scottb613

Falcon 50 - AP Unstable Intercept of GS.

Recommended Posts

Hi Folks,

P3Dv4.3

Actually had time to fly an approach last night - my first with this aircraft - actually... Sunday morning's update on the Falcon - the RNAV LPV for 24 into KACK with the RXP GTN 750... Wow - it was a completely unstable roller coaster ride once I intercepted the GS... About 160 KIAS before the GS - 2nd notch of flaps - gear down - when GS became active dropped flaps 3 - 140 KIAS - lol - forget about it - the oscillations seemed self perpetuating and became massive in magnitude - to the point of being fatal... I didn't have more time for testing...

Oh - the taxi light bloom can be left on with the gear up  - looks silly... Yeah - I know - turn the light off first - kinda affects the immersion though when you forget... I know we spoke of the light bloom before being visible even in bright clear daylight... Is there anyway we could make the light bloom an option - I really don't care for it (is it always visible in FSX ?) - the bloom is main reasons I bought the "Immersion" package for the Lear... Any shot we could try the dynamic lighting features in P3D ?

Also noticed in the fog - the landing lights are casting a perfect well defined rectangle of light on the ground poly - not the normal lighting like we see...

The confused GTN (double GPS) problem is back - first load - then normal on subsequent load - without changing anything... RXP GTN 750 single install is what I use...

Does entering the weight on the panel gauge actually do anything - or it just a reminder ? It's not the fastest thing in the world to set - could we get a click spot to cheat and just populate the weight ?

Regards,
Scott

Edited by scottb613

Share this post


Link to post
Help AVSIM continue to serve you!
Please donate today!

2 hours ago, scottb613 said:

Hi Folks,

P3Dv4.3

...

Also noticed in the fog - the landing lights are casting a perfect well defined rectangle of light on the ground poly - not the normal lighting like we see...

...

Regards,
Scott

I have also this rectangle with P3Dv3

  • Like 1

Share this post


Link to post
4 hours ago, scottb613 said:

Hi Folks,

P3Dv4.3

Actually had time to fly an approach last night - my first with this aircraft - actually... Sunday morning's update on the Falcon - the RNAV LPV for 24 into KACK with the RXP GTN 750... Wow - it was a completely unstable roller coaster ride once I intercepted the GS... About 160 KIAS before the GS - 2nd notch of flaps - gear down - when GS became active dropped flaps 3 - 140 KIAS - lol - forget about it - the oscillations seemed self perpetuating and became massive in magnitude - to the point of being fatal... I didn't have more time for testing...

Oh - the taxi light bloom can be left on with the gear up  - looks silly... Yeah - I know - turn the light off first - kinda affects the immersion though when you forget... I know we spoke of the light bloom before being visible even in bright clear daylight... Is there anyway we could make the light bloom an option - I really don't care for it (is it always visible in FSX ?) - the bloom is main reasons I bought the "Immersion" package for the Lear... Any shot we could try the dynamic lighting features in P3D ?

Also noticed in the fog - the landing lights are casting a perfect well defined rectangle of light on the ground poly - not the normal lighting like we see...

The confused GTN (double GPS) problem is back - first load - then normal on subsequent load - without changing anything... RXP GTN 750 single install is what I use...

Does entering the weight on the panel gauge actually do anything - or it just a reminder ? It's not the fastest thing in the world to set - could we get a click spot to cheat and just populate the weight ?

Regards,
Scott

Good Morning Scott,

I think you have a bad install. I have found it is important to uninstall a previous install (via Control Panel Program and Features) and ALSO to manually clean out any remaining folders/files in the Falcon50 install location.

I just installed Beta 4.4 and did not see the issues you have listed above:

ILS approach was reasonable.

Installed a single RXP GTN 750 -- looked fine.

At night did not see any taxi light with the gear up and the taxi light switch still on. And although I'm not as discerning as you, the landing lights seemed ok, certainly did not cast a sharp rectangle of light like I've seen before in FSX.

The Gross Wt counter counts down as fuel is burned. As I understand it, it is your pretty co-pilot's job to set the counter before engine start. Therefore you should sit in the co-pilot's seat to set the counter. Then to active the counter, use the mouse wheel to click on the counter knob. 

Al

Share this post


Link to post
26 minutes ago, ark said:

Good Morning Scott,

I think you have a bad install. I have found it is important to uninstall a previous install (via Control Panel Program and Features) and ALSO to manually clean out any remaining folders/files in the Falcon50 install location.

I just installed Beta 4.4 and did not see the issues you have listed above:

ILS approach was reasonable.

Installed a single RXP GTN 750 -- looked fine.

