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727 Captain >> 727 Captain >> AUTOPILOT-the only thread please
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Message started by dandi99 on Feb 12th, 2009 at 5:08pm

Title: AUTOPILOT-the only thread please
Post by dandi99 on Feb 12th, 2009 at 5:08pm
Hy guys,

I have two questions about the Autopilot of the B 727
How can I use the FSX-Flight Plan or the GPS for an auto flight?
How can I adjust the V/S

Thanks
David

Title: Re: Autopilot
Post by Bob Markey on Feb 12th, 2009 at 8:30pm
Hi David.

The B727 did not come equipped with GPS from the factory (GPS didn't exist during its production run).  They have been retro-fitted though, and CS has silently implied that a GPS system may be provided in the future, as one is shown ahead of the control stand.

It will require a NAV/GPS switch, which I've not seen in the cockpit, and not investigated to see if one exists in the configuration.  We will maybe have to wait for the next manual to be released and/or the next SP to know for sure.

If you have a key set for NAV/GPS, you may wish to test this:

1) tune your NAV radio to some VOR or ILS that's nearby that you can receive a signal, and turn the course knob until it shows flight path deviation.
2) program the Garmin 500 GPS for a direct route someplace.
3) Press the key you have assigned for NAV/GPS, and see if the HSI deviation changes.

If so, then you can set this keypress to select the GPS instead of NAV, and use the VOR/LOC mode on the AP to track the GPS waypoint data.

I've not tested this, so I couldn't tell you if it works or not.

As for your FP questions-

The oldschool sperry AP in the B727 could only control pitch and roll.  It would not calculate pitch variance to maintain a vertical speed.

If you engage the AP shortly after take-off, it goes into hold mode for the command selected.  There are two commands on this AP, AIL and ELEV.  AIL being roll, ELEV being pitch.  You can't engage ELEV without AIL already engaged.

So, in our hypothetical situation... you roll out, V1, VR, pitch up ~10 degrees, hold it there thru V2, reach down and flip on the AIL/ELEV commands and let go.  At this point, the AP will hold your roll right where you left it (hopefully wing level) and hold your pitch right where you left it (hopefully still near 10 degrees nose up).

It will stay exactly like this unless you tell it otherwise.

So, how do you tell it otherwise?

There are two ways.  With the pitch/roll command knob to the left of the engage levers, or with the Alt/Hdg hold switches to the right of the engage levers.

If you turn the pitch roll knob left, the plane will begin to roll left, to the approximate degrees commanded on the knob.  If you nudge the knob forward, a few times, you will convince the AP to nose down attitude slightly.  Nudge it a few more times, and it will move a little more.  The difference is minor, it may take 20 "nudges" to change the pitch by 10 degrees, I've never counted to be honest.

This is where you're changing the vertical speed, but you must be PIC when doing this... your attitude and your airspeed will both affect the rate of climb/descent, so 10 degrees at 160 knots is not going to climb the same as 10 degrees at 250 knots.  And, since the VSI is broken on the plane right now  :'( you'll have to watch the altimeter and do some best guesses for how fast you're really climbing or descending.

The second way of telling the AP what to do is to use one of the hold switches.  Hdg Hold is what we're all used to from any AP, for the most part.  Click it on, and the plane will hold its present heading, and level the wings if it's banked any.  Turn the heading bug, and it will turn to that heading.  Alt Hold is sort-of what we're used to with any AP, but it says "at the very moment this switch is engaged, level the plane and maintain the altitude at that very moment to the nearest hundred feet."

To explain differently what I just said, let's take this example:

We're climbing about 1000 fpm towards our target cruise altitude.
As we get to 900 ft below (the Alt Alert chime sounds) we begin commanding the plane to slowly pitch nose down to slow the rate of ascent.  As we get within about +/- 49 feet from the target altitude, we flip the Alt Hold switch.  At this point, the plane finishes rolling out flat, and re-trims itself to hold that altitude as best as possible, regardless of how the airspeed rises or drops.

Or, you could climb 6000 fpm and flick the Alt Hold switch and the plane will continue climbing hundreds (or thousands) of feet above that, and then will begin to pitch down to descend back to that altitude.

So, If my target is FL230, I would command it to hold somewhere around 22,951 ft.  If I command it to hold before that, it will choose to hold 22,900.

So yeah, in short, there is no cap alititude setting (the altitude setting only sets off the alt alert chime and light) and there is no VS setting.  It's up to the pilot to tell the AP how to fly the plane.

Title: Re: Autopilot
Post by dandi99 on Feb 12th, 2009 at 10:58pm
Thanks for this great answer! ;D ;D ;D ;D


Title: Re: Autopilot
Post by afmoose on Feb 13th, 2009 at 2:30am
You can assign a keystroke or joystick button within FSX to switch between Nav and GPS. I have done this and it works great. Hit the switch and then turn on VOR/LOC mode on the autopilot. You just have to remember to hit the switch again before trying to capture a localizer and glideslope.

Gary

Title: Autopilot Manipulation
Post by phil29 on Feb 12th, 2009 at 8:15pm
Is there any way to assign a key or joystick assignment to control the autopilot when it is in MAN mode?  I have a little trouble accurately manipulating the pitch and roll controller of the autopilot.  If there isn't a way to assign a key to those functions, it may be advisable to add it in.  Anyone have any advise?

Title: Re: Autopilot Manipulation
Post by Bob Markey on Feb 12th, 2009 at 8:33pm
I don't think there is, unless maybe you have a registered copy of FSUIPC and if CS has made it possible to manipulate through FSUIPC.

I find it impossible to use the pitch/roll knob in the VC, as any pitch command invariably gets interpreted as a desire to roll.

I have the 2D pop-up AP panel on my 2nd monitor at all times for handy use, or you can use the buttonbar panel or press Shift-4 to access it.

So long as you click above center or below center on the 2D panel, it always interprets it as a pitch change and never a roll change.

Hope it helps. 8-)

Title: Re: Autopilot Manipulation
Post by phil29 on Feb 12th, 2009 at 9:21pm
I didnt even consider using a popup panel since the 727 was designed almost primarily for VC use.  Thats cool then, ill just use the 2D popup to manipulate it for the time being.  Thanks.

Title: Re: Autopilot Manipulation
Post by Michael2 on Feb 12th, 2009 at 9:25pm
The pop-up is certainly easiest, but I have found that the trick in the VC for the pitch control is to move the mouse vertically on the monitor, regardless of how the control appears to be angled in the VC.  Failure to move the mouse vertically with respect to monitor as the only reference will result in commanding a turn.

Title: Re: Autopilot Manipulation
Post by Bob Markey on Feb 12th, 2009 at 9:52pm
Interesting Michael.  I had not considered that the control would be relative to mouse orientation rather than knob orientation.

It certainly would be nice to have a way to control it from an external source, though.  Imagine the people who may wish to build something like a home simpit panel for it.

Title: Re: Autopilot Manipulation
Post by phil29 on Feb 13th, 2009 at 5:02am
Right, I realized that as well, the only problem is that its still incredibly sensitive and usually on something like a departure there isnt a whole lot of time to surgically try and manipulate the controls.  I almost always end up banking when I try to move it, but the popup is working great.

Title: Re: AUTOPILOT-the only thread please
Post by Michael2 on Feb 16th, 2009 at 6:23am
Here is a copy and paste of the last support ticket I submitted. Does anyone else have this problem:

The autopilot heading select mode stops working when altitude hold is turned off.
When I change the heading bug on the VSI the autopilot begins a turn.  If I then turn off altitude hold in order to descend or climb, the aircraft then holds the current heading, even though the turn to the bug has not completed.
Turning off altitude hold should not have any effect on the heading select mode.

Title: Flight director problems.
Post by Michael2 on Feb 15th, 2009 at 11:34pm
Does it work for anyone? I can't get it to work and I have no reply to my support ticket.  The only way it will do anything is if I turn the autopilot on and then off.  It will then work (to some degree) in response to the autopilot settings, but it never responds to the setting I have on the flight director itself.  Futhermore, once the bars come out, there is no setting that will remove them.

Is there something wrong with my install, or is it equally broken for everyone?

Title: Re: AUTOPILOT-the only thread please
Post by Bob Markey on Feb 16th, 2009 at 7:44pm
Michael,

There are a few "glitches" in the AP yet.  Should be fixed in the next SP, I would hope.

I haven't experienced an issue with the Alt Hold turning off the Hdg Hold.  What I do have happen is when I switch from MAN to NAV/LOC, the Alt Hold also turns off, even though NAV/LOC has nothing to do with Alt.  I have to constantly remind myself that I will have to re-engage Alt Hold when I make the switch.

Another thing is when switching from NAV/LOC to AUTO GS, if I an not yet in range to intercept either the localizer or the glideslope, it still will turn off both Alt and Hdg holds.  I don't think it's supposed to turn off either until it's in position to begin interception.

I don't know if that's accurate or not, but if it's something that was overlooked in testing, it will hopefully be fixed in the first SP release.

Title: Auto-Pilot
Post by fridrik on Jun 2nd, 2009 at 1:16pm
Hi there simmers

I just bought the 727 package and i have a question,where is the autopilot for the speed?
Can someone tell me where Auto-Pilot engage for the speed is on the panel?
I want to go head and hold the speed for the landings :-?

regards
Fridrik

Title: Glide slope capture hosed?
Post by JayG on Mar 29th, 2009 at 3:36pm
Great looking and flying plane BUT, I have yet to find the secret to capturing the GS with the AP. I always intercept from below and as soon as I engage the AP for APPR the plane dives even though I am below the GS.

Its not big deal to hand fly the approach, but it should be working. Is it just me or are others having this problem? I thought I saw other threads on this but I can't find them now.

Title: Re: Glide slope capture hosed?
Post by Christopher Dittmar on Mar 30th, 2009 at 3:10am
What other modes are you in when you activate the approach?  i found on mind that sometimes, depending on what mode I am in, altitude hold likes to kick OFF when I switch to approach mode.  I have started the habit of when I switch on the approach mode, I immediately check and get ALT hold back on.  It will kick off automatically on G/S capture.

