Effect of Density Altitude on Crosswinds

Discussion in 'Flight Following' started by ebykowsky, Feb 19, 2015.

  1. Silvaire

    Silvaire En-Route

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    You tell us Roscoe. What physical law am I missing that says that the aircraft's ground track cannot be altered or that the heading cannot be held constant when applying the control inputs to enter a slip? Because if you don't turn the nose off the initial heading your ground track is not going to remain the same.

    How about the opposite. You are on final in a crosswind, left aileron, right rudder, tracking the centerline of the runway. You are in a slip, correct? So neutralize the controls, nose still pointed down the runway. Isn't your ground track now going to change as the crosswind causes you to drift to the right of the runway?

    What is it that you two aren't getting here? This is basic stuff.
     
  2. RoscoeT

    RoscoeT Cleared for Takeoff

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    Thousands of aviation youtube sensations and nobody can shoot a video of a proper sideslip it seems.
     
  3. RoscoeT

    RoscoeT Cleared for Takeoff

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    OMG, please send a video of you flying down final in a x-wind, slipped, tracking, and aligned with the runway and then NEUTRALIZE the controls. If you think that your nose will still point down the runway after neutralizing the controls, you are way beyond help here. You will continue to track the runway in a crab, but the nose will sure as hell not point "down the runway". Hint- this means the nose will swing left...which BTW is different from TURNING left.

    BTW, this is the most comprehensible FALSE statement you've made in this whole thread. At least I understand where your failings stem from.
     
  4. Silvaire

    Silvaire En-Route

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    That's your answer?

    When I was a kid my instructor had two basic coordination exercises that I practiced involving slips.

    The first one was to slowly move the stick from neutral all the way to the left, back to neutral then all the way to the right while simultaneously applying opposite rudder to keep the compass heading constant. The result is a slip to the left and a slip to the right. No turning involved.

    The second was the same only leading with the rudder, turning the nose off heading and using the ailerons to maintain my ground track over a straight road.

    In both cases you end up with opposite aileron and rudder inputs so you tell me why one condition would be different from the other? They were both slips, the only difference being the ground track and, as I've said, there is nothing physically tethering you to the ground. I don't know why you guys seem to be hung up on that.

    The other disarming thing about these discussions is that some of you are apparently incapable of grasping the concept without a YouTube video. :rolleyes:
     
  5. RoscoeT

    RoscoeT Cleared for Takeoff

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    Dude, stop the unintelligible jabbering and go take your Luscombe or whatever you fly (you are a pilot right??) and replicate these actions PRECISELY AS YOU DESCRIBED THEM, and I quote:

    "You are on final in a crosswind, left aileron, right rudder, tracking the centerline of the runway. You are in a slip, correct? So neutralize the controls."

    Neutralize simultaneously. No centering the ailerons first and skidding the nose to the right.

    Now... I beg you, plead with you for the love of godamighty, tell us what the nose does.
     
    Last edited: Feb 23, 2015
  6. Silvaire

    Silvaire En-Route

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    Maintain heading

    Can you acknowledge that you can enter a slip without changing your heading which will result in a change to your ground track? Without turning?
     
    Last edited: Feb 24, 2015
  7. RoscoeT

    RoscoeT Cleared for Takeoff

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    Nope. If you actually read carefully anything I wrote, you would see that I admit you can do a slipping turn to a very small flight path change (maybe 10-15 degrees) while keeping the nose aligned. Now please read the next sentence with as much care as you can muster:

    But if you continue to hold the exact inputs that caused you to depart your flight path, that you would continue to turn, and your heading (nose) would show a change (continued turn) once you went beyond about 15 degrees from your original flight path and were no longer able to disguise the initial small turn with rudder. You would need to STOP the slipping turn before you reached this point. You are still turning, slipping or no slip. You will never understand this it seems. So...

    Again, please stop babbling and just go do it. Anyone smart enough to get an airplane off the ground should be smart enough to take some video of what they are doing. Until that time, I guess you win because you say so...on the internet. Damn, we've gone in more circles than the Daytona 500. Though this has been more entertaining. I appreciate it.
     
