The Shrieker came about 'cause the boys wanted something for winter indoor flying. But in typical FPV Addiction fashion, we ended up with something a bit too powerful. It's fine for flying around a gym, but I wouldn't fly it in the tight quarters of my apartment – it's too fast, I don't want to whack things with the props, nor do I want to constantly change props.

So here's my solution, a Mitsuko/Danaus mashup for 3" props. It uses a 45 degree FC mount, like the one I intended for the original 4" Mitsuko X. I don't think FC standoffs should ever be structural, but in this case, with the frame supported all around, the FC standoffs can bridge the gap between the plates for a little additional support. Put a pod on top, the battery on the bottom, should be pretty straightforward.

As usual I started with SketchUp to locate my mounting points, borrowing parts from other designs as starting points. 

That then gets brought into Illustrator as a guide. I made the perimeter more butterfly-like, with more material up front for the inevitable impacts. The arms were made more flowing, with more material between the center and the motors, and I drew up a pod as well. Cam tilt will be adjustable, for 0-20 degrees or so. 

Then I got another idea. If I made it a bit of a dead cat, then it would look even more like a butterfly, and there'd be room for the fpv cam to go up front, eliminating the pod up top. This would make it simpler, and give the fpv cam an unobstructed view, especially with the 0-10 degrees of tilt this thing would probably run. So here's that: 

Now, this is a low performance slow flyer, but at this point I'm kinda excited. Here's a quad shaped like an butterfly but not one line is purely decorative, which fits perfectly with the form follows function ethos I try to impose on myself (but don't always follow).

Here's the first prototype, lookin' nice!

I put holes for the FC stack on both the top and bottom plates, thinking that I'd run nylon standoffs all the way to the top to stiffen up the structure, but holding the frame in my hands, it really seems more than stiff enough as is. So that's one nuisance avoided.

And here she is built.

Randy (of NYCDFF fame), Josh, and I all built one up the night the carbon came in and maidened them the next day. Great to have fellow maniacs in my wrecking crew!

I used 2300kv 1306's I had ordered by mistake, because I apparently order parts late at night in a drunken stupor. I was hoping that they would be an ok match for something that's meant to be a slow flyer, but they turned out to be terribly underpowered. Mine hovered at about 70% throttle. Josh's and Randy's had 3200kv motors and flew much better. We all noticed that they needed way more P and I, which is not surprising. They have way more rotational mass than a Shrieker, which flies great on stock Betaflight Pid1 pids. We wobbled around the field on stock Betaflight pids before moving on to our Kriegers and Mixukos. 

Meanwhile, I made some changes to the design. I hadn't noticed that the spacing changed when I moved the front motors outwards, so I tweaked the side standoff and FC holes to even things out. I added an extra SMA hole up top, and a pigtail hole down below as per Josh's suggestions. Josh also noted that the FC now fits without a 45 degree offset, but I thought that the USB would be even harder to access that way, so the 45 degree offset stays.

Motor Swap

Chris and Sunnix at my Hong Kong dealer AsiaTees sent me some motors to try, one set being 1306 4000kv's. They're probably intended for 3s only, but since this thing is meant to be flown relatively gently I gave them a shot. So far they're holding up ok to 4s, which is a good thing  – on 3s I was right back to 70% hover. 

I also spent a little more time playing with PID's, and raised roll and pitch P to 7.5. It does indoor proximity well, but try to open it up outside and the weight and drag really kick in – not gonna lie, it's no Krieger or Mixuko. 

Meanwhile, here's some eye candy: Chris, aka Patient 0's build. Never thought white props could be so pretty.

Naming

The first name I had was Oenomaus, which is another genus of butterly, like Danaus. But it's a mouthful and pretentious, so we were all just calling it either 'the butterfly' or 'Butters'. Since I have the sensibility of a third grader I'm going with Butters. The sticker practically draws itself.

And here's a quick little video. We got to open it up a bit more at a different location but we're not allowed to post video from there, so here I am squeezing through the rat's nest I call home, or rather Shendrones World HQ.

This is a pretty straightforward frame, pretty easy to whip up given the experience I had with the Danaus. Rev 2 will be the production version, the only changes being a few different holes in the plates. I try to price everything as reasonably as possible, but the two big ol' plates eat up a lot of carbon, so $90 is as low as I can make it and still have some headroom for dealers. The store listing is here, hope you enjoy it.

Meanwhile, check out what Tyler Steinhauer is doing with his pink Butters. I never thought it would be flyable with an HD cam on top.