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Show HN: I made a 3D printed VTOL drone

tsungxu.com

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Re: Show HN: I made a 3D printed VTOL drone

#11

Post by tsungxu »

bufferoverflow wrote: post #4

It's an impressive achievement for an amateur. He has separate motors for vertical and horizontal flights, which simplifies the design, but creates a rather bad inefficiency, the vertical motors create lots of drag during the horizontal flight. Maybe it's not a big deal, I'm not sure. Making motors rotate would add weight for sure, thus reducing the range.

And the weight (and drag) penalty is ~5% given the actuators and subassemblies for tilting don't come for free either.

This is also the most the penalty will ever be as electric motors continue increasing in specific power, and quite rapidly this century so far.

Re: Show HN: I made a 3D printed VTOL drone

#12

Post by tsungxu »

the__alchemist wrote: post #8
bufferoverflow wrote: post #4

It's an impressive achievement for an amateur. He has separate motors for vertical and horizontal flights, which simplifies the design, but creates a rather bad inefficiency, the vertical motors create lots of drag during the horizontal flight. Maybe it's not a big deal, I'm not sure. Making motors rotate would add weight for sure, thus reducing the range.

Adding a tiltrotor mechanism is surely not worth the added complexity and weight, in this case. You're right though on the added weight and drag from having separate motors and props.

And also iteration cycles slow down, adds cost to development and qualification if making them in-house for larger prototypes.

Re: Show HN: I made a 3D printed VTOL drone

#13

Post by tsungxu »

georgel wrote: post #5

Very awesome! Have you tried to see how much payload it could hold in addition to the drone's own weight?

Thanks, I've not! But given the battery mass fraction is 53% for this build, rule of thumb is about 30% of a VTOL's weight for battery if you want to include payload. So I could just use a smaller 6S battery.

Or I could probably add another ~0.5 lbs or a little more without issue. The lifting motors hover at 45% ish throttle so there is some headroom for more payload without reducing battery mass fraction.

Re: Show HN: I made a 3D printed VTOL drone

#15

Post by Sohcahtoa82 »

asadm wrote: post #6

Pretty impressive! what's the BOM here. That battery seems expensive (most expensive part?)

> That battery seems expensive (most expensive part?)

At first, I was like "Nah, just looks like my RC car battery", but then I Googled it...and it's a whopping $1,305 [0].

I looked closer at the specs and they're insane for a battery as small as it is. They have double the energy density as measured by both volume and mass compared to my RC car batteries [1].

[0] https://www.upgradeenergytech.com/product-page/gold-v1-6s2p-...

[1] https://www.amazon.com/Zeee-Connector-Vehicles-Helicopter-Ai...

Re: Show HN: I made a 3D printed VTOL drone

#17

Post by xnx »

bufferoverflow wrote: post #4

It's an impressive achievement for an amateur. He has separate motors for vertical and horizontal flights, which simplifies the design, but creates a rather bad inefficiency, the vertical motors create lots of drag during the horizontal flight. Maybe it's not a big deal, I'm not sure. Making motors rotate would add weight for sure, thus reducing the range.

Very similar design already used by Wing. I'm guessing they did a fair bit of analysis and modeling of the cost, range, complexity, safety, etc. etc. tradeoffs before settling on what they're using currently.

https://en.wikipedia.org/wiki/Wing_Aviation#/media/File:Wing...

Re: Show HN: I made a 3D printed VTOL drone

#18

Post by tsungxu »

the__alchemist wrote: post #10

I'm curious how this compares to foam-frame designs. Being able to customize it is obviously a big advantage, as is the non-solid-infill of 3d-printed parts. I think for stiffness, 3d-printed frames don't work well for quadcopters compared to carbon fiber, but they sound like a nice alternative to foam for fixed-wing. I think the stiffness concern comes up in quads mainly when they do high-performance maneuvers that…

Yes I used single wall foaming PLA which is much less impact resistant and more brittle vs any foam, even cheap foamcore and especially EPP or EPO. This has definitely been an issue with crashing and rebuilding.

But my first and only other VTOL build was foamcore Readyboard and that took a 12 ft drop onto asphalt with only a slight compression in the fuselage. Never replaced it.

I would add dovetails or other clips for printed sections if I did another printed build.

Yes avionics and propulsion parts are COTS for speed, the Amprius pack is US manufactured but others are all made in China.

I'm starting to see some more Ardupilot used commercially too but yes the UX is janky and unintuitive.

Re: Show HN: I made a 3D printed VTOL drone

#19

Post by the__alchemist »

tsungxu wrote: post #14
truetraveller wrote: post #3

Top speed?

Not tested! But minimum I would say 70 mph. If designing for speed, I'd be looking at a cruise motor and prop that maximizes the thrust output rather than cruise efficiency edit: at least 70 mph

Probably significantly higher even? A normal quad will hit 100Mph +.

Re: Show HN: I made a 3D printed VTOL drone

#20

Post by tsungxu »

snapetom wrote: post #16

As someone who has always been curious about building one but haven’t dove into it, I’d love detailed plans and a beginner-oriented tutorial. I’d be happy to donate/patreon to an effort.

Appreciate that! It's just a lot more effort making long videos with the voiceover/clips/etc.
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