Manual Slat Actuation Does Nothing

[EvilKipper]

Visually the slats move when manually actuated, but flight characteristics don't change at all. E.G. I can fully extend the slats at mach 2.2 and nothing bad happens.

[Azrayen]

Well, what should happen?

[EvilKipper]

Just from first principals, at mach 2.2, lowering the slats should result in any number of very bad outcomes.

 

1. Departure of the airplane from controlled flight

2. Failure of structure of the wing

3. Failure of the structure of the slats

 

I obviously don't know what would actually happen. Maybe it's never even been done. Maybe the FCS won't let you do it even with the switch. But at that speed, if you flip the switch, and they actually fully extend, I very much doubt nothing happens.

 

My suspicion is that probably whatever actuates them isn't strong enough to force them out at that speed. If that's true, then the animation is wrong. Still as it now I can force them out at 200 kts and then accelerate to mach 2.2. That is wrong, there should be more drag when they are out. I think the flight model, and the animation are just completely disconnected.

Edited December 16, 2017 by EvilKipper

[JefCostello]

Hi guys!

I'm not sure at all that if you try to extend slats at high speeds on the real plane, anything happens. Usually on planes with slats, there is a protection in the hydraulic circuit to avoid extension above speed limits of the slats(also flaps). I flew the DC10 as flight engineer, and during test flight after major overhaul, this is something we have to check, I mean retraction of slats above their speed limit. Of course DC10 is not a Mirage but I'm pretty sure this feature exist also on fighters.

 

Cheers

 

Jef

[jojo]

Just a side not about the Mirage 2000 SLATS.

 

Their purpose is to energize the wing when you take AoA to increase turn performances. These are sealed SLATs and when you increase AoA they actually decrease the drag.

This is way in normal landing the SLATS are retracted and extended only in case of engine power loss.

 

So it isn't exactly the same device as common air liners.

[JefCostello]

Just a side not about the Mirage 2000 SLATS.

 

Their purpose is to energize the wing when you take AoA to increase turn performances. These are sealed SLATs and when you increase AoA they actually decrease the drag.

This is way in normal landing the SLATS are retracted and extended only in case of engine power loss.

 

So it isn't exactly the same device as common air liners.

Hum! Are you sure slats are retracted for landing with an AoA of 14 degrees ? On the Airliners (I'm talking here of the DC10)yes slats are sloted(on the Mirage they are not sloted because they only act to increase the camber of the wing)and their function is to increase lift at low speed and they also have an"autoslats"function(in a certain flight enveloppe)in case on sudden AoA increase.

To bbrz

In the DC10 too you can select "slats extend"but nothing should happen because the air pressure on the slats is not enough to extend them, there is a blow back security on the slats hydraulic line.

To be back to the topic, if someone has a schematic with the description of the circuit we should know if it's possible to extend the slats by the switch at any speed which I doubt.

Regards

Jef

[myHelljumper]

Hum! Are you sure slats are retracted for landing with an AoA of 14 degrees ?

 

You can watch any M2000 landing video ;).

[jojo]

Hum! Are you sure slats are retracted for landing with an AoA of 14 degrees ?

Jef

 

p50

 

Train sorti, les becs sont automatiquement rentrés

http://www.avialogs.com/viewer/avialogs-documentviewer.php?id=1879

 

 

On landing they are using the wings drag as air brake. The SLATs would lead to too flat approach.

 

So on landing:

- don't use air brake, it will destroy lift rather than increasing drag.

- SLATs in unless you have suffer from engine power loss.