BBC: Will Circular Runways Ever Take Off?

Sightseer · Thu Mar 16, 2017 2:39 am

I saw this on the BBC Android app and was understandably curious about what it had to say. The premise is that airport runways could be banked circles that would allow for less noisy airspace and prevent crosswind landings. I'm no pilot, but I don't see how banked takeoffs and landings are necessarily better than crosswinds. Video here: http://www.bbc.co.uk/news/magazine-39284294

Adipocere · Thu Mar 16, 2017 2:46 am

I think the training requirements for such a circular runway will be significantly different and since not all airports will convert over, won't any such move cause an (unacceptable?) uptick in accidents and incidents until the pilot community's learning curve meets the level of competence and experience with straight line runways?

Channex757 · Thu Mar 16, 2017 2:51 am

It's certainly blue sky thinking. My biggest concerns would be stresses on tyrewalls and undercarriage. Conventional runways allow aircraft to arrive and depart linearly. What would be the problems to be overcome here with moving the aircraft up and down the banked walls? Gravity is working at an angle with the banked wall setup and how would that affect the relatively delicate balance of the wheelsets?

PanzerPowner · Thu Mar 16, 2017 2:53 am

My biggest concern is... how are you supposed LAND?! And I thought Tegucigalpa was a bad idea. This brings in way too many variables that is in a career that has too many variables. Is a plane supposed to hard wing over to land?

AirbusCanada · Thu Mar 16, 2017 3:19 am

Dutch researchers seem to think it's worth exploring.

BBC news video

http://www.bbc.com/news/magazine-39284294

NichCage · Thu Mar 16, 2017 3:29 am

I don't think that this idea will ever come to life. First of all, even if there is benefits to this idea, airports would not spend the money and time to build a circular runway. Along with that, I think passengers would hate landing on a circular runway. Runways need to be in a straight line, not in a circle.

jetblastdubai · Thu Mar 16, 2017 3:33 am

Where would the glide slope and localizer antennas go? Solve one problem and a new one arises.

32andBelow · Thu Mar 16, 2017 3:35 am

jetblastdubai wrote:
Where would the glide slope and localizer antennas go? Solve one problem and a new one arises.

Into the dual GPS in the airplane

hoya · Thu Mar 16, 2017 3:52 am

How do you managed missed approaches? Seems like a nightmare for ATC to keep track of so many different planes going in different directions. Also, the banked runways would effectively limit wingspans - yes, gate restrictions exist, but Boeing is introducing a folding wing on the 777s.

Flighty · Thu Mar 16, 2017 3:54 am

How about a spherical runway...

VS11 · Thu Mar 16, 2017 4:10 am

Circular runways existed in the UK. I saw the video but it did not have estimates for the area for such an airport. How would it compare to the size of Heathrow, or ORD for instance?

Jshank83 · Thu Mar 16, 2017 4:16 am

I would imagine if you blew a tire (which would be more likely, but still not common) that you would shoot off the side of it similar to a nascar driver that blows a tire on a turn. Just seems like planes landing gear would all need to be redesigned to work with this setup. It does seem like it would be tough to keep track of what planes are landing/take off where. I am sure it would still have numbered areas though. If one goes long or short does it impede on another plane? The wind thing is great for one plane but what about the other 3 taking off at the same time going totally different directions?

Q · Thu Mar 16, 2017 4:29 am

LOL! I dont think it helps as much circle runway. They would have to put 25 ILS each direction. No ILS lights no visual fogs no visual snowing or rain for circle runway it won't work! How did researchers forgot all about that? LOL!

Q

Q · Thu Mar 16, 2017 4:32 am

Jshank83 wrote:
I would imagine if you blew a tire (which would be more likely, but still not common) that you would shoot off the side of it similar to a nascar driver that blows a tire on a turn. Just seems like planes landing gear would all need to be redesigned to work with this setup. It does seem like it would be tough to keep track of what planes are landing/take off where. I am sure it would still have numbered areas though. If one goes long or short does it impede on another plane? The wind thing is great for one plane but what about the other 3 taking off at the same time going totally different directions?

Good point!!! Must be straight runway if blew or burst tires. You were right I can see racing cars burst tires lost control when curve turning. No way for the plane. FAA would telling to the researchers to stop action study and move ahead. It should be banned and avoid it right now.

