So yea ... turns out designing a frame is not as easy as I thought lol.  This is just basically a very rough outline.



Posting this to keep me motivated and disincentivized from flaking on this project which I've been meaning to do in like forever.  The idea here is sub-250 freestyle making use of whoop style AIO FCs and whoop HD split style cams.  I'm still very much in the early stages but I'm thinking 4" tri- or bi-blades, 18XX ????KV motors, 4S 850mAh lipo.  Alu cam cage of course ... cos we're not barbarians lol.  Custom cut lipo pad may be getting ahead of myself at this point.

I've always figured sub-250 is going to require something to give.  My play here is the arms.  They will be basically throwaway.  But removing this constraint should free up considerable weight as far as CF and mounting goes.  My only concern with the arms is that they don't show up as noise in gyro_scaled.  Beyond that, whatevs lol.

I basically plan to rip off things I like about existing frames and combine them into one lol.  

awesome ronin!


i think you could get more rigidity and less weight by shorter arms, an hx not a true-x, just an idea.

Thanks Hugs! You are very astute! I was aiming for as close to a true X as possible for as even a tuning load as possible. Evidently that can't happen with a bus design lol. What I have been doing is looking at the ratio of length to width of frames I really like like the Apex and using that as a sanity check. A rough calc of the Apex indicates a ratio of 1.38x while "Sepukku" here is at 1.24. Does that really mean anything though? No idea lol. But like I said it's more of a sanity check.

As for the arms, yes absolutely. The rendering above is for distancing along the X and Y axis so make sure they are symmetric all around. My plan is to have the front two and back two attached as one piece. But both will be identical since the play here is to not worry so much about arm durability and assume they will be breaking. Only consideration for the arms will be the frame resonance conductivity / gyro_scaled noise. That opens things up a lot.

im so plesaured to see your progress throw in my ideas sry

durability and resonance seems to be the same in the end, is there a difference?


double arm is nice, i have it on my tomoquads kamikaze :-)

I gave that some thought and while I think there is correlation, I also think there is an "efficiency frontier" ... put another way, you can have 10 inch thick arms for super duper durability but I suspect the "resonance threshold" (for lack of knowing the pro term) is much lower. What I'm hoping is that is lower than the durability threshold. That's what I'm aiming for. Hope that makes sense.

Awesome project!

I love how my Gecko 4" flies even though it weighs over 300 g, so making a 4" under 250 g will be amazing.

Do you intend to design and create the entire frame? How about starting from an existing frame and replacing the carbon with custom cut parts? For the arms, making them narrower but 1mm thicker seems to be a good way to make them lighter and avoid resonance.

I thought about that too, Lost ... but then I was wishing several frames all had each others parts. Airblade's weight, Diatone's bling, Takana's arm structure but using Diatone's press nuts, etc. That's when I realized I may as well just try to frankenstein it.

Yea this is not easy my head hurts lol.  Slowly but (sorta maybe) surely ...



The arms are perfectly symmetric on all axis.  It might be hard to tell but 3x M2.5 socketheads will lock those arms into place into pressed nuts.  The arms are 7mm at narrowest portion by the motors flaring out to 10mm by the time it gets to the body.  I'm thinking 3.5mm arms and 1.5mm plates.  I was going to sandwich the arms but man, making sure there's space for holes (so you can get to the stack screws from the bottom) for the THREE different mounting patterns is turning out to be an epic pain in the ass.  

I'm also thinking just 4 top plate mounting points - the 2 at the camera cage and 2 at the rear ... all M2 lol. I just don't know that you need that much to secure the top plate especially for a lightweight 4S. Airblade uses 4 mounting points too but using beefy M3 screws. I'm not sure I want to go that route.

What do you guys think?  I'm kinda excited to see how this thing turns out!


[edit] Crap. Just spotted a huge error and lame oversight. Arms are overlapping the 20x20 and 16x16 mounting holes lol how did I miss that. Back to square 2. Yay.

oohnoo
i mounted my double arms on the bottom of my kamikaze, not inside the body. as i flew it topmounted there wasnt downsides.

As frustrating as it is when going back and forth on one's design, you WILL get there in the end and at that end I'll be waiting here with my 3d printer

Cheers man!

@ph2t
you probably missed its designed for carbon, you need a cnc machine or modify your printer :-)



could this be an option does minimize the stackmounting issue?

You could just countersink the stack holes, then use flat head screws. Unless one of your design goals is to minimize disassembly for maintenance.

dont miss to mention about the usb access to the aio and board direction, something tiny but can make it much less handy.

counterthink is difficult at 1,5mm, probably a 3mm bottomplate buuut with a ronin-logo cutout? :-)
i like the idea of a very thin topplate up to 1mm, never broke one

(03-Mar-2021, 03:07 PM)hugnosed_bat Wrote:
could this be an option does minimize the stackmounting issue?

Great minds think alike hugs lol ... I had that in mind specifically. But I did figure it out though.



General concept - still need to clean and bling it up. But you see the idea here. And what I really like about this compared to the prior design is there's a bit more mass along the length which should help with transferring torque movement to the body ... lol that probably makes no sense.

(03-Mar-2021, 04:01 PM)Sugs Wrote: You could just countersink the stack holes, then use flat head screws.  Unless one of your design goals is to minimize disassembly for maintenance.

You nailed it, Sugs. I always appreciated the ease of stack access since I always break things or find the need to change things around. As much as the Apex is handily my favorite freestyle frame, the concealed stack screws just drives me up the wall lol.

(03-Mar-2021, 04:35 PM)hugnosed_bat Wrote: dont miss to mention about the usb access to the aio and board direction, something tiny but can make it much less handy.

counterthink is difficult at 1,5mm, probably a 3mm bottomplate buuut with a ronin-logo cutout? :-)
i like the idea of a very thin topplate up to 1mm, never broke one

Lol ugh ... I can't tell you how pissed I was when I used a whoop FC on the Katana only to find that a standoff was blocking the USB port completely lol. Until iFly pointed out to me that there are another set of standoff holes I could have used lol. Also, how about the SD card and record button on these whoop HD split cams ... LOL. So many doodads to consider. I may have mentioned this frame has split style HD cams in mind for the flight footage.

In addition to weight savings, that's why I am only using rear standoffs along with the camera cage to mount the top plate so the whole length of the sides will be wide open for any sort doodad. I stole this one from Airblade's Transformer mini. Granted, he uses beefy M3 standoffs ... but ... sepukku!!!! lolll.

Did I mention what that means? So the whole play here is forget about durability. Let's just get a sub-250 ripper that can take an aggressive tune. Every flight, a suicide mission lol. Sepukku is the samurai term for "ritual suicide"

GAHHHH ... cam cage measurement was too narrow. Back to square 2. YAY!!! lol