Aerodynamics and control in insect flight

Richard J Bomphrey

X ray; muscle physiology suite; GPS & IMU loggers; pressure measurement; force plates; bumpy treadmills; EMG; MRI; micro-CT; robotics; VR; light aircraft; flow tunnels;

The Structure and Motion Laboratory>800 m2 (and 600 m2 more this year)

Early days

aerodynamic forces

3D locomotion

rich sensory

input

neural control

activate muscles

wing morphology and kinematics

Insect flight as a model system

movie: J. Zeil

1979

900 stereo pairs

2500 bubble images in each stereo pair

5 stereo pairs fully analysed

1984

2005Tobacco hawkmoth vortex wake over a wingbeat cycle.

The flow around the wings and thorax of Manduca sexta in late downstroke.

The four classes of leading-edge vortex described to date.

Bomphrey et al 2005Warrick et al 2005Muijres et al 2008Lentink et al 2009

Hawkmoth: Fruit fly:Bat:Hummingbird:

65%45%40%15%

Leading-edge vortices in biology

Walker et al JRS: Interface (2009)Young et al Science (2009)

Kinematics of the desert locust

Walker et al JRS: Interface (2009)Young et al Science (2009)

Kinematics of the desert locust

• CFD validated with close match

• Qualitative and quantitative agreement with full-fidelity model

• Kinematic parameters changed to test corrugation, twist, and bending in the wing…

CFD PIV smoke

Young et al Science (2009)

do

wn

was

h m

s-1

CFD of the desert locust

0.88 N/W 0.51 N/W

Full-fidelity Flat plate

• Fully deforming wings have better power economy.

• If locusts evolved from an ancestor with rigid wings, their subsequent compliance has inhibited leading-edge separation and improved lift power economy by approx. 70%

• This stems from a number of sources, including:• CAMBER MODULATION• REDUCED SEPARATION at the leading edge• modulation of spanwise ANGLE OF ATTACK

Young et al Science (2009)

CFD of the desert locust

Hoerner & Borst (1987)

Lift

Spanwise CL

Planform

Downwash angle

Span efficiency

ei=0.89

Span efficiency

Span efficiency: tr-PIV

Ever increasing detail of model species tells us relatively little compared with identifying trends and overarching themes.

Six species of hawkmoth

Six species of hawkmoth

Advance ratio

Normalised lift

Six species of hawkmoth

Bomphrey R J et al Phil Trans Roy Soc B ( invited for 2016)

Six species of Odonata

P. Henningsson (photo: A. Hedenström)

Swift aerodynamics

Swift aerodynamics

Henningsson, Hedenström and Bomphrey 2013

sensory systems

Aircraft vs Insect sensory systems

F-35 Joint Strike Fighter

In contrast, insect sensory systems are highly non-orthogonal

Compound eyeKevin McKenzie, University of Aberdeen

Fly wing hairswww.bugscope.itg.uiuc.edu

Haltereswww.ento.csiro.au

Aircraft vs Insect sensory systems

BBC

Optic Flow

Krapp, 1996Mode Sensing Hypothesis: Krapp, Taylor & Humbert, 2012

Optic Flow

1. Glide: stable

2. The Phugoid- unstable oscillatory modeexchange of kinetic and potential energy

3. Banked Turn; Spiral mode- unstable divergent mode

..there are others

Trade-off Modes of motion

Flight control – two concepts

How is the flight control related to flight dynamics?

© Charles W. Melton

What visual information is important to insects for controlling their flight?

Flight control: example questions

Windsor, Bomphrey and Taylor, 2013

Variable Gain to stabilise

forward velocity 0.19

vertical velocity -

pitch rate 0.26

pitch angle 0.17

Longitudinal modes

Model data from: Sun et al (2007)

Does the control system match the modes of motion?

Variable Gain to stabilise

forward velocity 0.19

vertical velocity -

pitch rate 0.26

pitch angle 0.17

Longitudinal modes

Variable Gain to stabilise

side velocity ∞roll rate ∞yaw rate -

roll angle 1.05

Lateral modes

Model data from: Zhang & Sun (2010)

Insect modes of motion

Sensory input

Force output

Flight control system

Black box approach

Windsor, Bomphrey and Taylor (2013)

Windsor, Bomphrey and Taylor (2013)Animation and Movie courtesy of Shane Windsor

Stimulus

Response

Phase

Magnitude =Stimulus

Response

roll

pitch

yaw

Frequency response

Position or rate response?

Windsor, Bomphrey and Taylor (2013)

AxisWhat is required to stabilise flight?

Measured response

Roll Roll angle Roll angle

PitchPitch anglePitch rate

Forward velocity

Pitch anglePitch rate

Yaw Passively stableYaw angleYaw rate

Axis comparison

Windsor, Bomphrey and Taylor (2013)

movie: T. Nakata

Dr Toshiyuki Nakata (Postdoc)

Dr Nathan Phillips (Postdoc)

Dr Jorn Cheney (Postdoc)

Ms Florence Albert-Davie (PhD student)

Ms Hannah Safi (PhD student)

Mr Fergus McCorkell (Dphil student)

ALUMNI

Dr Per Henningsson