physics question

Discussion in 'Hangar Talk' started by SixPapaCharlie, Nov 25, 2015.

  1. SixPapaCharlie

    SixPapaCharlie May the force be with you

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    You are flying along in IMC and have a total instrument failure.
    Vacuum pump, electric, and a bird hit the pitot tube. Part of it went into both static ports.

    Fortunately you are flying to a child's birthday party and have a mylar helium filled balloon with you.

    Keeping the balloon centered on the cabin ceiling you should be able to maintain level flight and also determine if your attitude changes correct?

    Ascend, it moves forward. Pitch down, it moves back etc...

    Would it work like that?
     
  2. Gucci Pilot

    Gucci Pilot Pattern Altitude

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    Forgot forward and back due to acceleration and deceleration.
     
  3. OverTQ

    OverTQ Pre-takeoff checklist

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    Nope.
     
  4. JOhnH

    JOhnH Touchdown! Greaser! PoA Supporter

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    Why not?

    Of course, as Gucci said, it would also move due to accel/decel.
     
  5. wrbix

    wrbix Pattern Altitude

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    Are you allowed at children's birthday parties?
     
  6. Jeff Oslick

    Jeff Oslick En-Route

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    This is when you pull up the artificial "panel page" on your portable GPS/Tablet.
     
  7. Matthew

    Matthew Touchdown! Greaser!

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    Or you pull the CAPS handle.
     
  8. PaulS

    PaulS Final Approach

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    You just killed a billion dollar aviation instruments industry.
     
  9. MAKG1

    MAKG1 Touchdown! Greaser!

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    No. It's like trying to fly with a spirit level.

    Level turns don't move it. Poor coordination does. The effects of acceleration will totally screw you up.

    It will naturally drive you into a spiral dive just like trying to fly by feel does.
     
    Last edited: Nov 25, 2015
  10. Checkout_my_Six

    Checkout_my_Six Final Approach

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    birds don't fly in clouds.....impossible hypothetical. :D
     
  11. Pilawt

    Pilawt Final Approach PoA Supporter

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    Do you have a cat in the airplane?
     
  12. Sac Arrow

    Sac Arrow Touchdown! Greaser!

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    Playa fo real
    6PC may be on to something though. I don't think you could maintain level flight on the basis of keeping the balloon centered in its spot in the cockpit, BUT, it would act as sort of a crude "gyro", so you could paint a lubber line circling the balloon and it would act as an independent attitude reference. Because the balloon is tethered, there would be some effect from turns and acceleration, but as long as they are small, it might work adequately.

    If you could untether it and have it float in free space, it might work fairly well.
     
  13. Jeff Oslick

    Jeff Oslick En-Route

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    This would work a lot better in a vacuum.
     
  14. Lindberg

    Lindberg En-Route

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    How would you tell the difference between diving and accelerating straight and level?
     
  15. MikeELP

    MikeELP Pattern Altitude

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    Don't forget the duck!! :D
     
  16. Sac Arrow

    Sac Arrow Touchdown! Greaser!

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    Yes.

    Same way an AI would tell you. Balloon would be sideways in a dive. It would only give you attitude information reliably, to the extent that it isn't upset by contacting the cabin.
     
  17. Norman

    Norman En-Route Gone West

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    If you have all those failures, face facts; it just isn't your day. (Or maybe it's going to be your day.):yikes:
     
  18. MAKG1

    MAKG1 Touchdown! Greaser!

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    Umm, helium doesn't float in a vacuum.
     
  19. exncsurfer

    exncsurfer Pattern Altitude

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    I guess the question is, is it floating relative to earth, or the G force created by the plane(as in a turn)?

    Somebody knows, not me. 6pc, you are just full of these!

    :)
     
  20. SixPapaCharlie

    SixPapaCharlie May the force be with you

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    Sorry I meant untethered.
    Like actually ON the ceiling
     
  21. Graueradler

    Graueradler Pattern Altitude

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    I prefer a 3/4 full mason jar of white lightning. When you can't keep the greasy side down, you can consume the instrument and not care.
     
  22. MAKG1

    MAKG1 Touchdown! Greaser!

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    That's what I thought you meant.

    It's a spirit level.
     
  23. SixPapaCharlie

    SixPapaCharlie May the force be with you

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    But if in flying straight and level the balloon is centered right.
    My goal isn't to navigate anywhere, just keep from spinning it in while I troubleshoot.

    If I start to bank, the balloon would roll the opposite direction. No?
     
  24. Checkout_my_Six

    Checkout_my_Six Final Approach

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    problem is.....the balloon's reference is not earth.....and you'd like to know your position relative to earth....
     
  25. FastEddieB

    FastEddieB Final Approach

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    Have you ever transported helium balloons in a car?

    What happens when you brake or accelerate is quite counterintuitive.
     
  26. flhrci

    flhrci En-Route

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    hate to spoil things, but why can't the pilots of real airplanes just open the aux. static port inside the plane or break the glass? hmmmmm Too simple?
     
  27. Let'sgoflying!

    Let'sgoflying! Touchdown! Greaser! PoA Supporter

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    If you ascend it will grow and maybe burst.
    If you descend it will shrink and maybe fall to the floor, not sure.

    How about just use your stratus/ipad/art horizon? Saves carrying kids around too!
     
  28. kyleb

    kyleb En-Route PoA Supporter

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    A coordinated one g roll would keep the balloon in one place. Bad idea for a backup instrument.
     
  29. PaulS

    PaulS Final Approach

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    Yep, balloon moves forward when you accelerate, back when you brake, my observation anyway.
     
  30. Henning

    Henning Ejection Handle Pulled

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    No, same reason kinestetic senses don't work, the vector angle of gravity is stable in coordinated flight. Your deck angle on climb and descent won't be significant enough to over come the friction of the balloon until the angles are high enough that you're in trouble. Better to get a cat or a duck for emergencies.
     
    Last edited: Nov 25, 2015
  31. JOhnH

    JOhnH Touchdown! Greaser! PoA Supporter

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    Are you sure about that? Or are you thinking about gravity instead of a vacuum?
     
  32. FastEddieB

    FastEddieB Final Approach

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    Mine as well.

    Logical, but not what one expects.
     
  33. Henning

    Henning Ejection Handle Pulled

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    Yep, your car is a big tank filled with fluid that has inertia. The car applies force to the fluid, and the fluid applies force to the balloons. The balloons follow the motion of the fluid and the vortexes from acceleration in a closed system.
     
  34. Captain

    Captain Final Approach

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    It's obvious what happens. Air has mass as pilots are aware.
     
  35. Shawn

    Shawn En-Route

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    What happens if you fill the cat with helium?
     
  36. FastEddieB

    FastEddieB Final Approach

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    It will still land on its feet!
     
  37. kyleb

    kyleb En-Route PoA Supporter

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    Not if you use enough.
     
  38. EdFred

    EdFred Touchdown! Greaser! PoA Supporter

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    To figure this out, ask, "why does helium rise?" Because it's lighter (less dense) than the surrounding air, correct?

    Well, in a vacuum where there would be no air for the helium to be lighter than, it would be the heaviest/most dense thing there, and gravity would bring it to the bottom of the chamber.

    Of course technically as soon as anything is put in the vacuum, it's no longer a vacuum.
     
  39. Henning

    Henning Ejection Handle Pulled

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    Except for Dark Matter.
     
  40. Silvaire

    Silvaire En-Route

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    Helium floats because it's lighter than an equivalent volume of air. If there's no air then what is it lighter than? Of course a Mylar or rubber ballon isn't going to be able to hold it's cookies in a vacuum anyway so the point is moot.