Climb Performance Problems

[ual1819 1]

I've had a number of problems climbing the 737-800WL. It seems like the actual (virtual) thrust output of the engines isn't matching the indicated N1, and the autoflight system gets confused struggling to keep the plane in the air. On one flight, I was at about 12000', 98% or so N1. The FD had the plane pitched 5 degrees nose *down* and it was unable to accelerate much above 200 knots. Fuel was lightly loaded (wing tanks only) and reasonable passenger load. This flight was so out of whack I had to abort, I couldn't even maintain clean speed. My current flight started to have problems above FL200. Similar problem, trying to maintain mach .79, 98% N1 (CLB thrust), nose down and V/S of basically 0. Around 13000 lbs of fuel in the wing tanks only, and a 70% passenger load. This time, I was slowly able to resume climbing by turning off autothrottle and manually selecting 102% N1, setting the CLB speed a bit lower to mach .70. The plane struggled between 0 and +500fpm and I finally got it up to FL340. I've seen similar issues before related to OAT/TAT being out of whack, but in this case the temp appears to be reasonable. (-24c at FL340) Anyone see this and know why it might be happening? Peter Vanags

[3-2-1-Now 126]

Hi, Did you check that you didn't have the spoilers out, etc..? I climbed to FL360 last night at near MGW and there were no issues. Best regards,Robin.

[stweaver321 0]

Hi, Did you check that you didn't have the spoilers out, etc..? I climbed to FL360 last night at near MGW and there were no issues. Best regards,Robin.

Also, make sure gear is up. :) Stacey Weaver

[steve inwood 67]

Ummmm it is really interesting reading all these issues, I got to 37,000 en route to ALC no isses that i could see. It really does show that everyone's systems are all different..

[eurowing 13]

are you possibly flying online with fsinn?

[ual1819 1]

No spoilers or gear, that's a screwup I typically check for (having done it in the past....) Yes, online with FSInn, though I've had the problem offline too. I've also had a successful trip KLAX-KLAS with the same 737-800WL, climbed briskly to FL270 with no problems. Another note, when this happens, fuel burn rate is much higher than expected. FF shows 4.00 cruising at FL340. Not sure what the normal figure is, but my PROG fuel estimates are dipping into reserves now.

[eurowing 13]

thing with fsinn is that their wx engine is screwed up. make sure you use fsx weather and not fsinn weather. check the OAT when you have that problem. if it's above freezing up at altitude then you have found the reason. fsinn has the right temp number but negative temps are positive so you can find i.g. +40C at FL300. of course your engine performance will go to almost zero in that temp at that altitude.

[ual1819 1]

thing with fsinn is that their wx engine is screwed up. make sure you use fsx weather and not fsinn weather. check the OAT when you have that problem. if it's above freezing up at altitude then you have found the reason.

Right, I've seen problems like this in the past myself. I have FSInn, but REX is driving my weather from VATSIM, and the air temps look about how they should.

[audiohavoc 24]

In the FSInn UI, disable all FSInn weather and set your weather in FSX or with your external weather app if you have that.

[Mats_J 2]

Peter,This is something only a few have encountered. I did during beta but we were unable to pin it down.Can you try to replicate this without any add-ons running. Move the FSUIPC directory temporarily etc? Secondly. Please try to post a screen shot of what the panel looks like when encountering this. State FMS setup including route, SID , STAR etc. And finally would be great if you could list any and all add-ons installed. We are trying to figure out a pattern here. Thanks in advance,

[3-2-1-Now 126]

Hmm - didn't you post a screenshot? I saw +2 degrees C on *a* screenshot, about this issue. The aircraft should be able to fly at that altitude, even if it is quite warm. Best regards,Robin.

[ual1819 1]

I am also seeing thrust problems on landing (even at idle thrust and full flaps, can't slow down enough). It all seems to relate to a mismatch between indicated N1% and the actual thrust being produced. I'm going to start process of elimination with other addons (most significantly FSUIPC).

[ual1819 1]

Here's the landing thrust problem. A/T is off (was commanding around 60% N1 when on), throttles are at idle but still showing 40% N1. Full flaps on the glideslope, airspeed won't go below 165. I am beginning to suspect FSUIPC on this one. Not doing any calibration with FSUIPC, but it is assigning the axes. Managed to get the speed down to 145 for touchdown, about 10 knots hot, but at least I didn't bend the plane.

[ual1819 1]

Well, sure enough, disabling FSUIPC cleaned up all the thrust problems. A short flight KIAH-KAUS went pretty much exactly by the numbers. No problems with insufficient climb power, and no overspeed on approach either. Now I have to figure out what to do, I can't really live without FSUIPC...

[GHarrall 494]

I am always amazed at how much FSUIPC can effect addons even though theoretically it shouldn't. I hope 'simconnect' dies a quick death. Its been nothing but trouble.