Turn Coordinator vs. Turn-and-Bank

[CID]

Just to clarify, a third horizon alone can't be used in lieu of a turn and bank/turn and slip. Here's what the regulation says"

Where the aircraft is equipped with a third attitude indicator that is usable through flight attitudes of 360o of pitch and roll for an aeroplane, or ±80o of pitch and ±120o of roll for a helicopter, the aircraft may be equipped with a slip-skid indicator in lieu of a turn and slip indicator or a turn coordinator.

[CID]

., I heard that the two stage amber was incompatible with some sunglasses. Especially some of the more modern ones.

[x-wind]

CID a question pertaining to those regulations for Night VFR. Are you aware of a definitive guide to determining what is and what is not a stabilized magnetic direction indicator?

http://www.aircraftspruce.ca/menus/in/c ... ision.html ?

"(f) where the aircraft is operated so that an aerodrome is not visible from the aircraft, a stabilized magnetic direction indicator or a gyroscopic direction indicator;"

Regards,

[CID]

x-wind, your question can be answered quite simply. The vertical card compasses offered by PAI are approved under TSO C7c Type 1 "Directional Instrument, Non-Stabilized".

So no, it does not qualify as a stabilized magnetic direction instrument. In my opinion, "stabilized" may as well say "gyro-stabilized" and I think it actually used to say that. they took out the "gyro" because these days there are a few ways to stabilize a compass. Besides the use of a gimbal type gyro, there are strap-down gyros (AHRS) and lasers (so-called "laser-gyros") etc.

I think the original intent was to have a heading indicator that wasn't prone to turning errors while you turn at night and your "visual reference to the surface" may be temporarily blocked.

Definitive answers? That's a tough one. I'm aware of one instance where a pilot was able to convince TC that his PAI vertical card compass met the rule. I completely disagree with that.

The FAA rules for IFR (not night VFR because it's not required) they use the term "Gyroscopic direction indicator (directional gyro or equivalent)."

[photofly]

I have an ignorant question about the two-stage amber; You can't see out of the windows because the light that comes in through the amber filter is blocked by the blue glasses that you wear. But the flight instruments are illuminated by the same amber light that you can't see; so how can you see the instruments?

[x-wind]

Thank you!

[Colonel Sanders]

Vertical card compasses offer incredible bang
for the buck, when it comes to partial panel.

Not only are they more stable than the Airpath
thingies, they look just like a heading indicator -
they aren't laid out opposite like an Airpath, so
it's easier to visualize, and count off the seconds
for the timed turns.

Some airframes can be a b1tch to get them swung
in, though.

[x-wind]

Thanks, I've been considering installing it in the panel vice on the dash but have heard that could be even more problematic for the swing. But, i should be looking at a DG again as I want to fly her at night. Have to figure out if the venturi will support an added instrument to the turn & bank indicator.

It's a Luscombe so Im thinking it'll be a difficult swing regardless.

[Chuck Ellsworth]

I have an ignorant question about the two-stage amber; You can't see out of the windows because the light that comes in through the amber filter is blocked by the blue glasses that you wear. But the flight instruments are illuminated by the same amber light that you can't see; so how can you see the instruments?

Looking through the amber film in the windows everything outside has an amber tint, exactly like wearing amber skiing goggles or amber sunglasses.

With the blue goggles on everything inside the airplane is tinted blue.

When you look up to see out the windshield or side windows the screens look black and you can not see outside.

Very simple and very effective for learning to fly with no outside clues...just like in cloud.

If wearing a hood was normal why don't pilots put a hood on for every IFR flight?

Also wearing a hood screws up your peripheral vision and is like looking at things down a tunnel.

[NeverBlue]

getting back to the original question...

The Turn Coordinator's gyro gimbal is mounted with a 30 degree incline to the longitudinal axis that allows it to sense rotation about the longitudinal and vertical axes. For this reason it can be used to level the wings, thus the different presentation.

The T&B gyro gimbal is mounted at 0 degrees to the longitudinal access and only senses rotation about the vertical axis and cannot be used accurately to level the wings.

They both show slip using an inclinometer. The Turn Coordinator however is a better back-up for the A/H.


