WHY??? Cargo POSKY 744 sinks into runway at landing!!

[Guest creber1]

I don't understand this: I have made a picture-perfect approach just like I have done zillions before, no wind, touched down just at the perfect spot on the runway - and then this bird simply "sinks" in the ground, i.e. the rear wheels "eat" themselves into the concrete, making plenty of noise and firy and flashy flames (and thus the plane unsteerable)... why?? I have tried it with several of the POSKY 744Fs (Cargolux, Air France), at several airports, always the same problem.Anyone can help? Is the plane badly loaded, i.e. too much weight on the centre of the plane? If yes, can I influence this? Other reasons?

[Guest creber1]

I can make my question a little more precise: I am almost certain it has to do with the cargo having shifted during the flight. I just did the same approach (I had saved the situation before) with a pax 744, and the difference was: 1) much less trim!!! on the cargo plane, trim was almost max, to compensate for the cargo that had shifted towards the middle of the plane, and 2) it was a perfect landing....So, any hints on this?Cheers

[Guest groundpounder75]

Sounds like you are landing over weight. I use these models with the PSS 744 panel and I don't think I have seen this problem. I like to do long trips with the 744F so I burn off a lot of fuel before I land. Your landing weight should be no higher than 630,000lbs. I don't know what the real world 744F max landing weight is but try this for FS. This may be a factor and your descent rate may be a factor also, but it doesn't sound like it.

[Guest creber1]

Arthur,thanks for that. Indeed, I had a lot of fuel, 45% in the AUX and 100% in each of the mains, and that after having done KEWR-PANC, after all that is a 6h45min flight!! I had never bothered to do fuel planning, it never turned out to be a problem.Still, I now did the same landing, just manually changing the fuel load to 10% in the AUX and 20% in the mains. OK, the autopilot captured the glideslope much better than before - which was a welcome side-effect - but the plane still ate itself into the ground at touchdown. What worries me is that the trim was max and that for some reason cargo may have shifted during flight. Could that be the reason? If yes, how to controll either of these? I usually cruise on autopilot, so already reducing the trim is a difficulty on these big birds...Any idea?Cheers

[Guest groundpounder75]

Did you modify the aircraft.cfg file by any chance? What I am asking is if you have changed the contact points or any of the settings for them? Try unzipping the original file and "re-installing" the plane and try it again. I will take my Polar Air 744F out for a spin on Monday (tomorrow) and see if I have the same problem. I have never run into this issue."What worries me is that the trim was max and that for some reason cargo may have shifted during flight"Which way was the trim maxed out on? If the trim was all the way down then that would indicate to me that you have the plane loaded incorrectly. If the trim has to be all the way down to maintain a certain flight attitude then your CG may be in the wrong spot because the horizontal stabilizer has to develop enough taildown force to keep the nose at a pitch attitude. If the trim is at the max then the CG is to far forward and this would tell me your load is wrong. I don't know if I am looking to deep in to this or not???? From what you are telling me that is the conclusion I am drawing. Take out any load and do a quick flight with fuel and no cargo. See if it still happens. I will let you know what I find when I finish my flight. Hope I could help a little.

[Guest creber1]

Arthur, hey man, you are of incredible help... not taking the subject too deep at all!I have not made any changes to the aircraft.cfg (would not know how to do that anyways;-) ). On the trim: it was all to the max to prevent stalling. I guess that indicates that my takeoff/climb may have been a little steep (too low speed, not enough flaps, too high climb rate, etc), and/or, as you say, the load is bad. Forgive my ignorance: how can I take out load or shift load to other places on the plane to change the CG? That is in the aircraft.cfg file, right?By the way, wasn't there a reply post to my question where somebody commented on how he had shifted load around and that he would always take off with lots of flaps (15-20)? Where has that post gone???CheersCR

[Guest groundpounder75]

CR,Here is the deal as much as I understand it.....-First, which panel are you using? If you are using the stock MS panel then you should invest the $15 over at http://www.phoenix-simulation.co.uk/ and buy the base 747-400 panel and model. Then, you can merge the panel with the POSKY model. A very nice plane with the best 744 panel available right now. PSS is going to come out with a GMAX version and an updated panel soon so you may want to wait. This will give you a FMC-CDU that you can program your flight plan in to and use for vertical and lateral navigation. It will also calculate the correct V-speeds and Vref for landing all based on takeoff weights.-Next, procedures..... 1 - Flaps 10 or 20 depending on weight and runway length and temperature and whatever... I have seen some info from Atlas Air and they do all takeoffs with flaps 20 with their 744s.2 - Rotation speeds depend on weight and flap settings. More flaps, the lower the speeds will be but not much. If using MS panel, use the kneeboard info to get you by until you pick up the PSS panel. Advance throttles until 70% N1 and let engines stabilize. After they have stabilized engage TO/GA mode.3 - Rotate 8 degrees initially then gear up at positive rate of climb.4 - Pitch up to 15 - 18 degrees until 1500'. Climb out at 250 knots IAS below 10000'. Your nose attitude (pitch) will change your speed. The 744 climbs out at a power setting determined before takeoff. The pitch that you fly at will vary your speed at this power setting. At 1500' lower the nose a bit to accelerate(sp?) and retract flaps on schedule.5 - At 10000', pitch for 330 knots and climb to your initial cruise altitude.6 - On an ILS approach you want (from what I have read, anyone else please jump in) to intercept the localizer (crosswind leg) at flaps set to 10 degrees and at a speed of Vref + 20. Vref being the approach speed. When the glideslope becomes active and drops down one dot, set flaps to 20 and then drop the gear and run through the final descent check list. Approach the glideslope set your flaps to the landing setting, either 25 or 30 and set your Vref on the mode control panel. Also, arm the speed brake and set the autobrakes.7 - At about 50' AGL flare and set the 744 down on the runway. 8 - Apply reverse thrust and slow down.I think you maybe coming in to hard and fast. This plane is cool to fly but takes some practice and procedures to fly it correctly. Check this web site out for information...http://www.flightdeck747-436.20m.com/Send me your email address and I can send you some documentation I have on real procedures.

[scott967 62]

I'm no expert, but I d/led and took a look at the posky 744f polar air cargo. I also had the gear colapse on landing, but if I set it down ever so softly it would hold. Here's what I found:2 of the loads are messed up. It appears the designer was looking at the default MS 744 which has the ref point at the nose, but the posky has it at CG, 85 ft aft, so these two points are 83.5 feet too far back. The corrected values are:station_load.0=9720,-16.6, 0.0, -11.0Center2=-110.0, 0.0, 6.0, 3298.0, 3.0There is also this line:station_load.0=0.000000,0.000000,0.000000,0.000000which makes no sense and I deleted it.I looked at the gear. All the default aircraft have compression rations around 2 - 2.5, but these posky's have compression ratio in the range of .5 This makes no sense to me. I think it might be worth experimenting with different values closer to 2 and see what happens. Posky also uses a large wheel radius of 5 ft which is big, but I have seen other addon aircraft with big wheels. Not sure what developers are trying to achieve with this. I _do_ know you can get some bizzare ground handling if you fool with these values, so back up the original first and document as you go.scott s..

[Guest creber1]

Arthur, Scott,zillion thanks. Between Arthur's hints and the modifications scoss suggested I just did a couple of flights on several of the POSKY 744F (Cargolux, Polar, Air France Cargo) - landing was smooth like silk!THanks, I learned a lot (and I thought I already knew a lot;-) )CR