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fwerff

Can not maintain cruise speed

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Yesterday, since quite some time, I took the MD-11 out of the hangar again for a nice long (loooong) flight from KLAX to SBGL.

Had a heavy load and takeoff was at MTOW. Initial flightlevel was set at FL290, with steps to FL320, FL340 and planned FL360 though I never made it to that last FL.

Already during climb, the MD was having a hard time maintaining both speed and a healthy climb rate. Now with healthy I mean a couple of 100 feet per minute, so nothing rocket-like :-)

 

During cruise, max EPR was set to 1.17 at FL290 and later on at FL340 it was 1.10. This max EPR setting was by far not enough to maintain a cruise speed of Mach .81. Mostly it stayed around at Mach .62 which was close to stall speed.

And because of some windshifts, every now and then I lost quite some height with the MD-11 not being able to recover.

 

Workaround I eventually used (because my passengers were getting nervous and anoyed :P ) was to manually set max EPR to TO/GA of 1.71 which was enough to get her high and speedy again, but at the same time caused contiuous High EGT warnings.

 

I spend considerable time during the flight to figure out what was wrong, but I could not. Weights were entered correctly, FL was at or below the optimum FL as calculated by the FMS and there were no obvious things like landing-gear out or so... :wacko:

 

Anyone have an idea what went wrong during this flight?

Later this week I will re-fly the EGLL-LSZH tutorial flight to refresh myself on the MD-11. Been flyiing to much NGX and AS A320 so maybe I overlooked an important step during preflight....


Regards,

Frank van der Werff

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Hi Frank

 

Hmm, it sounds like there is an issue with your weather engine and how it is setting your high altitude weather, particular with regards to the temperature, I would suggest you to check the options selected.

 

Best regards

Palle

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Hi Frank

 

Hmm, it sounds like there is an issue with your weather engine and how it is setting your high altitude weather, particular with regards to the temperature, I would suggest you to check the options selected.

 

Best regards

Palle

 

Hi Palle,

 

I used the latest (beta) version of OpusFSX. I will make a short flight with Opus and after that a shot flight with AS2012. Never occurred to me the weather program might influence this.

Thanks for the response!

 

 

 

Sent from my iPad using Tapatalk HD


Regards,

Frank van der Werff

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What was the T.A.T? Dont care what weather engine you use. FSX will mess this up on occasion and cause HUGE performance issues. Specially with the more complex developers aircraft.

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What was the T.A.T? Dont care what weather engine you use. FSX will mess this up on occasion and cause HUGE performance issues. Specially with the more complex developers aircraft.

Ever seen that with IF weather?

Steve Waite: Engineer at codelegend.com

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If weather is not your issue, are you using FSUIPC to calibrate/saaign the flaps ?

 

Someone else had issues I remember caused by calibrating/assigning through FSUIPC.

 

Peter


Peter Schluter

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What was the T.A.T? Dont care what weather engine you use. FSX will mess this up on occasion and cause HUGE performance issues. Specially with the more complex developers aircraft.

 

Sorry, I don't recall what the TAT was. I will keep an eye on it during my next flight.

 

 

Sent from my iPhone using Tapatalk

 

If weather is not your issue, are you using FSUIPC to calibrate/saaign the flaps ?

 

Someone else had issues I remember caused by calibrating/assigning through FSUIPC.

 

Peter

 

Nope. All assigned via standard FSX controls.

 

 

Sent from my iPhone using Tapatalk


Regards,

Frank van der Werff

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It's possible some weather engines can leave 'holes' in the weather with entirely different temperatures in the 'hole'.


Steve Waite: Engineer at codelegend.com

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Sure your flaps were fully retracted? And the gear? Seems like your MCDU was under the impression that it was supposed to keep the speeds down for some reason..


Sander Rutte

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Sure your flaps were fully retracted? And the gear? Seems like your MCDU was under the impression that it was supposed to keep the speeds down for some reason..

 

Yup. All was clean & smooth, triple checked :-)

Tonight I will have another go at it (shorter flight though :-))

 

 

 

Sent from my iPhone using Tapatalk


Regards,

Frank van der Werff

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Are you using AS2012? If so, I know that the Beta that I am using has a strange issue. Out of nowhere during cruise, the outside temp will spike from -50 to -60 up to 35. Its like hitting a brick wall. There is a new beta thats supposed to fix it, but I haven't downloaded it yet.


Branton Turner

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Are you using AS2012? If so, I know that the Beta that I am using has a strange issue. Out of nowhere during cruise, the outside temp will spike from -50 to -60 up to 35. Its like hitting a brick wall. There is a new beta thats supposed to fix it, but I haven't downloaded it yet.

 

The last few days Ive seen a bunch of temp issues with As2012. Was climbing at 300fpm at Fl250 in the BAE146. Checked OAT. +45C. Not good. I downloaded the new beta but hav't had a chance to try it.

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Guest BeaverDriver

Nuts! Which beta are you guys on? I have #5. I haven't noticed this problem, but I haven't been looking for it either. This doesn't sound real good though.

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