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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1answer
100 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 ...
3
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0answers
60 views
How does pitot tube shape affect indicated airspeed? [closed]
Air flow over wings and engine inlets greatly changes due to a number of factors, such as atmospheric conditions, speed, and the design of the surfaces. On some engines you can see mist behind the ...
0
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1answer
156 views
What is the bank angle that should be sustained to move in a uniform circular motion? [duplicate]
I want to deduce the rate of turn of targets that move in a uniform circular motion. The radius of the different circles are known in advance. I have searched for my question and found the following ...
4
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4answers
549 views
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 ...
0
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2answers
152 views
Do smaller wings mean faster flight? [closed]
I've known that military aircraft with small wings can fly very fast, while commercial aircraft with big wings cannot fly as fast. Why is this?
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1answer
244 views
What is the relation between IAS and TAS at a constant altitude?
I have noticed that when calculating True Air Speed for any given altitude, the faster the Indicated Air Speed, there seems to be a larger increase in TAS?
My thinking was that at a constant altitude ...
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0answers
23 views
What are typical Ki values for calculating indicated air speed?
IAS is defined as
IAS = CAS + Ki
where Ki is a correction factor typical of your aircraft. What is a typical value for Ki? I was not able to find any POHs online with Ki.
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3answers
131 views
What determines the maximum speeds for a particular aircraft?
Aircraft have three different maximum airspeeds:
VMO (maximum operating speed) - the maximum speed that the aircraft is allowed to reach during normal operations.
VNE (never exceed speed) - the speed ...
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0answers
60 views
How can I calculate different airspeeds given atmospheric data?
I want to calculate various airspeeds (TAS,CAS,IAS,..) given a certain altitude. With the given altitude I can figure out the pressure, density, speed of sound, temperature, and viscosity. However, I'...
7
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3answers
1k views
Why do aircraft need Mach number? [duplicate]
Why don't aircraft operates with IAS only?
Is there any other usage of Mach number except monitoring of shock waves formation?
How Mach number is calculated?
5
votes
1answer
130 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? ...
0
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2answers
185 views
What is the meaning of “static pressure”?
I don't really know what static pressure is. Does the ASI (Airspeed Indicator) use cockpit pressure as static pressure, to find the dynamic or differential pressure?
I just found this statement :
...
2
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2answers
426 views
What is the maximum angle F-16 can turn in x seconds flying at corner speed?
How can one calculate the maximum turning angle F-16 can turn in x second flying at corner speed. Is it changed with height or weight?
3
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2answers
106 views
How does the mechanical linkage of the airspeed indicator convert dynamic pressure to KIAS?
I understand the underlying principle of an airspeed indicator, ie. that it uses the Pitot-static system to measure the dynamic pressure as the difference between total pressure and static pressure.
...
1
vote
1answer
199 views
What's going on with sudden acceleration/deceleration in mid-air?
I was recently on a flight between LGB and PHX. I've been flying since I was 5, am now 31. After takeoff, as the plane approached cruising altitude, the plane slowed down. A lot. Then accelerated ...
8
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1answer
369 views
How an Engine thrust changes with airspeed? Why?
I'm interested in how the thrust of a turbofan engine is affected at higher airspeeds (TAS). I know (I believed) that engine thrust(at constant N1) was relatively constant like in the following graph (...
5
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3answers
363 views
What scale is the speed trend line on a PFD's ASI?
A primary flight display (PFD) in a glass cockpit has an airspeed indicator (ASI) that doesn't just display the speed, but also a vertical arrow or bar that shows the "speed trend" i.e. the ...
0
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2answers
302 views
Is there a speed needed to achieve flight?
Is there a minimum speed needed for flight (universally)? For example, if something was going 10 miles per hour, could it achieve flight? And by flight I don’t mean throwing a paper airplane, I’m ...
5
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1answer
109 views
How would a low-airspeed fixed-wing drone be designed to reduce effects from gusts and wind shear?
In a story I am working on, the characters need a fixed-wing drone that can rendezvous with a blimp, where by "rendezvous" I mean "come within a very short distance at low relative airspeed". The ...
4
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2answers
270 views
If maximum speed was a priority for modern military fighter jets and bombers, approximately how fast would they likely be?
Burt Rutan talks rather passionately about the lack of innovation in space flight, but also mentions how fighter jet (maximum) speed performance has stalled:
In fact,...
18
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6answers
6k views
Would a slower speed and lower altitude reduce fatal incidents?
If it became plausible to fly commercial aircraft much lower in the future (due to developments in technology and airway regulations permitting it), say at a standard height of 5,000ft, but with a ...
2
votes
2answers
513 views
How can the zero-lift drag coefficient (parasitic drag) be calculated?
Consider a 3-D wing made from an arbitrary airfoil, say a NACA0012 airfoil. The wing has a trapezoidal shape, with a fixed span, root chord, and tip chord. Also, assume that the wing loading is known ...
5
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2answers
781 views
Why does an airspeed indicator not simply read TAS?
If the airspeed indicator has inputs regarding air density (static port) and temperature. Why isn't Indicated airspeed from the indicator simply the same as True airspeed
3
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1answer
89 views
What is the rate of acceleration based on downward pitch?
In other words, I want to understand how gravity converts into thrust in respect to pitch. What is the general mathematical relationship? (For visuals, imagine a bird diving to gain speed.)
