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#41
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Chad Speer wrote:
This is interesting. I hadn't considered breaking them up into headwind and crosswind components. I see the simplicity in that, but I'll have to run that through the brain a few times to see how it fits. I certainly can't dismiss it offhand! No crosswind calcs needed. No trigonometry needed. Just addition and subtraction. In your case, aircraft always follow a specified course. Headings don't matter. Crosswinds don't matter. The only thing that changes is their speed, and that's simply TAS +/- wind speed for a particular direction. So if you calculate at startup the head/tail wind (TAS-GS) for two aircraft flying basically North or South, and East or West, then you have enough rough information to extrapolate the speed of the trainee's airliner, as it turns to face different directions. It's not precise, but it's good enough to make things more realistic by at least having the speed change appropriately for each direction. Kev |
#42
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![]() "d&tm" wrote in message ... "Chad Speer" wrote in message oups.com... Terry - thanks for the reply, but heading is not known. Stefan - we need to be able to plug these known values into a formula and kick out a result. Assuming the original responder was on the right track, I still don't know what to do with his suggestion. Any ideas on that? I'm not lazy, this just went over my head a long time ago. :-) Chad, sorry misread the question. But I like a challenge so I had another go. Firstly I dont believe the equations given by the original poster are correct. if you apply the cosine rule to the wind triangle for 2 aircraft you get the following 2 equations. TAS1^2=WS^2+GS1^2-2WSGS1COS(180-ABS(WD-TR1) TAS2^2=WS^2+GS2^2-2WSGS2COS(180-ABS(WD-TR2) WHERE TAS1 AND TAS2 ARE TRUE AIRSPEEDS FOR AIRCRAFT 1 AND 2 WS = WIND SPEED WD =WIND DIRECTION IN DEGREES MAG TR1 AND TR2 ARE TRACKS MAGNETIC FOR AIRCRAFT 1 AND 2 GS1 AND GS2 ARE GROUND SPEEDS FOR AIRCRAFT 1 AND 2. (180-ABS(WD-TR) WILL GIVE YOU THE ACTUAL ANGLE BETWEEN WIND DIRECTION AND TRACK. Further to this post ,using the above 2 equations , with the following correction cos( abs( abs(wd -tr)-180)), the problem was solved graphically by solving the 2 quadratics , or 3 for a 3 aircraft case for wind speed, for each of the 360 degrees of possible wind direction. this gives you a parabola for each aircraft and the overlap of the parablolas gives you the required answer. For 2 aircraft there can be either 1 or 2 solutions. having a 3rd aircraft will give one unique solution.. This solution is available as an Excel spreadsheet if anybody is interested. terry |
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