Apollo: The Alignment Optical Telescope

Bill describes the Alignment Optical Telescope used in the Lunar Module on the Apollo missions to the moon. This telescope took star sightings which were used to align the Module's guidance system. Bill shows how the telescope used an Archimedes spiral inscribed on its eyepiece to replace the heavy motors, worm gears, and rigid tracks used in a traditional sextant -- this shaved weight from the Lunar Module and allowed it to carry more fuel.
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If you are interested in mechanical computers you'll likely enjoy his series on Albert Michelson's Harmonic Analyzer -- a 19th century machine that calculates Fourier transforms:
• Albert Michelson's Har...

[@RealEngineering]

Very nice Bill and Wyatt!

[@omsingharjit]

👌

[@PracticalEngineeringChannel]

One of my favorites. Awesome work Bill.

[@AakashKalaria]

Hey, I subscribed to your channel around 6 hours back after I saw space elevator video. Great Stuff!

[@joanalbertmirallespascual3606]

Hello over here Practical Engineering!

[@brianwyters2150]

Some of his other stuff is awesome. I like his animated radio talks, which are very information dense. And a message to you. Your videos are getting more and more specific and not quite as awesome as your older videos. The MSE video was awesome and you didn't use anything fancy like equations you use now. I miss the old days.

[@truthseeker8894]

Brian Wyters He is only deceiving you honest people with these space junk stories. Research the Apollo program yourself and find out that everything is fabricated and filmed on earth.

[@cristianjeremy880]

Pro trick : you can watch series on Flixzone. Me and my gf have been using it for watching all kinds of movies recently.

[@PanzarMetal]

Amazing! I think there's a point at which when a design is so simple yet elegant it becomes pure beauty!

[@FlyingJetpack1]

That's mindblowingly simple for such a complex problem! It's extremely elegant, using the spin as measurement of distance to not clutter the screen is just brilliant!

[@seigeengine]

It also means you can just rotate it to stop obscuring anything it does.

[@Oldbmwr100rs]

The B/W video camera RCA developed was restricted to very little weight and power, something like only 17 watts. In the end the entire system was engineered to operate at a much lower resolution to the point that everything was weighed down on the receiving end on earth. Only a few actual receivers for that format were made. Sadly the original recorded footage from that system is in poor shape.

[@FosterZygote]

The Lunar Surface Camera used during the Apollo 11 landing was actually made by Westinghouse. RCA made the Ground Command Color Television used on the J Missions. It actually operated at 6.25 Watts. Here's a PDF with some fascinating information about most every aspect of the Apollo television broadcasts. www.hq.nasa.gov/alsj/ApolloTV-Acrobat5.pdf

[@timearly5226]

Let's give it up to the old slide rule generation. Woop! Woop!

[@satyris410]

I swore out loud sat by myself in my room when he mentioned the archimedes spiral. Absolute - - - genius

[@kokofan50]

This is great example of how space forces the rethinking of even the smallest things.

[@joanalbertmirallespascual3606]

As an aerospace engineer this is candy for my brain. Great to know that you are not dead!! It was a long time.

[@crazymuthaphukr]

where do you work

[@joanalbertmirallespascual3606]

looking for a job right now

[@casualbird7671]

Hope you found one. A reason why I eventually decided against Aerospace as a career was because of poor job outlook >v

[@RichardKinch]

Another human factor in the optical engineering: the eye is more precise at lining up two marks (such as star versus a reticle scribe) than it is at interpolating measured positions against a graduated ruler. In the case of a star being "eclipsed" by the reticle line, further precision is available by fine-tuning against the minimum apparent intensity in addition to the position. (The reticle line width would be printed at a width approximately that of the star point image, so the star would disappear when the two were precisely aligned.) So the Archimedes spiral reads both position and intensity of the star image, and the spiral's slope acting through the radial vernier precisely amplifies these scales by another factor of pi. And no atmospheric distortion or scintillation in this environment. The mechanism implements a triple compound stack of verniers with one moving part! Brilliant design!

[@NickFerry]

so much fun to watch Bill!

