bennymack's blog View Details
Posted by bennymack | Feb 19, 2020 @ 09:03 PM | 2,880 Views
I've been busy engineering race quads for the 2020 season. I want something that's aerodynamic so the js-1 caught my eye with its streamlined pod. I also like durability and the carbon arches inside the pod seem like they should protect the stack pretty well. As an added bonus, it should be a pretty good all weather flyer with most everything enclosed. This is also my first ever build with a futaba rx (r2000sbm) to pair with my new-to-me futaba 16SZ. Full parts list at the bottom...

Let's start with a picture of the finished product.

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I started by assembling the frame. Use the included bolt and washer to install the press nuts on the top plate (not pictured). I used 14mm bolts on the outboard arm holes and the included long bolts for the inboard 30.5mm spacing holes. Just threaded them in enough so the ends were coming through the other side

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Then install the included 3d printed m3 washers. These are needed to keep the ESC from touching the bottom plate.

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Posted by bennymack | Feb 08, 2020 @ 10:57 AM | 5,022 Views
Been a while since the last one and I've built many quads since then but this is one that turned out really well and I'm really proud of. First, a pic of the finished product... 275g with battery strap, ummagrip lite, and 51466 props. Build manifest at the bottom.

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The goal was to build a very aerodynamic quad which I think I achieved but I wasn't expecting the build to work out so well. It's not only aerodynamic and reasonably light, but also pretty easy to build. While that build difficulty may be subjective, when I think of the steps to build one of my lexielites (I have a fleet of four), this has waaay fewer steps. I feel like it's worth it to put this out there in case anyone else wants to slap one together. The steps are all pretty simple and there's not a lot of fussing around, it all just kind of works..

Let's get started with the flight controller and receiver. I designed a simple 3d printed adapter to hold them (and eventually the 4in1 ESC) together. Use three short wires (20mm or so) to connect the r-xsr to the talon f7 v2. (I already flashed the r-xsr with the f.port firmware). NOTE: when hot gluing the receiver to the little tray, don't have it too far inboard as the ESC can potentially press on it and engage the bind button so the RX is always in bind mode

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Then on the top, I use the plug that came with the r-xsr as a way to disconnect the POD. Simply solder the wires on the talon in the order shown.

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Posted by bennymack | Feb 07, 2017 @ 08:05 PM | 6,400 Views
Will it fly? More like, will it build?

My entry in the never ending race to make the smallest brushless FPV quad. I don't intend to go any smaller. Of course I said that about my SIXTYFIVE from rctop-shop.de...

This particular design uses an emax femto FCB, tiny ant ESCs, racerstar BR1103 10000kv motors, QX70 40mm four-bladed props, frsky XM, boldclash F-01, and m2 hardware. It probably could be a little smaller for smaller props but I think this is the bare minimum to use the 40mm. There is 1mm clearance between the tips of the blades. Motor to motor is 58mm and tip to tip (straight on) is about 81mm.

The battery will be held in place with rubber bands and will ride sideways so that front on impacts will press the battery into the rubber bands rather than lengthwise through them.

The ESC power/ground/signal wires will go through holes in the arms. I didn't want to weaken the arms too much so I widened them towards the base a little. Then the holes are also slanted a bit on the bottom to give the wires a little extra room. The plan is to solder to the femto first, poke the wires through, solder them to the ESCs, then lay them flat and tape/heatshrink to the arms.

Then there is a bottom plate that will protect the ESCs and give the battery a place to be strapped. I intend to cut the head off some 2mm bolts, slot the end, and use them as set screws that can then be attached to standoffs on the top of the frame.

The propellers will overlap the camera holder a little but I'm planning to use 6mm high standoffs while the props will be 10mm above the frame so they should not hit.

I printed the first version of the frame and it looks like I'll probably want to make the rubber band nubs bigger. The indentation for the femto processor may not be deep enough. When I get the parts I'll start fitting them and see what needs to be updated for sure. The camera holder is still very much a work in progress.
Posted by bennymack | Jan 18, 2017 @ 10:29 PM | 6,514 Views
Not even my latest build. But I'm pretty happy with it. In comparison with my pico owl build, which was 59g *without* fpv, this guy is pretty impressive numbers-wise. 52g dry with FPV and guards. That's with bigger 2035 props than the pico owl. If that sounds interesting to you - read on!

First, I printed one of these Emax Femto flight controller base 20mm x 20mm, the one without the bolts holes. I hot glued my femto to it with the USB facing up.

