sky12345

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Posts posted by sky12345

  1. >the horizontal component of velocity does have an effect on the vertical component of drag and the vertical component of velocity does have an effect on the horizontal component of drag.

    nonsense,, tautology,, pseudoscience....your pick :D
    its like saying that if we have a triangle with sides a b c and we blow it up 2x the increase of length of a has an effect on length of c!
    thats bs,, no causality whatsoever,, the reason c became 2x is not because a or b became 2x, its because we blew the whole triangle up 2x!
    same here,, as pchapman perfectly explained, greater velocity = greater drag (in quadratic proportion), and its vertical component is greater than when the object is dropped with no horizontal speed
    total velocity is the primary thing, the cause of the effect,, not some mysterious crossbreeding btw horiz and vert components lol
    components r arbitrary imaginary things
    velocity is a real one

    u saying that horiz component of speed has "an effect" on vert comp of drag is like saying that the growing child became taller because the height from crotch to floor increased! lol

  2. sjc

    ***
    thats very poor excuse
    the descent rates in no wind and in steady winds MUST match 100% ***or else*** u should ditch your 'model' completely
    u may not get simulation of control inputs or turns 100% right,,, nobody can,,, but not to match the descent rates is like writing a calculator program that when entered 2*2 gives 4.4. "yeah i know it must be 4 but my model is not perfect"

    "new version of my calculator will be better. 2*2 will be 4.2"


    I understand your feelings, though I disagree with the logic. If you would like to discuss this further we can do it in some other venue (at least not this thread).

    my logic is that its not ok to sell bullshit
    your prog fails an elementary bs check
    u disagree? its ok 4u to sell bs?!

  4. sjc

    ***So, how come I've timed ~10% difference (with a stopwatch) in flight_time with your Canopy Glide Simulator between 'No wind' and '13mph wind'?
    (steady 'no input'; 'half input'; full input' flight)


    The short answer is: the model is not perfect. The longer answer is, that there are multiple variables at play and the model must accommodate the steady state as well as the response to the inputs. This requires a compromise which results in parameters that produce overall behavior. By definition it is a mathematical approximation of the reality. As the model becomes better we'll see better results.

    thats very poor excuse
    the descent rates in no wind and in steady winds MUST match 100% ***or else*** u should ditch your 'model' completely
    u may not get simulation of control inputs or turns 100% right,,, nobody can,,, but not to match the descent rates is like writing a calculator program that when entered 2*2 gives 4.4. "yeah i know it must be 4 but my model is not perfect"

    "new version of my calculator will be better. 2*2 will be 4.2"

  5. we're talking about different things.. i didnt mean the quantitative difference between an object moving at 700mph and 20mph.. i meant qualitatative diff

    ok,,, one last try, more succinctly... two da vinci parachutes (essentially a round parachute with fully formed shape) r released from a balloon and from an airplane, from the same altitude simultaneously. which one will land first?

    my answer: the one dropped from the balloon
    this is the same answer, qualitatively, as with mythbusters bullet
    once u agree with that theres no reason not to agree that a round descends slightly slower through shear layers than still air


    your answer?

  6. >Not the same thing at all. And easily proved using regular Newtonian physics.

    how a bullet fired horizontally and a bullet dropped in the moving stream not the same thing? the result is the same.. it moves vertically slightly slower than bullet dropped in still medium

    >horizontal and vertical components of drag are no longer independent

    what do u mean independent? they r just projections of a vector, how they can be independent?

    >But format's thought experiment explicitly excluded shears.

    can u read b4 replying? when i finished with formats experiment, i introduced my own one, with shears.... reading comp probs?

    >Yep. Unfortunately it doesn't model the atmosphere.

    again can u read? i was talking about producing uniform stream in formats exp. it has nothing to do with the atmosphere, its a thought experiment!!

    i had F- in physics but even an idiot like me knows it better than "physics professor"

    hereby i demote u of your title and advise u to go to a middle school and start it from the ground up :ph34r:

  7. Quagmirian

    ***I vagely remember the episode of mythbusters where they proved that a bullet shot horizontally falls slower than just dropped

    Ahh, the problem here is that a canopy's airpseed stays the same regardless of windspeed. The bullet analogy is more suited to a skydiver exiting a moving aeroplane compared to a balloon or a helicopter. In this case, the airspeeds are different, so descent rate is affected.

    true
    i was only answering format's thought experiment

    otoh... by analogy with this experiment, even a round parachute (with zero forward drive) will change its decent rate when going through shear layers, and it will float down always slightly slower regardless of whether u go from faster layer to slower or vice versa

  8. >Since you can't make a 2' deep pool with steady current of a viscous fluid that has the same speed all the way to the bottom

    sure u can
    just move the entire pool (with still water in it)
    boom! for the object dropped from above in it its tye perfectly steady current of viscous fluid
    or just drop the object in nonmoving still pool with same horizontal speed
    its relativity
    e = mc2

    maybe u should take physics 101 mr "physics professor" :P

  9. format

    If I am to make a maple seed out of aluminium or other material and/or size to match density to water in proportion, as it does have proportion in air...

    and it emulates behavior in water exactly like real one in the air...

    You are positive that it will hit bottom of, say 2 feet deep pool at the same time as in another pool, same depth, with artificial steady water current (of any speed)?

    Give me a "yes" and I quit and thank you for your patience.



    the answer is "no"

    i vagely remember the episode of mythbusters where they proved that a bullet shot horizontally falls slower than just dropped

  19. Quote

    Don't be ashamed. you look like a sexy beast. A sexy flying machine.



    orange guy? yes.. i assume this is the111?

    but that blue guy? he's kinda weird.. see-through ws.. ass twice as wide as shouldres..transparent lower legs.. and right foot size what 20?! and and michelin hand in the cloud wtf!!!!

    :D

  23. normiss

    Looks to me that he stalled that bitch.



    u r right sir. now the question is he stalled that bitch because he had some technical problem (eg stalled engine) or because "Asoh fuck up". in either case looks like he tried to avoid hitting the seawall nose first by pulling the stick

    regardless of the reason that stall might have saved 300+ lives

  24. "Stabilized approaches have long been a safety concern for the aviation community," NTSB Chairman Deborah Hersman told CNN on Sunday, saying they represent a significant threat. "We see a lot of runway crashes."

    http://www.cnn.com/2013/07/07/us/plane-crash-main/index.html

    whats stabilized approach?