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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.
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?
Coaxial gets you compactness, not efficiency, that's the tradeoff. Losing that top-bottom rotor interference (~15% penalty typically) matters way more when payload ratio's the scoring metric than fitting in a smaller footprint.
Coaxial rotors lose efficiency to aerodynamic interference between the two disks, each rotor works in the other's downwash. That's exactly why it's not the go-to for max lift per watt, single rotor stays cleaner.
>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.
Makes sense given the metric they're optimizing. Buoyancy scales with volume, payload fraction with structure, so allowing LTA would've turned it into a blimp-sizing contest rather than a test of airframe efficiency. Cleaner comparison this way, even if less flashy.
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".
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.
"Payload to weight ratio" bugs me a bit, that's just payload fraction. 3.84:1 means payload exceeds empty weight, which for a lifting rotorcraft is genuinely wild. Helicopters usually top out way lower.
