NASA Scientific and Technical Aerospace Reports

This experimental study investigated the feasibility of applying the concept of a skirtless hovercraft into the production
of an operational vehicle. A 0.255 m diameter prototype was designed, built and tested. An air bearing table was used as a
testing platform, virtually eliminating the influence of friction and providing one degree of freedom for the experiments. Static
tests were performed at various heights and craft configurations, providing a wide range of data for comparison. Lift, torque
and efficiency were measured and calculated for each setting. Pressure and velocity information was also collected at specific
points around the craft when operating at different heights above ground. The results indicate a significant increase in total
lift and efficiency when operating the model at close to the ground heights, in ground effect, compared to the lift produced
by the propeller and motor alone. Even more significant changes were found when comparing the in ground effect results with
the out of ground effect values of lift and efficiency. The study also investigated the use of Coanda nozzles on the peripheral
region of the craft, and found them to be less efficient than straight nozzles with similar size and flow rates. Comparisons
between the experimental results and previous computational fluid dynamic analysis are also made and presented in this study.
DTIC
Ground Effect (Aerodynamics); Ground Effect Machines; Helicopters
20060001888 RAND Corp., Santa Monica, CA USA
American Carrier Air Power at the Dawn of a New Century
Lambeth, Benjamin S.; Jan. 1, 2005; 135 pp.; In English; Original contains color illustrations
Contract(s)/Grant(s): DASW01-01-C-0004
Report No.(s): AD-A440448; No Copyright; Avail.: CASI: A07, Hardcopy
This report presents the highlights of the U.S. Navy’s carrier air performance during the first two major wars of the 21st
century: Operation Enduring Freedom against the Taliban and al Qaeda in Afghanistan in 2001 and 2002 and the subsequent
3-week period of major combat in Operation Iraqi Freedom in early 2003 that finally ended the rule of Saddam Hussein. The
report also addresses ongoing modernization trends in U.S. carrier air capability. In the first war noted above, U.S. carrier air
power substituted almost entirely for land-based theater air forces because of an absence of suitable shore-based forward
operating locations for the latter. In the second, 6 of 12 carriers and their embarked air wings were surged to contribute to the
campaign, with a seventh carrier battle group held in reserve in the Western Pacific and an eighth also deployed and available
for tasking. The air wings that were embarked in the 6 committed carriers in the latter campaign flew approximately half the
total number of fighter sorties generated altogether by U.S. Central Command. As attested by the performance of naval
aviation in both operations, the warfighting potential of today’s U.S. carrier strike groups has grown substantially over that
of the carrier battle groups that represented the cutting edge of U.S. naval power at the end of the Cold War. The research
findings reported herein are the interim results of a larger ongoing study by the author on U.S. carrier air operations and
capability improvements since the end of the Cold War. They should interest U.S. naval officers and other members of the
defense and national security community concerned with the evolving role of U.S. carrier air power in joint and combined
operations. An extensive bibliography is included.
DTIC
Afghanistan; Aircraft Carriers; Iraq; Military Aviation
20060001898 Metron, Inc., Reston, VA USA
Top-Down Mechanism Design Study for Multi-UAV Search and Surveillance
Godfrey, Gregory A.; Oct. 31, 2005; 6 pp.; In English
Contract(s)/Grant(s): W911NF-04-C-0041
Report No.(s): AD-A440491; ARO-47062.2-MA-DRP; No Copyright; Avail.: Defense Technical Information Center (DTIC)
Under this seedling effort, Metron has developed and demonstrated ‘function-driven design’ technology for complex
distributed systems and applied it to an Unmanned Aerial Vehicle (UAV) ground target surveillance scenario. The authors
considered three types of UAV interaction mechanisms (auction/bidding methods, swapping-based methods and local
optimization methods) and two different target motion models (stationary and mobile, random walkers). There are two primary
breakthroughs. The first is a value potential approach to optimizing search paths based on approximating an infinite-horizon
search plan. Using this value potential to dictate UAV motion improves the search performance, especially for disjoint,
multimodal (patchy) probability distributions on target position. The second innovation introduces dynamic area sectoring,
which allows UAVs to partition the search area dynamically and to balance the search workload across UAVs. Sectoring also
eliminates the need to deconflict search paths and simplifies collision avoidance because each UAV stays inside its sector.
Combining the value potential-based UAV motion and dynamic sectoring reduced the median time to target detection by up
to 40 percent in this experimental testing. Based in part on the improved multi-sensor search capability developed under this
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