[@mako88sb]

Great job explaining the nav system. Just finished reading Frank Borman's book and it was pretty amazing to find out how close Jim Lovell was able to figure out their location compared to what the computer on Earth was indicating where they should be. From 300,000 kilometers distance traveled during 2 days, they where within 500 meters.

[@eddievhfan1984]

Very good video. :) I actually help contribute to a simulation project for the Apollo program using the Orbiter space simulator (NASSP), and this is rather spot on. However, when the LEM was in free flight, they didn't use the spiral method, as it would require more stabilization during the sighting than the LEM could provide (at least not without wasting fuel). So instead, they used 2 star sightings, like the Command Module did, but placed the LEM in a rotation, and used the time when the stars crossed the X and Y axes of the AOT's crosshairs to provide the star angles. Repeat for the second star, and you got your alignment info.

[@DJJekyll]

Mr. Hammack, the way you speak about your topics is fantasic. You've just become one of my favorite teachers.

[@Eurofilth]

I watched a video in which a retired Air Force pilot that flew the SR-71 Blackbird gave a run down of how everything worked inside the plane and they also used celestial navigation. He only explained the basics of it. I now understand all of it. Awesome video!

[@mako88sb]

Must be the one with Richard Graham. Great video and really showcases just how incredible a plane it was. I got one of his latest book after watching that video and highly recommend it. Titled " The Complete Book of the SR-71 Blackbird:"

[@JonJwhittaker]

What a fantastic video. Thank you for sharing this amazing knowledge, having graduated in mechanical engineering only a month ago, I can truly appreciate and adore this elegant solution

[@pauloboczky1470]

I am amazed on a daily basis with the design of Apollo. Another simple yet brilliant design was the electronics module in the Lunar Rover. It was encased in wax! When it heated up it melted the wax to dissipate heat. When it cooled off the wax solidified again to insulate it!!! Simple but ingenious!!

[@mako88sb]

Well said. Same can be said for the ice sublimating in a vacuum system used for cooling the LM and astronaut space suits via the PLSS. Also used to cool the Saturn V instrumentation ring once it reached high enough altitude.

[@CT-pi2gl]

It's incredible to think of all the human beings in all the eras of history, even Archemedes thousands of years ago, who contributed to this monumental achievement.

[@jackflash6377]

I have great respect for the engineers involved in the Space program in those days. Pure genius, dedication and hard work. Outstanding video. Thanks

[@satyris410]

I swore out loud sat by myself in my room when he mentioned the archimedes spiral. Absolute - - - genius

[@mirrorblue100]

It is humbling to consider how inspired the engineering on that project was given the - by today's standards - anemic computer power they had. Thanks for another great program.

[@jonathanfanning9558]

What a beautifully, elegant solution of an Archimedes spiral that yield such precision.

[@SuperVt100]

Awesome video on the engineering that went into the Apollo space program. *Engineering* One of the hallmarks of the Apollo space program was they had five teams on each engineering problem. The one that came up with the best solution was chosen. You might say that was a little bit of institutional competition and capitalism. *Inspections* They also checked and rechecked everything. Everything was inspected. I don't think any program has been so engineered as the Apollo space program. That's what I heard.

[@Tyrog]

Great video as always! Fascinating how technical and weight restrictions foster amazing engineering!

[@SSJ0016]

I love that you make interesting 5 minute videos with zero bullshit about really complex systems . Sometimes it's complicated stuff, but not always, but you do always point out something interesting, whatever it is you're talking about. Even if it's just a stupid toaster made in the 90s.

[@stuartgarfatth1448]

As soon as I saw the 'Apollo : the alignment optical telescope, I HAD to sign up!. Absolutely absorbing, very well explained and presented, a must for everyone with an enquiring. Many thanks Bill.

[@Twitchi]

Always amazes me that such complex operations can be carried out with a few simple steps.. thanks for going into the details.. loved it :D

[@google_was_my_idea]

Been a long while, back finally, hope to see your videos more often, cheers and nice video btw :)

[@MariuszGruszkajamaniek]

Amazing video as always! I'm in college right now studying automatic control and robotics, and every time I watch your videos, they give me an extra push and remind how much more I must learn and what can be achieved :) Thank you.

[@jessesanchez9998]

nice to see you back. love your vids

[@Paethgoat]

Bill, you have one of the most soothing and hypnotic voices I have ever had the pleasure of listening to. I hope your work continues for quite some time.

