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hifly

DC-8 FSX issues

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   I uninstalled and then reinstalled v2.0 then upgraded to v2.1.  No vibrating scenery at the gate this time. But several serious issues during the takeoff and climb.

 

1.   Handflew the aircraft to 8000 agl and then activated AutoPilot maintaining correct climb EPR (per charts based on altitude/RAT) and pitched using VS to maintain 250KIAS.  Shaking (or vibrating) panel began immediately.  But outside view showed stable climb.  Then the aircraft began pitching down and I tried to raise the VSI using the AP but it had no effect.  Finally was able to regain stable flight by aggressively applying UP-Trim using the NUM 1 key.  It gradually responded and I had to  immediately use DOWN-Trim to stabilize it and readjust the AP VSI to maintain 1000 fpm climb.  Shaking continued and then suddenly the aircraft began again pitching down rapidly.  This struggle continued until I was almost at my cruising altitude and then it settled down and I was able to smoothly level off with VS=0.  Everything has been stable for the rest of the cruise.

 

2.  I had engaged the AUX HYD during start and since I needed engine icing during taxi and takeoff, I left them on during the takeoff.  At 2000 ft my outside view showed the gear still down even though the gear handle was up.  By trial and error, I finally shut down the AUX HYD and the gear immediately went up.  Why should having the AUX HYD prevent the gear from actuating? 

 

3.  As the temperature decreased in the climb, I kept adjusting the EPR to match the performance values for my weight (210,000 lbs).  When my RAT dipped below 45C, the charts recommended raising EPR to 2.02 but the dials would not show anything above 1.99.  The pointer stayed at 2.00 and would not respond to further rotation of the  setting knob.

 

4.  Since I use FSX,  the scenery is out of sync with current charts so I have to adjust the position of some waypoints in takeoff procedures and landing procedures.  Even though I capture and track published airways once on course, my flight plan shows up in FSX as "GPS or Direct" and the automatic INS input gadget therefore won't accept it.  I can't use PFPX for routing because I am unable to enter DC-8 as an aircraft selection.

 

5.  The 2-D autopilot is a great and necessary improvement but the left hand dial is non functional in the 2-D but works correctly on the pedestal. 

 

  I use ASN as I do with all my study aircraft and have never had issues.  I am currently completing the cruise portion and will shortly begin the descent phase where I expect the shaking and the oscillations to again be an issue.  I watched several YouTube videos and the aircraft smoothly climbs and descends without issue.  Of course these were using the PD3.4 versions, not the FSX  I am following the expanded checklists so I don't think it is a user issue.  I have not tried version v2.0 to rule out the new version as being the cause of the instability issues.  Any suggestions?

 

Craig.

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I'm going to reinstall my FSX version using the Aerosoft installers to make sure that there isn't a disconnect between the installer version and my development version as happened with P3D, after which I'll reply again here.

You are correct -- the EPR bug won't go past 2.0.  But this is only a bug to make it easier to quickly set the actual EPR with the throttle or as a reminder of the desired power setting.  It has no effect on what the engines do.  

There have been problems with hydraulics in the past and it seemed they had been fixed.  The hydraulics coding is complicated because of the mix of hydraulic and electric pumps and the inability to turn off the engine driven ones using the default system.  I will look at this but in the meantime I would suggest only turning on the electric AUX  briefly to test it as per the checklist.  There is no reason to have it on otherwise, unless you are simulating some kind of failure. 

Could you please try a climb or descent using autopilot without ASN running?  I don't use ASN and thus having you trying without it running is the only way I can rule it out as a possible cause.

The pitch dial on the autopilot works the same in 2D as in 3D on my install, but I will try again after using the Aerosoft installers.  The pitch dial can only be used in v/s or PITCH DAMP modes.  IAS HOLD and MACH HOLD were not implemented on 50 series DC8s and the dial won't stick in those positions. Pitch damp mode is for when excessive turbulence causes the autopilot to start oscillating in pitch.  PITCH DAMP will turn of the autopilot vertical mode which you can then control manually using stabilizer trim. 

For PFPX see the following post:

For the flightplan problem, just post it here and I will see if I can sort it out. 

