 Great news everyone, we're here at the US Space and Rocket Center in Huntsville, Alabama and I brought myself a friend. What's up? It's Destin from Smarter Every Day and he is going to be dropping some knowledge bombs today because behind me is the actual guidance computer from the Saturn V rocket. This is one of the engines and maybe you can enlighten us. What's the significance of the Saturn V? Oh, everybody knows that's what we use to go to the moon. This is the 50th anniversary of the Apollo moon landing and so it's a really big deal right now. So yeah, what you're going to talk about today, the instrument unit, that's what got the rocket on course to go to the moon and then the Apollo computer took over but you're talking about the rocket steering. Wow. Mark your calendar, ladies and gentlemen! Windows 7 end of life is around the corner so Smart Deploy can help you migrate to Windows 10 and manage those pesky updates. Claim your free licenses worth over $700 at smartdeploy.com slash Linus. We'll have that linked below. So what we're looking at right now is the instrument unit for the Saturn V rocket. Why is it in the shape of a ring? Well, to answer this and many other dumb questions, we've got some amazing resources today. So some of you probably don't know this but Destin from Smarter Every Day is literally a rocket scientist by training and he actually arranged someone, no offense to him, quite a bit more special as well. So the person I'm talking to right now is Luke Talley who actually worked on the flight evaluation team for this rocket when he worked at IBM back in the 60s and he was kind enough to stick around for literally hours to educate my Canadian self. Let's start by breaking down what we're looking at here. There are three main parts. Navigation, guidance and control is from about the bottom of the ring up to a little over halfway up the left side. The telemetry section is up at the top and the other side is environmental control, the umbilical plate and our power sources. So let's start with that section. It includes our main power source. Now some flights we get three of these batteries and some of them we get four but it's always the same silver zinc 5300 amp-hour 125 pound batteries. Now the technology to build lighter weight batteries didn't really exist at the time and in fact these aren't even rechargeable. You just pour the goop in about 28 hours before launch and let her rip. Now these gave the scientists about 11 hours of lifetime depending on which of the four buses was pulling power and that was all they needed. So the crew separates at about four hours and then they only really need about another hour or two of tinkering to either send the rocket around the Sun or smash it into the moon if they want to get some seismic data readings. It really depended on the purpose of the mission. Now we've got the rest of the environmental control panel or triple point device so called because it's got liquid, solid and vapor all in one spot. The main pieces are as follows. You've got your cooling duct which runs around the entire outside of the ring. This circulates conditioned air pre-launch because it's pretty hot down at the Cape. Then right before fueling it switches over to nitrogen because oxygen and rocket fuel is a pretty bad time. Then you've got coolant pumps that pump a liquid coolant to be clear not water around to the anodized aluminum cold plates that are distributed around the ring and then oh this one really got my inner cooling geek all sorts of hot and bothered. These two plates here are part of what they call the sublimator. Now if you've got up to 400 watts of heat per cooling plate and we've got 15 of them around the ring you've got to dissipate that somehow but the keen-witted among you have probably already figured out that in the vacuum of space conventional radiators don't work. There's no air to exchange the heat with. So the way the sublimator works is it has a piece of sintered metal that's exposed directly to space. This reservoir down here then is full of water and pressurized nitrogen gas with a flexible membrane in between that forces the water through the micro pores in our sintered metal. Now because these channels are so small the water freezes nearly immediately. Then because that ice gets exposed to such a low pressure environment it sublimates going directly from solid to vapor allowing it to dissipate about 9,000 watts. So this is kind of like conventional phase change cooling but space age literally. This system allows our coolant to stay between 50 and 60 degrees Fahrenheit throughout the entire mission with only the volume of water in the reservoir to fuel it. Next up power comes in from the batteries to our power distributors. These are the high current ones here that break out to sub power distributors one at the top of the ring and the other one over on the other side. Those ones go directly to components or to further lower current power distributors and the whole thing runs at 28 volts. We'll get back to those a little bit later. Now all this distribution is actually done with relays no semiconductor switching or anything like that. The cold hard truth is that semiconductors just weren't reliable enough yet. So the way that that worked was they got a signal from the black box called a switch selector. So it's the one that's right to the right of our tic-tac-toe box here and that was tied to the computer. So when it's time to fire a retro rocket or start an engine or turn on the