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DC8 vibrates when parked, climbing, descending


hifly

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I have FSX SP2 and downloaded v2.1.  Also noticed problem with v2.0.  Only happens with this product.  When I load the aircraft in cold/dark at a parking spot, the whole scenery vibrates very slightly and the aircraft very slowly creeps forward.  Parking brake is set and I even actuated Aux Hydraulics but no joy.  The movement causes my INS not to align and I get error code.  Also interferes with GSX as the plane moves away from the stairs and service trucks.  I have I7 7700 and my frame rates are usually 80-100 but I lock at 35 fps to avoid any loading stutters.  I have tried placing the aircraft at different airports and same result.  I use ASN but set the winds to zero and still I have the vibrations affecting the entire scenery when I have the plane loaded.  When I switch to another aircraft, the problem disappears.  This first occurred with v2.0 but upgrading to v2.1 still has same issue.  I have the US-tools showing active in my tool bar but when I pull up the interface to check it requests me to sign in.  Is this an additional requirement upon installation?  Do I use my aerosoft credentials or do I have to set up a new registration just for that product?  Could that be the issue that is causing the jerky vibrations?  Please advise

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I reinstalled DC8 v2.0 and noticed no shaking at the departure gate and began flight without incidence but missed the autopilot popup so upgraded to v2.1.  Vibrating scenery came back but this time the aircraft stayed in position so I was able to align INS.  After a few minutes the shaking vibrations ceased but reappeared briefly on climbout then disappeared for the duration of the flight.  I have no clue what is causing it.  I did have ASN weather active but winds were very light.

 

Off the topic:  also noticed that the automatic INS loader does not activate after I have loaded a flight plan in FSX.  The documents state that it does not work for flights that are "GPS-direct" which would include all flights over the oceans since there are no VOR stations and no high altitude airways (only variable tracks).  Therefore waypoints need to be entered manually (as they probably were back in the heyday of the DC8/B707.)   I also observed,  when using DME updating, that sometimes one of the NAV radios fails to capture the VOR signals.  Sometimes it is the right, sometimes it is the left;  inconsistent.  I also noted by trial and error that the INS selector in the overhead must not be set to the same INS that is being updated or the update will fail to activate, i.e., if inputting DME data into INS#1 then the overhead INS selector must be set to #2 and vice versa.  Keeping the remote buttons active during the DME data input allows both to benefit from the updating.  (Must switch the updating INS to PI=4).  Not covered in the documentation.

 

Craig

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On 12/12/2019 at 12:16 PM, hifly said:

I have the US-tools showing active in my tool bar but when I pull up the interface to check it requests me to sign in

 

I don't know what that is.  It doesn't sound like anything connected to the DC-8. Can you take a screenshot?

 

On 12/12/2019 at 12:16 PM, hifly said:

When I load the aircraft in cold/dark at a parking spot, the whole scenery vibrates very slightly and the aircraft very slowly creeps forward.

 

I have never seen this and no else has reported it since the product was first released.  I know it's very easy to accidentally turn off the parking brake.  But are you saying the aircraft moves even with the engines off? Is it on some kind of custom airport scenery when this happens? Was wind perhaps a factor.  I am really struggling to understand what could cause this. 

 

On 12/13/2019 at 3:53 PM, hifly said:

the automatic INS loader does not activate after I have loaded a flight plan in FSX.  The documents state that it does not work for flights that are "GPS-direct" which would include all flights over the oceans since there are no VOR stations and no high altitude airways (only variable tracks). 

 

If you create the flight plan in FSX, just tick the boxes for IFR and high altitude airways.  It doesn't matter if it's over an ocean.  I always use third party apps to create flight plans, but I just tried with the default planner from PHNL to KSFO and it loads into the INS as it should. 

 

On 12/13/2019 at 3:53 PM, hifly said:

 I also observed,  when using DME updating, that sometimes one of the NAV radios fails to capture the VOR signals.  Sometimes it is the right, sometimes it is the left;  inconsistent.

 

I'm not sure I understand this.  It's obvious if the NAV radio has the signal, no? I think you mean sometimes one INS fails to update?  It should work consistently. It's very easy to make a mistake that will cause the update to fail.  As you noted, you must switch the INS to PI4 which is easy to forget.  It shouldn't matter which position the overhead 1 or 2 switch is in -- that only determines which unit drives the autopilot.  I don't recall there ever being a problem with the overhead switch position, but I will test and see. 

