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.

Filter by
Sorted by
Tagged with
4 votes
0 answers
80 views
+50

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 ...
11 votes
3 answers
1k 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 ...
2 votes
1 answer
123 views

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 ...
2 votes
2 answers
129 views

Minimum sink speed and maximum endurance speed

For a given airplane, are the minimum sink speed and maximum endurance speed the same? Thankyou
2 votes
1 answer
3k views

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 ...
4 votes
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.
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 ...
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 ...
0 votes
1 answer
45 views

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 ...
8 votes
7 answers
924 views

How can a passenger determine airspeed without a handheld GPS?

This question is in the context of being a passenger on a commercial airliner, where you're in the cabin and the cockpit door is locked. In another question, someone posited that if an airliner had ...
1 vote
2 answers
587 views

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, ...
3 votes
1 answer
53 views

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 ...
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 ...
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 ...
3 votes
2 answers
325 views

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 ...
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 ...
11 votes
3 answers
3k views

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. ...
1 vote
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 ...
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....
86 votes
15 answers
45k views

What is the slowest fixed-wing airplane?

It's easy to find information about the fastest airplanes, in different categories (e.g. X-15, SR-71, the Concorde etc), but what is the slowest one? Which powered, manned airplane is capable of ...
0 votes
0 answers
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
2 votes
1 answer
175 views

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 ...
0 votes
1 answer
142 views

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 ?
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 ...
0 votes
0 answers
32 views

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 # ...
0 votes
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 ...
5 votes
0 answers
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 ...
2 votes
1 answer
2k views

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 ...
8 votes
4 answers
2k views

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 ...
0 votes
2 answers
5k 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, ...
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 ...
6 votes
3 answers
4k views

Why do pilots normally fly by CAS rather than TAS?

I think I know the answer to this question, but I want to confirm. Airline pilots normally fly a CAS/Mach profile, which means that above the CAS/Mach transition altitude they fly by Mach, and below ...
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 ...
18 votes
1 answer
8k views

The SR-71 flew at 2193 mph. Mathematically, how can this be Mach 3.3?

Virtually every time I read about the Lockheed SR-71 Blackbird (including other threads on this forum), I see that its speed record is listed as approximately $2193$ mph. The same blurb will ...
23 votes
2 answers
58k views

What is the reason for changing the speed reference (IAS or Mach number) with altitude?

Inspired by that question: How is the airspeed-Mach number transition handled in modern airliners? When pressure and density decrease IAS also decreases. When temperature and pressure/density ...
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 ...
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 ...
4 votes
1 answer
3k views

Best glide speed vs. best glide angle? Maximum glide range?

I have some open questions regarding best glide in a descent: I understood, that there is a best glide speed. This best glide airspeed occurs at the highest lift-to-drag ratio (L/D). This best glide ...
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 ...
4 votes
1 answer
354 views

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+...
11 votes
3 answers
5k views

Can a helicopter really fly with rotors going this slow?

I was watching this youtube video and I noticed that at 3:17 seconds they show a coast guard helicopter rescuing a man from a ship. Whats shocking about this is that the main rotor of the helicopter ...
6 votes
5 answers
9k views

Why does indicated airspeed change with altitude?

I know that if you fly at a low altitude and at a high altitude at the same TAS, your IAS will be lower at the high altitude than at the low altitude. Why is this though? Wouldn't the static vent ...
-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 ...
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 ...
-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.
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 ...
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 ...
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 ...
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 ...
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 ...

1
2 3 4 5 6