They aren’t really all that exposed while folded. But if you ever break one just print a replacement.
Also, keep in mind that during flight there isn’t any stress on these because the thrust holds the arms open. The hoop will also hold the arms open. They are more a setup aid than anything. So if you broke one on the way to go fly I wouldn’t let that stop you from flying.
I redesigned my hinge stops to be more narrow and contour the hinge better:
Here are the files:
Hinge Stops - Top.stl (110.6 KB)
Hinge Stops - Bottom.stl (110.6 KB)
Here is an update to the pre-charge knob. I made it stronger and adjusted the orientation to be straight.
I recommend using a 10 ohm resistor or less with it.
Here are the files:
Pre-Charge Knob - Knob.stl (1.9 MB)
Pre-Charge Knob - Shell.stl (391.5 KB)
Pre-Charge Knob - Hub.stl (295.5 KB)
Also a link to the resistor I am using now:
http://d.digikey.com/R00N0o9XR71000k0SfKaHpH
I added battery tracks to the legs for the option of flying with 6 batteries.
That’s a lot of battery!
Here are the files:
T-Bar and Miter Track Horizontal - Top Left.stl (128.3 KB)
T-Bar and Miter Track Horizontal - Top Right.stl (632.9 KB)
T-Bar and Miter Track Horizontal - Bottom Left.stl (128.3 KB)
T-Bar and Miter Track Horizontal - Bottom Right.stl (604.6 KB)
The lower batteries plug into this Xt 150 connector holder.
Here are the files:
Xt 150 Mount (Lower) - Holder.stl (277.5 KB)
Xt 150 Mount (Lower) - Hold Down.stl (57.5 KB)
How did you wire up the 2 extra batteries internally?
Here’s a copy of his pic that he sent me. I’m curious of those rubber gasket looking prop protectors in the center holes. What are those?
https://discourse-openppg-prod.s3.dualstack.us-east-1.amazonaws.com/uploads/db1930/original/2X/8/8bf8d79aa2c670daeaf73b88ce2baa520045f0ba.jpegNotice in the picture that all of my inputs are connected. So as soon as I plug in the batteries they are connected in parallel to each other even with the switches off. Turning on one switch connects all batteries to all ESCs. Turning on the second switch will make that switch carry half of the load. If a switch fails during flight you still have power to all motors from all batteries. I can fly with or without the other two batteries without effecting any of the above.
I found these rubber grommets on Amazon:
I opened up the holes in the carbon with a Dremel tool so the circumference of my oval shaped hole matched the circumference of the grommet.
I have pre-ordered the V4 kit, Very excited to build it and include some of your “Upgrades”. I live in Utah county, any chance I could come up and see your unit?
Absolutely! PM me and we can discuss when and where to meet.
What are these Paul? They look like the balancing leads but I don’t know how they would be useful on the rig. I understand why they would be useful on the charger.
The most important piece of information when flying electric is to know the voltage of the lowest cell. The only way to measure that is through the balance leads. Right now those go to my low voltage alarms that I bought on eBay but eventually they will go to a battery monitoring system which will display the lowest cell on a display on the gooseneck bar.
@GliderPilot Did you think about 3d printing flexible filament for creating custom grommets to fit the existing holes to avoid having to Dremel? (This is me scraping for 3d printing ideas for when I get my batch 4 since you’ve covered almost everything else I’ve thought of 
You do great work!)
The hole had to be opened up a little as it was. I did that last year the details of which are above. Then to make up for the thickness of the grommets they needed to be opened up a little more. I could have bought smaller grommets but the props wouldn’t have fit. I think the size grommet I used is just right.
I’ve never used flexible filament. It would be fun to design a custom grommet. I’ll let you have that fun. Thanks for the compliment.
This is how I mounted my voltage alarms for now using balance lead extensions:
I’m not impressed with their accuracy but they are better than nothing for now. Eventually I will have a monitor on the gooseneck bar to display the voltage of the lowest cell.
The balance leads from the batteries plug into mounts like these:
Plugging the leads in like this also keeps them out of the props without fussing with other tie down methods.
Not sure if PM worked, Any chance you’ll be out this weekend?
I like your line of thinking. What will it take to get a display running that shows voltage of the lowest cell? That sounds like the perfect solution. Have you had one of these go off mid flight yet? Also what are the red components where the wires come out of each esc?
There’s a lot to figure out to be able to accurately monitor voltage of that many cells all at once on the same processor and to design a PCB for it. In the meantime Zach and Paul are working on something similar for batch 4. So we are debating if we want to finish our ideas or wait and see what they come up with.
The alarms I am using are often inaccurate on at least one cell so they almost always sound right before I land. They don’t go off mid flight though but I keep an eye on my total voltage and adjust throttle as needed as to not drop below 42v. Mid winter I damaged a couple cells mid flight and didn’t have these at the time. The resistance of the cells are higher when it’s cold so the voltage sag was greater which led to damage that could have been prevented with a good monitoring system. I also learned not to fly with cold batteries.
