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ArjenVdv

User doesn't like engines- but has no data or experience to back it up... (not a bug... just a wasted gripe)

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Hello, This is what I don't like about the engines. They just don't behave realisticly. I know that because I've been on the 737 many times, in the front, so I could hear it. I've flown in the cockpit of a Transavia 737-800, I've seen on the EICAS how differently they behave, you can even see it in the video right under this post.The Tutorial 1 says, that after 40% N1, the engines accelerate really quickly. This is not the case because it's actually after 50% N1 on the NGX. But in the real NG, the engines accerelate really fast already after 30% N1! And also, they are much more stable. They accelerate, and immediately establish at the N1 input of the pilot. If you put in 40% N1 on this NGX, you'll have to wait ages compared to the real NG for the engines to reach 40% N1, in the NGX the engines don't establish as fast as on the real NG. If you don't believe me, watch this video, and take a good look at the EICAS at takeoff. Now compare this to the NGX. Maybe you guys are thinking: "What is this guy complaining about?". Maybe you think that, and it's a small detail indeed, but in such simulations like these, small details are really important! If you can simulate that something is 7.5343227743356235 Amps, then you can also simulate the engine dynamics. In my opinion, this has never been done right by any producer. In the 747 and MD-11 from PMDG it was even worse. When you put in 70 N1, you can wait at least ten seconds to reach 70.0% N1.And they do not only behave differently on the real NG, it also sounds differently (how the engines behave not the actual sound).

MDG, this is something you should take a good look on, and change for the next fix/service pack. In my opinion this is the only bad thing about the 737NGX, although not too bad... just a minor detail, but important in my opinion.The rest of the NGX is great!Apart from the S-turns at cruise after a sudden change in wind direction...

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Wow, I'm always extremly sceptical by comparing an add-on to some random video. Even at HD you can't even read the exact reading for sure. Not sure what you mean with the sounds either. They've been pitch adjusted every ten percent of thrust so that should really be spot on. But you have a point in general, the engines do have a number of quirks (IMHO, as always), of which I already posted some to Ryan. They could need some improvement here and there, simulation wise. sig.gif

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Indeed, you can not see the exact numbers, but you can see that they accelerate really fast after 30% N1, and immediately establish at 40%. Way different then on the NGX.And yes, the pitch of the sound is very spot on indeed. But the behaviour and dynamics of the engine don't sound like the real ones.

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Indeed, you can not see the exact numbers, but you can see that they accelerate really fast after 30% N1, and immediately establish at 40%. Way different then on the NGX.And yes, the pitch of the sound is very spot on indeed. But the behaviour and dynamics of the engine don't sound like the real ones.Arjen V.
geez this is a sim not the real thing if u can make the real thing into a sim go ahead and try like to see how u do

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I can't, but PMDG can. Because they can simulate pretty much everything. So also this. Go ahead PMDG.

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Indeed, you can not see the exact numbers, but you can see that they accelerate really fast after 30% N1, and immediately establish at 40%. Way different then on the NGX.And yes, the pitch of the sound is very spot on indeed. But the behaviour and dynamics of the engine don't sound like the real ones.Arjen V.
From that video, are you able to tell the outside air temperature and the fuel temperature, then crossed referenced that with the same conditions in FSX? Point being, there are variables that will effect things like spool up time, all of which I'm sure PMDG have simulated. Absolutely pointless to pluck random videos from youtube and announce that they've modelled something incorrectly. Perhaps if you can come up with some hard figures from official documentation, people will take you seriously.

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I have also seen it myself! When is was in the cockpit of a Boeing 737-800WL from Transavia. The outside air tempature at the moment was about 20 C. When I put 20 C in FSX, the engines don't behave the same. Maybe it's something with the fuel tempature as you said, but I don't know what influences the fuel temp. And every takeoff I've been on the the 737. The engine's behaviour and dynamics sounded way different then on the NGX. in the same tempature as in FSX.Ryan, maybe you can explain this to me, (or us) ?Thanks in advance

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Every single CFM-56-7B will have a different spool up rate through mechanical imperfections, age, ambient conditions, accessory gearbox resistance, fuel filter cleanliness, bleed air demand, bleed air valve movement, pressurization rate of the labrinth seals, oil temperature, oil condition, fan blade condition, position and depth of fan blade chips/dents. The bottom line is, two engines on the average NG will spool up at different rates. at least initially, which is exactly why boeing do not assure symmetrical acceleration below around 40% N1, there after they assure it will be close*You can't call it badly modeled when its a variable in real life.

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how do you normally spool up to a given N1 %? I move the thrust levers forward....is there another way?

