Questions tagged [sideslip]

A flight condition where an aircraft's direction of motion is not aligned with its longitudinal axis, causing the aircraft to "slip" sideways through the air.

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What is a rough estimate for a sideslip angle for a Dutch Roll?

I previously asked: Is there a regulatory maximum side slip angle for commercial aircraft? Apart from a regulatory maximum, can anyone give me a rough value to assume for sideslip angle during a dutch ...
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2 votes
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Is there a regulatory maximum side slip angle for commercial aircraft?

Hi am currently trying to run Dutch roll simulations for a proposed 35 seat twin engine turboprop aircraft. I was just trying to work out what sideslip angle might be appropriate to use. Is there a ...
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What happens to Lift and Drag on aircraft (and its components) when sideslip is increased gradually from 0 degrees to 90 degrees?

I possess an Aerospace Engineering background, and work as a Aerospace structural analyst at a local firm. A portion of my job is dedicated to determining the critical conditions that the aircraft and ...
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5 votes
4 answers
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Viable to slip onto the center line?

One of the constant problems of aviation is drawing onto the center line on final. Either due to a bad rollout or due to crosswinds a pilot often finds that the aircraft is not on the center line for ...
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3 answers
163 views

Forward slip dynamics

I am perplexed on the dynamics of the forward slip. I am illustrating here: The intended ground flight path is axis +y, and the plane is forward slipping by banking right + left rudder. In order to ...
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1 vote
1 answer
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Do redundant angle of attack and sideslip sensors use a voting mechanism, or do they display data directly?

In civil transport aircrafts (featured with dual/triple redundancy), how does airplane's Airflow angle (AoA/AoSS) sensor measurements read by the pilot? By using voter mechanism as used for airspeeds ...
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12 votes
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Why do flying wires hum louder in a sideslip?

Page 50 of the Feb. 2021 issue of the EAA's magazine Sport Aviation reports that Like any good vintage airplane, the Sea Bird likes to fly coordinated, and the flying wires will sing out loud if the ...
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1 vote
5 answers
487 views

What causes the ball to not be centered in a slip/skid?

I've reviewed quite a few questions on this forum including Forces in a slipping turn is-this-vector-diagram-of-the-forces-at-play-in-turning-flight-correct what-does-the-balance-ball-actually-...
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Does the routine flown by the Thunderbirds in the F-16 feature true sustained knife-edge flight?

Does any aerobatic routine flown by the USAF Thunderbirds in the F-16 feature true sustained knife-edge flight? By "true sustained knife edge flight" we mean that the aircraft is maintaining ...
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2 votes
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390 views

Is drift and sideslip angle the same in the accompanied figure?

Consider the following figure: Initially aircraft is moving along dotted line. But due to wind, aircraft ground track is changed to solid line but body still pointing parallel to dotted line. I've ...
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In a full-rudder sideslip in a Schweizer 2-22 or 2-33 glider, is the descent rate higher at 50 mph airspeed than at 60 mph airspeed?

Is it really true that in a full-rudder sideslip in a Schweizer 2-22 or 2-33 glider, the descent rate is higher at 50 mph airspeed than at 60 mph airspeed? Likewise, is it really true that in a full-...
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Why is there a a nose-up pitching tendency during a forward slip in a Cessna 172?

Why is there a tendency for the nose to pitch-up during a forward slip in a Cessna 172 (According to the TC Flight training manual)? Quote: "If full rudder is used, considerable aileron pressure ...
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Why does a steady-state non-zero body yaw and/ or roll rate induce side force?

An answer on ASE states The presence of steady-state non-zero body yaw and roll rate induces side force ($C_{y_p}$ and $C_{y_r}$). What is a non-mathematical explanation of why this is so? Is it ...
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3 votes
3 answers
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Why does a banked aircraft create sideslip?

Below is an excerpt from Raymer (Aircraft Design) where he explains the dihedral effect. He states that a banked aircraft (due to say a roll disturbance) will have a sideslip which leads to a ...
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How are coefficients of equation of sideslip angle in the paper "A general Solution to the Aircraft Trim Problem" calculated?

I am sure many of you guys must have read the paper, "A General solution to the Aircraft Trim Problem" by Marco, Duke and Bernt. I am working with the turning of the Aircraft and I am not able to ...
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2 answers
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Mushing glide vs forward slip sink rate

Source: Wolfgang Langewiesche - Stick and Rudder; An Explanation of the Art of Flying I ran across a mushing glide in Wolfgang Langewiesche's - Stick and Rudder; An Explanation of the Art of Flying ...
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Why should one not slip a Cessna 172 with flaps extended?

The POH strongly recommends not slipping the AC with full flaps...why? It seems natural in a crosswind approach to allow the horizontal lift component to cancel the airmass movement across the ...
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Forces in a slipping turn [duplicate]

I have trouble understanding why the ball (on the turn & slip indicator) falls into the turn e.g. drop to the left when aircraft is rolled left, when in an uncoordinated turn (slipping turn). What ...
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What is missing from these diagrams of the forces in slips and skids?

See these images that are widely reproduced in many different on-line ground school materials. A) Is the magnitude of the wing's lift vector illustrated correctly in each of the three cases? Should ...
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What does the balance ball actually indicate?

