PMDG 747 question

I have no idea which bell or cricket it could be. Stall maybe? Check the manual, I'm sure it lists all sounds and their causes 🙂

You should put this qustion in their support forum. You should get an answer there.

That grinding noise does sound strange. The only thing I could think of is that the flaps were still notched and taking damage. That would make sense as to why you were losing speed in cruise, although the bird does climb fairly slowly. The 737 by them also had a sound for the trim wheel, so whenever the user or autopilot trimmed the aircraft, a rattling noise was heard in the cockpit. I don't remember hearing it in the 747, but it may have tagged along...

I'll take the plane up for a spin later today and see if I hear anything.

I am right now flying at 30,000ft because for some reason the plane can't even maintain 245 at 35,000ft. I got the plane up to 35,000ft by flying level for about 10 minutes then I got my speed high enough to climb 1,000ft after climbing 1,000ft my speed had dropped by about 20. so I had to wait another 10 minutes to get my speed back up again before going another 1,000ft. But once I got up around 34,000ft my speed was around 260 and it wasn't speeding up at all with the engines on full power.

Let's talk in terms of Mach numbers at cruise altitude as that will give us a better idea of the speed. For the PMDG, depending on cost index in the FMC, you should be anywhere from 0.84 mach up to 0.86 mach. If you have the flight computer set to V-Nav (and all of your weight/performance data entered), it should climb by that point at a rate of around 500fpm (sounds slow, but it is a fairly large plane to move!). If you are climbing by hand or using V/S, you may just be asking for more than the plane can give. Use either FL-CH or VNav to get up there, and you should be fine.

I have been flying now at 34,000ft. for 15 minutes now and my speed is around 251 and I have the autopilot on i'm trying to get it to maintain mach .83 but apparently it isn't even close to that number and the engines are on full power.

Well then whats your fuel load and payload at that altitude?

What's the comparisson between Mach numbers and knots? i.e. Does 0.84 mach = 500 knots?

i'm not sure what the conversion is, but since the air is thinner up there, your IAS gets thrown off a bit. Mach is much easier to set a standard in.

You must be either overloading the plane or have that notch of flaps down. Keep in mind, I flew a 12+ hour flight from SFO-ZBAA (beijing) in this plane a few weeks ago, 2/3 pax and cargo loaded (using the load manager provided), and only needed 285,000lbs of fuel to get there (if I had loaded much more, I would've used more and probably wouldn't have made it!). I also had to start my cruise at FL320, and step up every 1500-2000nm. Going from something like chicago to san-francisco you'll probably only use up around 80,000 lbs. and be able to hold FL380 or FL400. If you're loading more than you need, then the most efficient (as well as the MAXIMUM flight level the plane can get to) will be much lower. You can see these values in the manual. They have excellent tips on how to load the proper amount!

Also, be sure when loading the plane that you're loading fuel using the PMDG menu in flight. One of the options tabs has an area to load fuel using the PMDG module. If you load it by hand or using the standard "Fuel and Payload" option in FS, it's probably not being evenly distributed to the right spots. It's got tons of fuel tanks, and it can be quite tricky to load them properly!