Outfitting the Gaui 500X for FPV and Aerial Photography

Unafraid to Crash

Several months ago I picked up a Gaui 500X Quad Flyer kit.  I wanted an inexpensive platform for learning FPV (first person view) flying and light aerial photography.  I have several larger multicopters for professional photography.  But I wanted a small practice aircraft that would be cheap to fix.  I didn’t want to be afraid to crash it, while improving my piloting skills.  This article takes a look at the Gaui 500X for this purpose.

Gaui 500X First Impressions

When I first opened the box, I was impressed with the engineering quality of the whole package.  For example, the ESC’s are amazingly tiny.  They fit inside the quad’s arms, so both wires and ESC’s are hidden.   Very nice.  The wiring harness is an extremely small and simple design, constructed from bullet connectors soldered together.  Reliable.  There’s a very light weight blade guard to prevent blade strikes should the copter bump into something.  The arms of the quad are foldable, so you can pack the whole thing in a small canvas bag (included in some kits).  And there’s an optional lighting kit with LED’s for each motor mount.  This makes day flying easier and night flying possible.

Good Motors, Good Electronics

In case you’re wondering whether there might be overheating problems with internally mounted ESC’s, the motors and ESC’s run warm, but never hot.  Even with heavy loads (over 1600 grams but under the 2200 gram limit), I’ve never had overheating (unlike my larger multicopters).    The Scorpion motors are small, but efficient and ample for the quad plus a small camera.

Gaui 500X Motors and Electronics in an AGL Hobbies frame

Gaui 500X Motors and Electronics in an AGL Hobbies frame

 A Battle Hardened Frame

Though I like the Gaui frame, which looks quite sleek, I wanted a frame that could take a real beating.  So, I put the Gaui electronics and motors in a “Rusty Rev. 7” frame (pictured above).   This frame was from AGLHobbies.  The Rev 7 frame has been discontinued, but the newer models are both better and cheaper.  I highly recommend these frames as a rare combination of low price and high quality.  My Rev. 7 once crashed after the quad lost power from 15 feet above my driveway.  It hit hard.  But the damage was only two bent arms (Align Trex 450 tail booms), two broken props, and a bent motor shaft.  Under $25 in repair costs for such a hard fall.  None of Rusty’s G-10 fiberglass or delrin parts broke, or even cracked.  Amazing.


Above is a picture of the Gaui motors, electronics and wiring harness mounted in the Rev. 7 frame.

It took under two hours to assemble the Gaui parts in the Rev. 7 frame.   The complete quad copter, without the battery and without the camera, weighs a total of 988 grams.  This is well under the 2200 gram all-up limit suggested by Gaui.  It leaves about 1200 grams for battery, camera and camera mount (if used).  The GoPro camera is about 200 grams.  Batteries range quite a bit, but I use a 3S, 5000 mah, 30C battery which weighs about 400 grams.  It provides roughly 12 minutes of flight time with the camera mounted.  With an all-up weight of 1600 grams, it’s still 600 grams under Gaui’s stated lifting capacity.

Some Minor Issues

Nothing is perfect.  Here are a few minor issues I found with the Gaui hardware.

First, the prop mount is a threaded brass bushing, which is very thin. If you over tighten a propeller, the bushing will fracture.  It’s unusable when this happens.  As a quick fix, an Eflite part happens to fit the Gaui motor.  It’s part “EFLM1922 3mm Prop Adapter with Collet.”  Most hobby stores stock the Eflite part, though they may not stock the Gaui part.


Broken Gaui 500X Prop Mount

Broken Gaui 500X Prop Mount



However, it’s easy to avoid snapping the prop mount.  When you tighten the propeller nut, hold the motor casing (it’s an outrunner) with your index finger and thumb ONLY.  Don’t grab the motor with your whole hand.  As you tighten the prop nut with a wrench, no matter how hard you squeeze, at some point the motor casing will slip between your fingers.  This prevents over tightening.   You may not think you’ve tightened the prop nut enough. But the prop mount grips the propeller more snugly than you may think.  I’ve never had one loosen using this method.  Nor have I broken any more prop mounts.

Safe Tightening of Prop Mount

Safe Tightening of Prop Mount

The second minor issue is with the GU-344 Stabilizer.  This is the electronic box that contains the gyros, accelerometers and computer.  Generally, it works quite well once adjusted properly.  However, there is a trim pot on the unit that allows you to adjust the gyro gain with a screwdriver.  If the gain is too low, the quad will wobble like a drunken sailor.  If the gain is too high, the quad will oscillate a bit.  Getting the right spot is tricky because very small movements of the pot can make surprisingly large changes in gain.  Homing in on the best spot is difficult.  Don’t panic or give up.  You’ll get it with a bit of trial and error.  It took me at least 6 tries.

The last issue I noticed was with one of the 4 motors that came with my quad.  Because I was planning to shoot some video, I checked for motor vibrations with an iPhone app called “Seismometer.”  I’d strap the iPhone to an arm near the motor in question, turn on Seismometer and power up the motor.  Seismometer graphs the vibration.  It’s not as good as a vibration meter, but it does give you a rough idea of how smoothly your motors (and props) are spinning.  Using this method you can see which motors are well balanced and which are not. 3 of my Scorpion motors were well balanced and one was way out of balance.  I replaced this motor with one that was better balanced.

The Bottom Line

It’s been about 4 months since I built the Gaui 500 with the custom frame.  During that time, the hardware and electronics have performed flawlessly.  There have been crashes, of course.  But the damage is usually no more than a broken prop.  I’ve flown with both 3s and 4s batteries.  I’ve been amazed at how much weight the motors and ESC’s can lift (tried up to the 2200 gram limit) without signs of over heating.

So, if you’re looking for a small multicopter for FPV or photography with a light camera, the GAUI 500 is well worth considering.

Here’s a brief video showing how stable the Gaui is in a hover.

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