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Aircraft throttles malfunctioning?


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I downloaded a few 747-8's from the library and fixed the issue with the flight controls.

But when on approach, when the pink diamond of the glideslope reached level flight, the plane starts descending but then within seconds the throttles are increasing and decreasing on their own every time, regardless the speed I've set and the aircraft isn't overweight.

 

Am I doing wrong approach landing or is it something making it in the cfg file?

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Sounds like your making a bad approach to me.

 

Before capture of the GS, you should be at approach speed, flaps set for landing, and gear down. If you have none of this set, you AT will go nutty trying to play catch up as the flaps / gear extend during final decent.

 

And what exactly do you mean by "fixed the issue with the flight controls"? What did you change and why?

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When I flew with one of the plane, the trim pitch was offset in the cfg file. The fix was found here https://www.flightsim.com/vbfs/showthread.php?228555-Skyspirit-747-8I klarkcent's post #13

 

For the landing, all of them are already set before pink diamond reaches level flight. After capturing the glideslope and descending, I only reduce speed (if necessary) to keep the nose about 5 degrees above level flight because usually the plane pitches down a bit after capturing the glideslope. Other than that I don't do anything else.

I've also noticed when low on fuel this happens but with full fuel it doesn't happen, only might slightly happen when I get closer to final. But it's completely ridiculous to land with full fuel + the payload and at around 175+ kias.

 

[WEIGHT_AND_BALANCE]

empty_weight= 421200.000

max_gross_weight= 975000.000

 

If the gross weight is around 650000 and less, it happens.

If the gross weight is high amount close to the max gross, it rarely happens, sometimes just slightly upon final.

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You shouldnt be changing speeds at all during final approach. You should already have your V-speeds calculated and set. If your fiddling with it after GS capture, that makes the autopilot increase and decrease speed to keep itself on the GS track. The reason it happens with different weights more than others is because your not using the correct approach speed for your current gross weight.

 

Your autopilot is supposed to pitch nose down on GS capture, leave it alone. I strongly suggest watching a video on youtube of a ILS & Visual landing tutorial.

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I saw many of them but none show it in complete details. I've been using this video for ILS approach for a very long time. Sometimes everything is fine, sometimes the throttles go nuts and I'm wondering if it's because of certain aircrafts designed to fly with. Like the model, the cfg file, etc etc

 

I will make a video using a 747-8 and show you my complete approach.

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Here this is an approach I made with this one

https://www.flightsim.com/vbfs/fsview.php?do=list&fid=154790

 

https://www.youtube.com/watch?v=KQnJm7TT5xs&feature=youtu.be

 

I didn't change the payload, everything is still default, just fuel low.

If I set speed slower than 160 the plane will be too pitched up and if I set speed more than 160 the nose will pitch too down. I also didn't change speed after capturing the glideslope.

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Here this is an approach I made with this one

https://www.flightsim.com/vbfs/fsview.php?do=list&fid=154790

 

https://www.youtube.com/watch?v=KQnJm7TT5xs&feature=youtu.be

 

I didn't change the payload, everything is still default, just fuel low.

If I set speed slower than 160 the plane will be too pitched up and if I set speed more than 160 the nose will pitch too down. I also didn't change speed after capturing the glideslope.

 

One thing I will certainly recommend you do to eliminate the throttle hunting, (constant going up and down) is to change the max_throttle_rate In the autopilot section of the aircraft cfg. It looks like right now it is at .03000. Try going to 0.1000.

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That didn't work. I tried multiple approaches. I have the same problem in other planes too not just these 747-8's. I have a MelJet 777-300ER United Airlines also with that problem and that plane has already that throttle rate at .1000 or .10. The only way so far that is stopping throttles from doing that is to set fuel at 0 and fill in the payload. This is very weird. Doing that will also require the approach speed to be higher at around 175+ KIAS and then on final it becomes too fast

Have you tried a landing with the plane?

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Possibly similar plane.

I have a plane that approaches fine, level at 3000, app engaged. Then, at 10nm it just dives below the glideslope, and never levels off or climbs back to it but crashes before the runway is reached.

I suspect it has a wrong centre of gravity, weight, and or too little elev-trim control. (elev trim is what the autopilot uses to control altitude).

 

It is a L1011 (will add .zip filename to the post if I find it. Actually, I wrote about it before, so if you search il88pp + l1011 + pan am, you will probably find it.).

I haven't done many flights with it yet, the vc looks great but many buttons don't work, but I will try squeeze in a few to test further.

I think the engines 'surge' while it dives below the glideslope, but I would need to fly it again to be sure.

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To put it in a simple way, we all fly the right way. We fill in the aircraft with some payload so as fuel then when arriving at destination the fuel is probably low so we land and the aircraft is "unlandable". I'm going to keep on testing stuffs and I'm also going to use the default 747 cfg file data and air file for the 747-8. There are several youtube videos of 747-8 but I don't know if all of them are from skyspirit.
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Well this is weird then. Plus I just saw the cfg file, same empty weight, max gross weight, fuel and payload.

 

I tried with 0 fuel and full weight (975000) and the engines are not auto increasing/decreasing constantly. Just like I did with the MelJet 777-300ER United Airlines.

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