HN Theater @HNTheaterMonth

Reminds me of a video I came across last year about about landing the space shuttle and the complexities of it all. https://www.youtube.com/watch?v=Jb4prVsXkZU

A fun little talk that describes the whole process: https://www.youtube.com/watch?v=Jb4prVsXkZU

⬐ JshWright

Aw man, I went to go find this to link it, got caught up in watching it again, and by the time I got back you had beaten me to it...

On a related note, I highly, highly recommend this entertaining and technical presentation by Bret Copeland, How to Land the Space Shuttle... From Space: https://www.youtube.com/watch?v=Jb4prVsXkZU

> I don't think the Shuttle landing was particularly problematic. They had a lot of control over the glideslope and lots and lots of runway to work with. I'm sure it's a lot more challenging than the sailplanes I fly, but I wouldn't have any major safety concerns flying on the Shuttle during landing.

Well the shuttle is a big heavy glider with little wings. One try, and down from 30,000 feet to ground in 3 minutes. Not problematic, but very special.

https://www.youtube.com/watch?v=Jb4prVsXkZU

Missed this reply, sorry! It was in this one I think towards the end: https://youtu.be/Jb4prVsXkZU

⬐ verytrivial

There's a mixture of positive confirmation and criticism being shared. eg around the sixteen minute mark:

    Pilot: Your radar's good. My radar's good.
    Commander: I agree.

Then 16:37:

    Pilot: You're going just a little bit high.
    Commander: I agree.

⬐ joekrill

This was great! I love coming across great, short talks like this that elaborate on a very interesting problem that laypeople like myself would never otherwise have even known existed.

⬐ dingaling

Accordingly Shuttle pilots and commanders are honorary members of the WWII Glider Pilots' Association. Mach 14 or 80 knots, it's the same principle!

⬐ mikeash

In the soaring community, we sometimes refer to the Shuttle as the world's highest performance motorglider. The power-off glide ratio is absolutely atrocious, though.

⬐ danbruc

What surprised me the most, the difference between being in orbit and starting to reenter is only 362 km/h but it takes a three minute burn to decelerate which I guess is a 0.5mv² thing with big m and huge v.

EDIT: My intuition was wrong, this has nothing to do with a large kinetic energy due to a large velocity.

⬐ Retric

Rocket exhaust starts with the same velocity as the shuttle which makes the v^2 part of that equation less meaningful. They use a much smaller engines to among other things add precision.

⬐ danbruc

Just realized that myself by doing the actual calculations, the Space Shuttle would need the same three minutes to come to halt from 362 km/h. In comparison, a Bugatti Veyron will do that in less than 10 seconds. So the OMS Engine are really not that powerful, at least relative to the mass of the Space Shuttle.

⬐ mikeash

The reentry burn is done with the teeny little OMS engines rather than the big main engines. If you look at the back of the Shuttle (such as https://i0.wp.com/amazingstoriesmag.com/wp-content/uploads/2...), the OMS engines are the two little ones in the upper corners. Once you're in orbit, there's usually no hurry to make changes, so you don't need much acceleration. For getting to orbit, you want to stop fighting gravity as fast as possible, so powerful engines are a must.

⬐ danbruc

Tiny is pretty relative [1]. I expected them to be more powerful and - mistakenly - thought the small acceleration is due to the large kinetic energy due to the large velocity.

[1] https://en.wikipedia.org/wiki/AJ10

⬐ mikeash

Right, rockets provide the same acceleration regardless of speed, since there's no way for the engine to "know" how fast the vehicle is moving. Acceleration is basically exhaust velocity times mass flow divided by vehicle mass.

With an 84cm diameter and weighing about 200 pounds, I'm OK calling them "tiny."

⬐ danbruc

I missed that, I only looked at the image and there it looks way more massive and larger than what the dimensions table says. Even taking into account that the image depicts an entire stage and not just the engine, 0.84 m and 100 kg is a lot less than I would have expected or guessed based on the image.

⬐ mikeash

Agreed. I first saw the image and thought wow, that really is big. Then I saw the specs.

I guess it's misleading because the engine is much closer to the camera than the background, but nothing makes that obvious. There's a tiny little person behind it, and if you don't realize the perspective difference, that would look like the engine is pretty huge.

⬐ tonylemesmer

TLDR seriously impressive stats given in an engaging, amusing, rapid fire talk by Bret Copeland, pilot

⬐ azdle

If I wanted to make a presentation like that what tools would I need to use? That was way more engaging than a powerpoint presentation. It almost seems like an animated video that pauses itself rather than a slideshow.

⬐ hugs

He lists the tools he used in the YouTube description of the video:

"All real-life photos and videos (except the last slide) were produced by NASA. Everything that looks hand-drawn was done by me on a Wacom Intuos Pro tablet in ArtRage. Animations were done in After Effects. Between the concept, outline, script, artwork, animations, rehearsals, and editing, I spent somewhere around 200 hours over two months working on it."

⬐ jedimastert

It really is just a series of animations. It's basically a time lapse of drawing. You can look at how Henry from MinutePhysics does his videos[1] (and if you like how this presentation is done, I highly recommend looking into MinutePhysics). These were probably done in something similar to flash. For open source programs, I'd probably look at Synfig[2] or Pencil2D[3].

[1] https://www.youtube.com/watch?v=GhZ3naSgJg4 [2] http://synfig.org/ [3] https://www.pencil2d.org/

⬐ satysin

That guy is a very good presenter IMHO. Amusing but not overly so, engaging and made great use of visuals.

⬐ burnbabyburn

yeah but the camera guy could have done a better job, I got motion sickness.

⬐ _archon_

I feel like the rotation clamp was too firm, and perhaps the camera could have had a mass on a torque arm to give it more angular inertia. This was SUPER distracting early in the presentation before the presenter was scaled down.

⬐ funnyfacts365

The video description says it was the autofocus...

⬐ funnyfacts365

You should complain to Steve.

⬐ creo

IMHO he is too aggressive ... i cant focus on what he talks about, most of the presentation.

⬐ hi2thegovna

Very informative! I especially liked the animations and comedic delivery. Both of these methods really made the information relatable and memorable. Excellent stuff. Thanks for the post.