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on Gopher (inofficial)
URI Visit Hacker News on the Web
COMMENT PAGE FOR:
URI The company building a rotating detonation engine is pushing the tech forward
mc32 wrote 14 hours 41 min ago:
Speaking of detonations, NASA is till interested in nuclear propulsion
to reach Mars. This is reminiscent of projects Nerva and Orion/:
URI [1]: https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsio...
topspin wrote 18 hours 55 min ago:
Weird that the term "drone" is used for what is plainly a missile.
snakeyjake wrote 15 hours 21 min ago:
Some of the first non-apian drones to ever fly were "missiles".
You're going to have to invent time travel, go back over a century,
and murder all of the people who started calling drones "drones" if
you want to win this battle.
1letterunixname wrote 14 hours 49 min ago:
A crushed bit of paper could be a "missile."
The mass media put its thumb on the scale, lambasting phenomena by
reforging certain words to create a culture of fear and taboo using
such example words as "hacker", "terrorist", and "drone".
And while a Unabomber approach to language use is unlikely to
influence anyone, it's important to know the history of multiple
meaning of words because those are additional meanings because a
single word means different things to different people based on
situational factors. To suggest one meaning is more "right" than
another is to champion some people's experiences and invalid
others'.
shiroiushi wrote 3 hours 46 min ago:
>A crushed bit of paper could be a "missile."
As anyone who's played D&D knows, an arrow shot from a bow, or a
rock shot from a slingshot, is a "missile".
buildsjets wrote 16 hours 26 min ago:
No, it's weird that people think that only those dumb looking
quadrotor helicopters are "drones", when "drone" was originally a
term used for an unmanned missile or aircraft decoy. This usage
dates back to 1936 or earlier.
1letterunixname wrote 14 hours 58 min ago:
That R/C planes, helicopters, and toys need bureaucratic government
licensure is only explainable as outgrowth of "helicopter" (pun
intended), fear-based parenting and the elimination of everything
fun that might have the slightest potential risk and the
acquiescence to intrusive control.
carabiner wrote 17 hours 7 min ago:
No warhead and it's meant to be reusable. Very different engineering
for an actual missile weapon that is intended to fly once.
hawski wrote 14 hours 6 min ago:
In certain scenarios it makes sense and is very effective to turn
off GC in Java, because then most allocations would be just a bump.
It is much easier to turn it off than have a system without it and
turn it on.
readyplayernull wrote 17 hours 58 min ago:
Every vehicle is a drone as every algorithm is AI now. Marketing
keeps the world rolling.
nonrandomstring wrote 16 hours 26 min ago:
> every algorithm is AI now
Dammit, I'm still working with computer "programs", you crazy kids!
topspin wrote 17 hours 53 min ago:
Another comment points out the inevitability of this technology
appearing in weapons long before any sort of passenger aircraft.
So the likely marketing reason is a bit of gaslighting to avoid
"issues" with some investors.
morkalork wrote 17 hours 55 min ago:
Cruise missiles that have wings and follow flight plans rather than
ballistic trajectories are pretty much just drones and always have
been.
jtriangle wrote 19 hours 1 min ago:
All of these hypersonics companies are targeting mach 5 for a reason,
which is that the material science hasnt caught up yet. The bet seems
to be that they'll either be ready once it is, or they'll be the ones
to develop it and start raking in a mountain of military industrial
complex cheese.
Not a bad goal, but the thin vernier of 'passenger flight' leaves a bad
taste in my mouth. This tech is for munitions delivery first, the
meatbag ferry is squarely a side hustle, and I wish they'd be honest
about it.
JumpCrisscross wrote 14 hours 19 min ago:
> mach 5 for a reason, which is that the material science hasnt
caught up yet
The X-15 did Mach 6 in the 60s. What materials and components are you
referring to as cliffing us at Mach 5? Isnât the simpler
explanation that hypersonic flight is defined at Mach 5?
jtriangle wrote 12 hours 23 min ago:
The X-15's had to be repainted after every flight, because the
ablative coating was designed to wear off at speed. That's a huge
expense, in both time and money. Worth it for a research craft, not
worth it for any practical use.
In terms of materials, most of the newmake ultra fast aircraft are
using inconel, which is more viable than it was back in the day.