[@filipbunalti]

Brilliant video to mark the return. Great work, Bill!!

[@panwarhappy9368]

Wow..... That's the Wonder of ancient engineering... The arcemedies spiral

[@kevintripp5331]

I really enjoyed the video. My grandfather Robert Tripp Sr. was the optical engineer who designed the Alignment Optical Telescope for Kollsman in NY.

[@lightandtheheat]

This is wonderful. Miss you, Bill. Please make more videos!

[@Gammaduster]

Super neat and concise as always. I'd be the most delighted if you were to make an entire Apollo series !

[@ltd500]

Love it Bill! It's amazing that we even went to the moon and back on 1960's technology! A credit to engineer's everywhere!

[@ardoin_337]

You're back and better than ever man. Thanks for the vids.

[@shadroth]

Great to see you back! Keep up the good work!

[@StayUpStrack]

This is awesome!! Thank you so much for putting these together.

[@nithinmohan3140]

Use of Archimedes spiral is just mind blowing.... Great video and great explanation.....

[@snavarro228]

This was absolutely amazing. Thank you for posting...

[@weirdwurstLP]

So happy to see a new video from you!

[@justinschnepf]

why are your videos so awesome?!?! I get excited every time I see a new video has been posted.

[@serhancinar5218]

Great video, thanks for a detailed explanation on the Archimedes Spiral.

[@EverettMcConnaughey]

This was very informative. I enjoy your analysis and presentation methods.

[@sarcasmo57]

Another great video! Thanks Bill.

[@raguaviva]

oooooooooooooh fantastic!!! I few days ago I was reading about Achimedes and now you tell me this fantastic story!

[@daniellassander]

Awesome video, so well done and well researched, and of course presented in a very very good way!

[@rockerlkj]

I've missed you, Engineer Guy. Never leave me again.

[@MaxLenormand]

I have just discovered your channel, this is one of the best engineering channels out there! :D Please do more on space and/or aeronautics, on subjects like this, that we do not hear about, but that are still so interesting! :-)

[@mimsnshine]

As usual an incredible and detailed explanation..thank you Bill 💝💝💝💝💝

[@JoelShapiro]

Great video! One of my favorites to date!

[@kayyyp4939]

wow such attention to detail. Amazing!

[@coopdenn1738]

I don't understand any of this but he's so fascinating to watch and his voice is so relaxing so I watch it anyways

[@peachtrees27]

Thank you for putting this together.

[@frederiklauferts]

Great editing!

[@engineerguyvideo]

wyatt did that!

[@waswestkan]

I enjoy learning of details like this.

[@spikeman4pres]

That was truly amazing , glad to see your still alive ;D

[@XFanmarX]

This is insanely well-edited. I'm hooked!

[@balls2balls]

So glad to see you back Bill! Can't wait for more!

[@error.418]

Finally, a new video! Thank you!

[@aagguujjaa]

Amazing, thank you for the quality video. Looking forward to the lecture series.

[@Cavush]

This channel should have millions of subscribers. Your videos are simply brilliant !

[@AnalyticalReckoner]

Great video like always! I wish I could watch you explain everything!

[@blackbear92201]

Awesome video - thanks for posting!

[@hyperdrivepics]

Genius! I don't know how they would've thought of the spiral.

[@Zerepzerreitug]

If the movie _Apollo 13_ is any indication, my guess is that it took a room of engineers with pen protectors, slide rulers, and tons of coffee xD

[@mako88sb]

Yes, quite the amazing effort. I remember reading Tom Kelly's book about the incident were Kelly mentions he went straight to the Grumman facility and found others already arriving there. Nobody had to be called in, they just knew they might be needed so headed over right away. Not sure how it was for North American Aviation but I imagine it was a similar scene.

[@raoulcruz4404]

You got that right. The SR-71 was built with slide rules. "slip sticks".

[@Bnio]

In "Apollo" by Murray and Cox, there is a quick story about a Grumman engineer pulled over for speeding, and when he explains to the cop that he's trying to get to the Bethpage plant to help with Apollo 13, the cop waves the ticket, and gives him a police escort, sirens and all.

