Why aren't runways circular?
Discussion
Well, if we can have hybrid aircraft...
Consider the neverending row about where to site a new London runway. Runways are cumbersome, inconveniently proportioned things, and people get upset when their houses are knocked down to build them.
Heathrow's runways are about 4km long, give or take. The same distance could be achieved with a single lap of a banked circular runway just one third of the size of a straight runway. If take-offs and landings were achieved over several laps, the circular runways could be much smaller.
The banking would avoid excessive lateral forces on takeoff, the only difference from a straight runway that passengers would experience is a gentle downward force as they are pressed into their seats a bit. But not much. And the extra 'weight' caused by accelerating around a banked circular runway vanishes as soon as the aircraft flings out (the new phrase for take-off).
As a circular runway is infinite in length it would be safer in the event of engine failures and similar emergencies, and it would also allow aircraft to accelerate to fling-out speed over a longer distance, thus saving fuel and mechanical wear and tear.
A circular runway would be viable in any wind direction (the captain simply chooses an upwind fling-out point on takeoff and flush point on landing.
What's not to like?
Consider the neverending row about where to site a new London runway. Runways are cumbersome, inconveniently proportioned things, and people get upset when their houses are knocked down to build them.
Heathrow's runways are about 4km long, give or take. The same distance could be achieved with a single lap of a banked circular runway just one third of the size of a straight runway. If take-offs and landings were achieved over several laps, the circular runways could be much smaller.
The banking would avoid excessive lateral forces on takeoff, the only difference from a straight runway that passengers would experience is a gentle downward force as they are pressed into their seats a bit. But not much. And the extra 'weight' caused by accelerating around a banked circular runway vanishes as soon as the aircraft flings out (the new phrase for take-off).
As a circular runway is infinite in length it would be safer in the event of engine failures and similar emergencies, and it would also allow aircraft to accelerate to fling-out speed over a longer distance, thus saving fuel and mechanical wear and tear.
A circular runway would be viable in any wind direction (the captain simply chooses an upwind fling-out point on takeoff and flush point on landing.
What's not to like?
Thinking outside the box... Like it. 
2 points regarding landings, to land on a straight runway the plane has to hit a point probably somewhere within a 100 metre stretch (????), To land on a curved runway, the land point would have to be a lot more accurate.
And the runway would be on a side slope, the plane would generally be coming in wings level. Would the bank of the runway be sufficiently low that the wing would not be in danger of touching before the wheels??
2 points regarding landings, to land on a straight runway the plane has to hit a point probably somewhere within a 100 metre stretch (????), To land on a curved runway, the land point would have to be a lot more accurate.
And the runway would be on a side slope, the plane would generally be coming in wings level. Would the bank of the runway be sufficiently low that the wing would not be in danger of touching before the wheels??
Chester draws said:
Thinking outside the box... Like it.
2 points regarding landings, to land on a straight runway the plane has to hit a point probably somewhere within a 100 metre stretch (????), To land on a curved runway, the land point would have to be a lot more accurate.
And the runway would be on a side slope, the plane would generally be coming in wings level. Would the bank of the runway be sufficiently low that the wing would not be in danger of touching before the wheels??
I see where you are coming from my dear Chester, but the final approach would not be a tangent to the circle but more of a circle itself so the pilot has infinite runway length to land on. Landing would be in a bank with wings parallel to the runway.2 points regarding landings, to land on a straight runway the plane has to hit a point probably somewhere within a 100 metre stretch (????), To land on a curved runway, the land point would have to be a lot more accurate.
And the runway would be on a side slope, the plane would generally be coming in wings level. Would the bank of the runway be sufficiently low that the wing would not be in danger of touching before the wheels??
I can see that in theory it would work except:
A: The diameter would have to so huge that it would take more land than a straight runway
B: It could only be tuned to match one exact aircraft (in one specific condition). Basically the takeoff and touchdown speeds and resultant bank angle to maintain the turn radius would be different for every aircraft so they would all be landing and taking off on one sides wheels before the other, probably not tremendously safe.
C: If there was a cockup instead of just rolling onto the grass or sand in a predefined direction the aircraft would launch itself off over the lip and come crashing down in a completely unpredictable direction.
A: The diameter would have to so huge that it would take more land than a straight runway
B: It could only be tuned to match one exact aircraft (in one specific condition). Basically the takeoff and touchdown speeds and resultant bank angle to maintain the turn radius would be different for every aircraft so they would all be landing and taking off on one sides wheels before the other, probably not tremendously safe.
C: If there was a cockup instead of just rolling onto the grass or sand in a predefined direction the aircraft would launch itself off over the lip and come crashing down in a completely unpredictable direction.
Ayahuasca said:
Well, if we can have hybrid aircraft...
Consider the neverending row about where to site a new London runway. Runways are cumbersome, inconveniently proportioned things, and people get upset when their houses are knocked down to build them.
Heathrow's runways are about 4km long, give or take. The same distance could be achieved with a single lap of a banked circular runway just one third of the size of a straight runway. If take-offs and landings were achieved over several laps, the circular runways could be much smaller.
The banking would avoid excessive lateral forces on takeoff, the only difference from a straight runway that passengers would experience is a gentle downward force as they are pressed into their seats a bit. But not much. And the extra 'weight' caused by accelerating around a banked circular runway vanishes as soon as the aircraft flings out (the new phrase for take-off).
As a circular runway is infinite in length it would be safer in the event of engine failures and similar emergencies, and it would also allow aircraft to accelerate to fling-out speed over a longer distance, thus saving fuel and mechanical wear and tear.
A circular runway would be viable in any wind direction (the captain simply chooses an upwind fling-out point on takeoff and flush point on landing.
What's not to like?
Have a go at flying some RC model aircraft. It’ll allow you to realise just how unattainable this solution is. Consider the neverending row about where to site a new London runway. Runways are cumbersome, inconveniently proportioned things, and people get upset when their houses are knocked down to build them.
Heathrow's runways are about 4km long, give or take. The same distance could be achieved with a single lap of a banked circular runway just one third of the size of a straight runway. If take-offs and landings were achieved over several laps, the circular runways could be much smaller.
The banking would avoid excessive lateral forces on takeoff, the only difference from a straight runway that passengers would experience is a gentle downward force as they are pressed into their seats a bit. But not much. And the extra 'weight' caused by accelerating around a banked circular runway vanishes as soon as the aircraft flings out (the new phrase for take-off).
As a circular runway is infinite in length it would be safer in the event of engine failures and similar emergencies, and it would also allow aircraft to accelerate to fling-out speed over a longer distance, thus saving fuel and mechanical wear and tear.
A circular runway would be viable in any wind direction (the captain simply chooses an upwind fling-out point on takeoff and flush point on landing.
What's not to like?
MrBarry123 said:
Johnnytheboy said:
How about circular in the vertical plane (if you'll excuse the pun)?
i.e. a loop-the-loop?
Get some speed up, hit the loop and go round until take off speed is achieved = short runway!
I like this idea.i.e. a loop-the-loop?
Get some speed up, hit the loop and go round until take off speed is achieved = short runway!
This has to be betterer!
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