Design changes can cost 1,000 and 10,000 times more at the LRIP and final production phases, respectively, than the same change would during product design. As a result, cost increases at the early stage (for reliability downstream) can in most cases be justified.
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Incorporate the emerging technologies identified in Table H-3 into the Defense Technology Objectives and the Defense Technology Area Plan.
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Encourage more research into low Reynolds number flight regimes.
Just as UA come in many categories, so too do the flight environments in which they operate. As a result, Reynolds number effects must be better understood to provide insight into such areas as (1) steady and unsteady flow effects, (2) three-dimensional laminar/turbulent flow transition, and (3) ideal airfoil and wing geometries at Reynolds and Mach numbers which encompass the spectrum of UA flight profiles.
Investments in low Reynolds number engine components are also critical. Turbo machinery for UA at low speeds or high-altitudes face flight environments which are different than those to which modern propulsion has traditionally catered. Heat rejection, turbine and compressor tip losses, and low dynamic pressures are a few of the factors which can degrade the performance of a small propulsion system at these low Reynolds number conditions.
. Investigate the potential role of advanced materials and structures for enhancing UA reliability and availability.
High temperature materials and light-weight structures can offer significant weight savings for UA airframes. On the horizon, smart materials such as shape memory alloys will offer alternatives to the servos, flight control surfaces, and even de-icing systems of existing aircraft designs, which in turn will reduce components count and increase reliability.
. Incorporate and/or develop all-weather practices into future UA designs.
Icing has been a primary factor in at least two Hunter mishaps and three Predator losses. UA cold weather tolerance, as well as operation in precipitation and suboptimal wind conditions, should be a focus for UA designers to enhance UA reliability and availability in real world operations.
Improving UA reliability is the single most immediate and long-reaching need to ensure their success. Their current levels of reliability impact their operational utility, their acquisition costs, and their acceptance into airspace regulations. The value of making reliability improvements must be weighed against not only acquisition cost, as is traditionally the case, but also against the less quantifiable returns to be gained by a commander. As a critical resource to the commander, UA must be available when they are called upon and have the ability to operate freely and respond quickly in any airspace. The recommendations of this study are structured to ensure that this occurs.
APPENDIX H – RELIABILITY
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