Pilots and plane people, circular banked runways?

[Joeaksa]

In the old days the normal airport was in many cases a piece of dirt or later on hard surface that was 3000-5000 feet square. That way the airplane landed into the wind no matter which direction it was coming. Then land got expensive and they started encroaching on the airports and military bases and it was over.

The circular runway could be a neat idea but think of the stresses it would put on the outer landing gear! Nah, not going to work...

[flipper35]

Originally Posted by red-beard

Nope. Need to re-think that. Lift only has to overcome the weight. The issue is the application of rudder, which might require more thrust.

The real problem with a runway like this is that you want to take-off and land against the wind. Going in a circle you could rapidly gain or lose effective lift as your angle to the wind changes.

Your stall speed increases as bank increases and seeing as you have to be in a coordinated turn on the ground as you take off, takeoff speed increases.

Also, you are flying relative to the wind so whether you turn into or away from the wind "direction" does not matter. Your airspeed is the same.

How do you setup precision approaches? What about visual approaches and VASI? WAAS could help with some of the newer aircraft and ILS approaches, but older stuff wouldn't work very well and your approach would either have to have a large circular approach intersect a smaller circle or a straight in approach that suddenly becomes a circle. How do you setup the transmitters for that? Do you have 360 of them for all approach angles? Then you have effectively one runway now instead of multiple, unless you make multiple circles and then do you make concentric to save land or have them side by side? What if there is a gear issue like the Westwind that had to make an emergency landing in Sarasota? He would have shot off the runway much sooner on a circular runway.

Those are just a few things off the top of my head. I cant think of any advantages.

[BE911SC]

Originally Posted by Seahawk

NAS North Island in the 1930



I was stationed there in the 1980's - things had changed

The large ashpalt circle is what was known as a landing mat and also served navy blimps. Landing mats were often large square areas with painted runways in several directions. Not a circular runway. Just check the windsock and land parallel to the sock, into the wind. (See: Joeaksa above)

Circular runway is a dumb idea. (20,000 hours multi-engine turbojet transport.) (But that may not mean anything.)

[NeedSpace]

Originally Posted by matt930s

Here's a good counterpoint article:

Why the circular runway concept wouldn't work - Business Insider

I don't see how it would ever happen, interesting but can't see it.

Wouldn't another issue be planes landing at the same speed? Wouldn't planes with different landing speeds cause a substantial problem here? While this might not be a big issue at the EWR, LGA and JFKs of the world, most airports allow other smaller craft and not just large jets.

I am also curious about how you would call out your landing? I am landing on runway at 20 degrees? Or maybe you would say runway followed by the number on the compas rose, "Landing on Runway 18" means landing at the most south point I suppose?

It was hard enough for me to learn how to land on center line, couldn't imagine the extra talent needed to land in a circle at an angle!

I hate how true this quote is "So, congratulations, your extra special runway just took on an arrival rate worse than Newark."

[Tervuren]

Originally Posted by svandamme

On a normal runway, if the head wind drops or the rate of descent is variable, or there is poor visibility, low ceiling, at worst you come down 500 meter past the point where you normally touch down.
Still plenty of runway left to stop the plane.


How are they planning to do that on a circular runway?
come out of the low ceiling and then say, aw shucks, i missed my turn
There is less safety margin.

So far you are the first person to raise a legitimate concern in this thread.

The problems that exclude this from use are that of landing.

I find it kinda funny the way certain users try to find non existent problems with take off. Possibly, unlike myself, they've never been to an oval track. Take off is easy.

The only situation I can think of where a run way like this would be useful, is launching heavily fueled long range aircraft from limited spaces. The landing distance required is shorter, so these aircraft could land on straight run ways, but take off from the bank circular. The downside, is the aircraft that would benefit from this, would put serious load on the points of contact.

[flipper35]

Take off is easy. But unless it is a large circle, which would require more land and asphalt than a normal airport with runways 36/18 and 09/27 and say 31/13 your takeoff speed would be higher than normal creating more wear and tear on the gear.

As I mentioned above, there are a multitude of issues for landing.

Wouldn't it be easier to do a train style roundhouse to turn the runways where you need it? That would move all the electrical equipment with it.

Or, simpler yet, stick with a few runways that are pointed to the prevailing winds. Oh wait, we do that now.

[Tervuren]

Originally Posted by flipper35

Take off is easy. But unless it is a large circle, which would require more land and asphalt than a normal airport with runways 36/18 and 09/27 and say 31/13 your takeoff speed would be higher than normal creating more wear and tear on the gear.

Take off speed would not need to be higher, steer against the banking, exit, and you're in the air. You don't have to lift off against the banking, just exit the banking. Use a progressive angle for your banking, it gradually gets steeper, then gradually rolls off to non existence.

Haveing seen karts go flying into the air off the banking of small grass roots oval tracks, take off is easy.

As to run way size, you just go around multiple times. This is useful for a slowly accelerating aircraft. Landing aircraft are lighter, and need less landing distance.