Title: Re: Glide slope capture hosed?
Post by JayG on Mar 30th, 2009 at 3:29am
Ya Alt Hold does kick off, but it shouldnt dive since the trim is set. If its working for you I guess I need to try a few different things, tks for the reply

Title: Controlling pitch while autopilot is on
Post by David Zill on Jun 6th, 2009 at 3:01am
How is this done?

Title: Autopilot
Post by soldano on Jul 12th, 2009 at 12:00am
I understand that this is a "Pilots bird", but if it has an autopilot, we can expect it to work OK.- In my case is impossible to make the plane follow the glide slope in AutoGS mode, even when selected about 15 miles far from the airport, aligned with the localizer and before intercepting it.-
I found that the only functions that work are: Nav LOC and HDG Select.-
I dont understand the logic of the AP altitude control.- I cannot make it to mantain the selected altitude in the altitude set control, also everytime I make a turn using AP heading select, it pitches down.-
Please somebody can explain me how the alt hold works ?
The operations manual nothing explains about that, and only refers to a "Category II discussion later in this chapter.." which I couldnt find.-
Thanks

Title: Re: Autopilot
Post by soldano on Jul 20th, 2009 at 11:14pm

soldano wrote on Jul 12th, 2009 at 12:00am:
I understand that this is a "Pilots bird", but if it has an autopilot, we can expect it to work OK.- In my case is impossible to make the plane follow the glide slope in AutoGS mode, even when selected about 15 miles far from the airport, aligned with the localizer and before intercepting it.-
I found that the only functions that work are: Nav LOC and HDG Select.-
I dont understand the logic of the AP altitude control.- I cannot make it to mantain the selected altitude in the altitude set control, also everytime I make a turn using AP heading select, it pitches down.-
Please somebody can explain me how the alt hold works ?
The operations manual nothing explains about that, and only refers to a "Category II discussion later in this chapter.." which I couldnt find.-
Thanks


As there are no replies I assume I am the only one who has such problems with the AP, and everybody is quite happy with it.-
At least I want a reply about what is the "altitude set control" for ?
Thanks
(I sent a ticket to support a week ago, but got no reply)

Title: Re: AUTOPILOT-the only thread please
Post by JETPILOT on Jul 20th, 2009 at 11:33pm
I think your inquiring ablut the altitude alert? It's simply an aural warning and visual reminder when climbing or descending to an altitude. It has no autopilot function.

Title: Re: AUTOPILOT-the only thread please
Post by soldano on Jul 21st, 2009 at 11:19pm

JETPILOT wrote on Jul 20th, 2009 at 11:33pm:
I think your inquiring ablut the altitude alert? It's simply an aural warning and visual reminder when climbing or descending to an altitude. It has no autopilot function.



Thanks, it is indeed the altitude alert, I found it in the manual.-
About the AP problem, in your case, does it holds altitude steadily without ups and downs at first ?

Title: Re: AUTOPILOT-the only thread please
Post by JETPILOT on Jul 22nd, 2009 at 2:42am
My autopilot functions normally with no altitude deviations at all.

Title: Re: AUTOPILOT-the only thread please
Post by soldano on Jul 23rd, 2009 at 11:00pm

JETPILOT wrote on Jul 22nd, 2009 at 2:42am:
My autopilot functions normally with no altitude deviations at all.



Even when you turn using AP heading select ?

Title: Re: AUTOPILOT-the only thread please
Post by Tyrion on Jul 24th, 2009 at 6:16pm
Made a couple of flights using AP, and everything works fine here too.
Used alt hold, hdg hold, turning with hdg hold, nav hold (using VOR's) and app mode (using ILS)...
no problems at all...

Lars

Title: Re: AUTOPILOT-the only thread please
Post by JETPILOT on Jul 24th, 2009 at 8:37pm

soldano wrote on Jul 23rd, 2009 at 11:00pm:

JETPILOT wrote on Jul 22nd, 2009 at 2:42am:
My autopilot functions normally with no altitude deviations at all.



Even when you turn using AP heading select ?


Yes my autopilot works in all situations.

Title: Re: AUTOPILOT-the only thread please
Post by soldano on Jul 25th, 2009 at 8:43pm
Well, after a reinstall, now it works OK, I love this 727.-

Title: Re: AUTOPILOT-the only thread please
Post by Tyrion on Jul 25th, 2009 at 8:53pm
Glad you got it to work finally...
indeed lovely bird!

Title: Re: AUTOPILOT-the only thread please
Post by SMfsx on Aug 1st, 2009 at 9:28am
Could you help me with the AP?

I have no problems with MAN AP at all, as a matter of fact it works perfect.
My problem is with NAV LOC
The manual 2.2 says
"In the NAV LOC position, the autopilot will maneuver the airplane to capture and track, correcting for wind, a localizer course or a VOR radial as selected on the course arrow of the Captain's course indicator."
I have a VOR tuned in and a course set but I can never get the NAV LOC to turn/engage to fly the course.

Thank you for any help.

Title: Re: AUTOPILOT-the only thread please
Post by pdahero on Nov 11th, 2009 at 5:49am
I'm having trouble with the AP, too  :'( (I have CS727 for FS9 and it worked perfectly.)

I cannot get the AP to maintain altitude properly. The other day it worked and maintained 8,000 feet, but when I climbed to 29,000 it wouldn't work. Specifically, the aircraft begins to nose-up. I tried adjusting the pitch up and down, (and throttle) but in 10 minutes of trying, the aircraft started porposing up and down.

Am I doing something wrong? Can't I just turn on the AP and select 'Alt hold'?

Title: Re: AUTOPILOT-the only thread please
Post by Matt2218 on Nov 18th, 2009 at 12:23am

Tyrion wrote on Jul 24th, 2009 at 6:16pm:
Made a couple of flights using AP, and everything works fine here too.
Used alt hold, hdg hold, turning with hdg hold, nav hold (using VOR's) and app mode (using ILS)...
no problems at all...

Lars


Lars - I had one question for you.  If you activate only the 'aileron master' switch (leave the elevator master switch off) can you control the pitch of the aircraft using the yoke?

As I understand it, you are supposed to be able to set the aileron master to hold your heading or stay on the localizer while you adjust pitch manually with the yoke.  On my machine the CS 727 AP doesn't work that way though...when I flip the aileron master it instantly locks my pitch attitude as well, with the elevator master off.

I've submitted a ticket, but in the mean time I tweaked the xml part of my 2D autopilot gauge and can now operate the autopilot elevator master switch  to control pitch independently, the way it is supposed to work...unfortunately haven't figured out how to get the elevator master switch indication to be right in any mode other than 'manual'. When I hit altitude hold the elevator master switches 'off' even though it is still on technically because it is holding altitude!

Wish I knew how to program in C++   :D

Could be something specific to my setup, but I hope it is addressed in the next update.

Title: Re: AUTOPILOT-the only thread please
Post by Tyrion on Nov 18th, 2009 at 5:54pm
I haven't tried that exactly.
Haven't done any long flights in this bird recently, quite busy with other things.
Sorry, I wouldn't know the answer to your question.

Lars

Title: Re: AUTOPILOT-the only thread please
Post by Matt2218 on Nov 20th, 2009 at 12:13pm
Thanks Lars...It's a minor point; frankly I fly by hand most of the time anyway.  

It is nice though to have the aircraft track the localizer or VOR radial automatically and adjust climb/descent manually.  I hope they can fix it for the next update.

Title: Re: AUTOPILOT-the only thread please
Post by Berlopez on Nov 21st, 2009 at 8:54pm
JayG: I'm in the same boat as you right now with thew 727. Auto approaches and ILS's...
Today I managed my first ILS approach, I'm not pround of it because I landed faaaaaaaaaaar away from the runway That is the plane began it's auto descend too soon. The capture of the ILS heading was straight on. But the maintaining of altitude,unless I'm doing/ expecting something (?) was way too soon. It landed the plane a good 5 miles out in front of the runway????? :-/

Title: Re: AUTOPILOT-the only thread please
Post by Matt2218 on Dec 6th, 2009 at 1:38pm
Captain Sim -

If you are still reading this thread...

I modified the autopilot .xml to make it behave more like the real 727 Sperry in terms of pitch control...I also finally got the 'elevator master' switch to properly indicate its status when in other than manual mode.

I sent you a link to the updated gauge via the trouble ticket system; I'd recommend you try it out and see if it works better than the old one.

Title: Re: AUTOPILOT-the only thread please
Post by HoggyDog on Dec 12th, 2009 at 7:20pm
I am having difficulty with the autopilot properly capturing localizers and glideslopes. With pre-intercept conditions of: AP set to Heading Hold and Alt Hold, course needle set to desired course (final approach course) and approaching the localizer on a heading resulting in 20 degrees or less for an intercept angle and an altitude far below the GS, I switch the AP to "Auto/GS" when cleared for the approach.

As the localizer needle-segment "comes alive" on the CDI and starts to move toward a centered "on course" indication, the AP does *nothing.* It continues to do *nothing* until the CDI indicates that we have just flown through the localizer... then it abruptly turns the airplane back toward the localizer using max bank angle... flies back through the localizer... overcorrects again... flies through the localizer again... and basically zig-zags around the localizer all the way down final.

Meanwhile, the GS needle begins to move down the side of the CDI. So, true to its disposition, the AP does *nothing* until we have flown through the GS, at which point the AP abruptly noses the airplane over into a dive... and we porpoise endlessly, flying through the GS at least 5 times as we zig-zag around the localizer. Sometimes we get near the runway, sometimes we don't.

In short, my AP seems to stay about 2-3 seconds behind the airplane at all times. It's not my computer- I have great framerates (minimum 25 fps) at all times and no scenery-load "glitching" even with UTX and GEX running... nothing about flying in FSX is "tardy" for me except the AP in this particular airplane, so my computer is not 2-3 seconds behind the Sim... it's really just the AP that can't seem to keep up.

