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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What are the equation linking static air temperature with true airspeed & altitude?
If I want to calculate static air temperature (OAT), but I'm only given an altitude and a true airspeed. Is there such an equation that relates these principles together. I've had a look at wikipedia ...
15
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1answer
4k views
Why is a 737 Original speed-restricted below 10 kft with inoperative windscreen heating?
According to this page on the 737's operational limitations, the Original 737s (737-100/-200) are limited to 250 KIAS below 10 kilofeet if the windscreen-heating system is inoperative:
Anti-Ice &...
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4answers
994 views
Is any device installed on airplane to measure wind speed relative to the ground, and its direction?
A device or tool which can measure actual wind speed to the ground rather than to the airplane. Also a device which detect the wind direction to the plane. The device I meant is something like this ...
6
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2answers
2k views
Is it right to extend flaps only in the white arc?
If the cruise speed is >80kts on the downwind leg but I can only extend flaps in the white arc, am I right in saying I need to get to the white arc, even if I'm on - for example - 100kts?
For ...
4
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1answer
151 views
Why use Mach number for describing the speed of aircraft?
What does Mach speed mean for describing aircraft speed if the speed of sound changes with temperature?
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1answer
212 views
Why does the F16 HUD give you one number for your speed and the analogue gauge another?
Why does the F16 HUD give you one number for your speed and the analogue gauge another different number?
6
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4answers
1k views
How does speed affect lift?
I understand the lift coefficient shown above. But does lift increase with speed, and how?
I understand I can't apply this to the graph as it is a coefficient, but if I had an angle of attack of 10 ...
4
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2answers
197 views
What is a jet engine's fuel flow at constant IAS?
Here is my assumption:
In straight and level flight of a jet turbine engine:
One IAS = One drag = One thrust = One fuel flow
Therefore, the fuel flow will be approximately the same for a ...
3
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1answer
76 views
Airspeed Calibration alternate static source, what is this for?
I found a 'Airspeed Calibration Alternate Static Source' Figure in C172R POH.
There are three kinds of Figure,
1. Heater off, Vents and Windows Closed
2. Heater On, Vents Open and Windows Closed
3. ...
5
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0answers
243 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 ...
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3answers
453 views
What is the difference between TAS and GS? [duplicate]
I'm looking for an explanation of true airspeed and ground speed.
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2answers
192 views
Are there locations/altitudes with minimum speed requirements?
For example, a slower aircraft operating on the North Atlantic Track System would have an operational impact on surrounding/overtaking aircraft as well as potentially increasing ATC workload to ensure ...
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2answers
80 views
How can I calculate the speed gain from using multiple STC modifications together?
Looking at a parts manufacturer website, they list various STC'd modifications for Mooneys with estimated (cruise?) speed gains for each.
However, I've heard that those gains are not additive. For ...
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2answers
440 views
What is the fastest unpressurized aircraft?
What is the fastest unpressurized aircraft with oxygen masks that can carry people?
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1answer
94 views
How do I calculate TAS from IAS in this question?
How can I calculate the answer to this EASA PPL ECQB question?
An aircraft cruises at altitude 5000 ft on a heading of 180° with an
indicated airspeed of 100 kt. The wind vector is 180° with 30 ...
6
votes
2answers
995 views
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 ...
3
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1answer
147 views
Does the MU-2 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 ...
3
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1answer
255 views
How does an airspeed indicator look from the inside?
How does a typical GA airspeed indicator look from the inside and how does it work?
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1answer
154 views
What will be the performance penalties of increasing the wing area of a delta winged aircraft to obtain a lower approach speed?
Delta winged aircraft such as the Dassault Mirage III have an approach speed of 170 knots as specified by the manufacturer.
The Mirage F1 was designed to have a lower take off and landing speed than ...
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0answers
206 views
How to find TAS for given CAS, FL and OAT?
Here is another question for my PPL Exam. If anyone can illuminate me with explaining every step to achieve TAS with given parameters, it would be great.
Given:
Calibrated airspeed (CAS): 155 kt. ...
2
votes
1answer
555 views
How to calculate Equivalent Airspeed immediate 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 chain step.
IAS is clear. This is function of pressures. With Bernoulli equation, ...
7
votes
4answers
455 views
Does diving after a take-off help gaining altitude?
I have often read fictions about aircraft, where a pilot does an action that I cannot explain:
During a takeoff with an heavy aircraft (four motors for example), the pilot rolls to the end of the ...
6
votes
1answer
135 views
Airliner speed when descending through 10,000 feet
How do airliners get to 250 kts when descending through 10,000 feet as required by the FAA? Do you level off at 10,500 feet until speed is less than 250 and then descend further? Must pilots ask ATC ...
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3answers
264 views
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 ...
2
votes
1answer
144 views
How do changes in flight affect L/D max and the speed at which I must travel to maintain it?
I have an plane flying at L/D max and I want to maintain L/D max.
Firstly, if this plane burns through a portion of fuel and becomes lighter, how would I have to change the speed to maintain it?
My ...
0
votes
2answers
136 views
What’s the speed for lowest sink rate on a DA20?
In the DA20, the POH lists for glide speed (flaps up) only one speed giving the best glide angle / furthest distance (73 KIAS).
But what about, if I don’t need that much distance to glide (e.g. ...
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2answers
271 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 ...
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2answers
1k views
What is the effect of altitude on true airspeed?
