Andrew Rabbitt's Blog (16)

Climb-Glide: Improving the range of fixed-wing, electric UAVs

A climb-glide routine can potentially yield a useful increase in range compared with the same airframe/propeller/motor combination operating straight-and-level at best range speed point or best endurance point respectively.

Let me explain briefly with graphs of the results how I have come to that conclusion, at least theoretically so far, hopefully…


Added by Andrew Rabbitt on September 18, 2016 at 12:56am — 21 Comments

Exploring the secrets of flying wing design with CFD.

The flying wing design I have been working on for some time now has been slowly evolving as I have learned more about aerodynamics and expanded my skill set with modelling tools of various forms.  I have recently completely re-surfaced my design with new aerofoil sections and better, more consistent surface transitions and have been experimentally analysing the results…


Added by Andrew Rabbitt on July 28, 2015 at 9:36pm — 44 Comments

Wing lift distribution presentation

A very interesting and thought provoking explanation of why the conventional wisdom of elliptical lift distribution needs rethinking.  Interesting for lovers of fixed-wing but also might be applicable for propellers and rotors...?

Added by Andrew Rabbitt on March 27, 2015 at 12:50am — 11 Comments

Digital flight control research from the '80s

I tripped over this on my suggested links and thought it might be of interest to the DIYD crowd.  Fascinating to see an original Macintosh being used as a ground station!

Added by Andrew Rabbitt on March 2, 2015 at 4:25am — 11 Comments

Telemetry Radio Range testing with home-made dipole antenna

On Sunday I spent the morning self-consciously traipsing around my brother's neighborhood with an apparently wierd collection of hand-held electronics and foam in the form or my APM, battery and a Hextronic 3DR knock-off 915MHz telemetry radio and Skyfun fin. We left a laptop on the top floor of the house running APM Planner with the base station radio connected directly to the USB port and using a standard "duck" monopole…


Added by Andrew Rabbitt on April 28, 2014 at 11:10pm — 14 Comments

1300kJ/kg Battery - from the Too-Good-to-be-True Newsdesk

This smartphone-sized pocket battery is being marketed for emergency starting of cars with flattery-battery-syndrome, but if the manufacturers specs are believable it would make a fantastic power pack for quads etc.  More than…


Added by Andrew Rabbitt on April 28, 2014 at 5:01pm — 15 Comments

Mercedes Benz vision systems research

I saw a feature about Mercedes-Benz collision avoidance vision systems research on the Telly here in Germany where I am at the moment. 


This particular project uses two cameras to create stereo vision.  Comparing the two images is used to detect pixels that represent motion that could be hazardous to the vehicles current path.



Added by Andrew Rabbitt on October 4, 2012 at 9:30am — 4 Comments

Mould Plug CNC Machining for HDwing4

Since the topic of CNC mills has raised its head here, I thought I'd share this with the DIYDrones community.

One of the things those who are considering this need to be aware of is that the toolpathing of complex shapes isn't a trivial exercise.  I would be interested to know if anyone has experience with any open-source surfacing toolpathing packages - please comment below! 

I am fortunate to have access to MasterCAM V9 - old-fashioned as it is - but…


Added by Andrew Rabbitt on May 24, 2012 at 10:03pm — 5 Comments

Introducing HDwing 4 - my motor-glider for high altitude balloon (HAB) launch

Some who have followed my blog posts will know that I have been working on my HDwing design series for a return-to-launch glider concept using ArduPilot Mega.  Everything I have revealed so far has been based on relatively conventional flying wing ideas. Till now...

This forward-swept flying wing concept was inspired by the work of Justin Ammon (EdgeRC / birdofprey) that I spotted on…


Added by Andrew Rabbitt on March 15, 2012 at 5:00pm — 21 Comments

Slow Flight with APM - mastering the PID on the edge of stall

One of the features of extreme high altitude flight is the high true airspeeds that are needed to generate the dynamic pressure required for airborne flight.  To minimise these extreme speeds for my high altitude glider project, I wanted to increase the flyable operation envelope closer to the airframe's stall speed, helping the reign-in the stratospheric true airspeeds!

As I was playing…


Added by Andrew Rabbitt on March 13, 2012 at 5:06am — 14 Comments

APM-guided High Altitude Glider Drop Simulation in X-plane

I've been working towards a realistic simulation of my high-altitude return-to-launch glider project in X-plane and this is the latest result which some here might find interesting.

The simulation is running with X-plane 9, APM-MP 1.1.36 (to keep the TAS into APM - more on that later) and a slightly modified version of ArduPlane 2.28.

To achieve the drop,…


Added by Andrew Rabbitt on March 1, 2012 at 1:30am — 15 Comments

Keeping APM Operational at 120000 feet - a first look

My ambition is to send APM aloft to the edge of space on the end of a balloon, and since it gets a little cold up there, I decided to take a look at what I would need to keep things running well.

NASA have kindly given the world a mathematical atmospheric model which shows that if I can meet the challenge at -56°C, I should be OK at any altitude.  Here is the temperature of the…


Added by Andrew Rabbitt on February 22, 2012 at 2:30am — 34 Comments

X-Plane Skyfun model - Work-in-progress...

Thought I'd share my progress so far on an X-plane model of the Skyfun.  I'm still struggling with PlaneMaker at the moment, so I've not flown it and have generated the data purely from scaling photographs knicked from t'interweb.

If you can help out with dimensions (metric please!) of things like the tail fins, chord lengths etc, that'd be great.

When it flies to some level of satisfaction, I'll release a version into the wild.…


Added by Andrew Rabbitt on October 18, 2011 at 5:43am — 10 Comments

APM flying HDwing at FL1000...

...well, in my dreams and in X-plane only so far.



It's been quite interesting trying to get a flying wing to fly at such high altitudes.  There are all manner of complicated instabilities to overcome.  So far, the biggest improvement was adding a motor and propellor, not as any form of thrust device, but as a gyroscopic stabiliser!



Added by Andrew Rabbitt on June 29, 2011 at 3:52am — 9 Comments

HDwing - my flying wing-borne HD-170 camera

My project to build a ballon-launched high-altitude automnomous glider as a step up from the normal styrofoam box HAB projects necessitates the development of an airframe.

Initially, I was intent on using the Skyfun platform but my calculations and other's experiences of it as an FPV platform suggests that it will be difficult to keep the centre-of-gravity in a useable location, especially if I remove the motor to turn it into a glider...

When I spotted the clever…


Added by Andrew Rabbitt on May 7, 2011 at 5:30am — 7 Comments

The Drift HD-170 POV camera as an on-board HD video camera?

As part of my plans to make a balloon-launched, return-to-launch UAV glider, I was looking out for a HD video camera that I could use in a typical fuselage installation.  I chose to invest my hard-earned into the Drift HD170 mostly because I figured the rotating lens meant that it was probably separate from the main processor board.  Only purchase and disassembly would…


Added by Andrew Rabbitt on March 12, 2011 at 12:00pm — 19 Comments

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