    Last edited: Feb 23, 2015
  8. Silvaire

    Silvaire En-Route

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    Okay, that's all I wanted to hear LoL but apparently a video is the only thing that will convince you - so be it. I'll do that at my soonest opportunity.

    Meanwhile at least I have Wikipedia on my side: :rolleyes: (I know...internet)

     
  9. RoscoeT

    RoscoeT Cleared for Takeoff

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    I have scoured youtube for videos of this mythical sideslip as described in this thread. It seems I'll have better luck looking for bigfoot in my backyard or the Loch Ness monster in the neighborhood swimming pool. Bueller, Bueller?? Nevermind- there's an entry on Wikipedia, last edited by Joe Bloe.
     
  10. Silvaire

    Silvaire En-Route

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    Other option is you could go up and do as described - cross controls without letting heading change - and show us how you'll go around in a circle. :dunno:
     
  11. RoscoeT

    RoscoeT Cleared for Takeoff

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    :rolleyes2:
     
  12. vintage cessna

    vintage cessna Cleared for Takeoff

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    Why can't the heading be held? Do you have a source to reference that describes slips the way you do?
     
  13. RoscoeT

    RoscoeT Cleared for Takeoff

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    It can if you stop the slipping turn after a small flight path change and then continue on a straight slipping non-turning path. Crap, I keep writing as if people actually make an effort to READ. But as I posted in another thread, this is nothing but folks spinning comments attempting to prove others have no grasp of physics. Nothing more that can be done. It's been fun, but it's getting old. Keep spinning if y'all want. Ciao.
     
  14. vintage cessna

    vintage cessna Cleared for Takeoff

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    Let me see of I have this right, and we'll say there is zero wind. The aircraft is cross controlled and that begins a slipping turn. You stop the slipping turn ( I'm not sure how that is accomplished yet) and you find yourself displaced from the original flight path. On the new flight path you can slip straight ahead. Since you are slipping straight ahead and not turning you can remain on the new flight path. In a cross wind landing, how would this compensate for drift?
     
  15. CharlieTango

    CharlieTango Line Up and Wait

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    Once you are off the centerline you can recapture it with 2 slipping turns.

    When not turning the yaw offsets the bank and not turn, to make the small turn add or subtract some aileron while keeping the nose down the runway. It feels like you are drifting sideways that is why we believed you could drift sideways.
     
  16. vintage cessna

    vintage cessna Cleared for Takeoff

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    So, IOW's , if one were to try to hold a slip on final, there is really no point in that because it doesn't stop the drift. You will continually need to make slipping turns to maintain track. So I assume when you finally will land, just before touchdown, you need to make a slipping turn into the wind?

    I'm not necessarily saying this is wrong, but the only source that I have checked,the FAA Airplane Flying Handbook, says that in a slip there is forward movement as well as movement in the direction of the slip, and there is no turn. Do you have another source you could refer me to that describes it the way you do?
     
  17. vintage cessna

    vintage cessna Cleared for Takeoff

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    A“
    sideslip
    ” is entered by lowering a wing and applying
    just enough opposite rudder to prevent a turn. In a
    sideslip, the airplane’s longitudinal axis remains par-
    allel to the original flightpath, but the airplane no
    longer flies straight ahead. Instead the horizontal
    component of wing lift forces the airplane also to
    move somewhat sideways toward the low wing.
    [Figure 8-12] The amount of slip, and therefore the
    rate of sideward movement, is determined by the bank
    angle. The steeper the bank—the greater the degree of
    slip. As bank angle is increased, however, additional
    opposite rudder is
    required to prevent turning.

    That is from the FAA Airplane Flying Handbook. Is that just a bunch of bologna?
     
  18. CharlieTango

    CharlieTango Line Up and Wait

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    My source is this thread, once presented with the correct take it became obvious.

    No you don't have to do any additional turns once established on the centerline in the slip, except in the real world where crosswinds tend to come with shear and you will have to do 2 more little turns after you loose the center-line due to shear or judgement.
     
