Questions tagged [v-speeds]

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

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What is the AeroVironment Helios' Kármán line?

If it's true that the NASA/AeroVironment Helios maintained level flight 96,000 ft above sea level at a maximum airspeed of 23.5 kts (43.5 km/h) I assume it must have a very high Kármán altitude, the ...
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8 votes
6 answers
3k views

What if you have a double-engine failure after V1 but before VR?

Imagine an A320 on the runway, starting its take off roll. The PM calls out "$V_1$". Just a second after $V_1$ is called out, and before $V_R$, you encounter a double-engine failure (an A320 ...
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8 votes
1 answer
398 views

Why does Vr increase with lower air density and decrease with higher air density?

Can someone explain why Vr increase with lower air density and decrease with higher air density? I read such a phrase in my ATPL(A) performance textbook, but without further explanation. As far as I ...
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What are the V speeds for a Piper Super Cub 180HP with an upgrade to 61 gallons fuel capacity?

I fly a Piper Super Cub 180HP with upgraded 61 gallons, 30.5 gallons usable a side. The POH and everywhere I look online I find POHs for Cubs with 150hp and 36 gallons TOTAL. I was wondering if anyone ...
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0 votes
1 answer
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Why is the definition of $V_{S1}$ vague wrt configuration?

The definition of $V_{S1}$ is the stalling speed or the minimum steady flight speed obtained in a specific configuration from 14 CFR §1.2 Abbreviations and symbols. Why is this vague in terms of the ...
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4 votes
1 answer
861 views

When is Vmo/Mmo applicable?

I have read that for most planes Vmo (maximum operating speed) is the limitation below 25000ft and Mmo (maximum operating Mach number) is the limitation above 25000ft. Is it correct to say this and, ...
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3 votes
0 answers
91 views

Matching the Drag Equation to Real Airplane Data

I am trying to compute airplane performance for a piston-driven airplane with constant speed prop using the standard equations for Lift, Thrust and Drag. I have found that there are a couple of useful ...
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2 votes
2 answers
982 views

What are the approach speeds for each flap setting in a Cessna 152?

I am still trying to understand how the approach speeds for different flap speeds work. I cant find it in the handbook but I want to know the different approach speeds for the following flap settings: ...
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2 votes
2 answers
2k views

Why would I want to lower the stall speed?

Why would a cargo pilot for example want to dump fuel to lower the stall speed? I understand that lowering the weight decreases the stall speed, meaning it is "easier" for the plane to reach ...
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3 votes
1 answer
235 views

What happens to Vyse and Vxse above the OEI ceiling?

An EASA ATPL question/answer insists, counterintuitively, that a twin which loses an engine and must drift down will find its least rate of sink at Vxse. I've been trying to understand this, but haven'...
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4 votes
2 answers
2k views

Do manufactures list the maximum speed of an aircraft based on its theoretical maximum speed or dive speed?

I know that the absolute maximum velocity of an aircraft is based on the thrust available. However the aircraft is usually limited beforehand by other speed limits such as dive speed and Mach Never ...
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How to calculate best glide speed at a 30 degree bank?

The Best Glide speed is the indicated airspeed that guarantees the maximum glide distance during an engine out scenario. However, the landing straight ahead option after an engine failure may not be ...
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7 votes
2 answers
993 views

How does an inoperative Anti-Skid affect V speeds?

I am trying to figure out why is it that when you have an inoperative anti-skid system, the calculated V Speeds are lower? I'm trying to see this from a performance perspective, could this be due to ...
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9 votes
1 answer
280 views

When was the concept of V1 introduced?

When was V1 speed first introduced? Was it the result of a particular accident or series of accidents?
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2 votes
2 answers
456 views

What is the takeoff decision speed (V1) for a Gulfstream G500?

Can someone tell me what is the decision speed (V1) of the Gulfstream G500? Is it 200kt as shown in this picture?
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1 vote
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What forward airspeed produces maximum rate-of-climb in helicopters?