Even worse, several passengers have sent gratuitously-nasty letters to my airline, featuring my name and using unjustified phrases such as "ham-fisted oaf" and "needs to go back to his previous career as a blacksmith" and "surprised the wings stayed on the airplane." Management has taken to occasionally asking me if I miss my days of being a FE on the 727...  ;D

I have carefully read the manuals (Systems and Ops), as well as the excellent mini-tutorial at the head of this thread, and I believe that I am setting everything correctly for LOC/GS captures. My expectation is that the old Sperry will "notice" the impending LOC and GS capture as soon as the needle comes alive and begin turning toward the course (or pitching down toward a normal ILS descent gradient) as the needles get a dot or two BEFORE center, not AFTER center. The result would be a relatively smooth and accurate capture with MINIMAL "hunting" back and forth.

Since there are people here who say that "everything works fine for me" can someone please tell me if Auto/GS with settings as I described above works for you without zig-zagging and porpoising all the way down final while using up all the barf bags aboard, or if I am setting something incorrectly?

Thanks!

Title: Re: AUTOPILOT-the only thread please
Post by HoggyDog on Dec 12th, 2009 at 7:57pm

Matt2218 wrote on Dec 6th, 2009 at 1:38pm:

I modified the autopilot .xml to make it behave more like the real 727 Sperry in terms of pitch control...I also finally got the 'elevator master' switch to properly indicate its status when in other than manual mode.

I sent you a link to the updated gauge via the trouble ticket system; I'd recommend you try it out and see if it works better than the old one.


Matt, do you know if CS has done anything with this? I just bought the CS 727 a  week ago- so I have no way of knowing whether or not CS has "fixed" this, except to note that my AP seems to work as expected except in Auto/GS mode (see my prev. post).

Title: Re: AUTOPILOT-the only thread please
Post by Richard Portier on Dec 12th, 2009 at 8:48pm

HoggyDog wrote on Dec 12th, 2009 at 7:20pm:
I am having difficulty with the autopilot properly capturing localizers and glideslopes. With pre-intercept conditions of: AP set to Heading Hold and Alt Hold, course needle set to desired course (final approach course) and approaching the localizer on a heading resulting in 20 degrees or less for an intercept angle and an altitude far below the GS, I switch the AP to "Auto/GS" when cleared for the approach.

As the localizer needle-segment "comes alive" on the CDI and starts to move toward a centered "on course" indication, the AP does *nothing.* It continues to do *nothing* until the CDI indicates that we have just flown through the localizer... then it abruptly turns the airplane back toward the localizer using max bank angle... flies back through the localizer... overcorrects again... flies through the localizer again... and basically zig-zags around the localizer all the way down final.

Meanwhile, the GS needle begins to move down the side of the CDI. So, true to its disposition, the AP does *nothing* until we have flown through the GS, at which point the AP abruptly noses the airplane over into a dive... and we porpoise endlessly, flying through the GS at least 5 times as we zig-zag around the localizer. Sometimes we get near the runway, sometimes we don't.

In short, my AP seems to stay about 2-3 seconds behind the airplane at all times. It's not my computer- I have great framerates (minimum 25 fps) at all times and no scenery-load "glitching" even with UTX and GEX running... nothing about flying in FSX is "tardy" for me except the AP in this particular airplane, so my computer is not 2-3 seconds behind the Sim... it's really just the AP that can't seem to keep up.

Even worse, several passengers have sent gratuitously-nasty letters to my airline, featuring my name and using unjustified phrases such as "ham-fisted oaf" and "needs to go back to his previous career as a blacksmith" and "surprised the wings stayed on the airplane." Management has taken to occasionally asking me if I miss my days of being a FE on the 727...  ;D

I have carefully read the manuals (Systems and Ops), as well as the excellent mini-tutorial at the head of this thread, and I believe that I am setting everything correctly for LOC/GS captures. My expectation is that the old Sperry will "notice" the impending LOC and GS capture as soon as the needle comes alive and begin turning toward the course (or pitching down toward a normal ILS descent gradient) as the needles get a dot or two BEFORE center, not AFTER center. The result would be a relatively smooth and accurate capture with MINIMAL "hunting" back and forth.

Since there are people here who say that "everything works fine for me" can someone please tell me if Auto/GS with settings as I described above works for you without zig-zagging and porpoising all the way down final while using up all the barf bags aboard, or if I am setting something incorrectly?

Thanks!



Hello,

Concerning Auto/GS approach mode, it works without problem when the plane is EMPTY (just the 3 officers + 3* 20 or 30 percent of fuel)

I made several touch and go at KORD with not problem.

BUT if the bird is full passengers + some luggages in cargo + 10 or 20 percent of fuel (typical config after a trip), it seems react like you wrote.

Maybe a clue for some fine adjustement in plane.cfg or other files...!?

Have you tested with an empty plane ?

Regards.

Richard.



Title: Re: AUTOPILOT-the only thread please
Post by Matt2218 on Dec 12th, 2009 at 9:46pm

HoggyDog wrote on Dec 12th, 2009 at 7:57pm:

Matt2218 wrote on Dec 6th, 2009 at 1:38pm:

I modified the autopilot .xml to make it behave more like the real 727 Sperry in terms of pitch control...I also finally got the 'elevator master' switch to properly indicate its status when in other than manual mode.

I sent you a link to the updated gauge via the trouble ticket system; I'd recommend you try it out and see if it works better than the old one.


Matt, do you know if CS has done anything with this? I just bought the CS 727 a  week ago- so I have no way of knowing whether or not CS has "fixed" this, except to note that my AP seems to work as expected except in Auto/GS mode (see my prev. post).


Not as far as I know...they said they would look at it though.

Just to be clear, my mods to the AP weren't targeted at how it tracks the localizer/GS...I just changed how the switches functioned.  My AP seems to work just fine, except that sometimes it doesn't grab the glideslope properly...usually when I've just loaded a saved flight.

Title: Re: AUTOPILOT-the only thread please
Post by HoggyDog on Dec 13th, 2009 at 5:45pm

Richard Portier wrote on Dec 12th, 2009 at 8:48pm:

Concerning Auto/GS approach mode, it works without problem when the plane is EMPTY (just the 3 officers + 3* 20 or 30 percent of fuel)

I made several touch and go at KORD with not problem.

BUT if the bird is full passengers + some luggages in cargo + 10 or 20 percent of fuel (typical config after a trip), it seems react like you wrote.

Maybe a clue for some fine adjustement in plane.cfg or other files...!?

Have you tested with an empty plane ?


Richard, thanks, it never occurred to me that aircraft weight would have anything to do with AP performance, and I have NOT tested with an empty airplane- all of my approaches in this fine bird have been at the end of a 1-2 hour flight that started with full fuel and about 50-80% passenger/baggage loads.

I will do some testing with an empty airplane and see if that cures the AP problems, but even if it does, I hate to have to placard the AP "WARNING: APPROACH MODE UNUSABLE UNLESS AIRCRAFT IS EMPTY"  :D

Title: Re: AUTOPILOT-the only thread please
Post by HoggyDog on Dec 13th, 2009 at 5:53pm

Matt2218 wrote on Dec 12th, 2009 at 9:46pm:

Just to be clear, my mods to the AP weren't targeted at how it tracks the localizer/GS...I just changed how the switches functioned.  My AP seems to work just fine, except that sometimes it doesn't grab the glideslope properly...usually when I've just loaded a saved flight.


Just to be certain that my issue is clearly stated:

If I hand-fly the intercept (LOC and GS) and *then* engage the Auto/GS mode once established on both the LOC and the GS, it *holds* them just fine.

My only issue is that the AP steadfastly refuses to INTERCEPT and CAPTURE the LOC and GS when both are approached in a "normal" way- 10-20 degree LOC intercept angle and well below the GS.

Thanks-

Title: Re: AUTOPILOT-the only thread please
Post by Matt2218 on Dec 14th, 2009 at 12:25am
I hear you loud and clear on that.

Regarding what Richard said, I always make sure I'm below MLW so that may explain why I've been able to capture the localizer ok.  

Even when I get the localizer, I'm still hit or miss on the glideslope...it seems like if I do anything out of the ordinary the AP forgets what it's supposed to do.

Fortunately hand-flying this aircraft is very doable :)

Title: Re: AUTOPILOT-the only thread please
Post by Launchbury on Dec 14th, 2009 at 2:09am

Matt2218 wrote on Dec 14th, 2009 at 12:25am:


Fortunately hand-flying this aircraft is very doable :)


Yeah it is!  :D  Only problem, though, is I'm betting it's a real handful on VATSIM.

Title: Re: AUTOPILOT-the only thread please
Post by cyberstudio on Dec 15th, 2009 at 9:57pm
Help! :S

When enabled, the autopilot in the 727 should keep the pitch angle. My 727 can't do that. Why? A bug?

Title: Re: AUTOPILOT-the only thread please
Post by cyberstudio on Dec 17th, 2009 at 5:18pm
Please guys... help :-?

Title: Re: AUTOPILOT-the only thread please
Post by Matt2218 on Dec 17th, 2009 at 7:01pm
Cyberstudio;

I have made some mods to the xml autopilot gauge that might solve your problem with pitch control; if you have a spare email address that you don't mind posting I can send it to you.

Matt

Title: Re: AUTOPILOT-the only thread please
Post by cyberstudio on Dec 17th, 2009 at 7:37pm
Hi Matt!

aeryxs@gmail.com

thanks a lot!!  :D

Title: Re: AUTOPILOT-the only thread please
Post by HoggyDog on Dec 18th, 2009 at 8:13pm

Matt2218 wrote on Dec 14th, 2009 at 12:25am:

Regarding what Richard said, I always make sure I'm below MLW so that may explain why I've been able to capture the localizer ok.  

Even when I get the localizer, I'm still hit or miss on the glideslope...it seems like if I do anything out of the ordinary the AP forgets what it's supposed to do.