cooling system the switch flicks. Now we're getting into navigation, guidance and control down here on the bottom of the ring. So this sphere right here in front of me is full of pressurized nitrogen gas and it feeds the gas bearing, remember we want as little friction as possible to reduce drift for what they call the guidance platform. Now it looks similar to the nitrogen ball but the insides are absolutely nothing alike. We've actually got a breakaway here that we can look at to see the main components three accelerometers and three gyroscopes. Now the fixed thing in the middle is called the stable table and before launch they release it. And then courtesy of our XY and Z axis gyros it actually maintains a fixed position so it's always in the exact same orientation it was left in no matter how the rocket is oriented or traveling around the earth. Now I said exact but that wasn't quite what I meant because for short missions this kind of system is fine but for longer ones it needs to get a little more advanced because no matter what you do even if you've got a nitrogen bearing a gyro is going to drift a little bit. So if you're doing a multi-month mission you need to build in systems to allow you to recalibrate it. Now the accelerometers which are just gyros with a weight hanging off them that torque them causing them to precess use the degree of precession as a measure of the acceleration. That gets sent to the computer which uses that data to calculate velocity which I guess brings us pretty nicely to our computer. So this small box here is the LVDC or launch vehicle digital computer. This is a truly remarkable machine. The processing modules had transistors that are actually big enough to see with the naked eye and were soldered to the compute chips built into these boards using a predecessor to ball grid array soldering. And the memory, well the 917,504 bits of working system memory was actually hand woven from copper wire and iron rings. That whole system was double redundant for memory and triple redundant for the compute. Destin and I actually go into a little bit more depth on this in the video on his channel so don't miss it. We're going to have it linked below. The second box here is the LVDA or launch vehicle data adapter. This contains a whole bunch of stuff. It's got power supplies for itself and the LVDC and a bunch of interfaces to other electronic components as well as digital to analog converters and analog to digital converters. Because thing is not everything about this system was digital. So this cylinder right here contains the analog computer from the Saturn V. This is the one that actually issues the commands to move the engines and steer the rocket. So the whole computer here, digital and analog, has no operating system. But the thing is you wouldn't want to run Windows or Android on something like this anyway. Consumer operating systems work by queuing up inputs and processing tasks and then executing them whenever it's most convenient. It basically processes them in batches. Well, this is a real-time system and it operates on a fixed two-second loop with interrupts. So if an input comes in that must be executed within a given amount of time or people could die, it needs to be able to handle that. Now, let's come back to these two black boxes again. Remember, these are our switch selectors. They've got a hundred and twelve lines going out of them that carry commands from the computer directly to components or distributors telling them to power on or power off. So again, for example, let's say the cooling vent. If we go over our temperature threshold, it sends out a command that says, hey, open it up, we need to sublimate some ice. Now, each stage of the rocket needs these and that's actually what the wiring up on the top of the ring is for. It's to link our computer here to more of these in the other stages. Although, obviously, they're not attached right now. While we're up here, this last quarter or so of the ring is for the telemetry package. So we got our transmitters, measuring racks, multiplexers, and apparently the VHF systems on here are pretty close to what Apollo 12 would have looked like. So this is not an R&D thing that might have had more telemetry stuff. This is pretty darn close to the real deal, which I guess is a pretty appropriate way for us to celebrate the Apollo 11 missions 50th anniversary. Yes, my friends, it has been that long since humans first walked on the moon, if you believe in that sort of thing. Which you should. 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It's small, easy to transport, and you can use it both inside or outdoors, although I wouldn't recommend using it in the rain, and you can check it out and buy it today at Amazon at the link in the video description. So thanks for watching, guys, and a massive extra shout-out for Destin from Smarter Every Day. Again, go check out his channel and to the US Space and Rocket Center in Huntsville, Alabama, for making this entire thing possible. They really did keep the thing open late for us to finish this video, so they're super awesome people here, and if you're ever in the area, make sure you check it out. If you guys disliked this video, you can hit that button, but if you liked it, hit like, get subscribed, or maybe consider checking out where to buy the stuff we featured. Hmm, okay. I mean, if you want to buy a rocket, like... It's a pretty big endeavor, but power to you, I guess. 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