Jabiru - Gyroscope

[anjum_jabiru]

Hi Guys. It's me again. Please excuse me if this sounds dumb. On the Jabiru panel that I hire there is a switch for the Gyros, which when switched on makes a whirring sound. The turn co-ordinator and compass works quite well even when this gyro switch is off. I am unable to understand the purpose of these switches as there is virtually no effect on the turn co-ordinator or compass except for the fact that there is no whirring sound.

 

Please could someone enlighten me as to the purpose of this switch and should I turn it on during flight? I would like to keep all electrical switches off if not really required to minimise the risk of any fire hazard in flight.

 

Thanks

 

 

[frank marriott]

Have you read the POH?

 

 

[kgwilson]

As far as I'm aware the turn coordinator in a Jab is electric & the compass is self contained & only needs the earths magnetic field to work. The gyro would be required for an A/H but Jabs don't have them. Maybe it is a left over when someone changed instruments

 

 

[anjum_jabiru]

If that switch is meant for the turn co-ordinator then turning it on or off has no effect on the turn co-ordinator, except for the whirring sound. I have flown it with the switch in the on as well as the off positions and the turn co-cordinator works alright both ways. There is no other separate electric switch for the turn co-ordinator. The POH says nothing about it.

 

 

[Piet Fil]

Anjum,

 

The short answer is the switch needs to be on for it to work correctly.

 

A quick search of the Internet yields the following

 

The turn indicator is a gyroscopic instrument that works on the principle of precession. The gyro is mounted in a gimbal. The gyro's rotational axis is in-line with the lateral (pitch) axis of the aircraft, while the gimbal has limited freedom around the longitudinal (roll) axis of the aircraft.

 

As the aircraft yaws, a torque force is applied to the gyro around the vertical axis, due to aircraft yaw, which causes gyro precession around the roll axis. The gyro spins on an axis that is 90 degrees relative to the direction of the applied yaw torque force. The gyro and gimbal rotate (around the roll axis) with limited freedom against a calibrated spring. The torque force against the spring reaches an equilibrium and the angle that the gimbal and gyro become positioned is directly connected to the display needle, thereby indicating the rate of turn.[3] In the turn coordinator, the gyro is canted 30 degrees from the horizontal so it responds to roll as well as yaw.

 

Phil

 

 

[planesmaker]

Perhaps you have an electric AH? And vacuum turn coordinator? Best to ask someone close by to look at your aircraft and tell you what is what. Whirring sound is a gyro spinning, no spinny=no worky

 

 

[Oscar]

If that switch is meant for the turn co-ordinator then turning it on or off has no effect on the turn co-ordinator, except for the whirring sound. I have flown it with the switch in the on as well as the off positions and the turn co-cordinator works alright both ways. There is no other separate electric switch for the turn co-ordinator. The POH says nothing about it.

FFS - if the Turn Co-ordinator OR Turn and Slip Indicator ('ball and bat') is electric, then it needs electric power to spin the gyro. If it's vacuum - (BOTH types come in either vacuum OR electric ), then electric power to the instrument would only need to be applied to power the instrument backlight for night flying. A Turn Co-ordinator is a subtly different instrument to a T&S instrument; for general flying in VFR particularly, a Turn Co-ordinator is probably the more useful - but for full VFR, a T&S plus an A/H, is the best combination - provided you are trained to know what they are reporting.

 

The 'whirring sound' is the gyro spinning up. Without the gyro spinning, the instrument is useless, and gives entirely false information. Without whatever power is required, the very sophisticated 'correction' facilities of either, are NOT present on the display, and if needing to rely on that information, you will be in deep sh$t.

 

Please- for your own safety - research the operating principles of both instruments. They ARE different; even the axis of the gyro is different. And, either needs to have the appropriate source of energy in operation.

 

 

[billwoodmason]

It will be for the turn coordinator the whirring sound is the gyro inside the instrument. You can tell when you switch it on there is an orange flag indicator on the dial. When it is switched off you can't see it.

 

Cheers.

 

 

[facthunter]

They spin for quite a while after you have shut down everything. Many Gyro instruments are caged when not used to protect the gimbals (or if you are doing aeros) They are expensive to buy and maintain and outdated. I think gyros are done digitally these days. An ion beam being deflected. Nev

 

 

[jakej]

&... if it's Chinese manufacture then anything could be going on, don't know why they are allowed to be used here.

 

 

[anjum_jabiru]

My understanding is that the switch is for gyro and to make the turn coordinator work. The confusion is that why does the turn coordinator work with the gyro / electric switch off? It should not move. But it does move correctly in the turn! May be it is electric as well as vacuum.

 

 

[bexrbetter]

Have you read the POH?

Girl.

 

 

[frank marriott]

Girl.

?

 

 

[jetboy]

If you have switched on an electric powered gyro instrument then it will still appear to be working for a period of time after its switched off.

 

That may be the reason you think its working without the switch.

 

 

[anjum_jabiru]

No even with the switch off it works during the entire flight of 1 hr, well after the whirring stops.

 

Bexrbetter - Yes I hv read the POH.

 

 

[frank marriott]

Just to be clear, are you talking about BOTH the rate of turn indicator and the slip indicator working i.e not just the slip indicator.

 

 

[anjum_jabiru]

Now that you mention it, I am sure of the ball moving (slip indicator) but can not recollect the miniature white aeroplane (turn indicator) moving or not. I think you may have nailed it. It must be the ball that moves but not turn indicator. I will check it the next time I take it up and let you know.

 

 

[billwoodmason]

You will find they both move without power - the gyro stabilises the instrument for a more reliable and accurate reading of the turn indicator when turned on. It has no effect on the slip ball.

 

 

[anjum_jabiru]

Thanks. This sums it up :)

 

 

[bexrbetter]

?

Real men don't read manuals!

 

 

[anjum_jabiru]

... And die young leaving their women behind to have fun with other real men

 

 

[Blueadventures]

My understanding is that the switch is for gyro and to make the turn coordinator work. The confusion is that why does the turn coordinator work with the gyro / electric switch off? It should not move. But it does move correctly in the turn! May be it is electric as well as vacuum.

Maybe its wired to the general instrument or another switch. Try waiting a short time after closing the master switch and then turn on your other switches and note when the whiring starts. Cheers

Mike

 

 

[anjum_jabiru]

It is definitely for the gyro as I can only hear the whirring when switched on, which stops after a few seconds once all switches are off. I think it is for the turn indicator / to improve accuracy of the slip and turn coordinator.

 

 

[Russ]

All this " might be this...might be that ".... just maybe, a call to jab could reveal the answer. I've found every single time I've dealt with them, it's been a good experience.

 

 

[jetjr]

These electric T&B use a lot of power, theres an isolator switch in case of problems or to stop power use before take off when Jab altenators dont do much.