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Questions tagged [braking]

Questions about usage of mechanical brakes on the wheels for slowing down.

2
votes
2answers
126 views

What is the 'fuel cost' of a pneumatic braking system vs. a hydraulic one, in terms of weight?

A pneumatic braking system has indisputable advantages over a hydraulic braking system for large and heavy aircraft in terms of braking force and secondary perhaps in terms of weight (pipes and ...
11
votes
1answer
298 views

Why is braking action (with Anti-Skid) best when the wheel rotates at ~85% of the actual speed?

During my ATPL training the subject of tires and braking was discussed. I understand the principle of the anti-skid and also the differences between aircraft and similar systems in cars. Physics also ...
2
votes
2answers
462 views

What happens if an A320 goes to full throttle with the parking brake set? [duplicate]

The question is simple: what happens? Is the aircraft going to stay stationary, or will the engine power overcome the brakes? I'm assuming everything is fully functional. I know the FCOM says not ...
9
votes
2answers
533 views

Is aerodynamic braking really effective?

(YouTube) In the frame above the pilot is pulling back, as evident by the stabilator's position, and this technique is usually cited as a means of slowing down. But wouldn't the brakes have better ...
2
votes
1answer
130 views

How can I reduce the responsivness of my homebrew brake system?

I have a hydraulically actuated aircraft brake system. Each main landing gear are equipped with brake disk hydraulically operated. The actuation is realized independently for each wheels by means of ...
3
votes
2answers
246 views

Do large Airliners use full thrust when reversers are deployed?

Do large and heavy Airliners, Jumbos and Super Jumbos wide bodies included use full thrust for braking when reversers are deployed? What is the thrust setting?
3
votes
2answers
370 views

Why is V1 based only on using brakes?

V1 is the speed that an aircraft may abort a takeoff so long as the airspeed is below it, or is committed to flight if it is over that speed. V1 calculations are based only on the brakes (not sure ...
8
votes
2answers
833 views

Why are parking brakes not used for parking jetliners?

From the question 'Do I Set the Parking Brake On the Ramp?' it is concluded that you do not set the parking brake when parking the aircraft. The question concerns small aircraft which can be parked ...
3
votes
1answer
123 views

What guidance is there for pilots when reporting braking action?

I was listening to "[REAL ATC] Eastern B737 (candidate Mike Pence) OFF RUNWAY at LaGuardia!"(1) and the LGA Tower asks for and receives reports of braking action from several landing pilots. I assume ...
22
votes
6answers
4k views

Would increasing the number of wheels of a Jumbo reduce the braking distance?

If weight was not an issue, would increasing the number of main gear wheels on a jumbo such as the Airbus A380 from 20 to 40 wheels, each equipped with braking disks and braking equipment, considering ...
12
votes
3answers
2k views

Why aren't there brake lights on aircraft?

Why don't aircraft have brake lights so you can see when an aircraft in front is slowing down? I know there are air traffic controllers to control aircraft but they cannot do much about an aircraft's ...
8
votes
1answer
480 views

Does the 747-8 / A380 nose-wheel encounter more weight during braking?

Given that the nose wheels of both the Boeing 747-8 and Airbus A380, as is true for almost all aircraft, are not equipped with brakes, do they encounter more weight during braking? If so, how much ...
5
votes
1answer
205 views

On the new A320s when we do a brake check there is no need to call pressure 0 why?

Why do we have a give a pressure 0 call out when checking brakes while taxi on the old A320s but not in the newer A320s.?
1
vote
0answers
227 views

Can MIL-PRF-5606H hydraulic fluid be used in place of MIL-PRF-5606?

Can MIL-PRF-5606H hydraulic fluid be used in place of MIL-PRF-5606? My airplane is a 1966 Piper Cherokee 6.
1
vote
0answers
228 views

Why do we have to do an alternate brake check during preliminary cockpit preparation?

As part of the preliminary cockpit preparation in my company’s older A320s we have to perform an alternate brake system check but not in the newer ones as per FCOM Normal procedures as below. I found ...
5
votes
1answer
100 views

Does the weather condition of the runway affect the braking of an aircraft with regards to wheel braking and reverse thrust?

