Can the airplane take off?

[smack Down]

Originally posted by: AeroEngy

Originally posted by: smack Down

Originally posted by: AeroEngy
Soemone mentioned they wanted to see a free-body diagram so i created one LINK

You keep talking about torque which would just be the force applied by the treadmill times the radius of the tire. The amount of force is dictated by the friction between the tire and the treadmill surface. This value is easly obtained by a high school level physics equation for rolling friction. Look at the daigram.

Note: All the aircraft data was from an F-16 and can be found on wikipedia. Rolling Friction Coeficient was taken from an ordinary tire form the table in wikipedia(just search for rolling friciton). In the F=m*a equation I had to convert the mass to slugs to make the dimensions consistant. I also only showed the X-componet of all the force vectors because Y-re doesn't matter in this case.

If you assume the tires can slip then the plane would take off. I'm assuming prefect tires.

You are not following what rolling friction means. The tires in the diagram do not slip. They roll over the surface of the treadmill. Any object rolling not sliding over any other object has a rolling frcition coefficient. The force I showed was the force required to roll the tires loaded with the weight of the plane along the surface of the treadmill with Zero slip between the two. If there was slip then I would have to use a sliding friciton coefficient which would be higher. Which would also mean burning rubber everywhere.

I think the reason your imaginary plane won't take off is becuase you have snakes on it.

Oh ok, I was think rolling friction was the point when a object started to slide.

here is the FBD you should have drawn
http://img145.imageshack.us/img145/811/fbdoi9.jpg

 

[MrPickins]

Originally posted by: smack Down
Sorry one point of contract means it can't spin with out moving the object attached to the tire.

You are too much. I have to thank you for giving me such a good laugh all evening. :beer:

Didn't you agree earlier in the thread that it's possible to hold a rollerblade stationary on a moving treadmill?

By your distorted view of phisics, that shouldn't be possible! :laugh:

Originally posted by: smack Down
Oh ok, I was think rolling friction was the point when a object started to slide.

Remind me again: who failed physics?

 

[smack Down]

Wow how did some many people end up in this thread that can't understand the simple concept that when you roll a wheel backwards any object connected to the wheel will also go backwards.

 

[AeroEngy]

Originally posted by: smack Down

Originally posted by: AeroEngy

Originally posted by: smack Down

Originally posted by: AeroEngy
Soemone mentioned they wanted to see a free-body diagram so i created one LINK

You keep talking about torque which would just be the force applied by the treadmill times the radius of the tire. The amount of force is dictated by the friction between the tire and the treadmill surface. This value is easly obtained by a high school level physics equation for rolling friction. Look at the daigram.

Note: All the aircraft data was from an F-16 and can be found on wikipedia. Rolling Friction Coeficient was taken from an ordinary tire form the table in wikipedia(just search for rolling friciton). In the F=m*a equation I had to convert the mass to slugs to make the dimensions consistant. I also only showed the X-componet of all the force vectors because Y-re doesn't matter in this case.

If you assume the tires can slip then the plane would take off. I'm assuming prefect tires.

You are not following what rolling friction means. The tires in the diagram do not slip. They roll over the surface of the treadmill. Any object rolling not sliding over any other object has a rolling frcition coefficient. The force I showed was the force required to roll the tires loaded with the weight of the plane along the surface of the treadmill with Zero slip between the two. If there was slip then I would have to use a sliding friciton coefficient which would be higher. Which would also mean burning rubber everywhere.

I think the reason your imaginary plane won't take off is becuase you have snakes on it.

Oh ok, I was think rolling friction was the point when a object started to slide.

here is the FBD you should have drawn
http://img145.imageshack.us/img145/811/fbdoi9.jpg

There are a couple problems I have with your FBD. First Fengine does not act on the hub of the wheel it acts on the more or less the center of mass of the airplane. Also, you automatically assume the two forces are equal. When Fconveryeer is physically limited to the amount of rolling resistance/friction of the tire.

 

[MrPickins]

Originally posted by: smack Down
Wow how did some many people end up in this thread that can't understand the simple concept that when you roll a wheel backwards any object connected to the wheel will also go backwards.

I am intrigued by your ideas, and wish to subscribe to your newsletter!

Either you are a troll, or you are too dim or stubborn to listen to what people are trying to tell you.

Open your eyes, you'll see your logical fallacy.

 

[sao123]

Originally posted by: smack Down
Wow how did some many people end up in this thread that can't understand the simple concept that when you roll a wheel backwards any object connected to the wheel will also go backwards.

We understand that...

Why cant you understand simple physics...
that the jet engines push against the air and not the treadmill?

 

[smack Down]

Originally posted by: AeroEngy

Originally posted by: smack Down

Originally posted by: AeroEngy

Originally posted by: smack Down

Originally posted by: AeroEngy
Soemone mentioned they wanted to see a free-body diagram so i created one LINK

You keep talking about torque which would just be the force applied by the treadmill times the radius of the tire. The amount of force is dictated by the friction between the tire and the treadmill surface. This value is easly obtained by a high school level physics equation for rolling friction. Look at the daigram.

