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davierosoft

AUTOSLAT feature, only a special effect or it changes dynamics?

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I was trying the autoslat system from outside view and internal view, the system seems to be working as expected, at least visually, but I've not see any tendency of the plane to increase lift after slat extension neither wing flex changes during/after extension. I did tests within few knots of speeds, in my configuration:-600-129-131kts (around 130kts triggered the autoslat)-flaps 1-11.6 AOA when slats extend to full position-Vertical speed controlled by AP in altitude hold.When stable at 130 with 11.6 of AOA, VS=0 lowering a bit the speed (just beginning to see the top of the 9) I get the autoslat working, AOA was still at 11.6, thrust was increased a bit to stabilize the speed, vertical speed remained stable.The only difference I found is that to stabilize speed I gave some thrust more than normal.Maybe the autoslat function gives only more drag on pmdg?This is the real (yes, it isn't NG): (Jump to minute 5.00)http://www.youtube.com/watch?v=a4V8W31YwTQIt is clearly visible tat aircraft reacts to the extension with increased lift (in the video there is also a bit of roll).Did the pmdg autoslat system was tested and compared with the real sim?

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as I understand the working principle of slats, those are NOT used to rise the lift directly. Though a minute increase might be a function of other aerodynamic change, that might or might not be specific to swept wing and/or NG wing specifically. Or it might really not happen at all and the percieved lift increase is just an illusion of roll.What slats are mainly for, at least on the cases I studied in my ground school, is to increase the critical AoA, thus allowing for lower speeds (and/or higher climb angle) since generally lift is a function of speed and AoA.I do not have NGX though yet as I just recently finally bought an FSX capable computer, so I can not try myself.

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Yeah, thats about it. Slats will not increase lift at a given AOA, they only prevent leading edge stall ( the worst kind) and increase the CsubLmax a little by themselves.Given the planform of most jets, they are an absolute necessity, though. All of these swept, pointy winged a/c would be deathtraps without them. For example, a snap roll on rotation by a DC9 at KDTW a few year ago attempting a no flaps (and therefore no slats) TO.ref. Abbott & von Doenhoff ( slat perf.)r

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As seen on the video, there is something that changes after extension. I'm not a pilot, but changing something on the wing (and we ar talking of most of the wing chord) will give a feedback in the cockpit, at least little AOA change, or a supposed little vertical speed increase.I know that the slats will change stall speed by lowering the stall speed, but extending them changes also the actual lift, if not too much, at least a bit.It is what I can see in the video after minute 5.

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I am sorry but I dont see any lift increase.Should you keep level flight, same power, slats will give you more drag and therefore slower speed and by extension, either you or autopilot holding level, higher AoA. I find slats rather effective slow-down device actually.

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I used AP to mantain altitude, manual thrust to mantain speed.I noticed only more drag, as it is needed more thrust to remain with same speed. No variation of AOA or change in vertical speed (that autopilot will fight changing AOA).To check if stall speed is different with or without autoslat I removed pressure from sys A & B to inhibit the autoslat function, but they still move without B pressure and without PTU (so without A system),it is then necessary to turn off buses to prevent autoslat function, but, as for the previous situation, due to flight control not working with no hyd pressure(a thing that I think must be fixed), it is almost impossible to mantain the speed, check autoslat operation, and do all the other things. I found that the slats without any AC main power retracts if previously (with AC) extended.Not an issue at all, like on other systems, tey are working as expected with normal conditions, obviously if we want to force to do something the answer may not be as we expect.

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To check the stall speed with Auto slat off you need to switch off hydraulic B for normal Auto slat operation, for the Alternate Autoslat operation Switch OFF the Hydraulic system A for the PTU (Power Transfer Unit). There is also a third Hydraulic system the Standby hydraulic system that also operates the LE Flap and slats and TE flaps. The Standby Hydraulic pump operates Automatically when these condition are true:* Either FLT CONTROL A or B switch to ON* ALTERNATE FLAPS arm switch to OFF* Trailing edge flaps not up* Airplane in the air or wheel speed more than 60 kts* Low flight control pressure.The Standby Hydraulic system only operates the LE slat to full extend. You are not able to retarct the LE Flap and slats with the Standby Hydraulic system. To check the Stall speeds without the autoslat and standby hydraulics set the FLIGHT CONTROL Switches A and B to OFF (not to STBY RUD) and switch off Hydraulic A and B. That is what the flight crew did on this video.

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Correct me if i'm wrong, but I heard that for FSX there is only 4 flaps (the ones on the default cessna) any other is just visuals.

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To check the stall speed with Auto slat off you need to switch off hydraulic B for normal Auto slat operation, for the Alternate Autoslat operation Switch OFF the Hydraulic system A for the PTU (Power Transfer Unit). There is also a third Hydraulic system the Standby hydraulic system that also operates the LE Flap and slats and TE flaps. The Standby Hydraulic pump operates Automatically when these condition are true:* Either FLT CONTROL A or B switch to ON* ALTERNATE FLAPS arm switch to OFF* Trailing edge flaps not up* Airplane in the air or wheel speed more than 60 kts* Low flight control pressure.The Standby Hydraulic system only operates the LE slat to full extend. You are not able to retarct the LE Flap and slats with the Standby Hydraulic system. To check the Stall speeds without the autoslat and standby hydraulics set the FLIGHT CONTROL Switches A and B to OFF (not to STBY RUD) and switch off Hydraulic A and B. That is what the flight crew did on this video.
-There is no automatic control for stby LE devices, the ALT FLAP switch must be on ARM to engage the pump and "down" must be set (28VDc) to open the stby LE shut off valve.-There is no automatic control for reverser operation, to operate reversers (w/o pressure) you need to activate the pump, the pump is started manually by either stby rudder switch position or alternate flap.-Stby pump starts automatically to operate for rudder in force fight situation or when a single (or both) flt cont pressure (in air) is low.There is no link on the autoslat system for Stby hydraulic.In the real aircraft te simplest way to disengage the system is to pull AUTOSLAT (DC and AC) circuit breakers, or, if you want to disable system B pressure, pull the PTU circuit breaker.PMDG is almost impossible to control without hyd pressure off or with both flt cont set to Off. Stby rudder automatic feature don't work, and manual operation is only avaiable with both flt cont switches to Stby rudder position. The strange thing is that the ligt for pump operation starts correctly.So, the tests are impossible to replicate on the ngx and the issue of slats retracting with no power on the plane is another thing that doesn't work.I'm thinking right now that I could replicate the autoslat operation using Alt flaps, if they works correctly.I can try both te differences between slats in (flaps up) and full, and bewteen mid (flaps 1) to full at a comfortable speed and without removing power to nothing.

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Tried to fully extend the slats in alternate mode witout extending flaps (just a click on the DOWN position)I must tell that PMDG did a great job on the alternate slat extension, time to extend them is close to the real, same for indication, perfect also the fact that you need to push down switch to extend them.Unfortunately, I tried it in cruise, with AP On, wen looking at overhead I opened the PFD and upper EICAS to check variations when extending.No changes in AOA, no changes in VS, neither spikes of VS, no changes in N1. I think it is only a visual effect as for the stall

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