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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Please describe ram pressure in simple terms

Please someone describe the following sentence in simple words: The Airspeed Indicator is calibrated for 'standard' sea level density, so it will only read TAS if the density of the air through which ...
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Atmospheric Turbulence Magnitudes

In an aircraft say B737, what will be the effects on altitude and indicated airspeed if the turbulence magnitude between 1.5 and 2?
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3 votes
2 answers
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How do test pilots verify TAS?

This question is about what methods/technology test pilots have at their disposal to verify airspeed indicator calibration during flight-phase testing. A paper published in 2001 by David Rogers ...
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What is the green arrow on the 777's airspeed tape? Does it exist on other types as well?

Image source: fsnews.eu I found this green arrow on the primary flight display (PFD) of a 777. What does it show? I'm assuming it's for showing acceleration and deceleration but I am not too sure. Is ...
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3 votes
1 answer
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Calculating airspeed by flying in a U shape: Horseshoe Heading Technique

I saw some equation in a log recently and I believe it went something as follows: $v_1$ : flying North, $\ \ v_2$ : flying West, $\ \ v_3$ : flying South. $$ \text{TAS} = \frac 1 2 \sqrt{v_1^2+v_2^2+...
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Strange airspeed indicator in the Douglas X-3 Stiletto

The cockpit of the Douglas X-3 Stiletto has a rather weird looking airspeed indicator. (The leftmost instrument in the top row.) Two concentric circular scales, the outer one goes from 0 to 20, the ...
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Why airflow travels faster on upper wings?

I have been looking for solutions and come up with two popular explanations: Conservation of mass / Continuity For a positive-cambered wing, the streamlines would be compressed/converged at the ...
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3 votes
3 answers
239 views

Power calculation of propeller

This is probably a very simple question, but I have been really struggling and need your help. I have simulated a propeller with these parameters on Ansys: Thrust: 2000 N Angular Velocity: 314 rad/s ...
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6 votes
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Do pitot tubes account for reduced pressure at altitude?

Do pitot tubes account for reduced pressure at altitude? Does indicated airspeed reduce with altitude? If so, how much? Is it different for small planes vs big commercial airliners?
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How are IAS/CAS and TAS used in flight?

Could you please explain to me one moment in relation to IAS and TAS. In all books I read I see that the IAS is highlighted as a reference for stall, take-off, landing and other performance items. So, ...
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How can an ultralight be slowed down for landing in a tailwind?

When flying an ultra light and I have a tail wind, and, with the engine at idle how do I slow down to land ?
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7 votes
1 answer
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What is the difference between Vs and Vs1g?

As the name suggests, what is the difference between Vs1g and Vs? If both of them are referring to the stall condition, why they aren't the same? Which one is usually greater and why? Why do we need a ...
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4 votes
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What's the penalty for exceeding 250 kts below 10,000 ft MSL without authorization?

What if any enforcement actions by the FAA are likely for exceeding the 250 KIAS limitation below 10,000 ft MSL?
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4 votes
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Ground Speed vs True Airspeed from Departure Point to Destination - time interval

Looking at navigation theory right now and I'm stuck in the understanding of TAS and GS. How does GS determine the time interval it takes for an aircraft to fly from the DP to the DEST, if TAS ...
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2 votes
1 answer
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How can I calculate 'Max aircraft Load Factor' and 'Max aircraft Speed' when flaps are fully extended on a civil aircraft? [closed]

I am trying to calculate the critical loading conditions for Flaps (in order use them inside my Finite Element Analysis to, determine if the Flaps will be able to bear these critical loads) during the ...
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2 votes
1 answer
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How can PreciseFlight speedbrakes double the drag while being so small?

Look at this photo of some PreciseFlight© speed brakes: On the website it is claimed that these little red plates can double drag and descent rates. I cannot believe that. Can this be true, and if ...
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-3 votes
1 answer
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If the altitude of the aircraft is given by the pitot tube, in icing condition with heat on, how is real altitude /speed interpretation done? [duplicate]

If the altitude of the aircraft is given by the pitot tube, in icing condition with pitot heat on how is real altitude /speed interpretation done? Because the air density and temperature is not ...
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What is propeller pitch speed?

