Biomedical Engineering Reference
In-Depth Information
Microcraft OAV (1500 gm)
MicroSTAR (110gm/25 min)
MICOR [100g/3 min]
LuMAV [440g/5-10 min]
1000
Weight (gm)
100
Objective
[100g/60 min]
10
0
10
20
30
40
50
60
Microbat [10g/5 min]
Endurance (min)
Black Widow [80g/22 min]
FIGURE 5.10
Mass and performance of typical MAVs. Adapted from Ref.
45
. D.J. Pines and F. Bohorquez, Challenges
facing future micro-air-vehicle development, Journal of Aircraft, Volume 43, 290-305, SPIE 2006.
The ability to hover as well as fly efficiently at
low speeds is crucial for a microflyer designed for
indoor surveillance. Accordingly, a large amount
of research has been focused on rotary-wing and
flapping-wing microflyer configurations. Some
unconventional hover-capable configurations
have also been proposed. The hover-capable
microflyers are described in more detail in the
following sections, considering that hovering
flight itself is inspired by biological flyers.
flight is a solution favored by millenia of evolu-
tion and hence must be the most efficient. Other
researchers have pointed out that it is impossi-
ble to realize in nature a high-speed rotary joint
such as that required for a rotor shaft. This pre-
cluded the evolution of any natural rotary-wing
flyers and therefore questions the superiority of
flapping-wing flight.
Hall and Hall
[46]
developed a variational
method to predict the circulation distribution on
flapping wings that would yield the minimum
power required for a given thrust and lift. This
study concluded that the efficiency of flapping-
wing flight is not necessarily greater than that of
propeller-driven flight at low Reynolds numbers.
Ellington and Usherwood
[47]
measured the
performance of rotors at a Reynolds number
range 10,000-50,000. They studied three types of
blade planforms: a linear taper, the same
planform as a hawkmoth wing, and a smooth
5.5.1 Comparison of Rotary-Wing and
Flapping-Wing Flyers
There has been a long-standing debate over
whether rotary-wing flight or flapping-wing
flight is more efficient at the microflyer scale.
Many researchers have claimed that the exis-
tence of flapping-wing natural flyers in the size
range of microflyers indicates that flapping-wing
