Runway Idea

Some researchers at the Netherlands Aerospace came up with the idea of building a circular airport. The project which was named the Endless Runway since the runway will be circular and has no way of ending.

The project had a promotional video, done by a BBC reporter, which has been shared multiple times in social media and can be found here.

The video animation of what an airport with a circular runway showed a lot of advantages over the conventional straight runway. They include solving the problem of crosswind during landing.

Crosswind is a wind that is blowing (or has some component that is) perpendicular or at right angles to the direction of travel.

In aircraft, it may constitute a hazard that may prove fatal if not by careful manoeuvers from an experienced pilot.

The ability to land or for the take-off of three planes simultaneously is possible in a circular runway according to the project head researcher, Henk Hesselink.

Also since it is circular, the noise experienced by people living near the airport will be a thing of the past, or reduced to the barest minimum, since aeroplanes can approach the runway from any direction. Unlike conventional straight runway which only has one approach hence more noise concentration in a particular area.

How about the passengers? Won't they feel a little dizzy from all the turning similar to people in a rollercoaster ride?

Henk Hesselink again explained that the turn would not be that felt. That it will be of the same severity as when an aircraft makes a turn in the air. The centrifugal force will further provide an automatic brake to the aircraft that pushes it to the runway's centre.

He believes too it will be a good thing for the environment due to less fuel burnt in landings.

Then there is the efficiency of a circular runway, as it utilises less space to engage more aircraft. The circular runway has a similar capacity to that of four straight runways.

The research was supported by the European Union.

Another time in the past, January 10, 1960, Chicago Tribune ran a comic on the circular runway which reads.

The heart of tomorrow's airfield may be a circular catapult-like mechanism for sending planes into the air. It would mean runways much smaller than those now required.

For military purposes, American Engineering Company has already designed a giant wheel that is turned with great force by jet power. Cables from this wheel serve as catapults for fighting aircraft.

The next step would be to use rocket power to catapult planes from a dish-shaped concrete wheel. One spin on such a "circle runway" would produce the same starting speed that now requires a thousand feet or more of conventional runway, and with much less fuel.Source.

The only other time a real test was done on a circular runway was by the Navy in the year 1965. The December 13, 1965, edition of the Milwaukee Journal has the details of the Naval test of the circular runway in the Kirkland air force base at Albuquerque, New Mexico in the USA.

Too Good to be true?

Up till now, no one has ever built a circular commercial airport.

My grandmother used to say when things are too good to be true that it usually is.

Is this idea one of those ideas that are too good to be true?

But a retired pilot and now lecturer in Tourism and Airline Management at Edinburgh Napier University, Lindsay Cole has a different view on a circular runway.

He agreed that it sounds terrific on paper but building it is not something that is practical in the next couple of decades.

He stated that the reason for a specific route to an airport is not only a matter of only noise implication but to reduce chaos in poor weather where visibility is an issue. If airlines can land from any direction as in the case of a circular runway, that there would be many aircraft crashing into each other.

There is still the problem of elevation. Not all direction to an airport will be free of high ground that an aeroplane could run into when allowed to follow any approach to or from the airport.

Also, current pilots are trained to follow some specific symbols and lights in the airport. A circular airport makes it impossible for pilots to know where the airport begins or ends since it is a never-ending runway.

On the issue of crosswinds, Lindsay Cole agrees that there would be less severity of it in a short circular runway. But when the track is longer, the crosswinds effects will increase and decrease as the aircraft move during long takeoffs or landing. The same effect will occur on the headwind. The fluctuating circumstances will just be as bad, if not worse than is currently felt in the conventional system.

The old pilots will require retraining and may need to be highly trained to be able to navigate a circular runway during landing and takeoffs. Futhermore, the airport and aeroplane's equipment and design in use will have to be modified to handle the change from straight to circular.

This modification will require lots of infrastructural change and investments.

Do you think the circular runway will ever see the light of day?

REFERENCES

1. List of shortest runways
2. Think again: Will circular runways ever take off?
3. These Circular Runways Were Designed To Catapult Planes Skyward
4. This fantastic idea for a circular runway is sadly going nowhere