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A working flight simulator, no computers necessary

Tom Scott · Youtube · 196 HN points · 0 HN comments
HN Theater has aggregated all Hacker News stories and comments that mention Tom Scott's video "A working flight simulator, no computers necessary".
Youtube Summary
There are only a few working Link Trainers left in the world: but before microprocessors, before display screnes, half a million pilots learned the basics of instrument flying inside one. More:

Edited by Michelle Martin,

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Jul 05, 2022 · 196 points, 45 comments · submitted by sohkamyung
My father used to work at Link (Singer at the time, technically) and later CAE-Link. His office had a 'Blue Box' trainer in the lobby. It was supposed to be a museum piece, but his management was known to look the other way when employees brought their kids in after hours or on the weekend to sit in the trainer. Kid 'ride alongs' in the motion base simulators on site weren't officially condoned, but happened a lot too.

Didn't realize how lucky I was to have such experiences until much later in life.

Just to clarify, this is an instrument flight training device, not a primary trainer. The benefit of moving the trainer as pilot moves controls is to recreate similar illusions to the ones found when flying in instrument conditions and teach the pilot to rely on instruments instead of the pilot’s senses.
Didn’t Tom say the instruments are non functional. I’m confused, how is this useful at all besides spinning around.
They used to be functional when it was actually used as a trainer.
Ah that makes sense.
For FAA pilots, I can heartily recommend ATOP for an airline 2-day intro, including sim time.

I did the 737 course when it was at United and it was some of the best fun/interest per dollar and hour. (no affiliation other than long-ago satisfied customer)

Oh wow, this looks amazing. Do you need to be a licensed pilot to participate?
Unfortunately, yes.

> The ATOP offers any FAA certificated U.S. pilot with an interest in the airlines...

I can also recommend that, but it’s admittedly not something to just do on a whim some weekend sometime… :)

As a schoolkid in 1970's Lubbock, TX we got to visit Reese AFB where they did jet training on the T37 and T38. The simulator room had a set of enormous landscape dioramas, my recollection is that they were something like 20 feet by 20 feet. The simulator would "fly" a camera over the diorama. There was a cockpit on hydraulic actuators. I don't remember what the display looked like (or even if I got to see it), but I do remember those huge dioramas and thinking how funny it would be if you "crashed" into a spiderweb on the simulator :)
The Lunar Module simulator used by Apollo astronauts used a similar technique.
Thread of pilots reminiscing about these simulators including common japes of putting spiders or kids' toys on the landscape. Don't miss post #4 for a cool video:

My small town carnival in Wachapreague, Virginia, had a ride in the 1980s called (most likely from research and my fading memory) the Fly-o-Plane in which you climbed inside a similar metal can on arms and rotate around an axis while having the ability to tilt the 'wings' to mostly change the roll of the plane. If you were pretty aggressive you could fly basically upside down the whole ride. I LOVED it! There were certainly quite a few of the planes that ended up dripping vomit. I was quite sad to visit that fairground this year with my kids to see the planes no longer exist.

Here is a video of a similar ride in Georgia. Is it still there?

Atlas Obscura talks about several of these type rides over the years in amusement parks:

I've been playing a lot of flight simulator 2020 lately. Besides it looking absolutely amazing with photo realistic terrain, scenery, and water it is very detailed and accurate.

So much so, that I would feel comfortable if in a pinch, attempting landing a handful of the planes I have been flying in FS. Full disclosure, I also do have around 4 hours logged with an instructor as well so it's not like I have zero real-life flight experience.

I have my first hour booked Thursday lunch (I took a few hours lessons in school as part of the Air Cadets but lost the log book). I've also started playing Flight Simulator. All I've managed to do there is wreck a few F-18s :( What planes are you flying? Something more realistic to your lessons?
An analog computer is still a computer :)
Not in the modern sense of a programmable device that can straightforwardly solve logic problems.
Is this really that different from a niche ASIC board or something?
All computers compute but not all computers are general purpose.
I couldn’t tell from the video, what do you see inside the link? Just the gauges? Is the idea to simulate flying in total darkness or cloud cover?
Yes, this kind of training is for flying by instrument, which is quite hard. That's why they needed simulators.

When I was taking flying lessons, for one session the instructor had me wear a visor so I could only see the instrument panel for a while, and then try holding a course. I believe it's mostly just to demonstrate that you shouldn't try it until you're trained for it.

When it was working, it apparently had your typical six-pack of steam gauges.

The one that the Youtuber was looking at had all the gauges removed because they had radium paint; honestly, without the gauges it's really only a good demonstrator of how it's completely futile to try to fly a plane without visual cues or instruments due to somatogyral and somatogravic illusions of the vestibular system.

