Crosswind Takeoff overcontrol?

[CecilRooseveltHooks]

Dear Pros,

Does this make you as nervous to watch as me? I would not want to be a passenger on takeoff roll with the roll spoilers up essentially the whole way :eek:

LiveLeak.com - Plane Taking Off In A Typhoon: "Frightening Stuff" (http://www.liveleak.com/view?i=ddb_1242086843)

I know it's been debated here plenty of times on the proper techniques, and many who talked about 'presetting the wheel' were lambasted. Is this full LWD deflection of the wheel we're seeing?

CRH

[Rainboe]

...........

[Jumbo Driver]

I can see nothing wrong with that take-off ... it looks to me as if he did an excellent job ...


JD
:)

[latetonite]

Rainboe,

Just bear in mind that large control wheel movement can have an adverse effect on directional control near V1 (VMG) due to the additional drag of the extended spoilers. Extended spoilers also reduce your tail clearance on take-off. I would say: roll as much into the wind as you need, but keep in mind the secondary effects.

[Jumbo Driver]

... I would say: roll as much into the wind as you need, but keep in mind the secondary effects.

latetonite, the idea is certainly not to roll into wind as, if you have underslung engines to consider, roll is strictly limited. The into-wind aileron is to prevent the into-wind wing lifting, which would then induce a roll and/or drift away from the crosswind ...


JD
:)

[latetonite]

Jumbo driver,

Thanks for the correction on my wording. I guess we mean the same thing, but my English in only "level 4".

To eat up all the ground clearance for the underslung engines however, you really have to actually bank quite a bit. This danger is usually overestimated and probably not the biggest problem one encounters with a crosswind take-off, or landing, for that matter. On the 737, Boeing even had the engine pods redesigned to accommodate further.

I personally never heard of an "engine scrape" during take-off. Tailstrikes are another issue though, especially on landing.

It might be a bigger issue on 4-engined aircraft.

[RingwaySam]

Interesting video of an Air France 744F landing in Narita. Although not a takeoff it shows you the party opened speedbrakes with a similar technique.

YouTube - [720p] Hard Landing!! @ Narita - by Air France Cargo Boeing 747-400ERF ?F-GIUC? (http://www.youtube.com/watch?v=VXUs-712PF0)

[Blip]

RingwaySam I found that video really interesting. The reason being, I didn't know that the control wheel would have any effect on the ground spoilers on the left wing.

But it is clear to me that when they touchdown with lots of left rudder and right aileron, all the spoilers on the right wing deploy but only one inner spoiler deploys on the left wing. It's not until right at the very end of the video when the pilot centres the control wheel that the spoilers deploy on the left wing and become symmetrical with those on the right wing.

Theyr'e obviously a little more sophisticated than the B737.

They also almost drove the right wing into the ground on touchdown!

[JW411]

I think the Musketeer is trying to get into the Top Ten in the Darwin Awards for 2009. Isn't ignorance wonderful? He certainly doesn't know very much about getting airborne in a very strong crosswind.

In the BAe146 for example, if you don't have maximum into-wind aileron applied at the start of the take-off run in a 35 knot crosswind, you will have great difficulty in staying on the centreline (or even the runway).

This of course means that the into-wind roll spoilers will be deployed at the beginning, but as the speed increases, the amount of into-wind aileron needed reduces so that by the time you get to VR the amount of handwheel control required has reduced dramatically.

[JW411]

Cecil R Hooks:

Perhaps I can reassure you that there is a huge difference between roll spoilers and lift spoilers.

Roll spoilers are there to augment the ailerons and have little or no effect on lift. (In fact, some aircraft such as the MU-2 don't even have any ailerons but just have spoilers).

Lift spoilers deploy on landing when the aircraft is firmly on the ground. They get rid of lift very quickly, so making the aircraft "sit down" more quickly and make the stopping process much more efficient.

For lift spoilers to operate they either have to be armed or else physically deployed. Even then the "squat switch" (weight-shift mechanism) would have to also sense that either all mainwheels or the nosewheel and the into-wind mainwheels were firmly on the ground before they deployed.

In summary, it should not be possible for the lift spoilers to be deployed on take-off (unless Spanair do your maintenance) and, if I saw lift spoilers out on take-off, I would be very worried.

However, the roll spoilers shown out on your monsoon video are completely normal and would not worry me at all. I hope that helps.

