Bank indicator

[Pink Panther]

Hello,

Could someone tell me where the turn & bank indicator are located in a modern glass cockpit?

Thanks and have a safe flight!

Reinier

 

[Typhoon1244]

Since jet's don't generally make standard rate turns, a traditional turn and bank indicator is unnecessary. (Making a two-minute three-sixty in a 747, for example, would require a bank angle and G-loading that would impress the heck out of you!)

On the CRJ-200 the inclinometer (or "ball"*) is incorporated into the sky pointer in the artificial horizon portion of the EADI. There's another one in the base of the standby horizon in the middle of the instrument panel.



*On our electronic displays, the "ball" is actually a rectangle that sits flush with the base of the sky pointer when in coordinated flight. Ergo, it's called the "brick."

 

[cessna_driver2]

Aren't jets typically 1/2 standard rate turns?

 

[Pink Panther]

Thanks,

But if jet's don't make standard rate turns, what kind of turns do they make, and how can a pilot see whether he is flying a coordinated turn?

Furthermore, if the inclinometer is incorporated in the sky pointer, how can you see whether you are flying a coordinated turn?

best wishes,

 

[Typhoon1244]

...if jet's don't make standard rate turns, what kind of turns do they make...?

In most large jetliners, turns are limited to thirty degrees of bank. That's about as far as you can go without making the passengers uncomfortable and unnecessarily stressing the airframe. The flight director/autopilot limits itself to twenty-five degrees, and can be reduced to 12.5 degrees.

Remember, the bank angle required to make a standard-rate turn increases with airspeed.* If you're in a Cherokee at 80 knots, it's a nice comfortable bank angle. Now imagine a Tri-Star at 480 knots...!

...how can a pilot see whether he is flying a coordinated turn?

The "brick" works exactly like the "ball" in your turn coordinator or turn-and-bank indicator. Assuming you're not inverted, it's easily in your scan. In fact, having it incorporated into the sky pointer makes your scan a lot easier...your eyes only have to travel a fraction of a degree to rapidly scan the bank angle and the "brick."



*Does anybody remember that formula?

 

[avbug]

While there is an indication of quality of turn, it's typically a nice-to-know function (and has bearing only during an assymetrcal thrust situation, such as an engine shutdown). Normal flight in most turbojets consists of keeping the feet on the floor, or letting them sleep on the rudder pedals. The rudder is seldom touched, except for taxi in aircraft not using a tiller.

"Coordination" is nearly, or completely, automatic. Additionally, adverse yaw in most turbojet airplanes is nearly nonexistant with respect to required pilot input. This means that the pilot doesn't have much need of rudder use in normal operations, and consequently not much need to look at instrumentation to "coordinate" anything.

 

[rgnlwannabe]

I think you are talking about the formula for a standard rate turn at different airspeeds, and it is just 15% of your airspeed. So in a Cherokee doing 100 knots, it is 15 degrees of bank. In a larger airplane doing 300 knots, it is 45 degrees of bank.

 

[onthebeach]

Rate of Turn formulas

Here are a couple to use.
----------------------------------------
To calculate ROT for a given bank angle:

ROT = (1091 x tangent of bank angle) / TAS

Example: 25 degree bank angle & 450 KTAS:

ROT = (1091 x 0.466) / 450 = 1.1 deg per sec
-------------------------------------------
To calculate angle of bank for a given turn rate:

bank angle = arctan [(TAS x deg per sec) / 1091)]

Example: bank angle required to turn 3 deg per sec @ 450 KTAS:

bank angle = arctan [(450 x 3) / 1091)] = 51 degrees.
-----------------------------------------------------
You can see why high speed aircraft turn much less than standard rate.

The various rules-of-thumb for SRT bank angles (i.e., "10% of airspeed, plus 7," etc.) are only accurate in a small speed range, because the equations are non-linear due to the trigonometric functions involved.

The best reference I know on this subject is *Aerodynamics for Naval Aviators* (really, it's not *just* for NA's).

 

[Typhoon1244]

Re: Rate of Turn formulas

The best reference I know on this subject is Aerodynamics for Naval Aviators.

It's been gathering dust since I got hired.

(Maybe I need to dig that thing out...)

 

[TonyC]

Turn & SLIP

Could someone tell me where the turn & bank indicator are located in a modern glass cockpit?