Please, will someone explain to me what the aircraft weight (at approach time) can possibly have to do with the inability of the AP to properly capture and fly an ILS? Even the old Sperry AP in this aircraft should be capable of intercepting and flying an ILS down to DH or lower irrespective of aircraft weight!

This old airplane does not have a FMS, fuel-burn calculators or any other sophisticated automation. Just an old Sperry autopilot and steam gauges. There is no way that this autopilot even "knows" what the aircraft weight is at any given point in a flight. How, then, could aircraft weight at any point in any flight have any effect whatsoever on autopilot operation?

Imagine taking off in a full-gross-weight 727-200, losing an engine, deciding to immediately land back at the departure airport and finding out that your AP doesn't work except at certain weights... the concept is absurd.

This AP has only 2 axes: pitch and roll. These are aerodynamic parameters, measured by spinning gyros, not weight parameters. Yes, I know that pitch angle to maintain any particular vertical flight path (level, climb, descent) at any given speed is dependent on weight, but the variations are small, fractions of degrees of pitch to 2-3 degrees or so, and even more telling, THAT IS COMPLETELY BESIDE THE POINT!

In approach mode (Auto/GS), this AP should be able to "see" the ILS needles come alive and anticipate (based on intercept angles, simple basic math) how soon BEFORE the actual intercept point it needs to begin turning or pitching to capture the correct path... mine never anticipates... it waits until the intercept point has come and gone, then makes gross overcorrections back toward the LOC and/or GS.

I submitted a ticket on this, and the response was "we do not experience this problem." This is not helpful. I am doing everything "by the book" as far as AP setup and aircraft configuration are concerned. I have read all 3 manuals cover-to-cover several times, and I am following the procedures there TO THE LETTER. Based on postings here and elsewhere, I am not the only one experiencing autopilot "wonkiness" on ILS's.

Since CS apparently won't or can't help, I am hoping that someone here on the forum can help me to understand what I am doing wrong, or at least what needs to be done to make the AP capture and fly an ILS. However, I am BAFFLED by the references to aircraft landing weight in connection with autopilot function.

Please, someone help me understand what aircraft weight has to do with AP function. This (or any other approach-capable) AP should capture and fly the needles much better than I can AT ANY AIRCRAFT WEIGHT INCLUDING 5000 LBS OVER GROSS TAKEOFF WEIGHT!

Thanks in advance to anyone who can help me to understand the bizarre concept of aircraft weight preventing correct AP function.

Title: Re: AUTOPILOT-the only thread please
Post by HoggyDog on Dec 18th, 2009 at 10:39pm

Matt2218 wrote on Dec 17th, 2009 at 7:01pm:

I have made some mods to the xml autopilot gauge that might solve your problem with pitch control; if you have a spare email address that you don't mind posting I can send it to you.


Matt, I would like to try your mods too- I have a ticket in regarding the failure of the AP to hold pitch when engaged after takeoff, but meanwhile if you have fixed it I would love to try your fix!

hoggydog@bellsouth.net

Thanks!

Title: Re: AUTOPILOT-the only thread please
Post by Matt2218 on Dec 19th, 2009 at 2:19am
On its way.  Let me know how you make out.

Cyberstudio - I emailed you...pls let me know if you didn't get it.

Title: Re: AUTOPILOT-the only thread please
Post by Richard Portier on Dec 19th, 2009 at 2:07pm
HoggyDog,

You wrote "Please, someone help me understand what aircraft weight has to do with AP function. This (or any other approach-capable) AP should capture and fly the needles much better than I can AT ANY AIRCRAFT WEIGHT INCLUDING 5000 LBS OVER GROSS TAKEOFF WEIGHT!"

May be I'm wrong but consider the weight like a consequence not the cause.
For me the problem is in amount, located in some flags... Where ? that is the question.

Actually I am trying some adjustements (one by one, it's a long process) in air and cfg files parameters. I'm not a guru. I have an empiric approach. So...!

Also the issue is perhaps in an other place because some pilots have this problem, some other have not !?

Regards.

Richard

Title: Re: AUTOPILOT-the only thread please
Post by HoggyDog on Dec 19th, 2009 at 5:59pm

Richard Portier wrote on Dec 19th, 2009 at 2:07pm:
May be I'm wrong but consider the weight like a consequence not the cause. For me the problem is in amount, located in some flags... Where ? that is the question.

Actually I am trying some adjustements (one by one, it's a long process) in air and cfg files parameters. I'm not a guru. I have an empiric approach. So...!

Also the issue is perhaps in an other place because some pilots have this problem, some other have not !?


In their response to my ticket on this issue, CS said that I should check aircraft speed, configuration and WEIGHT. They cited these 3 factors in the context of any one of them causing the AP not to be able to capture an ILS.

I can see how SPEED, if too high, would make the AP lag behind the ILS needle indications- simply because they come and go so quickly if you are flying toward the LOC and/or GS at an excessive speed... the AP just can't make adjustments that fast. I get that. I can even understand how flaps configuration could affect the AP because you can't fly the airplane at correct approach speeds without flaps & slats. However, this is only a peripheral connection; the REAL culprit would still be SPEED, because the old Sperry AP neither "knows" nor cares how much flap you have out. If you could fly the airplane on approach at 125KIAS without flaps, the AP should be FINE with that. So "configuration" would be only an indirect factor preventing proper AP function- only because proper config enables slow-enough airspeed.

I find it difficult to believe that CS or any other sim-aircraft developer of their caliber would program in a clearly-irrelevant "weight" parameter in the AUTOPILOT operation of an airplane that has ZERO automation such as FMS. Without FMS or similar functionality, the AP simply has no way of "knowing" aircraft weight at any given point in time- so why would excessive WEIGHT play any part in causing the AP to fail to capture and fly an ILS?

I'm just baffled by CS's suggestion that I should check approach WEIGHT as a possible cause for the AP failure to capture LOC and GS.
Likewise, I'm baffled by those who said here (above somewhere) that the AP works for them on ILS's with an empty airplane but not when loaded. It's just nonsensical to me.

You might as well say that the AP in this airplane only works well if the windshield wipers are turned on. That's how absurd and irrelevant "weight" seems to me as a possible cause of AP failure.

That's why I asked for help in understanding what weight can possibly have to do with AP operation on approaches in this steam-gauge, no-FMS airplane.

Title: Re: AUTOPILOT-the only thread please
Post by HoggyDog on Dec 19th, 2009 at 6:15pm

Richard Portier wrote on Dec 19th, 2009 at 2:07pm:
Also the issue is perhaps in an other place because some pilots have this problem, some other have not !?


I wonder how safe it would be for me to re-install the downloaded CS files (3 of them: the basic 727-100, the 727-200 and the freighters) over the top of my existing installation?

If some pilots are NOT experiencing this problem, there is obviously some difference between their installations and mine (and the many others who ARE having the problem.)

Or, is it possible that those of us having the problem have somehow installed a different VERSION of the package(s) than those who do not have the problem?

I purchased & downloaded my CS-727's on December 5, 2009. I installed them in the order 727-100, then 727-200, then the freighters. I have not installed any SP's or patches because the CS website indicates that the download installation files already incorporate the latest versions with all patches applied, and no SP's have been announced since then.

Can someone who is not experiencing AP failure to capture ILS's with normally-loaded airplanes please post when they installed their package, which of the 3 packages they installed, in what order, and whether or not they have applied any SP's since installation?

I wish I knew how to determine what "version" my installation is, but other than the name of the installation executables, I can't find any version info.

Title: Re: AUTOPILOT-the only thread please
Post by Matt2218 on Dec 19th, 2009 at 10:24pm
I think it would be perfectly safe to re-run the executables...or you could uninstall/reinstall.

I wonder if it could be an FSUIPC version issue?  Grabbing at straws here...maybe check which version of FSUIPC you have installed (I think it's in the 'modules' folder in FSX) and see if it is the most recent one.

FWIW my C-130 is a bit lazy grabbing the localizer...sometimes I have to do the off/on routine with track mode.

Title: Re: AUTOPILOT-the only thread please
Post by TacomaSailor on Dec 20th, 2009 at 12:16am
I am periodically having many of the problems previously described during a thread that covers 10 months.  But I see no solution to any of them:

1)  AP NAVLOC ON  VOR captured (green light is ON) flying properly to the heading - ALT HOLD & ELEV engagement switch is OFF is off but AC climbs at 1000'/minute even with maximum down yoke/down trim.  Turn off AP and I immediately regain elevator control.    As soon as I engage AP-NAV LOC the AC starts climbing

2) AC & AP are working perfectly - AC is stable in NAV-LOC with ALT HOLD on.  FL 20 at Mach .71  - suddenly the AC starts falling from sky at 5,000 fpm while maintining Mach.71 and N1 at ~85%.   IAS starts to drop rapidly, I push over, increase the throttle to 99% but the IAS continues to drop and the Vertical Airspeed does not change.  If I push over into a near vertical dive the flight ends with a an Overspeed/Overstress and IAS of less than 100 kts just before breakup.  

When this happens at 9,000' and 225 kts there is no way to recover.  The AC pancakes at a vertical speed of 6000 fpm and IAS of 0 kts with N1 at 100%.

3) AC is on AP (NavLoc/Alt Hold) and stable at Mach .71 - starts going up and down 1000 fpm in a slow fashion - throttles don't move, control surfaces don't move but plane climbs then descends.  Turning off AP immediately stabilizes AC.

4) Level Stable flight at 15,000  Nav1 captures VOR - I hear the correct  Morse Code - AP on NavLoc - green light on dash - Aileron and Elevator engaged in AP   The DME is showing the correct distance and the HSI is lined up with the correct course selected.  BUT - - AC flys at right angels or even away from VOR.  

Most of the time (over 80% of flight hours) the AP works just as it should.  :D

I know it's an old AP but is that the way it is supposed to work?

