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Q-learning is not yet scalable

https://seohong.me/blog/q-learning-is-not-yet-scalable/
86•jxmorris12•5h ago•16 comments

Infinite Grid of Resistors

https://www.mathpages.com/home/kmath668/kmath668.htm
134•niklasbuschmann•8h ago•55 comments

I have reimplemented Stable Diffusion 3.5 from scratch in pure PyTorch

https://github.com/yousef-rafat/miniDiffusion
385•yousef_g•16h ago•69 comments

Breaking My Security Assignments

https://www.akpain.net/blog/breaking-secnet-assignments/
20•surprisetalk•2d ago•0 comments

AMD's AI Future Is Rack Scale 'Helios'

https://morethanmoore.substack.com/p/amds-ai-future-is-rack-scale-helios
56•rbanffy•9h ago•28 comments

Have a damaged painting? Restore it in just hours with an AI-generated “mask”

https://news.mit.edu/2025/restoring-damaged-paintings-using-ai-generated-mask-0611
51•WithinReason•2d ago•30 comments

Iconic icons to showcase your skills

https://github.com/YuheshPandian/ICONIC
19•Yuhesh•2d ago•6 comments

Inside the Apollo “8-Ball” FDAI (Flight Director / Attitude Indicator)

https://www.righto.com/2025/06/inside-apollo-fdai.html
138•zdw•15h ago•25 comments

Chicken Eyeglasses

https://en.wikipedia.org/wiki/Chicken_eyeglasses
84•thomassmith65•4d ago•23 comments

Solar Orbiter gets world-first views of the Sun's poles

https://www.esa.int/Science_Exploration/Space_Science/Solar_Orbiter/Solar_Orbiter_gets_world-first_views_of_the_Sun_s_poles
209•sohkamyung•3d ago•27 comments

Wrong ways to use the databases, when the pendulum swung too far

https://www.luu.io/posts/2025-database-pendulum
62•luuio•2d ago•32 comments

Waymo rides cost more than Uber or Lyft and people are paying anyway

https://techcrunch.com/2025/06/12/waymo-rides-cost-more-than-uber-or-lyft-and-people-are-paying-anyway/
317•achristmascarl•2d ago•557 comments

Dance Captcha

https://dance-captcha.vercel.app/
12•edwinarbus•2d ago•4 comments

Last fifty years of integer linear programming: Recent practical advances

https://inria.hal.science/hal-04776866v1
187•teleforce•1d ago•55 comments

Unsupervised Elicitation of Language Models

https://arxiv.org/abs/2506.10139
125•kordlessagain•18h ago•16 comments

Fixing the mechanics of my bullet chess

https://jacobbrazeal.wordpress.com/2025/06/14/fixing-the-mechanics-of-my-bullet-chess/
27•tibbar•7h ago•16 comments

Bioprospectors mine microbial genomes for antibiotic gold

https://cen.acs.org/pharmaceuticals/drug-discovery/Bioprospectors-mine-microbial-genomes-antibiotic/103/web/2025/06
5•bryanrasmussen•3d ago•0 comments

Cray versus Raspberry Pi

https://www.aardvark.co.nz/daily/2025/0611.shtml
82•flyingkiwi44•4d ago•59 comments

Seven replies to the viral Apple reasoning paper and why they fall short

https://garymarcus.substack.com/p/seven-replies-to-the-viral-apple
263•spwestwood•10h ago•199 comments

SIMD-friendly algorithms for substring searching (2016)

http://0x80.pl/notesen/2016-11-28-simd-strfind.html
207•Rendello•1d ago•31 comments

Endometriosis is an interesting disease

https://www.owlposting.com/p/endometriosis-is-an-incredibly-interesting
336•crescit_eundo•1d ago•232 comments

The Many Sides of Erik Satie

https://thereader.mitpress.mit.edu/the-many-sides-of-erik-satie/
141•anarbadalov•6d ago•31 comments

How to Build Conscious Machines

https://osf.io/preprints/thesiscommons/wehmg_v1
65•hardmaru•19h ago•68 comments

Clinical knowledge in LLMs does not translate to human interactions

https://arxiv.org/pdf/2504.18919
72•insistent•8h ago•32 comments

Sperm are very different from all other cells

https://www.bbc.com/future/article/20250613-untangling-the-mysteries-of-what-we-dont-know-about-sperm
32•viewtransform•5h ago•21 comments

TimeGuessr

https://timeguessr.com/
278•stefanpie•5d ago•58 comments

Peano arithmetic is enough, because Peano arithmetic encodes computation

https://math.stackexchange.com/a/5075056/6708
227•btilly•1d ago•113 comments

We investigated Amsterdam's attempt to build a 'fair' fraud detection model

https://www.lighthousereports.com/methodology/amsterdam-fairness/
61•troelsSteegin•2d ago•49 comments

Debunking HDR [video]

https://yedlin.net/DebunkingHDR/index.html
75•plastic3169•3d ago•43 comments

Large language models often know when they are being evaluated

https://arxiv.org/abs/2505.23836
44•jonbaer•4h ago•56 comments
Open in hackernews

Inside the Apollo “8-Ball” FDAI (Flight Director / Attitude Indicator)

https://www.righto.com/2025/06/inside-apollo-fdai.html
138•zdw•15h ago

Comments

kens•14h ago
Author here for your Apollo questions :-)
johng•14h ago
I mainly remember this because he refers to it as the 'frappin 8 ball' in the Apollo 13 movie, if my memory serves.
mcpeepants•14h ago
same here, he sure does
kens•13h ago
Yes, in the movie, Lovell says "What's the frappin' attitude?" as the 8-ball rolls out of control. The actual Apollo 13 transcript has nothing like that, interestingly enough.

