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Comment by walrus01 | Hacker News Reader

The venture money behind some of the larger and more prominent electric VTOL air taxi/helicopter-plane things seems to be betting that by the time they get the hardware design, software, user interface and general safety systems to 100%, battery technology will also have become a lot better.

I'm referring to Joby, Archer, Wisk and similar.

The range is not really good right now with batteries at 255Wh/kg and much worse energy density than Jet-A fed into turbine(s). None of the evtol companies are big enough or vertically integrated enough to come up with some miracle 500Wh/kg battery on their own, so they're relying on market pressure generally to cause their battery subsystem vendors to make some significant breakthroughs.

More directly related to the PR, I saw the video of the JFK to Manhattan test flights and they're being done with only the pilot on board.

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The venture money is betting that the e-VTOL technology can be weaponized. Small, disposable drones have been getting all the attention lately due to the war between Russia and Ukraine. But longer term there are a lot of potential missions for larger VTOL combat aircraft — both drones and crewed.

I would guess that a military version would be a hybrid: electric motors as in all the e-VTOL prototypes, enough battery power to comfortably take off, land and maneuver in combat conditions, and a small hydrocarbon-fueled engine to recharge the battery while cruising.

What problem would a hybrid solve for military? Military doesn't care about emissions and this doesn't offer resilience like fully electric does (recharge anywhere, reliability).

The same problem that a hybrid architecture solves for ships: the ability to use physically small electric motors with very high power density that are mechanically decoupled from the rest of the vehicle. This lets a bunch of designs pull off neat thrust vectoring tricky with much simpler and lighter components than a mechanical thrust vectoring system would need.

(Electric azimuth thrusters are becoming common in large ships for roughly this reason, too.)

> ships

That's a tangent from most sensitive vehicle to weight to the _least_ sensitive one.

The military cares a lot about range, signature reduction, and especially fuel efficiency. Reducing fuel usage reduces the logistical train necessary to sustain units in the field.

https://www.defensenews.com/land/2025/01/22/army-tries-out-n...

Dragging a trailer full of fuel seems easier than dragging a large generator and a trailer full of fuel.

Huh? The regular engine doubles as a generator.

Oh, you’re talking about a hybrid system. I thought you meant all electric like the aircraft from the article. My mistake.

That’s a ton of weight penalty (the most consequential tradeoff in aircraft design) so the design gains of being able put motors in weird places has to be significant.

Once we have higher density batteries it becomes compelling since you can store power for bursty operations like VTOL while using an ICE engine that otherwise wouldn’t have the power, but currently it doesn’t pen out. You need an order of magnitude more energy density from batteries before you can come anywhere close to what combustion engines can do.

How is it going to reduce fuel consumption by nearly doubling the weight?

The 'final' decision was recently made to go ahead with the massive project for this, which is eventually intended to replace the UH60/Blackhawk type platform. Traditional big money defense contractor stuff.

https://en.wikipedia.org/wiki/Bell_MV-75_Cheyenne_II

The military operates more than one type of aircraft. I don't think an MV-75 will fit very well on an FF(X), for example.

Why are larger drones better than smaller suicide drones that can have bombs attached to them and built by the thousands per day in a dark factory?

Range, for one, if what you're referring to as a mental model is 15" prop size quadcopters with an artillery shell strapped to them. For use <50km.

Now look at a photo of a human standing next to a shahed-136 size UAV for a totally different size scale.

https://www.rand.org/pubs/commentary/2025/11/in-europe-the-p...

I see. Thanks for both your answers.

Different configurations are better for different missions. Small suicide drones have very limited range, weak sensors, and can't carry much cargo or a large enough warhead to take out hardened targets. Hopefully we'll never get into a conflict with China, but if we do the platforms will have to be much larger just due to the greater ranges involved.

Can we settle in the middle and trial them for cargo first? Seems obvious for deliveries.

> Can we settle in the middle and trial them for cargo first?

There is an existing market for passenger eVTOL to and from airports. Using that as a beachhead makes way more sense than trying to develop a de novo niche.

Oh market is def there. I mean validating technology on cargo.

> validating technology on cargo

The tradeoff is you have to build a cargo business. That costs money and leadership attention. Racing for the beachhead, given sufficient access to capital, is the more focused strategy. (This is a good example of how bootstrapped versus financed companies can be radically different in their technical debts, time to market, culture and discipline around validating hypotheses.)

I don't see how these style of drone like aircraft could possibly be better for personnel or gear transport over a collective rotor helicopter. A bigger rotor is more efficient, can lift more, and can autorotate to a safe landing after taking the inevitable battle damage and losing power.

I mean I could be wrong, im certainly not an expert in future military design and strategy, but I just don't see any advantages once you start scaling these to the size needed to move humans. The only potential I can see is multi-rotor designs being easier to learn to pilot over a collective rotor design, but I don't see any modern military considering a few weeks off a pilot's training being worth the trade off in range, capacity, and safety.

One large rotor is obviously more efficient than multiple smaller rotors. Where e-VTOL aircraft at least have the potential to win for certain missions is more with cost and availability. Helicopters are extremely expensive and require constant maintenance, and tilt rotors like the V-22 are even worse. But an e-VTOL could potentially eliminate transmissions, clutches, drive shafts, swashplates, etc. Long term we'll see a mix of both technologies being used.

