81
votes
Accepted
How do seaplanes do run-up checks without brakes?
I'll limit my answer to single-engine seaplanes as I've never flown a multi-engine seaplane.
Typically there is no need to stay stationary in the water when doing a run-up. Just do it while taxiing ...
- 39.2k
54
votes
Accepted
Is this aerodynamic braking procedure normal in a 747?
This is not a recommended procedure for landing the 747 (or any other jet airliner I know of). The FCTM (Flight Crew Training Manual) says this:
After main gear touchdown, initiate the landing roll ...
- 58.3k
51
votes
Do airplanes really expose their internal wires and electronics like this on the wings when braking?
You will have both hydraulic system plumbing lines, the metal pipes, and wiring harnesses running along the rear spar, serving hydraulic actuators and electrical components like sensors and servos, ...
- 136k
41
votes
Accepted
Why does the Eurofighter Typhoon pitch up on brake release?
When the brakes are on, they apply a backwards force that counters the engine thrust. This force is applied at ground level, and the engine thrust is higher. These two forces result in a moment that ...
- 3,433
31
votes
Accepted
What is the "Brake to Exit" feature on the Boeing 777X?
It is a system that Airbus already uses in the A380
and some A350's. They call it BTV (Brake to Vacate).
It allows the pilot to select a certain runway exit in advance (e.g. while approaching).
...
- 3,186
31
votes
Accepted
What causes a Cessna 172 and its gear to shake violently after landing and braking?
I'm pretty sure you have encountered "nose wheel shimmy".
For reference, see this video on Youtube: c172 M Nose wheel shimmy [sic].
The shimmy can occur for a variety of reason, most likely ...
- 30.5k
30
votes
Accepted
Why do aircraft have two brake pedals instead of one?
In an aircraft the brake pedals control the respective side brakes. This allows for the pilot to turn the aircraft not only with the pivoting nose wheel (if it has one) but also with the brakes. This ...
- 102k
30
votes
Accepted
Why are thrust reversers not used to slow down to taxi speeds?
A minimum max reverse power speed is often an airplane operating limitation. It's mostly related to FOD (mostly sand grains and small gravel) and on some designs there may be compressor stall issues ...
- 136k
29
votes
Accepted
Why aren't there brake lights on aircraft?
They simply aren't necessary.
Brake lights are on road vehicles because often they travel at relatively high speeds, and follow relatively close to one another. If a driver suddenly slows, the brake ...
- 2,438
28
votes
Is Aeroflot flying airliners without brakes?
The Aeroflot warning, on which the article is based, states:
The exact translation of the message's title is:
"Safety culture (braking with a deactivated brake)". With this wording, "...
- 30.1k
28
votes
Accepted
For large commercial jets is it possible to land and slow sufficiently to leave the runway without using reverse thrust or brakes
it's possible for jetliners under typical loading scenarios... to come to a slow enough speed to exit the runway just by using spoilers, full flaps and normal friction (air and tyres) i.e. no brakes ...
- 15.8k
26
votes
Would increasing the number of wheels of a Jumbo reduce the braking distance?
Typically, a little gain is obtained.
Larger airplanes use anti-skid technology. Anti-skid works by modulating brake pressure to ensure the tires never skid. It's important to understand the relation ...
- 788
24
votes
How do seaplanes do run-up checks without brakes?
Aircraft on ski's have the same problem, and the answer is relatively simple... They do an abbreviated run-up on the go.
Even if the aircraft has a constant speed propeller, many can't feather the ...
- 36.2k
24
votes
Accepted
Why does an aircraft not spin out of control right after touch-down?
how does it not immediately start spinning?
Physics, and engineering. But I guess that you would like a bit more detail, so let's try dive in.
wheel brakes
They tend to have a stabilizing effect ...
- 32.7k
23
votes
What causes a Cessna 172 and its gear to shake violently after landing and braking?
This shaking is the infamous Cessna nose-wheel shimmy.
It is a result of the bungee connection between the nose wheel and the rudder pedals, which is required due to the way you work the rudder of a ...
- 27.9k
23
votes
Is Aeroflot flying airliners without brakes?
It is most certainly not legal* or safe for an aircraft to operate with all its brakes disabled. News reports indicate that the aircraft are 5 Boeing 777 and 4 Airbus of various types. They are less ...
- 18.2k
21
votes
Accepted
How much momentum is lost through the wheels when landing?
The vast majority of the stopping power on a landing is the wheel brakes. Reverse thrust is a much smaller component, and as it happens is generally not taken credit for in published landing distance ...
- 136k
20
votes
Why do aircraft have two brake pedals instead of one?
The left pedal is for brake(s) on the left side of the aircraft only, and likewise the right pedal for the right side.
We use two pedals because it is common where differential braking are applied, ...
- 39.8k
20
votes
Accepted
What is the temperature of the brakes after a typical landing?
Judging by this IATA document, and looking at figure 4 in section 4.2.1, the brake temperature easily exceeds 700°C during landing. They also show some brake temperature history timeline for an ...
- 324
19
votes
What is the temperature of the brakes after a typical landing?
Managing Uneven Brake Temperatures on Twin-Aisle Airplanes During Short Flights was published by Boeing in 2001. The article details the threshold temperatures for the brake overheat warning of a few ...
- 10.8k
18
votes
Accepted
Would increasing the number of wheels of a Jumbo reduce the braking distance?
Increasing the number of wheels with brakes will decrease the braking distance as there's more sources of friction to convert the kinetic energy. Doubling the number of wheels per brake (I think what ...
- 54.4k
17
votes
Why are brake temperature limitations lower when the brake fans are running?
The fans cool not only the brakes, but also the temperature sensors, at different rates. The temperature difference is a measure to correct this anomaly. From the document Proper Operation of Carbon ...
- 101k
17
votes
How do seaplanes do run-up checks without brakes?
Float planes have variable pitch propellers, meaning that the propeller blade can be angled so that it does not provide any forward movement at all, or even turned backwards so it pushes the airplane ...
- 31k
17
votes
What ground speed reference is used for anti skid control?
On the Airbus A320, the ADIRU (Air Data Inertial Reference Unit) data is used for the reference speed of the anti-skid system:
The system compares the speed of each main gear wheel (given by a
...
- 58.3k
17
votes
For large commercial jets is it possible to land and slow sufficiently to leave the runway without using reverse thrust or brakes
No, in the general case it isn't even close to possible.
You land a 60-ton aircraft at 120 mph, and it has to slow to (let's say) 30 mph in the space of (being generous) 2 miles, with no braking? No ...
- 53.6k
16
votes
Could an airliner abort a landing after using the brakes system while landing?
Immediately after touchdown, the autobrakes will start to function, and may start applying the brakes depending on the aircraft's deceleration and the commanded deceleration. If the pilot hasn't yet ...
- 53.6k
15
votes
Accepted
What is the preferred way to slow down an airliner on a long runway?
There are several ways to slow down an airliner:
aerodynamic drag
friction in the wheel bearings
reverse thrust
wheel brakes
and a few even used a brake chute, but that went out of fashion a long ...
- 237k
15
votes
Would a stationary WWII fighter fall on its nose with full throttle and brakes on?
This was also an issue when doing maintenance. For engine ground running at full power, the tail of the aircraft was weighted down to stop the aircraft tipping over the front wheels.
You can see the "...
- 3,030
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