Which Flight Control Turns The Plane?

Daleandee

Daleandee

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Dale Andee
This has been hashed over many times before. In this short video Spencer Suderman gives us his take on it. His answer may surprise you. Do you agree?

 
Oh man, not this again. He's also wrong. What happens with plane that has no elevator? It can't turn? I can lock the elevator and it will turn.
 
This one seems to have no trouble with rudder only.


Seems like I have see Aileron only models but they are much more rare as In I didn't find a google search example.

Edit: I didn't watch the whole thing before posting. Flew fine, looks like could have landed better. But back when single channel radios were what most hobbiests could afford single channel rudder only was actually fairly common.

Brian
 
Years ago I did a flight review when the instructor gave a simulated locked stick. I was able to fly the plane and make an approach to landing using only power, rudder, and trim.
 
Use all the controls to make it turn in a coordinated fashion. You need all three of those primary controls, plus the throttle if you're going to turn steeply. What's so hard about that?
 
Didn’t watch Spencer’s vid but the last time we talked about the subject, the guy (Rich) in the vid equated turning to a loop. Yes, that would be a circular motion around an axis but turning in the horizontal axis is completely different than a loop. A loop is a poor example of a turn since 99 % of us aren’t turning in the vertical.

In the horizontal, the horizontal component of lift (wings) is the primary factor. All the elevator does is vary the AoA, thus increasing / decreasing the turn rate. In the horizontal, all flight control surfaces contribute to the turn. To say that the elevator is what actually turns the aircraft is absurd.

A helicopter has no elevator and yet it turns in the horizontal. That’s because the rotor system is no different than the wings of an aircraft. A vertical component and a horizontal component. Vertical obviously acts opposite weight and the horizontal, turns the aircraft.
 
dmspilot said:
None of them do, the horizontal component of lift turns the airplane. Private pilot knowledge, it's even on the written.
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Not true. If you fire the lateral thrusters on a forward moving space ship, does that make ithe ship turn? A force will cause a linear acceleration. Turning requires a rotation about its vertical axis. In other words you need an angular momentum.
 
sarangan said:
Not true. If you fire the lateral thrusters on a forward moving space ship, does that make ithe ship turn? A force will cause a linear acceleration. Turning requires a rotation about its vertical axis. In other words you need an angular momentum.
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A force causes a linear acceleration, yes. But unless it's applied directly through the center of mass it will also cause an angular acceleration. In a constant rate turn, however, the angular acceleration is zero once the turn rate is established; then the sideways linear force is all that's needed to maintain the curved flight path.
 
sarangan said:
Not true. If you fire the lateral thrusters on a forward moving space ship, does that make ithe ship turn? A force will cause a linear acceleration. Turning requires a rotation about its vertical axis. In other words you need an angular momentum.
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Space ships are not flying. They are in a vacuum. You put a thruster on an airplane it will not respond the same way as your spaceship.

you don’t understand how this thing works. Horizontal component of lift is what turns the airplane. How you get that out of the aircraft and what airfoil generates it can vary but that’s the magic that turns the airplane.
 
Yep, elevator. No need to watch further. More properly, the elevator/horizontal tail surfaces together change direction of flight. If you could throw a switch to turn off gravity, a properly trimmed airplane will start turning, doing 360s in a vertical plane. Gravity just keeps it from happening during straight and level.
 
What about flat turns. We did flat turns in the Hawkeye. Uncoordinated (wings) level turn. George would do it too. Sometimes.
 
The wing's horizontal lift component gets the airplane moving into a turn. The tailfeathers get the fuselage lined up with the direction of flight, and both rudder and elevator are involved. Elevator is also necessary to counter the nose-drop caused by the turn's increased induced drag. The rudder can also contribute to that drop.

All the controls do all the work. It's an old argument. Another is the power vs. pitch argument for speed and altitude. You try to separate them and you just create confusion.

Flat turns use prop thrust and fuselage lift/drag. Good way to die in the pattern.
 
The more you try to simplify concepts the less accurate those concepts become. Forces and moments turn an airplane. Control surfaces are one way of manipulating those forces and moments, but not the only way, and no single control surface is the *only* way to manipulate a force and/or moment in any particular manner. It is possible to turn an airplane without an elevator. It is possible to bank an airplane without ailerons. It is possible to yaw an airplane without a rudder. All three of these are done regularly and easily.