Q

aklrno · Thu Mar 16, 2017 4:44 am

Did this article appear about 2 weeks ahead of schedule?

MesserJ · Thu Mar 16, 2017 5:10 am

The standard straight, flat runway just seems a lot safer and more practical to me.

adamblang · Thu Mar 16, 2017 5:31 am

It's enough of a fight for a pilot to land flat, managing two dimensions, in good weather. (Wind gusts, pilot compensates, and you're just a smidge further down a straight line.) Having to land curved, managing three dimensions, will make safety that much more difficult. (Wing gusts, pilot compensates, and you're off in a field.)

And that banking! Let's bring the pavement closer to the wings and engine, giving the pilots less space to play with during cross winds. Great idea!

The goal of new aviation technology is to improve safety, not diminish it.

aerolimani · Thu Mar 16, 2017 5:33 am

On a banked corner, the passenger would not feel anything all that different for what they experience when a plane turns in the air; the feeling of being pushed down into your seat.

As to ILS, for the times you might need it, I would think that capability for ILS approaches from 6 directions would be more than sufficient. They say this system is capable of replacing 4 runways, so this is not outrageous.

Of course, there are still a myriad of other technical issues, as others have already posted. But, with continuing modernization of ATC, perhaps in the future, a system such as this isn't so crazy.

An interesting aspect of the concept is how the aircraft landing, rounding a banked corner, would be pressed down into the runway by the centrifugal force. This would significantly increase the effectiveness of braking. Less reverse thrust would mean less noise and fuel burn.

Edit: For the record, I'm not saying I think this is a practical, achievable idea. However, from an intellectual viewpoint, it provides interesting food for thought.

doug_or · Thu Mar 16, 2017 5:34 am

Just takeoff and land from treadmills and be done with it.

VirginFlyer · Thu Mar 16, 2017 6:05 am

doug_or wrote:
Just takeoff and land from treadmills and be done with it.

How many birds will they be able to fit inside the aircraft?

V/F

Mir · Thu Mar 16, 2017 6:17 am

I don't see how this does anything but reduce capacity in high winds. You'd be basically down to the capacity of one runway while taking up the sort of space in which you could fit three or four conventional runways. Dealing with wake turbulence would also be quite difficult with all the crossing flight paths.

aerolimani wrote:
An interesting aspect of the concept is how the aircraft landing, rounding a banked corner, would be pressed down into the runway by the centrifugal force. This would significantly increase the effectiveness of braking. Less reverse thrust would mean less noise and fuel burn.

Idle-only reverse is already a thing at a lot of airports. You wouldn't really be gaining anything.

c933103 · Thu Mar 16, 2017 6:42 am

hoya wrote:
How do you managed missed approaches? Seems like a nightmare for ATC to keep track of so many different planes going in different directions. Also, the banked runways would effectively limit wingspans - yes, gate restrictions exist, but Boeing is introducing a folding wing on the 777s.

Is it possible for missed approach to happen in circular runway? As the runway length shall be infinite...

aerolimani · Thu Mar 16, 2017 6:47 am

Mir wrote:
aerolimani wrote:
An interesting aspect of the concept is how the aircraft landing, rounding a banked corner, would be pressed down into the runway by the centrifugal force. This would significantly increase the effectiveness of braking. Less reverse thrust would mean less noise and fuel burn.

Idle-only reverse is already a thing at a lot of airports. You wouldn't really be gaining anything.

Sure you would gain. With improved braking effectiveness, aircraft could vacate the runway more quickly, and braking would be better in poor conditions. I'm not saying that's good enough reason to validate the concept, but you can't say that improved braking effectiveness wouldn't have its benefits.

neutrino · Thu Mar 16, 2017 6:52 am

VirginFlyer wrote:
doug_or wrote:
Just takeoff and land from treadmills and be done with it.

How many birds will they be able to fit inside the aircraft?

V/F

Don't know about the avian flock but probably many thousands of squirrels.

LupineChemist · Thu Mar 16, 2017 8:55 am

Yeah, it's an interesting mental exercise for when everything works right.

Gear collapse on landing or a belly landing? Now you're off the high end of the bank at high speed and a bad situation just got a whole lot worse.