Silly question, but is radium paint that bad? Like you wouldn't want to eat it obviously, or wear it on your arm your whole life, but would occasional exposure be an issue compared to other sources?

I could only find this [0], but I'm not sure how to find information about radium paint.


You may be interested in this story which does involve people literally eating radium.

> The factory manufactured glow-in-the-dark watch dials that used radium to make them luminous.

> The women would dip their brushes into radium, lick the tip of the brushes to give them a precise point, and paint the numbers onto the dial. That direct contact and exposure led to many women dying from radium poisoning.

Thanks for that I remember reading that story and seeing the pictures, so I might leave that link unclicked for today
I don't think sealed radium dials would be a big deal as long as they remained intact, but I can see how you wouldn't necessarily want to have them in a publicly accessible place where the glass might accidentally be broken etc.
Amateur watchmaker here. Its half life is ~1600 years, so it's still plenty hot. Hot enough, in fact, to burn out the phosphor in the radium paint, so it stops glowing, but flakes off as radium dust as the binders in the paint break down. Radium produces mostly alpha radiation, which is blocked by glass or your skin, but if you inhale or ingest the particles, it's not good for you, as the alpha particles will go directly into the surrounding tissue. The people exposed to the worst of it would be the ones stripping the radium paint off the dials and refinishing them, as that generates a lot of dust that you might inhale.
A real life horologist! Ok so primarily ingestion is the concern, but if it's sealed in epoxy or something it's not immediately dangerous.

While I have you here - what do you think of Clickspring? Do you have any cool escapement pictures?

I'm sad, nobody still made replica replacements for instruments. I think this is very possible task, even not hard with current tech.
There's one of these in Cleveland at the Air & Space Museum
Why it spins continually?
Because the pilot is in a graveyard spiral but feels he is going straight. With no instruments and no outside visibility, that's what happens.[1]


I gave my friend an hour in the link trainer for his retirement. He tried to take off, enter the approach, and land. 45 minutes later he failed. When he stepped out of the trainer he had sweat so much he looked like he took a shower.

I got a turn after him. Just a simple task, take off, enter the approach, and "follow the needles" back to the runway. I managed to get it down on the grass parallel to the runway. I also looked like I had taken a shower.

The wild part is that (a) it feels REAL and (b) they added weather while I was flying.

I want one of these at home.

How do you "follow the needles" when the machine has no screens and I guess all you have is communication is with a person outside the machine who tells you where you are? Normally, you'd have a visual on the runway when you land, so I can understand its much more difficult when you're sitting in a dark box with someone just instructing you what to do. Flying by instrument is really really hard, especially if you have zero training.

> they added weather while I was flying

This I don't understand, like they spray water on you when you're in the cockpit or how was this implemented?

Adding weather is likely extra wind and reduced "visual" to the ground
> reduced "visual" to the ground

But there is no "visual" in the first place in the "Link Trainer".

You mean that the gauges start showing false/modified values than what they really should? Or that the outside instructor fuddles with the instructions they give you?

The wind slows or speeds up the aircraft, requiring power adjustments, and changes its ground track, requiring course adjustments. In weather, the wind may be varying as you fly, requiring constant adjustments. When flying by instruments you have to do those adjustments based on what you see on the instruments as there is no outside reference.
Tom said all of the gauges are non-functional. That would seem impossible. Not sure what the point is without them except as a mechanical curiosity.
Yes, it's sadly quite pointless without.
At another point, one of the others mentioned that the original gauges had to be removed because of radium in the dials. It's a bit sad they couldn't have been replaced with non-radioactive replicas.
There's more than one surviving Link Trainer in the world:

The gauges on that particular one have been removed; on others, they may have been replaced, or the radioactive paint stripped off, or the dose deemed low enough to not be worth worrying about.

Does the blue box have any ventilation? The video makes it look like a hot box.
The sweat is because it’s an enclosed box with no ventilation right? Why else would you be sweating, you’re not physically strained too much in it.
I've sweated in a cold AC room.

Btw, sweating when it's cold somehow feels much worse.

Nerves & stress.

I had the opportunity to spend a couple of hours in a full-motion T-38[0] trainer while in the Air Force (a roommate was there TDY making some repairs and needed a hand testing them). The motion makes you feel like you're really in a plane. I made three approaches - the most "successful" of them had me run off the runway into the grass and slide sideways to a stop (landing a jet is no joke). While the Link Trainer is obviously primitive compared to the one I was in, the sensations are just as real, as is the stress of trying your hardest not to crash.

While I will give the Navy grief over nearly everything :) I have the utmost respect for carrier pilots.


Your comment made me think of this story:

A 64-year-old French pensioner was recently peer pressured into flying in a fighter jet to celebrate his retirement. The man was so nervous he reached out during the flight and accidentally ejected himself mid-flight, a report from IFL Science reveals. ...

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