Turn Coordinator vs. Turn-and-Bank

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photofly
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Turn Coordinator vs. Turn-and-Bank

Post by photofly »

While surfing plane pr0n on Wikipedia, I saw this picture of the panel of a Caravan:

http://upload.wikimedia.org/wikipedia/c ... ockpit.JPG

I noticed that both pilot stations had a TC rather than a T&B. Since it's a relatively new aircraft, I guess that means someone made a positive choice to install the older style instrument rather than the newer.

I know the mechanical differences between the two, and I know (for example) that in still air it's easier to maintain wings level on partial panel instruments with the T&B. What are the advantages of a TC and why would someone specifying an aircraft panel choose one?
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Colonel Sanders
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Re: Turn Coordinator vs. Turn-and-Bank

Post by Colonel Sanders »

I can't speak for anyone else, but I personally
prefer the needle to the wings, because the
needle measures only yaw.

The wings was invented for cheap autopilots,
canting the gyro slightly to pick up a bit of roll.

I think this question is a bit subjective, like
"which is a better colour - red or blue?"

PS If you want to make partial panel easier,
get a vertical card compass.
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Re: Turn Coordinator vs. Turn-and-Bank

Post by Sidebar »

Colonel Sanders wrote:I can't speak for anyone else, but I personally prefer the needle to the wings, because the needle measures only yaw.
I think the needle measures rate of turn and the ball indicates yaw. We used to call them a turn and slip indicator.
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photofly
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Re: Turn Coordinator vs. Turn-and-Bank

Post by photofly »

Ball just measures the local direction of acceleration - neither slip nor yaw.
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Re: Turn Coordinator vs. Turn-and-Bank

Post by Justjohn »

Guys, The turn coordinator is the newer, more modern instrument ( I didn't say better ). Not the other way around. So the Caravan in question has the newer instrument in it.


Edit: I should have looked at the pic before I posted. The panel pictured has the older TURN & BANK instrument. The turn coordinator is still the newer, modern instrument.
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photofly
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Re: Turn Coordinator vs. Turn-and-Bank

Post by photofly »

Good catch, thanks. I got the names the wrong way round.

But what's the advantage of the older (needle) vs the newer (wings) instrument?
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Re: Turn Coordinator vs. Turn-and-Bank

Post by Steve Pomroy »

photofly wrote:Ball just measures the local direction of acceleration - neither slip nor yaw.
That's true, but the measure of lateral acceleration is used as a proxy for slip (despite the fact that it's not always accurate).

<self-promotion class="shameless">
Read about it here: http://www.flightwriter.com/2012/09/step-on-ball.html
</self promotion>
photofly wrote:But what's the advantage of the older (needle) vs the newer (wings) instrument?
I'm with CS on the preference for the T&S, but I think it is really just personal preference, and difficult to justify objectively. As I understand it, the TC is more expensive, and more maintenance-needy. But I've never had to pay maintenance bills, so that's second-hand information.
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Re: Turn Coordinator vs. Turn-and-Bank

Post by iflyforpie »

Look at a Turn and Bank indicator vs a Turn Coordinator on a turbulent flight and you will see why most seasoned pilots prefer the former. The half a dozen TCs I have on my healing shelf vs the one T&B is another reason, related to the first reason.
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Re: Turn Coordinator vs. Turn-and-Bank

Post by CID »

Surfing "plane pr0n" and the best you could come up with was a Cessna Caravan??

Personally, I think the turn coordinator was a reasonable attempt at automation that helped lower time or occasional pilots to interpret what they see on the display. For more serious hardware that is used commercially you tend not to see them installed. It happens but those pilots prefer the turn and bank display.

Of course as you get into heavier iron the thing almost disappears completely except of course for the ball. (And only if you have a third artificial horizon that meets the applicable standard)
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Re: Turn Coordinator vs. Turn-and-Bank

Post by frozen solid »

That's an interesting side-question: larger aircraft do not have a turn&slip indicator or a turn co-ordinator at all. When I first started flying an aircraft that did not have one, I found myself wishing it did. I kind of still do, actually. I wonder why they are almost universally considered redundant on large aircraft, and at the same time considered useful on smaller ones. There is no difference I can perceive between hand-flying a plane over 12,500 pounds in instrument conditions and hand-flying one under 12,500 pounds in instrument conditions. I used to make quite extensive use of the T&B indicator and I still kind of feel like something is missing. People will tell you you don't need it, and that's strictly true, but I still feel like I am flying partial-panel without the damn thing.
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Re: Turn Coordinator vs. Turn-and-Bank

Post by Strega »

The main reason the turn coordinator was created was to remove the "opposite turn" phenomenon from the needle and ball.

The needle and ball uses gyroscopic precession of the gyro rotor to show yaw (and turn) , but when the aircraft (or more precisely the instrument) is rolled quickly, the gyroscopic principle of rigidity in space is applied to the rotor, and the needle will momentarily show a turn in the opposite direction of the roll.. Try it next time you are out flying...
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Re: Turn Coordinator vs. Turn-and-Bank

Post by black hole »

Short Answer: The TC was introduced for pilots that couldn't use the rudder.

BH
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Re: Turn Coordinator vs. Turn-and-Bank

Post by photofly »

Why would poor rudder usage make any difference?
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Re: Turn Coordinator vs. Turn-and-Bank

Post by Chuck Ellsworth »

Why would poor rudder usage make any difference?

