AirPlane on a Teardmill and Mythbusters

[snoblinders]

i hope those that think it wont take off are kidding!

to make it easier for some of you tards how about if a float plane is in a river?
you dont think it can take off going up stream?? the only thrust needed to stay in one spot is just enough to overcome the friction of the floats, same as a plane on a conveyor, just enough thrust to overcome the friction in the wheel bearings and the tire friction.

 

[sortastock]

Escape! went through and reread your posts! welcome to the club! Feels good, doesn't it?

 

[EastcapeAngler]

Escape! went through and reread your posts! welcome to the club! Feels good, doesn't it?

..That's "Eastcape" to you pardner'

 

[Meatman]

awww EA, we are sooo proud of you, ya little post whore you

its still going to spontaneosly combust end of story case closed

 

[khaddon2110]

So the speed of the conveyor belts perfectly match the thrust of the engines so that the plane has NO forward movement whatsoever in relationship to the ground, right?
Conveyor belt speed/wheel speed = 300MPH
True ground speed = 0MPH
True airspeed = 0MPH
Speed of air over wings = 0MPH
The airplane has less of a chance of getting airborne than the XP has of winning the "MOST RELIABLE SLED OF THE YEAR" award.

Unbelievable! No that is not correct. Go back and look at the scenario again and you will see that the conveyor speed matches the wheel speed, not engine thrust. So The plane will move forward and eventually fly, If we could find a treadmill long enough.

It will be interesting to see how Myth dudes will attempt this. Full scale could make it interesting.

 

[EastcapeAngler]

awww EA, we are sooo proud of you, ya little post whore you

its still going to spontaneosly combust end of story case closed

..I feel all warm & fuzzy inside right now... Kind of like the feeling I got when I shot my roomate's miniature Dobie with bear spray

 

[Supplicate]

Go back and look at the scenario again and you will see that the conveyor speed matches the wheel speed, not engine thrust.

hmm... and why won't thrust = wheel speed? Once again I will say this, the wheels need something to drive them. In the case of a car it is a driveshaft going through the diff's and axles, in the case of a plane its thrust pushing on air, in the case of a skateboard its the riders foot on the ground, in the case of a snowmobile its the clutches to the driveshaft to the track.

 

[Mafesto]

This IS frustrating!

Let's say a given plane has to go 100 mph to lift off.

If the same plane is taking off into a 20 mph wind, it now has to go 80 mph (ground speed) to lift off.


If the same plane is taking off with a 20 mph tail wind, it now has to go 120 mph (ground speed) to lift off.

Does this make clear the point that ground speed & air speed in this scenario have nothing to do with one another?

 

[EastcapeAngler]

..The earth rotates, spins,travels, or however you want to word it,,,at about 1,000MPH.... So what makes ANYBODY think a treadmill is gonna hinder takeoff?

 

[Supplicate]

Does this make clear the point that ground speed & air speed in this scenario have nothing to do with one another?

They have everything to do with it. You can't get wind speed without ground speed, or does your plane suddenly jump to 100mph without rolling on the ground first? If ground speed has nothing to do with it, does your plane hover instead of taxi? In your scenarios you still needed ground speed to develop enough lift. If your engines are going at full thrust and the conveyor is at the same speed backwards as your wheels are forwards, your net speed is zero. Net speed has to be greater then zero for any possibility to take off.

Yet again, I will state this: If net speed < 0, it will move backwards, net speed = 0 (as in the original parameters of this question) nothing hapens other then burning fuel, if net speed > 0 then it will take off.

Its all in how you interpert the question.

 

[Supplicate]

..The earth rotates, spins,travels, or however you want to word it,,,at about 1,000MPH.... So what makes ANYBODY think a treadmill is gonna hinder takeoff?

hmmm... Think about that one for a second. It actually takes a plane less fuel to fly oposite the rotation because once they are in the air it could basically be said they are just holding position until where they want to land rotates into position beneath them. By the same principle it takes more fuel to go with the rotation of the earth because once they are in the air their destination is moving away from them.

edit: and before someone else points it out, this is neglecting the effect of the jet stream and prevailing winds.

 

[Scott]

LMFAO, this schit is funny.

 

[khaddon2110]

could I flip my sled upside down and use it for a conveyor belt?

