Unmanned aerial vehicles, or UAVs, flown for medical resupply missions by the military can bring meaningful benefits to a blood supply network that is large and complex. The authors assess the utility and design of autonomous UAVs — specifically, small fixed-wing aircraft — and search for an optimal fleet design by examining payloads and cost models for two missions: logistical resupply and emergency delivery of blood.
- Does transport on small UAVs degrade blood quality?
- What is the required capability of a blood delivery UAV, and what is the best UAV design for delivering this capability?
- What are the mission parameters that drive this design?
- What makes UAVs especially valuable for performing this mission and for alleviating logistical strain in the blood supply network?
- When considering life-cycle costs, is a fleet of one-size-fits-all UAVs — craft that perform both logistical and emergency blood delivery missions — better than a fleet of mission-specific UAVs?
Autonomous unmanned aerial vehicles (UAVs) are proliferating in both commercial and military markets. Blood makes for an interesting UAV delivery case study because blood products (whole blood, red blood cells, and platelets) have a finite shelf life and unique constraints regarding how they must be transported and stored. The medical community's blood supply chain can potentially benefit from a pairing with a delivery platform that allows for on-demand capability and greater flexibility.
In this report, the authors assess the utility of autonomous UAVs — specifically, small fixed-wing UAVs — for two distinct military missions of interest to the Joint Staff: logistical resupply of blood units to medical treatment facilities and emergency delivery of whole blood to traumatically injured personnel at forward-operating locations in medical situations where time is critical. The authors define a notional blood delivery mission space in terms of distances, payloads, and response times and then detail the use of a modeling software tool they developed to optimize the design of a fleet of blood delivery UAVs. Their assessment tool and specific optimization formulation (geometric programming) reveal the many supply chain issues of importance and relevance to the Joint medical community and advance the understanding of the requirements, capabilities, and cost drivers of small UAV delivery systems.
- For civilian blood delivery, battery-powered UAVs are being used with success. Hospitals in Rwanda make use of these systems so that blood storage centers can quickly distribute blood units to more-remote medical facilities, bypassing slower and less-reliable transportation infrastructure.
- Autonomous UAVs offer similar advantages in making the military's blood supply network more resilient. UAVs can directly connect more-remote blood collection or storage locations to medical treatment facilities and quickly redistribute blood in theater in the event of a spike in demand.
- Fixed-wing UAVs are inherently more efficient and typically capable of carrying larger payloads and traveling longer ranges when compared with quadcopters, making them the most logical design choice for this mission.
- Energy-efficiency and cost comparisons between the baseline battery-powered UAV and a gas-powered craft flying the same missions show that, although the overall efficiency of the electric UAV is higher, the gas-powered platform is lighter, implying a lower unit cost.
- The optimized design of a one-size-fits-all UAV is the better (i.e., lowest cost) option, even though an emergency-specific UAV would achieve lower mission energy costs.
- The one-size-fits-all solution's life-cycle cost is most sensitive to the minimum delivery range of the logistical resupply mission. The life-cycle cost of the emergency blood delivery platform is most sensitive to the heat transfer parameters that contribute to the weight of the payload.
- To maximize UAV utility for blood delivery missions, additional sensitivity studies of extreme temperatures and faster deliveries are recommended. Different payload models should be studied, and some underlying physics models, in particular structural and weight models, should be revisited so that the tool used in this analysis can be applied to problems beyond small UAV design.
- More detailed assessments should be performed of differences in life-cycle costs for gas- versus electric-powered small UAVs.
- To improve the model that performs the fleet design optimization, future developers should consider alternative formulations of the mission assignment problem or other heuristic approaches.
- The tool should be used at the beginning of potential UAV acquisition programs to understand high-level trends related to cost and to understand these trends very quickly. These preliminary optimized design outputs can then be refined by RAND's current aircraft concept design tool.
- This tool's optimized designs should be compared with existing UAV platforms to determine whether new acquisition programs are even necessary.
Table of Contents
Defining the Blood Delivery Mission Space
Rapid UAV Design Optimization of Fixed-Wing Fleets (RUDOFF) Model
Design of an Autonomous UAV Fleet for Blood Delivery
Conclusions and Future Work
RUDOFF Model Description
User-Defined Inputs for RUDOFF
UAV Fleet Visualization Tool User Manual