Questions tagged [v-speeds]

Questions on the critical speeds of an aircraft guiding elements such as rotation, climb, and maneuvering.

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7
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2answers
1k views

What does it mean to move a single flight control to its full deflection?

It is the speed below which you can move a single flight control one time, to its full deflection, for one axis of airplane rotation only This is part of the explanation of maneuvering speed. What ...
4
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2answers
436 views

What is the most fuel efficient climb speed for a C172 SP?

Assuming ISA, sea level, no wind, max gross weight, what speed would be most fuel efficient per 1,000 ft of climb? Alternatively, if that converges to the most fuel efficient cruise speed, when there'...
4
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2answers
124 views

Are there any aircraft where minimum-V1 is limited by Vmcg?

V1, unlike all the other Vspeeds, is not rigidly determined by the laws of physics, the aircraft’s specific abilities, and the conditions of the particular takeoff being attempted,1 but is, rather, ...
6
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1answer
114 views

Where does the factor 1.3 for Vapp come from?

The approach speed Vapp is usually given as 1.3 * Vs0, or 1.3 times the stall speed in landing configuration. Why 1.3? What created a consensus of 1.3 * Vs0 as the generally accepted textbook ...
3
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1answer
120 views

Are there reference speeds like V1, Vr or V2 for a touch and go procedure?

Are there any reference speeds like V1, Vr and V2 on a touch and go procedure? During takeoff, these are used to mark certain states of the takeoff, including the speed at which the aircraft starts ...
3
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2answers
186 views

Do modern aircraft automatically manage the deceleration to Vref?

Typically in most aircraft, the pilot manually reduces the speed gradually until reaching the landing zone/flare zone. Modern aircraft have FMC. Does the FMC automatically manage the speed gradually ...
2
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3answers
139 views

How are V speeds spoken?

How are V speeds spoken? --Research for my novel. Is it the V and the number or letter notation or is there something more to it? The Wikipedia Page on V Speeds does not delve into the subject ...
5
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1answer
219 views

Why not separate out the two definitions of V-1 into two separate Vspeeds?

V1, officially the takeoff decision speed, has, somewhat infamously, two separate definitions: It is defined as the minimum speed at which, if one engine fails, the pilots can press to liftoff and ...
0
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2answers
788 views

What is the difference between Vno and Va [duplicate]

What is the difference between the maximum structural cruising speed (Vno) and the manuevering speed (Va)? Can you also please explain how these speeds are calculated? I do understand that Va is set ...
5
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2answers
677 views

Why would one want to slow to V2 following an engine failure during takeoff?

Reading about the crash of American Airlines Flight 191, the proximate cause of the final loss of control was the pilots' reduction of the aircraft's airspeed to V2, in compliance with the published ...
0
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1answer
1k views

What's the difference of Vs from Vs0 or Vs1?

Vs: Stall speed or minimum steady flight speed for which the aircraft is still controllable Vs0: Stall speed or minimum flight speed in landing configuration. Vs1: Stall speed or minimum ...
1
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1answer
141 views

Why isn't Vy equal to Vmd?

$V_{md}$ is the speed where the rate of sink is the lowest. So if you add full power, it should be the speed with greatest rate of climb, namely $V_y$. But we also know $V_{md}<V_{bg}$ according ...
2
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4answers
771 views

Why is best angle/rate of climb indicated in airspeed?

I understand the difference between best angle of climb $V_{x}$ and best rate of climb $V_{y}$. When I take off I would aim to maintain one speed or another depending on what I want. But I don't ...
0
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1answer
449 views

Is there an aircraft that can go supersonic at sea level without using afterburner?

Is there an aircraft that can go supersonic at sea level without using afterburner? Quick look through the "supercruise" capable aircraft might be helpful in narrowing down the possibilities, though I ...
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3answers
1k views

Definition of “Rotation Speed” vs “Lift Off Speed” vs “Fly Off Speed”

Is rotation speed and lift-off speed ever used interchangeably? (AMENDED Question) Is lift off speed and fly off speed the same? (See supplemental info below) I thought I clearly understood the ...
1
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3answers
2k views

For what is VMCL the minimum control speed?

