Level of turbulence for VA?

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PPL747

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Hi I'm very new pilot and one thing that keeps on bothering me is at what level of turbulence you should slow down to below maneuvering speed. The other day I was flying and it was some light turbulence here and there and I got concerned about being above VA. Is there a formula to follow? Is it something you feel by air? Would a VFR pilot not flying near thunderstorm clouds encounter it?
Please any info would be helpful
 
It is important to understand what Va actually means. Even at Va you can break a plane..

Personally, I'll slow down if it starts getting unpleasant. Have only really had to do this a few times, once in Banning Pass, the other times in Owens Valley

"The wing will stall before it breaks" - even in the worst bumps I've felt I've never heard the stall chirp, suffice to say planes can handle a lot. I highly doubt a routine training flight would ever typically need to slow to Va. Also worth noting that at least in the PA28 I sometimes rent I have never been actually able to cruise as fast as Va..
 
It changes with weight too, so I calculated a table that I keep in the plane for reference. I did the same thing for best glide speed.
 
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Tantalum said:
I have never been actually able to cruise as fast as Va
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ain't that the truth lol...

OP - its possible you will see some speed while a descent and you could get into bumpy air, go with your comfort level and slow the plane down, the faster you run through bumpy air the more unpleasant it becomes.
 
I think you are confusing Va and Vno.

Va is the maximum speed at which full abrupt control deflection will not break the airplane.
Vno is the maximum speed at which a turbulence vector of a specified amount (I think it is 30m/sec) will not break the airplane.
 
I'm deep in the yellow at cruise speed in my Mooney.
 
WannFly said:
there is no need to rub it in
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C Model Mooney the yellow is pretty low. Well, relative to Mooney speeds anyway. It's actually kinda a negative, not a positive. Not that the cruise speed isn't very nice. ;)

Yellow starts at 150mph (130 knots)
Maneuvering is 132mph (115 knots)

My typical TAS is 160-170mph (140-150 knots)
 
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Salty said:
I'm deep in the yellow at cruise speed in my Mooney.
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Archer II with a new-ish engine. High pressure, low temperature. Full rental power...

-Skip

(yes I know it is showing a slight negative Vspeed, but this was a transient.... honest!)
 

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smv said:
I think you are confusing Va and Vno.

Va is the maximum speed at which full abrupt control deflection will not break the airplane.
Vno is the maximum speed at which a turbulence vector of a specified amount (I think it is 30m/sec) will not break the airplane.
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Yes and no...Above Vno is “smooth air” only. Rough Air speed, Vb, provides the stall protection before the wing over stresses due to turbulence. Most of the light airplanes I’ve flown list Va as “rough air or maneuvering speed”, so the same speed provides the rough air protection as well as the control deflection protection.

specifically for the OP’s question, if you start approaching the g-limits of the airplane, you need to slow down. +3.8/-1.52 Gs is a LOT. as others have said, you’ll probably be uncomfortable or even scared long before it’s rough enough to damage the airplane.
 
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· Turbulence

o Slow down to Va. For every 20% less than gross, lower the Va with 10%

o Penetration speed Vb: Vs1 x 1.7 .

Vs1 stuff in
Vs0 stuff out
 
MauleSkinner said:
Yes and no...Above Vno is “smooth air” only.
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Which is why I said
"Vno is the maximum speed at which a turbulence vector [non-smooth air] of a specified amount (I think it is 30m/sec) will not break the airplane."
 
smv said:
Which is why I said
"Vno is the maximum speed at which a turbulence vector [non-smooth air] of a specified amount (I think it is 30m/sec) will not break the airplane."
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50 fps
 
smv said:
Which is why I said
"Vno is the maximum speed at which a turbulence vector [non-smooth air] of a specified amount (I think it is 30m/sec) will not break the airplane."
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But I don’t think he was confusing Va with Vno...I think he was confusing Va with Vb without knowing that Vb exists.
 
Va has squat to do with turbulance. It's the point where certain control movements (specifically pitch up) will stall the aircraft before bending it.

From AC 23-19A:

48. What is the design maneuvering speed VA? a. The design maneuvering speed is a value chosen by the applicant. It may not be less than Vs√ n and need not be greater than Vc, but it could be greater if the applicant chose the higher value. The loads resulting from full control surface deflections at VA are used to design the empennage and ailerons in part 23, §§ 23.423, 23.441, and 23.455. b. VA should not be interpreted as a speed that would permit the pilot unrestricted flight-control movement without exceeding airplane structural limits, nor should it be interpreted as a gust penetration speed. Only if VA = Vs √n will the airplane stall in a nose-up pitching maneuver at, or near, limit load factor. For airplanes where VA>VS√n, the pilot would have to check the maneuver; otherwise the airplane would exceed the limit load factor. c. Amendment 23-45 added the operating maneuvering speed, VO, in § 23.1507. VO is established not greater than VS√n, and it is a speed where the airplane will stall in a nose-up pitching maneuver before exceeding the airplane structural limits.
 
flyingron said:
Va has squat to do with turbulance. It's the point where certain control movements (specifically pitch up) will stall the aircraft before bending it.
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True, but many light planes use it for both...it’s placarded as “rough air or maneuvering speed”.
 
