Yeah I'd be interested to hear more about what the options might be. Also curious why it is that DARPA thinks this is solvable, but no one has come close yet.

Why do you find it ethically ok to continue to support the Department of Defense/War?

From the rules:

>110 pounds is the minimum payload weight to receive a qualifying score.

Maybe "edge case engineering" is precisely what they're looking for? Get people to think about beating the rules with cheesy strategies, in hopes some of those could, with some cleverness, scale up and evolve into proper, broad-range solution - or at least become a key previously-missing component of one. But even if it can't, very narrow capabilities can still be useful too; military isn't beyond doing silly things if they offer enough tactical advantage (enough to offset extra burden on logistics, at least).

How would you build a bullshit solution to move 2.5 pound around a 5 mile course (maneuvering) with a vehicle weight below 0.63 pound? I think if you solve that it’s not a bullshit solution but actually useful.

Giant hot air balloon for lift + 4 rotors for steering? It wouldn't be fast, but it might work [in low wind conditions].

The container required to hold 100 m^3 of compressed gas easily breaks your weight limit. Viable but not viable given the rules.

Not allowed by the rules.

If the truck killrate is 90% what is it for troop transports? How do infantry get in and out of position?

I'm looking forward to the DARPA Challenge to create a service where you can sign up to be emailed about new challenges. This one started October, 2025. More details at https://www.darpa.mil/research/challenges/lift/competitors

"Phase 1 | Launch

October 2025

Special Notice publishing (Oct. 23): DARPA publishes a Special Notice to broadly announce the Lift Challenge and solicit innovative design concepts.

Website launches (Oct. 23): DARPA publishes a Special Notice to broadly announce the Lift Challenge and solicit innovative design concepts.

Rules and prize announcement (Oct. 23): Detailed draft rules and prize structure are announced, specifying objective and subjective judging criteria."

> Generally I think of them as longer running challenges.

Given how outlandish the ratio requirement is compared to currently available products I expect this one will be recurring for at least a few years similar to what happened with the self driving challenge 20ish years ago.

this competition was announced October last year. IIRC registration ended sometime Q1 this year.

I saw https://www.youtube.com/watch?v=tohImHa4f5U (Hoarder Sam, "I'm building a drone for the DARPA lift challenge") the other day and it was a pretty good discussion of the "shape of the envelope" of the problem (and what kind of lift ratios actually exist in modern air vehicles), and particularly how they've set up the constraints to eliminate a bunch of "easy" approaches.

It also reminded me that for the first round of the self-driving grand challenge, none of the vehicles even completed the course :-) They really are trying to encourage "out of the box", or at least "not in the obvious box", designs...

It doesn’t prescribe batteries as far as I can see. You can also build a gasoline powered vehicle which would get you roughly 6 times the energy density.