  19. vintage cessna

    vintage cessna Cleared for Takeoff

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    I might also add that the flight control surfaces become less effective as you slow, so that would require adjustment also.
     
  20. CharlieTango

    CharlieTango Line Up and Wait

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    This could be a balance thing, you have enough aileron to counter the rudder and maintain the 'heading' and as you slow both aileron and rudder loose effectiveness and the balance could be naturally maintained :dunno:
     
  21. vintage cessna

    vintage cessna Cleared for Takeoff

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    I know, and it will work out provided the wind has also diminished as you slow. If the wind hasn't also decreased it may require more control input.
     
  22. vintage cessna

    vintage cessna Cleared for Takeoff

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    You fly a CT, right? I haven't flown a CT , but the other LSA's I have flown slow down at a very fast rate when you start to raise the nose on landing. To the point that even if the wind has diminished somewhat just above the runway you often need to increase control input to prevent drift.
     
  23. Vance Breese

    Vance Breese Line Up and Wait

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    I feel that may be a mistake.
    I have carefully read 382 posts and feel that most of the disagreement is about semantics or perspective.
    In my opinion the way to avoid a debate about semantics is to define the terms in the beginning and stick to those definitions.
    I feel that more people have read the FAA flying handbook than this thread so the FAA flying handbook would probably be a better source of definitions to avoid future misunderstandings.
     
  24. CharlieTango

    CharlieTango Line Up and Wait

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    Yes my CT runs out of energy very rapidly but running out of energy doesn't change my ground track it just makes me land.

    I think less drift due to gradient will cause a need to adjust (small slipping turn).
     
  25. CharlieTango

    CharlieTango Line Up and Wait

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    The obvious problem here is the flying handbook chooses to describe side slips as thought the plane can fly sideways. It works in terms of using aileron to control drift and rudder to control heading but it isn't precisely correct.
     
  26. vintage cessna

    vintage cessna Cleared for Takeoff

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    The obvious problem is you choose not to believe the plain language of the AFH. That is perfectly alright with me. I would just like to know that if the plane is not moving sideways in a slip and you are not turning, how in the world would a slip compensate for drift?
     
  27. Silvaire

    Silvaire En-Route

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    I don't want to step back into this but I'll repeat one thing: look at your turn indicator when you are in a slip, if you were turning the rate gyro would indicate that.
     
  28. whifferdill

    whifferdill Line Up and Wait

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    It doesn't. Flight path cancels drift, slip simply makes for a smoother touchdown. It truly is that simple. You are cancelling drift while crabbing down final in coordinated flight, tracking the runway. If you're drifting downwind, then you need to adjust your flight path more into the wind by turning. Then if you slip, you are only yawing the nose to make the landing smoother, not adding any additional "drift cancelling" forces. That opposite aileron in the slip only keeps the airplane from turning downwind due to the rudder input, not to "fight the x-wind". If you skidded the airplane with rudder alone, the airplane would turn in that direction, wind or no wind. If you are slipping and drifting downwind, then you need to turn the airplane's flight path more into the wind to cancel drift, not try to slip "harder".

    I don't suppose we're making any progress? We were able to help Charlie Tango in this thread after a long discussion. Do you still think I'm flat wrong, or are we just saying the same thing in a different way such that neither of us understand each other?
     
    Last edited: Feb 24, 2015
  29. Silvaire

    Silvaire En-Route

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    That sounds good wiff but you wouldn't be on that flight path with the nose pointed in that direction if the slip weren't cancelling the drift. Look at your airplane doing a no wind forward slip to landing to lose altitude. The airplane is flying laterally in reference to the longitudinal axis, a yaw string tells you that, the wind on the side of your face tells you that. In a crosswind you have the exact same control inputs with the exact same results.

