Been working this for a few months now. It’s not a crazy hard problem - but it does break the mold of distance and speed taking priority over capacity. If you have any questions feel free to ask. I can get into the pros/cons of all the various options and tuning knobs.
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.
The tunable influences on a rotor are primarily velocity (rotation speed) and surface area (radius). Conceptually it’s more similar to something like a human powered helicopter (https://en.wikipedia.org/wiki/AeroVelo_Atlas) than you might expect.
> Competitors must create an aircraft that is both lightweight and powerful – lifting at least 4x its weight while flying a 5-nautical-mile circuit course.
I'd make it 50NM. 5 is way too easy to bullshit with edge case engineering. Alternatively, set a minimum payload capacity of something like 100kg.
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.
The military is waking up to the need to adapt frontline logistics. With killrates of 90% for traditional trucks in the Ukraine war, without resupply missions by UAVs/UGVs holding positions is impossible now.
on foot (not 20km, usually its something like 3-5km AFAIK, 20km is the width of both sides strongpoints + no-mans-land between), or on some fast and agile one-way craft: motorcycles, buggies, e-bikes
the key idea is that you need something which can get you onto the enemy position either before hunter drones take off, or that a drone won't take out the whole complement, hence the uselessness of trucks
going on foot is not really due to the human wave nature of the attacks, but rather its like WW1 stosstruppen - they use whatever cover they can find and a squad of 4 on foot is much easier to go through bushes used as cover or when weather is not suitable for flying
of note here is that trucks were not really used for transport on the tactical level on the frontline, however lately (with drones from destinus) logistics runs in the rear have also become a problem even 100km+ deep - thats where the 90% killrate figure comes from
> however lately (with drones from destinus) logistics runs in the rear have also become a problem even 100km+ deep
That is quite interesting but in light of that my original question remains (except shifted 100 km back) what about troop transport? Are the combatants suffering a 90% killrate on all their large vehicles near the front or if not then what is special about logistics runs?
Also .. if that were the case russia would not find volunteers anymore, as the large majority of russian soldiers in Ukraine are there by free will, not because they were force drafted.
This is being announced to us or everyone right now? It's only around 10 weeks away: that seems surprisingly close. Have some folk already been made aware & have they had time to build for this DARPA Challenges? Generally I think of them as longer running challenges.
> 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.
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.
Hate that "warfighter" has entered our vocabulary. It's so kitsch...
Been working this for a few months now. It’s not a crazy hard problem - but it does break the mold of distance and speed taking priority over capacity. If you have any questions feel free to ask. I can get into the pros/cons of all the various options and tuning knobs.
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.
The tunable influences on a rotor are primarily velocity (rotation speed) and surface area (radius). Conceptually it’s more similar to something like a human powered helicopter (https://en.wikipedia.org/wiki/AeroVelo_Atlas) than you might expect.
Why do you find it ethically ok to continue to support the Department of Defense/War?
> Competitors must create an aircraft that is both lightweight and powerful – lifting at least 4x its weight while flying a 5-nautical-mile circuit course.
I'd make it 50NM. 5 is way too easy to bullshit with edge case engineering. Alternatively, set a minimum payload capacity of something like 100kg.
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].
https://www.darpa.mil/research/challenges/lift/rules
Forbidden in 3.7
Rules exclude that approach.
CATL is working on 12000 Wh/kg air batteries, they will solve this problem, give them the prize.
Hydrogen-filled balloon wins
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.
The military is waking up to the need to adapt frontline logistics. With killrates of 90% for traditional trucks in the Ukraine war, without resupply missions by UAVs/UGVs holding positions is impossible now.
If the truck killrate is 90% what is it for troop transports? How do infantry get in and out of position?
on foot (not 20km, usually its something like 3-5km AFAIK, 20km is the width of both sides strongpoints + no-mans-land between), or on some fast and agile one-way craft: motorcycles, buggies, e-bikes
the key idea is that you need something which can get you onto the enemy position either before hunter drones take off, or that a drone won't take out the whole complement, hence the uselessness of trucks
going on foot is not really due to the human wave nature of the attacks, but rather its like WW1 stosstruppen - they use whatever cover they can find and a squad of 4 on foot is much easier to go through bushes used as cover or when weather is not suitable for flying
of note here is that trucks were not really used for transport on the tactical level on the frontline, however lately (with drones from destinus) logistics runs in the rear have also become a problem even 100km+ deep - thats where the 90% killrate figure comes from
> however lately (with drones from destinus) logistics runs in the rear have also become a problem even 100km+ deep
That is quite interesting but in light of that my original question remains (except shifted 100 km back) what about troop transport? Are the combatants suffering a 90% killrate on all their large vehicles near the front or if not then what is special about logistics runs?
> How do infantry get in and out of position?
They don't. Life expectancy of a Russian on the front line is hours. You just send in another wave.
If that were the case then there wouldn't be anyone there to receive the resupply to begin with.
Also .. if that were the case russia would not find volunteers anymore, as the large majority of russian soldiers in Ukraine are there by free will, not because they were force drafted.
Edit, I forgot, most are not aware of that:
https://www.rferl.org/a/russia-ukraine-conscripts-war-combat...
On foot, walking 20km+ to the position.
Quads and dirt bikes afaik.
Armored carriers if avaiable.
This is being announced to us or everyone right now? It's only around 10 weeks away: that seems surprisingly close. Have some folk already been made aware & have they had time to build for this DARPA Challenges? Generally I think of them as longer running challenges.
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.
Darpa.mil got slashdotted? Wow. The folks who invented the internet...
Really just a battery challenge.
Possibly against laws of physics at energy density of 4x?
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.
[stub for offtopicness]
[title fixed now]