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  • #31
    Originally posted by 3WE View Post
    Yes.

    I went ahead and made a second reply- flaming you for making me realize one thing...and to allow you to follow the process.

    The process:

    1. 3BS discovers graph that one could argue 'contains a moderately linear phase'...take that Gabriel, I am right and moderate flame!

    2. 3BS considers Gabby's comment that "AOA is a slightly vague term and that slight negative or 0 AOA's can result in positive lift...doubling negative numbers...seemed problematic to my 1:1 analogy...(Sarcastic, extreme flame for that nitpicky thing that it doesn't go through zero-zero...pedant...

    3. Well, since 1 and 2 have elapsed, 3BS has SINCE paused and looked at the Wiki AOA-Lift graph...the slope is nowhere near 1:1, more like 2:1.5...

    Argh...now what...

    3BS is a mechanistic thinker...to hell with your mathematical equations....tell me why in aggie English!

    If I have long board on a 2-degree slope and am rolling a wheel barrow up it, I get dang near almost twice the "lift" if I raise the board to a 2-degree slope. (minor trig adjustments ignored).

    Mechanistically, it seems to me that (with lower AOA's of course) if I double the AOA, I ought to roughly double the lift....

    I look at the example and instead of a 1:1 slope, it's more of a 2:1.5 slope...

    Ok, I'll go read your stuff- but scared it does not have a big fat clear summary statement to explain a 2:1.5 relationship...
    The problem why you fail to understand that you are wrong is that you are right, almost.

    a) Take a wing and fly it at an angle where it will make zero lift.
    b) Increase the angle (keeping the speed) until you produce lift = weight (i.e. 1G).
    c) Double that angle and you doubled the lift and the Gs.

    But, for example, a) is -2.5 deg, b) is 2.5 deg (and increase of 5 deg from a) and c) is 7.5 deg (another 5 deg from b, or total 10 deg from a).
    But obviously 7.5 is not 2*2.5.

    Now, if you measure AoA taking zero as AoA as the point of zero lift, then a) is zero, b) is 5 and c) is 10. Exactly as you expected.

    That's what I said, what you say is true if you put your zero AoA reference at the point of zero lift.

    And it doesn't matter if the ratio is 1:1 or 1:100.
    If it is 1:100, for 1 you have 100, and for 2 you have 200. It still hold that when you double one you doubled the other.
    But, you need the straight lie to cross the x and y axes in the origin, otherwise you have a linear function but NOT a proportional function.

    Again, it is the difference between y=mx and y=mx+b. An don't tell me that that is an engineers thing not an aggie one. My daughter is studying exactly that now in 7th grade and my other daughter is still studying that in 9th grade. And I bet that you studied that in the Advance Manuring class in the Aggie School.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
    --- Defend what you say with arguments, not by imposing your credentials ---

    Comment


    • #32
      Originally posted by 3WE View Post
      You said AOA of 0 was something of a judgement call as to exactly how to define it...
      Let me be less polite and say that it is totally arbitrary and that you can set it wherever you want.

      OK, I DEFINE 0 AOA as the AOA of zero lift...even then...my 2-degree vs 4-degree AOA does not give me 2X (times some sin, cosine, tangent slight correction figure of 0.98312) of lift...
      Then it works perfectly right. You are doing exactly what I said in my first post that you quoted and replied to thrice.

      Here it goes again, just in case:
      Only if your reference 0 deg AoA line is the zero lift AoA.

      --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
      --- Defend what you say with arguments, not by imposing your credentials ---

      Comment


      • #33
        Originally posted by Gabriel View Post
        No. I am being as straight as you are (oh my gosh, this can be totally misleading since I don't know how straight you are )
        ...
        6) Perform the plamface maneuver.

        Get it?
        No...I'm not that much of a dumbass, even though I am a dumbass...

        I understand what you said in the truncated quote above...but you are not addressing WHY there is an other than 1:1 relationship of angle and lift.

        The non-zero intercept is just a math game.

        If you read the two other replies (before you have had a chance to reply), I kick scream and yell that there must be an explainable, natural 'law of fiziks or something' to explain why it's not 1:1...even if I declared AOA of 0 is the AOA of zero lift...
        Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

        Comment


        • #34
          Ok, we are posting on top of each other...