I would like to ask which of these options is correct: VMCL is the minimum control speed for: A) approach in go-around configuration B) approach in landing configuration C) go-around in ...
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3answers
480 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 ...
0
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1answer
277 views

What is the best glide speed for the DC-3 with 2 engines out?

What is the best glide speed for the DC-3 with 2 engines out? I realize we may consider best speed for ground distance traveled or best for duration - and that weight can be a factor. I can't find ...
-2
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1answer
516 views

What is the stalling speed of a Cessna 172SP at an altitude of 2000 feet?

What is the stalling speed of the Cessna 172SP if the temperature is +11 degrees Celsius, the power is off, the CG is at the forward limit, the flaps are at 0 degrees and the altitude is 2000 feet?
7
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2answers
383 views

Does MMO (limiting Mach number) assume any maneuvering limits?

This answer to a question about emergency descents notes: [Y]ou can accelerate descents by banking the aircraft into a turn. This allows you to increase angle of attack, thus increasing drag to ...
3
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2answers
473 views

Why is V1 based only on using brakes?

V1 is the speed that an aircraft may abort a takeoff so long as the airspeed is below it, or is committed to flight if it is over that speed. V1 calculations are based only on the brakes (not sure ...
1
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1answer
146 views

Is it a common airline practice to base T/O speeds on the actual T/O weight when an assumed temp thrust is used?

Let's say the current outside air temp is 15 C and you have decided to use 50 C as the today's assumed temperature for your takeoff. In this case, use of the T/O weight the assumed temp thrust ...
11
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2answers
10k views

How can V1 and VR (rotate) speeds be calculated?

I want to learn about how can the V1 and VR (rotate) speeds be calculated for take off. And which factors are affecting this calculation? Basically it may depends on the aircraft weight, runway ...
2
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1answer
150 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: $...
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2answers
891 views

Why should a Piper Seneca not take off after an engine failure below 100MPH?

In the Seneca (PA34-200) AFM, in the ENGINE FAILURE DURING TAKEOFF section, it is noted that if engine failures occurs during takeoff ground roll and 100 MPH has not been attained, the pilot must ...
4
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1answer
172 views

Is it possible to determine a rotation speed (Vr) using other known V-Speeds?

Is it possible to come up with a good estimate of rotation speed using other known V-Speeds? For example: if I know a plane has a Vs @ 55kt. and a ...
3
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2answers
1k views

What makes V1 one or two knots less than Vr on this performance table?

(B738 AFM, 0-2000 feet elevation, up to 27°C) Example of V1 and Vr differences. The table shows that the V1 speeds are invariably one or two knots lower than their matching Vr speeds. Given that V1 ...
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1answer
497 views

Is reducing V1 a viable option for pilots when the ASDA is shorter than the ASDR?

Let's say you were planning to ferry some passengers and cargo in a jet but after some calculations found out the ASDR (Accelerate-Stop Distance Required) was greater than ASDA (Accelerate-Stop ...
15
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2answers
2k views

Why is the takeoff decision point based only on speed and not time or distance?

The go/no go decision on takeoff for airliners is calculated as a V1 speed. The question is, why is there no time or distance for V1 calculated. In other words, if we don't reach V1 in X seconds or by ...
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2answers
1k views

Is there something like a table of aircraft required runway lengths?

I'm looking for a chart showing the minimum length a runway can be for various aircraft to land and take off. Does something like this exist?
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2answers
302 views

How should these translated takeoff and climb settings be interpreted?

I am having difficulties understanding this transcript. It is originally not in English, so I was wondering if anyone could help me to make sense of this and also help me with the correct wording in ...
14
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1answer
3k views

What is “Bird Strike Speed”?

I read through the reference speeds of the Hawker 850XP and I stumbled upon the "Bird Strike Speed". It is specified as "280 KIAS up to 8000 ft". What does that speed mean?
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2answers
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What is “50 ft obstacle climbing speed”?

Vy and Vx make sense to me. They are used for fastest height gain at a given time and biggest angle of climb. But what is the purpose of that speed (it's from DA20 POH)? It's only 3 kts faster than Vx....
11
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3answers
2k views

Why is ditching speed higher than stalling speed?

