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Questions tagged [elevator]

An elevator, in aircraft parlance, is a control surface responsible for pitching up or down.

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34
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4answers
11k views

Why do military jets sometimes have elevators in a depressed position when parked?

Why do they have elevators in such a position as if the joystick is pushed forward, even though there's nobody inside the cockpit?
7
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1answer
268 views

Why does the MCAS use the horizontal stabiliser rather than the elevators?

The Maneuvering Characteristics Augmentation System (MCAS), found, in two slightly-different variants, on the 737 MAX and KC-46, provides nose-down pitch inputs in certain very-high-angle-of-attack ...
14
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4answers
3k views

Why there so many pitch control surfaces on the Piaggio P180 Avanti?

Picture source. I have seen that there is kind of sonic aircraft like B-1B Lancer that used elevator and canard or fins at the same time for pitch control. That quite understandable because it is ...
3
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3answers
262 views

Why don’t airliners use stabilizer movement to assist with large pitch control inputs?

Most large airliners not only have elevators for pitch control, but also moveable horizontal stabilizers. The elevators are used for primary pitch control, with the stabilizers being used to trim the ...
1
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2answers
427 views

Amazon Atlas nose-down elevator deflection?

In this link I read about the crashed aircraft: The airplane then pitched nose down over the next 18 seconds to about 49° in response to nose-down elevator deflection. I feel that this is a common ...
0
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1answer
184 views

Why does the DHC-6 have only one set of elevator cables?

Air Moorea Flight 1121 crashed because its up-elevator cable broke, allowing the elevator to blow to its faired position and thus be unavailable to counteract the pitch-down moment caused by the flaps ...
7
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5answers
5k views

Why don't commercial aircraft use all-movable tail surfaces like my RC plane? [duplicate]

Many conventional RC planes use control surfaces at the tail just like the image below: You can see there is a part in front of each surface control that never moves and only the surface control ...
1
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1answer
81 views

How can I use the “control hinge-moment coefficient due to tab” for sizing a trim tab on an elevator?

I calculated the control hinge-moment coefficient due to tab by using the dimensions of a tail and its elevator. However, the trim tab dimension parameters in the calculations were approximated values ...
0
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2answers
201 views

What would happen if the elevators were set to opposite angles?

For example left elevator angle = +30 deg, right elevator angle = -30 deg. Would these settings be able to induce a rolling moment on the aircraft? What would happen with the pitch?
1
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1answer
215 views

What is the relation between hinge moment at the control surface and servo torque?

I am trying to estimate the required servo torque for my design using hinge moment at the elevator. XFOIL results were as follows- I am getting a Hinge moment of about 0.06-0.08 Nm. for the given ...
1
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1answer
156 views

Why does elevator dropdown occur in some loss-of-flight-controls accidents, but not others?

In some instances of an aircraft suffering a catastrophic failure of its primary flight controls, the loss of control force on the elevator allows said elevator to drop down under its own weight, ...
1
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2answers
384 views

Why are cambered airfoils used for horizontal stabilizers in some designs?

From what I know, usually NACA9/12 or similar symmetrical airfoils are used for the tail. Still some aircrafts use highly cambered airfoils for elevators. What are some advantages and disadvantages ...
14
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2answers
6k views

Why does the Boeing 737 have a pitot tube on the tail?

From this link: Can anyone explain why the Boeing 737 has a pitot tube for the elevators? Wouldn't the airspeed be measured the same from the front of the airplane and the tail? Is the airspeed ...
2
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2answers
411 views

What is a minimal step angle deflection for flight control surfaces?

If the flight control surfaces (ailerons, elevators, rudder) are controlled digitally by servo motors, yet disregarding the way how the input to the servo motors get generated (manually or autopilot), ...
6
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4answers
740 views

Do aerodynamic forces and moments change aircraft pitch and yaw in the same way?

Several questions on the Aviation SE site have dealt with the question: can the rudder alone turn the aircraft: This one, which was marked a duplicate of this one, which was itself marked as a ...
1
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4answers
588 views

What is the airflow across and below an elevator?

So when an airfoil creates lift. The air above the foil moves faster. This creates lower pressure in tip of the wing and relatively speaking higher pressure under the wing this create lift l. Along ...
3
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3answers
280 views

Is it correct to say “the up-elevator position decreases the camber of the elevator”?

Aft movement of the control column deflects the trailing edge of the elevator surface up. This is usually referred to as the up-elevator position. The up-elevator position decreases the camber ...
6
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2answers
782 views

How to trim in level flight when speed increases?