[@promerops]

I started my career using a slide rule - the big advantage is the awareness of magnitude that is necessary when using one.

[@panulli4]

Nice to have you back!

[@DominikRoszkowski]

Very clever idea presented in this wonderful video. Thanks a lot!

[@jerhunt4561]

Absolutely fascinating.

[@pvdashcams3402]

Thanks again for quality content.

[@NewMetallica]

Bill is back! Awesome video as always!

[@MrDavidCrane]

Thanks for your wonderful videos! Keep of the good work!

[@AgentMidnight]

Another masterpiece, Bill!

[@AV1461]

I can only imagine the imensitude of awesome details associated with the lunar missons. So many problems to solve and so many constraints. I'm an engineer graduating in my masters and I must know every detail like this! Videos like this are precious. The engineerguy is a really awesome channel!

[@mako88sb]

Probably my favorite episode of "From the Earth to the Moon" is the "Spider" episode. Fascinating to see the evolution of design process with the elimination of the seats and huge reduction in weight by being able to go with much smaller windows. Not sure how much those seats would of weighed but I'm thinking those along with the reduced glass area might of cut the weight by about 800. Pretty significant as Kelly's book mentions that every lb of weight reduction meant 3 less lbs of combined ascent/descent rocket fuel required. If you haven't read Tom Kelly's book, I highly recommend it. The chapter titled "Problems, Problems" is just a great read. The ascent engine instability issues where especially worrisome. Here's a quote from the book: "Frequently the LM ascent engine made the notorious "show stoppers" list as a problem that could stop the enormous nationwide Apollo program dead in it's tracks." They did tests to make sure any oscillations caused by combustion instability would eventually dampen out. That test involves detonating a bomb(more like a blasting cap) inside the nozzle during a test firing to make sure spontaneous instability wouldn't lead to an engine explosion. The troublesome ascent stage only received approval after passing 53 consecutive bomb tests. Btw, this bomb testing method , was developed after 3 of the expensive F-1 engines for the Saturn S-1C where destroyed during testing.

[@denubisx]

That was an excellent explanation. Interesting and very well done.

[@scyther1141]

Glad you're back. I wish you made videos full time :c

[@lumirkaras]

This is so cool. Thank you for this interesting fact!

[@Leander_]

Great video as always!

[@PRRGG1]

Wonderful video! I had always wondered how the angle was calculated. Thanks .

[@archiggy89]

You are an incredible teacher!

[@Ravenall]

I like this guys voice. easy to listen to.

[@jakob681]

these videos are awesome and deserve more views !

[@jackhong1981]

I have watched a few times but I still can't comprehend most of the content. No wonder they call it rocket science.

[@AnantMall]

How you have any less than a million subscribers is beyond my understanding !!!

[@DC_ABC_123]

This is perhaps one of the coolest things I've ever learned.

[@acrutix]

You are awesome bill. I appreciate your content. Very enlightening.

[@BrekMartin]

Great to see you back :)

[@VoltzerOfficial]

really neat video as always!

[@TheJaredtheJaredlong]

I hope whoever came up with that idea got a raise or something.

[@hexadecimil]

i got a tingling feeling at the end of this video when i fully understood the elegance of the solution.

[@Heeby-Jeebies]

This is brilliant! I knew the module required a lot of careful thought, but I never knew about this!

[@AeonPrime92]

Good to see you again Bill :)

[@athief]

Very nice video, very clever design, love it!

[@GregMcCarthyUK]

great video. welcome back.

[@JarinUdom]

This is my new favorite channel

[@eleventhphotograph]

Very informative! Would love to see more on the Apollo missions.

[@TomislavKolaric]

amazing video, i love your work

[@samsignorelli]

Since you were naming the astronauts...the one with the red helmet doing the stand-up EVA at 0:58 is David Scott. This shot was from Apollo 9 -- the first test flight of the LM in space and independent of the CSM. Scott was the Command Module Pilot on that mission. He would later walk on the Moon as commander of Apollo 15.n

[@davidthegreen]

Love your work.

[@kevito111]

Beautiful video, Thanks

[@mattlocke4680]

We love your work

[@heXan]

Beatuiful! The video and the engineering! ^^