DARPA heavy lift challenge ends with winner at a 3.84:1 payload to weight ratio | Hacker News Reader

DARPA heavy lift challenge ends with winner at a 3.84:1 payload to weight ratio

dronexl.co

72 pointsdaau50 comments

Interesting event, annoyingly bad written AI article

Slop city, it felt like I was having an LLM chat.

This is the honest take.

Load-bearing, even.

Utter garbage by the "authors" of this post. Shame on you Haye Kesteloo. It takes three sentences to not vomit this crap into the world.

I wonder if there’s a way to hide comments regarding AI in HN, complaints included.

This article read like Claude output placed inside massive ads. 0 value above telling Claude to summarize the source for me. Except, the source was not linked as article link.

YouTube playlist linked on DARPA site: https://youtube.com/playlist?list=PL6wMum5UsYvbuxFAptr9LYCnd...

Wow, there were a bunch of very interesting designs, Probably telling the winner was a very tradition design, but I love seeing wild stuff being tried.

The kite copter was my favorite, but the large rotor powered by small tip rotors was a close second.

Kite rotor?

Can be seen here at 1m30s: https://youtu.be/2x2W3mwERiU?si=ySQh_-QMCetehasK&t=90

Interesting. What’s the kite supposed to do?

My guess is act as a wing in a forward flight mode, Sort of like a hang glider.

A nearly 4:1 ratio makes a 25kg drone very interesting from a personal mobility perspective. Something you could fly a few miles with and then easily roll around an office. Sadly scaling in aerodynamics is notoriously non-linear.

> a conventional single-main-rotor helicopter that weighed 13.3 kg (29.3 pounds) and hauled 51 kg (112.4 pounds)

I think this was the sweet spot for now and we'll need to wait for anything that maintains that ratio at double the carrying capacity.

What's the problem with connecting two devices together?

The splodge on the ground when one of them fails is generally the downside.

Same is true for 1

Can this stuff autorotate? You could also take emergency parachute with you (~5kg), would require flying at least at 500ft or something to be able to deploy it

I saw a lot of novel designs for this but what was interesting to me was Hoarder Sam's design which I followed for a bit. He started without a tail rotor but did have one large main rotor. Then his design kinda evolved to use a tail rotor. Didn't use a swash plate, but by the end of it he was a short hop away from basically just an efficiently designed conventional helicopter. Like carcinisation.

Hunh so for pure lifting our standard helicopter design is apparently the best. How did we stumble on the perfect design half a century ago? Was it sheer luck and constraints or can you actually do the math for this to work it out?

We have also achieved optimal teapot design for perfect flow thousands of years ago.

We have some times very good intuition and ideas.

The article makes reference to this being expected from the physics, but I don't think it's particularly intuitive why it should be the case. Unless it's as simple as smaller swept areas needing higher tip speeds for the same lift? That would make the energy loss to drag worse for multirotors.

Higher aspect ratio blades are more efficient. It maximises disc area for a given mass of blade (linear-squared relationship). Blade is held straight due to tension not purely from torsional strength, so it can be made from a material with high tension strength like carbon fibre which is light. Also it positions the fastest moving blade area far out from the fuselage where there is less blown-drag.

The downside is that the tail rotor is purely loss.

Potentially a similar efficiency could be achieved with two large rotors, but then you end up needing to use cyclic roll to counter drag-induced cyclic yaw, or adding extra pitch mechanisms on each motor mount to make differential yaw.

So the wiggle room for efficiency is in the mechanism for counteracting yaw? Either the weight or energy expense of running a tail rotor or quadrotors or variable pitch mounts (or some other clever mechanism)?

Same physics that drives wind turbines to be as large as possible, I believe.

I am surprised it was not a coaxial design(think the mars copter, but designed for a real atmosphere)

I would think coaxial designs suffer as the lower rotor works in more turbulent non laminar air.

Twice as much rotor weight moving the same cross section of air. What might actually work would be a coaxial where rotor A and rotor B swept different parts of the rotor disc at different rotational speeds, to get blade speeds closer over the whole area, or the twin rotor front and back design, but apparently the structural weight of high power distribution for the dual rotor design is a significant problem, sweeping less disk for the weight than a single rotor system. I think a big part of it is that disk area goes up at the square of rotor length, so having multiple rotors costs you the advantage.

