L35 SPD Hold

[Bjoern 1,157]

Does anyone have problems with the altitude modes?

ALT HLD is all over the place for me and I just can't get it to work with the default logic.

 

 

My only working solution/workaround after way too much time spent with this is replacing the default behavior with another custom PID controller. It seems to work much better, also when combined with ALT SEL, but one drawback is that initial capture may be a bit rough at high vertical speeds. There might also be a bit of permanent target altitude lapse of +/- 50 ft at worst due to the inherent steady-state error, but that might be more realistic than not (it's at least less than a tenth of the RVSM limit of +/- 500 ft).

[ark 1,291]

Something has clearly happened  (probably inadvertent error or unintentional consequences)  between L35 vers 2.7 and 2.8. Ver 2.7 seemed to work fairly well as far as the altitude modes are concerned, so I have gone back to ver 2.7 while adding in a few of the more minor ver.2.8 changes, like altitude alerting at 1000ft vs 300ft and the orange attitude indicator.  My guess is the ver 2.8 altitude modes problems have to do with changes in the pitch trim system area.

 

Btw, one of the listed ver 2.8 changes is:  Altitude lower deflection indicator now is for localizer only.  For some reason I don't understand what this means -- help please?

 

Thx,

Al

[Bjoern 1,157]

I have no idea what this means, but it surely isn't relevant to the autopilot issues.

 

 

VS hold mode was the next thing to fix. My first attempt using attitude hold mode and continuous target pitch adjustments didn't work too well, as did a PID controller, so now I'm using the bog standard VS hold function with unreachable target altitudes. Handoff to ALTSEL/ALTHLD modes still needs to be implemented.

[charlie130 196]

:  Altitude lower deflection indicator now is for localizer only.  For some reason I don't understand what this means -- help please?

 

Agree, this is counter intuitive. In Localiser there is no altitude guidance, except in the GTN 750 when using an RNav approach.

 

The Alt Hold only works for me when at selected altitude, or approaching selected altitude, in VS and <50 fpm?

 

Makes for a bit of swearing in the flight deck.

 

Regards

 

David.

 

I was just thinking what a well supported aircraft this is now, FSFX, REX WX Weather Radar, GTN 750 and MCE, so if we can get the AFCS right she's a little gem.

[tatfsn 2]

I've had the Lear 35 since Flysimware first released it, and have upgraded it whenever a new

version has been released.

 

I've never had any issue with the Altitude Hold; yet for the life of me I've never been able to

get the SPD mode to work reliably, regardless of which upgrade I've flown.  After much trial and

error I've worked out a set of procedures that work.    I don't know how realistic they are, but they're

the only ways I've been able to fly the airplane in a credible fashion, without causing my "passengers"

dire distress, or injury.

 

I never use the SPD mode upon initial climbout.   The result is nearly always that I lose control

of the airplane; the jet pitches up drastically to nearly vertical unless I respond quickly; easing

back on the power only causes it to drastically pitch down, and it is a handful to manage to avoid

going into a fatal dive. 

 

Upon takeoff, once airborne, I engage the autopilot, and its heading mode; ALT SELECT is also

on from the beginning.   Once the aircraft is at the attitude and rate of climb I want, with the initial

power reduction set and the flaps are retracted, I engage the VS mode.    That procedure works

flawlessly for me.

 

I've found the SPD mode to be great for adjusting pitch during climbs. but worthless for maintaining it.

I immediately engage  VS once I'm at the attitude/rate of climb I want.  That procedure also works quite

well for me.   My experience is that the SPD mode is simply too unreliable and touchy to keep engaged

through any climb phase.

 

Where the SPD mode works very well, in my experience, is during descents.   I am able to maintain negative

pitch control with it quite nicely.    That's the other mode of flight where I've found it to be of real help.

 

Just my two cents...

[ark 1,291]

tatfsn,

What sim do you use? I ask because SPD Hold works fine for me in v2.7 with the box version of FSX, and I know this is also true for a friend I fly with. So I'm wondering if the use of different sims may be a factor that helps to explain some of the differences that are being reported.

Thx,

Al

[tatfsn 2]

ark,

 

When the Lear 35 was first released I was using FSX (boxed version).    I've since switched to Prepar3d

(version 3.3) and now use that exclusively.