Some are using ceramic coatings of various sorts in hopes that
they'll be able to develop something strong enough to be reused.
And that's not to say that they won't be able to come up with
something, just that nobody has done it yet, or, has done it and
has talked about it.
JumpCrisscross wrote 7 hours 10 min ago:
Iâm not saying we donât have work to do on materials. Iâm
narrowly pushing back on the assertion that these materials cause
the Mach 5 threshold.
jandrewrogers wrote 15 hours 8 min ago:
You could make the same argument for a lot of software tech startups.
If you develop state-of-the-art data infrastructure software, novel
data processing capabilities, or some other advanced software tech,
it is routine to have an org under the US DoD as one of the earliest
pilot customers. It is an open secret but many startups pretend like
this isn't a standard part of that kind of business. The US DoD is a
sophisticated early adopter of a lot of tech at a stage before most
commercial enterprises are willing to engage.
The average person on the street may be a bit naive about this but
the majority of deep tech startups are de facto "dual use" and none
of this should be a surprise to someone that works in deep tech.
euroderf wrote 15 hours 11 min ago:
I appreciate the sentiment, but it sounds a bit like the case of I.T.
vis-Ã -vis the NSA. As James Bamford said, one expects+assumes that
the NSA is way ahead of the state of the civilian art. They have the
budget.
Likewise this case. As an OTL civvie I'd expect that this tech under
discussion lags whatever .mil is up to. Out to launch!
axus wrote 14 hours 30 min ago:
Maybe they can catch up and end up with a more cost-effective
rocket, like SpaceX. But probably not.
credit_guy wrote 16 hours 1 min ago:
No. A lot of hypersonic stuff is partly classified. So the
journalists are left with the definition: hypersonic speed is Mach 5
and higher. Mach 5 is where the heat produced in the boundary layer
(by compression, mainly) is high enough that chemical reactions take
place and you need to account for them in your computational fluid
dynamics.
As a rule of thumb, when you hear boost-glide vehicle, the speed is
close to Mach 20. If itâs air breathing (ramjet or scramjet) the
speed is slightly higher than Mach 5, but probably less than Mach 10.
throwaway2562 wrote 16 hours 41 min ago:
Agreed, this has nothing to do with passenger flight, and the
pretense is gross.
Thin vernier -> thin veneer btw
AnarchismIsCool wrote 17 hours 33 min ago:
I'm in the industry... It's a constant psychological game. The type
of highly educated people necessary to pull off these ventures are
less interested in being part of the MIC than they used to be.
Nationalism in that crowd is thankfully much less aggressive than it
was during the cold war. As such, founders have resorted to lying
about their goals so they can expand their applicant pool for
developing the tech, then "pivot" and get acquired by Raytheon et al.
I also think to some extent there are employees who know but
semi-appreciate the cover. In a prior life, I worked on some stuff
that's, unfortunately, currently being used to murder people in the
middle east. That just doesn't make good small talk at parties.
petertodd wrote 14 hours 56 min ago:
I'd hope some of these employees are looking at what is happening
to Ukraine and reconsidering their positions. Without weapons of
your own, you're beholden to unfriendly nations with their own
weapons.
Certainly I get the sense that a lot of Ukrainians have
reconsidered their own views. There's people I know who I doubt
would have ever involved themselves in weapons development, who
have gotten into it and related things.
AnarchismIsCool wrote 9 hours 52 min ago:
What's used in Ukraine today may be killing Gazans tomorrow. I'm
not an absolutist, I'm still in the industry, but I have rules on
what I'll build for people.
shiroiushi wrote 1 hour 26 min ago:
It might be, or it might not be. Weapons can be used for good
or bad, just like most things.
Also, some weapons are less useful for bad purposes than
others: a missile-defense or air-defense system, for instance,
isn't terribly useful for bombing civilian populations, and
it's kinda hard to criticize someone for wanting to shoot down
incoming missiles. Dumb bombs, on the other hand, are great
for bombing ground targets, which could be either Russian
invaders or cities with trapped civilians.