As was already mentioned, a blown tire could have similar results.

On the interesting side, it would eliminate the whole idea of V1 since there's always more runway.

Dardania · Thu Mar 16, 2017 9:19 am

LupineChemist wrote:

On the interesting side, it would eliminate the whole idea of V1 since there's always more runway.

Probably still have wheel speed limits to contend with...

With the burst wheel scenario, if the outer lip of the doughnut were ramped...maybe that would naturally bring any plane back to centre-line (ish)

If the bank angle of the runway were matched to the radius of the curve, maybe there would be no appreciable feeling of centripetal force in use...

USAirKid · Thu Mar 16, 2017 9:45 am

This is fascinating, but I'd like to see thoughts on a few things which don't seem to be addressed in the video:

They state that the circular runway can handle the traffic of four linear runways. What happens when you need capacity for a fifth?
If there is an accident/incident that takes time to clear from the runway, does the remainder of the runway remain usable? With linear runways there can be a crashed plane on one runway, and the others will remain in service. (After firefighting service capacity is returned to its necessary level.)
It seems like there would be difficulties and excess risk if one airplane "overruns" into a segment of the runway that has been reserved for another airplane.
Doesn't this just push the crosswind problem around? if a plane is using 1/3 of the runway there likely is a part of its operation that'll be subject to a crosswind.
Does this limit how much an airport can expand? Once you've filled the middle of the runway what is left?

This is a lot to cover in a three minute video, but I'm really interested in all of the contingency planning that is involved.

Amiga500 · Thu Mar 16, 2017 1:24 pm

AirbusCanada wrote:
Dutch researchers seem to think it's worth exploring.

They must have been on drugs when they came up with it.

They must also have an allergic reaction to numbers.

So, runway diameter of 3.5 km or so?

Lets say the aircraft takeoff and land at 160 kts. Thats ~80 m/s. (It actually won't be that, it'll be nearly 1.1x that to account for the additional g loading )

V^2/R ~ 3.9 m/s^2

atan(3.9/9.81) = 21.5degrees.

21 point f**king 5 degrees (25.5deg if you account for the additional g loading). It beggars belief that the NLR are allowing this idiot in the door never mind allowing him to use simulators.

For 2 points of reference:

(1) Alp D'Huez, one of the most famous climbing stages on the cycling calendar, has an incline of between 9-11%. That is between 4.5 - 6.3 degrees.
(2) The bank angles at the Indy motor speed way are ~9deg.

So this clueless clown is proposing we build runways with bank angles steeper than 3x Alp D'Huez and 2x the Indianapolis speedway banks.

Mental. Utterly mental.

BerenErchamion · Thu Mar 16, 2017 1:51 pm

So much "I don't understand how it works, therefore it's a stupid idea" in here.

Maybe it is a bad idea. On the other hand, I doubt the people who came up with this are idiots unfamiliar with aviation--unless you've read the report (the actual research report, not the distillation into a video for mass media consumption), you can't just assume they haven't already thought of and come up with creative solutions to the problems you are perceiving--or have reasons to think that they're not actually problems at all.

blockski · Thu Mar 16, 2017 1:57 pm

Amiga500 wrote:

For 2 points of reference:

(1) Alp D'Huez, one of the most famous climbing stages on the cycling calendar, has an incline of between 9-11%. That is between 4.5 - 6.3 degrees.
(2) The bank angles at the Indy motor speed way are ~9deg.

So this clueless clown is proposing we build runways with bank angles steeper than 3x Alp D'Huez and 2x the Indianapolis speedway banks.

Mental. Utterly mental.

I would note that the Indianapolis Motor Speedway is a pretty flat track. https://en.wikipedia.org/wiki/Oval_trac ... g_and_size

Lots of the NASCAR tracks have their curves banked in excess of 30 degrees.

atul1 · Thu Mar 16, 2017 2:13 pm

I wonder how would passengers feel during take off rolls. I'm not sure about others, but I'd certainly throw out!

BaconButty · Thu Mar 16, 2017 2:35 pm

I'd recommend a look at this url http://www.endlessrunway-project.eu/documents/index.php
Especially the aircraft characteristics document. I'm trying to make sense of it myself now.