Lift in a helicopter increases with airspeed (from zero IAS up to some Vmax). But in contrast to fixed-wing aircraft a helicopter can generate lift at zero airspeed. Is there a formula for the ...
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1 answer
535 views

Why does Vmca decrease with increasing altitude?

A question from a mock MEP class rating test: Many thanks for your help.
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1 vote
2 answers
609 views

Where does an FMS wind information comes from to calculate V approach?

To calculate the V approach the FMS is using a wind either taken by the ADIRS or inserted on APPR PERF page. At first I will say that it takes the wind inserted by the crew, but I am not completed ...
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9 votes
2 answers
3k views

How can an aircraft’s maximum design operating speed be greater than its never-exceed speed?

According to this AAIB report on a June 2009 mid-air collision between an RAF Grob Tutor and a glider, the Tutor’s maximum design operating speed (VDO) is greater than its never-exceed speed (VNE): (...
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3 votes
3 answers
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What is physics explanation for minimum sink rate airspeed?

I did some research on Minimum Sink Rate, and saw much information defining it, (such as it is the speed at which the aircraft will remain in the air for the longest time, etc.) and how it is ...
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9 votes
4 answers
2k views

How can best glide speed be lower than best rate of climb speed?

I was looking up V-speeds for C172. I don't have easy access to an official copy of the POH, but online I found: $V_y$, best rate of climb speed (at sea level): 76 KIAS (p22) $V_{glide}$, maximum ...
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Space Catapault Model [closed]

A secretive space catapault is said to be in progress. For the sake of mathematical simplicity, assume the launch vehicle is one kilogram point-mass and to be placed in geosynchronous orbit. What ...
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11 votes
3 answers
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Has the "Foote takeoff" technique really existed, and how did it work?

Reading The Crash Detectives: Investigating the World's Most Mysterious Air Disasters by Christine Negron, I came across the following description, in relation to some early de Havilland Comet ...
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-5 votes
1 answer
172 views

What is the procedure for a fast landing that is too slow for go-around? [closed]

Say an aircraft (A320 or similar) on landing, hits the tarmac way too fast and on a short runway, less than V2 but around V1 or slightly over. This could happen if a pilot had recently moved from ...
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4 votes
1 answer
112 views

Is there a V speed for the point an aircraft starts an ascent at 0 angle of attack?

Some aircraft with an angle of incidence or cambered airfoils are capable of climb without any angle of attack, Is there a V speed for the speed at which an aircraft starts a positive climb?
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3 votes
0 answers
103 views

What were the typical rotation and landing speeds of the X-29?

Looking online through all the available literature, I could not find the typical rotation ($V_r$), landing or even stall speed of the experimental forward swept wing X-29 aircraft. I'm curious to ...
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1 vote
1 answer
431 views

Exceeding VLO and by how much is too much?

Piper Seminole (PA-44-180) VLO (max gear retraction speed) is 109 KIAS. I've heard that manufacturer published limitations are significantly lower than actual structural and system limitations. What ...
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7 votes
2 answers
2k 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 ...
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5 votes
2 answers
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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'...
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4 votes
2 answers
617 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, ...
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7 votes
1 answer
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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 ...
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3 votes
1 answer
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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 ...
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3 votes
2 answers
281 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 ...
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2 votes
3 answers
161 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 ...
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6 votes
1 answer
425 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 ...
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1 vote
2 answers
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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 ...
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5 votes
2 answers
1k 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 ...
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1 vote
2 answers
21k 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 ...
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5 votes
2 answers
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How to calculate the best glide speed if there is none on the POH?

I am studing the POH of Seneca II and could not find the Best Glide Speed. Where can I get this information from? I thought to multiply Vs clean for 1.4 to get an approximate result but I am not sure ...
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1 vote
1 answer
411 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 ...
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2 votes
4 answers
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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 ...
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2 votes
2 answers
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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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1 vote
3 answers
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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 ...
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1 vote
3 answers
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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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1 vote
3 answers
3k 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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0 votes
1 answer
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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 ...
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-2 votes
1 answer
1k 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?
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7 votes
2 answers
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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 ...
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3 votes
2 answers
725 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 ...
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1 vote
1 answer
170 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 ...
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