I wouldn't want to have it as my only run way.

[flipper35]

So when your aircraft is taking off and you go from following the banking to going straight you have centripetal force acting against your plane. Now suddenly one wheel is off the pavement causing the remaining main gear to want to do two things. It wants to follow the banking still and it is preventing the aircraft from remaining level. Unless you are already at takeoff speed, then you would just continue your coordinated turn instead of upsetting the aircraft.

That progressive banking will cause more issues than it is worth when it comes time to land.

Most of the race cars that "take off" do not do so in a straight and level manner.

My comment to size was not to give room to generate speed to take off, it is because a small circle will require a steeper bank which will in turn cause the take off speed to increase, unless you want to fly off over the edge and do a barrel roll as you take off . A larger circle will require less banking which would only require a speed near a straight out take off speed.

[Flieger]

[stevej37]

Originally Posted by flipper35

My comment to size was not to give room to generate speed to take off, it is because a small circle will require a steeper bank which will in turn cause the take off speed to increase, unless you want to fly off over the edge and do a barrel roll as you take off . A larger circle will require less banking which would only require a speed near a straight out take off speed.

Denzel could do it!

[dad911]

Originally Posted by Tervuren

Take off speed would not need to be higher, steer against the banking, exit, and you're in the air. You don't have to lift off against the banking, just exit the banking. ....

I believe it would take considerable more power to take off, as there will be more drag (rudder and ailerons)

Doesn't seem like a good idea to me....

[legion]

Seems like this creates six new problems to not really solve one.

[black_falcon]

Originally Posted by legion

Seems like this creates six new problems to not really solve one.

but it's more green!!

Looks like multiple accidents waiting to happen and making landing more stressful/complicated than it already is. No tnx Jeff.

[RF5BPilot]

Landing in a straight line is hard enough on the pilot and landing gear. Trying to set the plane down on a curved, sloped surface makes no sense.

[ted]

On a curved runway I'd like to see the side loads on a 747 heavy jet trying to stay in the circle.
As it struggled to get airborne from V1 to V2 for several hundred feet with the nose wheel off the ground.

Would make landings in fog even more difficult.

Originally Posted by Seahawk

NAS North Island in the 1930

I was stationed there in the 1980's - things had changed

Same here, 80/82 at FACSFAC (Beaver) radar controller.
The offshore W291 warning area schedule and control facility.
Here is how it looked last September.
https://youtu.be/UR04l6sAj64?t=50s

[Tervuren]

Originally Posted by ted

On a curved runway I'd like to see the side loads on a 747 heavy jet trying to stay in the circle.
As it struggled to get airborne from V1 to V2 for several hundred feet with the nose wheel off the ground.

Graduated banking, the side loads remains neutral. As velocity increases, the air craft floats up to steeper banking.

By tuning the steepest part of the banking to the take off speed of a fully loaded air craft on a humid low pressure hot day, there is no need for the aircraft to run several hundred feet with just the nose wheel off the ground. Once the take velocity of the air craft requires steering input to stay in the circle, the aircraft is already at or over take off speed.

The banking is providing a vertical load that is counter acting the lift of the aircraft, the vertical load exceeds 1G, and the wings are providing negative >1G perpendicular to the banking, but not in the vertical axis.

With take off velocity in hand, the pilot either exceeds the velocity the banking holds the air plane neutral, or steers slightly up the banking. Since the banking would gradually diminish past its highest banking, the air plane levels out, the vertical load reduces, the lift > load causes the air plane to fly as it levels.

[DanielDudley]

Just because you can doesn't mean you should.

[flipper35]

Originally Posted by Tervuren

Graduated banking, the side loads remains neutral. As velocity increases, the air craft floats up to steeper banking.

By tuning the steepest part of the banking to the take off speed of a fully loaded air craft on a humid low pressure hot day, there is no need for the aircraft to run several hundred feet with just the nose wheel off the ground. Once the take velocity of the air craft requires steering input to stay in the circle, the aircraft is already at or over take off speed.

The banking is providing a vertical load that is counter acting the lift of the aircraft, the vertical load exceeds 1G, and the wings are providing negative >1G perpendicular to the banking, but not in the vertical axis.

With take off velocity in hand, the pilot either exceeds the velocity the banking holds the air plane neutral, or steers slightly up the banking. Since the banking would gradually diminish past its highest banking, the air plane levels out, the vertical load reduces, the lift > load causes the air plane to fly as it levels.

So which aircraft do you optimize that banking for? Then, if you steer outside the banking, how wide is that skirt outside the banking because you are either still turning as bank decreases creating major side loads on the gear, or you are giving the passengers quite a ride as the aircraft transitions from going around in the bank to straight outside the bank.

On a bank that severe, I would not want to land on it.

[dad911]

Pass out a few more barf bags. Some people can barely handle the straight line acceleration & deceleration.

[Tobra]

I can see few benefits, with many downsides