This may not be a go-er but they've done their homework.

dtw2hyd · Thu Mar 16, 2017 2:45 pm

c933103 wrote:
hoya wrote:
How do you managed missed approaches? Seems like a nightmare for ATC to keep track of so many different planes going in different directions. Also, the banked runways would effectively limit wingspans - yes, gate restrictions exist, but Boeing is introducing a folding wing on the 777s.

Is it possible for missed approach to happen in circular runway? As the runway length shall be infinite...

The runway length is infinite, but not the landing zone for any approach. Also a portion of circular runway will always have cross winds. It might have worked with 1960 tail draggers, but I don't see it happening with current jets.

Circular runway may take little area, but you have to create 5 mile radius buffer zone for runway excursions. No one want to live close to such airport.

They are not talking about reducing the noise, circular runway going to spread the noise to every one. Now only few neighborhoods fight airport development, with this whole cities will object.

113312 · Thu Mar 16, 2017 4:04 pm

Whoever came up with this idea has no concept of the physics. Taking off or landing in a bank would increase the stall speed and effective weight vector. While a high banked track works well for high traction four wheeled vehicles designed with negative lift, all of the advantages are lost for an aircraft. The idea of a curved runway dates back many decades to a time when aircraft had to be able to lift off in 1000 feet or less.

readytotaxi · Thu Mar 16, 2017 4:48 pm

MesserJ wrote:
The standard straight, flat runway just seems a lot safer and more practical to me.

"FLAT?" guess you have not been to BHX

https://www.youtube.com/watch?v=7P9OAng32F0

Cactus105 · Thu Mar 16, 2017 4:49 pm

113312 wrote:
Whoever came up with this idea has no concept of the physics. Taking off or landing in a bank would increase the stall speed and effective weight vector. While a high banked track works well for high traction four wheeled vehicles designed with negative lift, all of the advantages are lost for an aircraft. The idea of a curved runway dates back many decades to a time when aircraft had to be able to lift off in 1000 feet or less.

Yes. I like the way you think.

What happens on a windy day? Land With a headwind, then you have a right or left quartering headwind (depending on which side of the circle you landed n.. which brings up the point: Which way would be standard direction? Northerly winds call for a northerly landing/takeoff obviously, but would you land on the east or west side of the circle?

I guess it all depends on the size oz this thing, as to whether or not you would end your rollout with a direct crosswind or even a tailwind (after landing into the wind).

Another thought/question would be: Obvioulsy we prefer to takeoff into the wind, does that mean we start the takeoff roll with a cross wind and go around the "track" until we have a headwind? Who knows. Lots more PERF calculations!

flyboy730 · Thu Mar 16, 2017 4:54 pm

We sometimes have Vr speeds in excess of 160 knots and takeoff runs near 6,000 feet. I can only imagine the how fun it would be barreling down the runway with a strong, consistently changing wind all while steering the aircraft on the circular runway.

AeroTyke · Thu Mar 16, 2017 5:03 pm

How does the plane get up onto the banking to take off? One minute you're driving your plane along at a decent pace on the flat, then suddennly you're faced with a steep hill in front of you which you need to power up and swing your plane round on. Also at that kind of angle as illustrated in the video, wouldn't the plane tip sideways onto its wing tip? All the pax would be leaning to the side until it reaches a certain speed on the take off roll too.

Also how would ATC know where to put them on the loop to start their take off roll? ATC would need to have them airborne at a certain point so that when they lift off they are heading x degrees and not y degrees about to have a head on with a plane coming in to land. Add in some wind gusts either increasing or decreasing the length of the expected take off roll and ATC has a nightmare on their hands.

It's a stupid April 1st idea and will never see the light of day.

SomebodyInTLS · Thu Mar 16, 2017 5:19 pm

Dare I say it...?

This seems ideal for pilotless aircraft - they won't be fazed by the "weirdness" of it all. They will know exactly what speed and angle to be aiming for at every point ('cause it's all maths, of course).

To tackle some of the other objections; the passengers and gear won't be feeling anything since that's the point of the bank. And on the subject of bank angle, it would be variable camber - so you'd start off horizontal and move outwards as speed increases. Given the diameter of the track I don't expect it to be too hazardous wrt. unsticking and sticking the aircraft. Again, computer control of the whole process (including marshalling all the aircraft to constantly sequence all the takeoffs and landings) would make the whole thing pretty efficient and drama-free, I think.