Nauga,
momentarily
 
dtuuri said:
Yep, elevator. No need to watch further. More properly, the elevator/horizontal tail surfaces together change direction of flight. If you could throw a switch to turn off gravity, a properly trimmed airplane will start turning, doing 360s in a vertical plane. Gravity just keeps it from happening during straight and level.
Click to expand...

Nope. I can put a control lock on the yoke to keep the elevator from moving, and can still get the plane to turn. Can also keep it locked and do it with rudder also. And V-bonanza don't have elevators, so I guess they only ever fly in straight lines.
 
Dana said:
A force causes a linear acceleration, yes. But unless it's applied directly through the center of mass it will also cause an angular acceleration. In a constant rate turn, however, the angular acceleration is zero once the turn rate is established; then the sideways linear force is all that's needed to maintain the curved flight path.
Click to expand...

Except, the center of mass is nearly always in front of the center of lift. So when the lift vector is tilted, then the angular momentum will turn the nose in the wrong direction.
 
Dan Thomas said:
The wing's horizontal lift component gets the airplane moving into a turn. The tailfeathers get the fuselage lined up with the direction of flight, and both rudder and elevator are involved. Elevator is also necessary to counter the nose-drop caused by the turn's increased induced drag. The rudder can also contribute to that drop.

All the controls do all the work. It's an old argument. Another is the power vs. pitch argument for speed and altitude. You try to separate them and you just create confusion.

Flat turns use prop thrust and fuselage lift/drag. Good way to die in the pattern.
Click to expand...

Yes, tail feathering into the wind is a critical aspect of turn. If the airplane were in vacuum, a horizontal force will not turn the nose. It will only laterally accelerate the airframe.
 
sarangan said:
Except, the center of mass is nearly always in front of the center of lift. So when the lift vector is tilted, then the angular momentum will turn the nose in the wrong direction.
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How would you describe the aerodynamics of the airplane in post #3 which is clearly able to turn, climb, and descend without an elevator? Hint: It has everything to do with stability and nothing to do with an elevator.

Nauga,
who places his poles carefully
 
X3 Skier said:
If I stick my arm out of the Ercoupe window, the Ercoupe turns. Is my arm a control surface?

Cheers
Click to expand...
How about that. Many pilots did that back in the BirdDog days. You can stick your arms out both windows and double the aileron effectiveness.
 
When you’re in a knife edge, do you call the rudder an elevator and vice versa?
 
EdFred said:
I can put a control lock on the yoke to keep the elevator from moving, and can still get the plane to turn.
Click to expand...
And your point is... what? If you want to turn faster, take off the lock, bank the plane and use the elevator to lever the wing around. The wing has a much bigger surface to deflect the air, so why would anybody ordinarily use something else, not that it would be impossible to accomplish to a much lesser degree?
 
eman1200 said:
I thought the turn signal enables you to turn.
Click to expand...

Based on what I see when driving these days, 90% of cars don’t seem to have turn signals but they still turn, sometimes right in front of me. So you’re wrong.

Cgeers
 
I turned around the gas pump Saturday by holding full left rudder and some left brake.
 
Daleandee said:
Years ago I did a flight review when the instructor gave a simulated locked stick. I was able to fly the plane and make an approach to landing using only power, rudder, and trim.
Click to expand...

this is from last summer.
http://www.kathrynsreport.com/2021/12/flight-control-system-malfunction.html

I was towed by this plane and pilot about a week before this accident.
This was very close to a Great Landing, with no damage.

I also know a pilot/CFI that landed an Aeronca Champ after the Aileron Jammed. Cable pully broke and cable jammed.

Brian
CFIIG/ASEL
 
dtuuri said:
And your point is... what? If you want to turn faster, take off the lock, bank the plane and use the elevator to lever the wing around. The wing has a much bigger surface to deflect the air, so why would anybody ordinarily use something else, not that it would be impossible to accomplish to a much lesser degree?
Click to expand...
The point is the elevator doesn't turn the plane.
 
sarangan said:
Except, the center of mass is nearly always in front of the center of lift. So when the lift vector is tilted, then the angular momentum will turn the nose in the wrong direction.
Click to expand...
Not quite. The center of mass is in front of the wing's center of lift, but in level flight the center of mass is exactly at the entire aircraft's center of lift, otherwise it would be accelerating in pitch.
 
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