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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Comparing a Flight In Turbulent Conditions At Va And Vb

First, let's cover definitions for both airspeeds: Turbulence penetration airspeed (Vb) is the design speed for maximum gust intensity (i.e. the intersection between the 66 fps gust line and the ...
Darjan's user avatar
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Do departure procedure speed restrictions override airspace speed restrictions?

This is a speed restriction found on the BNGOS 3 RNAV Departure Procedure out of KOPF: SPEED: ACCELERATE TO 250 KT, IF UNABLE, ADVISE ATC Opa Locka airport is Class D and is also below the Miami ...
Lnafziger's user avatar
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2 answers
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Minimum sink speed and maximum endurance speed

For a given airplane, are the minimum sink speed and maximum endurance speed the same? Thankyou
Terry's user avatar
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1 answer
998 views

Why is calibrated airspeed (CAS) greater than indicated airspeed (IAS) at lower airspeeds?

As can be seen in the correction chart, the difference between the IAS and CAS is greater at lower indicated airspeeds, however when the IAS increases, the difference is minimal.
Alex Gallegos's user avatar
0 votes
2 answers
317 views

Is this flight GPS data intentionally manipulated?

Some flat Earth guy is trying to convince me that flight data is manipulated with and that planes travel faster in the Southern Hemisphere. Now this is obviously not true, in the video speeds of over ...
Mrh's user avatar
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Thrust needed to overcome parasite drag that increases with speed

Can anyone explain this passage from page 11-5 of the PHAK: “ For example, if an aircraft in a steady flight condition at 100 knots is then accelerated to 200 knots, the parasite drag becomes four ...
Terry's user avatar
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3 votes
1 answer
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Why does aircraft weight influence position (installation) error in pitot-static systems?

I am a private pilot from Argentina studying to become a commercial pilot. In one of the books I was given to study, published by the Chilean air force, the there's a claim (in Spanish, page 36) that ...
Nahuel Prieto's user avatar
1 vote
3 answers
324 views

What is the mathematical relationship between mass and speed for constant thrust in level fight?

Imagine that we have a wing with constant thrust in level flight. Then imagine that we add mass to that wing. In order to maintain level flight, I would expect that the angle of attack would need to ...
Monty Wild's user avatar
0 votes
2 answers
161 views

Why do I keep getting different results to an aircraft's turn radius when I plug variables into different calculators and solve on my own?

I'm trying to solve for an aircraft's turn radius at mach 3.17 (2432 mph) and a bank angle of 19.8; however, after using various online calculators and personally solving the equation, I keep getting ...
Sam Jones's user avatar
2 votes
2 answers
596 views

Why does Vx increase with altitude and Vy decrease?

As an airplane climbs, the best angle of climb airspeed (Vx) increases and the best rate of climb airspeed (Vy) decreases. I can't figure it out, why does it happen? I Hope someone explains it to me I ...
Aasena's user avatar
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Why was the Me 262's top speed at 6km?

The P-80 had its top speed at sea level, but the Me 262 achieved its top speed at 6km altitude. What were the reasons for this? Was it that the engine was designed for such an altitude to deal with ...
Vinicius Quintela's user avatar
0 votes
3 answers
246 views

Does AOA become 0 after the aircraft flies in a particular attitude for sometime as the relative airflow has changed and how does it affect Stall AOA?

As AOA is the angle between relative airflow and Chord Line. Then after you increase the angle of attack and fly at that angle of attack for some amount of time and the relative airflow changes ...
Nish's user avatar
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2 answers
258 views

Determine Vx and Vy from other climbing rate datas

I am developing a small program, working with Microsoft Flight Simulator 2020. For now, I can show my takeoff graph which display the altitude on the y axis and the distance in x axis. I would like to ...
Thibaultblf's user avatar
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65 views

Sudden Drop in Speed at 1h53 [duplicate]

can someone explain why the speed dropped so sharply and suddenly before going back up at 1h53 here: https://fr.flightaware.com/live/flight/MSR799
Sammy's user avatar
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1 answer
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Actual non-axial airflow (sideslip) for a propeller driven aircraft

I am making a propeller model for a two-engine propeller driven aircraft (like a Dornier 228). I have expanded my model to include the non-axial airflow as well. $$ $$ By non axial airflow, I mean ...
Neelabh Jyoti Saharia's user avatar
2 votes
3 answers
263 views

Does CG change airspeed in a descent or glide?

If the CG of an airplane moves forward, would it fly a faster or slower airspeed in a descent? Usually during a descent or landing, you'd use pitch to change airspeed and power to control descent rate....
thunderstormies's user avatar
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Why the ADS-B out doesn't broadcast the True air speed in its ES message?

