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Thread: Lear 35 down approaching Teterboro

  1. #21
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by 3WE View Post
    Pure speculation- I think Gabe may be out of line that the turn needed to be 5 miles out...not sure that's Kosher in the New Yark crowded airspace with airports all over creation...BUT, indeed they waited too long...I was disappointed that Flying did not mention visibility or ceiling- as conceivably, that might force a guy to push it...delays in breaking out and seeing the airport and/or concerns with losing contact while 'circling'.
    What?

    The Runway 6 ILS, circle to Runway 1 is a common approach to TEB, with aircraft normally leaving the localizer at the final approach fix nearly four miles from the end of the runway. In the May 15 accident, the Learjet remained on the localizer until less than a mile from the end of Runway 6 before starting a right turn to land on Runway 1.
    At the time of the accident, winds were reported as 320 at 20 knots gusting to 30, a few scattered clouds at 4,500 feet and visibility of more than 10 miles.
    Guess where that comes from?

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  2. #22
    Senior Member Gabriel's Avatar
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    Orange and blue lines are 1 NM long. Green turns are 1NM radius. It assumes no wind.
    Typical descent path is about 300 to 350 ft per NM.
    With a plane that approaches at more than 100 kts, there's no way I am braking off the LOC 06 any closer than 4NM.
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  3. #23
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    Orange and blue lines are 1 NM long. Green turns are 1NM radius. It assumes no wind.
    Typical descent path is about 300 to 350 ft per NM.
    With a plane that approaches at more than 100 kts, there's no way I am braking off the LOC 06 any closer than 4NM.
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    What's the turning radius of a Lear 35 at approach speed in a 90* bank?

  4. #24
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    What's the turning radius of a Lear 35 at approach speed in a 90* bank?
    130 kts is 67 m/s.
    At 90 deg of bank you will not hold the altitude or attitude no matter how much you "pull up" (because "up" is 100% horizontal), but that doesn't prevent you from making the turn, and all the lift will contribute to the radial acceleration needed to bend the speed vector (i.e. turn).
    So let's say that you pull with a load factor of 2.5, that means that the lift will be 2.5 times the weight, and since the lift will be the only horizontal force with a radial component (neglecting an radial component that the thrust may have), we have

    Sum of F radial = 2.5 x weight = m x acc radial
    Since weight = m x g (g = acceleration of the gravity =~ 10 m/s2)
    2.5 x m x g = m x a
    So, a = 2.5 g = 25 m/s2

    Now, in a circular motion, a = V2/r, so r = V2/a = (67 m/s)2 / 25 m/s2 = 179 m = 0.1 NM

    How much with a 30 deg bank turn, assuming we hold the vertical speed constant?

    Well, the vertical component of the lift needs to be equal to the weight.
    The lift vector, tilted 30 degrees from the vertical, will need to measure weight / cos 30 deg.

    1/cos 30 = 1.15 will be the load factor (and, if you are interested, the stall speed will be sqrt(1.15) = 1.075 times, or 7.5% faster than, the 1G stall speed). But we are not interested in anything of this.

    The horizontal component of the lift, the one that will make the plane turn, will be lift x sin 30, and since lift was = weight / cos 30, we get that the horizontal component will be weight / cos 30 x sin 30 and that's weight x tan 30 = 0.58 times weight (and remember that weight = m x g).

    Horizontal force = horizontal component of the lift = 0.58 x m x g = m x a
    a = 0.58 g

    a = v2/r

    r = v2/a = (67 m/s)2 / 0.58x10 m/s2 = 773 m or 0.42 NM

    At 15 deg bank it would be 0.9 NM.

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  5. #25
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    Quote Originally Posted by Evan View Post
    What's the turning radius of a Lear 35 at approach speed in a 90* bank?
    Do you mean in the horizontal plane, or the vertical?
    Be alert! America needs more lerts.

