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Thread: Circular runway?

  1. #1
    Senior Member Evan's Avatar
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    Default Circular runway?

    Is this guy nuts?

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

    So many questions arise...

    ~ How does this work with winds?

    ~ How much more workload is involved to stay on centerline on takeoff, especially below minimum control speed?

    ~ How does ILS work, especialiy RWY and ROLLOUT

    ~ Does the bank angle and yaw (as it were) produce uneven lift on takeoff?

    ~ Isn't the out wingtip traveling faster than the inner one?

    ~ What happens when you lift off under lateral centrifugal force?

    ~ What lateral loads would this exert on landing gear and would existing planes need to have redesigned gear to use this?

    ~ How does slick runway contamination affect this?

    ~ What does a runway excursion look like?

    ~ What do you aim for?

    ~ How does the bank angle affect emergency egress on the runway?

    ~ How do you expand runways in the future?

    ~ Would regulators really allow simultaneous operations on one runway, or is that insane?

    Seems like a lot of basic concerns arenot being considered here...

    But hey, no more overruns and no more need for V1...

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    Great questions, but I bet they researched them. Sounds like he's been doing this a while. I'll take a guess at a few.

    How does this work with winds?
    In high winds you set the landing spot which puts the plane directly into the wind, then as you continue to taxi, the wind will blow the plane toward the center.

    Isn't the out wingtip traveling faster than the inner one?
    Doesn't that happen in a cross winds takeoff anyways? (from a windspeed perspective)

    What happens when you lift off under lateral centrifugal force?
    Doesn't something similar happen in takeoff under heavy crosswinds?

    What happens when you lift off under lateral centrifugal force?
    I'm guessing the tilt of the runway is designed to balance the forces near the takeoff speed.

    How do you expand runways in the future?
    Build another non concentric circle.

    Would regulators really allow simultaneous operations on one runway, or is that insane?
    Probably as long as distances are maintained, because it is the length of 3 runways according to the video.

    I do see a problem under high winds though, where they would only be able to land in one spot.

  3. #3
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    ...How does this work with winds?...
    I would think splendidly...with a little planning your take off / touchdown point occurs with no crosswind (except for momentary changes in wind direction).

    Better yet, what if the thing could rotate...like a treadmill?
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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    I'm just a tiny bit skeptical of the "will eliminate tricky landings" part...
    Be alert! America needs more lerts.

    Eric Law

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    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    Is this guy nuts?

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

    So many questions arise...
    I concur it's crazy, BUT it's not ALL bad.

    ~ How does this work with winds? Already stated.

    ~ How much more workload is involved to stay on centerline on takeoff, especially below minimum control speed? How much more workload is there at ATL, DFW, LAX when there are strong crosswinds?

    ~ How does ILS work, especialiy RWY and ROLLOUT ILS is no big deal...we have lots of modern GPS and computer wizardry...plus the vast vast majority of instrument approaches have very decent amounts of visual flight...not everything is CAT IIIc (or whatever it is).

    ~ Does the bank angle and yaw (as it were) produce uneven lift on takeoff? Do cross winds produce uneven lift on takeoff?

    ~ Isn't the out wingtip traveling faster than the inner one? Oh no...planes should never ever turn, lest the outer wingtip uncontrollably rise...

    ~ What happens when you lift off under lateral centrifugal force? What happens when you lift off under a cross wind?

    ~ What lateral loads would this exert on landing gear and would existing planes need to have redesigned gear to use this?...how many times do I have to say "crosswind"

    ~ How does slick runway contamination affect this? Again, landing on a straight runway in a crosswind may provide somewhat similar issues.

    ~ What does a runway excursion look like? Tracked up grass and mud on the underside of the plane and maybe busted runway lights and gear and scrunched underslung engines.

    ~ What do you aim for? The runway...don't mean to be totally dismissive, but I am not sure this is a deal breaker.

    ~ How does the bank angle affect emergency egress on the runway? How does the bank angle affect emergency egress in NASCAR?