As for survivability, we'll see. Any significant damage to the rotor systems will send most helicopters straight into the ground.

you don't need crazy range to fly between jfk and city .

it's doable to do it today, economically, and solve tons of problems .

in a similar to ev rollout:

solve problem for wealthy people, get the premium, scale cheaper options. Nothing new. Technology of today is ready.

> solve tons of problems

I'm skeptical that air taxis could ever meaningfully reduce traffic congestion to / from JFK. Compared to cars, these would seem to require a significantly larger landing pad and passenger unloading space and need much more safety margin in-between drop offs. Maybe this is competitive vs the private helicopter market?

I wonder what % of traffic is to/from JFK. The subway decently connects much of the city to the JFK air train, but it's a fairly inconvenient journey. Toronto's UP express has made travel to YYZ significantly easier, but I doubt it's possible to construct something similar in NYC.

I love aviation, but I also don't see air travel as being a scalable/affordable solution to this problem. Then again, it's only meant to alleviate traffic burden for a certain segment of the population.

the problem with train it stops ... on every train stop. New york specifically, there are several networks(new jersey, mta, there are lines that are 100+ years old.

In general if you have an affordable enough option you'd never walk into subway, with your several luggages, to travel longer. Train is a decent plan b.

> if you have an affordable enough option you'd never walk into subway, with your several luggages, to travel longer

I'm moderately wealthy and lived in New York for a decade. I take the train between JFK and Manhattan. (Specifically, the LIRR.) It's faster, more reliable and–for me–more comfortable than taking a car. (It's also safer.) If I have my cat with me or I feel like having fun, I'll take a Blade, but that's realistically only shaving like 20 minutes off the travel time.

LIRR is not a dirty MTA train :) Noisy shaky helicopter is not an electric taxi with 6+ motors that gives you more stability with way less noise that flies after take of using wings.

Cars for sure are less convenient.

> LIRR is not a dirty MTA train :) Noisy shaky helicopter is not an electric taxi with 6+ motors that gives you more stability with way less noise that flies after take of using wings

I've also taken the A from Harlem to JFK once. It was fine. Tougher to read a book, like I can on the LIRR, mostly because the frequency of stops means having to constantly be aware of your belongings.

And agree on helicopters. We already have helicopters. Switching them to eVTOLs is a move forward.

if your air taxi is pilotless and electric, why it can't be scalable.

How many people do you think enter/exit JFK arrivals and departures every hour? Where are you going to land all those air vehicles? Is this a shuttle service with many seats? How do you plan for the air traffic for that many people?

About 7000 on average, but let's say 10000 since demand varies. And let's consider doing 10% of them with helicopters. If we average 3 people per helicopter, that's 170 groups in and 170 groups out. If each landing needs 5 minutes of pad time, that's 14 pads. Make it 20 to handle variation.

Wow, that makes it sound significantly more feasible than I would have guessed.

Where do you put those 20 pads in the city?

I'm not sure but there's a whole lot of city available. That half of the problem is easy on a technical level.

Those are all reasonable questions, but if some entity would be able to answer them, of all things, I think JFK, an airport, would be well equipped to handle them.

JFK airtrain carries about 30K passengers per weekday in 2025. how many landing pads would be needed to carry a meaningful % of that traffic alone?

travel time is 5-10 mins with 40 mins to 2hours.

Yes, it is better compared to helicopter. cheaper, less noise. e.g. you can place it more applications, for less money.

Well it's 5-10 minutes once you get to the west 30th st heliport, which can easily take 20 minutes within Manhattan. Plus getting loaded in, cleared for takeoff, and potential for backups at the landing pads, I suspect the gains are much less in practice.

How long does it take to get from a helipad to the terminals at JFK?

JFK and city is a relatively niche and regionally unique market compared to how short/medium range aircraft are used in general. For instance the Joby or Archer product right now wouldn't have the range to fly from a helipad on the Seattle waterfront to somewhere in the San Juan Islands. Or for a flight from Vancouver harbour to Victoria.

it's every airport in every city. In new york only you have 3 airports. its a 200k+ a day traffic.

I'm not sure I agree that they're making that bet (there's lots of market at current ranges IMHO), but even if they were it would be a great bet to make. We're talking about jumping to 375 [1] or even 400 Wh/kg in production cars this year [2] (with prototypes long since shown off). And there's every reason to believe that there's a lot more headroom in this space to improve, and that we will improve rapidly since we're making so many more batteries now.

[1] https://electrek.co/2025/04/28/jeep-dodge-maker-validates-so...

[2] https://www.evlithium.com/lifepo4-battery-news/calb-solid-li...

Joby actually claims their business is viable without significant advances in battery energy density. We'll see. I think this will be closer to an Eclipse Aviation business case than SpaceX.

The upcoming solid-state batteries are around 500 Wh/kg.

But batteries have an advantage over turbines, especially small turbines: specific _power_ density.

I think Beta's CTOL has better economic prospects, if less useful as an air taxi.

More like in a similar (but smaller) role as the Cessna 408 Skycourier, which is short to medium range, unpressurized.

Isn’t the comparison against helicopters for regional and urban transit where EVTOLs hold an edge because of the drastic energy reduction that fixed wing has over helicopters?

I mean sure long term the goal may be to wait for battery density to increase to keep moving upmarket and eat longer and longer flights from traditional aviation, but I don’t think better batteries are a requirement for the initial batch of vehicles.

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