Actively-stabilised rocketry

Introduction

As part of the final year of my undergraduate engineering degree at Cambridge in the academic year 2006-2007, I am undertaking a project to build an actively-stabilised model rocket. The vehicle I am working on is "Kestrel", a lunar-lander-style rocket designed for very low-altitude flights (around 1.5m/5ft) on long-burning motors with cold gas thrusters for attitude control.

Kestrel's airframe

My project is supervised by Dr Hugh Hunt from Cambridge University Engineering Department and Professor Chris Bishop from Microsoft Research. I am indebted to them and to many others for their advice and assistance during this project.

I could not have undertaken the project without the generosity of Microsoft Research in sponsoring me. I am also very grateful to Tyreinflators.co.uk for donating the gas cartridges I am using.

Flights

Kestrel's maiden flight took place on Sunday 6 May 2007 at the East Anglia Rocketry Society's "Big EARS" launch event at their Elsworth launch site. After a weekend of tweaking in a field near Elsworth, I launched the Kestrel actively-stabilised rocket on an Estes E9-P. Unfortunately the control system appeared to have little effect (I suspect it may not have engaged) and the rocket flipped over and crashed, damaging the electronics. However, my determination to make it work is still intact and hopefully it will fly again soon! See the full launch report or a video of the flight (6.0Mb AVI, requires the Xvid codec; originally filmed by Ed Moore, deshaken by VirtualDub and Deshaker).

More information about flights, successful or unsuccessful (!), will appear here in due course.

Technical information

Motors: to date, one Estes E9-P (3s burn); potentially in future an Aerotech G12-RCT (9s burn) - the airframe currently has a 32mm motor mount.
Structure: primarily 1mm aluminium sheet (cut to shape using an Omax abrasivejet cutter) and fibreglass and carbon fibre kite spars (supplied by Airborn Kites and Active Toys).
Attitude control system: 4 cold gas (carbon dioxide) thrusters, each with a nominal thrust of 1N on a 200mm moment arm, giving control over pitch and yaw; each thruster is controlled by a Festo MHE2 solenoid valve (supplied by Cambridgeshire Hydraulics and Pneumatics Ltd).
Compressed gas supply: carbon dioxide from a 16g carbon dioxide cylinder for bicycle tyre inflation (donated by Tyreinflators.co.uk). After an adaptor and pressure regulator, standard 6mm push-fit pneumatic fittings are used to connect the supply to the valves and thrusters.
Onboard electronics: the processor is an NXP LPC2138 on a development board supplied by Embedded Artists; rotation rates around the pitch and yaw axes are measured by two Analog Devices ADIS16250 solid-state rate gyros.

Documents

Technical Milestone Report (0.3Mb PDF)
Michaelmas term design presentation (7.5Mb PDF)
Final project report (6.9Mb PDF) - note that further work has been carried out after this was submitted
Easter term final project presentation (4.9Mb PDF) - ditto

Other actively-stabilised rocketry projects

Gyroc: a gimballed-engine rocket built by Jim Macfarlane and Michael Procter in the UK from 1996 - present, described in some detail on the following pages: ukrocketman.com, Michael Procter's website
Casimiro: another gimballed-engine rocket built by Cristiano Casonati in Italy, described on his website (in Italian - translated by Google)

If you know of any other such projects, I would be very interested to hear about them - please let me know!