Note: All the aircraft data was from an F-16 and can be found on wikipedia. Rolling Friction Coeficient was taken from an ordinary tire form the table in wikipedia(just search for rolling friciton). In the F=m*a equation I had to convert the mass to slugs to make the dimensions consistant. I also only showed the X-componet of all the force vectors because Y-re doesn't matter in this case.

If you assume the tires can slip then the plane would take off. I'm assuming prefect tires.

You are not following what rolling friction means. The tires in the diagram do not slip. They roll over the surface of the treadmill. Any object rolling not sliding over any other object has a rolling frcition coefficient. The force I showed was the force required to roll the tires loaded with the weight of the plane along the surface of the treadmill with Zero slip between the two. If there was slip then I would have to use a sliding friciton coefficient which would be higher. Which would also mean burning rubber everywhere.

I think the reason your imaginary plane won't take off is becuase you have snakes on it.

Oh ok, I was think rolling friction was the point when a object started to slide.

here is the FBD you should have drawn
http://img145.imageshack.us/img145/811/fbdoi9.jpg

There are a couple problems I have with your FBD. First Fengine does not act on the hub of the wheel it acts on the more or less the center of mass of the airplane. Also, you automatically assume the two forces are equal. When Fconveryeer is physically limited to the amount of rolling resistance/friction of the tire.

A the force acts on the whole plane including the point listed and b Fconveryeer isn't limited to anything. Lets see a proof that the force from wheels is limited to the rolling resistance.

So lets look at it energy wise KE_rotational = 1/2 I * w^2 where w is the angular velocity. So clearly it takes more energy to change the angular velocityof a wheel that is going fast.

 

[smack Down]

Originally posted by: sao123

Originally posted by: smack Down
Wow how did some many people end up in this thread that can't understand the simple concept that when you roll a wheel backwards any object connected to the wheel will also go backwards.

We understand that...

Why cant you understand simple physics...
that the jet engines push against the air and not the treadmill?

What difference does it make. The answer is none.

 

[Toastedlightly]

my offer still stands. Someone from the University of Minnesota Twin cities bring a camera, and we'll do this w/ my toy plane.

 

[sao123]

Originally posted by: smack Down

Originally posted by: sao123

Originally posted by: smack Down
Wow how did some many people end up in this thread that can't understand the simple concept that when you roll a wheel backwards any object connected to the wheel will also go backwards.

We understand that...

Why cant you understand simple physics...
that the jet engines push against the air and not the treadmill?

What difference does it make. The answer is none.

and you can prove this right?

 

[randay]

hes trolling btw if you haven't noticed.

 

[smack Down]

Originally posted by: sao123

Originally posted by: smack Down

Originally posted by: sao123

Originally posted by: smack Down
Wow how did some many people end up in this thread that can't understand the simple concept that when you roll a wheel backwards any object connected to the wheel will also go backwards.

We understand that...

Why cant you understand simple physics...
that the jet engines push against the air and not the treadmill?

What difference does it make. The answer is none.

and you can prove this right?

Sure if
F=ma
if a car applies force X and it has a mass of Y it will have a = X/Y. If a jet applies force X and has mass Y it will have a = X/Y

If the two have the same acceleration then they will have the same speed.

 

[sao123]

Originally posted by: smack Down

Originally posted by: sao123

Originally posted by: smack Down

Originally posted by: sao123

Originally posted by: smack Down
Wow how did some many people end up in this thread that can't understand the simple concept that when you roll a wheel backwards any object connected to the wheel will also go backwards.

We understand that...

Why cant you understand simple physics...
that the jet engines push against the air and not the treadmill?

What difference does it make. The answer is none.

and you can prove this right?

Sure if
F=ma
if a car applies force X and it has a mass of Y it will have a = X/Y. If a jet applies force X and has mass Y it will have a = X/Y

If the two have the same acceleration then they will have the same speed.

They dont have the same force, and they dont have the same accelleration.

 

[sao123]

Originally posted by: randay
hes trolling btw if you haven't noticed.

he's beyond trolling, he's a moron.

 

[dkozloski]

Don't waste your time arguing with a moron. They drag you down to their level and then beat you with experience.

 

[brikis98]

you really must be trolling at this point. watch this video. it's obviously simplified and doesn't match the setup exactly, but it's damn close. and guess what? the skateboard moves forward without the slightest issue, gaining speed.

in real life the plane takes off. deal with it and stop being so goddamn stupid.

 

[sao123]

Originally posted by: brikis98
you really must be trolling at this point. watch this video. it's obviously simplified and doesn't match the setup exactly, but it's damn close. and guess what? the skateboard moves forward without the slightest issue, gaining speed.

in real life the plane takes off. deal with it and stop being so goddamn stupid.

Good demonstration... tho if the runway was longer the point would be proven.

