FPV micro racer – my preferred recipe

Build #1 Micro FPV racer – Frame combo available here:

I initially constructed this setup to see how well a micro brushed quad could stack up against brushless quads in a small figure eight time trial as proposed here: https://racingmultirotors.wordpress.com/ so it had to be light and fast.
So far initial test times are very encouraging but I’m waiting for warmer months to really see what’s possible.  It would be great to see some others try this build and help push the limits.

Updated photo with Hyperion cameras installed:
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This build is constructed using the following:

Efficiency 120 FPV wide arm frame
Wide arm version is suggested for recreational racing, and practice when using 8.5mm motors.  The standard (non wide arm) version is ideal for maximum performance and with lighter builds using smaller motors but is not quite as durable.

4” Roll Bar
This is not necessarily required and does add approximately 1 gram to the build, however it is much appreciated if any crashing is expected and greatly aids in camera positioning/mounting.  The camera/transmitter combo is angled back at approximately 30 degrees and secured to the roll bar with a bit of hot glue at each corner which offers antenna protection too.  Loom bands can also work well to secure the antenna to the roll bar as pictured.

8.5mm wide arm motor mounts
8.5mm motors are preferred for maximum thrust to weight when carrying FPV gear.  I suggest getting at least 1-2 extra mounts if a lot of crashing is expected, or select the HD protected wide arm mounts if you don’t mind the slight extra weight.

CL-0820-15 motors
These allow use of larger CG022 or Parrot propellers which tend to grip the air a bit better for tight 180 degree turns. 
Cl-0820-17 motors and Hubsan (or similar sized) propellers are also another option worth considering. I have yet to test this but expect they will slip through the air a bit more though possibly faster.  A dab of hot glue is also applied to the bottom of each motor where the motors exit to provide some strain relief in that area.

Quanum 32 flight controller
This is currently my preferred ready available flight controller, however just about any can be used.  Some considerations should be made to ensure the camera is not positioned directly on top of any critical components.  For this particular build the camera is positioned against the top of the USB connector and cushioned with a layer of  foam tape.  The flight controller is also cushioned and secured with a layer of adhesive foam tape.  A rubber band is also wrapped around the flight controller to help secure it to the frame and is also used to help secure a battery to the underside of the frame.

VA1100 camera transmitter combo (or FX797T, Hyperion, Cricket…….. 25mw camera transmitter combos)
This was selected mainly for its light weight, although image quality and light sensitivity leave some to be desired (newer models seem to be better).  Since this build was aimed at small scale figure 8 racing, using a lighter 25mW transmitter was determined ideal for performance with acceptable quality.  A micro 1.25mm JST plug set can also used to allow removal of the camera and roll bar for a simple LOS/acro configuration.  This is soldered directly to the +/- battery pads on the FC to ensure power from the battery to the FC is not compromised.  More recent 25mW camera combos (than VA1100) seem to improve the video quality without compromising weight.

CG022 or Gemfan 65mm propellers
For fast 180 degree turns larger propellers tend to grip the air better.  I generally interchange between the CG022 and Gemfan 65mm (similar to Parrot) props.  Gemfan 65mm seem ideal for fastest runs however with lots of high throttle input these can really heat motors up.   CG022 are used to increase motor life and provide slightly longer flights when absolute peak performance is not needed.

300-600mAh batteries
For the absolute lightest weight 300mAh 45C+ Nano-tech (or similar) batteries can be used, however flight times likely be just long enough to complete the figure eight time trial initially referenced (<1 minute).   For practice and general fast flying, the 480mAh My-lipo (can be tough to get) offered by the Micro motor warehouse and the 600mAh 35C+ Nano tech/Graphene (or similar) seem to be good options.  750mAh and larger may also be applicable however I personally found using 750mAh batteries limited performance too much to justify any potential flight time increase.

Below is a close up picture showing a Hyperion mini camera transmitter combo secured with loom bands.  The 120mm frame size allows use of 65mm propellers with the front 2 props visible just along the bottom edge of the camera view with the camera angled as shown. IMG_1865

 

Here is an image of a well used build showing how the case of a Cricket camera transmitter combo was secured to a roll bar using hot glue.  This particular build is well used and after many crashes, a high speed impact with a chain-link fence finally broke the roll bar.  The camera transmitter combo remains intact however and even broken the roll bar still adds a fair bit of protection but will ideally be replaced.

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