I was on a 737 that landed on a snowy runway in northern Finland the other day. We had to wait around 30 minutes to land as they were waiting for it to stop snowing and then for them to clear the ...
16
votes
5answers
8k views

Why does an aircraft not spin out of control right after touch-down?

When a plane is landing, how does it not immediately start spinning out of control? Given the massive amount of forward momentum and the fact that all the various braking forces (wheel brakes, ...
3
votes
3answers
275 views

Why do we often have more than one method of slowing down (retarding) aircraft on the ground?

Why do we often have more than (thrust reversers and brake chute) one method of slowing down (retarding) aircraft on the ground?
7
votes
3answers
508 views

How much force are large aircraft brakes able to exert?

In a comment left on my answer here Jan Hudec says: Note that usually on dry surface the brakes exert much less force than the tires could handle. This got me wondering how much force large ...
2
votes
1answer
139 views

How does the forward speed of an auto-gyro relate to the rotation speed of the rotor during auto-rotation?

In my other question I was looking for a relation between the forward speed and the thrust (lift) of an auto-gyro. I have come to the conclusion that for an auto-gyro in auto-rotation the forward ...
2
votes
4answers
543 views

Is it feasible to recuperate energy from landing aircraft by using a runway sled with regenerative braking?

Would it be feasible to land large (Boeing 747 and Airbus A380) and all other aircraft on a sled on the runway, the kinetic energy of the aircraft is then transferred to the sled, then the sled uses ...
3
votes
1answer
147 views

What is typical thrust to braking force ratio for a passenger airliner?

Is the ratio fairly constant across aircraft types, sizes and powerplants? I'd like to ignore the reverse thrust component, since that's not available at the same time as forward thrust.
53
votes
4answers
9k views

How do seaplanes do run-up checks without brakes?

Usually on run-up you want to check the response of the motor when changing for example the carb-heat (if existent). At least we did so on my intro flight (yey!). To prevent us from rolling onto the ...
11
votes
1answer
1k views

Why are brake temperature limitations lower when the brake fans are running?

In the A320 FCOM it is stated that if the brake fans are running prior to takeoff then the brake temperature must be below 150 degrees Celsius. But if the brake fans are off then our limitation is 300 ...
6
votes
2answers
233 views

Are the captain's and first officer's brake pedals always mechanically linked?

I heard that for Boeing and Airbus aircraft, the pilot's and copilot's brake pedals are mechanically linked, is that true? Why did they make that design decision? What's the advantage? Do all kinds ...
18
votes
4answers
8k views

Why do aircraft have two brake pedals instead of one?

Why do aircraft have two brake pedals instead of one? If each pedal controls different sets of wheels e.g. the left wheels and the right wheels of the main gear, is that not a safety flaw given that ...
4
votes
0answers
175 views

What is the effect of sudden extreme temperature change on brake disks of large aircraft?

What is the temperature of brake disks at maximum altitude of a jumbo like a 747 and airbus A380 for say a 10 hour flight. Does the temperature drop below zero and what is the effect on the metal ...
2
votes
0answers
85 views

Why is there only circumferential treading on the nose wheel? [duplicate]

The pilot uses the nose wheel for steering on the ground, still all the tires on the aircraft use the same treading. Why are there no treads perpendicular to the rotation direction? I know that most ...
5
votes
3answers
997 views

Do parking brakes lock the wheels and airframe together?

(YouTube) Wildcat undercarriage. For planes with non-truck undercarriages, can they be rotated around the lateral axis of the main landing gear with the brakes applied without causing translation? ...
17
votes
3answers
4k views

Would a stationary WWII fighter fall on its nose with full throttle and brakes on?

Would a stationary WWII fighter fall on its nose with full throttle and brakes on? It's a general question, but I am interested in the Republic P-47.
-6
votes
1answer
2k views

How do multiple-disc brakes work?

Multiple disc brakes uses stators & rotors to brake? How do they work? (Source)
1
vote
1answer
238 views

What brakes are used between line-up and takeoff?

I was wondering if an airliner was instructed to line-up on the runway ("line-up and wait"), will the park brake be used or will manual braking be used (pedals) during the wait until the take-off ...
3
votes
3answers
586 views

Have Eddy current brakes ever been used/tested on an aircraft?

