I was watching mythbusters tv show tonight and saw a plane sitting there with the engines fully powered, and it didnt go anywhere. Why is that im just curious, they have the power to make it take off but not to make it move when its locked or whatever is holding it back from moving.
2007-11-15 16:56:51 · 15 answers · asked by fyreman81 2 in Cars & Transportation ➔ Aircraft
i understand planes have breaks, i just wonder if they are actually that strong to hold up to full throttle and not move any where.
2007-11-15 17:53:45 · update #1
A 747 has 4 main gear's with 16 tires in total (without the nose gear) Each tire carries a package of brake disks (a stackup of stator and rotor disks, rotor disks are like the brake of a car, if you put force on it, you change kinetic energy into thermal energy. Modern jets carry Carbon brake disks in order to stand the high temperatures that occur during braking after landing. Brakes are powered with a hydraulic pressure of 3000 Pounds per Square Inch (PSI)
Generally these brake packages deliver 75-80% of the total break force during the landing phase (thrust reverse and speed brakes only 20-25%).
In order to reduce the Take Of Distance Required a pilot can fasten all the brakes, and power up to Full engine power. It takes the engines some time to reach max RPM so you don't want the aircraft to move before max power is reached. Doing this reduces the runway length required to reach take-off speed. The only reason to use this method is a take off from a short runway.
2007-11-15 18:41:50 · answer #1 · answered by Anonymous · 1⤊ 1⤋
you've 3 questions. Q1: A 747 can no longer carry any altitude with 3 engines out. The plan will decelerate and stall, and fall out of the sky if the altitude is held. Q2: A 747 can land adequately if an airport is on the point of the region that the three engines stopped generating thrust. Q3: A "crash landing" isn't a landing. that's a crash. i have been a prevalent aviation deepest pilot for the reason that 1980. I have a unmarried engine land score, and a unmarried engine sea score. I took some multi-engine preparation, in basic terms never were given the score. I flew once throughout the Atlantic Ocean as a passenger of a 747. The pilot allowed me to visit the cockpit in the course of the flight and replied my questions. One, changed into no matter if the airplane might want to carry altitude with 2 engines out of a similar wing. The very thick flight guide got here out and that i changed into shown some charts. it type of feels that the 747 might want to absolutely climb at one hundred ft in accordance to minute in that condition. yet there is not any way it may fly some distance on in difficulty-free words one engine. Altitude might want to be traded
2016-10-24 08:02:29 · answer #2 · answered by buncie 4 · 0⤊ 0⤋
When doing ground testing of the engines or doing a "trim run" they are chocked and the parking brake is set. The throttles are advanced to the needed setting making sure the power is balanced between sides. You will not see a four engine jet running all four engines at full power on the ground. It is too much of a safety concern for potential damage to the aircraft and the crew running the maintenance check. When this type of run is done on the ground, there is always a mechanic in the FO seat (right side) to watch for any unexpected forward movement and apply the brakes if the parking brake fails.
2007-11-16 02:49:23 · answer #3 · answered by Otto 7 · 0⤊ 0⤋
I just watched this Mythbusters episode last night. The Kalitta Air Cargo's 747 was actually tied down on an engine run-up pad. This is frequently done after engine maintenance to allow the engines to be run at full power for ground testing.
An odd bit of trivia... The big 747 used in this episode is owned by Conrad Kalitta... Also known as Connie "The Bounty Hunter" Kalitta who was a world champion drag racer back in the 1960's and 1970's. He started his airline career using a twin-engined Cessna 310 that he won in a poker game!
2007-11-16 02:35:22 · answer #4 · answered by JetDoc 7 · 1⤊ 1⤋
Yes the breaks can hold it stationary while the engines fully powered up. With 18 wheels on a 747 you can understand why this is possible. They can set the breaks and spool the engines up to full power before take off. Although unusual this kind of take off might be used when weight constants or runway length make it necessary.
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2007-11-15 18:11:48 · answer #5 · answered by ericbryce2 7 · 2⤊ 1⤋
From what I saw, only two of the engines were at full throttle, which would explain in part why the plane didn't go anywhere.
2007-11-16 01:58:33 · answer #6 · answered by Anonymous · 0⤊ 0⤋
When I was in the Air Force, we'd do engine runs on the ramp (F-4's). The brakes were set, and the Main Landing Gear tires were chocked. This was only allowed up to 50% power. Over that, there was a risk of the plane "jumping chocks" (rolling over the chocks restraining them). If we had to run over 50% power, we had to tow it to a pad that had fittings in the ground that we could tie it down with (using cables with clevis'.
2007-11-16 02:29:09 · answer #7 · answered by strech 7 · 1⤊ 0⤋
In a manner of speaking, the engines were not fully-powered, as only two of the engines were at full throttle.
Carefully watch that episode again, and you'll notice that only two of the throttles are "firewalled."
2007-11-16 01:56:06 · answer #8 · answered by Paul A 4 · 0⤊ 0⤋
With the wheels chocked, and only two engines at full power, it's no small surprise that the plane didn't go anywhere.
2007-11-16 02:04:24 · answer #9 · answered by Kiki 2 · 0⤊ 0⤋
If the plane was at full power, then why were two of the throttle levers at idle?
2007-11-16 02:01:06 · answer #10 · answered by Deah K 2 · 0⤊ 0⤋