Hot answers tagged

81

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 to your takeoff path, or you can do it on your takeoff path. If the takeoff path isn't long enough to do the run-up and then continue along the path for the ...


41

Yes, they do. They are called Anti-Skid and they go from Mark I of 1948, with simply an on-off switch triggered by wheel lock, till Mark V (or at least that's the last I've seen), with quite complex control systems and sensors behind. The full details are a bit long to include them all here (there are entire book sections about them). For a brief overview, ...


41

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 forces the nose down, compressing the nose gear slightly. When the brakes are released, the moment disappears and the nose gear extends. Another factor here is ...


39

An airplane can slow down and reduce its speed while in flight. The easiest way to do so is to reduce the amount of thrust that the engines are producing. This will produce an almost immediate reduction of the airspeed, especially if the plane is maintaining the same altitude. There are also devices called air brakes and spoilers that can be further used ...


31

All of the aircraft that I have ever seen have the rudder and braking functions combined into one set of two pedals. To operate the rudder you press on the bottom part of the pedals, so that they slide back and forth on tracks, and to operate the brakes, you press the top part of the pedals so that they rotate towards the floor. The left pedal operates the ...


30

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 allows for a very tight turning radius. (source) If each pedals controls different sets of wheels eg the left wheels and the right wheels of the main ...


29

It is not called ABS but Anti-Skid, but the principle is similar. All large aircraft have it. The purpose is however slightly different. In aircraft the nose wheel has relatively little weight on it and is usually not braked, so directional control, the main reason for ABS in cars, is possible¹ even without anti-skid. However due to the higher speeds and ...


29

A number of things happen when you rotate the canards by 90°, and in no way I see how these could be addressed by not too many modifications 1. Transient Once you land, you need a certain amount of time to rotate the canards. During this time the canards will not produce a perfectly horizontal force, but it will have also a vertical component. Whether ...


29

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 lights help provide a visual cue (which grabs the attention of other drivers, and is visible from quite a long distance) that the vehicle intends to slow or ...


29

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 due to flow disruptions. On the CRJ 700 max reverse is limited to 75kt although you can use up to 60% N1 down to zero speed. On a 900 you have to be at idle ...


28

The brakes are much more effective than anything else, at least for the jet I have experience in (EMB-145). Our landing performance data typically assumes full braking application, spoilers deployed and no reverse thrust. The airplane will most certainly stop without using reverse thrust, just not as fast. I never tried not using the brakes, and if I ...


26

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). After touchdown, the plane automatically brakes so it can vacate the runway at that given exit. Airbus says: When the pilot chooses a runway exit point, the ...


25

For several reasons. First to protect the drogue from damage by scraping on the pavement second to prevent it from becoming snagged on nearby objects third to prevent metal components on the drogue from hitting and damaging the tail of the aircraft, and fourth to make it easier to taxi back to the ramp without the need for higher power setting to overcome ...


25

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 between a tire's load, brake pressure, and actual retarding force. First, look at this image : It shows how as you increase pressure and the wheel starts ...


24

This answer to another question has a link suggesting that the spinning wheels may be sufficiently large gyroscopes to affect handling of the aircraft. That was however on a larger aircraft and higher speed (Lockheed Constellation). I don't know whether that effect would be observable on TB10.


24

(Wikimedia; arrows and CG icon are my additions) P-47 side drawing. The thrust has a bigger moment arm around the tires contact points compared to the weight. It won't nose over below a certain RPM (it will be specified in the training). Below that RPM: The weight will counter the thrust The propeller downwash will produce downward force on the horizontal ...


24

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 propeller enough to completely prevent motion. There are a few piston light aircraft that have a feathering prop, and one that I know of that can actually ...


24

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 by shifting some of the weight on the front wheel and allowing the pilots to control the aircraft with more effectiveness. spoilers These are automatically ...


22

Yes they are. In fact this is required for a static takeoff. A static take-off means setting the brakes and running up the engines to takeoff power then when ready they release the brakes and start the takeoff roll. Besides that one of the test Airliners have to withstand is a worst-case V1 abort. This means starting a takeoff and at the last second slam ...


21

There are specific protocols that procedurally are required to be followed. Insofar as brake inspection is concerned, it would have been obvious from the trucks that there was no brake fire. It's also obvious that there's not a major amount of smoke coming from the brakes. As they approached the landing gear, they would have smelled serious brake heating. ...


20

On a Cessna 172, spinning wheels do create vibrations. Once the brakes are hit the vibrations stop. It could be due to the wheel balancing.


19

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 airplane without fan cooling. (Figure 4)


19

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, in other words different amount of braking on the two sides of the aircraft. This is handy for maneuvering the aircraft around corners. For example if the plane ...


18

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 different twin-aisle plane types. Assuming that during a typical landing the brake overheat warning is not triggered and the brake system is not excessively ...


17

There are a couple of reason for the presence of thrust reversers: To reduce wear on the brakes. To provide a margin of safety (for example in wet conditions). In 1995, NASA carried out a survey on airlines Why Do Airlines Want and Use Thrust Reversers?. The results of the survey, though dated, give an indication of presence of thrust reversers. The main ...


17

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 backwards a little bit. When the engines are started, or during run-up tests, the propeller pitch is set so that it does not provide any thrust. When flying, ...


16

Both are in taxiing SOP. The reason is in case the spoilers were accidentally left extended on the flight before (or during a maintenance check before the flight by the line engineers). If that's the case, then pressing MAX while taxiing before checking the flight controls (spoilers included) will engage the full RTO brakes and surprise the crew, injure a ...


15

My initial hunch tells me that the reason for this is a bit of angular momentum. Remember back when you were a kid, first learning to ride a bike? At some point you realized that the more speed you have, the more stable you are on your bicycle. This is because of angular momentum. So imagine your up in the air, and you have to wheels rotating at 75 rpm (...


15

Perhaps instead of thinking of a single primary means of slowing a large jet, we should think about a primary means for a given set of conditions, the combinations of which are numerous. To mention a few: What is the weight of the aircraft. Passenger aircraft are typically nowhere near max landing weight when they land. Freighters are often loaded such that ...


15

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 time ago. If the runway is inclined, landing uphill also will slow down the aircraft. Friction and drag you get for free, so I would rely on those first. Since ...


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