Torque required to pull a 737-800

[Sapper]

Any idea how to work out the range of torque required to pull a 737-800?
To start of with need to work out the centre of gravity, with 15-25% of total weight being in the nose.
Any idea how to to this?

(This is not homework btw)

 

[voko]

What does "pull a 737-800" really mean? And what does that have to do with torque?

 

[Sapper]

Sorry. Some person was discussing how a plane's wheels would just spin without moving the plane if you were to affix a motor to a plane -unless the motor can provide a certain amount of torque.

 

[voko]

Airplanes already have motors. But perhaps you mean a motor that would turn the airplane's wheels like in a automobile? Which wheel or wheels would be driven?

The minimum torque required to move the airplane would depend on its overall rolling resistance, which is quite complicated: http://en.wikipedia.org/wiki/Rolling_resistance

 

[Sapper]

The motor would be in the actual front 2 wheels.

 

[etudiant]

There are designs in the preproduction stage that integrate an electric motor into the wheels of jetliners such as the 737-800 to allow them to taxi without using a tug or the main engines. Google 'Wheeltug' for more details on one of the contenders.

 

[Sapper]

Yes. It's actually the chairman of WheelTug that challenged me to figure this out!
Here's a test plane.

 

[russ_watters]

Torque is only relevant to a specific configuration; more generally, you want force. And the force is surprisingly small; guys pull large planes in strongman competitions. And that implies a bigger misconception here about the concept of inertia...

 

[Sapper]

So how would I go about finding the magnitude of force...?

 

[Lsos]

Figure out the rolling resistance of the tires and the weight on them. The weight should be easy to find, the rolling resistance, maybe not so much. You can probably approximate based on maybe truck or bicycle tires' rolling resistances. The force required to get the plane rolling will be the weight x rolling resistance. The torque will be force x tire radius.

 

[cjl]

Sorry. Some person was discussing how a plane's wheels would just spin without moving the plane if you were to affix a motor to a plane -unless the motor can provide a certain amount of torque.

That is definitely incorrect - if the torque was insufficient to move the plane, the wheels wouldn't spin at all, and neither would the motor (which is pretty bad for an electric motor, unless it has built in current limiting in the motor controller). The wheels would only spin without moving the plane if the friction between the wheels and the pavement were insufficient to move the aircraft (for example, if the front wheels were on a sheet of ice).