What is the proper way to calculate Groundspeed?

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What is the proper way to calculate true groundspeed? I found some examples on the web, but they did not make sense as there were no altitude references. I thought the higher you went the more difference it made.So my question is, what is the formula one uses to figure this out.While you mathmeticians are at it... could you give me some fuel calculations too? Basically what does one usually set in % for taxiing, takeoff, climb, flight... etc.Thank you!JohnnyKTUS

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Groundspeed is the speed the aircraft is actually moving across the ground at... the ways to calculate...1) Look at your GPS that will tell you groundspeed.2) For VFR Navigation (with no GPS), you need maps and a flight computer.As an example, you have a town on a map and another town 15NM away in a striaght line. Take your time over Town #1, take your time over Town #2. Say it took 7 minutes to travel the 15NM. Your groundspeed would be roughly 128 knots. Knowing you are traveling 128 knots, you can calculate your time to destination.True Airspeed needs altitude reference as it involves density altitude. You'll need a flight computer to figure that one out to the exact number, but generally for every 1000 feet gain in altitude you can expect a 2% increase in TAS. (Roughly) So if at 2000 feet you're TAS is 100 kts, at 8000 you can expect roughly 112 knots. (6000 feet gain 2 knots per thousand giving the 12 knot gain in TAS)Not to sure what you mean for Fuel %... every aircraft burns different for taxi, climb etc.. If I remember the real C172 POH says to use 2 gallons for start/taxi/runup/climb. A Navajo will burn 240 pounds per hour in cruise, and an Aztec burns 180 pounds/hr in cruise.If you are talking power percentages... In the Navajo and Aztec we use full power takeoff, at 400-500 feet AGL, climb power is set, and in cruise, cruise power is set.. all will burn significantly different fuel figures depending on the aircraft.Hope that helps a little.Chris

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> I never use the GPS any more only opening it >to verify my calculations are close to what the GPS says. >All this added to your knowledge and realism in the sim for >less than \$20! Quite a bargain if you ask me. >Happy flying! >Since using real life GPS's since the early 90's, I'm a staunch advocate for them! I'd like to see "moving map" GPS's in every cockpit, unless the land is flat & the air is clear....Living in the Mt. West, such as I do; I'm seeing far too many aircraft crashes into elevated terrain, when dark or flying into un-planned IMC. The same goes for IFR approaches where the pilot looses his/her situational awareness, then proceeds to loose altitude while attempting to get back on track. Moving map GPS's provide INSTANT situational awareness & can save a pilot's ### as well as their passengers.Simming with pause buttons if needed, and figuring where you are, can be fun in a simulation. But I'll take real detailed map & terrain GPS's anyday over outdated technology of the past, which includes VOR's, NDB's, whiz wheels, and so on.L.Adamson

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>Living in the Mt. West, such as I do; I'm seeing far too >many aircraft crashes into elevated terrain, when dark or >flying into un-planned IMC. The same goes for IFR approaches >where the pilot looses his/her situational awareness, then >proceeds to loose altitude while attempting to get back on >track. Moving map GPS's provide INSTANT situational >awareness & can save a pilot's ### as well as their >passengers. I agree that GPS's are great, especially when flying near controlled airpspace.But most *standard* GPS', e.g. Garmin 530 do not have any terrain info.

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