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JLuis

You only have one chance...PMDG, Fenix or Maddog?

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6 hours ago, Chock said:

Although some systems on airliners can function without the INS having been aligned, a lot of them depend on the airliner 'knowing where it is', which is what the INS tells it. However, whilst the navigation systems on an airliner, and specifically the inertial navigation system, is constantly updated via cross-referencing the data it receives from many sources, including radio beacons, the primary source for that is GPS satellites, and since the initial data it gets for that is set up when you align the INS, you do really need that initial set up for things to work to their full capabilities.

The INS can take up to fifteen minutes to align. How long it actually takes depends on where you are on the planet when you do that, because what the INS does, is uses the movement detected by a set of ring laser gyros which detect the rotation of the Earth, when it combines this information with detection of the magnetic pole of the Earth's direction, it cross references these two bits of information, and that's how it learns where it is. As you probably know, the world spins around at 15 degrees per hour, but at the equator, you are spinning faster than you are when near the poles a bit like how you spin faster on a merry go round on a ride, whereas in the middle you are not spinning fast at all, which is why it takes less or more time for the aeroplane to suss out where it is for different locations because it is detecting that rotation rate.

After the aeroplane starts moving, it measures all the movements it is then making and it adds or subtracts that info from the starting point where it knew where it was when the system was aligned, and that's how the navigation systems can continue to know where the thing is, but with some errors this means that after a flight of several hours, it can be a bit 'off', which is why you might than realign the INS after a flight in preparation for another flight. Having said that, even the very earliest inertial reference systems, which used traditional gyroscopes rather than ring laser gyros and did not have the benefit of modern GPS signals, were still good enough for an airliner to perhaps only be maybe a mile or so 'out' after having flown across the Atlantic, by which time they could use radio beacons to update where they were, so it was not really a big deal although it is one of the reasons why airliner corridors over the Atlantic are several miles wide and set at different altitudes for opposite directions.

You might be interested to know that submarines do this stuff too, since when they are deep under the water, they cannot detect radio signals from a GPS, so they use an INS to know where they are. They can float a buoy on a wire up on the surface to update their system, or extend a long antenna from the conning tower, but in combat they would not want to do that since it would give away their position. In peacetime, they do periodically float their buoy to update their INS system. Back in WW1 and WW2, when there was no GPS, they would shoot their position with a sextant whilst surfaced, set their gyros from that, then use the gyros whilst submerged to continue to know where they were even when submerged, and even back then it was fairly accurate for a good few hours so long as they knew what the currents were, but unlike modern submarines which can stay underwater for weeks at a time and which are actually faster underwater than they are on the surface, WW1 and WW2 submarines were faster on the surface than when submerged, so they were mostly used as surface vessels which would only submerge to sneak in for an attack, thus it didn't matter that their inertial reference gyros were not good for extended periods.

All of this funky new ring laser INS stuff on modern airliners means they are very accurate, which is what all that 'RNP' stuff is about, but it is still the case that you do need them to be aligned prior to setting off or you will find your primary flight display screens will eventually just go black and display some text saying they have no data; so to align properly, you have to be parked up with the wheel brakes on to allow your aeroplane to figure out where it is. So the short answer is: Nope, you can't align the INS whilst moving. the crew of an ATR tried to do that once because they were rushing their pre-flight, and so they tried aligning the INS when taxying out for take off, sadly they were in a mountainous region in low cloud, and so they eventually struck a mountain side when they lost their nav systems shortly after take off whilst in low clouds. Similarly, a 737 took off once and also did not have its system aligned, meaning it too lost its primary flight displays not long after take off, but on that occasion it was daylight in clear weather and in reasonably flat terrain, and so they were able to return to the airport and land the thing using VFR.

Airports used to have the latitude and longitude position painted in big letters on the front of the stand so that crews could type that into their nav systems, and you can actually still do that with a modern INS and speed up the align process a bit by giving the systems a good 'starting point' for them to begin working out where they are, but you won't find many airports these days with that info painted on the head of the stand, so it is usually the case that the crews just let the system suss it out whilst they are on a turnaround. This is not normally an issue because even the fastest turnarounds for a 737 are about 25 minutes, and most of the time it will probably take maybe five minutes for an INS to align itself. Of course in the sim we can 'cheat' and use a 'fast align' option if we want to, which is why the PMDG 737 can be a 'jump in and go' option.

If you like using failures on your sim aeroplanes, this is one of the advantages of the 737, since you can tell the exact thrust settings by looking at the throttle lever positions, which is why it is a good idea to make a metal note of the positions of those levers for various phases of flight, so if you lose your displays, you can still estimate your speeds and use the standby artificial horizon to know your speed and AoA.

Thanks for all this information Chock, very interesting

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Like 90% of the population if I only had enough money to buy one I would buy whichever one is slightly cheaper than the rest.  Since the scenario is based on financial constraints to begin with.  That way I could use any remaining money for beer and/or pizza while I learn to start the thing up.

 


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These 3 addons are going so deep in their systems that it is nearly impossible to master one aircraft 100%, I mean only real pilots can pretend to know those aircrafts 100% and they study many years for that.

So I don't get how do you guys proceed if you buy them all (737,A320 and MD82)?

You fly them knowing that you don't know all about them? Isn't it a bit frustrating? And if so, why do you buy addons that are so expensive? No judgement, just a genuine question.

For myself, I know I would rather buy only one (the 737) and try to know it as deep as I can, like a real pilot, than try to remember 3 different procedures for each phase of a flight .

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1 hour ago, Noooch said:

These 3 addons are going so deep in their systems that it is nearly impossible to master one aircraft 100%, I mean only real pilots can pretend to know those aircrafts 100% and they study many years for that.

So I don't get how do you guys proceed if you buy them all (737,A320 and MD82)?

You fly them knowing that you don't know all about them? Isn't it a bit frustrating? And if so, why do you buy addons that are so expensive? No judgement, just a genuine question.

For myself, I know I would rather buy only one (the 737) and try to know it as deep as I can, like a real pilot, than try to remember 3 different procedures for each phase of a flight .

I doubt I will ever fully learn all the systems of the PMDG 737.  But the problem is, there is only one other competitor on the market for MSFS and that is the Bredok 737: https://youtu.be/83cXJr1Y9OE?t=62

You can see the cockpit textures and lighting look very off for the Bredok 737.  Having said that, I have read that the functionality of the systems of the Bredok from the reviews, is reasonable, given the price of it.  

I do plan to use MSFS for years and while I may not fully learn the PMDG 737 systems over that time, I think I can enjoy it over many years.  Having said that, I'm not going to pay over $100 for the PMDG 737.  I'm hoping the price will be under $70.  I guess we will see.

The best part is, MSFS has saved me a lot of money.  I don't have to pay for 3rd party add-ons to make it look good.  I don't have to pay for an extra hard drive to store ortho.  And I don't need a super computer to run MSFS.  All the money that I saved, I can now use on stuff like a PMDG 737.

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i5-12400, RTX 3060 Ti, 32 GB RAM

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I see my VR/stereoscopic 3D setup has been hiding just how hideous and low quality the Bredok 737's cockpit interior is.🤣

I swear VR/3D makes anything look somewhat nice.


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