HK S500: How to make it even better with a few modifications

Usually I build copter frames myself but for a copter to strap to my backpack and to carry around where ever I go I was looking for a cheap solution that does not ruin my day when crashed.

Browsing the web I found the S500 frame on the HobbyKing page. For a mere 20 bucks you get a solid frame with AWESOME arms, so it seemed to be a good basis for my project!
One thing a lot of people disliked is the landing gear because it tends to break. I did not like it in general because it is pretty high and not foldable, making it very awkward to strap the S500 to a backpack when being outdoors.

The Copter was designed to mount the Gimbal underneath it- one reason for the high landing gear, sure.

From my point of view- especially with the upswept arms- there are much better ways to mount a Gimbal. The Tbs Discovery Pro for example has the Gimbal mounted in front of the fame. One big disadvantage besides the price are the arms of the Discovery- the S500 arms are much stiffer which is a big plus.  The Tbs is more of a “dead cat” style copter, but with the S500 the arms also should not be in view when the Gimbal is positioned properly.

For the copter of my hiking dreams I removed the S500´s landing gear and the battery holders because I wanted the flattest side face possible to be able to strap it to my backpack even when climbing or skiing. To achieve this I had to design a new Gimbal holder, new battery mounts and detachable landing legs- one could live without legs but I like having them with me to be able to start on grass and other uneven surfaces.

One thing I REALLY dislike is to ruin GoPros on rough landings. Sure- a Layer Lens helps but more protection is better. Furthermore the usual strap mount for the GoPro on most Gimbals is far from perfect- to say the least. For this reason I mounted a Quanum Super-Light Alloy Case directly to the Gimbal (2 x M2 screws, Epoxy). I had to trim the Gimbal a little to find the perfect balancing but that was rather easy. Now every time I put the GoPro in the holder it is well protected and balancing is spot on. Good stuff!
Without the landing gear mounted and no battery the silhouette of the copter is really flat. I can even leave he props mounted when I strap it to my backpack- perfect.

As a flight controller I used a NAZA light with V2 firmware which performs well. It is controlled with a Tbs Crossfire Micro, VTX is 2.4GHz. I also installed a MinNaza OSD to be informed about the crafts status at any time.

It is extremely reliable, flies very stable, has a really long range and gives me super-smooth video- I am pretty happy with the outcome. Even with unbalanced props (of good quality…) I have no jello whatsoever- even in the brightest sunlight! (your milage may vary- as always)
Meanwhile HobbyKing sells the Dead Cat Pro which also looks promising (same arms, even a “Dead Cat” layout) but it is optimized for a Mobius and also needs to be modified to be strapped to a backpack.

The 3D printed parts I designed for my mod are available for download on Thingiverse:

-          Gimbal Holder: thing:1660421
-          Battery Holder: thing:1660418
-          Landing Gear: thing:1660415

I printed these in ABS. Landing gear and battery holder clip on the rails, the Gimbal holder is press-fit but you also might use a drop of glue depending on your tolerances.
The other parts I used for my build are (most of them were bought at HobbyKing or on Ebay):

-          Frame: S500
-          Motors:  Multistar Elite 2216 920KV
-          Gimbal: Cheap 2 Axis GoPro Gimbal with Alex Mos Controller
-          GoPro Cage: Quanum Super-Light Alloy Case
-          ESCs: F30A with BLHeli
-          Propeller: Graupner C-PROP 10“x4“
-          Flight Controller: NAZA lite
-          FPV Camera: FatShark Pilot Cam 700 CCD
-          VTX: 2.4GHz
-          RX: TBS CROSSFIRE micro receiver
-          Battery: 4S 5000mAh












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