What is the difference between Airspeed and Groundspeed?

Question

In an airplane speed thingy, what is the difference between airspeed and groundspeed? Is airspeed w/ the wind? Is groundspeed w/o the wind? O_O or IS there such a thing as "groundspeed?" Please help. thanks :D

Answer 1

There are five basic types of airspeed: indicated (IAS), calibrated (CAS), true (TAS), ground speed (GS), and mach.



The most basic, airspeed given is the indicated airspeed. IAS essentially gives the speed that air is traveling over the wings to generate lift. IAS is generally not a very accurate indication of how fast the aircraft is actually traveling, but it does indicate whether or not the aircraft is flying. All things remaining constant, an aircraft will always stall at the same IAS given a constant configuration (CLmax AoA) at all altitudes.



Calibrated airspeed is IAS corrected for known instrument deviations. Usually CAS is very close to the actual IAS and varies by just a few knots.



True airspeed is the actual speed of an aircraft through a column of air. True airspeed is CAS corrected for density altitude (ie, corrected for air density, temperature, humidity, etc...)



Ground speed is simply the aircraft's speed over the ground, and it is derived by taking TAS +/- a tailwind or headwind, respectively. GS is used, among other things, to determine the time it will take to travel a certain distance. The GS of an aircraft is very comparable to the speedometer in a car, they both indicate speed over the ground.



And last, the mach number indicates how fast an aircraft is traveling through a column of air in reference to the local speed of sound (LSOS)--the formula is TAS/LSOS. It is important to note that the LSOS changes drastically with temperature, so LSOS is typically faster at lower altitudes and slower at higher altitudes (barring a non-standard condition like a temperature inversion). Mach has absolutely nothing to do with ground speed, so even though you might have a tailwind pushing your aircraft making the ground speed faster than the speed of sound, your mach number may indicate well below mach 1 because, remember, mach is only relevant to the speed of the aircraft through a column of air in reference to LSOS.



PS, Skipper, haha, I have never met a single pilot that actually still uses a slide rule anymore. And that's a good thing because I'd probably crash the plane trying to read that aggravatingly small print.



@Skipper, the T-34 is a good aircraft, they are just recently retiring the T-34 fleet from the Navy and replacing them with the T-6. I also think its funny that you reference Sportys, some guys live and die by that website :)

Answer 2

Airspeed is the speed at which air moves past the aircraft as it flies. Ground speed is the speed of the aircraft over the ground. If there's no wind, both speeds are the same. But in most cases there is some sort of wind blowing, and depending on the direction and speed of the wind, the airspeed may be very different from the ground speed.



For example, if the airplane is flying north with an airspeed of 100 mph, and there's a wind blowing south at 20 mph, the airplane's speed over the ground will be 100 - 20 = 80 mph.

Answer 3

Indicated airspeed (IAS) is studying taken straight from airspeed indicator. It's the number that the needle aspects to on the dial. This worth isn't corrected for variations in the density of the surroundings, set up error (brought on via the role of the pitot tube and static ports), or blunders precipitated by the instrument itself. Indicated airspeed drops as you climb, for the reason that because the density of the air decreases with altitude, fewer air molecules hit the pitot tube. This effect is most seen in high-performance plane that operate at excessive altitude. For example, at cruise altitude, the airspeed indicator on the Boeing 737-400 may just indicate about 280 knots when the airplane's specific velocity by means of the air is greater than 400 knots. Pilots use indicated airspeed to get the proper performance from their plane. Takeoff, climb, method, and touchdown speeds are all centered on IAS. Calibrated airspeed (CAS) is indicated airspeed corrected for set up error and instrument error. The difference between indicated airspeed and calibrated airspeed is in general greatest at low airspeeds, when the air waft around the static ports is turbulent. The position of the pitot tube and the set up of the airspeed indicator itself also make a contribution small errors to the airspeed indicator. Decreasing the flaps may also increase the change between IAS and CAS. To compensate for these errors, pilots consult with tables in the plane handbook to determine calibrated airspeed (CAS) below various stipulations of flight. Proper airspeed (TAS) is the genuine pace of an aircraft by way of the air. The airspeed indicator displays TAS only at sea stage underneath general stipulations, so that you have to calculate TAS centered on IAS, the present pressure altitude, and air temperature. By and large of thumb, you can estimate TAS with the aid of including 2 percentage to IAS for each and every 1,000 ft of altitude. Pilots use TAS in navigation calculations and when submitting flight plans.

Answer 4

Just a fun fact to demonstrate what's already been said. I've been in a J-3 Piper cub showing an airspeed of about 30 m.p.h. Because the headwind was so strong we were actually traveling backwards. Go figure...

Answer 5

'Speed Thingy"?



That doesn't even deserve a response. Good luck.