Thesis--School of Advanced Airpower Studies, Maxwell Air Force Base, Ala., 1995-96. / Title from title screen (viewed Oct. 9, 2003). "June 1996." Includes bibliographical references.

This thesis examines the suitability of airdrop as a means of resupply for the Canadian Forces (CF) in an attempt to reduce forward supply inventories and promote “zero-footprint” logistics. Research methods involved both quantitative and qualitative techniques, consulting CF manuals and subject matter experts. Based on performance, airdrop staged from rear locations or outside the theatre of operations can meet resupply requirements. Although airdrop has longer assembly and loading times than ground based delivery, flight speed and direct routes can make up the difference. However based on interviews with CF personnel, it appears that due to limited availability of aircraft, drop zone requirements, delivery vehicle vulnerability, and the need for backhaul logistics, airdrop could not be used as a sole means of resupply.

This thesis examines the suitability of airdrop as a means of resupply for the Canadian Forces (CF) in an attempt to reduce forward supply inventories and promote “zero-footprint” logistics. Research methods involved both quantitative and qualitative techniques, consulting CF manuals and subject matter experts. Based on performance, airdrop staged from rear locations or outside the theatre of operations can meet resupply requirements. Although airdrop has longer assembly and loading times than ground based delivery, flight speed and direct routes can make up the difference. However based on interviews with CF personnel, it appears that due to limited availability of aircraft, drop zone requirements, delivery vehicle vulnerability, and the need for backhaul logistics, airdrop could not be used as a sole means of resupply.

Airdrop systems provide a unique capability of delivering large payloads to undeveloped and inaccessible locations. Traditionally, these systems have been unguided, requiring large landing zones and drops from low altitude. The invention of the steerable, gliding, ram-air parafoil enabled the possibility of precision aerial payload delivery. In practice, the gliding ability of the ram-air parafoil can actually create major problems for airdrop systems by making them more susceptible to winds and allowing them to achieve far greater miss distances than were previously possible. Research and development work on guided airdrop systems has focused primarily on evolutionary improvements to the guidance algorithm, while the navigation and control algorithms have changed little since the initial autnomous systems were developed. Furthermore, the control mechanisms have not changed since the invention of the ram-air canopy in the 1960's. The primary contributions of this dissertation are: 1) the development of a reliable and robust method to identify a flight dynamic model for a parafoil and payload aircraft using minimal sensor data; 2) the first demonstration in flight test of the ability to achieve large changes in glide slope over ground using coupled incidence angle variation and trailing edge brake deflection; 3) the first development of a control law to implement glide slope control on an autonomous system; 4) the first flight tests of autonomous landing with a glide slope control mechanism demonstrating an improvement in landing accuracy by a factor of 2 or more in especially windy conditions, and 5) the first demonstrations in both simulation and flight test of the ability to perform in-flight system identification to adapt the internal control mappings to flight data and provide dramatic improvements in landing accuracy when there is a significant discrepancy between the assumed and actual flight characteristics.

With the advent of steerable, ram air parafoil canopies, aerial payload delivery has become a viable alternative for situations involving remote or undeveloped areas, hostile environments, or otherwise inaccessible locations. Autonomously guided systems utilizing such steerable, ram air canopies are typically controlled by symmetric and asymmetric deflection of the canopy trailing edge. Although these systems have demonstrated substantial improvement in landing accuracy over similarly sized unguided systems, their low number of available control channels and limited ability to alter vehicle glide slope during flight makes them highly susceptible to atmospheric gusts and other unknown conditions near the target area. This research aims to improve landing accuracy in such adverse conditions by replacing the standard trailing edge deflection control mechanism in favor of upper surface canopy spoilers. These spoilers operate by opening several spanwise slits in the upper surface of the parafoil canopy thus forming a virtual spoiler from the stream of expelled pressurized air. In particular, estimation of steady-state vehicle flight characteristics in response to different symmetric and asymmetric spoiler openings was determined for two different small-scale test vehicles. Additionally, improvements in autonomous landing accuracy using upper surface spoilers in a combined lateral and longitudinal control scheme was investigated computationally using a high fidelity, 6-DOF dynamic model of the test vehicle and further validated in actual flight experiments with good results. Lastly, a novel in-canopy bleed air actuation system suitable for large-scale parafoil aircraft was designed, fabricated, and flight-tested. The in-canopy system consists of several small, specifically designed wireless winch actuators mounted entirely inside the parafoil canopy. Each in-canopy actuator is capable of opening one or more upper surface canopy spoilers via a unique internal rigging structure. This system demonstrates not only the applicability of bleed air spoiler control for large-scale autonomous parafoil and payload aircraft, but also provides the potential for significant savings in size, weight, and cost of the required actuation hardware for currently fielded systems.