I know that wind is taken into account when we compute the TAS(true airspeed) and GS(ground speed). However what is the relationship between the TAS and altitude?
For example: What is the true ...
2
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1answer
205 views
How is altitude correlated with true airspeed?
I am trying to understand the BADA 3.0 dataset (specifically I am looking at Performance Summary Tables):
E.g.
What is not obvious to me is why those tables mention only single TAS for specific FL.
...
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1answer
107 views
Is there an increased concern for stall safety in a 1G steep turn?
Most people know the standard, "At a 60 degree bank, an aircraft experiences 2G's" checkpoint for load-factor on an airplane.
I assume that this statement has an underlying, unspoken assumption that ...
13
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6answers
7k views
Why is indicated airspeed rather than ground speed used during the takeoff roll?
My instructor asked me this question during my lesson and I couldn't come up with any answers. He asked why do I need to look at the indicated airspeed rather than ground speed when in takeoff roll or ...
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2answers
95 views
Pitot tube pressure question
I have this question is the pressure measured in the entry of the pitot tube the same when the plane is flying headwind or turning a 360 degree turn while maintaining the same indicated airspeed?
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2answers
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Why is trim for take off affected to Vmc(Speed maintain control)?
I am studying in Vmc part, but I have hard time to understand that trim for take off is affected to Vmc. How and why does it make Vmc speed increase?
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2answers
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What is a jet (unit) shown in Windows 10 calculator? [closed]
From Windows 10's calculator:
What is a "jet" (physical unit)?
And why does it equal 480 knots or 888,88 km/h, if a jetliner's cruising speed is around 950 km/s? Or why does it equal 0.73 M, if a ...
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1answer
117 views
Temperature sensor are needed to compute True Airspeed for low speed aircrafts?
I know standard air data computer can produce true air speed with total air pressure, static air pressure, and total air temperature. But for a low speed aircraft <100 knots, do I need to install a ...
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1answer
251 views
Why were the space shuttle’s flight controls only certified for low airspeeds?
Somewhat ironically for a vehicle designed to reach orbital speed, the space shuttle’s flight control system was only certified for airspeeds up to 333 KIAS, and exceeding 470 KIAS (the maximum ...
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2answers
122 views
How should I answer this question about measuring airspeed using dynamic pressure?
I have come across a question in the PPL Principle of Flight material which I can't understand how to answer:
Give your opinion on the statement "Measuring dynamic pressure is the
way to ...
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2answers
410 views
What are the consequences of touching down at too low of a speed?
The consequences of a high speed touchdown / high vertical speed are very much obvious. However, what will the consequences be of a low speed touchdown? How severe are they (if any)?
6
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1answer
315 views
Why are the positions of an aircraft's angle-of-attack vanes dependent on airspeed?
According to this answer to an earlier question of mine, the positions of the angle-of-attack sensor vanes on the A330/A340 are dependent not only on AoA, but also on airspeed (and, according to @ymb1'...
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1answer
84 views
What is a simple way to explain why best range airspeed is below normal cruise airspeed? [closed]
Without using complex mathematics, please explain why best range airspeed is less than normal cruise airspeed.
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4answers
824 views
What is the official unit of airplane/aviation speed?
Some units I read/found are commonly used in aviation: mach, knot (nautical mile per hour), mile per hour (mph), kilometer per hour (km/h or kph).
"Official" meaning like the units used by the flight ...
12
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2answers
873 views
Why do aircraft have a crossover airspeed, and why does it increase at higher vertical load factors?
According to the NTSB accident report on the crash of USAir Flight 427, all commercial aircraft have a crossover speed (the speed at which the maximum rolling force from the aircraft’s ailerons and ...
5
votes
4answers
239 views
Do airline pilots use speed stability to cope with unreliable airspeed indications? If not, why not?
There have been a couple of airline accidents in which unreliable airspeed indications (or the fear thereof) have played a role:
Birgenair Flight 301 in 1996, where one of the pitot tubes was blocked,...
4
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2answers
1k 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
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2answers
308 views
What is an accurate expression to calculate IAS as a function of TAS? [duplicate]
Does anyone know a good source for an expression of IAS as a funtion of TAS? I was hoping to find an accurate IAS equation that is only dependent upon TAS, static pressure and static temperature.
6
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1answer
222 views
Why are airspeed gauges labeled above Vne?
Examples:
Cessna 150L Vne = 141 knots (162 MPH), gauge labeled to 170 knots. It looks like there's room to extend the scale to 180.
Cessna 152 Vne = 149 KIAS, gauge labeled to 170.
Cessna 172R Vne = ...
2
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7answers
2k views
How does maximum speed vary with altitude?
Question: How does a commercial jetliner's highest possible groundspeed vary with altitude (assuming wind=0) ?
My understanding is that drag decreases with altitude, therefore maxspeed increases with ...
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2answers
221 views
Why is the normal operating airspeed so much lower than the cruise speed in this table?
I need to work with the following table. I'm interested in vMO which I assume I can simply obtain from converting MMO to vMO through $M = v/ \sqrt{1.4 * 287 * T}$. (Is that correct?)
However, I ...
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1answer
572 views
Difference between Mach buffet and shock stall
What is the difference between Mach buffet and shock stall?
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2answers
800 views
How can I compute the minimum possible bank angle for a turn with a given radius?
I know that I can find an upper bound for the bank angle for a plane, if I know the maximum sustained load factor of that plane because the roll angle and the load factor $n_z$ in a turn are directly ...