The ASTERIX (version 2.1) items of ADS-B GS cat 21 contain True air speed but when we check the Asterix data that we recieved by GS we did not find the True air speed value, why ?
Uniform's user avatar
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Is it possible to calculate Calibrated Airspeed from True Airspeed, Temp, and Pressure Altitude? [duplicate]

Looking at a digital E6B, there is a function for calculating CAS that I am trying to recreate and program myself. Inputs: Pressure Altitude Temp in Celcius True Airspeed Outputs: CAS Mach # ...
Bellarose143's user avatar
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1 answer
389 views

How to Calculate Required True Airspeed to maintain desired ground speed?

Working on programming my own E6B and am stuck trying to calculate the following problem from Sporty's E6B: Given wind info and desired speed/course, what airspeed/heading should I have in order to ...
Bellarose143's user avatar
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441 views

Why do all trend vectors in the G1000 on airplanes indicate the status 6 seconds later? Why 6? Why not 5 or 10?

Why do all trend vectors in the G1000 on airplanes indicate the status 6 seconds later? Why 6? Why not 5 or 10? The fact that the trend vector shows after 6 seconds allows us to turn 3 degrees per ...
pilot162's user avatar
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1 answer
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How can TAS be calculated from indicated temperature and Mach number? [duplicate]

Situation I am working on programming my own E6B while I learn more about aviation, but I have run into some confusion. Two pairs of the equations are very similar except for using true or indicated ...
Bellarose143's user avatar
4 votes
4 answers
1k views

Why does an aircraft require less power when it is flying slower than the most efficient speed?

While I understand the derivation of Power required, I fail to understand why minimum power required corresponds to a velocity that is lower than velocity corresponding to minimum thrust required. My ...
Akshay Kashyap Panda's user avatar
0 votes
2 answers
227 views

Why isnt the structure of the aircraft affected by high true air speeds or high ground speeds?

Let's suppose that in Cruise flight I exceed the VNE in TAS or in ground speed, why isn't the structure of the aircraft affected by the high speeds? I am sorry for my english, I am not a native ...
Andres's user avatar
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4 votes
3 answers
789 views

Why does elevator trim hold a given airspeed? [duplicate]

I'm trying to understand a principle described in the book Stick and Rudder by Wolfgang Langewiesche between angle of attack and airspeed in relation to the elevator trim. He states that as angle of ...
RattMuscle's user avatar
1 vote
1 answer
387 views

how to calculate wind speed and direction using flight data, at some latitude and longitude? [duplicate]

I have a data file which has the aircraft state details with latitude and longitude recorded for certain radius. Now, I'm trying to calculate wind direction and wind speed. Example: At lat=41 and long ...
Siva's user avatar
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7 votes
1 answer
913 views

Mathematically calculate Mach number using CAS and PA WITHOUT flight computer

I am just wondering how to calculate the Mach number from CAS and Pressure Altitude WITHOUT the use of a flight calculator. E.g Given FL300 (30000ft) and 325kt CAS find and Mach number. I have always ...
Steven Shen's user avatar
-1 votes
2 answers
279 views

Why use indicated airspeed instead of dynamic pressure [closed]

It uses the difference between total pressure and static pressure, provided by the system, to either mechanically or electronically measure dynamic pressure. The dynamic pressure includes terms for ...
Abdullah is not an Amalekite's user avatar
2 votes
1 answer
245 views

Is my airspeed calculation code correct?

Not sure if I should ask here, on Drones SE, or on Code Review SE. Is my Python code for calculating airspeed given ground speed, ground direction, wind speed, and direction from which the wind is ...
kj7rrv's user avatar
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-1 votes
1 answer
138 views

Speed change in IFR flight in class C or D airspace

Can I change speed while flying IFR in class C or D airspace without having a clearance from ATC? I tried to find it in some documents on EASA website but I did not find anything.
Filip Adam's user avatar
2 votes
0 answers
171 views

Should the approach speed and wind be changed below 700ft on an A320?

The FCOM says: When managed, the speed target is computed by the FMGS and may be modified by the flight crew through the MCDU. At 700 ft RA, the current speed target value is memorized by the ...
user67133's user avatar
1 vote
0 answers
120 views

Does the reduced aerodynamic damping at higher altitudes affect the Vno (maneuvering speed) of an airplane?

Since reduced aerodynamic damping at higher altitudes reduces the needed control input for maneuvers, is this just about the required force to move the controls or also about the speed of the ...
Erik Stens's user avatar
1 vote
1 answer
291 views

Why does true airspeed decrease with altitude?

