DARPA heavy lift challenge ends with winner at a 3.84:1 payload to weight ratio
52 points by daau 9 hours ago | 37 comments
Neywiny 4 minutes ago
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.
replyegormakarov 4 hours ago
YouTube playlist linked on DARPA site: https://youtube.com/playlist?list=PL6wMum5UsYvbuxFAptr9LYCnd...
replybart__ 5 hours ago
Interesting event, annoyingly bad written AI article
replyVBprogrammer 3 hours ago
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.
replyclose04 3 hours ago
> a conventional single-main-rotor helicopter that weighed 13.3 kg (29.3 pounds) and hauled 51 kg (112.4 pounds)
replyI 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.
klntsky 2 hours ago
What's the problem with connecting two devices together?
replyVBprogrammer 2 hours ago
The splodge on the ground when one of them fails is generally the downside.
reply0-_-0 2 hours ago
Same is true for 1
replyegormakarov 44 minutes ago
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
replyodyssey7 2 hours ago
The prize terms are neat. To incentivize not sabotaging other teams in some way? You would win more if someone were to win.
replystubish 3 hours ago
I assume blimps or lighter than air components where illegal? Or is it just too hard to fly the larger volume around the course?
replyjml7c5 2 hours ago
Your assumption is correct, they were prohibited:
reply>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.
somat 32 minutes ago
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.
replyAs it is, there were some impressive metal fires during crashes, another win for lithium batteries.
anon48293 23 minutes ago
Gases? So vacuum is allowed?
replyAm4TIfIsER0ppos 13 minutes ago
If you can make a vacuum container lighter than air then go for it.
replyLoganDark 3 hours ago
Every post on this website looks AI generated but at least most of it doesn't feel like complete fluff.
replyTeMPOraL 18 minutes ago
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.
replyanon48293 21 minutes ago
Keeps reloading to load ads and LLM spam. Don’t post from this shitty site again pls.
replydyauspitr 4 hours ago
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?
replyballooney 3 hours ago
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.
replyregularfry 4 hours ago
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.
replysnovv_crash 4 hours ago
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.
replyThe 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.
somat 4 hours ago
I am surprised it was not a coaxial design(think the mars copter, but designed for a real atmosphere)
replyK0balt 2 hours ago
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.
replyreliablereason 3 hours ago
I would think coaxial designs suffer as the lower rotor works in more turbulent non laminar air.
replywhatever1 4 hours ago
We have also achieved optimal teapot design for perfect flow thousands of years ago.
replyWe have some times very good intuition and ideas.
cucumber3732842 2 hours ago
As other commenters say, there's physics reasons one big rotor is most efficient.
replyThe 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.
rob74 5 hours ago
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% ?
replylnenad 4 hours ago
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.
replyLeonard_of_Q 4 hours ago
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".
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