Do planes use thir wheels to move forward like a car does?
Mythbusters plan to uncover plane on conveyor belt
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Last: 5 yr ago by toucan82
Regardless of the propulsion method used, it's dependent on the conveyor belt system and driver.
quote:
It really depends on who's "driving" the conveyor belt system.
Just for argument's sake: Ditka.
Then the conveyer belt wins.
What about if Scott Derry were "driving" said conveyor belt system?
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Unless the wheels can move the airplane forward, the airplane will stay stationary!!!!! This is the fundamental misunderstanding everyone has about airplanes....
Ditka is moot!
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Ditka is moot!
HORN! I SEES YOU!
Plane view?
excellent form
III Horn is an excellent conveyor of humor...
gambochaman
Joined:
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How long do you want to ignore this user?
The conveyor is moot!
Wait ....
Wait ....
quote:
Do planes use thir wheels to move forward like a car does?
Well...duh!!!
Of course...You should see how fast those little suckers spin on the SR-71...
SR-71
SR-71 is moot
gotcha IIIH...
X-15 
Aurora!
areola!
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SR-71
Retired.
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areola!
What does "The Little Mermaid" have to do with planes and conveyor belts?
Well..areola is NOT moot, I can tell you that!!!!
quote:
Ff = uN where u is itty bitty...and N ~= W
So, THAT can't be it...
close..., but Ff=uN is the equation for static friction...
since we're dealing with rolling resistance, velocity has to be in the equation...rolling resistance basically boils down to the work that must be done to change the shape of the tire (remember that a tire is not round when carrying a load...that's why they get hot), and the kinetic friction in the wheel bearings.
Rr[lbs] = r[lbs*s/ft]V[ft/s]
r is going to be very low...for a car it is around .03...an airplane will be similar, however, r will decrease as lift increases. As low as r is starting out, V can become great enough to make Rr[lbs] = engine thrust [lbs]
and when the forces = 0...there is no change in motion.
keep in mind, the axles and the conveyor will fail catastrophically first.
Que????
Ff = uN
Pick your type of friction, then you get the u for that type of friction, determine its weight and viola.
Velocity doesn't play into it...
For rolling friction...
So...apparently the conveyor and axles aren't the only thing that fails with your post...
On another note, you need that rolling friction so that the wheels can provide the propulsive force to get the aircraft to fly...
On another, only tangentially related note, helicopters maneuver by flapping their rotors...
[This message has been edited by Ag with kids (edited 12/27/2007 9:47p).]
Ff = uN
Pick your type of friction, then you get the u for that type of friction, determine its weight and viola.
Velocity doesn't play into it...
For rolling friction...
So...apparently the conveyor and axles aren't the only thing that fails with your post...
On another note, you need that rolling friction so that the wheels can provide the propulsive force to get the aircraft to fly...
On another, only tangentially related note, helicopters maneuver by flapping their rotors...
[This message has been edited by Ag with kids (edited 12/27/2007 9:47p).]
Crr includes velocity...
hth
EDIT:
the difference between sliding and rolling is that when two surfaces are sliding against eachother like in all of the block on a ramp problems (the ones without the elephants at least) the block is sliding, the block can slide as fast as it wants, the force from friction is constant as long as it keeps moving...
when you have a tire rolling, you are doing work to deform the tire, and work to create sound from vibrations of the tire, and work to create heat in the tire...
the faster the tire spins, the faster this work is done, the more power is required to do it.
even in the block sliding down a ramp problems you did in physics 218 you always had to assume that the system was 100% efficent and no potential energy was lost to the creation of heat. The fact is, the faster that block slides, the more heat is created from the friction...
[This message has been edited by TexasRebel (edited 12/27/2007 10:03p).]
hth
EDIT:
the difference between sliding and rolling is that when two surfaces are sliding against eachother like in all of the block on a ramp problems (the ones without the elephants at least) the block is sliding, the block can slide as fast as it wants, the force from friction is constant as long as it keeps moving...
when you have a tire rolling, you are doing work to deform the tire, and work to create sound from vibrations of the tire, and work to create heat in the tire...
the faster the tire spins, the faster this work is done, the more power is required to do it.
even in the block sliding down a ramp problems you did in physics 218 you always had to assume that the system was 100% efficent and no potential energy was lost to the creation of heat. The fact is, the faster that block slides, the more heat is created from the friction...
[This message has been edited by TexasRebel (edited 12/27/2007 10:03p).]
All that stuff posted above...
moot.
moot.
gooses are moot!
quote:
Crr includes velocity...
Crr is the coefficient of rolling resistance.
It is a constant, regardless of velocity.
I do agree with the fact that nothing is 100% efficient in the real world, though...
And PSU is moot!!!!
Ag with Kids,
when you look up the Crr for a rolling object, the table that you will find it on will have Velocity included...
simply, you will find the Crr for a certain velocity, for the type of wheel in question...
when you look up the Crr for a rolling object, the table that you will find it on will have Velocity included...
simply, you will find the Crr for a certain velocity, for the type of wheel in question...
The tables I can find on the innerwebtron don't have V.
BTW...your original equation also needs something else. Friction calculations w/o N don't yield very big numbers...or the right units...
And the r in your equation won't get smaller with lift - the N will...
[This message has been edited by Ag with kids (edited 12/27/2007 10:48p).]
BTW...your original equation also needs something else. Friction calculations w/o N don't yield very big numbers...or the right units...
And the r in your equation won't get smaller with lift - the N will...
[This message has been edited by Ag with kids (edited 12/27/2007 10:48p).]
the r in my equation will because my r is assuming a constant normal force with a varying velocity...
the Crr in yours is assuming a constant velocity with an independant normal force.
in the case of an airplane, both velocity and normal force change...
Edit: since the mass of the plane doesn't change without lift, r includes the normal force, N.
[This message has been edited by TexasRebel (edited 12/27/2007 10:55p).]
the Crr in yours is assuming a constant velocity with an independant normal force.
in the case of an airplane, both velocity and normal force change...
Edit: since the mass of the plane doesn't change without lift, r includes the normal force, N.
[This message has been edited by TexasRebel (edited 12/27/2007 10:55p).]
That's cool...
I got an Aero degree...the only reason we learned about wheels is because we had to know how they propelled airplanes when they fly...
I got an Aero degree...the only reason we learned about wheels is because we had to know how they propelled airplanes when they fly...
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