However, if you're a SWE as many people here probably are, and
you get into the business of building weapons for war, a lot of
the stuff you'd work on probably isn't that useful for killing
Gazans. To kill lots of Gazans, you just need things like dumb
bombs, artillery shells, etc. Those things don't use software;
they've been using those weapons since WWI or before. The
"smart" weapons the expensive SWEs work on aren't so useful for
indiscriminate killing of civilian populations: they're much
more accurate, but also much more expensive, so if your goal is
just to kill civilians, they're not a very good way to spend
your money. It's much easier to just get lots of artillery
shells and shoot them in the general direction, just like
Russian troops do.
Engineers in many different industries can be blamed for
enabling awful things. Facebook engineers, for instance, I
think have a lot to answer for, for being instrumental in
destabilizing society and increasing radicalism. Engineers in
the petrochemical industry have worked to cause climate change
and pollution.
autoexecbat wrote 15 hours 53 min ago:
> less interested in being part of the MIC than they used to be
It's just TC being too low
Plenty of us are happy, even pleased, to make weapons.
buildsjets wrote 16 hours 37 min ago:
It may have hurt me financially and limited my career
opportunities, but this is one reason why I refuse to work on any
technology that requires me to have a security clearance. It's a
decision I made way back at the end of the last century and it has
served me well throughout ~25 years of aircraft development while
the world has been at continuous war, and mostly kept me out of
military programs.
Also, I took one look at the SF86 and said F that, no government
deserves that information, so I didn't get screwed in the
Department of State OPM hack like all the other suckers.
JumpCrisscross wrote 14 hours 18 min ago:
> may have hurt me financially and limited my career
Weapons doesnât pay as well as making people click ads. The
people working on this stuff are usually doing so because they
believe itâs the right thing.
shiroiushi wrote 3 hours 50 min ago:
Actually, working for DOD programs has several advantages:
1) The pay is pretty good. It's not FAANG-level pay, but it's
generally better than non-FAANG pay, without so much
competition.
2) The work-life balance is excellent, as long as it's in a
place you want to live. No 80-hour weeks, as overtime is
generally prohibited unless approved by the customer (and then
you get overtime pay). Time is tracked and paid by the
government on an hourly basis, so they don't allow overtime
unless necessary. No unpaid "exempt" overtime.
3) Generally stable employment. It's hard to find people with
a security clearance, so it's hard to get fired unless you're a
really poor performer. You probably don't have to worry about
dealing with stack ranking unlike many regular jobs.
eschneider wrote 16 hours 56 min ago:
Rest assured, founders who'll lie to their applicant pool about
that will lie to their applicant pool about anything inconvenient.
alex_young wrote 17 hours 55 min ago:
Are they targeting Mach 5? The second paragraph of TFA says "The
company's long-term ambition is to develop a commercial aircraft that
can travel at Mach 9".
They mention that goal a couple of places, and state that hypersonic
is defined as Mach 5 or more.
IntrepidWorm wrote 18 hours 5 min ago:
It does feel disingenuous, but its also nothing new. Military
research has always been the one of the primary driving forces behind
critical technology.
Commercial tech is vulnerable to all sorts of disruptions,
regulations, and setbacks. If you make something that will make
killing a whole bunch of people easier, rest assured theres a global
market for it.
nordsieck wrote 18 hours 16 min ago:
> All of these hypersonics companies are targeting mach 5 for a
reason, which is that the material science hasnt caught up yet.
My understanding is that mach ~5 is when ramjets hit their limit and
you have to transition to scramjets if you want to go faster.
MilStdJunkie wrote 17 hours 53 min ago:
That's also right around where aerodynamic forces are juuuuuuust
starting to transition to disassociation and ionization in high
flow areas, as the electrons are ripped from molecules in the air.
Probably not a coincidence, because a very ooooof zone will be the
ramjet intake, since ramjets need to slow the air to subsonic for
combustion. Lots of these high mach ramjets have amazing cooling
devices on the intake.
These RDEs are especially neat because the exhaust mass is moving
supersonically but they're very choosy about the mix in the
combustion chamber, so and air-breathing RDE will be doing some
sort of voodoo in that department. If they riddle it out they might
get a single engine that functions throughout the airspeed regime.
Havoc wrote 18 hours 50 min ago:
A fair bit of vehicles go well north of 5 already so propulsion aside
I donât think the hurdles are massive. And propulsion seems to be
what everyone is focused on
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