Reply With QuoteJust call Mythbusters and let them test it.
Hey Sleek, reread the question. It never mentions wheel speed it says PLANE speed and then moves the treadmill in the opposite direction accordingly, which would mean that the plane stays stationary, which means no lift, which means no takeoff.
A plane is standing on a runway that can move (like a giant conveyor
belt). This conveyor has a control system that tracks the PLANE'S
speed and tunes the speed of the conveyor to be exactly the same (but
in the opposite direction) instantly.
Will the plane be able to take off?
Last time I checked, my airplane didn't care how fast it was traveling over the ground, it's all about the airspeed... and again, the question never states the airplane remains stationary...
If anyone wants to try this out... you can simulate this with a little rubber band powered airplane and a treadmill... Turn the treadmill up, wind the rubber band, set the airplane down on the treadmill and it will take off... :idea:
Just call Mythbusters and let them test it.
Last time I checked, my airplane didn't care how fast it was traveling over the ground, it's all about the airspeed... and again, the question never states the airplane remains stationary...
OK, so if the treadmill is going exactly the same speed as the plane in the opposite direction, thereby cancelling out any air, or ground speed, it's not going to fly. Think of it as trying to walk up the down escalator at exactly the same speed as the steps, kind of like a Slinky. You'll be in the same place all day.
So what is the answer?
I have a feelin' this is gonnabe a long day...
So if some of you think that it will not fly.
Then reverse the treadmill. Will the plane now take off twice, three, four, etc. times faster? NO. The wheels are free from power.
If the plane needs hypothetically 80 mph to take off, then when the PLANE gets to 80 mph the plane takes off, and the wheels are going 160 mph.
If the brakes on the plane were stuck, and the plane had enough engine power, wouldn't it still be able to "skid" down the runway and take off (yes, that would take a whole lot of power).
What about the military jets taking off from aircraft cariers, when taking off into the wind, the wheels are not traveling any faster than when they would take off with the wind, it is just that into the wind gets them the lift (air over wing) quicker than with the wind.
I am just glad when I fly to Chicago next month, the pilots will not be concerned with the "wheel" speed, rather its air speed. Kinda like a GPS thing.
If your are thinking along the lines of surfing or skiing "up river". It is the water flow that is creating lift, not the speed of my body. Flying is just the opposite.
Blah, blah, blah, blah................................
OK, so if the treadmill is going exactly the same speed as the plane in the opposite direction, thereby cancelling out any air, or ground speed, it's not going to fly. Think of it as trying to walk up the down escalator at exactly the same speed as the steps, kind of like a Slinky. You'll be in the same place all day.
not the same...again the wheels are not providing the forward movement, if the wheels where providing the forward movement then yes it would be the same. again ground speed would be great..but like sleek said the plane doesn't care what the wheels are turning or what ground speed is....of course this all implies that the wheels can handle the increase in speed on them and the plane can over come the rolling resistance which i am assuming isn't that much...if the tread mill match the planes airspeed then the wheel speed will just keep increasing but the plane will continue to move forward.
if you want to try this out...take a model rocket mount it to a skate, then put it on a trade mill...gurantee the skate will move against the trade mill........or take a model airplane, take the wings off fire up the motor and put it on a tread mill i bet it will move forward....
Last time I checked, my airplane didn't care how fast it was traveling over the ground, it's all about the airspeed... and again, the question never states the airplane remains stationary...
If anyone wants to try this out... you can simulate this with a little rubber band powered airplane and a treadmill... Turn the treadmill up, wind the rubber band, set the airplane down on the treadmill and it will take off... :idea:
Wow, this is great. Me and Jordy agree on something
.
Sleek, it says the plane is "standing" on the moving runway. To get airspeed you first need groundspeed which the treadmill is preventing cuz it "instantly" compensates for ground motion.
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Its like a car on a Dino.........haulin ass but going nowhere
OK, so you super techy types are way overthinking this whole deal. I even did a Google search and found where people were figuring out friction from the bearings and rolling resistance from the tires. With that much free time they should be on ***boat figuring out the amount of lift needed to unsink Later's boat.
If the treadmill is matching the plane's speed in the opposite direction as the question states, the plane will be stationary. Explain how a stationary plane can gain airspeed, without some ridiculous amount of headwind.
This is a good one. the problem is that it states that the belt can match the planes ground speed which would be very hard to do. If it can then the belt would cause to much friction and the plane could not lift off. Plane needs to move through the air to create lift. Unless it has upward thrust.
Now if the belt was spinning so fast that it created enough head wind then maybe.
If the plane had engines that pushed air over the wings that would help
In Beaverretriever's great illistration there is a problem, the problem is that the forward thrust comes from air movement not a direct connection with the ground. If the belt can move fast enough then it does not matter how fast the engines move the air.
If you had the wheels of a plane chucked on the ground, not allowing movement then the forward thrust would have a very difficult time making the plane fly. I have had a small plane at full throttle with wheel chucks and it didn't take off!
So I would say No!
but I thought yes at first.
MP
"If the treadmill is matching the plane's speed in the opposite direction as the question states, the plane will be stationary. Explain how a stationary plane can gain airspeed, without some ridiculous amount of headwind.[/QUOTE]"
Because the wheels are simply going twice as fast as the plane itself is.
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