OK I am no flyer of the real world...always wanted but..whatever.
But this is really interesting..Rhythmosaur rightly mentioned that in a 200Kt headwind and 200 Kt a/speed, grund speed is zero..but are we saying here that real aircrafts DONT have goundspeed indicators?
I mean do pilots and navigators still use equipment to manually calculate groundspeed?! Pretty absurd and weird that would be...
I mean what with technology being where it is today..
Intersting thought...Concorde came in '69, what did they do then to calculate groundspeed at Mach 2!
Or another..do higher speeds like beyond mach 1/2 eliminate the headwind factor? what would be a speed where IAS and GS are the same?
Please excuse any noticable dumbness above..I am just a FS pilot!!
Flyrcoyle?
As far as I know - please anyone correct me when I'm telling crap - GPS devices and flight systems that work with it in airliners - work with the help of satellites. The Global Positioning System features a mass of satellites falling around this weird planet, and the device does contact them, that is it checks, which one it could reach and at what position. It needs to find at least 3 satellites (my real GPS needed) to be able to calculate the position.
In it's principles, it works the same like the ancient method of star navigation. The only difference is that not the position of some fix stars is compared and calculated, but position of those satellites. This works so amazingly accurate that you can trace down your positions to the centimeter (or inch). With a moving aircraft, positions are constantly calculated and compared, and from the differnce you can accurately define your groundspeed with no loss due to winds and other influences.
I guess, SpectroPro can even explain it more accurate for he is a flight teacher, so if he happens to not watch this thread, I recommend to contact him.
To Left Flyer: Yes, you do still use the manual methods to calculate groundspeed when flying above Mach 1. The main reason is simple, the jetstream. It often displays very high wind speeds that become very significant. Another reason is the higher altitudes (to attain Mach 1+) used by the concorde actually result in an airspeed that is significantly lower than Mach 1+ would be at lower attitudes.
To Rhythmosaur, you have a very good understanding of the way the GPS works, and I really can't explain off hand why you are experiencing the huge differences in GS that you seem to be. The only thing that comes to mind is that for years, the satellites actually transmitted a degraded signal in order to prevent opposing military factions from using that data to increase weapons accuracy against the U.S.. Perhaps, some of that crept into the programming of FS.
Yes, I heard about it from the seargeant who sold me his (civil!) GPS. He said, the civil once are not as accurate as the military ones for exactly the reason you mentioned. But the differences in two default FS systems (GPS and NavLog) are so high, and that was what confused me. I would have bet, both parts of this FS interiour systems use the same data for their calculation, so they must come to the same results. However, you can have a GS of 600kt indicated and NavLog tells about 700 to 800kt. That does not seem reasonable to me. Making a review for the Concorde and telling, the best groundspeed in ISA would be about 1100kt at FL 510, I'm sure there will be people in favour of the NavLog and telling (or at least thinking), that Dinosaur guy is telling crap and is unable to provide somewhat reliable data. Well, I think you know how people are...
But meanwhile, I now took up Insured Disaster's suggestion to use the GPS announcement for reference for obviously most of the simmers look it up there instead of the NavLog.
Everyone one is dead on with what they are saying. Another way to calculate ground speed is the trusty "E6-B" flight computer. Actually, it doesnt really look like a computer. Its a sort of circular slide ruler. You rotate a bezel of sorts to various positions and read off the numbers. By rotating the bezel to the proper position, you can adjust for alitude, and temperature. The flight computer has also come out for dedicated electronic computers (they look a lot like large calculators, though some are incredbly thin, so thin in fact, you can put them in 3 ring binders) , and addons for PDA's as well. Of course, as the original doesn't need batteries. . .
If you can, Left Flyer, go to a General Aviation airport or check with a General Aviation pilot and see one of the flight computers. They are fairly hard to describe them and should best be viewed. You can even buy one, as they are 100% compatible with all FS versions you might use today. In fact, while using my E6-B, I have never experienced a system crash. I would give it an "FS addon mark of approval."
By the way, while you are at an airport, see if some pilots have old or expired charts. Using charts and maps to navigate adds a new dimension in realism into FS. Many GA planes lack the color GPS systems and pilots usually fly with maps (GA pilots that is, Commercial pilots of the airlines don't fly with all the maps a small plane GA pilot might).
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