A couple of recent threads on panel retrofits and new whizbang flight instruments has me wondering about the old stand-by's. Although the turn coordinator and the turn-and-bank seem pretty similar, I recall reading years ago that there's actually a pretty big difference in the way they work. The turn coordinator's airplane-wing style presentation seems more intuitive, but I kinda remember that the turn-and-bank was actually more useful for partial-panel instrument flying- as in "needle / ball / airspeed". Anyone care to school me on this?

The turn and bank gyro is set up to only indicate a left or right turn.
The turn coordinator is set up with the gyro canted so it will indicate left or right turn but also left or right bank.

Turn coordinator is better for me with partial panel situations!

Personally, I like that big old needle pointing at the dog house when I'm making my turns.

Real life, whatever you practice with, and use, will keep the shiny side up.

Gump

I do not like either! A backup attitude indicator makes more sense;

Timed turns and rate of turn (degrees per second) are theoretically useful to pilots and ATC.

If only bank angle and airspeed are available:

bank angle = (TASkts / 10) + 5

Scout on amphibs using an electric attitude indicator I use this

15 degrees of bank = 100kts / 10 + 5 = (3) degree per second turn

Example:

ICAO wrote:For aircraft holding purposes, ICAO mandates that all turns should be made, "at a bank angle of 25° or at a rate of 3° per second, whichever requires the lesser bank."[4] By the above formula, a rate one turn at a TAS greater than 180 knots would require a bank angle of more than 25 degrees. Therefore faster aircraft just use 25 degrees for their turns.

https://en.m.wikipedia.org/wiki/Standard_rate_turn

I liked the needle better because with DG or RMI failed, you could still use dynamic proactive rudder or anti-torque pedal to keep the needle centered. The little airplane, like the AH, has to be off more before you notice it. Somewhere on an Army annual written, I remember that DG or RMI was primary for wings/tip path plane level and that Turn and Bank needle became primary when DG failed even with AH working.

I like the turn coordinator for instrument flying, but In a real world vacuum failure, I don't think it would matter which you had to look at so long as you have something to prevent over banking. Either would be a supporting instrument to the compass and altimeter while you got vectors. As mentioned, a backup AI would be my preference too.

I'm confused, how does either instrument help you in a vacuum failure situation? Aren't they vacuum instruments?

whee wrote:I'm confused, how does either instrument help you in a vacuum failure situation? Aren't they vacuum instruments?

No, the Turn coordinator or turn-and-bank are electrically powered gyros.

No, electric.

Gump

Ok, thanks for setting me straight. In defense of my ignorance, the T&B I had in the Luscombe was vacuum.

Turn coordinator is electric...but I did not realize there were electric t&b instruments...mine is vacuum...

Yes, some old turn and banks are vacuum. The only times I have seen this is with the old venturi system.

I have never seen a vac turn coordinator.
But maybe they exist?

8GCBC wrote: I do not like either! A backup attitude indicator makes more sense.........

Not too worried about making perfect 2-minute turns, so an attitude indicator makes more sense to me also. An AI (aka artificial horizon) gives both pitch & bank info, whereas with a T&B or TC you need to watch the airspeed to make sure the pitch doesn't get away from you. Hence the expression "needle ball airspeed". Needle and ball centered, ASI on speed = level flight.

Both instruments indicate rate of turn, but because of the canted gyro in the turn coordinator, it is able to indicate rate of roll as you enter a turn.

hotrod180 wrote:

8GCBC wrote: I do not like either! A backup attitude indicator makes more sense.........

Not too worried about making perfect 2-minute turns, so an attitude indicator makes more sense to me also. An AI (aka artificial horizon) gives both pitch & bank info, whereas with a T&B or TC you need to watch the airspeed to make sure the pitch doesn't get away from you. Hence the expression "needle ball airspeed". Needle and ball centered, ASI on speed = level flight.

My backup AH (electric) also comes with a inclinometer (ball). Much better than a turn bank instrument.

The speed of my aircraft is so slow making (3) degree/second turns is easy.

8GCBC wrote: My backup AH (electric) also comes with a inclinometer (ball). Much better than a turn bank instrument.....

Yes, I agree. here's what I'd like to have, but there's about 2600 reasons why I don't.

hotrod180 wrote:

8GCBC wrote: My backup AH (electric) also comes with a inclinometer (ball). Much better than a turn bank instrument.....

Yes, I agree. here's what I'd like to have, but there's about 2600 reasons why I don't.

Better is sometimes more dinero! I like it too

8GCBC wrote:

hotrod180 wrote:

8GCBC wrote: My backup AH (electric) also comes with a inclinometer (ball). Much better than a turn bank instrument.....

Yes, I agree. here's what I'd like to have, but there's about 2600 reasons why I don't.

Better is sometimes more dinero! I like it too

Won't the Dynon D2 do the same thing for you at 1/3 the price?
Charles

Yes. But Hammer's recent remark about trusting your ass to a device that plugs into the cigar-lighter gave me second thoughts-- although I am way more likely to buy the Dynon D2 for a grand than this RC Allen 2600 for $2600. (hey, I just figured out how they came up with the model number....)

I think how it is engineered is more important than how it gets its power. However, I'd have a hard time trusting my life to a portable instrument unless I had lots of time behind it and knew it was 100% accurate all the time. I bet the D2 is very accurate because it is a purpose designed device; it's not like those AH apps for your tablet.