For a given lift, a larger, lower speed rotor is strictly more efficient than a smaller faster one, all else being equal. So no surprises that when efficiency matters we don’t see quadcopter-type designs. The reason they became ubiquitous is because they are so mechanically simple, all the control can be done with cheap electronics, no need for the great mechanical complexity of a swashplate.

As other commenters say, there's physics reasons one big rotor is most efficient.

The reason the earliest rotary wing aircraft took this configuration is because where was no other choice with the technology of the time. They had to pick the most efficient option for it to be cost effective and have useful capacity.

The prize terms are neat. To incentivize not sabotaging other teams in some way? You would win more if someone were to win.

I assume blimps or lighter than air components where illegal? Or is it just too hard to fly the larger volume around the course?

Your assumption is correct, they were prohibited:

>3.7 Heavier than air: The UAS must be a heavier-than-air aircraft. The use of any lighter-than-air gases to provide buoyant lift is strictly prohibited. Teams may use chemically inert gases for subsystem actuation, safety inerting, and component rigidity, provided that there is no buoyant advantage and the gas is contained in components operating at pressures indicative of mechanical function.

https://www.darpa.mil/research/challenges/lift/rules

Someone did fly a sort of balloonocopter, a quad copter that used inflated balloons as the cross arms, My disappointment is immeasurable that they were not allowed to use a lifting gas in it. I mean, it flew poorly anyway, but seeing as it is an unmanned vehicle, I would have used hydrogen as my lifting gas, and then when it had a catastrophic failure it would get a viking funeral for free.

As it is, there were some impressive metal fires during crashes, another win for lithium batteries.

Gases? So vacuum is allowed?

If you can make a vacuum container lighter than air then go for it.

I'm currently reading Diamond Dogs, Turquoise Days by Alastair Reynolds. In the second book, there's a water-world where there are airships, and a whole city held aloft in the air by "vacuum bladders".

I'll admit when I first read that detail in a description of the blimp-like airship the 2 characters are riding right at the beginning of the book, it took me a second to realize exactly what it meant. My understanding of airships like blimps and such hinges on something being in the gas bladder... But yes, nothing is certainly lighter than something! I haven't yet encountered any technical description of how the bladders are constructed, which I look forward to reading.

I think there was something similar in Neal Stephenson's "The Diamond Age".

You need to construct a sphere that is strong enough withstand 1 atmosphere of pressure but also lighter than the weight of the air being displaced.

In a sci-fi book you would construct your unobtanium shell in space and use them to splash down heavier payload to earth. But the material needed is probably still magic.

I think Reynolds also had smelting in space, where molten metal would be turned into a huge volume of froth using some lighter than air gas. The 'burgs' of metal foam could then gently float down to earth.

> Avidrone Inc.

Nice to see a Canadian company at the top.

It seems like the defense industry in Canada is starting to boom.

Winning $ 1.25 million is great - but I wonder how they feel about not getting the full $ 2.5 million prize because they missed the 4:1 target by 4% ?

They've probably got companies lined up to give them jobs that will pay multiples of those. The runner up is even more interesting, with a slightly larger reason to feel like they should have won it. They did ~3nm (out of 4 iirc) of 4.04:1 ratio.

They probably feel like the athlete who missed breaking a record, like the shipping company which just failed to load the goods in 4 trucks and now needs 5, like the painter who just needed that extra 50 cm on his ladder: "darn, so close".

"Close, but only half the cigar"

Whatever happened to "Close enough for gummint work".

Every post on this website looks AI generated but at least most of it doesn't feel like complete fluff.

I imagine they're expanding a bunch of notes and reports and research into an article, whose total size is not that much bigger than the "meat" of the inputs. The annoying LLM fluff is largely when someone is trying to inflate some simple information in size by an order of magnitude, e.g. turning three bullet points into an article. If you have enough of actual content to furnish an article, well, LLMs are excellent at restyling that into coherent prose.

Yep, that's where the respect comes from mainly. I see some occasional LLM-isms but the article is still fairly dense with actual information.

Keeps reloading to load ads and LLM spam. Don’t post from this shitty site again pls.

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