    Seeing that apparently none of us have crashed yet I suppose that's the best answer we're gonna get out of this thread. ;)
     
  30. whifferdill

    whifferdill Line Up and Wait

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    Did you see my video where I went from coordinated flight, then slipped left and right with no flight path change? It made no difference that it was done in no wind. If I'm crabbed in a x-wind, flight path tracking the runway, and then slip without changing my flight path, how can you say that the slip is now the reason for my flight path? How does the slip all of a sudden cancel drift when a slip doesn't change your flight path, and I was cancelling drift before the slip? OK, no progress. Question asked and answered. That's all I came back here looking for. Smooth landings - :cheerswine:
     
  31. Vance Breese

    Vance Breese Line Up and Wait

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    Are you suggesting that an airplane can only fly in the direction it is pointed?
     
    Last edited: Feb 24, 2015
  32. CharlieTango

    CharlieTango Line Up and Wait

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    The slip compensates for drift the same way a crab does. You slip/crab on a heading that produces a ground track that is similar to the runway's (extended) center-line.
     
  33. vintage cessna

    vintage cessna Cleared for Takeoff

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    I have understood everything you have said. The problem with you theory is, when it comes time to land. If you straighten out the nose with rudder, and as you say aileron doesn't prevent or compensate for drift, then you wil land with some drift and side load. I suppose if you did this at the last moment the drift wouldn't be much and the landing would be acceptable.
     
  34. vintage cessna

    vintage cessna Cleared for Takeoff

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    What you are saying doesn't make any sense. In a slip the nose is aligned with the runway heading regardless of wind direction. In a crab your heading is to the left or right of RWY heading.

    If in a slip and the nose aligned with the RWY, if the plane does not have a sideways movement, how would it not drift off course in a cross wind?
     
  35. FlySince9

    FlySince9 Pattern Altitude

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    Oh don't stop now! :stirpot:
     
  36. whifferdill

    whifferdill Line Up and Wait

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    If you crab down final and do nothing but straighten with rudder (no aileron, no slip), then you will start a slow turn in the direction of your rudder input, not drift due to the x-wind. There's a difference between turn and drift. Go up in your airplane and apply rudder while keeping the wings level with aileron. No need for wind. The airplane will start a slow, inefficient, and constant skidded turn. Same thing happens when you straighten out in a x-wind with rudder only. It is NOT the x-wind that starts moving you off runway track, assuming you were previously tracking properly in a crab.

    And yeah, if you time it right, you can skid to straighten out the x-wind landing and touch down before the airplane has turned a significant amount away from the runway track. Some people land this way, though it's much easier in trikes than in tailwheel airplanes. It is literally "crab and kick", rather than "crab and slip".
     
    Last edited: Feb 24, 2015
  37. CharlieTango

    CharlieTango Line Up and Wait

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    You can yaw but that is an attitude change, to change your flight path you have to do a turn. To begin and end a drift 2 turns are required flying sideways is what it seems like, a visual illusion.

    Look at this drift to centerline and notice the 2 turns in the ground track. If you add the turns to the drift between it seems like flying sideways but it isn't, planes need to turn twice they can't correct drift by flying sideways.

    [​IMG]
     
  38. vintage cessna

    vintage cessna Cleared for Takeoff

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    If you come out of the crab and then slip, and the slip does not compensate for drift, how would you remain on the same flight path? Are you relying on intertia?

    Why not just come out of the crab wings level? You can do that in a manner that doesn't swing the nose around to the right.
     
  39. CharlieTango

    CharlieTango Line Up and Wait

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    it doesn't drift off course because the drift is compensated for by a flight path that produces a ground track that is similar to the runway center-line.

    On one hand the you and the air mass are drifting across the runway but on the other hand your flight path is into the crosswind enough to cancel that. The icing on the cake is the sideways attitude that causes the gear to align (rudder authority permitting).
     
  40. vintage cessna

    vintage cessna Cleared for Takeoff

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    I'm going to get a visit from the SPCA for beating a dead horse here. I can tell you this, the FAA Airplane Flying Handbook has been around for a long time. I have never seen anyone challenge the basics that are in that book until I visited this forum. In the end it doesn't really matter as long as the right control inputs are used.