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-   -   Will circular runways ever take off? (http://www.aviationbanter.com/showthread.php?t=229290)

[email protected] March 16th 17 07:18 PM

Will circular runways ever take off?
 
I saw this story and it reminded me, has anyone ever tried landing on a curved flat road or something similar to a circular runway?

I supposed the banked sides of this concept help.

BBC story "Will circular runways ever take off?"
http://www.bbc.com/news/magazine-39284294

http://www.endlessrunway-project.eu/project/index.php

SAE paper Flight Operations on a Circular Runway
http://papers.sae.org/660283/
Abstract:
Inherent advantages of an infinitely long runway, optimum technical location at the center of the circle, and safety enhancement by increased directional stability during aircraft ground roll generated interest in the circular runway concept. The Bureau of Naval Weapons originated a project to determine, within the realm of aircraft behavior, the feasibility of flight operations from a circular runway.Utilizing an existing circular track at the General Motors Proving Ground near Mesa, Arizona, tests were conducted with a T28, an A1-E, an A4-B, and a C54. It was determined that pilots readily adapt to operations from a circular runway, that aircraft lateral and directional stability is more positive than on a flat runway, that tangential approaches are no more difficult than approaches to a straight runway, and that low visibility approaches are much simpler than to a straight runway. Flight operations from a circular runway are feasible.


Chris

Matt Herron Jr. March 16th 17 10:16 PM

Will circular runways ever take off?
 
Hmm...interesting idea. first blush thoughts:

headwind changes to a crosswind, changes to a tailwind as you land/take-off?

banked runway means lateral load on the aircraft changes as speed increases, meaning you are slipping or crabbing on the ground?

turning take-off requires higher AOA to produce higher lift in turn? more chance of stall?

Americans don't know haw to drive in a round-about!

the real reason it won't work: drinks slide off the table in 1st class as you taxi to the "threshold".

Bruce Hoult March 16th 17 10:26 PM

Will circular runways ever take off?
 
On Thursday, March 16, 2017 at 9:18:32 PM UTC+3, wrote:
I saw this story and it reminded me, has anyone ever tried landing on a curved flat road or something similar to a circular runway?

I supposed the banked sides of this concept help.

BBC story "Will circular runways ever take off?"
http://www.bbc.com/news/magazine-39284294

http://www.endlessrunway-project.eu/project/index.php

SAE paper Flight Operations on a Circular Runway
http://papers.sae.org/660283/
Abstract:
Inherent advantages of an infinitely long runway, optimum technical location at the center of the circle, and safety enhancement by increased directional stability during aircraft ground roll generated interest in the circular runway concept. The Bureau of Naval Weapons originated a project to determine, within the realm of aircraft behavior, the feasibility of flight operations from a circular runway.Utilizing an existing circular track at the General Motors Proving Ground near Mesa, Arizona, tests were conducted with a T28, an A1-E, an A4-B, and a C54. It was determined that pilots readily adapt to operations from a circular runway, that aircraft lateral and directional stability is more positive than on a flat runway, that tangential approaches are no more difficult than approaches to a straight runway, and that low visibility approaches are much simpler than to a straight runway. Flight operations from a circular runway are feasible.


It's a interesting idea. Would be a very nice solution if a heavily loaded aircraft could do one or two circuits if necessary before lifting off. Helicopters sometimes do this in ground effect inside the boundaries of a field or clearing to get sufficient sped to climb away.

But 3.5 km diameter!! 2400 acres (970 ha) inside the centre line! That's huge. Only the world's biggest airports have a runway longer than 3.5 km, and very few would have runways that long in different directions.

Maybe you could do this to increase the capacity of LAX or LHR or Kingsford Smith, but for most cities it's a vast increase in the area of an airport, and decrease in the flexibility of siting it around hills or suburbs or bodies of water.

2 km diameter or less and you might be talking -- that's exactly half a G lateral acceleration at 250 km/h (1.12 G total loading)

Bruce Hoult March 16th 17 10:44 PM

Will circular runways ever take off?
 
On Friday, March 17, 2017 at 12:16:31 AM UTC+3, Matt Herron Jr. wrote:
Hmm...interesting idea. first blush thoughts:

headwind changes to a crosswind, changes to a tailwind as you land/take-off?

banked runway means lateral load on the aircraft changes as speed increases, meaning you are slipping or crabbing on the ground?


Smoothly increasing bank on the runway so you can start on flat ground at the start of the takeoff and go up the sides as the speed increases, keeping crab at zero.

turning take-off requires higher AOA to produce higher lift in turn? more chance of stall?


Not a lot.

At his suggested size of 3.5 km diameter, total G loading at 250 km/h would be 1.04 G, requiring a 2% higher takeoff speed and a 16 degree banking to be balanced.

At 2 km diameter those figures would be 1.12 G, 6% higher takeoff speed, and 27 degrees of bank.

At a very sporting 1 km diameter the figures would be 1.4 G, 20% higher takeoff speed, and 45 degrees banking.

OK, those all assume a constant 250 km/h, so actually it would be worse than that once you allow for the extra loading of the higher speed.

The suggested 3.5 km diameter is certainly very mild! Just almost impossible to find a site for.

Bruce Hoult March 16th 17 11:26 PM

Will circular runways ever take off?
 
On Friday, March 17, 2017 at 12:44:54 AM UTC+3, Bruce Hoult wrote:
On Friday, March 17, 2017 at 12:16:31 AM UTC+3, Matt Herron Jr. wrote:
Hmm...interesting idea. first blush thoughts:

headwind changes to a crosswind, changes to a tailwind as you land/take-off?

banked runway means lateral load on the aircraft changes as speed increases, meaning you are slipping or crabbing on the ground?


