FBN Bumblebees

Bumblebees can’t fly?

Obviously bumblebees can and do fly. Calculations based on fixed-wing studies or simplified linear oscillating airfoil wings fail to show how enough lift can be generated to get the huge mass of a bumblebee, compared to its wing size, off the ground. That's not surprising because the bumblebees' wings are not fixed, but moving. They are also not simple airfoils like an airplane wing and they don't move in a simple way. A number of studies have been conducted to try to understand this bee's unique method of flying.

Learning how bumblebees fly requires taking into consideration the roughness and flexibility of their wings. Bumblebees actually have 4 wings with a larger pair in front and a smaller pair in back fastened to the front wings by a series of tiny hooks. As the wings move, they bend and create air flow separation and an effect called dynamic stall which results in a large air vortex above the wing. These vortices provide greater lift with minimal energy.

Don't think the flight of the bumblebee doesn't take much energy. The bee's wings beat 130 or more times per second. The flight muscles which power the wings are large for the bee's size, taking up almost the entire volume of the thorax, the mid-section of the bee. In fact, the buzzing you hear is not the beat of the wings, but the pulsing vibration of the powerful flight muscles. Scientists have found that bumblebees still buzz when their wings are removed.

In cooler temperatures, the bumblebee has to warm up before flying. It cannot fly unless its wing muscle temperature is 86 degrees. When the surrounding temperature is cooler, the bumblebee shivers to raise its wing muscle temperature before it can take off. Depending on air temperature and the bee's temperature (such as sitting in the sunshine) it may take a few seconds up to 15 minutes to raise the temperature enough to take off. In the meantime, the bee is sort of sitting on the runway waiting for clearance.