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Oh yeah, one more point, After pressing TOGA, the spool up rate depends on whether the pilot 'pushes' the throttles forward or lets the autothrottle advance the thrust levers at the preset rate. If the pilot pushes the levers forward quicker than the autothrottle rate, the engines accelerate at the rate of pilot input.Hope this helpsTawanda

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I have also seen it myself! When is was in the cockpit of a Boeing 737-800WL from Transavia. The outside air tempature at the moment was about 20 C. When I put 20 C in FSX, the engines don't behave the same. Maybe it's something with the fuel tempature as you said, but I don't know what influences the fuel temp. And every takeoff I've been on the the 737. The engine's behaviour and dynamics sounded way different then on the NGX. in the same tempature as in FSX.Ryan, maybe you can explain this to me, (or us) ? Thanks in advance
What is there to explain? You have taken a personal experience and believe you have observed a different behaviour from the simulated aircraft. You haven't accounted for (as far as i can see) a single variable that may affect both the simulator and the real aircraft. PMDG had real 737 pilots on the team when developed; i don't wish to doubt your knowledge, but i guess people who do this day in and out will know slightly more than a person who occasionally gets to sit in the cockpit?

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I can't, but PMDG can. Because they can simulate pretty much everything. So also this. Go ahead PMDG. Arjen Vandervelde
As much research as they've done, and as closely as they've worked with Boeing, if it CAN be done, they did. That's not likely to change because of a youtube video.

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When you put in 70 N1, you can wait at least ten seconds to reach 70.0% N1.
I just checked, on takeoff, from idle to 70% N1 took 5 seconds. 27 C outside temp.

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I just checked, on takeoff, from idle to 70% N1 took 5 seconds. 27 C outside temp.
I was talking about the 747 there. i'm talking about the N1 percentages before TO/GA. On the 747X the engines just don't want to establish. Way different on the real plane. On the 737NG it's 40% N1 before TO/GA. Now put it in, and it takes very long for the engines to reach 40.0% N1 and fully establish. From about 50% N1 and higher, the dynamics have been very well simulated. Fast acceleration, fast establishing. But this fast acceleration should already start after about 30-35% N1. Then you guys can say that I'm wrong, just because of a Youtube video. But let me tell you this, I have pilot in my family, for KLM, my uncle. I asked him and he said I was right.all GE engines are very stable and accelerate really fast after a certain percentage of N1. In the 737 it's 30%. in the 747 it's 50%, same for the 777.That's just been simulated wrong.And you can say that real pilot tested the NGX, yes that's true. But maybe they didn't care about that detail, or maybe they thought it wasn't that important. Arjen Vandervelde

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I hope you know that in the video the pilots pushed the throttle faster than the TOGA does. Then gave it a "boost".

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It seems no one is understanding what I mean. I said after 50% N1 acceleration and establishing is OK and very realistic. But that should already start after 30% N1. When the pilots in the video put the throttle levers to 40% N1, that didn't give it a boost.Until 30% N1, the engines accelerated really slowly, just like in the NGX. But then suddenly at 30%, boom! Fast acceleration and immediate establishing at 40% N1, while the NGX's engines continue to accelerate really slowly and don't want to establish, no matter what the outside air tempature is.Arjen Vandervelde

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OK I think I'm on the same page as you now. After testing, you might be on to something after all as it does appear to take a very, very long time for the engines to spool from ground idle to 40% N1 stable. It's obvious that PMDG had a hard time overcoming FSX limitations with regards to the engine modelling, so this is probably as accurate as it's going to get. It may just as easily be exactly the right duration of course, I don't know. Other than that, it may be hardware related as I know I've encountered several problems due to FSUIPC so far.

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I know that because I've been on the 737 many times, in the front, so I could hear it.
Lol. Sorry. Do what now?
Apart from the S-turns at cruise after a sudden change in wind direction...
I'm sure that you're aware(with your extreme taste for detail) that there is a workaround to this!

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I was talking about the 747 there. i'm talking about the N1 percentages before TO/GA. On the 747X the engines just don't want to establish. Way different on the real plane. On the 737NG it's 40% N1 before TO/GA. Now put it in, and it takes very long for the engines to reach 40.0% N1 and fully establish. From about 50% N1 and higher, the dynamics have been very well simulated. Fast acceleration, fast establishing. But this fast acceleration should already start after about 30-35% N1. Then you guys can say that I'm wrong, just because of a Youtube video. But let me tell you this, I have pilot in my family, for KLM, my uncle. I asked him and he said I was right.all GE engines are very stable and accelerate really fast after a certain percentage of N1. In the 737 it's 30%. in the 747 it's 50%, same for the 777.That's just been simulated wrong.And you can say that real pilot tested the NGX, yes that's true. But maybe they didn't care about that detail, or maybe they thought it wasn't that important. Arjen Vandervelde
I have a friend of my brother's wife, who happens to be my step mother's sister's niece who told me just the opposite. But hey what does she know considering she is in the know.

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One flight on a Transavia 737-800 is hardly what I call an adequate sample size. Trevor
ONE flight in the cockpit, and another 10 flight of KLM and Transavia in the cabin.I'm still waiting for Ryan to read this and reply.

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ONE flight in the cockpit, and another 10 flight of KLM and Transavia in the cabin. I'm still waiting for Ryan to read this and reply.
I've tried but still can't manage to see the N1 readout from the cabin. Those darn cockpit doors!Trevor

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Ryanair now have over 300 737NG's and I have flown at least 20 of those. They all sound different !! Frederic.

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