1.1 Military Interest
1.2 Other Applications
1.3 MAV Requirements
1.4 MAV Configurations
1.5 The Hummingbird Configuration
The Defense Advanced Research Projects Agency
(DARPA) is working on the development of a new class of flight vehicles
called micro air vehicles (MAVs). The high level of current interest in
developing small flight vehicles is the result of the nearly simultaneous
emergence of their technological feasibility and an array of compelling
new military needs, especially in urban environments . Technological
feasibility follows from advances in several micro-technologies, including
the rapid evolution of micro-electromechanical systems, also known as MEMS.
Military needs follow from a shift toward a more diverse array of military
operations and the predicted spectrum of conflict in non-traditional environments
(e.g. urban centers) for 21st-Century warfighters.
The Rand Corp., a research organization, first
raised the possibility of miniature flying vehicles in 1992. They presented
a report to the Pentagon that examined a range of microdevices for defense
applications . Engineers from the Massachusetts Institute of Technology
examined the idea more closely, and enthusiasm for the concept grew. The
outcome of the effort was a newly created DARPA program which was developed
for this new dimension of flight. The DARPA program was initiated through
the agency’s Small Business Innovation Research Program, and in the Fall
of 1997, the research agency began a three-year, $35 million effort to
have industry and academia develop prototypes .
MAVs are not small versions of larger aircraft,
but they are fully-functional, militarily capable, six-degree-of-freedom
aerial robots. Their mobility provides the capability of deploying a useful
micro payload to a remote or otherwise hazardous location where it may
perform any of a variety of missions. Such missions may include reconnaissance
and surveillance, targeting, tagging, and bio-chemical sensing . Initial
missions for MAVs would include reconnaissance and surveillance, but they
also could encompass targeting artillery and mortars, assessing battle
damage, carrying acoustic sensors to listen for the movement of heavy equipment,
and transporting detectors to sense radiation or biological and chemical
Initial development of the MAVs has been spurred
on by military interest in producing miniature intelligence-gathering planes.
The Pentagon hopes that the devices will give small military units direct
access to reconnaissance data. MAVs could help them in battling an enemy
just over a hill or in engaging them in street-to-street fighting in an
urban setting. MAVs are envisioned as an asset at the platoon level or
below giving the individual soldier on-demand information about his surroundings
and for providing increased situational awareness which results in greater
effectiveness and fewer casualties.
Ultimately, MAVs could also be adapted to many
civilian applications including guiding fire and rescue operations, monitoring
traffic, forestry and wildlife surveys, border surveillance, observing
crops, real estate aerial photography, and furnishing information to police
Figure 1.1: An "Over-The-Hill Reconnaissance"
Mission for the MAV 
The U.S. Navy is interested in developing small,
unmanned vehicles to serve in reconnaissance missions too hazardous for
human pilots. MAVs could also serve during wartime in order to determine
if areas are clear of hostile forces as
shown in Figure 1.1. Another possible application of MAVs is in the area
of chemical leak zones. In these situations, it is very important that
the situation be assessed first without the risk of exposure to people.
A danger assessment can be performed with small sensing equipment as a
payload on the MAV.
Additionally, MAVs have fire-fighting applications.
A small, maneuverable MAV with an infrared camera could locate people still
in a building while keeping firefighters safely away from danger. Finally,
an MAV could be a target designator. The MAV could eliminate targets without
involving humans .
The definition employed in DARPA’s program limits
these aircraft to a size less than 15 centimeters (6 in.) in length, width,
or height . MAVs must have a weight of 50 grams or less and must be
capable of staying aloft for 20 to 60 minutes for a distance of 10 kilometers.
The aircraft will have to be light and small enough to fit in a soldier’s
backpack, yet be capable of carrying a solid-state camera, infrared sensor
or radar detector on flights of several kilometers. The MAV would have
to carry out most of its operations autonomously, controlled by an on-board
computer that would use the sensory data collected to fly around hazards
such as trees and buildings. MAVs must carry a power supply that will keep
them in the air long enough to complete their mission, and MAV engines
will have to be powerful enough to propel each aircraft at more than 30
kilometers per hour.
Interest groups from the military, universities,
and private companies have proposed multiple designs of MAVs. These vehicles
may display a wide variety of configurations depending on specific mission
requirements. Design proposals differ in both outward and inward appearances.
Some designs have wings and tails similar to conventional aircraft, while
others take the configurations of tail-less flying wings, oval disks, insects,
or other miscellaneous shapes .
Intelligent Automation Inc. is proposing a conventional
looking aircraft that will be powered by a small piston engine driving
a two-inch propeller. The design uses available technology to develop its
small alcohol-fueled engine. Aerodyne Research Inc. has proposed a spheroid
craft powered by several microturbofan jet engines that fire downward from
its circular bottom. The advantage of a spheroid craft is its ability to
hover in flight gathering reconnaissance data.
Robert Michelson of the Georgia Tech Research
Institute, envisions the MAV as a multi-mode vehicle capable of flying
and crawling. The entomopter design, as seen in Figure 1.2, was inspired
by insects and uses a reciprocating chemical muscle to generate an up-and-down
motion, such as beating wings or scurrying feet.
1.2: Robert Michelson's Entomopter Design 
Figure 1.3: The Micro Air Vehicle
Flight Regime Compared to Existing Flight Vehicles .
The new MAVs could take on several model variations.
Some possible sources include insects, birds, and small aircraft. Ultra
Flite plans to use the hummingbird as their modeling source. First, a hummingbirds’
characteristics make them a perfect candidate for MAV modeling. The most
impressive capability is that it can maintain hovering flight. This would
be especially useful in several MAV applications such as battlefield assessment
and surveillance. Also, hummingbirds are small in size and quiet, which
makes them prime choices for the above applications. Finally, the hummingbird
is a highly efficient system. Their unmatched maneuverability and their
ability to instantly transition between flight modes make hummingbirds
an excellent choice for MAV modeling. Figure 1.3 shows how the hummingbird
is within the perfect range of micro air vehicle design parameters.
The Hummingbird Configuration