...used to fix them on the bench

[photofly]

The Turn Coordinator however is a better back-up for the A/H.

The original question was "why then would you prefer a needle (T&B) rather than a "wings" (TC)?

[Big Pistons Forever]

The advantage of the TC is that is that most modern trainers have most of the adverse yaw effects of power and aileron drag engineered out of them at the speeds produced with low to normal cruise power set. The result is that if you make slow aileron inputs you can treat the TC wings like the horizon bar of the AI which is the strategy most people use on the CPL flight test.

The fact that this is not the correct way to fly this instrument doesn't change the fact that that it works in the artificial flight test environment and flight training is heavily incentivized to prioritize teaching to the test instead of the "best" way to do something.

Personally I totally ignore the TC wings or the T&B needle in VFR flight. For IFR flight the only thing I want to know is "am I holding a rate one turn". I find the T&B needle much more useful for this and that is IMO, the reason you will never see a TC in any airplane bigger then a light piston twin.

As for the whole "view limiting device" debate, my personal opinion is that the advent of the new generation sims like the RedBird now mean that the best place to teach instrument flying is in the sim.

The main advantage of the airplane is the fact that you can experience "real" IMC conditions knowing that you can't just hit the pause button if things go bad and you get to experience all of the physical forces of flight acting on your body and senses while flying by reference to the instruments, something that GA sims can't do all that well.

Flying IFR in VFR conditions greatly reduces the value of the aircraft training and so you should IMO plan your training to get as much actual cloud time as possible. When I did my MEIFR I waited until December and deliberately scheduled my trips on bad weather days. The result was that 8.0 hrs of my 9.9 hours of IFR training was in actual IMC and included an actual minimums ILS and a actual missed approach off a night circling approach.

[NeverBlue]

The original question was "why then would you prefer a needle (T&B) rather than a "wings" (TC)?

the TC, because...

it can be used to level the wings

testy, testy photofly!

[photofly]

The original question was "why then would you prefer a needle (T&B) rather than a "wings" (TC)?

the TC, because...

it can be used to level the wings

testy, testy photofly!

I think the point has got lost somewhere in the journey. (No, I'm not being testy.) I know why you might prefer "wings" rather than "needle", because it's easier to keep the wings level. The question wasn't which would you prefer. The photo of the caravan shows that whoever specified that panel preferred "needle" over "wings". Why?

Wings: easier to use for partial panel
Needle: easier to maintain a standard rate turn in rough air

Anything else?

[Beefitarian]

Isn't it more of an aid to help VFR pilots. I was told to learn how to time a 180 degree turn with it in case I inadvertently entered cloud. Then I could be accurately going the opposite direction if my DG has quit or is just beat from doing spins and suffers precessional errors doing a 180.

Your fancy 747 has a bunch of upgrades so no DG or turn and bank.

Of course that was before GPS went civilian and I have not practiced so I can't remember if it takes 2 minutes to turn around still.

., I heard that the two stage amber was incompatible with some sunglasses. Especially some of the more modern ones.

Any chance it made the already difficult to see red light from the tower signal gun near impossible to see? Followed by a fear monger/transport employee...

[NeverBlue]

I think the point has got lost somewhere in the journey.

perhaps you are right...

[Strega]

Anything else?

Read my earlier reply..

[photofly]

Anything else?

Read my earlier reply..

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...

I can't try it next time I'm flying as everything I have available has "wings" and not a "needle".

Where does this "opposite turn" tendency arise from? Can you be more detailed than simply "the gyroscopic principle of rigidity in space is applied to the rotor" please?

EDIT: oh, you mean because the single gimbal allows motion in roll, so a roll to the left leaves the gyro axis unchanged in space, indicating a turn the right. OK.

[Strega]

The needle and ball shows a turn from the gyro inside precessing the "yaw force" applied, when you roll quickly, the gyro for a brief moment, exhibits its "rigidity in space" and actually will deflect in the opposite direction of the roll.

I dont have a cross section available at the moment, but read up on the operation principles of each, and you will understand the opposite turn phenomenon.

[photofly]

I see what you mean, now.

[Strega]

Keep in mind if you roll gently into, and out of a turn, the opposite turn bit is not an issue...
Another reason not to fly ham-fisted.