# 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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### How do I find the minimum level flight speed at 0 and 10,000m? [closed]

I have to find the minimum level flight speeds at 0, and 10,000m. From my understanding the minimum speed would be near stalling point(?) I made a graph of the C_l and C_d corresponding to the angle ...
109 views

### is there a way to convert speed into g-force, or do you need acceleration too? [closed]

kind of a stupid question, just wondering.
2k views

### Is trimming for constant speed equal to trimming for constant angle of attack?

My understanding of trim: When you say you have trimmed an aircraft for a constant speed, say 100 mph, you are actually trimming the horizontal stabilizer so that there are no forces on stick (or tail ...
2k views

### Does airspeed affect the critical angle of attack on an airfoil?

I understand that the critical angle of attack is mostly affected by the shape of the airfoil. However does the airspeed of the airfoil or the density of the air affect the critical angle of attack? ...
330 views

### Why is airspeed different in climbs and descents although the AoA doesn't change?

Here are the background facts: This excercise has the objective to familiarise the student with the slow flight characteristics. The steps are: 1)Establish straight and level, 90% RPM, 15 units AoA, ...
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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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### 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), ...
4k views

### 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. ...
689 views

### Do aircraft using only spoilerons for roll control, with no conventional ailerons, have a crossover airspeed?

Airplanes generally have a crossover airspeed (a minimum airspeed below which directional control of the airplane cannot be maintained in the event of a rudder hardover). This is because, as airspeed ...
138 views

### 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 ...
271 views

### 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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### Does a sudden drop of the velocity of the headwind affect the airspeed by lowering it?

I had a discussion about air speeds with one of my instructors recently. He is claiming that there is a sudden drop in the wind velocity as you get closer to the ground (which is absolutely true, due ...
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### What is the true top speed of the SR-71?

By "true" top speed I mean the absolute fastest horizontal airspeed the aircraft can achieve if damage to the engines is disregarded (similar to how the MiG-25 apparently can reach mach 3.2 but may ...
5k views

### What is the difference between a pitot tube and a pitot-static tube?

What is the difference between a Pitot tube and a Pitot-static tube? If an aircraft fitted with Pitot tube and static holes on the fuselage, is it necessary to consider the static pressure ...
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### Which air stream pressure / speed is measured by the pitot?

The pitot tube is used to measure the air pressure later converted into air speed. However air pressure varies according to several elements, including the location related to the wing: (Source: av8n....
108 views

### Relation between weight of the aircraft and mach number [closed]

Is there any formula that relates weight of the aircraft with mach number?
131 views

### 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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### 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?
162 views

### 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?
160 views

### 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 ...
81 views

### 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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### Does the F-16 have a speed limiter?

In an aircraft like F-16, how do the pilot prevent going faster than Vne (velocity, not exceed)? From the block 50 manual it seems to indicate Vne is 800KIAS/2.05M. I believe even the earliest F-16s ...
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### What is the regular stall speed of an F-16 flying in a straight-and-level path?

I want to know what is the minimum speed that an F-16 can fly at without stalling. I have searched the web, but found no exact information answering my question. Most of them say that it depends on ...
112 views

### What is the required accuracy of an airspeed indicator?

What FAA document specifies the accuracy to which an airspeed indicator must be calibrated to?
264 views

### 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 ...
409 views

### 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 ...
644 views

### 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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### How do you convert true airspeed to indicated airspeed?

Is this something found in the POH? I know there is a IAS and CAS chart.
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### How to calculate Equivalent Airspeed immediately from Calibrated Airspeed?

I want to calculate each step like IAS -> CAS -> EAS -> TAS as a chain. Each chain step should depend on the previous step. IAS is clear. This is a function of pressures. With the Bernoulli equation, ...
292 views

### 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 ...
94 views

### 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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### 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 ...
65 views

### Maximum climb angle [duplicate]

I've got this graph of vertical climb rate vs airspeed, and ive been asked to find the maximum climb angle from the graph, but I'm not really sure what part of the curve shows this. I can do the math ...
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### Why does an increase of airspeed result in a decrease of angle of attack?

In Chapter 02: Aerodynamics of Flight of Helicopter Flying Handbook, on page 10, it says: Induced flow velocity is increased, resulting in a decrease in AOA. I don't understand how airspeed can ...
184 views

### 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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### Why does the speed of commercial airliners fluctuate, sometimes as high as 1,060 km/h or as low as 800 km/h?

I've noticed that (long-haul) airliners sometimes travel at as high as 1000 km/h (I believe I've even seen 1040 km/h), but usually they fly closer to 800 km/h, for most of the trip. This seems odd ...
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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 ...
729 views

### What is the highest indicated airspeed ever achieved in a traditional aircraft?

It is fairly well known that the SR-71 holds the record for highest speed for a traditional aircraft (not a rocket/able to land and takeoff under its own power). However since the SR-71 flies much ...
2k views

### 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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### Is it possible to modify an AV-8B Harrier II to a supersonic aircraft by applying some modification?

Is it possible to convert McDonnell Douglas/BAe Systems AV-8B Harrier II Plus into an effective and usable supersonic aircraft? May be, by changing the engine or applying some modifications on the ...
171 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 ...
6k views

### Is it possible to accurately measure airspeed without pitot tube?

This is a follow-up to my previous question: How does this IMU work and how to convert its output into meaningful information? for which many people asserted that I need a pitot tube and a static ...
9k views

### What is the commercial passenger aircraft top speed record?

Aircraft manufacturers claim that commercial passenger aircrafts cruise at the speed of 400-500 knots. But, is the top speed of a commercial passenger aircraft recorded (while in air)? If so, what is ...
2k views

### 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 ...
458 views

### 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, ...
260 views

### How does supercruise thrust compare with static thrust ASL?

As I understand it, turbojet thrust decreases both with altitude due to rarefied air reducing massflow, and airspeed due to a smaller speed increase between intake and exhaust relative to the airframe....