My Open Source 3" HD Micro Quad Frame - The Kestrel

This new frame design has been brewing in my head for several months.  I knew I'd be ordering a CNC machine early this year, but I wasn't exactly certain of when.  I started the CAD work on this frame in January, and I didn't expect to have the ability to cut carbon fiber until at least March.  That's plenty of time, right?

Wrong.  I ordered the Shapeoko CNC earlier than I expected.  The machine arrived on January 31, and I had it assembled and ready for cutting before the weekend was over.  I'm not a patient person, so I was scrambling to get the CAD work done so I could cut a prototype.

I've never cut carbon fiber before.  In fact, I've never used a CNC router.  I have lots of 3D printing experience, and I've at least touched a laser cutter before, so at least it wasn't a completely new experience.

The Kestrel HD Micro Frame

The Kestrel is a smaller Acrobrat-like freestyle frame for HD FPV cameras with easily configurable arm geometry and individual, replaceable arms.  It allows for 3” builds under 200 grams, and (hopefully?!) 4” builds under 250 grams. The design is open source, and currently available on Thingiverse.

I want the Kestrel frame to be a good upgrade path from your existing 2.5” or 3” bind-n-fly micro. Pick up a Runcam Split Mini or Caddx Turtle, transplant the guts of your Leader 3, and start recording awesome HD freestyle footage.  That's what I did!

The Prototype

My prototype Kestrel is a compact 3" frame.  The arms positioned to put the props as close to each other and the fuselage as I'm willing to go, and the camera pod is far enough forward to keep the props out of view of the HD camera.

I only have DVR footage so far.  A Caddx Turtle arrived today, but it seems to be dead on arrival.  A replacement is probably about a week away!

My prototype is built using the guts of my inexpensive Full Speed Leader 3.  I've put it on the scale with dead Caddx Turtle.  Fully assembled, my prototype Kestrel weighs in at 125 grams.  All up with a 450 mAh 4S CNHL pack, it weighs in at 186 grams.  I think Caddx exaggerated the weight of their camera, because this is 3 or 4 grams tubbier than I expected!

Is the design complete?

No.  Not yet.  My first goal is to make things as light as I can manage without sacrificing too much durability.  The side plates and camera mount have already gone on a diet since their first test cut.  I think I may have gone too far, so I've beefed the top plate back up a bit.

The camera is farther forward than it needs to be.  I've done some work on the layout of the camera pod, but I'm waiting until I see how the Turtle fits before I relocate the camera.  I'm think it can go back at least 8mm, and I might move it upwards by a few mm as well.

You talk too much, Pat!

I do.  I'll try to finish this up in a paragraph or two.

I did some Betaflight tuning yesterday.  The 18 MPH winds didn't let me tune much, but I had a big nose dip on throttle input that I was able to mostly tune out.  The Kestrel is probably ready for its first HD freestyle runs.

I imagine the camera will be here Monday or Tuesday.  If the weather cooperates, I'll have some footage posted a day or two later.

Saturday is supposed to be a gorgeous day here in Plano, TX.  60 degrees and only 7 MPH winds.  It would have been perfect day to fly the Kestrel.  I guess I'll just have to fly my 5" instead!

I am Designing a Freestyle HD Micro Quad Frame at patshead.com

Micro HD Quadcopter Frame - The Kestrel  at Thingiverse

Boring Maiden Flight of the Kestrel DVR Footage at YouTube