Andrew Rabbitt
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  • Melbourne, Victoria
  • Australia
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Andrew Rabbitt's Discussions

Logging airspeed on 2.74 onwards...?

Started this discussion. Last reply by Andrew Rabbitt Feb 6, 2014. 2 Replies

Does anyone know which parameter group I can find airspeed to log (passively). I have looked in CTUN and NTUN but neither appear to have this listed. Any hints and tips here...?

APM in a 250

Started this discussion. Last reply by Rob_Lefebvre Jan 20, 2014. 8 Replies

The crazy man in me is trying to stuff an APM into a cheapie HK250GT as a method to waste an inordinate amount of time. (and likely also money) It is a great lesson in weight reduction and…Continue

Arduino/Ardupilot IDE "hangs" whilst attempting to complie

Started this discussion. Last reply by Andrew Rabbitt Aug 9, 2013. 1 Reply

I'm trying to compile a (very) subtly modified version of Arduplane 2.74b using the IDE downloaded from the Arduplane website (1.0.3) but it hangs when I try to compile.  Actually, it doesn't hang…Continue

Mapping servo neutral and end points...?

Started this discussion. Last reply by SKYBORNE May 6. 6 Replies

Does anyone know any way of mapping the servo mid and end points that APM uses?I have modified elevons on my Skyfun which, unfortunately, have a limited down travel.  If the elevon servo forces it…Continue

 

Andrew Rabbitt's Page

Latest Activity

John Mitchell Smith commented on Andrew Rabbitt's blog post Climb-Glide: Improving the range of fixed-wing, electric UAVs
"Great article and info Andrew. Thanks for posting this."
Friday
Andrew Rabbitt commented on Andrew Rabbitt's blog post Climb-Glide: Improving the range of fixed-wing, electric UAVs
"@JB.  Good luck with testing the concept and good luck with the OBC!  Funny you couldn't get on the DIYD.  I've been blocked on my smartphone until yesterday when using a Telstra GSM, but not on a WiFi connection.…"
Wednesday
JB commented on Andrew Rabbitt's blog post Climb-Glide: Improving the range of fixed-wing, electric UAVs
"Hi Andrew thanks for the excellent post. For some reason DIYD hasn't been accessible for me over the last few days (this happens every month without fail) so I only found this post now and will need some time to digest. It looks good though,…"
Wednesday
Swift commented on Andrew Rabbitt's blog post Climb-Glide: Improving the range of fixed-wing, electric UAVs
"thank you for posting Andrew, and very well published, wish I could have your talent."
Wednesday
Andrew Rabbitt commented on Chris Anderson's blog post Delft VTOL project uses helicopter-style main rotor for effeciency
"It'd be interesting to compare performance with a conventional helicopter which is about equivalent in complexity."
Wednesday
Andrew Rabbitt commented on Andrew Rabbitt's blog post Climb-Glide: Improving the range of fixed-wing, electric UAVs
"I should correct myself.  Thrust/power doesn't degrade linearly with speed because it's really a 1/n function"
Sep 19
Andrew Rabbitt commented on Andrew Rabbitt's blog post Climb-Glide: Improving the range of fixed-wing, electric UAVs
"Gary, what's confusing the issue is operating the propeller at zero advance ratio (static).  If you look at the thrust and power coefficients of propellers, you'll see they don't change much with speed under static thrust…"
Sep 19
Gary McCray commented on Andrew Rabbitt's blog post Climb-Glide: Improving the range of fixed-wing, electric UAVs
"Hi Andrew, Although the KDE chart is represented as static thrust, if the prop pitch and motor RPM are adjusted for a given (appropriate) velocity, the efficiency curves for the motor stay pretty much the same. I do understand that under ideal or…"
Sep 19
Andrew Rabbitt commented on Andrew Rabbitt's blog post Climb-Glide: Improving the range of fixed-wing, electric UAVs
"@Gary, regarding your point of integrating this into an autopilot, I think it has some merit.  Actually some of the reasons for my interest here is an attempt to generate a full physical model-based autopilot system.  It's been on the…"
Sep 19
Andrew Rabbitt commented on Andrew Rabbitt's blog post Climb-Glide: Improving the range of fixed-wing, electric UAVs
"@David L For correcting tail and headwinds, the maximum range speed point moves faster for headwinds and slower for tail winds.  You can calculate what this value is by offsetting the speed-axis crossing of the tangent line by the head or…"
Sep 19
Andrew Rabbitt commented on Andrew Rabbitt's blog post Climb-Glide: Improving the range of fixed-wing, electric UAVs
"Hi Gary, Thanks for engaging with me on this. I see the point you're making, but I think I haven't described my ideas as well as I might, so let me have another go.  Firstly your example data set set you give is only dealing with…"
Sep 19
GliderUAV commented on Andrew Rabbitt's blog post Climb-Glide: Improving the range of fixed-wing, electric UAVs
"Hi Andrew, I agree, there will be for efficiency gained for reasonable e-gliders. I've attempted to calculate this with MotoCalc, which can calculate motor at any throttle setting, as well as aircraft size and profile. Also, i tried…"
Sep 19
Gary McCray commented on Andrew Rabbitt's blog post Climb-Glide: Improving the range of fixed-wing, electric UAVs
"Hi Andrew, You said: " If you plot efficiency curves you will find motors become more efficient as you increase voltage." In fact for the motors we use, that curve goes up, then down. Electric motor efficiency is not that simple,…"
Sep 19
David L. commented on Andrew Rabbitt's blog post Climb-Glide: Improving the range of fixed-wing, electric UAVs
"Where the head wind and tail wind factor in the graph?  I usually take advantages of mother nature to get me extra climb-glide efficiency on my tiny plane.  Its works and flew more than hours on tiny pack. Small prop and lighter prop helps…"
Sep 19
Chung Sing L. commented on Andrew Rabbitt's blog post Climb-Glide: Improving the range of fixed-wing, electric UAVs
"Andrew, Would you be kind enough to share the spreadsheet? I am interested in looking at some of your calculations for the graphs. Cheers, Chung"
Sep 19
Andrew Rabbitt commented on Andrew Rabbitt's blog post Climb-Glide: Improving the range of fixed-wing, electric UAVs
"Gary, my point regarding motor efficiency was that if peak efficiency is at 30% of rated power, the only way you have to achieve this 30% is by reducing terminal voltage (or voltage * PWM ratio).  If you plot efficiency curves you will find…"
Sep 19

