FedEx (PMDG)MD-11 and real weather

[skwaL 36]

I have looked @ US weather charts, all flight @ FL370 will get an avarage of -49C to -53C. So how is the MD-11 JET A, able to fly in those temperatures? My fuel lines keep freezing, and I watch real life flight just take place, and it flew @ avarage of -53C FL370.Ideas?My PMDG MD-11 Fuel keeps freezing, because of low temperature.

[scott967 62]

I think in winter you are supposed to use Jet A-1, but even for that it is cold. These scenarios were looked at quite a bit with the BA038 B777 that crashed just short of the runway. Keep in mind that it takes a while for the fuel in the tanks to chill to the outside air temp.scott s..

[KevinAu 441]

Also there are icing inhibitors that can be added to the fuel. Before entering the engines, the fuel will also have been through a heat exchanger that will have warmed them up a bit. The aircraft will also have minimum temperature limits for both the fuel tanks and outside. If temps start going below those limits, one can always descend into warmer air.

[WAD3 0]

I have found this to be a constant problem with the MD11. Last year when it came out it was winter and I ran into that all the time. A couple of times it ended in disaster for me. I learned to change the fuel to Jet B in the FMC and that gave me a freeze temp to -50. Still had to fly at a lower level than flights I could follow on Flightaware. Maybe it is something that happens in Flight sim and there is no way around. Still makes me wonder how it works in the real world.

[phil747fan 14]

go faster and lower that the rules ...

[Peter Clemenko 0]

What doesn't the PMDG model the fuel correctly?

[Orlaam 306]

go faster and lower that the rules ...

Kinda hard to go faster when you can't maintain the correct speeds to begin with. This thread suggests something is wrong with the envelope or speed variables in the MD: http://forums1.avsim.net/index.php?showtop...mp;hl=overspeedI can verify since all I fly are short routes, that the Mmo will drop instantly at some point, either dependent on weight or altitude, and the AP won't correct for this problem, thus putting you into an overspeed situation. On every flight I do, I have watch the Mmo drop down and manually correct for it by entering lower speeds into the FMS or keeping my cost index really low.Unfortunately, just like the EVM typo, thrust washout, and couple other bugs, the MD-11 didn't draw enough sales for PMDG to feel they need to update those lingering issues, so most of them are ignored or passed off as weather related.

[NathanX 2]

Kinda hard to go faster when you can't maintain the correct speeds to begin with. This thread suggests something is wrong with the envelope or speed variables in the MD: http://forums1.avsim.net/index.php?showtop...mp;hl=overspeedI can verify since all I fly are short routes, that the Mmo will drop instantly at some point, either dependent on weight or altitude, and the AP won't correct for this problem, thus putting you into an overspeed situation. On every flight I do, I have watch the Mmo drop down and manually correct for it by entering lower speeds into the FMS or keeping my cost index really low.Unfortunately, just like the EVM typo, thrust washout, and couple other bugs, the MD-11 didn't draw enough sales for PMDG to feel they need to update those lingering issues, so most of them are ignored or passed off as weather related.

Same here. I always blamed ASA so i did a flight without any weather, Takeoff GW 474600LB at approx. 457100lbs this anomaly happens. Doesn't matter what altitude. MMO drops, mach speed of .841 was decreased to .832 and after bleeding off more GW the mach speed continues to decreases. Autopilot will not correct for it and even speed intervention won't overcome it.P.S This is in FSX.

[Orlaam 306]

Same here. I always blamed ASA so i did a flight without any weather, Takeoff GW 474600LB at approx. 457100lbs this anomaly happens. Doesn't matter what altitude. MMO drops, mach speed of .841 was decreased to .832 and after bleeding off more GW the mach speed continues to decreases. Autopilot will not correct for it and even speed intervention won't overcome it.P.S This is in FSX.

Yeah, there are a few oddities with this plane and it's a shame. Apparently someone discovered that the thrust decreases on takeoff roll, so that is a problem, yet I can't say it affects any of my flights. However, this issue with the speed not working correctly, in my opinion, is a major problem. It's been stated that the plane won't achieve fast enough speeds that some say is due to the GW dropping below a certain point. This might be the case, however, several people have claimed the speed you can achieve in the real plane, even at this lower GW, should be much higher. Unfortunately, PMDG wasn't allowed to give us the proper spec sheets to confirm these speeds and weights and I don't know how to obtain that info. I do know that something is wrong when you are flying at say .830 and within a second the Mmo marker drops 10-20 knots down without warning putting the plane into an overspeed condition. It will then continue to drop down until you start your descent. No other plane I've ever had, including the PMDG 747 does anything like this, and we all know it isn't realistic. If the Mmo limit drops, it does so slowly and the FMC/FMS and AP compensate for it by keeping you well below the "red line", and the MD-11 doesn't follow this rule at all. For me, I've seen the Vmo and Mmo marker jump all over in certain cases, like it has no idea what to do. There is a serious problem with this aspect of the plane and it makes speed management, at least on short hauls impossible on a lot of flights. I shouldn't have to watch the speed tape like a hawk and be prepared to override the FMS SPD to avoid an overspeed. And I'm sorry, this isn't a Wx-related problem either.Then of course, the simplest fix of all, the typo of EMV on the secondary engine display. It should read EVM, not EMV. That would take a few minutes to fix. Now we have people with fuel freezing problems. I'm glad PMDG added this feature, but it obviously doesn't work right. It may or may not have to do with Wx add ons, but some say the temps they're getting are normal and the fuel still freezes. Obviously, the temperature change rate is too fast in the PMDG. Again, there are other bugs that some have commented on and they're kind of serious too, but you need to know the plane really well to notice them. I'm just very disappointed that PMDG won't acknowledge or address them, and when they do, they pass them all off on 3rd part Wx apps. We've been told an update is pretty much out of the question, so I'm not that happy. I just don't understand why these few fixes can't be addressed. I just think the MD-11 was a poor seller, so they don't care. It's obvious when you still see tons of 747 topics and hardly any MD-11 topics being created. I'm just surprised that the people who are passionate about the MD and raised these issues months ago gave up asking for updates. Why?Btw, I'm running mine in FS9

[JSkorna 137]

OM gosh! It wasn't ASA causing these problems all along???