# Questions tagged [v-speeds]

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

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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
144 views

### Why is higher V1 preferred over lower V1 in takeoff performance calculations?

I am using a takeoff performance application that seems to prioritize a higher V1 speed whenever there is extra runway available. It does this as long as the Acceleration-Stop Distance (ASD) remains ...
95 views

### Do Vx and Vy speeds refer to IAS or TAS?

I've had this discussion with my FI: Are speeds such as Vx and Vy referring to IAS at all times or TAS that needs to be compensated for? Here's an example. Let's assume the following: Vy of my single ...
25 views

### How do you determine VMCG, if its yawing moment by the inoperative engine is only be corrected by the rudder?

The requirement of VMCG is: VMCG, the minimum control speed on the ground, is the calibrated airspeed during the takeoff run at which, when the critical engine is suddenly made inoperative, it is ...
1 vote
134 views

### Is my understanding about Balanced Field correct?

We have two definitions: Balanced Field where Takeoff Distance Required = Accelerated Stop Distance Required Balanced V1 = This is the speed where on a balanced field length (TODR=ASDR) if we have ...
1k views

### Helicopter V speeds explanation

I am reading Cat A heli procedures, and there is Vtoss speed, so what is the difference between Vx(best angle of climb speed) and Vtoss(take off safety speed) ?
1 vote
272 views

### Question about V1 Vr V2 computations

On ASA’s ATP test book they mention the following: “V1 is computed using the actual airplane gross weight, flap setting, pressure altitude and temperature.” I understand that v1 gets adjusted for ...
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
271 views

### How would Vy be adjusted for changes in gross weight?

For piston propeller aircraft, Vy calibrated airspeed[CAS] is equal to CAS for best Lift/drag at the plane's absolute ceiling, and at lower altitudes Vy increases above best L/D as excess power is ...
461 views

### Forward Slip - Which speed to maintain?

Which is the proper speed to be maintained during a Forward Slip? Near Vfe or Vref? Which one will let you lower with the shorter ground distance and why?
1 vote
137 views

### Why does the airplane manual state S1 is equal to or greater than the higher of ground minimum control speed or critical engine failure speed

I don't understand why S1 is equal to or greater than the higher of Ground Minimum Control Speed or Critical Engine Failure Speed (Vcef). I do understand that S1 has to be the lowest of Refusal Speed, ...
40k 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 ...
9k views

### 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 ...
51k 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 ...
1 vote
126 views

### Why does V2 decrease for intersection takeoff

I have noticed that the VR and V2 decreases for same FLEX when departing from an intersection runway even when sufficient stop margin is available. What is the reason for this? And also does EFB ...
570 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 ...
1 vote
536 views

### Does Indicated Stall speed increase with altitude (Coffin Corner)?

It is my understanding that Indicated Stall speed is mostly constant with altitude, the one that increases is True Stall Speed. Given that PFD show speed as IAS, how come the yellow speed range ...
2k 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 ...
425 views

### 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 ...
13k 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 ...
5k 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 ...
3k 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 ...
602 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 ...
272 views

### 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 ...
129 views

### 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 ...
4k 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, ...
5k 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: ...
1 vote
1k views

### 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 ...
3k 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 ...
639 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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### 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 ...
1 vote
385 views

### 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 ...
2k 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 ...
363 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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### 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 ...
2k 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 ...
1k 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?
1 vote
1k 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 ...
1k views

### Why does Vmca decrease with increasing altitude?

A question from a mock MEP class rating test: Many thanks for your help.
3k 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 ...
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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### 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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### 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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### 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 ...
116 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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### 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 ...
1 vote
770 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 ...
3k 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 ...