At night did not see any taxi light with the gear up and the taxi light switch still on. And although I'm not as discerning as you, the landing lights seemed ok, certainly did not cast a sharp rectangle of light like I've seen before in FSX.

The Gross Wt counter counts down as fuel is burned. As I understand it, it is your pretty co-pilot's job to set the counter before engine start. Therefore you should sit in the co-pilot's seat to set the counter. Then to active the counter, use the mouse wheel to click on the counter knob. 

Al

Hi Al,

I only flew one approach - so not a comprehensive test by any means...

Had a side bar with Jean-Luc - I had just updated my RXP GTN software earlier that day as well - maybe something related to his new release - or a combination thereof ?  As always - I won't be home until the weekend to test - I'll try a fresh load when I get in... One test Jean-Luc wanted to see - is there any difference between the GTN GPS GS capture - and a true ILS GS - AP capture...

Pictures are worth a thousand words - for the other issues - I'll take some screenshots - then - as well...

Thanks Pascal - at least I know I'm not seeing things...

:tongue:

Regards,
Scott

Share this post


Link to post
28 minutes ago, scottb613 said:

Hi Al,

I only flew one approach - so not a comprehensive test by any means...

Had a side bar with Jean-Luc - I had just updated my RXP GTN software earlier that day as well - maybe something related to his new release - or a combination thereof ?  As always - I won't be home until the weekend to test - I'll try a fresh load when I get in... One test Jean-Luc wanted to see - is there any difference between the GTN GPS GS capture - and a true ILS GS - AP capture...

Pictures are worth a thousand words - for the other issues - I'll take some screenshots - then - as well...

Thanks Pascal - at least I know I'm not seeing things...

:tongue:

Regards,
Scott

Here is what I see with the landing and taxi lights on. The light seems to gradually fade at the 'edges', at least to me.

e9d96c65e0.JPG

And here is what I see in the air with the taxi light switch still on and the gear up.

4b56362435.JPG

Al

 

Edited by ark

Share this post


Link to post

Hi Al,

Thanks as always...

Taxi Light - I'm using the default taxi light mapped to my keyboard - I have the big bulbous light bloom even during the brightest day and gear retracted...

When I noticed the rectangle with hard edges - it was raining and foggy as well - not sure if that means anything different to lighting...

No worries and no rush - I'll test more next weekend...

Regards,
Scott

Share this post


Link to post
4 hours ago, scottb613 said:

I'll test more next weekend...

Post an image with the exact sim and weather settings.

  • Like 1

Share this post


Link to post

I’ve been flying a lot of ILS approaches in the past couple of days since there was a recent fix to the glideslope needle which had become inop around the time of Beta 4.2. I’ve been using both the default clear skies theme (no wind), and Active Sky weather injection, and have had no issues with instability at all on any approach. The aircraft always tracks the glideslope well.

Now that RXP has released their GTN update for P3D 4.4, I’m going to go ahead and bite the bullet and install the 4.4 client and content updates on my sim computer - so my Falcon 50 testing going forward will be in P3D 4.4 as of tomorrow, and with the new version of the RXP GTN750

Jim Barrett

  • Like 2

Share this post


Link to post
1 hour ago, JRBarrett said:

I’ve been flying a lot of ILS approaches in the past couple of days since there was a recent fix to the glideslope needle which had become inop around the time of Beta 4.2. I’ve been using both the default clear skies theme (no wind), and Active Sky weather injection, and have had no issues with instability at all on any approach. The aircraft always tracks the glideslope well.

Now that RXP has released their GTN update for P3D 4.4, I’m going to go ahead and bite the bullet and install the 4.4 client and content updates on my sim computer - so my Falcon 50 testing going forward will be in P3D 4.4 as of tomorrow, and with the new version of the RXP GTN750

Jim Barrett

Jim, if you are using the REX WX Radar, be aware the REX team is still working on an update for P3DV4.4. Apparently the current version causes CTD in P3D v4.4.

Al

Share this post


Link to post

Thanks for the heads up. I do use the Rex radar. I’ll wait in that case. No big rush for me to install 4.4

Share this post


Link to post

I also experienced the same symptoms also during an LPV approach with the RXP GTN750. Huge oscillation in the glideslope and it will surely crash if i let the AP continue.

The aircraft is very stable though in ILS approaches.. I think the issue is just with RNAV LPV approaches.. Will test more later. 

Share this post


Link to post
54 minutes ago, snapshot21 said:

I also experienced the same symptoms also during an LPV approach with the RXP GTN750. Huge oscillation in the glideslope and it will surely crash if i let the AP continue.