I do believe it's actually referred to as a Turn and SLIP Indicator. One portion indicates the angle of bank. The other portion indicates the amount of sideslip (or skid) being induced, or, in other words, how COORDINATED the turn is. (Neither portion directly dispays RATE of turn.)

The Honeywell "glass" on the MD-11/10 incorporates a slip indicator into the "Sky pointer" which obviously displays the bank angle. While it appears at first glance to be a simple triangle pointing to the angle of bank (straight up for level flight), it is in fact a triangle sitting atop a trapezoid. When the turn is uncoordinated, the trapezoid displaces laterally from the triangle in much the same way a ball would displace in the fluid-filled tube on conventional instruments. ("Step on the ball" is replaced by "step on the trapezoid.")

 

[groundpointsix]

Re: Turn & SLIP

I do believe it's actually referred to as a Turn and SLIP Indicator. One portion indicates the angle of bank. The other portion indicates the amount of sideslip (or skid) being induced, or, in other words, how COORDINATED the turn is. (Neither portion directly dispays RATE of turn.)

Incorrect.

The Turn and Slip indicator (or turn coordinator, depending on what you have installed) only shows RATE of turn. If you keep the ball centered, you can use the turn coordinator or turn and slip indicator to tell you that you are, in fact, banked, but the actual angle of bank is only an indirect indication.

Think of it this way. You are in straight and level flight, you step on the rudder. The ball is going to go out to the side and the miniature airplane is going to indicate a turn, but you're still level. (Same principle applies if you're taxiing on the ground). So in conclusion, it can indicate the angle of bank, but you're not going to just be able to look at the turn coordinator to know how steep a turn you're in.

 

[GREAT LAKES]

Ball

Since jet's don't generally make standard rate turns, a traditional turn and bank indicator is unnecessary. (Making a two-minute three-sixty in a 747, for example, would require a bank angle and G-loading that would impress the heck out of you!)

On the CRJ-200 the inclinometer (or "ball"*) is incorporated into the sky pointer in the artificial horizon portion of the EADI. There's another one in the base of the standby horizon in the middle of the instrument panel.



*On our electronic displays, the "ball" is actually a rectangle that sits flush with the base of the sky pointer when in coordinated flight. Ergo, it's called the "brick."

Or the "Doghouse"

 

[Typhoon1244]

Re: Ball

Or the "Doghouse"

Po-tay-to, po-tah-to.

 

[Pink Panther]

Quote:
While there is an indication of quality of turn, it's typically a nice-to-know function (and has bearing only during an assymetrcal thrust situation, such as an engine shutdown). Normal flight in most turbojets consists of keeping the feet on the floor, or letting them sleep on the rudder pedals. The rudder is seldom touched, except for taxi in aircraft not using a tiller.

"Coordination" is nearly, or completely, automatic. Additionally, adverse yaw in most turbojet airplanes is nearly nonexistant with respect to required pilot input. This means that the pilot doesn't have much need of rudder use in normal operations, and consequently not much need to look at instrumentation to "coordinate" anything.
end of quote.


Could someone tell me which instrument or device indicates the quality of turn? For the second part of Avbug's answer, may I conclude that the rudder is linked to the aileron input. That means that if the pilot makes a turn, that the rudder automaticaly deflects without a touch on the pedals.

 

[njcapt]

Could someone tell me which instrument or device indicates the quality of turn? For the second part of Avbug's answer, may I conclude that the rudder is linked to the aileron input. That means that if the pilot makes a turn, that the rudder automaticaly deflects without a touch on the pedals.

Weeelllll, not really. Most large jets have roll spoilers that raise on the wing opposite the one that has the downward deflected aileron in a bank. This opposes the adverse yaw caused by a DD aileron creating more lift on a given wing (and kills some lift on the UD aileron's wing, assisting in roll force) . Therefore, most turns are already fairly coordinated.

While flying around on a single engine, however, whole butt-loads (and varying amounts) of rudder trim are needed to remain in coordinated flight. Adding or reducing power creates the largest requirement for changing rudder trim, but configuration and attitude changes create a need for trim inputs. Then you use the brick just like the ball on a turn coordinator (or doghouse for those of you not weaned off of Cessna equipment). Step on the ball (or brick) to coordinate the aircraft.