That is only a problem when you are unsure of how to understand both or either instruments.
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Re: Turn Coordinator vs. Turn-and-Bank

Post by photofly »

I'm sorry, .; I didn't understand BH's rather cryptic comment, and I don't understand yours either. Can you elaborate, please?
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Chuck Ellsworth
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Re: Turn Coordinator vs. Turn-and-Bank

Post by Chuck Ellsworth »

My comment was made because I can not make any sense out of his statement either.

Actually the conversation about the reserves was much more interesting over on the bush flying forum......but it seems to have vaporized.
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Re: Turn Coordinator vs. Turn-and-Bank

Post by Justjohn »

frozen solid wrote:That's an interesting side-question: larger aircraft do not have a turn&slip indicator or a turn co-ordinator at all. When I first started flying an aircraft that did not have one, I found myself wishing it did. I kind of still do, actually. I wonder why they are almost universally considered redundant on large aircraft, and at the same time considered useful on smaller ones. There is no difference I can perceive between hand-flying a plane over 12,500 pounds in instrument conditions and hand-flying one under 12,500 pounds in instrument conditions. I used to make quite extensive use of the T&B indicator and I still kind of feel like something is missing. People will tell you you don't need it, and that's strictly true, but I still feel like I am flying partial-panel without the damn thing.


You will notice such aircraft have a standby Attitude Indicator instead.
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Re: Turn Coordinator vs. Turn-and-Bank

Post by Chuck Ellsworth »

You will notice such aircraft have a standby Attitude Indicator instead.

There was a time when we had to be able to recover from an unusual attitude using two stage amber so we could not see outside of the airplane using only the turn and bank, the airspeed indicator and the altimeter.

If we could not do that we could not pass the CPL.
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Re: Turn Coordinator vs. Turn-and-Bank

Post by frozen solid »

Justjohn wrote: You will notice such aircraft have a standby Attitude Indicator instead.
I have indeed noticed that, but I'm not talking about redundancy. The turn&slip indicator tells you things that the attitude indicator can only tell you indirectly. I guess I'm just curious about why it's considered necessary enough to pay good money for on small aircraft, some of which also have three A.I.s, but completely unnecessary on larger aircraft.

I AM aware that if you are banked in one direction and the ball is centered, the plane cannot be doing anything other than turning, so in that sense I suppose the instrument is redundant, but I still like it because I learned to fly instruments with one, and it completes the picture for me when I can't see out the window and want some rate-based turning information, in a way that an A.I., or two of them, or three of them, does not. I know you can use basic math to approximate the bank angle necessary for a rate-1 turn, but I like the needle and little "doghouse" better.

Somebody must agree with what I'm trying to say. Don't any of you miss the old turn&bank indicator? I find it comforting because I'm used to it and it's kept me right-side-up in aeroplanes with bad vacuum systems once or twice trying to beat home in terrible weather. I guess I just like it, and feel in the plane I fly now that something is missing. More of a bad feeling than a problem I guess.
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Re: Turn Coordinator vs. Turn-and-Bank

Post by black hole »

I made the statement because with the turn coordinater gives both turn and bank information at the same time. Most modern aircraft are well balanced and very coordinated turns can be made , and recovered from with aileron only and your feet flat on the floor. Now there are a few planes out there like the Beaver which has so much aileron drag that its difficult to fly on a sunny day with aileron only. OK---Now we'll give you the Beaver and a partial panel. Its all about rudder.


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Re: Turn Coordinator vs. Turn-and-Bank

Post by thatlowtimer »

.That's an interesting side-question: larger aircraft do not have a turn&slip indicator or a turn co-ordinator at all. When I first started flying an aircraft that did not have one, I found myself wishing it did. I kind of still do, actually. I wonder why they are almost universally considered redundant on large aircraft, and at the same time considered useful on smaller ones. There is no difference I can perceive between hand-flying a plane over 12,500 pounds in instrument conditions and hand-flying one under 12,500 pounds in instrument conditions. I used to make quite extensive use of the T&B indicator and I still kind of feel like something is missing. People will tell you you don't need it, and that's strictly true, but I still feel like I am flying partial-panel without the damn thing.
Don't those big airplanes still have the "dog house" though?
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Re: Turn Coordinator vs. Turn-and-Bank

Post by x-wind »

If i recall correctly a principle advantage of the turn & bank indicator is the ability to do a informed rate two turn. Not so with a turn coordinator.
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Re: Turn Coordinator vs. Turn-and-Bank

Post by trampbike »

. . wrote:using two stage amber so we could not see outside of the airplane
Little thread drift here: Why is this method not used anymore? It seems much more realistic and efficient than just wearing a hood.
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Re: Turn Coordinator vs. Turn-and-Bank

Post by photofly »

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Re: Turn Coordinator vs. Turn-and-Bank

Post by Chuck Ellsworth »

That is one of the most puzzeling questions in all of aviation.

Someone on this forum once said it was because the amber film you put in the windshield and side windows interfeers with the instructors outside vision.

That is absurd, skiers use amber tinted glasses to see more detail.

Two stage amber is the best method to learn to fly instruments next to flying in cloud.

Personally I think it fell out of use because the instructors were to lazy to put it in and take it out.

For sure wearing a hood is really unorthodox and gives a weird field of vision.
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