Eddy current brakes (wiki) --- a.k.a. magnetic brakes --- get quite some attention from train engineers. They are used on Shinkansens, roller coasters, and even (as far as I know) metro trains on Lane ...
5
votes
1answer
2k views

How often are heavy aircraft brake pads changed?

How often are Boeing 747-800 and Airbus A380 aircraft brake pads changed?
9
votes
4answers
1k views

What is the preferred way to slow down an airliner on a long runway?

EDIT: Another way to phrase the question is, given an extra long runway, does it make sense to substitute mechanical braking (which is the primary way to slow down in a typical situation) partially or ...
20
votes
3answers
7k views

What is the temperature of the brakes after a typical landing?

On an airliner, what is the temperature of the brakes after a typical landing, and how long does it take to cool down? Is it hot enough that mechanics should wait before servicing an aircraft that ...
6
votes
1answer
300 views

How does EMAS reduce damage in case of an aircraft overrun?

I saw a report about Mike Pence's plane overrun today on Twitter link: Mike Pence plane overrun photo on Twitter. As can be seen there is huge cracks and breaking of the runway but the plane was ...
0
votes
1answer
249 views

Can an aircraft (civilian or military) land with its brakes already engaged? [duplicate]

Can an aircraft land with its brakes already engaged at the max landing speed of that aircraft?
11
votes
4answers
2k views

What effect would there be if the brakes were locked at touchdown?

I'm imagining if you had a panicky passenger sitting in the right seat who had both feet firmly on the brakes while landing. Unless you had a crosswind and needed rudder as you touched down it's ...
16
votes
3answers
2k views

Why is the drogue parachute jettisoned on the runway?

Why is the drogue parachute of a military plane jettisoned on the runway? Why not drag it to the parking area for safe removal, inspection, and repacking?
9
votes
2answers
1k views

How does landing performance differ on water vs. ice vs. paved/grass runways?

It's a follow up from How do aircraft brake when using skis? Can someone give me data about difference between landing distance for each environment ? Paved Grass Water Snow/Ice Any aircraft is ...
15
votes
2answers
2k views

How do aircraft brake when using skis?

Planes use skis to land on ice/snow runaway. How can the plane brake in such conditions? Friction must be limited to allow takeoff and aerodynamic braking are not the main contributors to the ...
15
votes
2answers
3k views

Why aren't the canards used as airbrakes on the Tupolev Tu-144?

The Tupolev TU-144 uses retractable canards to stabilize the aircraft while starting and landing. On this picture you can see them very well: Source: AirlineFan.com Copyright: VOLPATI It doesn't ...
14
votes
2answers
1k views

Why do modern jetliners provide Thrust Reversers at all in their design decisions?

Let's start with the following knowns (please correct me if I am wrong about any): The braking force provided by the wheel brakes is much larger than that by the thrust reversers One is not allowed ...
12
votes
1answer
497 views

What are the relative braking contributions from wheel brakes, spoilers and thrust reversers?

What is the relative contribution to braking forces in a typical large commercial aircraft from the three different devices contributing to braking after touchdown: Wheel brakes Speed brakes / ...
37
votes
3answers
6k views

Do commercial aeroplanes use ABS to brake?

I have read that the wheel brakes on an aeroplane are by for the most efficient means of stopping it. I was wondering whether in low grip situations, such as in rain or snow, an ABS (Anti-lock Braking ...
3
votes
2answers
2k views

Where is the regular wheel brake input on modern airliners?

I learned that on modern airliners, the Rudder input is given by the pedals located under the pilot's feet, and that got me thinking: how do the pilots give the command to brake the plane in order to ...
2
votes
3answers
524 views

what are the ways to avoid skidding off the runway apart from thrust reversers? [duplicate]

what are the different ways to avoid skidding off the runway apart from thrust reversers? Do crew have any option if thrust reversers are not available and the ground is too slippery which is making ...
7
votes
1answer
6k views

In an emergency, how much runway does an A320 need to stop safely?

From time to time I land at Wellington Airport in an A-320. The runway has sea at either end and is 2,081m (6,827ft) long. There's never been a problem but I find landing there a bit nerve wracking ...
7
votes
1answer
2k views

What is Brake To Vacate (BTV)?

Emirates has this feature on many of its A380s. From what I've read, the feature decreases the amount of runway an aircraft uses after landing. It also helps the aircraft achieve a certain exit way. ...