I was looking for a checklist for the Cessna 182 and I stumbled upon this one. When I looked at the speed-table, I found an interesting entry. It says "Ditching" with a speed of 65 KIAS: Everything I ...
3
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1answer
3k views

Why does V1 increase with weight? [duplicate]

(B738 AFM, 0-2000 feet elevation, up to 27°C) Example of V1 increasing with weight. This valid question came up the other day here in chat. The heavier the aircraft, the harder it is to stop. So ...
8
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1answer
747 views

Why is the V1-speed callout automated in modern commercial aircraft while VR is not?

In some modern aircraft such as the Airbus A380 or Boeing B787, the callout of the V1 speed is automated through a synthetic voice, based on the V-speeds entered into the flight management system. ...
5
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4answers
4k views

When does the overspeed alarm goes off in a plane?

I want to know when does the overspeed goes off in aircraft. How exactly is overspeed limit decided? Is it fixed for all the situations, or does it keeps changing? In a game that I play, (Infinite ...
1
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1answer
162 views

Why does the FAA SPL require different endorsements depending on cruise speed?

Part 61 section §61.327 requires that sport pilots require separate endorsements for aircraft with a VH below 87 KCAS and aircraft above 87 KCAS. What is the reason for two separate endorsements and ...
5
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2answers
5k views

What's the difference between Rotation speed vs takeoff speed?

My aviation teacher told us to memorize some speed values among other things before our flight training: $V_R$ = 40 kt $V_S$ = 39 kt According to wikipedia: Vr: The speed at which the ...
3
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2answers
1k views

Is V(L/D)max equivalent to best glide speed regardless of weight, engine, height, etc.?

I've read Carson's paper on V(L/D)max, and while theoretically interesting, it does not seem to me to be useful in actually finding the V(L/D)max of an arbitrary aircraft, as it assumes knowledge of ...
16
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1answer
401 views

Why is flutter a function of true, not indicated, airspeed?

I am learning about gliders in preparation for an exam. It says in the textbook I am reading that for a glider, you use indicated airspeed for most relevant speeds (stall speed $V_s$, best glide speed ...
7
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3answers
22k views

What are the landing stall speeds of a Cessna 172?

I understood from Why is stall speed listed in a POH? that the Cessna Skyhawk POH lists stall speeds for specific conditions due to a lack of AoA indicator. However, what's unclear to me is what the ...
10
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3answers
702 views

Why don't Transport Category aircraft have a listed Vy?

I was talking with a pilot about an inability to maintain the targeted climb rate in a particular situation and asked him what the Vy was for the jet. He curtly replied "Vy is only for Part 23 ...
0
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0answers
50 views

What is the significance of the V1 ground roll of an aircraft? [duplicate]

What is the significance of a V1 ground roll of an aircraft trying to take off? Why is minimum ground roll is measured in feet? What is the significance of VR (which is greater than V1 but less than ...
15
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2answers
565 views

Why is manoeuvring speed higher in utility category?

In a C172P, the manoeuvring speed is 99 KIAS at 2400 lbs, 92 KIAS at 2000 lbs, and 82 KIAS at 1600 lbs. However, it is 102 KIAS at 2100 lbs when in the utility category, which has a more restrictive ...
3
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1answer
296 views

How are $V_r$ and $V_2$ determined?

$V_r$ is the speed at pilot should initiate rotation on take-off and $V_2$ is the safe climb-out speed. Pilots determine them for each take-off by looking them up in a table in POH or QRH or somewhere....
12
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3answers
30k views

What exactly is VMO and how does it affect a plane when it is exceeded?

I read an article that mentioned "VMO" speeds of a 747 and that the plane, when it exceeds its VMO, shakes uncontrollably and destroys itself. I've never heard of planes doing this and the article ...
11
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2answers
2k 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. ...
2
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2answers
666 views

What is the difference between targeted airspeed and selected airspeed?

Are Targeted Airspeed and selected Airspeed the same thing? And can someone explain in what cases managed airspeed or pilot selected airspeed would be used, i.e. for different flight phases/...
17
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3answers
10k views

In a 747 is it normal for the Vr (takeoff speed) to vary greatly depending on fuel load and ambient temperature?

I was reading one of the documents linked on this question, particularly I was reading case study number 8 of this particular document. In the conclusion the author notes that the aircraft flight ...