Motor and Propeller Performance - Going beyond analytical results

A lot of thought goes into designing an efficient flying vehicle - if you've ever seen flaps on a passenger jet's wings, you'll have some idea of how many parts are involved in keeping a plane stable.

On a UAV, the same principles apply on a smaller scale. If the UAV encounters a gust of wind (turbulence") or needs to manoeuvre quickly, there needs to be stabilisation to prevent the disturbance from overwhelming the UAV. This is where practical testing for the motor/propeller combination is useful for obtaining actual flight characteristics so that the vehicle design can be improved.

We've made use of these characteristics during our R&D process and enlisted the help of our masters student, Zachary, to design and build this test rig. It features a gimbal-like mechanism to transmit the forces produced by the propeller and wind tunnel along the two axes, a variable force transducer location to utilise the full capacity of the load cell regardless of the electric motor/propeller combination used, and a universal motor mount to permit the mounting of various types and sizes of electric motors. The test rig also rotates on a stand to allow for testing of the propellers at multiple angles of attack (if mounted inside wind tunnel). 

On the primary axis is a subminiature load button load cell with a capacity of 111N (11kg) and this measures forces produced directly by the propeller. The secondary axis has a load cell with a capacity of 44.5N (4.5kg) and it measures the reactionary torque and lesser forces produced by drag of the test rig within the wind tunnel. The signals measured by the load cells are amplified on the data acquisition board and passed to the flight computer to be processed. 

The entire test rig was manufactured in-house from aluminium, along with 2 key shafts in steel for greater stiffness. The data acquisition board was also manufactured in-house. 

Results from this test rig can come from various combinations of fan speed and angles of attack, depending on the desired operating conditions.

  • Thrust is the primary data obtained from these tests - it directly measures how efficient this motor and propeller combination is.
  • Reactionary torque, as mentioned earlier, requires a secondary transducer in the perpendicular axis in order to measure it - this also means it can't be calculated analytically easily, which is why testing is crucial.
  • Impulse testing can also be performed - this determines how long it takes a given signal to reach a stable level, which affects the control systems design of the UAV. 

Are you designing your own UAV and would like real performance data for your chosen components? We can test motor/propeller combinations from anywhere - we can obtain the parts or if you prefer, send the components to us. To download a sample file of the data obtained from this testing, click here.

Announcing the Toadinator 8000

As the R&D lead for the Cerberus drone project, sometimes you get bogged down in detail and end up with a singular all-encompassing focus. This has its advantages, principally the delivery of robust and reliable systems, but one disadvantage is that creativity can be squashed. As a project progresses through its technical stages, innovative input (necessarily) diminishes as the prototype or product evolves.

This is why at Skyborne, we like to take a break from the long-cycle R&D process and just have a bit of fun. We like to give engineering interns intense, month-long challenges on machines that will push their design and practical prowess to the limits. Previously, we designed a 360 degree camera rover comprising of 6 Go-Pro cameras on a tripod, which was in turn mounted on a low speed skid-steer remote controlled base. We also established the viability of an ‘E-Roc’ Electronic Rocket, which looks at using a ducted fan in a long cylindrical vehicle.  

The Toadinator 8000 concept originally came from my girlfriend. She’s originally from North Queensland where toad infestations are out of control. She also hates toads with the fiery passion of a thousand suns. “Why can’t you make a machine to kill these things?” Well actually... maybe we could. Along came intern Josh, a very practical hands-on graduate that would be perfect for the role. With a very limited budget, Josh designed, manufactured, assembled and tested this little beast in just over a month. It has an FPV camera, a headlight, a pan-tilt turret and a Dettol pumping system so that you can sit on your camper chair and eliminate toads at will. For those of you unaware, Dettol kills toads in short order and has the same active ingredient as HopStop, which is sanctioned for toad elimination.

Of course we’ve got a few more mods to make. We need to make it waterproof, more crash-proof, cheaper for you and definitely with more lasers. You can’t have something with the suffix “inator” without a laser!  

Of course, if you’re interested in eventually buying the Toadinator for evening fun, check out toadinator.com and register your interest! We’ll let you know if we float a kickstarter campaign or if the unit becomes available for sale. Also check out and share our video. The more interest we have, the more likely we’ll be able to raise some development capital and push this onto the market. Remember to pay attention to the difference between a frog and a toad and don’t shoot irresponsibly! Other than that, happy hunting.   

So if you have a wacky invention idea, shoot it over! If you’re a well-accomplished engineering student who is looking for some hands-on experience, shoot us an email!

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As part of our overall business strategy, half of our efforts are devoted to aerial photography services for Real Estates, developers, hotels and similar industries. We need revenue coming through the door to stay alive, limit the early capital-raising equity giveaway, establish comprehensive networks and fund the R&D! When we first started the services side of the business, we copied the business models of our competition...a costly mistake.  If you’re copying someone else in almost every way, you are almost by definition securing yourself in last place. Let’s talk about the old business model and then the new one we have adopted at Skyborne Tech. 

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