Confusion with my KFC-150, G5 HSI, GI-275 and a 530W

[rbp]

6 hours ago, jaylw314 said:

Yes, my DME is not paired to the 530 in terms of frequency tuning.  I know it can, and I'll probably do that next time I'm in the avionics shop, but I'm trying to avoid them as long as I can

 

with all due respect, any comment you make about how you like to setup your 530 should be prefaced with this, and with the fact that you don't (always?) load the ILS approaches into the flight plan, otherwise you're just going to confuse people who want to use their equipment in the way it was intended.

[rbp]

On 1/28/2023 at 5:54 PM, PT20J said:

Exactly. The command bars are simply a visual display of what the autopilot is doing. The only difference between FD and AP modes is engagement of the servos.

for clarification:

the KFC150 + KFC225 and the GFC500 that I have flown with all have two buttons: FD for flight director and AP for autopilot.

FD calculates the attitude of the plane to achieve the desired flight path specified by the selected horizontal and vertical modes, and the calculated attitude is displayed on the command bars of the AI for the pilot to follow.

AP engages the servos to automatically follow the command bars.

[Fly Boomer]

11 hours ago, rbp said:

AP engages the servos to automatically follow the command bars.

This is more in line with my belief (above) that the AP was following the command bars, not driving them.  

[PT20J]

15 minutes ago, Fly Boomer said:

This is more in line with my belief (above) that the AP was following the command bars, not driving them.  

The autopilot has a computer that drives both the command bars and the servos. It's the same thing. The command bards are just a visual indication of the computer output. If you manually follow the command bars you are just doing what the servos would be doing if you switched from FD to AP. 

[Fly Boomer]

14 minutes ago, PT20J said:

The autopilot has a computer that drives both the command bars and the servos. It's the same thing. The command bards are just a visual indication of the computer output. If you manually follow the command bars you are just doing what the servos would be doing if you switched from FD to AP. 

I don't know where the wires go, but I have always thought the navigator was driving -- command bars only, or command bars plus AP.

[Jake@BevanAviation]

FD drive always comes from the flight computer (legacy systems). 

[Fly Boomer]

Just now, Jake@BevanAviation said:

FD drive always comes from the flight computer (legacy systems). 

By "flight computer" you mean autopilot?  As I said, I don't know what wires are hooked to what, but it seems to me that, even if the FD is wired to the AP, the AP is getting it's info regarding the flight plan from the navigator.  Isn't it the navigator that supplies the info to the FD?  As well as the autopilot, if it's engaged?

[0TreeLemur]

I'm new to this but learning, as I understand it the KFC-150 autopilot system uses the KC-192 Flight Computer, which is the controller for the autopilot system installed in your panel with buttons on it.  

The KC-192 gets attitude information from a fancy BK AI, or a digital AI (Garmin 275 or Aspen), and desired heading/CDI info from a fancy BK HSI, or digital HSI.  If in the correct mode (HDG, NAV) the computer computes the control inputs needed to follow that course and sends that information back to the fancy AI, which then displays the computer output on the V-bars if in FD mode.   If in AP mode as well, the flight computer also commands the servos to do what it computed.

The V-bars show flight computer output either way.

[rbp]

1 hour ago, Fly Boomer said:

By "flight computer" you mean autopilot?  As I said, I don't know what wires are hooked to what, but it seems to me that, even if the FD is wired to the AP, the AP is getting it's info regarding the flight plan from the navigator.  Isn't it the navigator that supplies the info to the FD?  As well as the autopilot, if it's engaged?

“Autopilot” Has two meanings:

The generic meeting is the entire auto pilot system  

It  includes a flight director (FD), a computer which figures out the attitude of the plane to follow the desired flight path,  As well as the specific thing called the auto pilot (engaged by pressing the AP button) That controls the servers based on the flight directors calculations 

 

 

The AP button 

[PT20J]

2 hours ago, Fly Boomer said:

By "flight computer" you mean autopilot?  As I said, I don't know what wires are hooked to what, but it seems to me that, even if the FD is wired to the AP, the AP is getting it's info regarding the flight plan from the navigator.  Isn't it the navigator that supplies the info to the FD?  As well as the autopilot, if it's engaged?

Autopilot kind of refers to the entire system. The KFC 150 has a flight computer KC 192 that is the brains. It is the panel mount unit that has the pushbuttons and display. Look back up this thread to the diagram I posted that shows all the components and how they interconnect. The FD is part of the autopilot. The  autopilot computer gets navigation information from the navigator, course and heading information from the HSI and attitude information from the attitude gyro, and then it computes a pitch and roll solution which is displayed on the FD. If you engage the autopilot, it also drives the servos to fly the airplane.

[Jake@BevanAviation]

@PT20J you are 100% correct.  The autopilot system uses multiple boxes to process the incoming information and send the commands for correction out the the servos to control the aircraft.  The flight computer (KC192) takes in information from the AI, HSI and primary navigator. Sums all this information together and produces a correction drive for the servos.  
The FD is a function of the autopilot flight computer. It gives a visual indication on the AI of what the system is trying to do based on the information it is given. The FD bars should always mimic the servo drive. If you ever have separation in the FD bars vs what the aircraft is doing with the autopilot engaged, you have a problem within the system. 

[skyfarer]

Thank you all for your replies.  Today it's a nice VFR day so I went out with my CFII and we got it to couple with a VOR. The button sequence was exactly what several of you said it would be: 530 set to VLOC, KF-150 set to NAV.  Then I flew an ILS and while it blew through the localizer, it finally corrected and flew the LOC and GS perfectly. I started the intercept with the AP in HDG mode, and pressed APR before intercept.  The APR light blinked until it crossed the localizer then it went steady. Near the GS, the GS light came on also.

The winds, traffic, and time forced me to shoot an RNAV LP instead of the LPV I wanted, but I set it up anyway to see what would happen. Approach was loaded into the 530, AP was set to HDG mode, and G5 HSI GPSS off. It flew the IAF dog leg then on the final approach it hung around one dot right of course, but it was stable. The 530 displayed LP+V mode, I was not expecting any vertical guidance.  I managed the descent to FAF (2300msl) but before intercepting the GS, I hit APR to arm it and see what it would do. It coupled the GS for the last 1000 feet to circling minimums (1180msl) which is where I cut it off to circle over to the active runway. We're going to practice some more RNAV's and see how things go.

I got Crystal Avionics on the phone today, they took the tail number and work order numbers and are going to get me the missing paperwork to get my POH complete for the G5 and GI275 installs.

Again, thank you all for your replies, they were all very helpful. 

[rbp]

in case no one has mentioned it "+V" is advisory only