Just reply the title.

Just like flaps except that they deflect Upwards and are usually smaller and on top of the wing. They increase drag and decrease lift.

Spoilers are usually deflections up from the wing in the vicinity of the center of lift, sort of at the balance point, generally (as in glider use). In that placement, they "spoil" the lift at their position, and so increase the sink rate. Spoilers have been used on glider designs for decades to aid in spot landing, however some modern military planes have also used spoilers in their complex, computer assisted control design.

On a commercial jet the spoilers deploy automatically on touch down to prevent bounce and to make sure the airplane stays on the ground.

Grandmothers

Or giving away important parts of the plot.


Spoilers break up the air moving over the wing so that portion of the wing loses significant lift. Generally they aren't necessary unless the plane is difficult to get down such as an efficient sailplane that has a very long glide slope.

As cafeen man said, spoilers break up the smooth airflow over a wing, therefor decreasing lift on that wing and causing it to drop. By dropping the inside wing, and not trying to raise the outside wing(as in inside and outside of the turn), you also avoid adverse yaw caused by the increase in lift of the outer wing.

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Three types of spoilers. They do the same thing, but are used for different reasons. In fact, many times one board of a spoiler can be used for all 3 of the functions, but that is not always the case.

Ground spoilers: Deploy after touchdown to kill all lift on an airplane after it has landed. Usually on larger airliner types or smaller jets and some turboprops.

Roll spoilers: They aid in rolling the airplane. If turn the yoke/stick to the right, the right roll spoiler will come up. That decreases lift on that wing and causes the a/c to bank to the right. Roll spoilers limit the amount of adverse yaw that is associated with just using ailerons.

Flight spoilers: They are used to help decend the a/c without picking up speed. They aren't speedbrakes, exactly, but more like lift-killers. They can make an airplane come down like a piano.


Like I said, quite a few airplanes will have all three types of functions on the same spoiler panel, or just one or two panels will be used for roll and flight spoilers but the other 5-6 will come up for ground spoilers during landing.

thanks, but I think you hit it better than I could.

In the photo you will see the spoilers on my RES sailplanes (rudder/elevator/spoilers) which provide glide path control on landing. They are also useful when we get stuck in a big powerful booming thermal that doesn't want to let us out. Pop the spoilers and decrease the lift on the wing.

Bus Driver, I agree, and whilst spoilers aren't speed brakes, they can perform that function on jet transports.

When deployed, they spoil lift, and if you want to maintain altitude, or even lose it more slowly, you have to pull the nose up, therefore more drag because of the higher angle of attack of the wing. It's sort of like putting your hand out the window of the car. With it lying flat, not much drag, but raise the front a little, and the airflow tries to pull it off your arm.

What you're doing by raising the front of your hand is creating more lift across your hand, but also creating more drag.

Bill S, spoilers deploying on touchdown are actually tranferring the weight onto the wheels from the wing so that brakes are effective. If an aircraft bounces, the spoilers don't automatically deploy until it's back on the ground, and looks like staying there. That's controlled by a 'squat switch' on the right hand landing leg (with Boeings), and unless it's compressed to a predetermined point, the spoilers don't come up.

On all transports that I know of, roll and flight spoilers are one and the same, and only the degree and method of deployment are different. Flight spoilers are used to increase descent rate or reduce speed, are manually deployed, and can operate to the maximum degree of extension. When used as roll spoilers, they are moved by the aileron control, and move through very little degree of extension.

Ground spoilers are only deployed on the ground, along with the flight spoilers, so if you look out onto the wing soon after landing, you'll see all flight and ground spoilers extended up into the airlfow. They're automatically extended when the squat switch tells the aircraft it's on the ground.

Adding a little to what Caffeen Man said, I think the B52 had only spoiler control for turning, rather than ailerons, and as a consequence, restrictions on bank angle, because if the aircraft went beyond a certain angle, the drag just pulled it into a turn from which it wasn't recoverable at lower altitudes. A B52 was lost at Fairchild AFB about 10 years ago as a result of too much bank angle down low.

John Wayne Movie?

Bus driver--But how did the piano get up there in the first place? Dang good eplanation BTW.

I love watching the spoilers come up on a commercial jet when it lands-- they look like a tin roof in a wind storm, really freaks out the nervous nellies who haven't noticed it before, they think the wing is coming apart.

I know this is getting away from the subject matter, but for those interested, the following link will take you to some info on the B52, callsign Czar 52, crash back in 1994 at Fairchild AFB.

The following is a cut and paste from the site. The article deals principally with mental phenomena associated with flying, and is not an actual accident report.

If I can find another article on how it was permitted to get that far, I'll post. It's an interesting exercise in analyzing leadership, or lack of.


http://www.visionandpsychosis.net/B52%20Crash.htm


"................that the B52 does not have wing control surfaces, ailerons, needed to correct the flight path Holland had put the plane into. There was absolutely no way that plane could achieve the stunt he attempted.

Holland is cited has having more hours in a B52 than any other pilot.

In a normal mental state he had to know that the stunt was impossible."

Spoilers are wifes or girl friends who buy you a new plane for your birthday!

Spoilers are also wives or girlfriends who make you go to their 5th cousin's wedding or bring out the "honey do" list on a perfect flying day.

Lt Col. Holland had been getting away with a series of stunts for some time when it finally caught up with him. apparently he felt he was invinceable.a number of sqdn pilots refused to fly with him. also killed was Col Wolf who was on his "fini flight "prior to retirement.