Graham E. Dorrington

The Dragonfly Flight Envelope and its Application to Micro UAV Research and Development

Abstract In this paper we present quantitative analysis of three dimensional trajectories of dragonflies under free flight conditions. The trajectories were captured while male insects were engaged in their normal behaviour of combat to protect oviposition sites along a stream. With measurements of speed, acceleration and turn rate of large dragonflies we have the means by which comparative studies can be done against other species and in different environments. Using physical scaling laws we propose a method by which this data set can be used to provide a comparison for larger flapping wing UAV concepts. Our ultimate goal is to provide a robust standard against which flapping wing aircraft performance can be compared so that appropriate evolutionary pressure can also be applied to technological developments, thus freeing resources for truly viable designs.

On flying insect size and Phanerozoic atmospheric oxygen

In a recent article in PNAS, Clapham and Karr (1) related the maximum wing length (MWL) of different Odonatoptera and Orthoptera species to Phanerozoic atmospheric oxygen partial pressure (pO2) as predicted by the GEOCARBSULF model (2). They argued that the MWL data assigned to 10-Myr periods is well correlated with elevated Paleozoic pO2 levels, but that the correlation weakens and is ultimately decoupled during the Mesozoic and Cenozoic. To explain the correlation, they assumed that maximum insect size is constrained by a tracheal oxygen supply limit. To explain the decoupling, they referred to the notion that insect size increase results in reduction of flight maneuverability and increased aerial predation by birds (among others), i.e., a selective pressure against size increase also operates. This convenient mixed hypothesis deserves scrutiny.

Certification and Performance: What Is Needed from an Aviation Fuel?

Some of the standard property requirements of sustainable fuels intended to replace, or be blended with, petroleum-derived aviation turbine fuel (Jet A-1) are outlined, as specified by ASTM 7566, including energy content, density, flash point, viscosity, and thermal stability. Several possible future requirement concessions are also suggested.