# Torque required to pull a 737-800

• Sapper
In summary, the torque required to pull a 737-800 depends on the weight of the aircraft and the surface friction of the runway. The maximum takeoff weight of a 737-800 is 174,200 pounds, and the required torque can range from 20,000 to 25,000 foot-pounds, depending on the runway conditions. This torque is generated by the aircraft's engines and is necessary to overcome the resistance and inertia of the aircraft during takeoff. Additionally, factors such as wind speed and direction can also affect the amount of torque needed to successfully pull the aircraft.
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)

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

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.

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

The motor would be in the actual front 2 wheels.

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.

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

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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...

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

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.

Sapper said:
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).

## 1. What is torque?

Torque is a measure of the force that causes an object to rotate around an axis. It is typically measured in units of Newton-meters (Nm) or foot-pounds (ft-lb).

## 2. How is torque calculated?

Torque is calculated by multiplying the force applied to an object by the distance from the axis of rotation to the point where the force is applied. This can be represented by the equation T = F x d, where T is torque, F is force, and d is distance.

## 3. How much torque is required to pull a 737-800?

The amount of torque required to pull a 737-800 will vary depending on factors such as the weight of the plane, the surface conditions of the runway, and the power of the towing vehicle. However, on average, it is estimated that approximately 200,000 Nm of torque is needed to pull a 737-800.

## 4. Why is torque important in pulling a 737-800?

Torque is important in pulling a 737-800 because it is necessary to overcome the plane's inertia and initiate movement. It also helps to maintain a constant speed and overcome any resistance or friction between the wheels and the runway.

## 5. How can torque be increased when pulling a 737-800?

To increase torque when pulling a 737-800, a more powerful towing vehicle or a longer lever arm could be used. Additionally, reducing the weight of the plane or improving the surface conditions of the runway can also help to decrease the amount of torque needed to pull the plane.

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