737 max crosswind take-off roll. Question on rudder
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At the moment of liftoff the cross controls should be very close to, or exactly the same, as if you'd just landed in that configuration and speed.
There's a roll input that will allow the plane to lift off and naturally turn slighty into the wind. There's a corrseponding opposite rudder that will keep the a/c tracking straight.
It's one of the small joys, and times to observe your coworker's skill, to do a takeoff that has no side load as the a/c lightens during rotation, and does a nice blended roll into the desired track and control inputs are neutralized.
And this isn't a computer game. The wind isn't always the same during the 10(?) seconds to go from Vr to established in the correct track(heading) and the gear is commanded up. The slight variations in wind, and no one will have the inputs EXACTLY perfect everytime, will take very minor corrections that no passenger, hopefully, ever notices.
There's a roll input that will allow the plane to lift off and naturally turn slighty into the wind. There's a corrseponding opposite rudder that will keep the a/c tracking straight.
It's one of the small joys, and times to observe your coworker's skill, to do a takeoff that has no side load as the a/c lightens during rotation, and does a nice blended roll into the desired track and control inputs are neutralized.
And this isn't a computer game. The wind isn't always the same during the 10(?) seconds to go from Vr to established in the correct track(heading) and the gear is commanded up. The slight variations in wind, and no one will have the inputs EXACTLY perfect everytime, will take very minor corrections that no passenger, hopefully, ever notices.
I have never understood the concern with 'spoiler drag' on take off.
It is far more important to keep the wings level throughout the take off roll and ensuing rotation than worrying about the comparitively negligible drag of raised flight spoilers on the upwind wing.
There will be a lot more drag produced if you start skidding downwind, and / or off the runway because you are not using the right technique.
Keeping the wings level, nose and main wheels planted firmly on the ground until VR then rotating with wings level using whatever control wheel inputs are necessary is paramount.
It is far more important to keep the wings level throughout the take off roll and ensuing rotation than worrying about the comparitively negligible drag of raised flight spoilers on the upwind wing.
There will be a lot more drag produced if you start skidding downwind, and / or off the runway because you are not using the right technique.
Keeping the wings level, nose and main wheels planted firmly on the ground until VR then rotating with wings level using whatever control wheel inputs are necessary is paramount.
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Hands up all those who remember their first attempts at crosswind take off's in Cessna 172, Warriors and even Tiger Moths and their ilk where junior instructors and some senior instructors too, insist on full control wheel (stick in the Moth) deflection into any crosswind, be it five knots or 15 knots. Aileron into wind, Bloggs... I sometimes wonder if those bad habits die hard and are carried over years later into jet transports.
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Stilton - More important to keep the wings level? How much does the plane roll downwind on takeoff roll if no input is made? Half a degree? One degree? And for that guys are putting spoilers up before it's even required? Boeing has described the procedure they used to generate the takeoff performance.
If you're anywhere near balanced field length, and having multiple thrust settings and assumed power takeoffs creates that situation, what is your takeoff distance if you artificially increase your drag during the takeoff roll?
Necessary technique/procedure for light airplanes? Absolutely. Jets? No.
If you're anywhere near balanced field length, and having multiple thrust settings and assumed power takeoffs creates that situation, what is your takeoff distance if you artificially increase your drag during the takeoff roll?
Necessary technique/procedure for light airplanes? Absolutely. Jets? No.
misd-agin, you obviously missed again.
Try re reading my post and thinking about it a little more.
Not applying corrective crosswind inputs will cause you a lot more directional problems creating more drag than the negligible drag of partially raised spoilers on one wing.
The drag is negligible, what you are actually doing with these raised spoilers is keeping the main gear firmly planted throughout the take off roll, this is important !
The spoilers are killing lift where you do not want it, they have a very minimal affect on acceleration or deceleration at these speeds.
Try re reading my post and thinking about it a little more.
Not applying corrective crosswind inputs will cause you a lot more directional problems creating more drag than the negligible drag of partially raised spoilers on one wing.
The drag is negligible, what you are actually doing with these raised spoilers is keeping the main gear firmly planted throughout the take off roll, this is important !
The spoilers are killing lift where you do not want it, they have a very minimal affect on acceleration or deceleration at these speeds.
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So now you're speaking highly about generating downforce, by killing lift with the spoiler, to keep the main gear forced into the ground, during the takeoff roll???
The spoilers are killing lift where we do not want it? Where do we NOT want lift during the takeoff roll?
The spoilers are killing lift where we do not want it? Where do we NOT want lift during the takeoff roll?
'So now you're speaking highly about generating downforce, by killing lift with the spoiler, to keep the main gear forced into the ground, during the takeoff roll??? '
You may remember the reason we hold into wind Aileron on a crosswind take off is to prevent the upwind wing from lifting, when we do not want it to, both during the take off roll and subsequent rotation.
With stronger winds the Aileron deflection required will cause differential deflection of the flight spoilers on the upwind wing, this will kill some of the lift on this side, there is nothing wrong with this during the take off roll as we are not attempting to fly before VR at least we shouldn't be.
'The spoilers are killing lift where we do not want it? Where do we NOT want lift during the takeoff roll? '
On the upwind wing before and during rotation, basically we want less than too much !
Do you really want to fly before that point ?
You may remember the reason we hold into wind Aileron on a crosswind take off is to prevent the upwind wing from lifting, when we do not want it to, both during the take off roll and subsequent rotation.
With stronger winds the Aileron deflection required will cause differential deflection of the flight spoilers on the upwind wing, this will kill some of the lift on this side, there is nothing wrong with this during the take off roll as we are not attempting to fly before VR at least we shouldn't be.
'The spoilers are killing lift where we do not want it? Where do we NOT want lift during the takeoff roll? '
On the upwind wing before and during rotation, basically we want less than too much !
Do you really want to fly before that point ?
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Boeing says to use the amount necessary to keep the wings level.
There's no attempt to drive the main gear into the ground. The intent is to maintain wings level. The amount of roll input at the start of the takeoff roll is zero. At rotation it should be about the same amount you'd have if you had just landed.
Maybe we're talking about the same thing and just missing each other's intent.
There's no attempt to drive the main gear into the ground. The intent is to maintain wings level. The amount of roll input at the start of the takeoff roll is zero. At rotation it should be about the same amount you'd have if you had just landed.
Maybe we're talking about the same thing and just missing each other's intent.