Title: Re: AUTOPILOT-the only thread please
Post by HoggyDog on Dec 20th, 2009 at 7:59pm

HoggyDog wrote on Dec 20th, 2009 at 7:35pm:

TacomaSailor wrote on Dec 20th, 2009 at 12:16am:
1)  AP NAVLOC ON  VOR captured (green light is ON) flying properly to the heading - ALT HOLD & ELEV engagement switch is OFF is off but AC climbs at 1000'/minute even with maximum down yoke/down trim.  Turn off AP and I immediately regain elevator control.    As soon as I engage AP-NAV LOC the AC starts climbing


For lack of a better term, this is what I call the "pitch runaway" syndrome of this AP, i.e. AP fails to hold pitch properly. I have submitted a ticket on this and it has been "forwarded to the development team for consideration." So the good news is, CS is able to duplicate the problem and is aware of it.


TacomaSailor wrote on Dec 20th, 2009 at 12:16am:
2) AC & AP are working perfectly - AC is stable in NAV-LOC with ALT HOLD on.  FL 20 at Mach .71  - suddenly the AC starts falling from sky at 5,000 fpm while maintining Mach.71 and N1 at ~85%.   IAS starts to drop rapidly, I push over, increase the throttle to 99% but the IAS continues to drop and the Vertical Airspeed does not change.  If I push over into a near vertical dive the flight ends with a an Overspeed/Overstress and IAS of less than 100 kts just before breakup.


This sounds like a combination of three well-known and previously-discussed issues:

1. Triple flameout due to improper crossfeed setup (see JETPILOT's informative response to this nasty inflight surprise elsewhere in the forums). It is conceivable that you could still show a "normal" N1 speed due to windmilling of the flamed-out engines as you plummet to the ground with no power; and

2. The VSI is inaccurate. Matt2218 has addressed this in another thread in this forum; and

3. The aerodynamic modeling of this airplane is WAY off, such that power (throttle) has TOO MUCH impact on speed, and pitch has TOO LITTLE impact on aircraft speed. Again, our hero (and RL 727 pilot) JETPILOT has discussed this long-standing issue elsewhere (possibly here, possibly on AVSIM). The exact problem he discussed was that it is impossible to descend the airplane with throttles correctly set at idle no matter how large the rate of descent is- you have to carry some power in the descent to maintain airspeed even on a "clean" (no flaps, spoilers or gear out) airplane- which is just silly. The 727 is a fast, "slick" airplane and should maintain airspeed during a descent at idle throttle with descent rates of anything over 1000 fpm.


TacomaSailor wrote on Dec 20th, 2009 at 12:16am:

3) AC is on AP (NavLoc/Alt Hold) and stable at Mach .71 - starts going up and down 1000 fpm in a slow fashion - throttles don't move, control surfaces don't move but plane climbs then descends.  Turning off AP immediately stabilizes AC.


This is what my AP does as it tries to capture a GS in Auto/GS mode AND when engaged during the first segment climb after takeoff- it's the AP "pitch runaway" issue, Part Deux. The bottom line here is that the AP pitch control simply doesn't work, period. Hopefully, CS will fix this sooner rather than later.


TacomaSailor wrote on Dec 20th, 2009 at 12:16am:

4) Level Stable flight at 15,000  Nav1 captures VOR - I hear the correct  Morse Code - AP on NavLoc - green light on dash - Aileron and Elevator engaged in AP   The DME is showing the correct distance and the HSI is lined up with the correct course selected.  BUT - - AC flys at right angels or even away from VOR.


Haven't experienced this one (yet). If you're sure your course needle was set correctly (it can be confusing, depending on whether you intend to fly TO or FROM the VOR) then this is just another example of autopilot "wonkiness" in the CS 727 (FSX).


TacomaSailor wrote on Dec 20th, 2009 at 12:16am:

Most of the time (over 80% of flight hours) the AP works just as it should.  :D


I wish I could say the same. My AP has ***NEVER*** captured a LOC or GS without first delaying the roll or pitch toward the correct path until after it has passed and then overcontrolling the airplane after the correct path has come and gone, resulting in endless zigzagging and porpoising... and a crash if I don't disconnect it and try to salvage the approach by hand... and it has ***NEVER*** held pitch on initial engagement after takeoff.

[quote author=Ta link=1234458523/45#54 date=1261268160]I know it's an old AP but is that the way it is supposed to work?


Um, no. This is the longest and most consistent thread on the entire 727 Forum, even after you disregard some of the posts wanting to know where the alt-preselect or autothrottle-enable switches are (the airplane doesn't have those.) It is CLEAR from the many AP issues discussed here over the past 10 months that CS needs to completely re-work the AP "logic" and functionality in this airplane. Hopefully, they will do so soon. Please, CS, move this to the top of your list and FIX IT!

Title: Re: AUTOPILOT-the only thread please
Post by TacomaSailor on Dec 21st, 2009 at 3:24am
TacomaSailor wrote on Yesterday at 4:16pm:
2) AC & AP are working perfectly - AC is stable in NAV-LOC with ALT HOLD on.  FL 20 at Mach .71  - suddenly the AC starts falling from sky at 5,000 fpm while maintining Mach.71 and N1 at ~85%.   IAS starts to drop rapidly, I push over, increase the throttle to 99% but the IAS continues to drop and the Vertical Airspeed does not change.  If I push over into a near vertical dive the flight ends with a an Overspeed/Overstress and IAS of less than 100 kts just before breakup.

:D :D :D

NOW I UNDERSTAND!! - It is a DEEP STALL and Captain Sim modeled it perfectly - as far as I can tell from my limited experience.

In test flying at 12,000' I found that the 727 will go into a deep stall at somewhere around 138 - 140 knots at a AoA of 7 degrees. Once in the deep stall the vertical airspeed quickly reaches 6,000 fpm downward. If recovery is not accomplished within 10 seconds of stick shaker it is almost impossible to recover. However, if at stick shaker onset I push the yoke and increase the power (AFTER the nose drops!) I can recover with the loss of about 4,000 feet. The AC begins to have a positive climb rate at an IAS of around 200 knots.

I'm sure many of you know about deep stalls but since it is a phenomena pretty much restricted to T-Tails it is something I had never experienced or read about.

At a high AoA the horizontal portion of the T-Tail becomes blanketed by the disturbed air from the wing. When the wing stalls - the elevator has little authority to force the nose down. As the stall deepens the elevator looses all authority and becomes useless. The AoA (documented in real life) continues to increase -OR- the AC settles into a wings level nose level attitude with a very high vertical air speed. The AC then pancakes in a near level vertical drop. Well documented on the WEB (Wiki is a good start) and fun to read about.

Now that I understand it I see Captain Sim did a great job of building the proper flight dynamics.

This happens when I fly the 727 on AP and for whatever reason the AoA increases with a drop in IAS. If I am not paying attention and don't hear the stick shaker - then it quickly becomes unrecoverable.

SO - the question becomes - WHY when the AC has been under control of the AP in level stable flight for many minutes, or even hours, does the AoA suddenly increase and the IAS drop? It seems to occur in AltHold and for some reason the throttles slowly retard - thus forcing the AP to trim for pitch up and allows IAS to decrease.

I KNOW - the AP does not control the throttles but at Mach .71 changing the AoA by 5 degrees should not get the AC to Vs.  I need to find a flight envelop diagram for the 727-100 to determine the critical AoA at Mach .71/FL20 - MAYBE it is that sensitive.  Although I thought Vno was around Mach .85.

Good Job on the Deep Stall - Captain Sim!!

this is a copy (with more AP details) of a reply I added to the AVSIM 727 Opinion Thread

Title: Re: AUTOPILOT-the only thread please
Post by HoggyDog on Dec 21st, 2009 at 6:41pm

TacomaSailor wrote on Dec 21st, 2009 at 3:24am:
NOW I UNDERSTAND!! - It is a DEEP STALL and Captain Sim modeled it perfectly - as far as I can tell from my limited experience.
[...]
I'm sure many of you know about deep stalls but since it is a phenomena pretty much restricted to T-Tails it is something I had never experienced or read about.


Back in the Dark Ages (around the time that early 727's were rolling off the Boeing assembly line) I remember a lively "hangar talk" session about the new Piper Arrows being given T-Tails for no reason other than "visual style" and/or "ramp appeal." Somehow, Piper's Marketing people had prevailed over the aerodynamicists and engineers and convinced Management that the airplane would sell better if it looked more like a jet.

The conclusion of the assembled sages that day was that Piper had shot itself in the foot, and that the adverse aerodynamic characteristics of T-Tails (elevator blanking) at rotation, in the flare and (as you have discovered with the 727) in "slow flight" when level would basically "kill" the Arrow as a marketable airplane. As evidence, they discussed the elevator blanking so painfully obvious in Piper's attempt to unseat the Cessna 150/152 as the most widely-used primary trainer: the Tomahawk, which also had a T-Tail purely for misguided aesthetic reasons and whose entire empennage would shake visibly and audibly while practicing stalls. I turned around to look at it once while it was shaking and flapping around at the onset of a stall, and I immediately released back pressure, resumed normal flight, returned SLOWLY AND GENTLY to the airport and refused to ever fly a Tomahawk again. It's the only time in my long and mostly-routine flying career that I was AFRAID of what was happening and genuinely fearful that I would not make it back alive.

Turns out the sages were right about the T-Tail Arrow- it wasn't long before poor sales moved Piper to have the same epiphany- they put the horizontal stab back where it came from, i.e. where the engineers said it should be. Also, on the used airplane market, the T-Tails are generally the cheapest and least-desirable of all the Arrows, other factors being equal.

Of course, the T-Tails on 727's, DC-9's (etc. etc.) were put there due to engine placement, not aesthetics, but the result is that elevator blanking at high AoA is a very real phenomenon in pretty much ANY T-Tail airplane, large or small. That's why the "normal configuration" for horizontal stabs has them mounted on or very close to the fuselage.