I was using Ecalc to calculate some flight parameters and then I came across this term called "propeller pitch speed". Can anyone explain me what this means?
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2 answers
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What are the relations between Angle of attack and Calibrated Airspeed?

I would like to estimate Angle of Attack using trigonometric relations i.e AoA = arctan (w/u) airspeed components (i.e u, v, w). When I am considering body 'x' velocity ('u' component), is it ...
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Do aircraft travel faster at higher altitudes?

I'm aware of the difference between TAS and IAS, and how IAS gets lower in reference to TAS as you climb and the air gets thinner. What I'm trying to figure out is whether or not an aircraft's IAS ...
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Does the airspeed indicator measure speed inaccurately at different angles of attack?

A point of confusion for me has been this: Does the pitot tube measure the airspeed of the plane in the direction of its flight path, or does it measure the speed of the air parallel to the pitot tube ...
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4 votes
1 answer
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When is Vmo/Mmo applicable?

I have read that for most planes Vmo (maximum operating speed) is the limitation below 25000ft and Mmo (maximum operating Mach number) is the limitation above 25000ft. Is it correct to say this and, ...
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3 votes
2 answers
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Does anyone know why IAS and Mach are inconsistent in Boeing FCOM?

The following figure is extracted from Boeing FCOM that I downloaded from the Internet: I noticed that Mach and KIAS values are inconsistent. An example is in red box. Let me show what I found: $$ \...
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6 votes
2 answers
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What’s the difference between an AIRSPEED LOW warning and a STALL warning?

Just an enthusiast here; pardon the dumb question. Im a little confused between the difference of a stall and airspeed low. “An aircraft Stall Warning System is that system which provides the pilot ...
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is there a way to convert speed into g-force, or do you need acceleration too? [closed]

kind of a stupid question, just wondering.
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6 answers
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How does it feel like to be outside a flying airplane?

Riding a motorcycle on a freeway at over 200 kph you surely feel the rush of air around you. A typical commercial jet airliner travels at approximately 3-5 times that speed at cruise altitude. ...
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Why is this equation for TAS only valid for subsonic flow?

I came across the equation for calculating True airspeed (TAS) on Wikipedia: $$ \text{TAS} = a_0 \sqrt{\frac{5 T}{T_0} \left[ \left( \frac{q_c}{P} + 1 \right)^{2 / 7} - 1 \right]} $$ But this equation ...
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Can a slow small plane, flying at a few meters above the ground, drop to the ground if the headwind abruptly stops? [duplicate]

Why do I ask this question? Because Wilbur Wright sent a letter to Georges Spratt (an aviation enthusiast he personally knew) saying that his plane, Flyer II, once in flight, accelerated easily to 45 ...
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-6 votes
1 answer
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Relation between weight of the aircraft and mach number [closed]

Is there any formula that relates weight of the aircraft with mach number?
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3 votes
0 answers
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How did the Wright brothers measure the maximum airspeed of their 1904 plane?

The Wright brothers used during their 1904 trials (105 in total, according with their claims) a Richard anemometer mounted on Flyer II (there are numerous pictures on the net with such a device). The ...
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5 votes
3 answers
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The slowest to fastest ratio plane [closed]

What fixed wing, and motor, plane or jet, has the largest range between its minimum and its maximum airspeed by which it can safely fly for prolonged periods?
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1 answer
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So fast, it melts the ice off?

Approximately, how fast would an aircraft have to travel through freezing air to melt the ice off the wing, propellers, or rotor blades?
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9 votes
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What equations and constants did they use to build the E6B flight computer?

E6B Flight computer: During my practice test, I tried to use the wikipedia provided equations to calculate Density Altitude and ended up with different results than the E6B. In this case, it looks ...
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0 votes
2 answers
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What airspeed is required at sea level to create the same aerodynamic pressure as cruise altitude?