Links: https://archive.org/details/apollo1319959231994/page/n92/mod... https://www.nasa.gov/wp-content/uploads/static/history/alsj/...

rbanffy•14h ago
I remember a similar thing from the, IIRC, F-104.
_dwt•14h ago
Great article. I'd never thought about a spacecraft ADI having a third axis. Sadly, a nitpick - Bill Lear's F-5 autopilot was not, as far as I can tell, in any way connected to the Northrop F-5 fighter jet.
kens•13h ago
Thanks. You are correct about the F-5 autopilot, so I fixed that. It turns out that it was used in planes such as the C-47, C-60, C-45, and B-26, but is unrelated to the F-5.
garaetjjte•9h ago
>The Command Module for Apollo used a completely different FDAI (flight director-attitude indicator) that was built by Honeywell.

That's surprising. Was there any requirement that necessitated them to be different parts, or it's just because different suppliers were chosen by Grumman/North American?

kens•7h ago
It's probably a combination of different suppliers being chosen, and everyone wanted a piece of the pie. But it's annoying when I figure out how something works in the Lunar Module and then discover that the Command Module is completely different. Not to mention that the Saturn V is a whole different world.
jschveibinz•14h ago
Back in the day, this would be have been a good homework assignment for an EE analog controls class.
chiph•14h ago
kens - Are the collectors of the output transistors on the amplifier boards connected to the metal can? I can see from the photo that the heatsinks don't touch (there's a gap between them for the capacitors). Did they use nylon screws to prevent an electrical path through the frame?
kens•13h ago
Unfortunately, I don't have the FDAI handy to check this.
CamperBob2•12h ago
For TO-5 bipolars, it was common for the collector to be connected to the case. I wouldn't say that's universally true but I don't recall any exceptions off the top of my head.
WillAdams•14h ago
This was actually mentioned in a recent talk by Freya Holmér --- I believe this one:

https://www.youtube.com/watch?v=hUlvxaQBW78

wafflemaker•12h ago
That's a 'kunst' of UI (a gem?). One look and you instantly know the orientation of your craft.

As an amateur astro-pilot (1000h in KSP and 200+ in Flight of Nova, both flight simulators with realistic orbital mechanics) I'd like to say that in modern cockpit of the fusion propelled ships in FoA, the one thing I'm missing from Apollo-style flight instruments of KSP is the Nav-Ball.

The jet-fighter-like "ladder" style attitude meter can't be read with just one look. You need to focus to see the numbers next to the ladder steps. And then another look at the compass for a full reading. 3s of focus (away from controlling the ship) vs. 0.5 (that your subconscious has most likely already interialized).

To put that 3s into perspective, according to ship readings, Apollo 11 had <20s fuel left when it touched down on the moon.

johnsutor•12h ago
Brings me back to playing Kerbal Space Program
timewizard•11h ago
I wonder if that simulator was OV-095 at SAIL.

https://spaceflightblunders.wordpress.com/2017/03/31/ov-095-...

EDIT: Ah. It almost certainly was:

https://www.superstock.com/asset/oct-astronauts-frederick-ri...

kens•11h ago
There are many different Shuttle simulators. The simulator photo in my post is one of the Shuttle Mission Simulators (SMS), now at Stafford Museum in Oklahoma. The Shuttle Avionics Integration Laboratory (SAIL) is a different simulator for avionics testing (rather than astronaut training) and is currently in Houston.
jart•10h ago
Ken once again proves he's one of the greatest publishers on Hacker News.
dmd•10h ago
The strong impression I always get from the entire Apollo program is "they didn't know it couldn't be done at the level of technology available, so they did it anyway".
SoftTalker•2h ago
That and they essentially had unlimited money.
jsrcout•9h ago

  > 3. The FDAI's signals are more complicated than I described above. Among
  > other things, the IMU's gimbal angles use a different coordinate system from
  > the FDAI, so an electromechanical unit called GASTA (Gimbal Angle Sequence
  > Transformation Assembly) used resolvers and motors to convert the
  > coordinates.
I'm so glad I work in software.
userbinator•9h ago
1960s technology, designed and made in the USA. It seems that people back then were far more clever at making do with what they had.
Animats•3h ago
We had an article on HN last year about a similar Soviet era device. It was a globe that showed the position of the spacecraft relative to the earth.
kens•1h ago
The Soviet Globus is similar in some ways, but also has some major differences. As you mentioned, the ball shows the spacecraft's position over the earth, rather than showing the spacecraft's orientation in space, so the ball looks like a globe with landmasses and everything. The ball rotates along two axes, not three. Moreover, the Globus doesn't have any external inputs; it rotates the ball according to a preset track, regardless of where you actually are.

My three articles on the Globus had the following HN discussions: https://news.ycombinator.com/item?id=34468212 https://news.ycombinator.com/item?id=35311300 https://news.ycombinator.com/item?id=35038710