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Guest 747lover

MD11 handling

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Guest 747lover

I have a question regarding your MD11 which seems to be in the final stages of devolopment.The MD11 had it,s handling problems in the approach phase of flight.I think it was due to the combination of a trim tank and small tailplane which maked it unstable in the pitch axis.The aircraft was also unforgiving in x wind situation.MD did some software modifications which made it better regarding the stability in pitch.Does PMDG simulate the new or the old versions of the plane before the modification?Personally I hope for the old version because what we need in the FS community is a very difficult to handle beast which realy can test your handling skills.Ola NielsenNorway

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Totally agree with you sir,we need that kind of planeBut even with the new software, I think the handling should be quite special on approach in ergards of stability (we can see an example of this in the martinair MD-11 video where the pilot make a lot of inputs to the controls to keep the plane on the approach path)Deniz

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>Personally I hope for the old version because what we need in>the FS community is a very difficult to handle beast which>realy can test your handling skills.Ola,we model the MD-11 as it is flown presently. The earlier versions would be quite difficult to model, simply because there's no way for anyone to verify anything - the simulators and aircraft in service have no way to let us check earlier software versions.>But even with the new software, I think the handling should be quite special on approach >in ergards of stability (we can see an example of this in the martinair MD-11 video where>the pilot make a lot of inputs to the controls to keep the plane on the approach path)Deniz,what you see on that DVD has nothing to do with any handling qualities of the MD-11. There are gusting winds on that approach, as simple as that. Flight control movements like that can happen on ANY aircraft. Basically on approach the MD-11 is as stable as any aircraft. And should there be gusting wind I still prefer an MD-11 over a FBW Airbus because of the 'pilot-induced oscillation' problem on the latter.The MD-11 does have its flaws on approach/landing like the high speed or the pitch-up on touchdown...Regards,Markus


Markus Burkhard

 

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Ola - perhaps this is what you are referring to;From airlinesafefty.com (I think that the editor has put this in but you can get the gist of the conclusion). I do not know who to attribute this quote to but perhaps someone with direct MD11 experience can either confirm or deny whether this is really how an MD11 handles. It certainly seems to be the sort of challenge that youa re looking for.Quote"The MD-11 is not fly-by-wire. It is, however, fly by CONSTANT pilot input. The geniuses at MD decided to make the empennage 40% smaller than the DC-10 to save on both parasitic drag and induced drag by keeping the c.g.[center of gravity] near the aft limit during high-speed cruise.This airplane doesn't really have a "slot" when you are on final; it doesn't seem to really stay at a trimmed AOA [angle of attack] /deck angle at a specific power setting/airspeed. As such, the pilot is constantly making little corrections, like flying a dynamically unstable fly-by-wire fighter with the computer out. This is unlike any transport aircraft I've flown. Part of the problem is a system called the Longitudinal Stability Augmentation System (LSAS) which is a computer that constantly trims the stab to make up for the shortcomings of the tail size. The landing is also unique. As soon as the plane touches down I have to push on the yoke to counteract a severe pitchup from the spoilers coming to 2/3 extension. Less than a second later, the autobrakes kick in, so you have to pull back on the yoke to gently lower the nose to the runway"Gerry- sorry about the formatting or lack thereof.

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>QuoteWell it's obvious this quote is from someone who did not like the MD-11 at all given his all negative description. The sentence that the MD-11 flies like a FBW fighter with the computer out is of course complete nonsense. Markus


Markus Burkhard

 

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Guest D17S

I flew an MD11 sim at a Boeing flight training center a while back. I was somewhat amazed I was able to track LOC/GS with without much trouble. We left the AT engaged and after a little command bar chasing, it settled right down. I remember holding my hands up in the air and proudly announcing to the sim guy, "Hey look." He said "Very nice. Now look at this." as he failed the right engine.As we touched down, he reminded, "Now put the nose down." My sense was "Shouldn't we land first?" That high AOA on touch down had me completely disoriented. We (the cockpit) were still 50 feet in the air. Then we tried a one engine approach. His comment that time was "Get aggressive." As we slipped and crabbed our way down GS he finally reached over my shoulder and went stop to stop, just cranking inputs. We made it, but I was a bit startled how aggressive a pilot Can be, or even might NeeD to be with that airplane. I expect there will be pLentY of excitement even with this airplane as is. Try failing 2 engines (1/3 +2) at 500 feet. This is going to be fun.

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Just to add an interesting testimonial from a MD11 pilot about the handling :"Yeah the MD11 is a great bird, very powerful, and not the easiest bird to handle. For starters, really respect her and her systems. When alerts come, it's a hint that something may fail later on. The MD is stretched from the 10 and to meet the increased range and performance, they had to shrink the horizontal stabilizer or tailplane by 30%. Added to the fact it is predominantly to be flown in an aft CG configuration, longtidunial stability becomes a drag. No need to fear as the LSAS computer is here to assist us in trying to fly the bird like a normal plane. With no ground effect like the Jumbo Queen, it is hard to land, especially in a good crosswind. Even trying to get a nice landing on takes some work and takes time to feel out the plane (remember, the artifical feel from LSAS is helping us). Plus dont forget she has the higest Vref speeds in any other transport category aircraft so have to really watch those landing distances at max weight in those hot days!"BTW, thanks for the answer Markus :)Deniz

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This sounds like a fantastic aircraft to fly! :DI hope PMDG managed to get this feel into the sim. :)Best regards,Robin.

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