The only part of your post that I'm having any difficulty understanding is where you appear to say that you are reading Mach .71 and 140 KIAS simultaneously at 12,000 ft MSL. Just "don't seem right" to me.  :o

Also, I was under the impression that ALL autopilots would "kick off" at the onset of the stick shaker. I have no personal RL experience with the 727's Sperry, but I thought that this was a certification requirement. Many large airplanes even have "stick pushers" that take affirmative action to cure an incipient stall- I wonder if the 727 had a stick pusher as well as a stick shaker?

Title: Re: AUTOPILOT-the only thread please
Post by TacomaSailor on Dec 21st, 2009 at 10:22pm
As far as I can tell - activation of the stick pusher does not turn off the 727 Sperry AP in my 727.  

I think I have determined two causes of the excursion into a deep stall.   One is pilot error - the other is ???

Flying below 10000' at about 190 knots using the AP in ALT HOLD and HeadingSelect.  Change the heading bug for a 90 degree turn.  The AC enters a standard rate turn.  If the turn continues long enough - the airspeed keeps dropping if I don't increase throttle - eventually drops below Vs with AoA (I did ask it to keep a set altitude) ever increasing.   This is just bad piloting.

I have done lot's of testing at FL32 and find that I can enter a DEEP STALL if the AoA exceeds 16 degrees and Mach drops below .48 - now why does it do that?

I think it happens when I have a GPS on the 2nd monitor.  I am making keyed inputs into the GPS, e.g. new VOR, and the FSX or 727 program sees those as inputs to the AP or throttles.   For example I was typing in the new VOR and the AP disconnected and the throttles rolled back from 80% to 20% - I let the problem progress and soon the plane was pitched up at 16.8 degrees, IAS was 114. MACH was .45 and vertical speed rapidly approached -10,000.  

All this occurred when I typed NID into what I thought was the GPS but  it acted like the focus was still on the VC so the NID was taken as input to the ???

While testing the Deep Stall I just saw IAS=265, MACH=.58, AoA 1 degree up and VSI=-6000.   This was during recovery while I was trying to bring the nose up without overstressing the plane.  

So - I think my Mach.71/IAS 140 must have been during the recovery - before I understood the problem.

However,  the 727 VC gets in a situation where the MACH and/or the IAS jumps suddenly either UP or DOWN and often not in synch.  The ADI also goes from horizontal to vertical (on it's side as if OFF) at times and stays like that for many seconds - then spontaneously reverts to a normal horizontal display.

The problem comes and goes but gets progressively more frequent - the only way to stop the problem is save the flight, exit and restart FSX.

My last observation is that the AP does capture the VOR in NAV LOC and does EVENTUALLY get on track.  I have run a number of tests where I selected NAV LOC while approaching the desired radial at an angle of 10 or so degrees and three dots off the track.  The SPERRY AP in my 727 will overshoot the desired radial and then oscillate back and forth for several minutes before settling down on the course.  The oscillations can take it up to 3 dots past the desired track.  

But, if I leave it alone, it always gets on track after three or four minutes.  

Title: Re: AUTOPILOT-the only thread please
Post by MercuryOneOne on Oct 21st, 2010 at 2:13am
Here is a link to my youtube video tutorial on how to use the 727 autopilot for an ILS landing. http://www.youtube.com/watch?v=fy3utBqi7-4

I hope this is helpful!

Title: How do I work the AP?
Post by IflyGr8 on Feb 2nd, 2010 at 3:15am
Hi all,
I've had the 727 for a while, and i don't know how to get the AutoPilot workoing, and I've been trying to use it, but i can't get it.  so if you could plese help me, or tell me how.

Thanks

Title: Re: How do I work the AP?
Post by Howell on Feb 2nd, 2010 at 7:52pm
Well . . . this could be long which I hate, so I will keep this short and hope it leads you down the bunny trail.

 There are two AP stations on the 727
1) Is called "Autopilot Panel"  which sits bellow the throttles and radio / Nav radio stack.

2) is called "FLIGHT DIRECTOR CONTROLS" which sits above the throttles on the left and right.

 To work the AP . . .
Once lined up for T/O I assume that your heading indicator is lined up with the runway or the heading that ATC issued.  I would then go to the  "Autopilot Panel" panel and make sure your heading selector is up to activate and the knob above is on "B".  On the "FLIGHT DIRECTOR CONTROLS" panel turn the knob to HDG. Make sure your Nav radio is tuned to the first VOR.
 Once airborne and in good steady rate of climb,  flick the two switches on "Autopilot Panel" called "ELV" and I forget name, but there side-by-side, but go ahead and flick up to engage.  Once your vectored to your first VOR or ADF and your "Radio Magnetic Indicator (RMI) is reading your signal, turn both knobs from "Autopilot Panel" and "FLIGHT DIRECTOR CONTROLS" to LOC/VOR and turn off the HDG on your "Autopilot Panel" and your are set on AP.

  I hope this helps!

Title: Re: How do I work the AP?
Post by Berlopez on Feb 15th, 2010 at 12:15pm
Sorry to bud in here...

How can I do an ILS landing on the 727-100? How can I identify the NAV2 radio to tune in the Rwy. ILS frequency,before I click G/S.Last night I attem,pted by tuning on the second form the top radio,thinking that is the NAV2,But upon intercept It turned and dived!?...

Title: Re: How do I work the AP?
Post by Markoz on Feb 15th, 2010 at 2:00pm
Hi Berlopez.

Firstly. I'm using the 727 v2.3 without any mods.

I have found that the trick to catch the ILS and GS is to come into it at about 10 degrees or less than the Localizer heading and below the Glide Slope.

I use HDG SEL and ALT HOLD and I have the Mode Selector Knob on AUTO G/S as I'm coming in.
My altitude is at about 3800' AGL at around 11nm from the airport.
When I get close to the Localizer the HDG SEL disengages on its own accord and starts turning onto it.
Then as the Glide Slope is just about at the centre of the ADI. I manually disengage the ALT HOLD. This allows the plane to follow the Localizer and GS to the runway.
As it gets close to the Runway Threshold I have to turn the Autopilot off or it will start climbing again just prior to landing (it's as if the GS starts to go up again at that point).

Hope this helps.

Mark

Title: Re: How do I work the AP?
Post by MercuryOneOne on Oct 21st, 2010 at 1:56am
Reply for Berlopez -
I have posted a 2 part video on youtube on how to use the Captain Sim 727 autopilot. You can view it here: http://www.youtube.com/watch?v=fy3utBqi7-4

Title: Re: AUTOPILOT-the only thread please
Post by LOU on Oct 28th, 2010 at 2:50am
This is an old post from page #2 Maybe it will help...

Autopilot operations on the CS-727.

I have Ver 2.4.

Just flew a bunch of ILS autopilot approaches to see how the CS-727 works. It is remarkable how this software simulates the real 727.

The key to a autopilot approach is not to hurry the poor autopilot. Remember this is 1950's state-of-the-art stuff so you can't expect 757, 767, or Airbus navigation or electronics. In the real plane you need to be set-up for the approach long before intercept...no different here!

Get all the radios set to the correct frequencies and set the course on the HDI to the ILS inbound course. You can get the correct freq. from the MAP drop-down. Just mouse over the ILS for the runway you plan to land on and the ILS information will appear.

As you fly in the traffic pattern have the autopilot in MANUAL or HEADING SELECT with ALTITUDE HOLD engaged. You can steer the plane in heading select and work yourself toward and intercept heading.

Here are some ball park or canned speeds to fly in the pattern:
Landing weight 125,000 to 130,000#
CLEAN - 230 KTS (not less than 200 KTS)
FLAPS 2 - Not more than 230 KTS not less than say 180 KTS
FLAPS 5 -between 180 and 160 KTS
FLAPS 15 around 150 KTS

As you get close to the ILS intercept be at FLAPS 15 and around 150 KTS. This will give you a better degrees per second turn rate thus giving the old autopilot a better chance of success. (the faster you go the slower the turn rate for a given bank angle)

You can select AUTO-G/S anytime during your vectoring for the intercept. The autopilot will remain in HEADING SELECT until LOC intercept.
You must remain BELOW the G/S and intercept the LOC first.

I set up the plane on an intercept heading of around 30 degrees to the localizer and on the initial approach altitude for the ILS selected and about 10 miles from the airport.

I set up the autopilot & F/D in altitude hold and heading select.

I select G/S AUTO on both the autopilot and the F/D. I am flying at 150 KTS with flaps 15 which is a normal setting for this phase of the approach.

Give the autopilot a chance to do it's thing by not rushing the approach.

As the LOC comes alive, the autopilot and F/D will captured the LOC and intercept. The heading select will trip off.  With the LOC captured and the plane at 150 KTS and flaps 15 degrees I am now trucking towards the runway. As the G/S comes alive select gear down. One dot to G/S intercept select flaps 30 degrees and as the plane pitches down at G/S intercept adjust power to maintain speed. For these approaches I set the fuel load to 20,000 # and I used around 125 KTS on final.

Note on the F/D... To get "all angle capture" by the F/D you must first select HEADING SELECT and be in that mode for a few seconds before selecting G/S AUTO. The F/D will remain in heading select and can be controlled with the heading knob up until capture of the LOC. If you do not do this heading select first and go directly to G/S AUTO the F/D will program a 45 degree intercept. Not a big deal, but this will give you the option of guiding the plane to an intercept heading during vectoring.

Take note of the approach progress display group of lights on the instrument panel. They show the modes of the autopilot and the F/D as they go through the various arm & capture modes.

Make smooth and slow power changes and try to hold a constant speed. Every speed change will result in a pitch change and thus a trim change and the approach becomes unstable. I use FUEL FLOW to set power. At 30 degrees flap at this weight around 2,000 to 2,500 FF should be close. Adjust smoothly to stay on speed.

The 727 is not an auto land plane so you must disconnect before touchdown.  

MANUAL G/S was only used:
When above the glide slope or on an extended (long) approach.

Once the ILS is captured by the autopilot a timer starts in the autopilot. As the aircraft gets closer to the runway the LOC and G/S get more sensitive. Boeing designed the glide slope to begin desensitization as the plane would get closer to the runway. In the 727-100 this was based on time. (the 727-200 used the radar altimeter - much better! Did not need to use this procedure.)