I was having a discussion with a friend who's going for a record speed over distance attempt. We were discussing which altitude will have the fastest TAS, and I suggested it would be the highest ...
Kenn Sebesta's user avatar
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2 votes
0 answers
281 views

Air density factor when calculating Airspeed

I am making my own attitude indicator / AHRS, like a Garmin G5. I am using two pressure sensors to measure altitude & airspeed via static /pitot lines. Now I know the formula for calculating ...
DMP52's user avatar
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0 votes
1 answer
133 views

Does optimum IAS for climb vary with altitude?

I was in an argument about aerodynamics and we eventually derived an equation as follows. So I'm going by this equation: $$RoC = \frac{\eta_p P-VD}{W}$$ Where $\eta$ represents propeller efficiency. ...
Tom Vu's user avatar
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3 votes
2 answers
905 views

How to determine the maximum forward airspeed of a plane in an unaccelerated flight?

What is the equation needed to determine the maximum forward airspeed of a propeller driven plane in an unaccelerated level flight? I need an example with units of measurements. The engine is rated at ...
Justintimeforfun's user avatar
3 votes
3 answers
397 views

Changing the missile's flight speed

I am interested in the range of velocity changes of missiles. Planes have a minimum speed set equal to the landing speed, helicopters also have a set speed - this is zero, but what about missiles? ...
user66348's user avatar
2 votes
0 answers
39 views

What is the speed of anti-ice bleed airflow in helicopter turboshaft engines?

If we consider the most modern turboshaft engines, what will the approximate speed for the bleed airflow when it's routed from the latter stages of the engine and supplied to the areas that require ...
Arthur C's user avatar
-8 votes
2 answers
186 views

What about measuring airspeed from control surface forces on the framework?

I watch a lot of these videos that people make about air disasters. One factor that seems (or hopefully seemed) to crop up is where pilots get hopelessly confused about airspeed, particularly (it ...
mike rodent's user avatar
3 votes
1 answer
158 views

Significance of $\frac{C_L^{3/2}}{C_D}$

I am aware that this value of lift coeff. over drag coeff. occurs when the zero lift drag is 3X the drag due to lift, and that this will correspond to a specific airspeed. What is the significance of ...
Caleb G's user avatar
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0 votes
2 answers
562 views

Confused about best range speed and Carson speed

I have read that best lift /drag ratio gives maximum range which makes perfect sense to me. I have also read Carson speed gives the best fuel consumption. which doesn’t make sense because this would ...
Ronald's user avatar
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1 vote
1 answer
530 views

Does Indicated Stall speed increase with altitude (Coffin Corner)?

It is my understanding that Indicated Stall speed is mostly constant with altitude, the one that increases is True Stall Speed. Given that PFD show speed as IAS, how come the yellow speed range ...
Max the head's user avatar
8 votes
3 answers
2k views

What is the general mathematical relationship between increasing an airplane's weight and the needed thrust to fly?

I understand that increasing an aircraft's weight without changing any other properties means that its takeoff, stall and cruising speeds all increase since you need to generate additional lift. So ...
J-bob's user avatar
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3 votes
2 answers
553 views

How is a "turning polar" constructed?

To start with something familiar: here's a flight polar. As we learned, the best glide speed is found by starting at the 0,0 point, and drawing a line tangent to the sink rate line. The intersection ...
Xpector's user avatar
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4 votes
1 answer
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How is CAS ans GS affected by instant wind changes at different altitudes

Okay, a theoretical example here which I hope will help me understand the physics better. Conditions: Altitude: 50 ft (over sea) GS: 300 knts CAS: 300 ktns Wind: 0 If I now get a 10 knts head wind (...
Jesper.Lindberg's user avatar
2 votes
1 answer
1k views

How to compute the airspeed change based on the Altitude change

The plot shows that: when I fly with fixed MACH, the true air speed decreases when the altitude increase; when I fly with fixed CAS, the true airspeed increases when altitude increase. So how could I ...
VvV's user avatar
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2 votes
1 answer
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Airspeed change in wind shear

The instrument questions I’m studying say that a decreasing tailwind will increase airspeed. I can’t wrap my head around why this would be the case.
rbsc's user avatar
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1 answer
320 views

TAS from POH or e6b

I always calculated my TAS at any cruise altitude by Using my planned cruise (pressure) altitude, temperature Plug desired CAS, PA, temperature into e6b and get TAS But I've also seen people get TAS ...
Jonathan's user avatar
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0 votes
6 answers
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Please describe ram pressure in simple terms [duplicate]

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 ...
Kqt's user avatar
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2 votes
2 answers
365 views

Modern method to verify speed of a homebuilt aircraft

Summary: In 2001, airspeed of homebuilt aircraft was calculated by flying in a ⊔-shape and using trigonometry to subtract wind effects. Now that we have portable computers, is there a more modern ...
Zaz's user avatar
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2 votes
1 answer
698 views

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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