What is required to happen to control surfaces and trim tabs to remain trimmed in straight and level flight, as speed increases? (for a GA propelled aircraft) My manual tells me that the elevator ...
3
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1answer
304 views

What would happen if a takeoff is not rejected following an elevator malfunction?

A few weeks ago, the University of Michigan basketball team was on a plane that was in an accident. Link How bad could this have been? From my understanding the issue was here: Is this the kind of ...
1
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0answers
255 views

How much do elevators deflect on takeoff? [duplicate]

Do elevators create immediate lift off on the big airplanes? E.g., on a 737, 747, or an Airbus, I don't see elevators moving up when I see airplanes lifting off in videos. Is it just a slight up ...
9
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1answer
813 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 ...
21
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2answers
5k views

What are these holes in my Cessna 172, just in front of the elevator?

Been wondering about these for a while. Student pilot working on my PPL. When preflighting my Cessna 172 the other day, I noticed these holes just in front of the elevator. What are they for? The ...
2
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1answer
281 views

Would there be any benefit in placing the aircraft engines on the elevator (end-tips)?

Looking at the HondaJet, we can see an interesting placement of the engines. This leads me to wonder, for a slow flying aircraft how would it be affected with engines placed on the end tips of the ...
5
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2answers
4k views

What exactly is a variable incidence tailplane?

I've been reading about it regarding trim changes and such, but I don't exactly know what a VIT is? Can someone explain that to me?
8
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2answers
724 views

How do I achieve a lower stall speed, and capture potential CLmax without enough elevator control authority?

I am running some analysis on a uav, and the results I have found show that with proposed modifications I am unable to trim at my previous $c_{L\:max}$ and thus originally designed stall speed (...
4
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1answer
839 views

Is setting elevator to certain angle equal to trimming the horizontal stabilizer?

(I was trying to understand the longitudinal stability of aircraft and how it is related to elevator) If I pull the stick back by, say 2 inches, will it have the same affect as trimming the ...
5
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1answer
925 views

What are the definitions of elevator angle of attack and critical angle of attack?

Angle of attack is the angle between the chord line of the wing to the direction of relative wind. So angle of attack helps the aircraft climb. Then what is the angle between the chord line of the ...
9
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1answer
142 views

Does being out of trim affect drag?

If the aircraft is not trimmed correctly and either the pilot or autopilot is having to use constant pressure on the elevator does this increase drag?
0
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1answer
272 views

How does an elevator offload function works in fly by wire flight control systems? [duplicate]

In some fly by wire systems I found that there is no trim in the traditional sense. I believe it is because the forces that pilot feels on the stick are artificial. I was told that those fly by wire ...
4
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2answers
349 views

Why does not the lift produced by main wings create pitch moment?

Pitch moment is created by lift created by the horizontal stabilizers via the elevators. But then main wings also create lift, why does not this lift enough to create pitch moment?
9
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1answer
1k views

Where are the locations of the elevators or horizontal stabilizers in a Concorde?

I don't find the horizontal stabilizers or the elevators of a Concorde at the tail section like other aircrafts. Are they fitted beside the ailerons in the wings?
7
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1answer
2k views

What degree of elevator deflection is required to takeoff?

I've always wondered how much the elevator actually needs to deflect in order to cause rotation on takeoff for a large airliner. On videos I can rarely see the elevator moving at all. I'd really ...
5
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1answer
332 views

Is an elevon (elevator + aileron) considered as an all-moving control surface?

The delta wing on Concorde uses elevon as its control surface. Is the elevon considered as all-moving control surface?
11
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5answers
2k views

What is the point of making one control surface play the part of multiple control surfaces?

For example, flaperons (flaps + ailerons) and elevons (elevator + ailerons), are all individual control surfaces but play the roles of two different control surfaces. What is the point of making a ...
3
votes
1answer
780 views

Is there a formula to compute the elevator angle to stabilize takeoff?

I'm building a ground effect vehicle, but I'm failing to stabilize the lift-off. At a certain speed, the lift force is equal to the weight force, so the vehicle lifts off. But this implements a change ...
10
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2answers
5k views

Why couldn't Air Moorea Flight 1121 use pitch trim to land safely?

On August 9th, 2007 an Air Moorea Twin Otter crashed into the ocean. The cause of the crash was determined to be loss of pitch control after an elevator cable snapped. In my world (Cessna 152), if an ...