Circular runways
Circular runways
"If anyone ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me - it's all balls" - R J Mitchell
Re: Circular runways
Actually, if the circle is wide enough, it has something. Of course, it has, like a normal runway to be used in both directions, depending on the wind directions in some cases, because with a circle that size it will not be possible to actually reach the other side of the circle which is because the ways, aircraft can reach the airport are limited by neighboring airspaces.
Pros:
You just can't overrun a runway. Well, I guess, somewhere a moron is out there, who finds a way to jump his plane over the banking edge, but reasonably you can't.
The taxiing on the ground will be much easier to organize.
In most situations, approaches will be simpler and thus actually save fuel and environmental burdens.
It will decrease the number of crosswind landings, though not entirely make them obsolete, at least landings with a moderate crosswind component. (Nothing works optimal, actually, the points where planes can enter the circle is not entirely free but determined by the taxiways)
Cons:
It will take a long time to retrain all pilots and for a while, you have a lot of "Whut-daFuk" Asia Air pilots who will forget to steer to the inside of the circle.
We had a lot of crashes before the runway and a circle with a bankment endge going around is even less forgiving than most straight runways. Whatever you do, you have to get over this high edge and your touch down point has to be exactly in the circle and there is no "oops, lets touch down 200 feet later" thing because that will most likely smash you on the edge or worse, inside the circle.
The circular structure means, all service ways and roads have to be under ground. If you want to go with a car to the airport, you have to drive through tunnels leading under the runway and probably also under some taxiway. Which means, you have an extensive system of pretty big tunnels and their ventilation going under some concrete bed that carries an unknown number of 200 ton birds rumbling around with 100 to 200 knots. The maintenance and building costs will be enormous because the last thing you want is a landing 747-8 with 140 knots touching down right before the spot where under it crosses a six lane trafficway and find out, there were some cracks and you plane falls in a sinkhole ... with 140 knots for example.
Things I noticed in the video:
His estimation, a circular runway can handle the traffic of four normal runways, is plain wrong. He also contradicted it before when he said, up to three planes can use the circular runway at the same time. In reality, since you have obviously only one wind direction at the time, since big jets create a lot of jet wash and since they have such big wings, you can maybe, by clever taxiing and using the part before the take-off landing zone as line up area, get about 20-25% more density out of it.
Extreme high-traffic airports like Atlanta and airports serving a lot of different planes will probably need more than one circular runway and that means, they have to be concentric. Now, that will make the end approach quite wild because you are approaching in a quite narrow turn to get the optimal moment for your touch down ... only the guy on the inside of the circle maybe drifts a little more outside due to his weight and the centrifugal forces. So, you can only organize a zipper system. Which with two concentric runway would be as capable in number of planes as two straight runways, but with three concentric circles would actually lose as it looks.
So, the idea has a certain something and it would help some airports, but I am not sure it would be feasible for all of them. And given the problem we have already with pilot training, I suspect, we would be running into some problems, he doesn't expect yet. Like pilots aren't not trained for manual crosswind landing anymore, crews on blind ILS approaches get confused because the ILS entry points are dynamic (they move around the circle with the changing wind directions), pilots steer inside the circle on older airports which have no circle. Most problems will happen on the banking edge, I can see a lot of gears smashing into it. So, as a whole, it is maybe a good idea, but it needs still some thinking work about a lot of details that can cause follow up problems.
Pros:
You just can't overrun a runway. Well, I guess, somewhere a moron is out there, who finds a way to jump his plane over the banking edge, but reasonably you can't.
The taxiing on the ground will be much easier to organize.
In most situations, approaches will be simpler and thus actually save fuel and environmental burdens.
It will decrease the number of crosswind landings, though not entirely make them obsolete, at least landings with a moderate crosswind component. (Nothing works optimal, actually, the points where planes can enter the circle is not entirely free but determined by the taxiways)
Cons:
It will take a long time to retrain all pilots and for a while, you have a lot of "Whut-daFuk" Asia Air pilots who will forget to steer to the inside of the circle.
We had a lot of crashes before the runway and a circle with a bankment endge going around is even less forgiving than most straight runways. Whatever you do, you have to get over this high edge and your touch down point has to be exactly in the circle and there is no "oops, lets touch down 200 feet later" thing because that will most likely smash you on the edge or worse, inside the circle.
The circular structure means, all service ways and roads have to be under ground. If you want to go with a car to the airport, you have to drive through tunnels leading under the runway and probably also under some taxiway. Which means, you have an extensive system of pretty big tunnels and their ventilation going under some concrete bed that carries an unknown number of 200 ton birds rumbling around with 100 to 200 knots. The maintenance and building costs will be enormous because the last thing you want is a landing 747-8 with 140 knots touching down right before the spot where under it crosses a six lane trafficway and find out, there were some cracks and you plane falls in a sinkhole ... with 140 knots for example.