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I just did the tutorial flight takeoff and climb out on both 2.0 and 2.1 in FSX.  I had no problems with the AP on during the climb at all.  So I think it must be your weather program, some other addon that tries to fly the plane, or a controller issue that is messing with the flight controls, trim or AP.  Again, the weather program I can't rule out until you test aircraft without it running. 

 

I do now recall shaking during development (well before beta testing) at one time when the aircraft was in the AUX/INS lateral mode and I was using some version or other of the OPUS weather program. The INS uses custom AP coding and I remember it didn't work well with the weather program for a couple of flights and then it seemed the problem just went away.  What lateral mode is selected when you turn on the AP?  However, I recall it didn't affect pitch.  It just caused the ailerons to flutter and when it got bad the aircraft was more or less shaking. 

 

Maybe you could make a brief video?  If you have windows 10 you can do this with the Windows key + G. 

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I also have the same issue as hifly.........Shaking,vibrating unable to control climb with the vs..........I also run ASN.

Had no issues until the latest version was installed................. FSX SP2

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I never tried v2.0.  I immediately upgraded to v2.1.  Just so I was on the same page as Michael, I loaded the tutorial with ASN off and did it step by step to make sure I wasn't missing something.  The shaking started on the takeoff roll, but I thought maybe that was purposely programmed to add realism.  It handflew easily on takeoff but after I intercepted the radial to MKK and activated the autopilot, the problems began.  Occasional shaking but the big issue was that it would not hold the climb.  I had to manually keep trimming up and down to keep from alternately overspeeding or stalling.  Once above 30,000 ft everything calmed down and pitch/vertical speed seemed to "almost" hold my settings without trimming.  Once at 33000 ft with VS=0 it totally behaved itself with one exception.  The cabin altitude continued to climb way above my setting.  I terminated the flight at waypoint 2 and the cabin altitude was over 5500 and still climbing at 300 ft/min,  not responding to the vertical speed knob.  The dial settin for 33000 ft showed it corresponding to a cabin altitude of  4500 ft.  I hadn't noticed that issue on any of my previous flights.  Based on Dcon's post, I think I will reinstall v2.0 to see if it will fly without these issues.  I do like the ability to access the AP on the 2D, but I think I can copy the gauge settup from v2.1 and install it in the panel for v2.0.  If that is the case and v2.0 has no issues then I will avoid the upgrade.   Any further comments or suggestions will definitely be appreciated!

 

Craig

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Testing routine (FSX SP2):

 

1.  First test was reverting to V2.0 and adding in the 2D panel fix.  With ASN active, parking brakes were unable to hold aircraft long enough to initialize INS.  Thinking the new 2D panel might have some bearing, I removed it from the panel config, and then reloaded aircraft.  It still failed to hold position.  Turned off ASN, set winds to 0.  Still plane kept creeping forward at the gate.

 

2.  Next (still using v2.0 and without the 2D autopilot)  I loaded the tutorial flight and after configuring correctly according to the expanded checklist and setting in performa as recommended, I commenced the flight from PHNL 8R.  Takeoff was uneventful, all seemed to be realistic.  After flap retraction, I accelerated to 250K and then the vibrating began and lasted on and off throughout the climb.  After activating the autopilot the plane seemed to continue to stabiley climb at 250K and then suddenly it began to climb at greater rate and lose speed.  I checked the VSI on the AP and it was reading 3200 fpm!  I immediately lowered it to VS=0 to regain airspeed.  The plane was unresponsive, so I applied manual trim using NUM 7 key and it began to respond.  After recovering airspeed and resetting VSI to 1000 fpm the aircraft seemed to stabilize at 250K then suddenly lost pitch and began to descend increasing the airspeed.  My VSI was still set at 1000 fpm climb and increasing it further did not stop the accelerating descent.  I again had to use trim (NUM 1) to finally begin to reverse the trend and eventually got it to stabilize in climb at 300K above 10,000 ft.  It was  Impossible to attain the promised results given in the tutorial, however.  I had to leave the EPR at takeoff setting just to maintain 500 ft climb at 300K..  Everything then seemed to be stabilized until I began the turn at MKK.  I tried to coax it gradually but still the aircraft would not hold altitude let alone continue to climb.  It began to rapidly descend as soon as the turn began and again required aggressive manual trimming just to stop the descent.  It was impossible to begin to regain altitude while the aircraft was still banking.  After the turn I regained altitude, stabilized airspeed and again established my 500 fpm climb.  Eventually I leveled at 33000 and the aircraft behaved as it should.  It held the altitude perfectly.  During the mach climb the aircraft would not climb at 500 fpm above M.72 even at full takeoff EPR.  Leaving it at this high setting, the aircraft would not accelerate above M.81 in level flight.  Reducing to the recommended (by the tutorial and the performance charts) EPR resulted in the aircraft only able to sustain M.74.  Did anybody actually try this tutorial with the boxed  FSX version during testing?