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Salty said:
Maneuvering is 132mph (115 knots)
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Interesting, the Archer III at the club is 113 knots.. pretty close actually. The Mooney's solid wing spar can probably handle a lot more. How often do you find you have to slow down out of the yellow for bumps?
 
Tantalum said:
Interesting, the Archer III at the club is 113 knots.. pretty close actually. The Mooney's solid wing spar can probably handle a lot more. How often do you find you have to slow down out of the yellow for bumps?
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Honestly, in Florida weather about the only time I have to deal with it is ducking between thunderstorms in the summer. When I go other places, I’m usually above any turbulence. Maybe a half dozen times in the last 200 hours.
 
flyingron said:
Va has squat to do with turbulance. It's the point where certain control movements (specifically pitch up) will stall the aircraft before bending it.
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Precisely why the question was in error from the beginning. I will not go as far as to say it was a "stupid" question, but it does show the OP's lack of understanding of the different V speeds (and he is apparently not alone).

Vno is where the green arc ends and the yellow arc begins. It is clearly marked on the ASI. I have yet to see an ASI with Va marked. (Cue someone with an example...:D)
 
smv said:
Precisely why the question was in error from the beginning. I will not go as far as to say it was a "stupid" question, but it does show the OP's lack of understanding of the different V speeds (and he is apparently not alone).

Vno is where the green arc ends and the yellow arc begins. It is clearly marked on the ASI. I have yet to see an ASI with Va marked. (Cue someone with an example...:D)
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Why would the ASI have to be marked with it?
 
smv said:
You win. I refuse to engage with someone being so obviously intentionally obtuse.
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If clarifying a statement is obtuse, what does that say about the statement itself?

you clearly have no idea what the OP is talking about, so he and everyone else must be confused.
 
"In extremely rough air, as in thunderstorms or frontal conditions, it is wise to reduce the speed to the design maneuvering speed." —PHAK.
 
If my head starts hitting the ceiling.... then it’s time. :)
 
Archer placard requirement: “ROUGH AIR OR MANEUVERING SPEED-127 MPH.”
Maule M4 placard requirement: “ROUGH AIR OR MANEUVERING SPEED-125 MPH.”
 
Up front. Low time pilot, turbulence makes me nervous as well and would love ball park speeds for flying in turbulent air. (To hang my hat on for starters. Ex. Approach speed aim for Vs0 x 1.3. Later to refine as experience teaches otherwise).
Always thought of the Va as: "Do not make full or abrupt control surface movements above this speed", exactly what I might do when my head hits the canopy.
So the stupid question then is to what initial speed (referenced to say Vs) should I slow down to protect the aircraft, never mind my head?
 
21541803 said:
Up front. Low time pilot, turbulence makes me nervous as well and would love ball park speeds for flying in turbulent air. (To hang my hat on for starters. Ex. Approach speed aim for Vs0 x 1.3. Later to refine as experience teaches otherwise).
Always thought of the Va as: "Do not make full or abrupt control surface movements above this speed", exactly what I might do when my head hits the canopy.
So the stupid question then is to what initial speed (referenced to say Vs) should I slow down to protect the aircraft, never mind my head?
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Does your aircraft not have a published Va?

Va is usually, but not always, Vs x sqrt(n), where n is the limit load factor -- 3.8 for normal category aircraft. Be sure to use calibrated to do the math then convert to indicated.
 
Someone wanting to understand this issue at a deeper level can look at the Vg diagram, and related discussion, in Chapter 5 of the Pilot's Handbook of Aeronautical Knowledge.

Chapter 5 is Aerodynamics. The discussion of Load Factors begins on page 5-33. The Vg diagram is on page 5-38.

The Vg diagram shows how the limit airspeeds are developed and how staying below them protects the airplane. You'll also see that Va only protects the airplane from positive-g loading, not negative-g.

https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/
 
I love how pedantic this place gets

when all is said and done, in layman's terms, I think OP just wants to make sure the plane won't fall apart if he hits turbulence.. and if he should slow down at all

Maneuvering speed is typically lazily taught as "the plaine won't break if you're going slower than this"

To answer his question.. there's no real specific formula.. stay out of the yellow in rough air

FWIW, using Va as a proxy for a "safe speed" in severe turbulence is not the worst thing to do
 
My airspeed in moderate and severe is lower than Va. I judge speed by how abrupt the direction changes are. My Va is 123 but flying at 100 suits me fine when the bumps start to hurt.
 
Tantalum said:
I love how pedantic this place gets

when all is said and done, in layman's terms, I think OP just wants to make sure the plane won't fall apart if he hits turbulence.. and if he should slow down at all

Maneuvering speed is typically lazily taught as "the plaine won't break if you're going slower than this"

To answer his question.. there's no real specific formula.. stay out of the yellow in rough air

FWIW, using Va as a proxy for a "safe speed" in severe turbulence is not the worst thing to do
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Updrafts near thunderstorms can exceed 50fps by a wide margin. You want to be below Va in severe turbulence. For light or moderate Vno should be fine, though it depends on what you call moderate.
 
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