So, if you are on an extended (long) final and you have intercepted the ILS at a higher altitude the G/S would need to be re-sensitized during the approach. Here is how you do this: While in AUTO G/S and on LOC and G/S, you select a non radio mode - HEADING SELECT, then select MANUAL G/S quickly by pushing down on the switch and move to MANUAL G/S. Folks, this is way too detailed for this simulator. Just don't fly too long a final and intercept at a higher altitude. You can fly a 50 mile LOC (done sometines in KLAX or KLAS) just don't select AUTO G/S until 7 or 8 miles out.

I hope this information helps. It's a bit technical, but simmers like myself enjoy the detail. I find this CS-727 to be a blast and a lot of fond memories of the old plane which was always fun to fly.

Remember this is a "game" not a multi-million dollar simulator. I think it's a great simulation and it flys pretty much like the real thing which was not CAT-II. Give it a try and don't rush the approach and it will do a good job.

Lou

Title: Re: AUTOPILOT-the only thread please
Post by CoolP on Oct 28th, 2010 at 10:40am
Great post, Lou. Page #2 therefor was a diamond.

Title: Re: AUTOPILOT-the only thread please
Post by Captain Sim 2 on Oct 28th, 2010 at 11:23am
Yes indeed, that is why it was posted to KB into 'Tips and Tricks' category - Autopilot operations on the CS-727 (by LOU), KB# 6061.

Title: Re: AUTOPILOT-the only thread please
Post by MatzeH84 on Oct 28th, 2010 at 11:25pm
Question on that- first to say I own a boxed version which is 2.3.
On the APD there seem to be no armed conditions- when I switch to NAV/LOC for example, the indicator turns green immediately, even if miles and miles away from the point where I'd cross the selected radial. The F/D turns only to amber when the A/P is on manual while NAV/LOC or other mode selected on the F/D. Is this a 2.3 issue? Hoping for a 2.4 for the another company box.. regards

Title: Re: AUTOPILOT-the only thread please
Post by simbiosi on Oct 29th, 2010 at 10:02am
For my experience there is no way to capture a radial  To or from a VOR, the only way to capture the radial is to engage the FD auto GS and it will follow but not really straight and doing some zigzag.
I have also a problem with the trim setting but maybe is my lacks of knowledge, when I set trim  the aircraft dosen't  keep my input after scroll it goes back.
Also the FD attitude dosen't work.

Title: Re: AUTOPILOT-the only thread please
Post by MatzeH84 on Oct 30th, 2010 at 7:43pm
Nah.. with the autopilot-mod the AP intercepts and holds the radials of a VOR like a charm. But there are no amber (armed) conditions.
Say I fly with HDG and ALT HOLD and like to intercept a radial of a VOR station tuned on NAV1. So I select VOR/LOC on both FD and AP, and the AP indicators immediately turn green (they should only do when capturing the radial!). Also the HDG mode is not cancelled when getting in capturing range, this has to be done manually (same with glideslope intercept when on ALT HOLD).

Title: Re: AUTOPILOT-the only thread please
Post by checharin84 on Nov 6th, 2010 at 11:17pm
hi there! i just bought this plane! and is awesome! but I just got a problem, in the first flight that i made, it was ok! but today i just went to fly! and after a random period of time! when i am taxiing, or just after take off, the FD, AP and NAV stop working! i just cant change mode select on FD, the plane doesn´t follow HDG, or ALT hold, and can´t change NAV FREQ, is something that i am missing??? i reinstalled it and didn`t changed,  also i was having a sound problem but i just reload the plane and i can hear everything.  hope that someone know something about this!. Greetings.

Title: Re: AUTOPILOT-the only thread please
Post by Markoz on Nov 7th, 2010 at 1:54am

CesarSMX wrote on Nov 6th, 2010 at 11:17pm:
hi there! i just bought this plane! and is awesome! but I just got a problem, in the first flight that i made, it was ok! but today i just went to fly! and after a random period of time! when i am taxiing, or just after take off, the FD, AP and NAV stop working! i just cant change mode select on FD, the plane doesn´t follow HDG, or ALT hold, and can´t change NAV FREQ, is something that i am missing??? i reinstalled it and didn`t changed,  also i was having a sound problem but i just reload the plane and i can hear everything.  hope that someone know something about this!. Greetings.


You lost electrical power. The fix is to add electric_always_available=1 in the aircraft.cfg (open with windows notepad) like this:

[electrical]
electric_always_available=1
max_battery_voltage = 24.0
generator_alternator_voltage = 30.0
max_generator_alternator_amps = 400.0

It seems like some switch or button isn't in its correct position. I have turned that OFF (electric_always_available=0) in my aircraft.cfg and I no longer lose power.

If you have a registered version of FSUIPC you can have the power set to always be there too.


I hope this helps.

Mark

Title: Re: AUTOPILOT-the only thread please
Post by checharin84 on Nov 7th, 2010 at 6:11am
Thanks Markoz. that fixed it, Now I just need to check my OC, lol.  :o


Title: Re: AUTOPILOT-the only thread please
Post by checharin84 on Nov 13th, 2010 at 3:40am

CesarSMX wrote on Nov 7th, 2010 at 6:11am:
Thanks Markoz. that fixed it, Now I just need to check my OC, lol.  :o




ohh no! everything was fine until today!! even with "electric_always_available = 1", I am having that problem again!, i just turn on APU, and problem solved, I check batt gauge and  voltaje and amps are ok,  and yes i double check aircraft.cfg!  what is going on now???  :o

Title: Re: AUTOPILOT-the only thread please
Post by LOU on Nov 13th, 2010 at 8:33pm
checharin84,

This simulator is a lot like the real plane.

* Make sure all the engines have fuel - look at the x-feed valves and the fuel level.
* Make sure the generators are connected to the load bus and check essential power on an operating generator.
* Make sure the battery switch is on as well.

I have never had the problem you describe on any of the CS planes and I don't use FSUIPC, just the CS profile.

I hope you can fix your problem.

Lou

Title: Re: AUTOPILOT-the only thread please
Post by checharin84 on Nov 14th, 2010 at 7:01pm

LOU wrote on Nov 13th, 2010 at 8:33pm:
checharin84,

This simulator is a lot like the real plane.

* Make sure all the engines have fuel - look at the x-feed valves and the fuel level.
* Make sure the generators are connected to the load bus and check essential power on an operating generator.
* Make sure the battery switch is on as well.

I have never had the problem you describe on any of the CS planes and I don't use FSUIPC, just the CS profile.

I hope you can fix your problem.

Lou



Hi there! i already check that! I will keep testing it! and when I get the disconnection I will take some pics and post them, thnks a lot!!

Title: Re: AUTOPILOT-the only thread please
Post by MatzeH84 on Nov 15th, 2010 at 8:42pm
Check in the FSX key commands if there is a key to turn on the generators. If so, use it, and everything will be fine. If not, define one, use it, and again it should work.

Title: Re: AUTOPILOT-the only thread please
Post by checharin84 on Nov 20th, 2010 at 11:12pm

MatzeH84 wrote on Nov 15th, 2010 at 8:42pm:
Check in the FSX key commands if there is a key to turn on the generators. If so, use it, and everything will be fine. If not, define one, use it, and again it should work.


yep! that was the problem! I dont know why! if I have everything where it need to be. but thanks a lot!

Title: Re: AUTOPILOT-the only thread please
Post by Michael2 on Nov 25th, 2010 at 7:10pm
I recently started using version 2.4, after getting Accelertation, which seems to be needed for the AP to work properly since 2.3.  Previously I was using 2.2 and had no problems with the autopilot.  

Now I find that heading select doesn't trip off on capturing the localiser.  I have to manually turn it off before the localiser intercept, or I just keep going.

Anyone else have this problem?

Title: Re: AUTOPILOT-the only thread please
Post by javiercuellar on Nov 25th, 2010 at 8:17pm

Quote:
I recently started using version 2.4, after getting Accelertation,


I did the same thing  ;)


Quote:
Now I find that heading select doesn't trip off on capturing the localiser.  I have to manually turn it off before the localiser intercept, or I just keep going.


mmm, not for me. What I do:  Alt and Hdg hold both activated. When I'm correctly align to runway, put the knob in Auto GS and HDG will trip off. When GS moves, Alt hold also trips off.

Title: Re: AUTOPILOT-the only thread please
Post by Michael2 on Nov 26th, 2010 at 7:28pm
I've been switching to NAV/LOC with Alt Hold and Heading Select turned on, so as to get on the localiser before the glide slope.  I will try going directly to Auto GS as you suggest. Thanks for the advice.

Title: Re: AUTOPILOT-the only thread please
Post by javiercuellar on Nov 26th, 2010 at 9:08pm
Look this also:  http://www.captainsim.org/yabb2/YaBB.pl?num=1234458523/63#65

Title: Re: AUTOPILOT-the only thread please
Post by Michael2 on Nov 28th, 2010 at 1:04am
Thanks again -- it worked by selecting Auto GS.

Title: Re: AUTOPILOT-the only thread please
Post by Sawydz on Dec 28th, 2010 at 8:36pm
Hello everybody ;)

I have recently purchased this great 727-100, and I have already dealt with few problems with one exception: whenever I try to capture radial to VOR, AP flies never ending S-turns instead of stabilizing flight on selected course. Is there any cure to this behavior?

Grzegorz

Title: Re: AUTOPILOT-the only thread please
Post by audiohavoc on Apr 19th, 2011 at 11:25pm
I have a question about the VOR/LOC mode of the autopilot.  It is my experience that the CS 727 has a difficult time keeping the CDI centered on a radial of a VOR, and it tends to wander a bit when tracking.  I find that I have to use HDG select mode to manually track radials while the A/P is in the VOR/LOC mode.  This is also how I correct for winds.  Is this normal or user error?  I have the CS 727-100 2.4 version installed with the flight model modification, altitude fix, MDA fix, and EPR mod.  I am using this with FSX Acceleration and Windows 7 64.

