Landing Gear Options

[sprint3]

Dont know if this has ever asked. After takeoff do the brakes automaticly come on during retraction .

[The Airbuser]

Dont know if this has ever asked. After takeoff do the brakes automaticly come on during retraction .

On the MD-80's at least, I know it does. When you pull the lever up, brakes come on, stop the wheels and lock them when they are fully retracted.

Don't know how's it on other planes.

[AName]

Take a look here.

[charliepapa]

Yes, they do. The reason is basically that a moving spinning object encounters an undesirable gyroscopic effect. Basically it adds extra forces on the strut and could weaken the structure around it, or make the aircraft yaw strangely.

[Intergalactic]

I think the "RTO" aka Rejected Takeoff switch on the auto brake switch has something to do with it too. Correct me if I'm wrong, but from what I heard, using RTO doesn't mean if you abort takeoff, but it works when you lift your aircraft off the ground. They stop the wheels from spinning in midair.

I guess having at least 6-10 wheels spinning at 140 knots inside an aircraft is a bit catastrophic huh?

[rjb4000]

I think the "RTO" aka Rejected Takeoff switch on the auto brake switch has something to do with it too. Correct me if I'm wrong, but from what I heard, using RTO doesn't mean if you abort takeoff, but it works when you lift your aircraft off the ground. They stop the wheels from spinning in midair.

Negative, RTO stands for Rejected TakeOff where in the event the power levers are retarded during the takeoff roll, the auto-brakes are engaged.

[AirRabbit]

Thanks AName. Same story - part deux.

[glnflwrs]

If I'm not mistaken, RTO is a position of the Spoiler Select Switch. It extends the spoilers if takeoff is aborted causing the weight of the aircraft to be fully placed on the wheels. (At least in a C-141 anyway.)

[The Airbuser]

Negative, RTO stands for Rejected TakeOff where in the event the power levers are retarded during the takeoff roll, the auto-brakes are engaged.

If I'm not mistaken, RTO is a position of the Spoiler Select Switch. It extends the spoilers if takeoff is aborted causing the weight of the aircraft to be fully placed on the wheels. (At least in a C-141 anyway.)

The spoilers should be on the AUTO position I think, or to be extended manually. RTO on the Auto-Brakes, it's just as RJB said, it engages the brakes, wheel brakes that is.

[Ranger]

The spoilers should be on the AUTO position I think, or to be extended manually. RTO on the Auto-Brakes, it's just as RJB said, it engages the brakes, wheel brakes that is.

No. Let's try to get this all cleared up so there isn't so much guessing going on.

First, the spoilers and the autobrakes are two totally seperate systems.

Spoilers- If there is an armed/takeoff position they will normally be in that position for takeoff. If, during the takeoff roll, the thrust levers are reduced to a predetermind position on the quadrant, the spoilers will deploy. If the spoilers are armed for takeoff they can still be deployed manually. In most airplanes that means pushing the spoiler handle down (out of the armed position), pulling it back and then locking it in position by pulling the handle up (spoilers deployed). It may work a little differently on different airplanes, but you get the idea.

Autobrakes- Some have a takeoff postion, some don't. If there is a takeoff position the autobrakes will normally be in that position for takeoff. In the MD-11 that position is simply labeled TO. If, during the takeoff roll, the captain decides to execute a rejected takeoff (RTO) the brakes will automatically activate to their maximum stopping capability (max brakes).

If a RTO is done and the airplane is so equipped, both autobrakes and autospoilers come into play. But they aren't a common system nor do they activate via the same inputs. At least not on what I've flown. But as I've said many times, I'm not a Bus driver. And they might be a whole lot different on the Busses.

[Fluffdoc]

No. Let's try to get this all cleared up so there isn't so much guessing going on.

First, the spoilers and the autobrakes are two totally seperate systems.

Spoilers- If there is an armed/takeoff position they will normally be in that position for takeoff. If, during the takeoff roll, the thrust levers are reduced to a predetermind position on the quadrant, the spoilers will deploy. If the spoilers are armed for takeoff they can still be deployed manually. In most airplanes that means pushing the spoiler handle down (out of the armed position), pulling it back and then locking it in position by pulling the handle up (spoilers deployed). It may work a little differently on different airplanes, but you get the idea.

Autobrakes- Some have a takeoff postion, some don't. If there is a takeoff position the autobrakes will normally be in that position for takeoff. In the MD-11 that position is simply labeled TO. If, during the takeoff roll, the captain decides to execute a rejected takeoff (RTO) the brakes will automatically activate to their maximum stopping capability (max brakes).

If a RTO is done and the airplane is so equipped, both autobrakes and autospoilers come into play. But they aren't a common system nor do they activate via the same inputs. At least not on what I've flown. But as I've said many times, I'm not a Bus driver. And they might be a whole lot different on the Busses.

Shall we bring up the antiskid system and really confuse the topic?

[Tpattyii]

Shall we bring up the antiskid system and really confuse the topic?

Good idea

[Ranger]

Shall we bring up the antiskid system and really confuse the topic?

Oh, please. Why don't I just shoot myself instead?

Remember, everybody likes a little, but nobody likes a smart.

[AirRabbit]

Remember, everybody likes a little, but nobody likes a smart.

So ... if I always thought I was smart only to a little degree, I'd really only be a little smart?

[nameless]

Shall we bring up the antiskid system and really confuse the topic?

please do, I get the idea of the anti skid system from the name but how do they work?

Thx,
nameless

[Tpattyii]

please do, I get the idea of the anti skid system from the name but how do they work?

Thx,
nameless

To keep it easy...it works more or less like the anti skid on most every car made today.

Tp2

[nameless]

To keep it easy...it works more or less like the anti skid on most every car made today.

Tp2

so basically they pump the brakes really fast?

[Tpattyii]

so basically they pump the brakes really fast?

There are sensors in the wheel of each main. As they sense that the wheel is slipping, brake psi is reduced in order to keep the wheel from skidding. Once the wheel is kept from skidding, brake psi is added again in order to produce max braking power. The proper use of such a system if for one pilot to apply max force to the brake pedals and not let up until the aircraft comes to a stop. This would be in a case where the aircraft is needed to come to a stop in a hurry. Typical operation of the brakes is actually to use them as little as possible in order to keep the brakes from heating up, wearing out, and preventing a lashing from the chief pilot that is mad at you due to the fact that you cost the company thousands of dollars almost every time you land. It is also smart to test the anti skid system before each take off and landing to make sure that you have use of the system. If you dodon'tave use of the anti skid system before take off...you typically cant go. If you ddon'thave use of the anti skid system before you land, you will have to increase your planned landing distance and keep off the brakes until you reach a speed slow enough not to blow up the tires. (106 in the Falcon 20). Its a great system and Id hate to fly a jet without it.

Tp2

[Ranger]

so basically they pump the brakes really fast?

NO! Exactly the opposite. Antiskid RELEASES the brakes really fast. Antiskid 101-

Antiskid systems (it doesn't matter whether the system is on your car or an airplane) measure differential rotation. When the system senses a tire or wheel that is in a skidding state it release the appropriate wheel or brake(s) to equalize the rate of deceleration on both sides.

To properly use an antiskid equipped cars or airplanes the operator (driver/pilot) applies constant and very firm pressure on the brake pedals. If the system is working you'll feel a chattering sensation in your feets and toes. That chattering is the system cycling on and off. This is a pretty basic explanation of antiskid. In reality it's quite a bit more complicated. But the systems are very well designed and are almost no problem.