DARPA Moves Forward on X-65: Plane with no moving control surfaces

Thinking about the fictional Helios in the excellent For All Mankind does make me wonder if it might work in a spacecraft!

Some interesting actual work on fission-powered planes was done: https://en.wikipedia.org/wiki/Nuclear-powered_aircraft but as the article says the niche they would theoretically occupy ended up going away, especially since a crashing fusion-powered plane is a pretty significant inconvenience but a crashing fission-powered plane is a catastrophe. We're not used to thinking of air flight as something with huge amounts of power available to it for very long periods of time, so our intuitions don't match what is possible. Still, I would think these would be very expensive, if for no other reason than that there is no reason to build them unless you meant to make them very, very large. It's the sort of power plant that could make something like the helicarriers in the Avengers movies possible (albeit I suspect with rather more surface dedicated to control and pushing through air) and it would probably have to be a plane, not a helicopter-based system), but even if we had the blueprints in hand we'd be looking at investments sized more like Navy ships than airplanes.

At some point that's like trying to make someone invisible by making their skin--and only their skin--transparent.

It'll backfire when all the twisty complicated still-important stuff on the inside stands out even more.

I don't see the word "plasma" once in the article. That said, neither de-icing nor small surface conduits are new in aviation. The J58 famously bled air overboard to disrupt a boundary layer [1].

[1] https://en.wikipedia.org/wiki/Pratt_&_Whitney_J58#/media/Fil...

Recognising non-goals is a core skill for any technical profession. This is a research project doing completely novel things, and specifically mentions some of the intended use-cases. Of course they’re not the least bit concerned with propeller drones.

Let me give an example for myself. I am not an expert in ML. I come to HN to learn about ML and I feel like I learn a good amount. I try to grok the comments, read the articles, etc. If I stumbled upon a bunch of very, very misguided comments I'd expect or hope that someone would say something so I could save myself some time. I see that kind of behavior a lot when users on HN call out "bad physics" but no one calls out bad aerospace.

Years ago, when I read about the original grandiose plans for the Air Force's Y-2, one of the aspects I thought was very interesting was the ability to create a "virtual airfoil"[1] via the Coandă effect. It seemed like one of those designs that was impractical with a human 100% in control, but that might come around again with computer assistance or a fully computer-piloted aircraft. Pretty neat that someone already made it happen.

[1] https://en.wikipedia.org/wiki/Avro_Canada_VZ-9_Avrocar has a brief discussion of this.

Put another way, the most hardline, fundamentalist Mormon I've ever known was a former boss, who was a fantastic engineer -- and completely incapable of challenging his assumptions in any other area. Ruthlessly logical when it came to system design, but couldn't apply that to anything else.

Point is, you have a lot of adaquate STEM types talking out their ass about stuff outside their domain.

Plus a non-trivial amount of marketing and agit-prop bots, which shouldn't come as a surprise to the crowd that was talking about GPT long before it was cool.

That's very unlikely. This website has not implemented the features that continuously make Reddit worse as time goes by - self-segregated communities and extensive down voting.

That is one hell of a claim...

It has a side benefit of being a subtle intelligence signal if you're the "what about" person, i.e. "I saw the gap/flaw that OP missed, therefore smarter".

This, I think, is an "I'm smart" feedback loop that promotes more of the same behavior. It's a powerful motivator when you're on sites and boards also populated by ostensibly smart people. No one wants to be the dumb one. So you start to get wrapped up in being the bug finder/doubt-conjurer/"what about"-er.

Enough time goes by with those types being uncorrected and you wind up with comment sections that just turn into TTFC (time to first complaint) races, often by people with no practical experience in a domain save a quick wikipedia search or who don't even read tfa but boy howdy they've sure got some thoughts about that field as a "science" and gosh i can't wait to read them.

Of course this is all just an old man grumbling out a theory on a Tuesday. I'm not sure how to fully solve it and doubt there's a general solution. For myself, I was eventually broken of shitty habits like that through what would probably now be considered bullying. Gotta say though; sometimes it works. Sometimes your brain needs its ass kicked into realizing you're a smart cookie but you're not the smartest, and that's okay.

I'm more of a standing desk one right now.

In my experience, it is because most things are not good enough or are unacceptable. You see this in software engineering, technology, and science. Not in this particular case necessarily, but most "innovations" can be shown to be impractical and not good enough through back of the envelope calculations. Yet, the discourse on the Internet is full of these useless things, including this stupidity I remember back at the height of Covid: https://news.sky.com/story/coronavirus-lg-unveils-battery-po...

Pedantry

If 90% of people exhibit some characteristics of the autism spectrum, shouldn't we start to consider the people with none as the ones worthy of a label? Like people with true pitch. We give them a label, not people with less than perfect pitch.

Perhaps pedantry is like true pitch or "perfect" vision. It's actually a good thing. Even if it annoys people who don't have it. I wonder if people with true pitch go through life cringing on the inside every time they hear a wrong note. But they learn to never let on that they notice.

Perhaps the part of pedantry that puts a person on the autism spectrum is not so much the noticing as it is the voicing--the seeming inability to control the expression and calling out a correction instead of just letting it slide.

Some of the press on this talks about weight savings. If they're really serious about that, well... none of their flights are intended to go above Mach 0.7. Possibly they could deploy a ballistic parachute like Cirrus airplanes offer.

It's gotta be a modified engine that lets you extract compressed air.

Doesn't change anything about requiring additional moving parts to control where the compressed air goes and where it goes not. The goal of this entire exercise is not to expel some extra compressed air in places where previously regular outside flow happened, the goal is to control the plane by changing when and where that disturbance by extra air happens.

I didn’t read the original as meaning non-military drones, rather non-stealth military drones.

For example, to the OP’s point, the Predator drone is powered by a piston engine - I’m not overly familiar with other military drones, but stands to reason other UAVs use similar tech.

The high-pressure air must come from a compressor, either a separate compressor or the jet engine compressor.

Obviously it is much cheaper and much more compact to use bleed air from the jet engine compressor, than to include a second compressor, only for maneuvering.

On an aircraft without a turbo-engine adding a compressor would increase the cost and the energy consumption a lot in comparison with the traditional methods of steering the aircraft, so it is not advantageous.

However this method without control surfaces should also be usable with turboprop engines, not only with jet engines.

https://news.ycombinator.com/newsguidelines.html

I also was puzzled by the focus on piston engines and stealth. Just ask why rather then assume something negative; almost always, I find people have a good reason - one that they will never bring up if I attack them. People react: Attack -> Defend; Ask -> Answer. IME, people have a lot of good stuff to say if I give them space, and can sound like idiots of I attack them.

'Why are you focusing on piston engine propeller drones and not, say, passenger airliners or military fighters or all the other flying machines? Do they say that small, non-stealth drones are their goal?'

It was a reasonable design decision to put both types of controls on the prototype.

But if I put chocolate chips in a cookie, claim that the cookie is chocolate-free, and then (when called on it) explain that the chocolate chips were only needed to make it taste good, while working on my cookie recipes - I still have lied.