    Eric Law

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    Senior Member Evan's Avatar
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    Quote Originally Posted by elaw View Post
    Do you mean in the horizontal plane, or the vertical?
    What's the climbing radius of a Lear 35 in a 90* bank? I guess its an ever tightening... spiral...

  7. #27
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Gabriel View Post
    ...Guess where that comes from?...4 miles...
    LOL- it's beautiful making half-donkey-ass-hat posts after a very quick scan of the flying article, and having Gabe do the deep dive read. I owe you a beer- on my second scan of the article, I did not see ceiling and visibility.

    Seeing that ceiling / visibility is a non issue...I also see that I was right that 5 miles was a bit much since 4 miles is standard...

    OK, good...I get it...the 4 miles (to me) seems like a fat, dumb and happy figure. I am pretty sure I have seen a 3 mile-or-so, near-90-degree base-to-final turn while riding an MD-80, heading West and then South into KKCI...nice gentle bank...plenty of time to straighten it out on final...speed under control...solid airmanship. (Yeah, sure, my foffie side imagined them running a wingtip into the ground...but the reality was Fat, Dumb, Happy, Stabilized).

    So, the guy broke it off 1 mile out...I concur that is too tight. I do still stand by my 'gross deviation from really fundamental fundamentals'...So, maybe it's 1) Don't bank the hell out of a jet (especially down low), and 2) Fast planes will get ahead of you if you are behind. I can't totally discount the wind, but what...without the wind, they would have only needed an 85-degree bank?
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  8. #28
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post

    r = v2/a = (67 m/s)2 / 0.58x10 m/s2 = 773 m or 0.42 NM
    Ok, so, one mile out... .42NM radius turn to the right... .42NM radius turn to the left... nothing a self-respecting cowboy in a hotrod 35 can't handle...

  9. #29
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Evan View Post
    What's the turning radius of a Lear 35 at approach speed in a 90* bank?
    Depends upon how much you pull up relentlessly and how far above maneuvering speed you are.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  10. #30
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    Ok, so, one mile out... .42NM radius turn to the right... .42NM radius turn to the left... nothing a self-respecting cowboy in a hotrod 35 can't handle...
    Cowboys knew their stuff and they were bold and daring but not suicidal. They may try to ride a brave bull in a rodeo, but they would not stay standing in front of a stampede of bulls.

    If this pilot intentionally attempted a say 60 deg bank turn at approach speed and 500 ft, "cowboy" is not the word I'd use. I may use it if he attempted an aileron roll after staying in a shallow climb after take off to gain enough airspeed.

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  11. #31
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by 3WE View Post
    LOL- it's beautiful making half-donkey-ass-hat posts after a very quick scan of the flying article, and having Gabe do the deep dive read. I owe you a beer- on my second scan of the article, I did not see ceiling and visibility.

    Seeing that ceiling / visibility is a non issue...I also see that I was right that 5 miles was a bit much since 4 miles is standard...

    OK, good...I get it...the 4 miles (to me) seems like a fat, dumb and happy figure. I am pretty sure I have seen a 3 mile-or-so, near-90-degree base-to-final turn while riding an MD-80, heading West and then South into KKCI...nice gentle bank...plenty of time to straighten it out on final...speed under control...solid airmanship. (Yeah, sure, my foffie side imagined them running a wingtip into the ground...but the reality was Fat, Dumb, Happy, Stabilized).

    So, the guy broke it off 1 mile out...I concur that is too tight. I do still stand by my 'gross deviation from really fundamental fundamentals'...So, maybe it's 1) Don't bank the hell out of a jet (especially down low), and 2) Fast planes will get ahead of you if you are behind. I can't totally discount the wind, but what...without the wind, they would have only needed an 85-degree bank?
    The problem is that there are miles and miles. If you are approaching 06 and start the right turn 4 miles out, the point where you START THE TURN will be barely 2 and a little miles out of 01. By when you finish the right turn you will be in a 2 miles-out base, then you need to turn 90 deg to the left and you'll line up at about 1.5 miles out with some 500 ft AGL.