 

[brikis98]

Originally posted by: sao123

Originally posted by: brikis98
you really must be trolling at this point. watch this video. it's obviously simplified and doesn't match the setup exactly, but it's damn close. and guess what? the skateboard moves forward without the slightest issue, gaining speed.

in real life the plane takes off. deal with it and stop being so goddamn stupid.

Good demonstration... tho if the runway was longer the point would be proven.

heheh, yeah, i didn't make the video, but it's a nice effort anyway.

hell, you can see the same effect by putting a hot wheels on a piece of paper towel and pulling the paper towel quickly. since a hot wheels has no drive train, the wheels are free spinning and the car will more or less stay put...

 

[randay]

The skateboard DOES NOT TAKE OFF!!!

 

[jagec]

Originally posted by: brikis98
you really must be trolling at this point. watch this video. it's obviously simplified and doesn't match the setup exactly, but it's damn close. and guess what? the skateboard moves forward without the slightest issue, gaining speed.

in real life the plane takes off. deal with it and stop being so goddamn stupid.

I love the "suck it!" at the end.:laugh:

Yes, in real life the plane takes off with no issues at all. The only way the plane would be kept from taking off in real life is if the brakes were locked, which would be stupid.

 

[smack Down]

Originally posted by: sao123

Originally posted by: smack Down

Originally posted by: sao123

Originally posted by: smack Down

Originally posted by: sao123

Originally posted by: smack Down
Wow how did some many people end up in this thread that can't understand the simple concept that when you roll a wheel backwards any object connected to the wheel will also go backwards.

We understand that...

Why cant you understand simple physics...
that the jet engines push against the air and not the treadmill?

What difference does it make. The answer is none.

and you can prove this right?

Sure if
F=ma
if a car applies force X and it has a mass of Y it will have a = X/Y. If a jet applies force X and has mass Y it will have a = X/Y

If the two have the same acceleration then they will have the same speed.

They dont have the same force, and they dont have the same accelleration.

And why can't they apply the same force?

 

[travisray2004]

Does anyone have a spare treadmill and a spare aireplane, lets see if it reallly would work.. Im thinking that if it does get lift, how does it keep it, since there isnt thrust. I dunno i may be mistaken, or missed a thread. In any case, anyone got a spare... Lets put it on MythBusters.. LOL

 

[sao123]

Originally posted by: smack Down

Originally posted by: sao123

Originally posted by: smack Down

Originally posted by: sao123

Originally posted by: smack Down

Originally posted by: sao123

Originally posted by: smack Down
Wow how did some many people end up in this thread that can't understand the simple concept that when you roll a wheel backwards any object connected to the wheel will also go backwards.

We understand that...

Why cant you understand simple physics...
that the jet engines push against the air and not the treadmill?

What difference does it make. The answer is none.

and you can prove this right?

Sure if
F=ma
if a car applies force X and it has a mass of Y it will have a = X/Y. If a jet applies force X and has mass Y it will have a = X/Y

If the two have the same acceleration then they will have the same speed.

They dont have the same force, and they dont have the same accelleration.

And why can't they apply the same force?

Because the simple High School equation of F=MA does not accurately describe the transfer of a force from a linear acceleration through into a free rotating radial device and then transferring it to cause another linear acceleration. this calculation is far more complex than that simple equation.

 

[msparish]

smack Down...maybe this will help you understand what is going on. Say you have the plane on the treadmill, and the plane is attached to two towing vehicles (e.g. really big trucks). These trucks are not on the treadmill, but the normal ground. Take the trucks and start to pull forward, what happens? The plane moves forward even if the treadmill is moving back! The wheels on the plane are free spinning, so they will spin at what ever speed they need to for the plane to move forward at the same speed as the trucks.

For example, say the trucks are pulling forward at 10mph and the treadmill moves back at 10mph. The plane will move forward at 10mph, and the wheels will spin at 20mph. If trucks pull forward at 20mph and the treadmill moves back at 20mph, the wheels will spin 40mph and the plane still moves forward at 20mph.

The jet engines on the plane are analagous to the trucks (only the jet engines are much, much more powerful). In both cases, they are both "gripping" something other than the treadmill (the trucks grip the non-moving pavement, the jet engines grip the air). Therefore, the treadmill has no practical effect. The wheels will increase their rotation speed so that the plane is still moving forward due to the thrust from the engines. If you accept that the trucks can pull the plane forward, then you must accept that the jet engines can move the plane forward as well.

 

[AeroEngy]

If it wil make anyone happy I think I can explain with real physics equations and revise my free body diagram to take into acount the rotational mass of the tires, the angular acceleration of a realistic tire mass, and the total mass of the aircraft accelerating linearly. I will diagram this better later bu the jist is:

Sum of the Forces = m*a + I*alpha.

I is the moment of inertia of the tires and alpha is the angular acceleration of them. I left this term off in my earlier diagram simplifiing the problem. I will add it back in but i don't think it will make that much of a difference the plane will still take off. Give me a few hours once I get home and it won't take me to long to work it up