Ultra Endurance + Long Range Identity Crisis

By Austin Blair on Nov 14, 2019

25  2,070  6

UPDATE: This aircraft has now successfully flown a trip of 20.18 miles and back, and a maximum flight time of 1:22:34!
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This build started out as a way for me to get in the air quickly, and most importantly, on a budget. That was, of course, until the desire to push the envelope took over. If there's one thing I want to emphasize the most, it's the potential this airframe possesses right out of the box. For only $90, you get a well designed platform to do with whatever you please. While I've seen countless builds go well over 100mph, my goals quickly became endurance and long range, two things this wing was destined to do well. Be sure to visit my up-to-date logbook of this aircraft's adventures here!
https://rotorbuilds.com/build/20747#
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Starting with a solid set of servos from the PNP version of the Recruit, my focus quickly shifted to gains in efficiency with the powertrain. With a background in custom Li-Ion batteries, I know just how beneficial they can be in a build like this, so I quickly ordered the highest density 18650 cells I could find. Due to the fact the single motor setup draws such little current (16A max in most cases), I knew I could get away with a tightly packed cell. For this, I turned to the Imren 3500mAh 30A 18650. I know what you're thinking, surely the 30A max discharge rate is overkill, especially considering I just said the wing pulls around half the current. This cell gives us the option to eventually change our configuration to a 3S or 4S 2P setup in the future, or load up our prop without worry of overheating. Even with such a high overhead, the cabin temperature regularly reaches 90F with front ventilation closed, so results may vary in warmer climates.

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As for our drivetrain, I've been a huge fan of the Xing series of motors since their debut, simply for the elegance in their rounded bell design. Looks aren't the only thing the Xing lineup has going for it, however, as this creates an incredibly lightweight and durable motor, perfect for not only freestyle miniquads, but also a long range setup where every gram needs to go towards usable kinetic energy. The quality of bearing in this motor is exceptional, and I have zero concerns of lost efficiency from bearing drag. Less consideration can be put into the ESC, as the industry's technology has made virtually any modern ESC highly efficient. With this in mind, I picked the FlyWoo 45A Slim ESC, for both its lightweight, small form factor, as well as the capability to run BLHeli_32. Having telemetry from the ESC in regards to motor RPM isn't crucial for filtering in a plane like it is in a multirotor, but it allows us to compare propeller loads and current draw in the real world.

Finally, for our flight controller, I went with the tried and true Matek F405-Wing, simply for its elegant three-plate mounting system, along with the future expandability for up to six UARTs, giving me the option to add more peripherals in the future, such as an airspeed sensor. The F405 is running iNav version 2.2.3.
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Wire management on a wing is typically an art rather than a science, but I'd say this setup came out decently clean

This thing flies incredibly well for its relatively diminutive stature. Wings of this class typically feel darty, nervous, and add a level of complexity to getting off the ground. With the AR Wing, it's as easy as giving it 75% throttle or more, then giving it a light toss into the air. There's no worry of surprises once it leaves your hand, tracking true as an arrow. It's the same story at altitude, to the point I flew an entire hour in manual mode with little more than pitch correction when I entered thermals, another trick up the AR's sleeve. Throughout my one hour endurance run, I routinely encountered thermals that I was able to gain upwards of 50 feet with, further increasing my overall efficiency, as well as cementing the fact the AR wing is a truly incredible platform.
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Photos

Discussion

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beeb   Dec 24, 2019  

Very nice build! I also made an AR Wing and I'm now considering Li-ion options. From quads I'm used to using VTC6 and LG HG2 cells, but looking at the ones you chose, I thought "OMG so many mAh with such high current, amazing!". Then I went for my trusty source of Li-ion tests and my worries came true. You cannot expect to draw 30A from these, let alone 20A. They are relatively stable at 15A but then you're anyway not getting more juice out of them compared to a VTC6 for example (and the Imren are probably heavier). Imren: https://lygte-info.dk/review/batteries2012/Imren%20IMR18650%203500mAh%20%28Green%29%20UK.html LG: https://lygte-info.dk/review/batteries2012/LG%2018650%20HG2%203000mAh%20(Brown)%20UK.html VTC6: https://lygte-info.dk/review/batteries2012/Sony%20US18650VTC6%203000mAh%20%28Green%29%20UK.html

Austin Blair   Dec 24, 2019 

Ooh thank you for those links! I agree, they start to get warm when pulled at 8-10 amps, but the plane only cruises around 2.5. I'm considering making a 6S pack, and might go back to VTC6, but I haven't decided yet. The Imrens are still a pretty decent battery.

joshielevy   Nov 15, 2019  

Very nice detailed log!

Austin Blair   Nov 16, 2019 

Thank you! The extra 5 minutes of logging after each flight pays off when you want to track marginal gains in different equipment.

Austin Blair   Nov 14, 2019  

I've uploaded my DVR from an 8.01 mile flight here:

jseaber   Nov 15, 2019 

This was an epic LR flight!

Crossfire failsafed as Smokey turned around 8 miles out (only set to 100mW). Return to Home kicked in as expected. The wing cruised back and regained a Crossfire link, but there was a moment of concern when iNav would not release FS/RTH. Smokey managed to regain manual control while the wing circled the field.

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