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Studio Session-075.jpg

Top Mount Flaco

I was joking around with Chris 'Patient 0' the other day, and I remarked that if side mount frames were truly designed from the ground up, they'd look like a Blackout turned 90 degrees. Don't get me wrong, I did the same with one of the early iterations of Hedwig, but mounting a battery laterally on a longitudinal frame just means you're incurring extra drag. Of course, no one would actually make a sideways Blackout, 'cause it's just too unconventional, even though it would make more sense.

Chris said he wouldn't mind it, and if I made it he'd fly it. I told him I was just kidding around and had no intention of making a sideways Blackout, but he kept asking me why I wouldn't and he eventually got me thinking.

It's hard to go back to wide arms after flying Flaco, so that rules out a monoplate. The Flaco arm system is proven, so I'd start with that as a base. I drew up wider mid and top plates, and printed them up in nylon to mock it up. I decided to go with the stretch X arms to get the props away from the battery leads (that, and it flies nice).


That seemed decent, except for the fact that my camera and antenna mounts would hook around the standoffs, and now the standoffs are really far apart. I could put standoffs on those closer set screws as well, but it seems silly to have 8 standoffs on such a small plate.

Then I thought I could use the existing plate for the middle, and just have a wider top plate that overhangs the standoffs on the sides. A few minutes later it finally dawned on me that I could just use the existing plate on all three layers and let the battery overhang a bit.

We're done! Miller Time!

We're done! Miller Time!

Now for a cam mount. I'd made a minimal strap for the Runcam Micro a while ago, but some people found that it didn't protect the camera enough. So this time I drew up a semi-enclosed mount with 30-60 degrees of tile. 

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This was gradually streamlined 'til I got to here:

I'd originally drawn the pillars around the standoffs at 20mm, the full height of the standoffs I was intending to use, but @jfk.fpv said he could build his as low as 15mm so I dropped them down to 15. Then I had to make versions for 2.1 and 2.3 lenses, since their dimensions are pretty different.

My first shot at the butt looked like this, which wasn't terrible.

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But it didn't quite jibe with the nose aesthetically.

One's convex, one's concave. No bueno.

One's convex, one's concave. No bueno.

I eventually wound up with this, which works with the cam mount better, and also blends with the carbon plates.

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Time to Build

I took apart an already built Stretch Flaco to make the conversion. I figured that I could turn the Aikon 4in1 90 degrees and run a super short battery lead, which would be so tight that it could never get cut by props without having to strap it down (chopped leads is one of the biggest drawbacks of top mount frames) . I swapped out the Radiance for my new favorite Fortini + Stealth combo, which gave me full OSD control of pids, vtx, and camera settings. Things are super tight with just 20mm of headroom, so ideally I'd use the tiny R-XSR. Sadly I couldn't find one in stock anywhere so I went ahead and put an XSR in there. 

This created a 'ten pounds of crap in a five pound bag' situation, with things so smushed that the Fortini was no longer soft mounted and isolated from vibes. The quad hovered with a yaw hitch if things were squished in too tight against the gyro.

With the Aikon rotated 90 degrees the motor wires entered the stack at the front and back instead of the sides. so it was a good thing I made the two pods just 15mm high. Good dumb luck there.

The maiden went well, 'til a ghost branch reached out and took me down, ripping out a motor wire in the process. I didn't fully open it up while it flew, but even in that short time I could feel how it was less prone to propwash shakes in hairpins. This kinda makes sense – a perfectly balanced quad isn't going to pendulum out in a direction change, so it's not going to initiate an angle change that the FC has to combat.

I fixed it up and the yaw hitch reappeared and stayed. I must've damaged the board by smashing the parts down too hard. I replaced the board, gave myself a few mm extra headroom with some tpu spacers, and now it flew just fine, but with flickering video. Swapping out various parts failed to fix the flicker, until it dawned on me that it was a loose XT60. Four days of swapping parts when the problem required a two second fix.


I flew it on my usual practice course and beat my best time by a half second. I wish I could understand why, but 50 degrees on this frame feels calm and normal, while 50 degrees on Arkangel feels insane, even though lap times are very close. Maybe the lack of propwash shakes contributes to a sense of calmness. 

And here's Control.fpv testing mine. You can see him slowly getting acclimated, as the lack of that pendulum throw leaves him short on a couple of the turns early on. He slows down, gets the feel of it, then rips a couple of fast laps at the end.

You can pick one up here, or you can convert an existing Flaco with just one extra middle plate and printing your own parts, here.