Stark 1, 2, 3 method and Turn and Bank indicators.

[stratobee]

Help me clarify something.

My new plane has a Turn and Bank indicator and not a Turn Coordinator that I'm used to. I thought about replacing it eventually, but then have read that it's actually in many ways a better instrument to recover on. I'm a little fuzzy on how to recover on that instrument and what I've read about Howard Starks age old 1, 2, 3 method doesn't seem to compute. It says:

1. Stop the turn (with rudder pressure based on the turn needle indication)
2. Level the wings (by centering the slip/skid ball with the turn stopped)
3. Control the airspeed (with careful application of elevator based on the airspeed indicator's trend)

I can see how there's no way of leveling the wings on the ball, but doesn't the turn needle provide that the wing level info, and the ball the turn? Or am I confused? Here it seems to be the other way around.

 

[MauleSkinner]

The needle in a T&B is a pure yaw instrument...the axis of gyro rotation is fore-and-aft in the instrument, so it shows nothing in roll. It's mounted such that it can't move based on pitch changes. It stands to reason, then, that the needle is centered with rudder, step 1.

If the needle is centered, the airplane isn't turning. If the airplane isn't turning, there's no centrifugal/centripetal force acting on the ball, so it acts just like a bubble level, and will tell you when the wings are level. Obviously the wings are leveled with aileron, so that's step 2.

The difference between a turn coordinator and a T&B is that the TC was invented to drive an autopilot...the axis of gyro rotation has a 30-degree or so incline, so the front end is higher than the back (or vice-versa). Now it indicates changes in yaw, bank, or some combination thereof. But pay attention to the note on the face...it still doesn't provide bank information, just possible indications of CHANGE in bank. But since the yaw information is "corrupted" by bank change information, it then, as you read, makes the TC less precise as the primary instrument for upset recovery.

 

[stratobee]

Thanks Maule. Great and clear explanation!

Surprised this wasn't covered more during my IFR training. You'd think it could potentially be pretty handy to know if you find yourself in a spin in IMC to know that: with a TC you can't recover, but with a TB you can. The ball on it's own won't tell you.

 

[flyingron]

The difference between a turn coordinator and a T&B is that the TC was invented to drive an autopilot...

That's not quite true. The idea of the canted rate gyro was invented for the autopilot. The turn coordinator was designed to use the same idea because someone felt it was going to be a better idea for partial panel work than an upright needle ball. TC's were around for a long time before people started connecting them to the autopilot (or in some cases, building the autopilot inside them).

Of course, there is some discussion as to whether the TC helps or hinders partial panel work.

 

[MauleSkinner]

Thanks Maule. Great and clear explanation!

Surprised this wasn't covered more during my IFR training. You'd think it could potentially be pretty handy to know if you find yourself in a spin in IMC to know that: with a TC you can't recover, but with a TB you can. The ball on it's own won't tell you.

You probably can do a spin recovery with a TC, it just doesn't isolate yaw indication the way a T&B does.

Quite honestly, if you find yourself in a spin in IMC, you're probably so far behind the airplane already that it'd be a moot point.

 

[SbestCFII]

You can use the TC for spin recovery in IMC, since the TC shows the direction of the spin...rudder opposite the spin. Best to avoid special disorientation and not spin in the first place. Scan, scan, scan.