 

Finally, my apologies for not replying sooner.  I've had a busy week and didn't check the forums as often as I would like to. 

Reading over your post again, I see you already mentioned wind and scenery.  Maybe try again without any addons such as Active Sky running? 

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  • 2 weeks later...

I am still not sure what was causing the shaking (yes scenery and plane with engines off!) when I first spawned the aircraft but I haven't noticed it on the last few flights.  But, it still shakes during climbout if on autopilot (OK if I hand-fly).  Once I level off with VSI=0 it holds altitude perfectly and all shakiness is gone.  But as soon as I start descent (with autopilot) not only does the shakiness present itself again but the plane will suddenly reverse and start to climb.  Any attempt to re-establish the descent even with VSI fails.  The only solution is to disconnect autopilot and bring aircraft back into descent profile.  Once stable, I can re-engage autopilot but soon the undesirable characteristics will reappear.  I do have ASN weather but the problem doesn't seem to correlate with any wind direction/speed change.  I also am descending at idle and holding airspeed.  I am correctly loading aircraft and within CG limits.  Out of ideas.  

 

The other issue concerning INS updating was due to procedural error on my part so all sorted out now.

 

Craig

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I tested the DME update last night updating INS 1 which was also driving the autopilot.  It's not really an issue now that you sorted it out, but I will post this screenshot of my track anyway as it shows the progressive correction the update brings:

 

Please login to display this image.

 

I was able to produce some (very minimal) shaking at an addon airport when the aircraft is very light, but it wouldn't do it at a default airport I also tried.  I have never seen shaking while in flight.  I would suggest trying without Active Sky even running at all just to rule it out.  Other possibilities could include some other addon that is trying to control the autopilot.  Or you might have inadvertently mapped some flight surface or autopilot controls to multiple controllers and they are essentially fighting with each other to control the aircraft.  Another possibility is using FSUIPC to control flight surfaces, particularly elevator trim.  The DC8 has a fairly elaborate custom trim system so as to achieve the correct rate of trim over time and very fine increments using default commands.  I'll try to think of other possibilities.  It must be user specific as I don't think any similar problem has ever come up in the forums or during beta testing. 

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I have uninstalled and reinstalled to see if it was some anomaly caused during my initial installation.  I have FSUIPC loaded but don't use it for anything other than VAS monitoring when using PMDG in ORBTZ scenery areas.  I will disconnect ASN during my next test flight if I still notice shaking.  Thanks for your input.  Again, for reference, I am using FSX SP2 (boxed version).

 

Craig

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  • 1 month later...

I have the shaking issue also.I am running P3D v4.5 and that is also the version that has the hydraulic problems.Maybe this is a P3D problem,after all.

I am running the dc8 on windows 10,along with  ASN and  GTX world scenery and vector.

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  • 2 weeks later...
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I believe we have three users reporting this and it now seems it cannot be linked to FSX non-acceleration as one user reports it occurring in P3D 4.5.  Apparently it only occurs with the DC8 v. 2.1 but not 2.0.  

 

Since the problem is not general to all or even many users and since I have never been able to reproduce it in FSX or any verision of P3D (I am now on 4.5), I am not optimistic that a solution will be found. 

 

A new version will be coming out soon -- we'll see if the problem is still present then. 

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  • 2 months later...

I had the shaking today - hard to see from VC looking forward, but looking out side window it was clear to see..up and down very fast. I was at a addon airport MDSD - FSX:ACC user. Purchased  last week, fully up - to - date with the updater. Aircraft was at full load.

I then proceeded with take - off and crashed due to loosing eng 2&3 from fuel starvation - but that's another topic :) 

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The only other possible cause I can think of is the custom lateral autopilot when the autopilot is set to AUX, in other words when the INS is controlling your heading.  I know that some weather settings can cause what I experienced as a minor fluttering of the ailerons on one or two occasions during development of the aircraft.  Can you check in the outside view when this happens and see if the ailerons look as if they are fluttering or vibrating?

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Just to confirm, i was sat at the gate, cold and dark.

 

I just loaded another flight and all was fine. If it happens again i try what you asked.

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