 

I've had the same issue with SPD hold in both versions of the sim, and in every version of the Learjet

that I've tried to use it.    Again, I've found SPD hold to be useful for the purposes that I mentioned

earlier, but those clearly seem to be not the use for which it was intended.

 

Oh, well, I still love Flysimware's latest work of art.   Their Lear and their MU-2 are just about the only planes

in P3D that I fly these days. 

[andyb_1972 5]

SPD hold in the Lear v2.8 still disastrous for me... I've abandoned SPD mode in v2.8 in favour of VS. Whenever I select SPD mode during a climb (2000ft/m @220kts), I immediately pitch up steeply, almost to a stall, before pitching down so steeply I either hit the ground or overspeed. It definitely worked fine for me in V2.7 though. I'm using P3DV3.4

[scottb613 1,188]

Hi Folks,

 

Yeah - ditto Andy - I think we're all in the same boat...

 

Best course of action is to submit tickets to Flysimware - they do respond... I've been meaning to on this issue but just haven't gotten to it yet...

 

Regards,

Scott

[chapstick 2,758]

I really want to buy this Lear since I have the GTN 750 but hearing about the autopilot issues is not encouraging... is this still worth buying? 

Alex

[ark 1,291]

12 hours ago, Chapstick said:

I really want to buy this Lear since I have the GTN 750 but hearing about the autopilot issues is not encouraging... is this still worth buying? 

Alex

Alex,

FSW has been good about addressing problems, and so I would expect the SPD Hold issue that cropped up with the latest 2.8 version will be addressed. In general I find the L35 to be a great plane and is about the only one I fly these days, although admittedly I have dropped back to ver 2.7 as far as SPD Hold is concerned. A friend I fly with uses version 2.8 and finds that if he makes sure the plane is well trimmed before engaging SPD Hold, the problem is usually manageable. Turbulent air does seem to exacerbate the problem.

Al

[Bjoern 1,157]

Despite being in contact with FSW here and there and helping with code trying to patch thing up, the aircraft is ultimately disappointing me time after time.

Next to the autopilot issues, there's the colossally dumb installer - even for the closed "work in progress" versions - that won't ever let you install the aircraft to an outside folder to check what has changed and what hasn't.

But even worse, the aircraft has a massive memory usage issue. Normally, compressing or resizing textures will shrink an add-on's memory footprint, and make it less susceptible to causing OOM errors. If I, however, cut down the shared texture folder size from 120 to 43(!) MBytes and still plunge to 1.5 GB free VAS on a bog standard airport without even having lifted off, there's something much more amiss. Not even 100 nm into a flight, I was down to 800 MB free VAS, which is just about a death sentence for the current simulator session. I'm not even running anything fancy in terms of mesh, terrain and AI addons to bog down FSX and other planes with similar complexity fare much better, regardless of larger texture folders.

The flight dynamics get a free pass, because they're hard to get right and require a separate team member to develop (which FSW doesn't have, as far as I know).

 

If I finally can get the autopilot rework up (altitude hold) and running, I'd wrap up the mod update for 2.8, but that'd be it for me for now.

[ark 1,291]

On 2/23/2017 at 11:39 AM, scottb613 said:

Hi Folks,

 

Yeah - ditto Andy - I think we're all in the same boat...

 

Best course of action is to submit tickets to Flysimware - they do respond... I've been meaning to on this issue but just haven't gotten to it yet...

 

Regards,

Scott

Hi Scott,

Did you ever submit a ticket to FSW on this issue -- any feedback?

Thx,

Al

[scottb613 1,188]

Hi Al,

Umm - err - uhh - I have been remiss in my duties - sir... Let me get it submitted as the problem with 2.8 did sap a bit of my enthusiasm as the custom autopilot was one of its best features...

Regards,
Scott

[MartinRex007 390]

Anyone having this issue should send a note to the developers, as mentioned they have be very responsive in the past. For some reason my SPD works fine up to about FL35 then goes crazy and I have to disconnect and take control while my passengers are screaming, I still use P3D 2.4 so not sure what effect the sim platform has on this glitch. Anyhow I just sent in my request asking them if they could look into this. Such a great plane so I hope they can address this annoying issue.

Cheers

Martin