Electronic AI

[jlfernan]

I'm starting to plan my panel and while I don't want to go full electronic(meaning an EFIS of MFD) I want reliable. TruTrak has an electronic AI that looks interesting and goes for about a grand. I figure for the cost of a non-TSO AI and a vacuum pump I can get the truTrak and not have to worry about a pump failure or having to replace it at 500 hours. The problem is I don't really understand TruTrak's terminology. Below is the description as written is a certain catalog:

TruTrak Solid State ADI (Attitude Direction Indicator).
**Bank Angle - Instantaneous Gryo Data
**Pitch - Gyro Enhanced Vertical Speed
**Direction - Electronic DG Showing Track
(Internal Lighting Standard)

I don't get "Pitch - Gyro Enhanced Vertical Speed". What's the difference between this and a vacuum powered AI? Also, is anyone out there flying with one of these yet or seen one in action that can compare it to traditional AI?

[Wicked Stick]

I could be wrong, but here's my take on it.

The bank is like it says, and acts like a turn co-ordinator.
The pitch however, sort of acts like a "trend" indicator. By that I mean to say it reacts kind of like the VSI does for the altitude.
The direction is pretty much like a digital compass.

Not sure if this helps to explain it, and also take this with a grain of salt since I have yet to fly behind one, but do plan to put the ADI Pilot II in my panel and use it for a 2 axis autopilot driven RV-8.

[svanarts]

From the description it sounds like a sort of graphical "instantaneous VSI".

[Wicked Stick]

At OSH I got to see a video clip of an in-flight test.
They installed it where the turn co-ordinator would normaly be in a standard six pack so you could compare it to the Horizon Indicator during the flight.

Not sure if they have a video online somewhere, but you might want to search or ask them if they have such a video available online.

[svanarts]

If you find a video, let me know, I'd like to see it. I can't quite picture how the thing works. There are a couple of guys who's opinion I respect that have one and they really like it. I think I'll just go for glass.

[jlfernan]

I think I figured out at least the pitch part. It works like a VSI. If you are climbing, the AI will show you nose up, if you are descending, the opposite. Where it's different from a traditional AI would be like in slow flight. You may have your nose pitched up, but as long as you fly level, Trutrak's AI will show nose level. I think I'll go with Falcon's electric AI. I'll still have electric reliability and it works like a standard AI. Phew!

[mustang]

Yes,
I have a friend with one of these and he has mega hours of experience. In my opinion, only someone with a LOT of experience should use this instrument.

Here is a "for instance" where you could be easily misled. Lets say you were IMC and practicing slow flight. With this instrument you could be 20 degrees nose up, but descending with just a trickle of power on, but this instrument would show that you were slightly nose down?!?!?!

The pitch attitude is gyro enhanced rate of climb/descent. This is not nearly a true pitch attitude. Not even close. Think about it!

Lets say that you were at 20 degrees nose up and staying level at your chosen altitude with power. This instrument would show that you were nose level. I would rather have a vacuum operated gyro horizon than this thing. Better yet, an electric attitude instrument would be the best back-up.

Cheers, Pete

[4kilo]

Lets say you were IMC and practicing slow flight.

OK, enlighten me on why anyone would be doing this.

By the way, any normal airfoil will stall at very nearly 15 degrees alpha, so you would need a really strange angle of incidence or an unusual aircraft configuration to maintain level flight with a 20 degree deck angle.

Pat

[Spike]

OK, enlighten me on why anyone would be doing this.

Because any instructor may ask you to. Speed restrictions during an IFR flight are quite allowable.


- Spike

[captain_john]

Spike, I am with you on this one.

Pat, I can see your perspective.

How is that for playing both sides of the fence!



Spike, the slower you fly, the less airspace you move through.

Pat, Speed is life, Altitude is life insurance!



Fly the plane as best as you can with what you have available!

CJ

[captain_john]

OH!

WS and Mustang... yah, that is the way I see it too.

The ADI is a blend of the 2 instruments, VSI and Turn Coordinator. It uses those criteria to visualize the horizon. Given the limitations, it does a fine job.

...with a grain of salt.

CJ

[4kilo]

OK Spike. I assumed that this thread was based on the premise of using the TruTrack ADI as a back-up for an EFIS attitude indicator. While I can see an instructor making you fly partial panel IMC slowflight for training and proficiency, in an actual emergency requiring use of the back-up instrument, you should not be flying the aircraft outside of a comfortable flight envelope. If ATC restricts your speed outside of this comfort envelope, the only response by a seasoned pilot would be, "Unable."

For many of the reasons listed in the posts above, I would not use this instrument as a primary attitude indicator, because it simply is not. However, as a standby instrument, it is probably the best all-round, least expensive presentation I have seen. There is a much better one on the panel of my ride at work, but since just one copy of the 'integrated standby instrument' would buy two or more completed, IFR equiped RV's, I plan to use the TruTrack unit in my RV.

Pat

[Spike]

I never took a position as to what the pilot should do, or what positions that they should get themselves into. I only answered the question as to why they would practice such a thing.

I personally dont think I agree with the idea of using that instrument as a backup for the AI. I would think its presentation would force me to be cognizant of what it is not. Id rather just have the VSI & T&B since its the same. The only thing about it that I would appreciate would be the heading output to replace the DG. But then any modern day GPS would probably get you close enough.