Fail safe stby attitude indication?

[cliffy]

Just thinking. Why not go to a vacuum AI connected to a standard old school venturi then,

if you're flyin' you've got attitude! No mechanical pumps to worry about or electrical issues!

Of course it won't erect until you're airborne but

I flew many IFR flights in my younger days with that setup in my C140. 

[1964-M20E]

Don't know Cliffy sounds like you're trying to join the mile high club

 

back to topic how much drag does a venturi cause?  how much speed would you loose?

 

I've though of this as well even a retractable unit for backup.

 

However, today everything is going redundant electronic and battery backup and if the FAA would get out of the cockpit for part 93 ops we could have many helpful things for situational awareness and safety at a fraction of the cost today.

 

 

 

 

[ryoder]

The FAA "We're not happy unless you're not happy."

Edited October 2, 2015 by ryoder

[cliffy]

My problem with all the backup batteries is their capacity after a couple of years.

I don't know of any capacity test requirements for them for CAW. Does anyone have any info on that? 

Most batteries lose capacity after time. Ever had a laptop battery last 5 years? 

[1964-M20E]

I'm sure the manufacturer has some type of test procedure to do an annual.  However, during your annual turn on the devices let them stabilize and then turn off the master switch and let them continue running to see how long they will run.  Simple but effective then allow them to recharge after the test.

 

 

[N201MKTurbo]

The problem with a venturi is it ices up. this is the main reason they stopped using them.

Now a retractable RAT hooked to an electric AI would be the bomb. I guess a RAT could ice up too.

https://en.wikipedia.org/wiki/Ram_air_turbine

 

 

[carusoam]

Slight difference with the Venturi ice...

The Venturi has an additional risk of icing, similar to carb ice.  The Venturi generates a low pressure area and thus causes a thermodynamicly induced low temperature area as well.  For ice, just add moisture.

Neither system will do well in an ordinary icing environment without heat similar to a pitot heat system.

Thermodynamics for pilots,

-a-

[Guest]

Just thinking. Why not go to a vacuum AI connected to a standard old school venturi then,

if you're flyin' you've got attitude! No mechanical pumps to worry about or electrical issues!

Of course it won't erect until you're airborne but

I flew many IFR flights in my younger days with that setup in my C140. 

I've often thought that if you placed the Venturi in the cowl flap exit air path it would never ice over.

Clarence

[M20F]

I I personally like the idea of having both vacuum and electric.  While I prefer electric if for whatever reason the main bus fried everything electrical having a couple vacuum gauges is reassuring. 

[Andy95W]

I I personally like the idea of having both vacuum and electric.  While I prefer electric if for whatever reason the main bus fried everything electrical having a couple vacuum gauges is reassuring. 

Exactly why I have an STEC autopilot that uses the electric turn coordinator for attitude information.  If I lose vacuum, I can engage the wing-leveler portion of the autopilot.  If I lose electric, I can hand fly with the AI and DG.