Unmanned Aircraft Systems Roadmap 2005-2030 - Federation of ...

UAS ROADMAP 2005
specific fuel consumption. VAATE also emphasizes improvements to installed performance,
addressing overall performance improvements in addition to engine component technologies.
• VAATE is a two-phase program with specific goals. By the end of phase 1 in 2010, a six fold
improvement in affordability will be demonstrated, and at the end of phase 2 in 2017, a ten-fold
improvement in affordability will be demonstrated. Baselines for the effort are current state-ofthe-art
power plants such as the Honeywell F124 used in the Boeing X-45A UCAV
Demonstrator.
• VAATE work will be concentrated into three focus areas and two pervasive areas. Focus areas
will include durability; work on a versatile core, and intelligent engine technologies. Pervasive
areas, which are really incubators for hatching ideas that should be included in the VAATE focus
areas, will be segregated into the categories of high-impact technologies and UA.
Propulsion – Internal Combustion
Reciprocating internal combustion gasoline engines are widely used in fixed wing UA with take-off gross
weights less than 2,000 pounds. This is true among legacy UA, (Pioneer, Shadow 200, and Predator) and
numerous demonstration aircraft from both industry and government laboratories where two and four
cycle engines are used. While either cycle offers advantages and disadvantages, the demonstrated lower
cost and better efficiency of these engines precludes developing turbo-shaft engines to meet the engine
needs for UA in these size classes. However, these engines do not meet the requirements for a common
battlefield fuel as defined in DoD 4000. In addition, the engines tend to fall short in reliability/durability
as compared to man-rated aircraft engines, making them less attractive to warfighters who rely heavily on
the data received from their UA payloads to make real-time decisions. Future small UA will continue to
utilize these low cost, gasoline engines unless significant advances are made. Two potential areas are
weight reduction for true diesel cycle engines and successful modification of existing gasoline engines to
burn jet propellant (JP) fuels with increased reliability.
True diesel cycle engines had been precluded up to this time due to significantly higher engine weight as
compared to most gasoline engines. However, the advent of turbo-diesel technologies over the last few
decades, along with continuing development work with engine manufacturers to reduce the weight of
diesel engines has advanced the possibility of diesel engines being used by light aircraft. For example,
the Thielert Group in Germany has worked for many years to qualify several of their engines with the
European Aviation Safety Agency (EASA), for use in general aviation aircraft. Their efforts have
recently proven fruitful with certifications to operate their Centurion 1.7 engine on Cessna 172 aircraft,
and soon this same engine will be certified for the Piper Warrior III. Both the government and industry
are already evaluating an application of this type on the MQ-1 Predator to determine what “actual”
performance results would be realized when installed.
Technology outlook. The use of both motor gasoline and aviation gasoline in small UA is undesirable,
because it is both unsafe (JP fuels have higher flashpoints than gasoline, making them more tolerant of
explosive combustion situations) and logistically difficult to support. There are currently several ongoing
efforts to develop small JP5/8 fuel burning engines in the power classes and power to weight ratios being
discussed here, including lightweight versions for aviation applications. For example, the opposed
cylinder (OPOC) engine development program (FEV Engine Technology, Inc.) is developing a light
weight, high powered diesel engine that is being sized for the A160. In addition, Nivek R&D, LLC, is
developing a lightweight six-cylinder diesel engine for the A-160.
� Reliability. Reliability of current low cost two and four-cycle UA engines are on the order of a few
hundred hours, sometimes less. This shortcoming, when compared to turbine engines, is often
overlooked due to the low cost of reciprocating engines. However, good engine reliability has proven
to be a significant factor in user acceptance of UA. Nevertheless, most UA demonstrations, and even
development programs do not stress reliability in the design process, nor prove reliability in their
development, many times resulting in disappointing results in extensive flight and operational testing.
APPENDIX D – TECHNOLOGIES
Page D-3