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Guest ToMy Li

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Guest ToMy Li

Does PMDG will implement his first time the "Ground Effect" just for landing the 747-400? like a real heavy bird? LEVEL-D 767 has itThanks for PUBLISH my post,Regards, :-wave

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Guest mc.kar

To my knowledge MSFS (in any version) does not support simulating groundeffect. As far as I have seen there are not any variables concerning the flight model that would indicate the amount of ground effect that a certain aircraft has.I'm also quite surprised that you say that LD767 simulates ground effect. To me it doesn't seem that there are any form of ground effect in the LD767 - however I'm only a desktop aviator:-). But I would look for a slowly decreasin rate of descent when 10-20 ft. off the ground and honestly I dont see that. To mee it seems that the VVI goes straight to zero when the mains touch.I also did a quick search both in the LD767 manual as well as the forum for the phrase "ground effect" and I couldn't find any hits that indicated this is simulated.So...I think the answer is that this will probably not be simulated in the PMDG 747-400...nor is it simulated on the LD767. However I'm prepared to learn from others if they have information that will correct this :-)Best regards Michael

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>>Does PMDG will implement his first time the "Ground Effect">just for landing the 747-400? like a real heavy bird? LEVEL-D>767 has it>>>Thanks for PUBLISH my post,>Regards, :-wave >>Table 400 in the *.air file is for Ground Effect and interacts with table 404 to create ground effect. All aircraft in FS9 are capable of ground effect modeling.The only problem with a 744 is inertia. As an example, on a real 727 with an approach speed of around 130 knots and weighing 130,000 lbs, the initial rate of descent is 700 fpm. When ground effect is encountered at about 50 ft or so, this reduces to 400-500 fpm. The pilot still needs to flare or the landing will be heavy. Translate this into an aircraft that has max landing weights anywhere from 574,000 to 666,000 lbs and inertia plays a larger role than ground effect does. You would be lucky to even get a 50 fpm check in descent rate with a 744 due to ground effect. Maybe a bit better at lighter landing weights but inertia is king with the 744.Cheers,JohnBoeing 727/737 & Lockheed C-130/L-100 Mechanichttp://www.precisionmanuals.com/images/forum/ng_driver.jpg

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>When ground effect is encountered at about 50 ft or so,Ground effect at 50 ft :-hmmmI don't think so, even for something as big as 747. Ground effect can only occur when distance between the ground and the wing is comparable to wing's chord and as Michael correctly writes above for a 767-like aircraft that would be at about 20 feet max.Michael J.WinXP-Home SP2,AMD64 3500+,Abit AV8,Radeon X800Pro,36GB Raptor,1GB PC3200,Audigy 2


Michael J.

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Guest ToMy Li

mc.kar it's has been mentioned just 1 or 2 days before 767 LVD released, and if you try to just 10' or 15' feets with any other add-on like PMDG for example, the aircraft looks like a ball, try the same with the wonderful LEVEL-D... you will feel that difference :-erks

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>>When ground effect is encountered at about 50 ft or so,>>Ground effect at 50 ft :-hmmm>>I don't think so, even for something as big as 747. Ground>effect can only occur when distance between the ground and the>wing is comparable to wing's chord and as Michael correctly>writes above for a 767-like aircraft that would be at about 20>feet max.>>Michael J.>WinXP-Home SP2,AMD64 3500+,Abit AV8,Radeon X800Pro,36GB>Raptor,1GB PC3200,Audigy 2That's right, and I said encountered.... that would be when the wing starts to "FEEL" the ground effect and there is a noticeable decrease in virtical speed until about 15-20 ft at which point ground effect is at it's strongest and should be constant to touchdown. I've seen this personally in the 727.>Ground effect can only occur when distance between the ground and the>wing is comparable to wing's chord.This statement is only partially true in that full ground effect cannot be calculated on chord alone, be it MAC or true chord. Trailing edge flaps and leading edge devices will also contribute to how ground effect interacts with aircraft. Ground effect is not an exercise in simple arithmatic and a lot of trial and error is required to determine how ground effect interacts with each aircraft. cheers,JohnBoeing 727/737 & Lockheed C-130/L-100 Mechanichttp://www.precisionmanuals.com/images/forum/ng_driver.jpg

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sorry for the dumb question. but what is ground effect? dont know if this is right, but based on what i read on this post i guess its when the air gets trapped under the plane when its very low and kind of cusions the plane?adam

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Ground effect is basically a level of cushion of air caused by the relative airflow flowing over the wings hitting the ground and being deflected. As more flaps are deployed, there will be more ground effect because of the amount of downwash created by the angle of the trailing flaps. The 'cushion' to be more precise is actually a increase in total reaction and a decrease in induced drag which results in a "increase" vertical speed without power increase. Not only on hard surface, ground effect could also be found on water surfaces. This natural effect is used by many birds that migrates long distances over vast water bodies.Eien


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Guest sfflyer

Aircraft do work on a mass of air that is circular in cross-section and roughly equal to the span. Between the wingtip trailing vortices is a flow field of downwash and outside them a flow field of upwash. The energy contained within the total circulation system is that required to support the aircraft.Operating in ground effect alters the shape of the flow fields, but not the mass or magnitude - resulting in a spreading and squeezing of the flow, and causing the effects seen in ground effect.In general, ground effect becomes sensible within a span width of the ground, and becomes a significant factor in reducing drag due to lift (induced drag) when the wing is below 1/2 span above the surface.Wing location plays a role here, while chord is unimportant. A high wing aircraft may only see a 15-20% reduction in induced drag on landing or takeoff, while a low wing aircraft may see up to 60% reduction. On takeoff, flying out of ground effect results in an increase in angle of attack for a constant coefficient of lift, increase in induced drag and thrust required, decreased stability and nose up pitching moment, and reduction in static pressure with related increase in indicated airspeed. On landing, the effects are reversed, so decrease alpha, induced drag, thrust required, IAS, and increased stability, nose down pitching moment, static pressure.From an engineering point of view, ground effect increases effective span and effective aspect ratio, while reducing angle of attack, all resulting in a reduction in induced drag.Any good pilot training text (e.g., FAA-H-8083-3 Airplane Flying Handbook), aerodynamics text (Anderson is the clearest and IMO, the best of the lot...the fact that I studied under him in no way sways my thoughts on the subject), or aircraft design text (Stinton is accessible and does not carry the math to an excessive level) should cover the subject in more detail, and has the circulation theory diagrams to aid understanding.

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