[Mephistopheles]

I seem to remember that excessive control inputs resulting in spoiler deployment during a crooswind take-off actually have a weather cocking affect & makes lateral control of the aircraft even more difficult. On the Airbus a long as the "iron cross" is just about touching the black index box on the centre of your PFD then you will not have any unwanted spoiler deflection.

[inbalance]

Roll spoilers are there to augment the ailerons and have little or no effect on lift.

If the roll spoilers have no effect on lift, they are useless.

Inbalance

[ahramin]

How do roll spoilers that don't affect lift roll the airplane? Do some of these pfm airplanes also have ailerons that don't affect lift?

[capt_akun]

Perhaps I can reassure you that there is a huge difference between roll spoilers and lift spoilers.

Some aircrafts have these on the same spoiler system. The ground spoilers (roll spoilers) are activated when sensor senses weight on wheels.

[Checkboard]

Dear Pros,

Does this make you as nervous to watch as me? I would not want to be a passenger on takeoff roll with the roll spoilers up essentially the whole way

Assuming this means you are not a "Pro". No, I am not nervous watching it - in fact it seems an excellent example of a good crosswind take-off. There is absolutely no problem with the roll spoilers up during the take-off roll - and if you really did watch the video the aircraft gets airborne with good control, no wind induced roll at all and climbs away. The conditions are turbulent, as can be seen by the minor camera shake, and this turbulence results in some murmurs from the more inexperienced in the cabin (perhaps you would include yourself amongst these?).

If you wouldn't want to be a passenger for a take-off such as this, then you wouldn't want to fly with me, as this is exactly what you would see in these conditions - and I am not inexperienced.

[CecilRooseveltHooks]

Assuming this means you are not a "Pro". No, I am not nervous watching it - in fact it seems an excellent example of a good crosswind take-off. There is absolutely no problem with the roll spoilers up during the take-off roll - and if you really did watch the video the aircraft gets airborne with good control, no wind induced roll at all and climbs away. The conditions are turbulent, as can be seen by the minor camera shake, and this turbulence results in some murmurs from the more inexperienced in the cabin (perhaps you would include yourself amongst these?).

If you wouldn't want to be a passenger for a take-off such as this, then you wouldn't want to fly with me, as this is exactly what you would see in these conditions - and I am not inexperienced.

I am professional SLF with on average 75 sectors each of the last 5 years. Granted, I have not flown in Asian typhoons yet have experienced plenty of crosswind takeoffs. What I have yet to see is enough wheel deflection to see roll spoilers so extended (and you don't need to patronize and tell me I might have been sitting on the downwind wing). Could the factor be that 95% of my sectors are shorthaul (737,320 etc) and without the larger wing area of a widebody to be lifted by a crosswind less control compensation?

Glad to know I can be confident with your crosswind takeoffs, but how are the landings :8

[Exaviator]

Lift spoilers deploy on landing when the aircraft is firmly on the ground. They get rid of lift very quickly, so making the aircraft "sit down" more quickly and make the stopping process much more efficient.

Then they are called Ground Spoilers................................:rolleyes:

[Old Smokey]

Been there, done it (recently), and will do it again.:ok:

Would anyone suggest that a pilot should not use all of the normal flight controls available to keep the aircraft in a stabilised situation during Takeoff?

I'll fly with that guy (or girl) any time, a well managed Takeoff in difficult conditions ... :ok:

And yes, Roll Spoilers operate assymetrically, and only deflect a FRACTION of the full symmetrical deployment available for Ground Spoilers.

Regards,

Old Smokey

[werbil]

The controls are put there to use to their full extent when appropriate.

Try watching an experienced float plane pilot working the elevators in rough water - stop to stop to maintain the optimum planing angle through the water. Crosswind takeoffs on floats require use of full aileron to prevent the into wind wing from lifting - especially in rough water. Allow the into wind to lift too far, the aircraft to drift downwind and encounter the wrong cross swell and you risk a dynamic rollover similar to a helicopter.

Whilst I don't fly the big stuff, the principles are the same. And before anyone suggests otherwise the 208 I fly does have roll spoilers in addition to ailerons.

[Checkboard]

CecilRooseveltHooks, even as a full time pilot for 20 years in Australia, the Tropics and Europe I have only seen limiting crosswind conditions on perhaps 10 occasions, so I am not surprised you find this new to your experience. :)