Spoilers and Jet Upset
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Spoilers and Jet Upset
A few more questions:
1. Regarding spoilers. Do they have any limitations? What is spoiler blowback?
2. What is jet upset and how do you recover?
Thanks for the info.
YHZ Pilot
1. Regarding spoilers. Do they have any limitations? What is spoiler blowback?
2. What is jet upset and how do you recover?
Thanks for the info.
YHZ Pilot
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With regards to your first question, what specific aircraft are you interested in?
As for your second one, you know how Airbuses start calling you names at about 20' AGL? That's a jet that's upset at you.
As for your second one, you know how Airbuses start calling you names at about 20' AGL? That's a jet that's upset at you.
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As applicable to B744
YHZ,
Spoiler limitations: The B744 does not recommend using spoilers with greater than flaps 10 or 20 (depending on manufacture/mod status) due to the spoiler turbulence causing cracking in the flap tracks. At the higher flap settings, there already is a lot of stress on the flap assembly (AFM note not to use for extended periods), and spoilers add extra stress to the system. Also, after flap 20 extra drag is available with gear down. If you did select flap >20 plus gear plus spoiler you would virtually fall out of the sky and potentially kiss the earth with a hard smack (as well as cracking flap tracks).
"Jet upset" is basically an "unusual attitude", but especially one at a high altitude (where there is little thrust margin, and little margin between high and low speed buffet). It can be caused by thunderstorms/CAT, autopilot/trim malfunction etc. Recovery is standard. Oh, just keep in mind that underslung jets tend to pitch you up when you add thrust and vice versa.
Spoiler limitations: The B744 does not recommend using spoilers with greater than flaps 10 or 20 (depending on manufacture/mod status) due to the spoiler turbulence causing cracking in the flap tracks. At the higher flap settings, there already is a lot of stress on the flap assembly (AFM note not to use for extended periods), and spoilers add extra stress to the system. Also, after flap 20 extra drag is available with gear down. If you did select flap >20 plus gear plus spoiler you would virtually fall out of the sky and potentially kiss the earth with a hard smack (as well as cracking flap tracks).
"Jet upset" is basically an "unusual attitude", but especially one at a high altitude (where there is little thrust margin, and little margin between high and low speed buffet). It can be caused by thunderstorms/CAT, autopilot/trim malfunction etc. Recovery is standard. Oh, just keep in mind that underslung jets tend to pitch you up when you add thrust and vice versa.
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Spoiler limitations: The B744 does not recommend using spoilers with greater than flaps 10 or 20 (depending on manufacture/mod status) due to the spoiler turbulence causing cracking in the flap tracks. At the higher flap settings, there already is a lot of stress on the flap assembly (AFM note not to use for extended periods), and spoilers add extra stress to the system. Also, after flap 20 extra drag is available with gear down. If you did select flap >20 plus gear plus spoiler you would virtually fall out of the sky and potentially kiss the earth with a hard smack (as well as cracking flap tracks).
744 Spoilers go up and down as the result of a control wheel input and has no bearing on flap position. From memory 744 have a "blow down" valve in the spoiler actuator that lets the spoiler be pushed down from air loads should the pressure inside the actuator exceeds 4000 psi.
Speed brakes on the 744 do operate differently depending on the aircraft config and may have limitations in flight but I would not know as I only fix them......
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I always thought it was bad form to use speedbrakes with any flap selected on any Boeing type, thus the norm of using the gear if one is in that situation!
Yes, yes, I am aware that the spoilers are used as roll augmentation as a normal part of flight control, but independent of this intentional speedbrake selection.
And yes, spoiler blow-down at high speed is the norm also.
Cheers, FD
Yes, yes, I am aware that the spoilers are used as roll augmentation as a normal part of flight control, but independent of this intentional speedbrake selection.
And yes, spoiler blow-down at high speed is the norm also.
Cheers, FD
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YHZ Pilot;
In response to you question on spoiler blowback: There is a speed that if the spoilers/speedbrakes were to be deployed the amount of hydraulic pressure is not great enouth to allow full panel deployment. This point called "blowdown" is not the same for all aircraft and not even the same for all the spoilers/speedbrakes an the same aircraft, as the panels very in size as do the size of the actuators/pistons.
In response to you question on spoiler blowback: There is a speed that if the spoilers/speedbrakes were to be deployed the amount of hydraulic pressure is not great enouth to allow full panel deployment. This point called "blowdown" is not the same for all aircraft and not even the same for all the spoilers/speedbrakes an the same aircraft, as the panels very in size as do the size of the actuators/pistons.
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I always thought it was bad form to use speedbrakes with any flap selected on any Boeing type, thus the norm of using the gear if one is in that situation!
PP
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You can't win.. Boeing's tell you to 'don't think' and airbuses call you a retard...
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On the CRJ, there are four sets of spoiler panels, named from the inside out:
2 sets Ground Spoilers (Lift Dumpers)
Flight Spoilers (Speed Brakes)
Spoilerons
All four sets deploy on landing, but only the outer 2 sets are active in the air. Use of the word speedbrake is discouraged and "Flight Spoilers (FS)" encouraged.
Only limitation for FS use is Vref+17 kts and they have to be stowed by 300' AGL on approach. Blowback is a function of speed and hyd pressure and you can normally see about 5 degrees less than full (50 degrees) at 300KIAS with full FS selected. As speed bleeds off below 280KIAS, the FS indication is at full.
2 sets Ground Spoilers (Lift Dumpers)
Flight Spoilers (Speed Brakes)
Spoilerons
All four sets deploy on landing, but only the outer 2 sets are active in the air. Use of the word speedbrake is discouraged and "Flight Spoilers (FS)" encouraged.
Only limitation for FS use is Vref+17 kts and they have to be stowed by 300' AGL on approach. Blowback is a function of speed and hyd pressure and you can normally see about 5 degrees less than full (50 degrees) at 300KIAS with full FS selected. As speed bleeds off below 280KIAS, the FS indication is at full.
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Thanks for the explanation. Can I assume that flight spoilers are activated automatically, as I often see them operate during turns, even very shortly after TO when we can't be much more than 1000 feet up?
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Can I assume that flight spoilers are activated automatically, as I often see them operate during turns, even very shortly after TO when we can't be much more than 1000 feet up?
Roll Augmentation, with most jet aircraft, flaps retracted or extended...except for the L1011, with this aircraft spoiler roll augmentation is applicable with flaps extended only. With flaps fully retracted on the L1011, both inboard and outboard ailerons are active, no spoiler roll augmentation.
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YHZ Pilot
To have better info about Jet Upset try this link http://www.smartcockpit.com/pdf/flig...ingtechnique/4
Bye
H. C
To have better info about Jet Upset try this link http://www.smartcockpit.com/pdf/flig...ingtechnique/4
Bye
H. C
