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mSparks43 / 747-400

A Boeing 747-400 aircraft for X-Plane 11 & 12
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Engines shutting down too slow #542

Open MCCVeen opened 3 years ago

MCCVeen commented 3 years ago

For some reason whenever I shut the engines down the N1 decreases way too slowly. It used to be fine but now they take forever to slow down. See this video for reference of the CF6: https://youtu.be/w2BvSnWvCA0?t=1080

MCCVeen commented 3 years ago

@mSparks43 Could you have a look at this before the 2nd release?

Another reference here of the CF6: https://youtu.be/7GZ3fSDFevE?t=337

https://user-images.githubusercontent.com/75425109/119750022-ad7eb200-be98-11eb-8e43-0ad7ce42c68b.mp4

Can't find a PW example but it's pretty much the same, I'd say revert to the old shutdown rate

mSparks43 commented 3 years ago

are you talking about n1 or when the power from the gen cuts? I'm not seeing a big difference to those videos, and afaik they havent been touched (nor can they)

MCCVeen commented 3 years ago

are you talking about n1 or when the power from the gen cuts? I'm not seeing a big difference to those videos, and afaik they havent been touched (nor can they)

it has changed, just compare it to the default 747 and you'll see that they shut down faster there which is correct

mSparks43 commented 3 years ago

the default engines have something like a 5 foot diameter, absolutely nothing is right about them.

remenkemi commented 3 years ago

Speaking of default stuff, does the Sparky use the default flight model or MGouge's mod (on the org)? We might be able to get permission to copy his mod into the Sparky if not. It'll be tricky though because so much else has changed in the acf...

@mSparks43

MCCVeen commented 3 years ago

are you talking about n1 or when the power from the gen cuts? I'm not seeing a big difference to those videos, and afaik they havent been touched (nor can they)

n1 btw

MCCVeen commented 3 years ago

the default engines have something like a 5 foot diameter, absolutely nothing is right about them.

but still the rate at which the N1 drops is way more realistic

MCCVeen commented 3 years ago

@mSparks43 Could you have a look at this before the 2nd release?

Another reference here of the CF6: https://youtu.be/7GZ3fSDFevE?t=337

2021-05-27.03-02-42.mp4 Can't find a PW example but it's pretty much the same, I'd say revert to the old shutdown rate

Can this be looked at? The evidence is here.

mSparks43 commented 3 years ago

@mSparks43 Could you have a look at this before the 2nd release? Another reference here of the CF6: https://youtu.be/7GZ3fSDFevE?t=337 2021-05-27.03-02-42.mp4 Can't find a PW example but it's pretty much the same, I'd say revert to the old shutdown rate

Can this be looked at? The evidence is here.

not really, it seems to be related to increasing the maximum cruise ceiling above fl300 so given a choice between being able to cruise above fl300 or the engines taking slightly longer to stop spinning when they don't have fuel there's not much that can be done afaict.

If you can track down the exact change that caused it, and its not the bypass fan diameter then it is possible, but otherwise your guess is as good as mine.

CalibraNR commented 1 year ago

I was looking where to post it. Both starts and shutdowns are way too slow. Booth N1 and N2 (GE) takes like ages to stop, more than 10min to drop below 5% N2. Don`t know if anything can be done about it, since a lot of time has passed. Will get some reference on start and shutdown times.

CalibraNR commented 1 year ago

@mSparks43 a nice video, show how fast EGT rises during start and the N1/N2 Spool Up time. https://www.youtube.com/watch?v=P6mvYyyMHV0 The airplane in the video is a Boeing 747-412F(SCD) - PW4056. https://www.jetphotos.com/aircraft/Boeing+747-412F%28SCD%29/serial/26561

mSparks43 commented 1 year ago

pretty much agree, the main source now is the engines themselves are "too efficient", XP12 has some nice new settings for losses due to friction etc (currently 0& default just opening it in planemaker - standard, engine specs-start/spool Friction), but not had an opportunity to test them out. from the GE video I have, it takes more or less exactly 30 seconds after fuel shut off from 26.6% N1 to 4% N1, with the last bit being quicker, drop off into single digits seems about right, its the last few % taking to long afaict.