Then I use some of this incredibly low profile double sided tape to stick it to the bottom of the frame. I added some more hot glue to be safe.

Using the same tape, I stuck four tiny ant ESCs to the arms. Then wrap them up with some heat shrink to really hold them on well.

Install the motors. Feed the motor wires through past the end of the ESCs on the power/signal/ground side and fold them back towards the motor side. Trim them to length and solder.

Connect the power/signal/ground to the femto. Very short wires can be used in this particular setup.

Solder four wires (+/-/sbus/telemetry) for the furious microRX and feed them up through to the top in the same hole as the motor wires. Trim to length and solder to the RX.

Feed a 1.0mm connector through another motor wire hole. Trim to length and solder to the 5v/ground next to the rx2/tx2 on the femto.

Install prop guards, props, and bottom plate. I used a couple extra standoffs to protect the all in one camera/vtx. I will post the 123dx file for the bottom plate later on. It could have been chamfered less for the USB and less cut out vertically as well...

One thing to note is that this setup requires a custom mixer in betaflight. Since the femto is upside down, motor one is connected to S3 for example. I'll dump the mmix I used and paste in it here when I get a chance.

I'm guessing not a lot of people are building them like this but I think having the femto and ESCs on the bottom really makes for a nice, tidy, light, and low profile build.
Posted by bennymack | Nov 08, 2016 @ 01:00 PM | 6,786 Views
Here is my most recent build. I have built things since the armattan 128 but this one is probably my favorite.

It's a FlexRC pico owl frame, piko blx fcb, cicada 2in1 10A ESCs, furious fpv micro frsky RX, eachine TX-02 AIO 25mw camera/vtx, furious fpv 1935 four bladed props, and turnigy bolt lihv 2s 500mah packs.

Building it was a challenge. The nylon prop guard needed to be trimmed with a very sharp knife to get all the leftover burrs from the 3d printing process. The props were not all the same length so some of those needed to be trimmed as well.

I started with the shortest 2mm standoffs I had but kept running out of room so I ended up with 6mm or 8mm between each component. The RX turned out to be thicker than expected as did the motor and power wires. Since there is pretty much zero clearance between the cage and the ESCs front to back, I had to route all motor/power/signal wires to the left and right. The benefit of going through all this is that the cage can be removed with four 3mm nuts.

I ran the UART1 TX/RX out the top with some dupont connectors so I can tune the FCB without a USB since it's inaccessible anyways (and I burned out the USB connector ) I also ran 5v/gnd to the front to power the VTX/camera combo. I love that the piko blx has a built in regulator. I didn't need the PDB feature though.

Then I have UART2 sending telemetry to the furious fpv RX. Remember to check the TELEMETRY box in the configuration tab! Need to set the UART2 to frsky in the ports tab. I also needed 'set telemetry_inversion = off' and 'set sbus_inversion = off'. The RX is connected to the satellite rx which is UART3 RX.

I turned the rates down to like 0.50,0.50,0.40 and upped the expo to 0.50 on all channels and it worked out pretty well for my first race. Flying it in the backyard it feels like it needs more throw.

Almost forgot the most important part! Weight with fpv is 66g, and AUW is 98g with the bolt flight pack.
Posted by bennymack | Jul 29, 2016 @ 04:22 PM | 6,939 Views
I have been building my cloverleafs the same way for a while now. They're definitely not the best but they're essentially free and I've robustified the design a bit based on *ahem* field testing...

I start with 0.56mm welding wire.

One robustification is that I put a 90 bend on a very short section, about 1.5mm (as short as I can make it really). This is to increase the strength the signal feed area. I found that the wires would pull out from the central solder blob pretty easily.

Then I put three more bends at 11.89mm, 26.46mm, and 13.09mm respectively.

I've been using cable salvaged from wifi antennas. Bind plug for scale.

I lightly tack on the wires at 120 to each other. This is after fluxing and tinning everything of course.

I pull a single strand out of a chopped piece of 120v cable and tack it on with some solder on one end then wrap it up and down twice. This is robustification #2. It adds a lot of strength to the antenna wires. These are NOT going to come off.

Then I flux them even more and saturate them with solder.

Start making lobes by bending them to semi circle by hand.

Bend them to the right 45 for RHCP (or left for LHCP if that's your thing). Get the ends to line up to the signal feeder so they all just sit there.

Flux + solder blob = done!

These little coaxials are so flexible, plus the active element so robust, I haven't broken one yet.