Things I noticed in the video:
His estimation, a circular runway can handle the traffic of four normal runways, is plain wrong. He also contradicted it before when he said, up to three planes can use the circular runway at the same time. In reality, since you have obviously only one wind direction at the time, since big jets create a lot of jet wash and since they have such big wings, you can maybe, by clever taxiing and using the part before the take-off landing zone as line up area, get about 20-25% more density out of it.
Extreme high-traffic airports like Atlanta and airports serving a lot of different planes will probably need more than one circular runway and that means, they have to be concentric. Now, that will make the end approach quite wild because you are approaching in a quite narrow turn to get the optimal moment for your touch down ... only the guy on the inside of the circle maybe drifts a little more outside due to his weight and the centrifugal forces. So, you can only organize a zipper system. Which with two concentric runway would be as capable in number of planes as two straight runways, but with three concentric circles would actually lose as it looks.
So, the idea has a certain something and it would help some airports, but I am not sure it would be feasible for all of them. And given the problem we have already with pilot training, I suspect, we would be running into some problems, he doesn't expect yet. Like pilots aren't not trained for manual crosswind landing anymore, crews on blind ILS approaches get confused because the ILS entry points are dynamic (they move around the circle with the changing wind directions), pilots steer inside the circle on older airports which have no circle. Most problems will happen on the banking edge, I can see a lot of gears smashing into it. So, as a whole, it is maybe a good idea, but it needs still some thinking work about a lot of details that can cause follow up problems.
Free speech can never be achieved by dictatorial measures!
Re: Circular runways
Certainly thought provoking
https://raw.githubusercontent.com/IAHM-COL/gpg-pubkey/master/pubkey.asc
R.M.S.
If we gave everybody in the World free software today, but we failed to teach them about the four freedoms, five years from now, would they still have it?
R.M.S.
If we gave everybody in the World free software today, but we failed to teach them about the four freedoms, five years from now, would they still have it?
Re: Circular runways
Maybe we build a circular airport circa homey in terragit, and those willing can bring anything to land there for a test....
https://raw.githubusercontent.com/IAHM-COL/gpg-pubkey/master/pubkey.asc
R.M.S.
If we gave everybody in the World free software today, but we failed to teach them about the four freedoms, five years from now, would they still have it?
R.M.S.
If we gave everybody in the World free software today, but we failed to teach them about the four freedoms, five years from now, would they still have it?
Re: Circular runways
Countries like the UAE will most likely utilize this. They already tax the crap out of their citizens to pay for their airlines, why not for the runways too?
Re: Circular runways
This is a dumb idea which has gotten way too much attention from the media and their "aviation experts".
Planes are not designed to flare for landing while banking, especially if there is windshear or low visibility. Also imagine what would happen if the runway was to become slippery due to weather...
The economic implications involved are also way out of hand. Such a change would not only require building new airports, but also restructuring the whole aviation infrastructure: re-engineering planes to become capable of landing on such runways, and upgrading their autoland system, retraining pilots and air traffic controllers, integrating an ILS system on each of the 36 "runways" (which is way too expensive to maintain for even a single runway), and redesigning the whole airspace structure. So it is obvious that the costs outweigh the benefits here (if there are any benefits at all).
Planes are not designed to flare for landing while banking, especially if there is windshear or low visibility. Also imagine what would happen if the runway was to become slippery due to weather...
The economic implications involved are also way out of hand. Such a change would not only require building new airports, but also restructuring the whole aviation infrastructure: re-engineering planes to become capable of landing on such runways, and upgrading their autoland system, retraining pilots and air traffic controllers, integrating an ILS system on each of the 36 "runways" (which is way too expensive to maintain for even a single runway), and redesigning the whole airspace structure. So it is obvious that the costs outweigh the benefits here (if there are any benefits at all).
Re: Circular runways
I don't think, slippery due to weather is the real problem here. It's not that those circular runways would be baked 22.5 degree or more and everybody would just slide down to the inside of the ring if there is rain. One main problem, those things wouldn't have though: Aqua planing. Since they are banked, water would always flow off to the inside if the circle.
The planes capable or not depends mostly on the diameter of the circle. Of course, those circles have to be biiiig, really big. Like 15,000ft diameter big at least. The ILS could be done with a central unit in the center, I guess, that's possible. And planes land all the time flaring and banking at the same time when there are crosswind conditions.
Where I see the bigger trouble is actually taking off. The thing may works fine, if everything works as planned. Fully loaded 777 freighter for example, if the circle is big enough, she has no problem to reach V1, all is good, she gets enough lift, off she goes and flies of tangential. But now imagine for a moment gusty weather. You get gusts with mostly headwind component, right when you start your run. That makes you a little bit slower to reach V1 (if you get the same gusts when you are almost at V1, it makes it a bit easier to get off the ground). So, the actual way you need is not static in reality. No problem if you have a straight runway of enough length, rotate 50 or even 100 feet earlier or later. But on a circle, you end up with not much pressure on the nose wheel, bad steer ability on the ground and the bankment working like a ski jump ramp for a plane with roughly 350 metric tons of weight and at this point maybe 140 knots or more fast.