          I will pause and do a safety check...currently, I do not believe that moving the line to 0-0 will cause it to yield ~2X lift for 2 degree vs. 4 degree AOA...

          Y = mx + b is not a foreign concept (other than it being Evan cryptic acronyms for slope and intercept)...
          Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

          Comment


          • #35
            Originally posted by 3WE View Post
            Oh shit and lol...I send a ban-worthy flurry of personal attacks and expletives in your general direction...pedant!
            @!#%@%#!!@#%@%@!#@$^!#@!$#^!#@%@#%!%!#%!%$@^%@!#$

            Everyone please PM Brian to tell him I laid multiple ban-worthy, expletive laden attacks on Gabriel, his family and his pets...

            Here's the deal...I DID figure it out on the second reply to Gabriel.

            When I move the damn line to zero zero...and double a small, lift-producing AOA, I get about double the lift...

            I KNEW IT WAS SORT OF DAMN NEAR A 1:1 RELATIONSHIP!!!!!!!!!!!!!!!! (Told you I think conceptually!)

            I do wanna say that the AOA to produce 1.8 G is not all that super impressive (since any number of maneuvers can produce 1.8 g)...maybe it ain't normal airliner operations...but I THINK 60 degree banks are considered well within an airliner's structural abilities.

            Yeah...sure, I'll face palm myself...I sort of got it all along, until Mr. Mathematics had to correct me on an arithmetic quirk.
            Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

            Comment


            • #36
              Originally posted by 3WE View Post
              PS: Article by "Daddy Rich", former head of Obscure Aviation Typists, ATL crew's top unofficial mentor...
              Not surprisingly, the point of the article seems to be to once again, for at least the eleven thousandth time, show what a guru Ol' Dick is...

              Comment


              • #37
                And a bonus track... you will love this:

                Since you were talking about the actual value of the slope of the CL vs AoA quasi-straight line, and wondering why it is not 1:1. I don't know why would you expect it to be 1:1, there is no reason for that, especially since the CL is dimensionless and the degrees that we use to measure are totally arbitrary, just a circle split in 360 pizza slices. God knows why some old primitive mathematician decided to split the circle in 360 slices, and not 200, or 100, or 10, or 12 or 60 that were more used numbers back then.

                In theory (and it is a relatively simple theory called thin airfoil, purely mathematical, where you assume very little other than the chord is much bigger than the thickness, the flow is non-viscous, and the flow will separate at the trailing edge), the slope of CL vs AoA is 2*Pi. Yes, that's tight, Pi like the ratio of the circumference to the diameter. 3.1516....
                And not only that, but in practice it is very very close to 2*Pi.

                I know, you will say "Come on, an airfoil 1 Deg above the point of zero lift will not make a CL of 2*3.14=more than 6!!! Just look at the chart, 10 deg above the zero lift point you have a CL of only about 1.1".
                And you would be right (although I doubt that you would have the presence of mind to say that, because that is an engineering thing rather than an aggie one)

                That's because I forgot to mention that the theory says that the CL will increase 2*Pi per RADIAN of increase in AoA. Not per degree.

                Now, how much is 10 degrees in radians? It is 0.175 radians. Multiply by 2*Pi and you get 1.1. Surprise!!!

                --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                --- Defend what you say with arguments, not by imposing your credentials ---

                Comment


                • #38
                  Everyone please PM Brian to tell him I laid multiple ban-worthy, expletive laden attacks on Gabriel, his family and his pets...
                  Don’t you bloody dare !!! If the slagging off was badly translated from German I might consider it but otherwise I’m keeping well out of this one !
                  If it 'ain't broken........ Don't try to mend it !

                  Comment


                  • #39
                    Co-incidentally I just received the February Aerospace America magazine that contains an article on microgravity experiments using a 727 aircraft (G-Force 1).
                    The article contains the following flight information:
                    After reaching a flight altitude of 24,000 ft the pilot increases the plane’s ascent angle to about 45 degrees to 32.000 ft. The aircraft eases over to the top of the parabola and rapidly descends, 20 degrees nose down, creating microgravity for 20 to 30 seconds.

                    The prior aircraft used for these type flights was a converted KC-135 fuel tanker dubbed “the vomit comet”.


                    The aircraft had several modifications, made to gain FAA approval, including a modified hydraulic system to prevent dangerous cavitation, or bubbles, from forming.

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