 

Conclusions:  Not to intentionally offend anyone, but the FSX (boxed) version does not seem to be tweaked to the same extent that the PD3.4 versions I observed on Youtube.  In those videos the plane held the autopilot climb settings and did not lose altitude during turns and definitely did not appear to exhibit any vibration or shaking.  I observed no one having to use manual trimming once under AP control.  And all of the videos had WX engines active (one had REX the others had Active Sky).  One flight started cold and dark and had no problem aligning the INS (apparently brakes correctly held the aircraft in position).  I know that the majority of respondents on this forum are PD3 version 4 users and apparently that version had undergone much greater refining.  Perhaps the same for the FSX steam version, but I have the original boxed version of FSX upgraded to SP2 and my experience with the DC-8 simulation has not been positive.  Both version 2.0 and version 2.1 exhibit unstable flight dynamics in climbs and descents and do not perform according to the real world charts..

 

And BTW, I don't have an external controller.  I use the mouse for pitch/roll and the keyboard for rudders.  

 

Craig  

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The P3D and FSX versions have exactly the same systems coding and flight model data.  There is no difference as to how they perform in the sim.  The P3D version has some different lights and the VC textures were darkened a little as they get rendered differently in P3D.  Also, the FSX logic coding is broken into 3 files whereas in P3D it's in two files as the two sims have different maximum gauge file sizes.  FSX Acceleration introduced a better drag rise due to mach table, so if you don't have Acceleration, you may find the EPR cruise setting don't give you exactly the correct mach speed, although it should still be close - - not way off as you are describing. By the way, you should know that the aircraft has realistic icing simulated.  If you fly in icing conditions ice buildup will progressively cause increased drag and a loss of lift unless you use the deicing system on the FE panel.  When it's on, the effect of icing will gradually dissipate. 

 

In terms of cabin altitude, are you sure that the low pressure manifold switches and cabin compressors were turned on?

 

The product has been out for some time and there are many people using the FSX version and no one else has reported these issues.  So it must be something unique to your install and setup.  The fact that you a using the mouse as a controller is interesting -- I have never done that so I will give it a try to see what happens. 

 

 

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We should make sure XML Tools is properly installed.  Can you check the dll.xml file and see if there is an XMLTools entry?  Without XMLTools installed, many aircraft systems won't function correctly.  On my system  it's located as follows: C:\Users\Michael\AppData\Roaming\Microsoft\FSX\dll.xml .  You can open the file with notepad.

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Hi Michael!

    Thanks for your diligence in responding.  I am sure FSX SP2 and FSX acceleration operate the same way.  It is just two different paths to the same outcome.  My use of the mouse as my controller should also not be an issue because the problem I am having with both versions of DC8 (other than the inexplicable occasional shaking/vibrating) is solely with the VS function on the AutoPilot.  The rest works OK.  I have an early version of B727 and it has very similar autopilot.  When active the autopilot should auto-trim and it must be doing so in level flight (VS=0) since it adjusts altitude for varying pressure without difficulty.  It seems at times to respond to VS commands (as long as I change them very slowly) but then out of the  blue it suddenly goes haywire with no observable cause.  This happened even on the tutorial flight with no ASN involved.  As for  the observed inaccuracies in performance vs EPR settings, again no ASN involved and no icing conditions present during the entire flight.  The only add-on I have loaded with FSX is GSX v1.0 but I did not call on it since I started at rwy 8R with engines running.  I also have FSUIPC registered version installed but not active.  The only time I use it is to monitor VAS when using ORBTZ scenery in combination with a PMDG model.  Not the case here, so it shouldn't have been a factor.   I have XMLtools installed.  And I have no other addons.  All my other complex aircraft have no instabilities.  I regularly use PMDG 737NG, PMDG 744v3,  FSL ConcordeX,  Majestic Q400, Maddog MD80,  CapSim B727,  and a few GA aircraft.  All fly according to the performance specs without control issues.  Other than that, I don't know what to tell you, but the problems I am having with DC8 are consistent flight after flight, with or without ASN..  My computer specs: I7 7700K Quad Core OC to 5.0 GHZ, 16G fast RAM, GTX 1060 graphics.  