Given answers and comments from a previous question, I realize that I need to clarify what the ball actually measure. I think it does not measure side slip but sideways acceleration, but I'm not quite ...
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1 vote
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How does sideslip indicator react during crosswind?

I will basically consider two types of sideslip indicator: the yaw string and the marble/ball inside a curved tube. I don't know the exact aeronautical term for both and I don't know if other sideslip ...
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Is it possible to calculate lateral acceleration from pitch/yaw/roll rates?

Can you calculate an aircraft's lateral acceleration from the aircraft's yaw, pitch and roll rates? If so, how? This is to implement a digital slip indicator.
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4 votes
1 answer
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Finding Angle of Attack/Angle of Sideslip using East/North/Up Coordinates

I've got a set of data that includes: x rate, y rate, z rate (all ENU) which I'll call xd, yd, zd. roll, pitch, yaw (which I'll call ϕ, θ, ψ) roll rates, pitch rates, yaw rates I'm looking at some ...
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7 votes
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Why does a turn and slip indicator matter?

I'm studying the principles of flight, and I'm having some unanswered questions in my mind regarding the turn and slip indicator. I'm reading that a turn and slip indicator displays the slip or skid ...
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Is a high alpha sideslip possible and safe?

Is a high alpha sideslip possible and safe? We use a sideslip to increase drag when trying to reduce altitude before landing on a short runway, etc., which is crossing your rudder and ailerons, to ...
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1 vote
2 answers
275 views

At what angle-of-attack (sideslip angle) would a symmetric vertical fin plus a deflected rudder have a lift coefficient of exactly zero?

For rudder deflection angles of 5, 10, 20, 30, and 45 degrees, at what (negative) angle-of-attack does a fin-rudder combination (including dorsal fin if present) have a lift coefficient of exactly ...
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2 votes
2 answers
182 views

Sideslip vs Freestream Azimuth Angle

Why is the sideslip angle, $\beta$, defined as $$\beta=sin^{-1}\left(\frac{v}{|{\bf v}|} \right)$$ and not the same as freestream azimuth angle $\psi$ $$\psi=tan^{-1}\left(\frac{v}{u} \right)$$ ...
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9 votes
5 answers
636 views

Why does elevator input move the turn coordinator ball in steep turns?

When practicing steep turns, I'm running into an unusual phenomenon. If the airplane is losing altitude in coordinated flight and I apply aft stick pressure to pitch up and correct, I notice that the ...
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2 votes
5 answers
893 views

Which way (if at all) do the ailerons need to be deflected in a full-rudder sideslip in a Cessna 152 or 172?

Do you typically have to maintain an aileron deflection in a constant-heading full-rudder sideslip in a Cessna 152 or 172? If so, in which direction? And why -- what is the source of the roll torque ...
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In which direction will an aircraft drift after taking off in a crosswind?

Assuming the pilot applies the appropriate crosswind flight controls (see below) during takeoff and rotation, and releases those flight controls after the aircraft leaves the ground, in what direction ...
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4 votes
2 answers
620 views

How can using split throttles help when landing twins in crosswinds?

In General Aviation light twins, when landing in heavy crosswinds, what are some considerations to using asymmetric (or Split) throttles to induce a sideslip, to align the fuselage with the ground ...
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2 votes
3 answers
3k views

Is there a specific relation between sideslip angle and yaw rate OR how sideslip angle depend on yaw rate?

Since, yaw rate is controlled via rudder and sideslip angle can also be controlled by rudder, I want to know if there is any dependence of sideslip angle on yaw rate in fly by wire aircraft as I am ...
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16 votes
4 answers
3k views

Is it dangerous to do a skidding turn to lose altitude without increasing airspeed?

I was taking some lessons in a light sport aircraft in South Africa a few years back, my instructor taught me something which I had never seen or heard of before or since. We went through an emergency ...
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5 votes
4 answers
3k views

How is a sideslip maintained (aerodynamically)?

(Public domain image that I've modified.) The initial rudder deflection to the left creates a side force that points right and yaws the plane to the left. NASA puts it this way: For the vertical ...
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10 votes
1 answer
1k views

What is the relationship between the UH60 Blackhawk stabilator function lateral sideslip and pitch coupling?

I'm having a hard time understanding the correlation between the wind gusts (where are they coming from, what are they affecting) and why, in a nose left situation, the stabilator is driven down. I ...
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18 votes
1 answer
1k views

Does slipping in turns allow higher climb rates?

Sailplanes, among others, use a cotton string to show the sideslip angle. I've often heard that while circling in thermals the cotton string should show a slight slip angle to climb faster. This ...
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3 votes
1 answer
474 views

In a non-symmetric turn, how do the side slip angle and thrust side slip angle affect the equations of motion?

I'm doing a problem on Flight Mechanics in which a banked turn is performed. The center of gravity of the aircraft is always within an horizontal plane. In order to write the dynamic equations, I ...
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6 votes
3 answers
3k views

What is the direction of the sideslip induced by roll on a conventional aircraft?

For the sake of this question let's assume that the considered aircraft is an A320. The question is what is the sign of the aerodynamic $C_{n_q}$ coefficient? In another word, when the aircraft starts ...
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25 votes
3 answers
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Why does a T-tail produce a pitch-down moment in sideslip?

Here is something which I did not find in any book, but confirmed in several wind tunnel and flight tests: A T-tail causes a strong nose-down moment in sideslip. This can even be observed in a ...
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