The aircraft is very stable though in ILS approaches.. I think the issue is just with RNAV LPV approaches.. Will test more later. 

The runway where I have been testing the ILS performance also has an LPV approach. (Same IAF, descent angle and minimums as the ILS). I’ll try that in the morning and see how it goes...

Share this post


Link to post
13 hours ago, scottb613 said:

When I noticed the rectangle with hard edges - it was raining and foggy as well - not sure if that means anything different to lighting...

I also have this rectangle but only on foggy weather. I use REX 4 Texture Direct - HD with Soft Clouds. I do not have it with a rainy or cloudy or clear sky. 

Share this post


Link to post

Fixing the issue now as i agree the RNAV is nothing like the ILS and is oscillating. But only for P3D V4. RNAV works fine in FSX.

Edited by Flysimware

Share this post


Link to post
2 hours ago, Flysimware said:

Fixing the issue now as i agree the RNAV is nothing like the ILS and is oscillating. But only for P3D V4. RNAV works fine in FSX.

Hi Mark,

Thanks so much for going the extra mile - I only get a limited amount of time in front of my PC on the weekends - so it's hard for me to test thoroughly or in a timely manner...

Regards,
Scott

Share this post


Link to post
4 hours ago, Cool said:

I also have this rectangle but only on foggy weather. I use REX 4 Texture Direct - HD with Soft Clouds. I do not have it with a rainy or cloudy or clear sky. 

Hi Pascal,

So it seems to be fog then as the common denominator...

Regards,
Scott

Share this post


Link to post

Hi Folks,

One other thought came to mind that I haven't had an opportunity to check myself...

Has anyone done any "non precision" RNAV approaches (LP/LNAV) in this bird - these are the ones with a "(MDA) minimum descent altitude" vs "(DA) decision height" and these do not provide vertical guidance - it's up to the pilot to step down to the various altitudes... Does that work correctly with the model - meaning no vertical guidance is supplied to the AP ?

Thanks...

Regards,
Scott

Edited by scottb613

Share this post


Link to post

I just shot the RNAV/LPV approach to runway 24 at KELM, and confirm that the autopilot is unstable in pitch in descent. The LPV glideslope needle itself is correct, and if track it manually in v/s mode, it all works out fine. I know that FSW has identified the cause, and no doubt a fix will be forthcoming shortly.

I am now using the updated P3D 4.4-compatible version of the RXP GTN750, but I am holding off on updating the sim to 4.4 until the Milviz weather radar is updated.

I have not done a non-precision RNAV approach yet, but will try that later today

  • Like 1

Share this post


Link to post

Hi Jim,

Thanks for the confirmation as well...

Regards,
Scott

Share this post


Link to post

The GPS RNAV approach issues with the glideslope do not show up with the Flight 1 as we tested tonight. I have reported to RXP that it only happens with their GTN 750. But we have not tested other RXP units.

Share this post


Link to post

Hi,

A more recent post seems to indicate Beta 4.5 runs fine now?

 

Share this post


Link to post

I have tried one LPV approach with the RXP GTN750 since updating to Falcon version 4.5 this morning, and there was no pitch instability as before. The beta release notes mentioned improvements in the LPV vertical tracking without specifying RXP or F1, so perhaps Mark found something “fixable” since his last post above.

  • Like 1

Share this post


Link to post
1 hour ago, JRBarrett said:

I have tried one LPV approach with the RXP GTN750 since updating to Falcon version 4.5 this morning, and there was no pitch instability as before. The beta release notes mentioned improvements in the LPV vertical tracking without specifying RXP or F1, so perhaps Mark found something “fixable” since his last post above.

Jim,

One thing we noticed with the RXP 750 was the yellow GS indicator 'started' about a 1/4 dot low on the GS scale compared to other GSP units when clearly approaching the GS from well below.   Would appreciate if you could check this. 

Al

Share this post


Link to post
6 minutes ago, ark said:

GS indicator 'started' about a 1/4 dot low

This could either be a problem of calibration from the GTN (where is the 0 value), or a problem of scaling on the instrument (when reading FltSim Var GS deviation value in percent, is 100% 2.5 dots, or is 100% 2 dots? - believe me, most gauges agree on a certain value and the SDK explicitly says otherwise...)

The former must be addressed in the GTN. For the later though, there are both CDI and GSI scaling factors available in the GTN Settings Panel | Gauge Settings | Advanced Settings.

To cross-check if this is a calibration issue: during POST when on the TEST page, make sure to validate 1/2 deflection up and 1/2 deflection right are indicated! This is what it is meant for!

Edited by RXP

Share this post


Link to post


deleted

 

Edited by ark

Share this post


Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now