 

[Redneck Farmer]

They have everything to do with it. You can't get wind speed without ground speed, or does your plane suddenly jump to 100mph without rolling on the ground first? If ground speed has nothing to do with it, does your plane hover instead of taxi? In your scenarios you still needed ground speed to develop enough lift. If your engines are going at full thrust and the conveyor is at the same speed backwards as your wheels are forwards, your net speed is zero. Net speed has to be greater then zero for any possibility to take off.

Yet again, I will state this: If net speed < 0, it will move backwards, net speed = 0 (as in the original parameters of this question) nothing hapens other then burning fuel, if net speed > 0 then it will take off.

Its all in how you interpert the question.

You need to go back to Junior High. This is 7th grade type physics at best. The wheels have nothing whatsoever to do with ground speed. They are FREEWHEELING.

If the plane has a 100mph takeoff speed, then the treadmill will be moving 100 mph in the opposite direction and the wheels will be spinning effectively 200mph when the plane lifts off. That treadmill could be spinning 1000mph in the opposite direction, and if the wheel bearings would hold together, the plane would still take off.

 

[Mafesto]

You can't get wind speed without ground speed,
In your scenarios you still needed ground speed to develop enough lift. If your engines are going at full thrust and the conveyor is at the same speed backwards as your wheels are forwards, your net speed is zero. Net speed has to be greater then zero for any possibility to take off.

Yet again, I will state this: If net speed < 0, it will move backwards, net speed = 0 (as in the original parameters of this question) nothing hapens other then burning fuel, if net speed > 0 then it will take off.

Its all in how you interpert the question.

Let me ask it to you this way.....

What makes you think a conveyor (of any size & speed) would keep the airplane from moving forward?

The belt moving under the tires have no effective resistance to the planes forward movement.

 

[EastcapeAngler]

 

[Meatman]

bwahahaha supplicate....the wheels are not under power

grab a belt sander, and oh i dont know a wheel with a bearing....say a wheel off the skid of your sled

place something through the bearing that makes a tight fit so the wheel spins freely on the axle

with the belt sander upside down with a good grip on the axle place the wheel on the sander and turn it on. see the wheel spin freely?

Do you know what is spinning that wheel? That is correct, the belt sander is causing that wheel to spin

now with the sander still on and you still holding the axle while the wheel is spinning, move the wheel in the opposite direction of the belt.

Do you know why it is moving freely against the direction of rotation of the belt sander? Because the force that is moving the wheel is coming from an outside source of power

Now let's apply this to the airplane/conveyor question. the conveyor (belt sander) the wheels of the airplane (the wheel and axle set up from our little experiement) and the engines of an airplane which propels the plane (your hand holding/moving the wheel and axle) This should spell it out for most of you. being that i incorporated shop tools and snowmobile parts

 

[Supplicate]

The belt moving under the tires have no effective resistance to the planes forward movement.

Okay, prove to me that this is the truth.

Are you looking at forward movement comparitve to the conveyor (of corse its gonna look like its moving forward when you just look at the conveyor) or are you looking at forward movement comparitive to the ground beneath the conveyor (which is static and not rolling backwards)?

 

[Supplicate]

bwahahaha supplicate....the wheels are not under power

Bullsh!t the wheels aren't under power. Its like saying a skateboard isn't under power. If the wheels weren't under power they wouldn't go anywhere. What fun would standing on a skateboard on a flat surface be?

Everything needs force (power) to move, just because the wheels aren't being driven by a drive shaft doesn't mean they aren't being pushed by power.

edit:

meatman, the thing you aren't thinking of is the weight of the airplane pushing down on the wheels. This would ramp up the rolling resistence of the wheels thereby negating your refrence with freewheeling a wheel on a sander belt. The more pressure (weight) you apply to the wheel, the more it will want to stay in place on the belt and move backwards, which means the more force (thrust) you have to apply in a forward mortion to keep it in a static position, which means even more force (thrust) you need to apply to get any motion that nets out in the forward direction.


edit 2:

you also aren't factoring into this the compound of the wheels. A hard plastic wheel will have lest drag (grip) on the belt then a soft rubber wheel. The more grip a wheel has on the belt with higher rolling resistence the more it will want to stay in place. Now, the more grip a wheel has on the belt with lesser rolling resistence, the easier it will freewheel.

If you want to do a scale experiment using your belt sander, figure out a way to replicate 3 tons of downward force on the belt.

 

[EastcapeAngler]

About 60,000 more posts & we overtake the useless max thread!!!