I have yet to read the NLR document, but I imagine that for piloted aircraft you would be following a precise course already mapped out for you. The NLR are the Dutch NASA, by the way, so don't underestimate them.

zrh177 · Thu Mar 16, 2017 5:48 pm

Don't reinvent the wheel

dtw2hyd · Thu Mar 16, 2017 5:53 pm

Looks like multi $Million EU funded study failed to answer some common sense questions. He seems to have lot of monitors, did he even try on a simulator.

What happens if nose gear doesn't extend or loss of seering , go into one of the happy neighborhoods.

BerenErchamion · Thu Mar 16, 2017 5:55 pm

dtw2hyd wrote:
Looks like multi $Million EU funded study failed to answer some common sense questions.

How do you know? Because you saw a 3-minute video that was distilled and packaged for mass consumption?

Don't make assumptions about what the people doing the study did or did not think of until you've read the report.

Aesma · Thu Mar 16, 2017 5:58 pm

Seems like someone has too much time on his hands !

Even if you overcome the technical problems, the safety of this setup seems horrid. Lose control and instead of plowing to the side or the end of a flat runway, you're now shot up in the air and end up crashed into a terminal !

dtw2hyd · Thu Mar 16, 2017 6:19 pm

BerenErchamion wrote:
Don't make assumptions about what the people doing the study did or did not think of until you've read the report.

Don't create a problem and fix it because some is funding. Is finding 3 mile straight patch of land a problem? Then there shouldn't be any roads or rail road tracks. Those are taking lot of space in busy neighborhoods.

Even roundabouts have entry/exit points. This is not a landing, this is like interjecting a satellite into an tiny orbit with gravity and atmosphere. Most will crash in the center or shootout and crash in the neighborhood.

If neighborhoods are complaining about noise, move the airport. Most congested airports are congested because of transit passengers not O&D.

In old days cities used to fight not to have highway/railroad going close to their city, because they didn't want hobos wandering around their neighborhoods. Now cities want people from all over world pass thru their airport, and very proud of it.

PerfectGriffin · Thu Mar 16, 2017 6:48 pm

I don't really see the benefits of this. Plus a circular runway would constrict any further expansion to the airport.

frmrCapCadet · Thu Mar 16, 2017 6:51 pm

For a lot less money the already progressing technical fix of automated, all weather landing on linear runways is happening.

aerolimani · Thu Mar 16, 2017 7:06 pm

There is a strong tendency I've noticed for a.netters to analyze everything like an engineer; in a very linear fashion. Some money does need to be spent exploring wild possibilities. Until you go down a road, you don't know where it leads. The world needs people who think and work like scientists and artists. Most world-altering breakthroughs happen because of lateral thinking. Even if an idea like this turns out to be unfeasible, that doesn't mean there aren't some important and useful discoveries made.

So… instead of being harsh and dismissive, spending time and energy telling us all why it would never work, why not spend some time wondering what useful discoveries might come out of this.

PHBVF · Thu Mar 16, 2017 7:15 pm

The tyre burst is a risk in its own, but how about one of the most important factors in aircraft design: engine failure.
Say you take off "clockwise", with wind initially slightly from the right (would later become headwind).
In case of an engine failure, the right engine would be the critical one due to the wind, but now if on a slope an EF happens on the right engine...
The aircraft would have a rotation to the right + the wind. Might be more difficult to remain control in that manner...

Rajahdhani · Thu Mar 16, 2017 7:27 pm

Umm - what happens if there is asymmetric (or engine failure, or an ingestion requiring engine shut down)? On a 'straight runway', there is less potential for the additional 'stresses' than a 'curved' runway would provide. Too much thrust on one wing, and you 'scrape' the wingtips - if not managed well. Too little thrust on the 'downward slope' and you're angled back to the airport, with a problem.

Alot of work needed before we recreate the wheel...

It certainly would be more efficient that what we have now - when/if possible.

Tugger · Thu Mar 16, 2017 7:31 pm

Just for a visual reference of the likely 22.5° bank of the runway:

Capacity is the real problem to me. You are stuck with "four runway blocks" when building.

Tugg

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