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Why doesn't "Ground Speed" factor in AoA??

4,287 Formula350  3.0 years ago

I mean my understanding until just now, after actually looking it up, was that the whole point behind the term "Ground" speed, was to provide your speed "in reference to the ground."

Therefore, while Head and Tail winds are important, it seems that AoA is equally, if not the most important, element.
Because if you have a Thrust to Weight ratio >1 and are literally rocketing skyward at 90degrees, your TAS or IAS are what to look at... Since you're traveling straight up and would have a "GS" reading of theoretically zero. (assuming no wind present, and keeping a true and locked 90deg angle)

That being said, if my original understanding WAS correct and I've only after looking it up, misunderstood something... Then it would mean that SimplePlanes' GS calculations are bugged and need fixing.
In my testing, TAS == GS, which made me wonder why GS was even included.

[Note: You can toggle between the three speeds, GS, IAS, or TAS by clicking on your speed readout on the built-in UI HUD -- I don't know for Mobile, touch the location maybe. The system you have set will remain the same, whether it's Knots, KMH, or MPH, but the reading will simply change based on the selection. I think TAS is the default selection.]

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    @Formula350
    "ground speed vs air speed"
    KN AVIATION - this explains it well
    NASA - reliable source you can use as a reference

    +1 3.0 years ago
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    4,287 Formula350

    @BlinIndustry That's pretty much exactly what made me go o_0, was switching over to GS and noticing it didn't matter if I was going up, down, or horizontal, its speed didn't vary any compared to TAS. heh


    @hpgbproductions So it's sort of like Doppler Shift, in that like the sound of something passing by having its pitch change (depending on whether it's coming or going), GS is more our "perception" of the speed we're traveling at?
    (not to say that Doppler Shift is meerly our perception, as it has a much deeper basis in physics, such as Redshift.)
    .
    Doppler Shift happened to be what my brain drew a parallel to. That is... if I understood correctly? heh

    3.0 years ago
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    Relative to the ground is a bit misleading, more accurately it's relative to any fixed point and the velocity vector includes the vertical component.
    GS is only different from TAS when there is wind, because TAS is relative to wind. IAS is also relative to wind.
    .
    You can try it:
    GS = sqrt( pow(rate(Latitude),2) + pow(rate(Altitude),2) + pow(rate(Longitude),2) )
    Horizontal GS = sqrt( pow(rate(Latitude),2) + pow(rate(Longitude),2) ) = GS * abs(cos(PitchAngle))

    +3 3.0 years ago
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    8,420 BlinIndustry

    Interesting,
    However I think GS is just a "True Speed" of a aircraft speed that it's going.
    Since I used GS before, I remember I tried to do a loop on a plane, the GS doesn't drop to zero at all, which means the GS doesn't work like you think.

    Just like I said, GS is just a actual speed that the aircraft going.
    For example, when I fly a plane goes mach1.5 of GS and do a loop, GS will only drop because of the drag when doing a loop; but if there's no drag, my plane will still goes GS mach1.5 when doing a loop.
    So it just a actual speed that you are going without counting other things.

    3.0 years ago