little piece of steel abvout 4 feet by 2 feet
Ummm....Actually, the spoilers, which are what you saw, are aluminum....small detail, really, and don't confuse the size of the item with the size of it's effect on the airflow over the wing. I don't know whether you noticed or not, but all the spoilers do is ruin the lifting effect of the wing ( they "spoil" the wing's lift) causing a much more rapid descent, the actual slowing is done by the flaps/slats and reduction of power from the engines. Modern Passenger jets don't really have "speed brakes" as a rule, altho most Military fast movers have them, in one form or another. Remember, once those big tubes stop pushing the jet forward, they can be a huge drag source! Also, and I don't know if this is still proceedure or not, I've seen 4 engine passenger jets use the reversers on the inner two engines, #'s 2&3 in the normal numbering scheme, to rapidly slow the aircraft or prevent an overspeed condition during rapid descents.
once the wheels touch ground then the reversal engines start up
Again, not to quibble over small details, but the "reversal" you notice is just the engines redirecting their thrust forward rather than aft, thereby slowing the craft with the same delta V ( change in velocity) they provide at that power setting during acceleration, like during takeoff. The spoilers are still extended, now fully, making sure the plane stays hard down on the runway (no bounces!) so the wheel brakes can do
their job too. Once the plane slows past a certain velocity, the spoilers are no longer needed, as the wings no longer provide any lift to speak of, so they are retacted, the reversers are disengaged, and the flaps raised for taxiing. From then on, the wheel brakes are adequate for speed control of the plane.
Please note also that most passenger jets utilize the spoilers on the outer end of the "down" wing during rapid roll events, such as making tight turns at low speeds, or during turbulence, to compensate for the sudden rising of a wing, when the ailerons just don't have quite enough authority to give the desired roll rate. Again, spoil the lift on a wing slightly and it drops like a stone, and bingo, rapid roll. Their use is normally controlled by the ADC (Air Data Computer) which schedules them according to altitude, desired roll rate, IAS, etc etc.
Most planes these days are fly-by-wire, which means the pilot tells the computer systems what he wants the plane to do, using the control inputs, and the computers all get together, talk about it for maybe a millisecond or so, they they move the control surfaces as needed to accomplish the desired maneuver.
I don't mean to sound like a know-it-all, and I realize a lot of confusion comes in from different languages, rough translation, lack of terminology knowledge and so on, but I grew up in the airline industry (daddy was a pilot for both the Navy, and then United for a LONG time!), I had MY pilots liscence for a short time (long story
), and I worked on Marine F-4's, so I'm pretty familiar with terminology and proceedures, and I'm just trying to clear the fog a little bit
Because while the passangers are looking at something like that, they don't see the dragon pushing against the nose of the plane to slow it down.
I always wondered why the windows are designed to prevent forward or aft vision!!