Title: Re: AUTOPILOT-the only thread please
Post by LOU on Apr 20th, 2011 at 12:36am
audiohavoc
Reply #85 - Today at 12:25am   I have a question about the VOR/LOC mode of the autopilot.  It is my experience that the CS 727 has a difficult time keeping the CDI centered on a radial of a VOR, and it tends to wander a bit when tracking.  I find that I have to use HDG select mode to manually track radials while the A/P is in the VOR/LOC mode.  This is also how I correct for winds.  Is this normal or user error?  I have the CS 727-100 2.4 version installed with the flight model modification, altitude fix, MDA fix, and EPR mod.  I am using this with FSX Acceleration and Windows 7 64.

I just took the 727 for a test trip around the PNW and tried a few VOR intercepts. I gave it a good workout by being close to the VOR - around 30 miles - and at high speed -300 KTS. I put the autopilot on, with heading select and put the plane on an intercept heading for a selected radial. Here is where I find a problem. When on an intercept heading, and the radial not captured (I made sure I was a long way from capture of the radial) when you are in heading select and you put the autopilot in NAV/LOC, the progress display lights for NAV/LOC should be amber (armed for capture) and the heading light should be green. When the computer sees the radial coming alive, the amber should change to green (capture) and heading select should trip to off. This tripping off of HDG is not happening. I believe forum member CoolP has collected this bug in his summary to CS. When I fly the ILS in this plane and set the autopilot on an intercept heading using HDG select and then arm AUTO G/S I get the proper display on the approach progress lights and the HDG does trip off on LOC intercept. Why it acts in a different manner with the VOR is a mystery to me.  :-/

For now, when I see the radial start to come alive, I trip off the heading select and the NAV/LOC part then works fine. The autopilot waits a bit longer than I would to start the turn towards the course, but it does turn and intercept the radial and after a small correction, tracks the radial just fine without any zig zags.

Play with the autopilot a bit more and let this forum know your findings.

Lou

Title: Re: AUTOPILOT-the only thread please
Post by audiohavoc on Apr 20th, 2011 at 12:47am
LOU,

Thanks for the reply, your input is especially helpful and appreciated.  I'll get some more time with the 727 and let you know what I find out.  

Title: Re: AUTOPILOT-the only thread please
Post by audiohavoc on Apr 20th, 2011 at 10:15pm
On my flight today I tried the VOR/LOC mode of the autopilot again, and what I noticed was that it continually overshot the radials causing the airplane to S turn back and forth across the radial. Again I had to resort to manually tracking the radials with HDG mode.  I wonder if this has something to do with using Active Sky Evolution/FSUIPC/FSInn, but I have everything setup to avoid autopilot/weather issues.  Even with this issue, manually tracking the radials works fine and keeps me busy and focused.

Title: Re: AUTOPILOT-the only thread please
Post by CoolP on Apr 21st, 2011 at 1:42am
At which distance are you trying to capture the VOR radials?
Just asking because I've just read about some 35nm+ on another aircraft when using the automated capture. So one could say that below this distance, the manual capture is the better way to use.
Don't chase the needle though!  :D

For me, the 35+ seems a bit too high, but the closer you are, the more upset the old AP gets in my eyes. I'm using ASE too.

Title: Re: AUTOPILOT-the only thread please
Post by audiohavoc on Apr 21st, 2011 at 2:05am
I've tried distances ranging from 30nm to 60nm, unless there is a specified VOR changeover point on the airway.  I manage radial tracking very well with heading select mode, it would just be nice if I could get the autopilot to do it without wandering back and forth.  The strange thing is that when I manually align the radial and have the CDI centered, if I switch off HDG select and let VOR/LOC mode take over, the autopilot immediately deviates off the course.  It then starts wandering again to the left and right, obviously not keeping the CDI centered. :-?

Title: Re: AUTOPILOT-the only thread please
Post by CoolP on Apr 21st, 2011 at 2:14pm
Are you running gyro drift enabled in the FSX realism settings?
Maybe there's an offset between the indicated course and the real one and the AP then goes for the real one (internal FSX value) while you see the deviation on the CDI, because it shows you the offset value. This is just guesswork of mine though.
Would be a typical sim problem of course as real planes would always see the offset only on both systems.

I didn't have the 727 much on VOR to VOR enroute nav, only in the approach or departure phase where I was trying to follow some STAR and SID (which sometimes are described for the "old nav" too). I usually went for manual headings there though because she struggled with the short distances to the VORs when trying to catch the radials. Together with the slow AP turn rate, this really was some "chasing the needle" thing and isn't recommended.
So I just took the CDI to confirm my manual headings, not as primary source of driving the AP.
But your mentioned 30nm to 60nm sound very reasonable of course, she should work fine there.

Have to try this in some later flight I think.

Title: Re: AUTOPILOT-the only thread please
Post by CoolP on Apr 21st, 2011 at 3:19pm
I was just doing some circuits around Brisbane (a bigger town on the Isle of Mark  :D) and can confirm quite some S-turn tendency. It gets better when the speeds go down, so VOR approaches as well as some <250kts SIDs and STARs shouldn't be a big problem, but when going fast, the AP really chases the needle.

The turn rates are slow, so he is doing corrections for quite some time to establish a Course.
I had real world weather on and felt much more confident when using the CDI for verification only, keeping all heading inputs manually (with the bug) or flying the whole thing with the AP off.

As my normal enroute Nav comes from the ("sissy"  :P) Civa INS, I usually don't run into trouble with this issue. The Civa turns are smart and right on time, corrections are done fast and with close to no overshooting.
If I would go VOR to VOR only, I'd tend to use the manual heading bug and get the wind readings from the Civa, to set up the wind correction course.
As said, approaches aren't a problem since the plane is slower and turns better then, so the AP can throw her around way better.  :D
I've tried it around 210 knots, some flaps out and 3000ft when being within 15-8nm from the station. Worked fine. Even landed later, a bit hard though, but the crew remained silent until arriving at the gate where they ran away, screaming for help.
http://img850.imageshack.us/img850/9162/parkingatbrisbane.th.jpg

I remember the 707 to be way better on the VOR to VOR thing, only getting distracted by the cone of silence above the stations, but coming on the right Course pretty fast in between.

Title: Re: AUTOPILOT-the only thread please
Post by audiohavoc on Apr 21st, 2011 at 4:35pm

CoolP wrote on Apr 21st, 2011 at 3:19pm:
I was just doing some circuits around Brisbane (a bigger town on the Isle of Mark  :D) and can confirm quite some S-turn tendency. It gets better when the speeds go down, so VOR approaches as well as some <250kts SIDs and STARs shouldn't be a big problem, but when going fast, the AP really chases the needle.

The turn rates are slow, so he is doing corrections for quite some time to establish a Course.
I had real world weather on and felt much more confident when using the CDI for verification only, keeping all heading inputs manually (with the bug) or flying the whole thing with the AP off.

As my normal enroute Nav comes from the ("sissy"  :P) Civa INS, I usually don't run into trouble with this issue. The Civa turns are smart and right on time, corrections are done fast and with close to no overshooting.
If I would go VOR to VOR only, I'd tend to use the manual heading bug and get the wind readings from the Civa, to set up the wind correction course.
As said, approaches aren't a problem since the plane is slower and turns better then, so the AP can throw her around way better.  :D
I've tried it around 210 knots, some flaps out and 3000ft when being within 15-8nm from the station. Worked fine. Even landed later, a bit hard though, but the crew remained silent until arriving at the gate where they ran away, screaming for help.
http://img850.imageshack.us/img850/9162/parkingatbrisbane.th.jpg

I remember the 707 to be way better on the VOR to VOR thing, only getting distracted by the cone of silence above the stations, but coming on the right Course pretty fast in between.


Good post, thanks.  I a will take a look at the 707 autopilot section in the aircraft.cfg and compare it to the 727.  Perhaps the autopilot was improved in the 707.  I don't think I have gyro drift enabled, but I will check it out.

Title: Re: AUTOPILOT-the only thread please
Post by audiohavoc on Apr 21st, 2011 at 4:38pm

CoolP wrote on Apr 21st, 2011 at 2:14pm:
Are you running gyro drift enabled in the FSX realism settings?
Maybe there's an offset between the indicated course and the real one and the AP then goes for the real one (internal FSX value) while you see the deviation on the CDI, because it shows you the offset value. This is just guesswork of mine though.
Would be a typical sim problem of course as real planes would always see the offset only on both systems.

I didn't have the 727 much on VOR to VOR enroute nav, only in the approach or departure phase where I was trying to follow some STAR and SID (which sometimes are described for the "old nav" too). I usually went for manual headings there though because she struggled with the short distances to the VORs when trying to catch the radials. Together with the slow AP turn rate, this really was some "chasing the needle" thing and isn't recommended.
So I just took the CDI to confirm my manual headings, not as primary source of driving the AP.
But your mentioned 30nm to 60nm sound very reasonable of course, she should work fine there.

Have to try this in some later flight I think.


When flying SID/STAR procedures, I don't track radials unless they are specifically requested by the procedure; instead I fly using headings and I use DME to determine where I am on the chart.

Title: Re: AUTOPILOT-the only thread please
Post by audiohavoc on Apr 21st, 2011 at 5:44pm
Thanks CoolP! I did have gyro drift enabled, and with it disabled the 727 autopilot is tracking VOR radials much more precisely now.  

Title: Re: AUTOPILOT-the only thread please
Post by CoolP on Apr 21st, 2011 at 8:46pm
Ah, I can tell you about some trouble with that odd sim gyro drift feature here, not on the 727 though.
This, for me, is one of the FSX items to remain off forever since it doesn't get the thing to be more realistic, but to be more buggy.  ;D

Title: Re: AUTOPILOT-the only thread please
Post by wigerup on Jun 17th, 2011 at 8:17am
On some pages it talks about a Block 5 autopilot, what is that???
Regards
Bjorn :)

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