Trivia: Roll spoilers really have a great effect on the amount of roll force generated. I remember having the instructor disable the roll spoilers in a Dash-8 sim session (the Dash being one aircraft that had roll spoilers and manually actuated ailerons). The authority without the spoilers was very limited and provided extermely slow response.

 

[Brett Hull]

FAR

The boss tried giving me a "pop-quiz" while climbing out a couple of months ago. He asked me why we don't have a turn-and-bank indicator in the learjet. I told him pretty much what Typhoon said. He said 'bull$hit and tried telling me that it's because the flight director always gives you a standard rate. So I asked him why the FD always goes to 25 degrees no matter how fast we're going. He told me to find out and get back to him.

Anyone know the FAR or section in the AIM that says you don't have to have the turn and bank indicator? I remember reading it a long time ago, but I can't seem to find it. Is it in part 25?

Edited 'cause I found the answer in 25.1303 (about 5 minutes after asking the question) . I'll leave it here for the humor, though.

 

[Singlecoil]

Re: FAR

The boss tried giving me a "pop-quiz" while climbing out a couple of months ago. He asked me why we don't have a turn-and-bank indicator in the learjet. I told him pretty much what Typhoon said. He said 'bull$hit and tried telling me that it's because the flight director always gives you a standard rate. So I asked him why the FD always goes to 25 degrees no matter how fast we're going. He told me to find out and get back to him.

Sounds like your boss is a bit of a moron.

Incidentally, the MD-80 requires a fair amount of rudder to keep turns coordinated which was a surprise for me. It might have something to do with how much that design has been stretched over the years.

 

[100LL... Again!]

Standard rate:

15% is a rough approximation for light aircraft speeds, but it does not work well for much higher speeds.


Flight directors:[B/]

Most flight directors go to a fixed bank of around 25-28 (or so) degrees. No flight director I know of has any correlation to standard rate, although many people think so.

This yields a standard rate turn if your TAS is approximately 180-ish (I'll do the math later).

Therefore, if using the flight director, you will be sufficiently close to standard rate in most environments where any serious vectoring is taking place. Faster than that speed = a little less than std rate.

What if you are much faster? ATC willtake this into account, since they pretty much rely on experience rather than a theoretical "standard rate" turn to know what a fast turbine aircraft is going to do.

I'll bet that it is the general aviation folks that provide the most surprises in terms of not turning in an expected manner.
Juuust kidding.


The Ball:

Becomes somewhat less critical in large aircraft due to the yaw damper. If you tried to coordinate manually, you would likely make the guy in the last row puke. You can do it, but nowhere near as good as the damper.

For engine-out ops: The ball can be used, but in reality you really don't need it. Using the ball is one technique, but the ball makes a crappy control instrument. Especially in simulators.

I can cover up the ball and a good pilot won't even miss a beat.
Perfect engine-out procedures every time.

Before I get into a war with Avbug over this, perhaps there is some use for it in the fire-type he is doing.

Why is the ball a bad control instrument? It reacts to more factors than just the asymmetric power or thrust. It overswings if the pilot overcontrolls, it is subject to effects from turbulence as well.

You can use the ball, but you do not need it.

As a matter of fact, you can get to the point where you don't need to look at the ball much in any airplane, ever.

 

[njcapt]

Re: Re: FAR

Sounds like your boss is a bit of a moron.

Incidentally, the MD-80 requires a fair amount of rudder to keep turns coordinated which was a surprise for me. It might have something to do with how much that design has been stretched over the years.

I'll second the moron assessment. The big tool wants to show off how smart he is by asking some totally non-pertinent question.

I basically relearned how to use the rudder when I got typed in the MD-80. I don't know whether the roll spoilers are undersized or if it's related to how close the wings and tail are located together versus the length of the aircraft (limited arm between the control surface and the center of pressure or some other aerodynamic shlt). You could nail a roll out on a heading and the nose would swing back five degrees or so as you reached wings level. It got so I would stay in the bank until I got to the heading and use rudder during the roll out to keep the nose on heading. Stayed coordinated and worked like a charm.

 

[Brett Hull]

Re: Re: Re: FAR

I'll second the moron assessment. The big tool wants to show off how smart he is by asking some totally non-pertinent question.

You should see our 'sweet' new panel he just had installed. 2 Garmin 430's and a MX 20 MFD. It looks Bonanzariffic! Nicest Lear 35 in the world as he says.