Questions tagged [airspeed]

The speed of an aircraft relative to the air. Among the common conventions for qualifying airspeed are: indicated airspeed ("IAS"), calibrated airspeed ("CAS"), true airspeed ("TAS"), equivalent airspeed ("EAS") and density airspeed.

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Why did the Solar Impulse flight take so long?

The Solar Impulse just made big news for flying from Japan to Hawaii on a solar-powered plane in five days. But five days seems really long. Let's do the math on that. The distance from Japan to ...
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Why do fighter jets land faster than Jumbo commercial aircraft?

From my own understanding, the bigger (and heavier) aircraft, the higher approach speed it needs to keep itself from stalling. According to this site, the approach speed of an A380 is 140 knots, and ...
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What is meant by “Control your descent with throttle when landing, not with pitch” [duplicate]

I have heard it said on several occassion that when you are landing you need to control your descent with your throttle, and not with your pitch. Two closely related questions that I think can be ...
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Why does speed lose out to capacity?

The Concorde had a maximum speed of 2.05 Mach, carrying about 96-128 passengers. The Airbus A380 can achieve a top speed of 0.95 Mach with more than 500 passengers on board. This means roughly 5 times ...
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What is the fastest recorded backward flying plane?

It is a well known fact that some planes like the Antonov An-2 can fly backwards since their stall speed is lower than the speed of the winds they can stably fly into. My question is what is the ...
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Is the Mach number shown by an Air Data Computer considered a “true” Mach number?

I am trying to find more information on "true" vs. "indicated" Mach number (not airspeed). I've found older fighter aircraft manuals online that have a conversion chart from one to the other, but the ...
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Why is the initial short-field climb below Vₓ in a Cessna 172?

Short-field takeoff procedure for a Cessna 172R is Wing Flaps – 10°. Brakes – APPLY. Throttle – FULL OPEN. Mixture – RICH … Brakes – RELEASE. Elevator Control – SLIGHTLY TAIL LOW. ...
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How long after takeoff for a Boeing 747-400 to reach cruise speed?

Assume it is fully loaded (pasengers and cargo) and optimal conditions, almost no wind, etc etc... How long after takeoff does the plane reaches cruise speed? If he goes in a straight like on the ...
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When a plane flies faster than the speed of sound, does the distance between plane and sound increase?

I had this discussion with my dad about a question he had asked. Basically he said: If a plane flies faster than the speed of sound, will he be able to overtake his own sound and hear itself? (let'...
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What is the actual air speed over and under a wing due to Bernoulli's Principle?

Bernoulli's Principle states that as a fluid speed increases, its pressure decreases, and vice versa. Air flowing over the wing of an aircraft flows faster than its neighboring air flowing under the ...
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1answer
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Why is the XB-70's Top speed only about 60mph higher than its cruise speed?

The maximum and cruise speeds listed for North American XB-70 Valkyrie are: Maximum speed: Mach 3.1 (2,056 mph, 3,309 km/h) Cruise speed: Mach 3.0 (2,000 mph, 3,200 km/h) Why is there such ...
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What is the difference between targeted airspeed and selected airspeed?

Are Targeted Airspeed and selected Airspeed the same thing? And can someone explain in what cases managed airspeed or pilot selected airspeed would be used, i.e. for different flight phases/...
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Would TCAS ever issue a “climb, climb!” RA that would stall a jet with a low airspeed?

As a for instance, let's say there are 2 jets going at low airspeeds (close to $V_S$) that get too close to eachother and a TCAS Resolution Advisory callout is announced. Would TCAS issue an RA to ...
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Does a plane have brakes to stop or slow down while flying?

Does a plane have brakes to stop or slow down while flying? For example, if the pilots see a large flock of birds at some distance in front of the airplane, and they want to reduce speed suddenly. ...
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Is there a surface of a commercial jet exposed to air flow at speed near Mach 1?

With commercial aircraft flying slightly above Mach 0.8, is there any surface exposed to speed of air significantly larger, e.g. near Mach 1? ignoring: The engine components, The boundary layer as ...
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Is it possible to have V1 greater then Vr?

According to wikipedia, decision speed ($V_1$) is computed taking into account the runway length (and other parameters). If an aircraft uses a long runway (one listed here), there may be enough runway ...
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Is there any equation to bind velocity, thrust and power?

I am designing a remote controlled airship. I will tune it so that the lift given by Archimedes' Principle will exactly balance the weight of all the structure. It will be propelled by brushless ...
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How does an energy variometer work?

In a comment to an answer regarding instrumentation complexity, an "energy variometer" was mentioned, labeled in knots. What does this dial actually show, and how does it work? The image accompanying ...
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3answers
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Why are planes slower at higher altitudes?

On many flight simulators, I have noticed that planes tends to get slower with increasing altitude. For example, I can reach 1100 knots just above the sea level in Google Earth flight simulator(F16), ...
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How is V_S0 calculated for anything less than maximum weight?

Is there a way to (safely) calculate the stall speed of an aircraft ($V_{S0}$) for anything below maximum weight? All the tables in the POH are valid for maximum weight only, and stall speed can drop ...
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Why is there a difference between GPS Speed and Indicator speed?

I just played with flight simulator and noticed that the GPS shows different speed from the speed indicator in the cockpit. Also, GPS speed is higher than the Indicator. Any Idea why?
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Don't all airspeeds change with weight?

Ok, so I'm a student pilot, and I'm going over the Vx, Vy, Vne, ... etc., and I see that "maneuvering speed" (the speed at which you can safely apply full flight controls) "changes with weight". ...
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Which maneuvering speeds are included in the TCDS?

I've been looking at the data found in various type certificate data sheets and found something that is a bit ambiguous. In reading a TCDS (like this one, for example) in the "airspeed limits" section ...
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What protection does Vno provide?

VNO, the airspeed where the green and yellow arcs meet on the airspeed indicator, is the "maximum structural cruising speed" (FAR 1.2). An airplane should only be flown above VNO in calm air. ...
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When can spoilers be used on airliners?

On airliners, are spoilers used in any part of flight other than landing?
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How does a Mach Meter determine the speed of sound at a given altitude?

By my understanding, the Mach Number at a given altitude is calculated by dividing IAS by the speed of sound at that altitude. So how is this speed of sound calculated to display the Mach Number on ...
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Why do some military aircraft use variable-sweep wings?

There are a couple of American military aircraft (the retired F-14 and the B-1 come to mind immediately), that have variable swept wings. I know that they keep the wings full out (roughly ...
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Are there limits to speeds at certain altitudes?

Are there speeds that cannot be exceeded at certain altitudes?
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How does exceeding the critical Mach number of an aircraft affect its operation?

If an aircraft exceeds its critical Mach number, does it affect the way the aircraft is handled? Are there any significant changes to performance or the safety of the aircraft when above this speed? ...
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Is IAS without instrument error the same as CAS?

I was reading a POH which stated something along the lines of NOTE Except as noted, all airspeeds quoted in this handbook are Indicated Airspeeds (IAS) in Knots and assume zero instrument ...
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What is the difference between planned true airspeed and actual true airspeed?

My electronic E6B does calculations for both planned and actual true airspeed (yielding different results). I was told the difference has to do with assumptions about temperature, but the manual doesn'...

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