Now imagine an even worse situation. An engine flames out or just goes dead. On a regular runway, if you are not too far down and too fast, you can abort. If you are beyond the point of no return, you can only try to compensate for the unequal push, get her up, circle and make an emergency landing. On a circle however, you have no runway end. So, if you manage to stay on it, you can abort always until you are actually in the air ... unless someone had the idea to use the circle to serve several planes at the same time to make up for the traffic density. Then your no-starter will probably hit the next plane on the circle from behind.
I think, especially incidents at failed take off runs will be a lot worse. To me, this feels like one of those ideas which sound good on the paper and then, when faced with reality, produce some problems nobody thought about beforehand.
The planes capable or not depends mostly on the diameter of the circle. Of course, those circles have to be biiiig, really big. Like 15,000ft diameter big at least. The ILS could be done with a central unit in the center, I guess, that's possible. And planes land all the time flaring and banking at the same time when there are crosswind conditions.
Where I see the bigger trouble is actually taking off. The thing may works fine, if everything works as planned. Fully loaded 777 freighter for example, if the circle is big enough, she has no problem to reach V1, all is good, she gets enough lift, off she goes and flies of tangential. But now imagine for a moment gusty weather. You get gusts with mostly headwind component, right when you start your run. That makes you a little bit slower to reach V1 (if you get the same gusts when you are almost at V1, it makes it a bit easier to get off the ground). So, the actual way you need is not static in reality. No problem if you have a straight runway of enough length, rotate 50 or even 100 feet earlier or later. But on a circle, you end up with not much pressure on the nose wheel, bad steer ability on the ground and the bankment working like a ski jump ramp for a plane with roughly 350 metric tons of weight and at this point maybe 140 knots or more fast.
Now imagine an even worse situation. An engine flames out or just goes dead. On a regular runway, if you are not too far down and too fast, you can abort. If you are beyond the point of no return, you can only try to compensate for the unequal push, get her up, circle and make an emergency landing. On a circle however, you have no runway end. So, if you manage to stay on it, you can abort always until you are actually in the air ... unless someone had the idea to use the circle to serve several planes at the same time to make up for the traffic density. Then your no-starter will probably hit the next plane on the circle from behind.
I think, especially incidents at failed take off runs will be a lot worse. To me, this feels like one of those ideas which sound good on the paper and then, when faced with reality, produce some problems nobody thought about beforehand.
Free speech can never be achieved by dictatorial measures!
Re: Circular runways
jwocky wrote: Like 15,000ft diameter big at least.
That's huge!!
If that's the case it would be just better to stick with shorter straight version of a runway (current model).
Also, just patch a whole 15000ft circle as a solid concrete platform (to create infinite heading straight 15000 ft length runways)
[Not environmental friendly, but forget about banking or landing in spins, or ending starting a land/take off head wind and finishing it on a cross-wind.
https://raw.githubusercontent.com/IAHM-COL/gpg-pubkey/master/pubkey.asc
R.M.S.
If we gave everybody in the World free software today, but we failed to teach them about the four freedoms, five years from now, would they still have it?
R.M.S.
If we gave everybody in the World free software today, but we failed to teach them about the four freedoms, five years from now, would they still have it?
Re: Circular runways
@Jwocky, it seems as if you are only thinking about rain. Imagine what happens when there is a layer of ice on the runway. This largely affects braking distance and steering. A slanted runway would only make this worse.
ILS is impossible with a transmitter in the center. The aircraft must be guided along one of the circle's imaginary tangent lines not a secant line through the center.
When landing on standard runways, even during crosswind conditions, the pilot never has to flare while banking until touchdown. It is common sense that the aircraft must be eventually wings level just before touchdown.
ILS is impossible with a transmitter in the center. The aircraft must be guided along one of the circle's imaginary tangent lines not a secant line through the center.
When landing on standard runways, even during crosswind conditions, the pilot never has to flare while banking until touchdown. It is common sense that the aircraft must be eventually wings level just before touchdown.
Re: Circular runways
I always thought circular TAXIWAYS would be a better idea. That video shows just how easy it is to make a wing/engine strike. And in turbulent/windy/freaky conditions, the pilot would have to constantly adjust during the banking turn. I have a hard time in a simulator on a straight runway (and apparently some pilots do too in real life).. what more one that requires you to make a banking turn..
How do you do a crosswind at the moment of touch down? Just imagine a sudden crosswind during touch down and the rudder turn right after that would have to be huuuge to compensate for the xwind + runway bank + runway radius...
How do you do a crosswind at the moment of touch down? Just imagine a sudden crosswind during touch down and the rudder turn right after that would have to be huuuge to compensate for the xwind + runway bank + runway radius...
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