I would like to know what speed would be required, at sea level, to exert the same aerodynamic pressure as experienced at cruise altitude. For example, if an airliner were traveling at 500kn at 35,000'...
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7 votes
1 answer
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Why this P-51 limitations placard for diving?

I noticed that this placard has different diving speeds related to altitud. My guess is that those values are a safety speed to prevent going into regions close to Mach 1. I know that the speed of ...
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What is the required accuracy of an airspeed indicator?

What FAA document specifies the accuracy to which an airspeed indicator must be calibrated to?
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7 votes
3 answers
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Could airliners fetch data like AoA and speed from an INS?

If I understood what an inertial navigation system (INS) is, it should be able to calculate speed and orientation of the aircraft. If this is possible, why do airliners solely rely on sensors to ...
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1 vote
6 answers
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Why does TAS increase as altitude increases and why does my C-152 POH seem to contradict this?

I remember learning and memorizing that TAS increases as altitude increases, however I don't understand why. Especially since my C-152's PoH seems to indicate the opposite in the cruise performance ...
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How is airspeed measured on supersonic aircraft? [duplicate]

Behind the shock wave air is subsonic, would that not cause an issue with the pitot tubes or any other sensor?
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What's the relationship between AOA and airspeed?

We know that any aircraft will stall at its stall speed (for a specific weight, CG position, etc.) but also, that the same airplane will always stall at the same angle of attack. I´ve read that IAS is ...
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1 answer
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Fighter Jets speed [duplicate]

How does an aircraft measures (or calculates) its speed while in air? Which equipment or sensors are used for measurement of speed? Does it takes Earth as a reference frame for its speed measurement ...
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What would cause a non-zero indicated airspeed reading on the ground?

What kind of failure would cause an indicated airspeed of say 200 knots on the ground (stationary)?
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Why are pitot-static measurements preferred over other velocimetry techniques?

I believe hot wire anemometers (HWA, frequently used in wind tunnels to measure flow velocity) or other sensitive techniques could be used to determine the airspeed. Are there specific reasons for why ...
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2 votes
2 answers
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Why do I get an overspeed warning at 250kts below 10,000ft in Microsoft Flight Simulator?

I'm flying the Cessna CJ4. I get overspeed warnings at 250kts when below 10,000ft, and the speed indicator has red lines at 300kts. Are these warnings triggered because it'll damage the plane to go ...
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2 votes
2 answers
386 views

How does altitude affect the TAS and thrust of an electric fan powered aircraft?

I'm confused about the relation between IAS, TAS, thrust, and shaft power, for an electric application. Yes, higher air is thinner, and thrust goes down due to higher airspeed. What I've researched ...
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12 votes
3 answers
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Is it possible for a plane to accelerate easily from 30 to 45 mph in flight while it struggles to reach 30 mph (the engine runs at constant power)?

In two letters sent to Dr. G. A. Spratt (an aviation enthusiast), Wilbur Wright reported the progress he and his brother had made, up to September 10, 1904, regarding Flyer II, a plane powered by a 16-...
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Why angle of attack is always shown against the relative wind parallel to horizon?

I have a question about Stall, which I have difficulty to understand. According to the theory, stall happens when : 1- Speed is slow then a certain limit. 2- Angle of attack is greater than a ...
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0 votes
1 answer
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Is Ducted fan or Propeller better to maximize forward speed of RC aircraft with a given power?

I'm designing an RC aircraft of which the final goal is a crazy top speed. I'll be 3D printing and sanding / finishing the air frame surfaces to reduce drag. In order to achieve maximum top speed, ...
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3 votes
1 answer
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Is propeller wake turbulence quantifiable based on operating conditions?

I know the propeller does work on the air and thus the flow behind a propeller is higher than the airspeed. However, what is the quality of this flow? If I were doing a heat transfer analysis of an ...
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2 votes
4 answers
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Why are true and indicated airspeed different?

So, I understand that True air speed is the motion of aircraft relative to air around it. And, indicated airspeed is speed arising due to dynamic pressure. Considering a true airspeed of 100 knots, ...
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