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mandate constraint. Standoff UA designs need to emphasize the attribute of long endurance in order
to achieve the effect of persistence. If broad area coverage and/or extremely long-range sensor
performance is required, then high altitude capability must also be emphasized. Otherwise altitude
performance should be dictated by the other requirements factors. Additionally, while it is possible to
equip a large UA with an impressive suite of imagery and signals intelligence sensors simultaneously,
the question must be asked if this is the most efficient way to achieve the desired effect. Lastly, while
imagery, signals and measurement sensors generally have performed well in the standoff role, they
face limitations against weak signals and very high resolution imagery requirements. Weak signals
are extremely difficult, expensive and possibly unaffordable for stand-off platforms to collect. These
type sensors should be employed on platforms that can get close to, or over fly the targets, which can
substantially reduce the complexity and cost of the sensing technology used. Alternatively, small UA
could be deployed to get in close and collect the very high resolution imagery and achieve greater
success against the weak signals.
􀂾 Overflight. As discussed above, there are some cases where over-flight for collection purposes are
required. This can occur during peacetime where political conditions support such missions such as,
maritime surveillance, peacekeeping or GWOT, or in combat where a sufficient reduction in hostile
air defenses has occurred. There is no over-arching set of capabilities required for overflight, as there
is in the stand-off or denied access roles. If persistence is desired, then typically this would be
achieved via long-endurance attributes between airframe shaping and engine choice. Altitude would
likely be dictated by the mission equipment being employed. For collections against very faint
signals, or requiring very high degrees of resolution, then medium to low altitude UA are probably
the better choices. However, this introduces weather as a design consideration since medium to low
altitude aircraft must operate in areas often plagued with icing and turbulence. Once again, small UA
should be considered in trade analysis because they can maneuver “under the weather” as well as get
very close and use low cost technology to get high resolution results.
􀂾 Denied access. In limited cases, access to denied areas is required to support combat or national
requirements. Generally this is achieved from space; however it is advantageous to have an airborne
penetrating capability that arrives “unwarned” to prevent an adversary from denying collection due to
the predictable nature of orbiting systems. Previously, the DoD used manned platforms, most notably
the U-2 and SR-71 although many other manned platforms of various types have been used on
occasion. Clearly the disadvantage of manned platforms in a denied access collection role is the
potential for loss of the aircrew and the diplomatic situation that would result (e.g., EP-3 incident).
As a result, UA are better suited to this mission area and have seen limited action in the past (e.g., D-
21 and AQM-34 Firebee drones). In the 1990s, the DarkStar UA system was developed using a
different design philosophy than its predecessors. However, it never reached operational capability.
system was developed and operated in this environment. The DarkStar’s primary platform attribute,
survivability, must be the primary one of any UA designed for use in denied airspace. Generally this
dictates reduced signature with considerations for operating speed and altitude. Designing an ISR
system to operate in the denied environment is more difficult than designing a strike system because
the ISR system will complicate signature reduction by the incorporation of sensor apertures in
numerous places across the platform. The design of such platforms will have to strictly adhere to
system design principles and trades to achieve the desired effect when employed. The 2003 Defense
UAS ROADMAP 2005
APPENDIX A – MISSIONS
Page A-4
Science Board and 2003 Air Force Scientific Advisory Board results both observed that a UA capable
of unwarned collection is needed by DoD.
ISR summary. UA have an established and growing track record supporting the ISR mission area.
Reconnaissance UA have been used to experiment and bridge into other mission areas (such as strike –
see next Section). Endurance will always be a hallmark of the UA design when supporting ISR; however
the “denied access” mission will require some design trades against the endurance principle. The concept
of using miniature UA to conduct collection against weak signals or obtain very high resolution results is
　
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