Need NAV unit that drives a Flight Director

R

RamJet1

Filing Flight Plan
Joined
Feb 3, 2023
Messages
5
Display Name
Display name:
RamJet1
Installing badic IFR panel in a Cessna 172 with two GI 275. What nav units will drive a flight director (command bars), no autopilot installed.

It's unclear which units drive command bars and which ones don't

Thx
 
I thought you needed an autopilot to get flight director. I'm curious to see if my understanding was wrong.
 
There is no way to get a flight director on the GI 275 without an autopilot
 
FD on our 275 comes from the KFC-200 autopilot.
 
Autopilot required is my understanding as well. Hard to imagine a NAV unit being able to give a bank command without knowing attitude and/or turn rate.
 
Is there any other display (G5?) that can be driven by a NAV unit (Garmin430/530/650) that has a flight director/command bars? Avionics shops can't seem to answer my question.

Thanks, Tom
 
As far as I know, none. I talked to Dynon about this. They intended to have that ability with the skyview, but we’re never able to get it to work properly without the autopilot servos installed.
 
G5 has flight director bars, but needs an AP to drive them.
 
Gps does not provide all the data needed to drive a flight director.
 
RamJet1 said:
Is there any other display (G5?) that can be driven by a NAV unit (Garmin430/530/650) that has a flight director/command bars?
Click to expand...
Short answer: No, there is not.

Longer answer: You are asking the wrong question. A NAV unit never drives flight director command bars. It's just not how these pieces work/are connected. Instead, a NAV unit drives deviation bars on a CDI or HSI.

- Martin
 
I suppose in theory director system can be part of an autopilot or exist on aircraft that do not possess full autopilot system, but modern hardware drives the FD from the AP.
 
Clip4 said:
I suppose in theory director system can be part of an autopilot or exist on aircraft that do not possess full autopilot system, but modern hardware drives the FD from the AP.
Click to expand...

T-38A had a flight director but no autopilot. I am not sure how it was driven.
 
Clip4 said:
I suppose in theory director system can be part of an autopilot or exist on aircraft that do not possess full autopilot system, but modern hardware drives the FD from the AP.
Click to expand...

Pinecone said:
T-38A had a flight director but no autopilot. I am not sure how it was driven.
Click to expand...

In a way, every autopilot has a flight director function, though not every such system can display the flight director output on a PFD. The flight director is the "brain" of the autopilot; it takes inputs from the mode control panel and the various sensors (gyros, NAV radios, GPS, airspeed, altitude, etc.) and turns it into pitch and roll commands. Those pitch and roll commands can, in some installations, be displayed as cues on the PFD - we then call that "Flight Director". The commands can also drive servos and actuate flight control surfaces, and we call that "coupled".

So it's possible to have a flight director with no servos (like the T-38A example @Pinecone mentioned); it's also possible to have a fully-coupled autopilot which computes but does not display its pitch and roll guidance PFD - they just drive the servos.

- Martin
 
I flew a Beech 1900 for US Air Express years ago with no autopilot but we had a flight director that would drive us down the ILS with command bars. There must be a way to do this. It's such a basic function, OTHERWISE THE ENTIRE GA WORLD IS FLYING RAW DATA APPROACHES?????
 
Martin Pauly said:
it's also possible to have a fully-coupled autopilot which computes but does not display its pitch and roll guidance PFD - they just drive the servos.

- Martin
Click to expand...

MANY of those around. Like my KAP-150. :D

I forgot, when I flew the A-10A, it also did not have an autopilot, but it did have a dual cue FD.
 
RamJet1 said:
I flew a Beech 1900 for US Air Express years ago with no autopilot but we had a flight director that would drive us down the ILS with command bars. There must be a way to do this. It's such a basic function, OTHERWISE THE ENTIRE GA WORLD IS FLYING RAW DATA APPROACHES?????
Click to expand...

Again, it is NOT a function of the nav. An FD without autopilot is basically all the brains of an autopilot, without the brawn (servos) to drive the flight controls.

It takes INPUT from the nav, but the nav does not have all the other information needed.
 
So for example, for this to work, I could use two GI 275s, a Garmin 430W and some kind of an autopilot head to that will integrate and communicate with the other hardware? Anyone have any ideas of such a setup?
 
RamJet1 said:
So for example, for this to work, I could use two GI 275s, a Garmin 430W and some kind of an autopilot head to that will integrate and communicate with the other hardware? Anyone have any ideas of such a setup?
Click to expand...
How about adding a GFC500 to the items you mentioned? That would give you a Flight Director - and a full autopilot. I’m not aware of a product approved for a Cessna 172 that would give you Flight Director without also giving you the rest of the autopilot.

- Martin
 
Curious why an FD is such a strong requirement? Your dual 275's will display basically all the info you need to fly an approach. I added a GFC500 to my plane to get an AP that would fly a fully coupled approach. It also gave me command bars. I pretty much never look at them.
 
Without command bars, you're just flying raw needles, correct? Why make life difficult for yourself when you can just fly up in the command bars and they keep you on a perfect approach path laterally and vertically. Unless I'm missing something.
 
In that case, why not make it even easier and have the AUTOPILOT fly the airplane???????

Since there is no product on the market for GA to have FD without an autopilot, you get the have the autopilot and make life easier.
 
Alas, the experimental world has efis systems that provide flight directors without an actual autopilot installed. The GRT lines do and their MiniGa can be used in certificated aircraft, and it has the flight director function. It can't be used for IFR flight though.
 
Funny, I always FD without an autopilot was a waste. A 275 presents the approach quite pleasantly and easy to fly.
 
You must log in or register to reply here.
Back
Top