2
votes
1answer
142 views
What is the name of centre of mass speed of an aircraft?
I have a list of positions (X [NM], Y[NM], Z[NM]) of an aircraft. Every coordinate is given every 1 second.
I calculate the speed [knots] between two consecutive coordinates in the following way:
$...
4
votes
2answers
361 views
What is the relation between maximum airspeed and engine power?
I know that the drag force on an airplane scales as (velocity)^2 which implies that doubling the airspeed will produce a 4x increase in the drag force. So my question is:
Imagine we have an airplane ...
2
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1answer
563 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 ...
6
votes
2answers
559 views
Why does X-Plane 11 show the SR-71 at 200 knots but Mach 3 at 80,000 ft?
So I noticed on X-Plane 11, the SR-71 reaches Mach 3 at 80000 feet, but the equivalent airspeed is only around 200 knots. What explains this difference between the mach number readout and the EAS ...
4
votes
1answer
191 views
Is it possible for an airliner to cruise at engine full thrust?
What would happen if the pilot of a modern airliner like the boeing 747-800 or Airbus A380 left the throttle at full thrust at cruise altitude for an extended period of time e.g 4 hours if the ...
9
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2answers
238 views
What type of airspeed are wind speeds given in?
When you get wind speed from an ASOS/AWOS or from ATC, are those speeds in true airspeed? Are the instruments weighted for elevation?
Say you're on approach to 05R at MEX and you're given wind speed ...
3
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0answers
78 views
How does an ADIRU convert ram air pressure from the Pitot tube into Airspeed?
I know how the analog Airspeed Indicator shows the Airspeed from the ram air pressure from the pitot tube. But I'd like to know how an ADIRU converts the raw pressure data to Airspeed that is ...
13
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6answers
3k 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 ...
7
votes
6answers
479 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 ...
22
votes
7answers
2k views
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 ...
4
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0answers
405 views
What's the relationship between drag divergence Mach number and maximum operating limit Mach number?
The drag divergence Mach number, also known as the force divergence Mach number, is the Mach number where drag waves start to form. The drag divergence Mach number is typically between 5 to 10 ...
2
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1answer
347 views
How to calculate the best climb rate and glide rate?
Considering the lift equation
$$L = C_L \frac{1}{2}\rho v^2 s$$
Given $P$ is 1,000 ft, $\rho$ is 0.002308, and $V$ is the cruise speed of a Piper Archer or 126 knots, we get
$$L = (0.4) (0.002308) (...
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votes
2answers
12k views
How to calculate the real Ground Speed from True Air Speed?
In most of the formulas I've found online GS = TAS + Vw, i.e. true air speed plus wind.
However, on the simulator, GS changes drastically if I dive or climb which is obvious because I'm covering 0 ...
5
votes
3answers
974 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 ...
2
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1answer
972 views
How are IAS to CAS conversions calculated?
How do I calculate calibrated airspeed (CAS) from indicated airspeed (IAS)? For example, how is 600 knots indicated calculated to 595 knots calibrated?
9
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3answers
1k views
What prevents a Machmeter from being the standard airspeed indicator?
Airspeed is more accurate when displayed by a Machmeter than when displayed by an airspeed indicator. It isn't affected by ambient temperature / density changes. It is still affected by position error,...
27
votes
6answers
1k views
Why does Airbus not display the exact airspeed on the PFD?
On every other PFD (I know), the exact airspeed is displayed as big number on the PFD. To clarify what I mean, here are two pictures:
Source, added square, Boeing PFD
Source, added square, D10A EFIS
...
4
votes
1answer
863 views
What would be the stall speed of Solar Impulse?
In most of the tables, only the take off (22 mph) and cruise (43) speed of the Solar Impulse are listed. It is an experimental plane, slow, with very huge wing for solar batteries.
The take off speed ...
76
votes
12answers
27k 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 ...
3
votes
1answer
222 views
What's the speed callout by the PNF on airliners for?
On all Airliners, there is a speed callout by the PNF at some point during take-off, usually at 80 or 100 KIAS.
Whats the reason for those callouts? And why are some at 80 KIAS and some at 100 KIAS?
5
votes
2answers
1k 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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2answers
371 views
What was the first operational U.S. military jet fighter to fly at mach 2?
Was it the McDonnell Voodoo or the Lockheed F-104A?
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3answers
1k views
How does change in airspeed affect pitching moment?
In aircraft with conventional elevator control, if I increase the speed, the horizontal tail sees higher velocity and hence higher lift. Does it mean that increasing airspeed creates nose down ...
2
votes
2answers
641 views
What are typical airspeeds and lift coefficients for UAVs at different flight stages?
I've been trying (unsuccessfully) to figure out the relationship between airspeed of a fixed wing UAV at different flight stages. What I mean is, I would like to know the order of airspeeds from ...
1
vote
1answer
331 views
Is there a difference in aerodynamic efficiency between single engine and twin engine airplanes?
I've learned a lot of great information about aviation on this website. One insight I learned from a poster here is that, all else equal, for every doubling of engine power that you give an airplane, ...
2
votes
3answers
4k views
Why do we need to know both groundspeed and airspeed? [duplicate]
As far as I understood it correctly:
airspeed: is obtained by measuring the difference in airpressure (using Pitot tubes I guess?) around the aircraft and the airpressure caused by propulsion.
ground ...
