How much thrust does a ceiling fan produce?

Summary

In this humorous and experimental video, the creator explores how much thrust a ceiling fan generates by measuring the weight reduction of different fans while they're in operation. Through tests with fans from Menards, Envirofan, and even a commercial heat recovery fan, the video delves into the physics behind ceiling fan thrust, torque, and airflow. Although the thrust produced is relatively small, the experiments reveal intriguing insights into how ceiling fans affect their mounting structures. The video combines technical details with humor, making it both educational and entertaining for viewers curious about everyday objects and their hidden forces.

Takeaways

• 😀 Ceiling fans can produce measurable thrust, although it's not much—typically around 0.5 to 1 pound.
• 😀 The thrust generated by a ceiling fan is caused by the air it pushes down, creating an equal and opposite reaction that 'lightens' the fan slightly.
• 😀 The torque produced by the motor in a ceiling fan can distort thrust measurements, especially during startup and shutdown.
• 😀 A cheap Menards ceiling fan was found to lose about 0.46 pounds (209 grams) of weight when running at full speed.
• 😀 A higher-quality fan, like the Envirofan Gold Line, produced nearly 1 pound of thrust (470 grams or 4.6 newtons) at full speed.
• 😀 Running a fan in reverse (blowing air upwards) causes the fan to get heavier, as it doesn’t generate as much downward thrust.
• 😀 The Emerson Heat Fan, designed for commercial use, also produces about 1 pound of thrust (or up to 1.36 pounds), despite being intended for heat circulation.
• 😀 Fans with built-in heaters, like the strange 1980s model tested, produce less thrust compared to regular ceiling fans, around 0.7 pounds (322 grams).
• 😀 The thrust produced by ceiling fans, while measurable, is unlikely to significantly affect the structural integrity of the ceiling mount or electrical box.
• 😀 The thrust from a ceiling fan is insignificant compared to the torque forces it generates, particularly during startup and when the motor is in operation.

Q & A

What inspired the video on ceiling fan thrust?

The creator was curious about the forces produced by ceiling fans and whether these forces, particularly thrust, have any measurable impact on the fan's weight or operation.

How does a ceiling fan generate thrust?

A ceiling fan generates thrust by pushing air downward, creating an opposite reaction that theoretically causes the fan to become lighter as air is pushed away.

What is the main difference between a ceiling fan and an airplane propeller?

An airplane propeller generates significant thrust to propel the airplane, while a ceiling fan produces much less thrust, primarily intended for air circulation to cool a room.

How much thrust does a typical ceiling fan produce?

A typical ceiling fan produces between half a pound and a full pound of thrust, depending on the quality and design of the fan.

What was the method used to measure the thrust of ceiling fans in the video?

The thrust was measured using a crane scale to weigh the fan before and after it reached full speed. The change in weight was attributed to the thrust generated by the fan.

Did the fan’s weight decrease when running at high speed?

Yes, the fan's weight did decrease slightly when it was running at full speed. For example, the Menards fan lost about 0.46 pounds (209 grams) when operating at high speed.

What is the significance of the torque produced by the ceiling fan?

The torque generated by the fan motor causes a twisting force that can skew the scale's weight readings. This effect needs to be considered when measuring the fan's actual weight change due to thrust.

How do dual-rotor helicopters relate to ceiling fans?

Dual-rotor helicopters are similar to ceiling fans in that they use rotating blades to produce lift (thrust). The difference is that dual-rotor helicopters have two rotors spinning in opposite directions to cancel out the twisting torque, which makes them easier to control.

Why do some ceiling fans have a reverse function?

Ceiling fans have a reverse function to help circulate warm air in the winter. When running in reverse, the fan blows air upward, reducing temperature gradients by pushing the warm air trapped near the ceiling back down.

How did the Emerson Heat Fan perform in the thrust test?

The Emerson Heat Fan, a commercial fan designed for high ceilings, produced about 1 pound (around 450 grams) of thrust when operating at full speed, with slight variations in the weight readings due to potential scale inconsistencies.