Smoothly increasing bank on the runway so you can start on flat ground at the start of the takeoff and go up the sides as the speed increases, keeping crab at zero.

turning take-off requires higher AOA to produce higher lift in turn? more chance of stall?


Not a lot.

At his suggested size of 3.5 km diameter, total G loading at 250 km/h would be 1.04 G, requiring a 2% higher takeoff speed and a 16 degree banking to be balanced.

At 2 km diameter those figures would be 1.12 G, 6% higher takeoff speed, and 27 degrees of bank.

At a very sporting 1 km diameter the figures would be 1.4 G, 20% higher takeoff speed, and 45 degrees banking.

OK, those all assume a constant 250 km/h, so actually it would be worse than that once you allow for the extra loading of the higher speed.

The suggested 3.5 km diameter is certainly very mild! Just almost impossible to find a site for.


Updated figures, allowing for increased takeoff speed feeding back into G loading and required bank angle..

Assumed straight runway takeoff speed 70 m/s, 252 km/h, 136 knots, 156.5 mph

3500 m diameter, 257 km/h, 1.044 G, 16.6 deg bank
2000 m diameter, 271 km/h, 1.155 G, 30.0 deg bank
1609 m diameter, 285 km/h, 1.276 G, 38.4 deg bank
1414 m diameter, 300 km/h, 1.414 G, 45.0 deg bank
1155 m diameter, 356 km/h, 2.000 G, 60.0 deg bank

The figures head to infinite speed and G at 1000 m diameter.

son_of_flubber March 17th 17 01:38 AM

Will circular runways ever take off?
 
On Thursday, March 16, 2017 at 2:18:32 PM UTC-4, wrote:
has anyone ever tried landing on a curved flat road


I hear that if you need to landout in a field that slopes left to right, you drop the right wingtip a bit during a curving final and then you hold the bank during the curving roll out. The bank keeps the uphill wing tip off the ground until you're stopped.

I've never done it, but the fella that told me this claims that this is the best way to landout in one of our 'better' neighborhood landout fields, and that 'lots of people' have done it in that particular field. As I understand it, you set it up so that at touchdown, you're rolling somewhat uphill and simultaneously across the slope, and you try to stop rolling before you start to roll down hill. I've walked the field and tried to visualize the pattern and the roll out, and it kinda makes sense provided you can also thread your way between a couple of big trees on the leading edge of the field.




[email protected] March 17th 17 02:19 AM

Will circular runways ever take off?
 
Circular runways were tested extensively by NACA in the 50's and 60's. General consensus was that, with training and practice, they worked well but were unforgiving with overshooting or undershooting your final approach.

[email protected] March 17th 17 05:32 PM

Will circular runways ever take off?
 
Just like with U-line control airplanes! Mine was a P-51D with a Cox 0.049...

Sure made this pilot (more of a crasher) dizzy!

WB March 18th 17 01:59 AM

Will circular runways ever take off?
 
On Thursday, March 16, 2017 at 7:38:03 PM UTC-5, son_of_flubber wrote:
On Thursday, March 16, 2017 at 2:18:32 PM UTC-4, wrote:
has anyone ever tried landing on a curved flat road


I hear that if you need to landout in a field that slopes left to right, you drop the right wingtip a bit during a curving final and then you hold the bank during the curving roll out. The bank keeps the uphill wing tip off the ground until you're stopped.

I've never done it, but the fella that told me this claims that this is the best way to landout in one of our 'better' neighborhood landout fields, and that 'lots of people' have done it in that particular field. As I understand it, you set it up so that at touchdown, you're rolling somewhat uphill and simultaneously across the slope, and you try to stop rolling before you start to roll down hill. I've walked the field and tried to visualize the pattern and the roll out, and it kinda makes sense provided you can also thread your way between a couple of big trees on the leading edge of the field.



My very first landout was like that. Landing in a nice long field that had a pronounce slope (except the slope was right to left). Landed diagonally going up the slope, left wing down with some opposite rudder to keep the nose headed uphill. And, yes, the glider did start rollng back down the hill and wheel brake would not hold it. Frantic activity for a second or two as I "bailed out" to stop the glider before it built up speed going backward. Luckily, the glider rolled into a slight hollow that slowed us down while I scrambled out.

Josh Fletcher March 18th 17 01:05 PM

Its a cute concept... But no one has discussed Instrument approaches.

I don't see any aircraft that could do a CAT III Circle approach to auto land while trying to make a banking turn on a sloped runway. Much less a pilot that could shoot a hard IFR approach to mins in windy conditions and then try to transition to a curving and sloping runway.

Then the issue with Takeoffs. The presenter was saying that they could launch 3 aircraft at the same time on one circle runway..... I call BS.... they will never clear 3 aircraft to TO off the same runway at the same time... What happens if someone aborts the TO? What happens if someone has an engine failure/fire at V1 and can not fly the published. Even with multiple parallel runways, ATC does not launch simultaneous departures just for that reason.

I could go on and on about the issues that would need to be addressed that they so conveniently don't talk about... I am sure many of them would be the same issues that caused NASA to drop the project in the 60's

thats my 2 cents
J


BTW... Under VFR... I routinely landed in a circle my Aviat Husky in a field that was to short for straight in landings and takeoffs... so I don't hate the idea, just don't think its practical. Especially for some of todays pilots that have no stick and rudder skills and rely on the automation entirely to much..


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