    Start right turn the turn 1 mile out of 06 and, if you make it tight, you will be heading directly toward the numbers, but perpendicular to the runway

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  12. #32
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    Ok, so, one mile out... .42NM radius turn to the right... .42NM radius turn to the left... nothing a self-respecting cowboy in a hotrod 35 can't handle...
    Oh, and that's with a 30 deg bank. That's not cowboy worthy. With 90 deg and 2.5G it's 0.1 NM radius.

    Not only that, it doesn't work either. Look at the graph, 1 mile out of 06 means much less than 1 mile out of 01. Even if you could do a 0 radius razor sharp right turn to establish yourself in a 100 deg heading base leg, you would be barely a few feet yards out of 01 by when you intercept the extended centerline of 01 for another zero-radius left turn to final.

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  13. #33
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Gabriel View Post
    ...miles...miles....blah blah blah....miles...miles...mile...blah blah blah...
    Actually, I agree in that with 10 miles visibility, you ought to see the airport, and make nice big fat dumb and happy turns to line up...

    If the winds are severe and/or you cramp yourself a bit and gotta push your bank all the way to 30 degrees as part of cowboy improvisation...well, that's why you get the big bucks and have all the training and take the time to hand fly...and I always thought landing in good gusty winds were about as fun as it got...
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  14. #34
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    What's the climbing radius of a Lear 35 in a 90* bank? I guess its an ever tightening... spiral...
    Bank 90 degrees, pull (or not-pull) zero G, and the plane will describe a nice ballistic parabola (i.e. it will be basically a stone, or better a dart).

    Pull any G that you like other than zero and keep it constant, and that same parabola will be wrapped around a widening cone as the speed builds up.

    Curiosity/Quiz: Once the nose starts going down, if you are pulling up it requires continuous roll input to keep the bank angle at 90 deg, very significant roll input if the nose goes way down. Why?

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  15. #35
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by 3WE View Post
    Actually, I agree in that with 10 miles visibility, you ought to see the airport, and make nice big fat dumb and happy turns to line up...

    If the winds are severe and/or you cramp yourself a bit and gotta push your bank all the way to 30 degrees as part of cowboy improvisation...well, that's why you get the big bucks and have all the training and take the time to hand fly...and I always thought landing in good gusty winds were about as fun as it got...
    Yep. Agreed and concur.

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  16. #36
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Gabriel View Post
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    and

    130 kts is 67 m/s. Sum of F radial = 2.5 x weight = m x acc radial Since weight = m x g (g = acceleration of the gravity =~ 10 m/s2) 2.5 x m x g = m x a So, a = 2.5 g = 25 m/s2, a = V2/r, so r = V2/a = (67 m/s)2 / 25 m/s2 = 179 m = 0.1 NM 1/Cos 30, stall speed will be sqrt(1.15) = 1.075 times, or 7.5% faster than, the 1G stall speed). Horizontal force = horizontal component of the lift = 0.58 x m x g = m x a a = 0.58 g a = v2/r r = v2/a = (67 m/s)2 / 0.58x10 m/s2 = 773 m or 0.42 NM At 15 deg bank 0.9 NM.
    Are you ardvark2zz?
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  17. #37
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    so basically the guy was trying to get a lear 35 at approach speed to act like an SU-35...and paid the ultimate price for his actions.

  18. #38
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by 3WE View Post
    Are you ardvark2zz?
    No. I don't have bunny ears.

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  19. #39
    Senior Member 3WE's Avatar
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    Quote Originally Posted by TeeVee View Post
    so basically the guy was trying to get a lear 35 at approach speed to act like an SU-35...and paid the ultimate price for his actions.
    An SU-35 at a similar bank and altitude might have done the same thing...
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  20. #40
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by 3WE View Post
    An SU-35 at a similar bank and altitude might have done the same thing...
    An Su-35 I don't know, but this Su-27 sliced several heads (but the pilots survived).


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