 

Craig

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Well Craig, I am running out of ideas.  There isn't anything for me to fix, since I can't duplicate the problem. 

 

I looked over my code for the vertical speed AP function.  It's a mix of custom code and default autopilot, mostly default.  It does use XMLTools, so it's important to check that you have the entry in your dll.xml file.  That file can be messed up by other addons.  Just because the installer ran doesn't mean it's properly installed indefinitely. Make sure you check the file and also see that the XMLTools.dll is in your root FSX folder. 

 

The SP2 vs. Acceleration issue does ring a bell with me now.  I seem to recall that the VS didn't work on the Captain Sim 727 without acceleration because it used a new variable introduced with Acceleration.  I'll try looking into that, but there surely must be other DC-8 users who don't have Acceleration, so I doubt this is the issue. 

 

Finally, I suggest going into your FSX control setting and select the autopilot event category.  Make sure there are no AP functions mapped to keys you may be using for other things. 

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I discovered the Captain Sim AP issue relates to an AP pitch hold variable that the DC-8 doesn't use, so that isn't the problem.

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One more thing -- don't use any key commands for AP controls.  Only use the 3D or 2D controls in the DC-8 product using your mouse.  Using keys for default AP commands could mess things up. 

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I know this is not a proper solution, but ...  One way to get you flying is not to use VS.  Instead, when you turn on the AP,  turn the pitch knob to PITCH DAMP and then control your VS with stabilizer trim until you get to cruise altitude.  I just tried this and it's not very different from using the VS wheel.  Also, I would be interested in knowing if it stops the shaking. 

As for shaking on the ground, try loading the aircraft before doing anything else to see if the weight stops the shaking. Also, the aircraft loads with the INS aligned -- you don't have to go through that manually.

I don't like to suggest workarounds -- I would prefer that you be able to use the product as intended, but right now I can't think of  anything else that could cause the problems you are facing .

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I really appreciate your efforts, Michael.  I do have XMLtools properly installed in my main dll.xml folder.  Also I regularly fly Capt Sim 727 and the VS command works perfectly with my FSXSP2 installation.  I have no keys mapped to autopilot functions.  I have been strictly using mouse to manipulate the VS on the autopilot panel for the DC-8 as I do for the Capt Sim.  Using pitch damp mode with manual trim would definitely be a novel approach worth trying.  Note that DCON (cf the 4th post on this issue) has the same setup as I and also reported the same issues with FSXSP2.  

 

Craig

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On 1/10/2020 at 11:14 AM, dcon said:

I also have the same issue as hifly.........Shaking,vibrating unable to control climb with the vs..........I also run ASN.

Had no issues until the latest version was installed................. FSX SP2

 

dcon:

 

Can you clarify?  It was OK on FSX SP2 until you updated the DC-8 to v. 2.1?   V2.0 was OK?

5 hours ago, hifly said:

I regularly fly Capt Sim 727 and the VS command works perfectly with my FSXSP2 installation.

 

They eventually fixed it for non Acceleration users.

 

5 hours ago, hifly said:

Note that DCON (cf the 4th post on this issue) has the same setup as I

 

Thanks for pointing that out, I had overlooked that post.  But he says he was OK until v. 2.1 if I understand him correctly. And you have the same problems with both 2.0 and 2.1, is that right?

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Michael,

 

      Yes, it worked fine until 2.1, no issues until that update.

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33 minutes ago, dcon said:

Michael,

 

      Yes, it worked fine until 2.1, no issues until that update.

 

Did you go back to 2.0 and find it works again? 

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