    ~ How do you expand runways in the future? Here I agree...it seems to me this limits the amount of pavement for multiple landings and takeoffs and maybe complicates ATC and- if there's multiple operations...you ARE forcing downwind landings (or something strange) to some of the planes...and to me, this is the deal breaker.

    ~ Would regulators really allow simultaneous operations on one runway, or is that insane? As someone already said, I don't think that simultaneous operations are a deal-breaker here...might require some regulation changes, but there's pretty decent traffic separation for modest traffic levels.

    Seems like a lot of basic concerns are not being considered here... Interesting idea, but concur that there's probably a number of issues that keep this from realistically working.

    But hey, no more overruns and no more need for V1... Indeed.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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    Quote Originally Posted by Evan View Post
    ~ How do you expand runways in the future?
    Oh c'mon, that's easy!
    Click image for larger version. 

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    Be alert! America needs more lerts.

    Eric Law

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    Senior Member 3WE's Avatar
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    Quote Originally Posted by elaw View Post
    ...easy!...
    Awesome!
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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    Senior Member 3WE's Avatar
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    Quote Originally Posted by Schwartz View Post
    ...it is the length of 3 runways according to the video...
    Doing some very rough ciphering, you've got a ~2 mile diameter circle.

    To get an airliner to turn in a 1-mile radius requires a pretty decent bank angle (maybe Gabe can give us some specifics).

    Bottom line: It seemed like a nice gradual, 'possible' turn until I thought about it...now I think the turn is steeper and something we probably don't want to do.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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    Senior Member Gabriel's Avatar
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    Quote Originally Posted by 3WE View Post
    Doing some very rough ciphering, you've got a ~2 mile diameter circle.

    To get an airliner to turn in a 1-mile radius requires a pretty decent bank angle (maybe Gabe can give us some specifics).

    Bottom line: It seemed like a nice gradual, 'possible' turn until I thought about it...now I think the turn is steeper and something we probably don't want to do.
    The article says 3.5km=3500m diameter, that's 1750m radius (close to 1 mile as you said, but I will keep it metric).
    The turn radius depends on 2 factors (and I am assuming no wind): TRUE air speed and bank angle (for example a turn at an approach speed of 140 kts IAS and 20 deg of bank, will take a quite bigger radius at La Paz airport in summer at 10000ft and 100 F in the summer than in Seatle at sea level and 20 F in the winter).

    So, for a 1750 radius turn, and no wind, the required bank angle for different TAS would be:

    80 kts ==> 6 deg
    100 kts ==> 9 deg
    120 kts ==> 13 deg
    140 kts ==> 18 deg
    160 kts ==> 23 deg
    180 kts ==> 30 deg

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    Senior Member Evan's Avatar
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    Quote Originally Posted by elaw View Post
    Oh c'mon, that's easy!
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    Hadn't thought of that.

  11. #11
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    The article says 3.5km=3500m diameter, that's 1750m radius (close to 1 mile as you said, but I will keep it metric).
    The turn radius depends on 2 factors (and I am assuming no wind): TRUE air speed and bank angle (for example a turn at an approach speed of 140 kts IAS and 20 deg of bank, will take a quite bigger radius at La Paz airport in summer at 10000ft and 100 F in the summer than in Seatle at sea level and 20 F in the winter).

    So, for a 1750 radius turn, and no wind, the required bank angle for different TAS would be:

    80 kts ==> 6 deg
    100 kts ==> 9 deg
    120 kts ==> 13 deg
    140 kts ==> 18 deg
    160 kts ==> 23 deg
    180 kts ==> 30 deg
    What happens when the right main gear collapses at 140kts on a 20° bank? (moving clockwise)

  12. #12
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    What happens when the right main gear collapses at 140kts on a 20° bank? (moving clockwise)
    Probably something similar to when the shimmy damper fails and the right main gear collapses...scratched up engine nacelles.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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    Senior Member 3WE's Avatar
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    No point in further discussion. The conversion is underway.

    Jetphoto taken 3/16/2017. I am not sure I like the livery. Any other advice in the way of pre screening?


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    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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