Profile Information

About Me:
Mechanical Engineer with more than a decade in electronic engine control development and application in the OEM sphere. I am a lapsed PPL(A) and currently an experimental aircraft builder (Van's RV-8). UAV's are a fascinating diversion from rivetting...
Please tell us a bit about your UAV interest
Inspired by press articles earlier this year on near-space ballooning, I would like to one day send a UAV glider aloft for a positionable return to land. I'm sure others have similar ideas.
Hometown:
Melbourne, Australia (sometimes)

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Andrew Rabbitt's Blog

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

Posted on September 18, 2016 at 12:56am 22 Comments

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…

Continue

Exploring the secrets of flying wing design with CFD.

Posted on July 28, 2015 at 9:36pm 44 Comments

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…

Continue

Wing lift distribution presentation

Posted on March 27, 2015 at 12:50am 11 Comments

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...?

Digital flight control research from the '80s

Posted on March 2, 2015 at 4:25am 11 Comments

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!

Comment Wall (4 comments)

At 6:15am on February 11, 2012, Paul Marsh said…

Oops.  Wrong URL in my PM to you.  Try this:

http://www.poweredmodelairplanes.com/outline.wrl

Paul

At 6:32am on June 17, 2013, Acorn said…

Andrew - Thank you for commenting on my BLOG DIY Passive Gimbal.

How about whacking four free-spinning electric motors on it? One flanking each axis? Just so it is balanced. Would they cancel eachother out? Or would making them spin CW / CCW to each other be better?

At 5:57pm on November 20, 2013, Justin Martin said…

Hello Andrew! Thanks for the support, and offer. I will definitely keep you in mind if anything comes up. The Idea behind the albatross is open. By this I mean, it has specific goals and design elements, however in the long run I would truly like innovations to be customer based. For instance, If customers started laser cutting their own internal storage shelves/formers, and/or other mods, such as a dome/nose adapter.

If the Pro version every comes to be, I will definitely be needing some specific arts, such as retaining clamps and rings for easy quick-release style components.

At 8:01am on April 23, 2015, Paul Meier said…

Hi Andrew

I have seen your pic of the qx 100 teardown. I want to teardown my qx 10 but before I do may I ask do you think it is possible to soldier a connection on where the shutter button is (on the flexible printed circuit) and then use pixhawk to trigger ?

Many thanks in advance,

Paul

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