It has the actual flight plan for Apollo 13, and it has a lot of other things in it.
Today on Smarter Every Day, we’re in the middle of a series about going back to the moon. We’ve looked at how the Apollo astronauts trained, the Lunar Lander Test Vehicle, and even NASA’s early ventures into autonomously landing on the moon. Now it’s time to go deeper and understand the entire Saturn V rocket. Wernher von Braun said, “as the IU goes, so goes the Saturn.” That’s why we’re talking to Luke Talley, one of the original IBM engineers over the instrument unit. Before we do that, let’s take a look at the person behind the engineer.
November 10th, 1944, a young sailor from Alabama was killed in the Pacific Theater in World War Two. His three year old son, Luke Talley, was extremely curious and loved making Crystal radios. Thanks to the help of his community, he was able to pursue his passion and go to the University of Alabama to study electrical engineering. After that, he went to IBM, where he became an award winning engineer on the Apollo program. He was even invited to attend the launch of Apollo 13 at Cape Can Kennedy on April 11th.
Now we get to learn from Luke Talley, the best person to explain the Saturn V rocket. He understands how all three phases of this rocket works, because the IU has to control the entire rocket. It’s time to get smarter every day and understand the Saturn V! You can see pictures of Luke and his wife attending the launch of the Saturn V rocket. He is an award winning Apollo engineer, and one of the most impressive photos is of Luke and his young bride, Kitty, at the launch pad for Apollo 13. It was April 1970, and Luke is the perfect person to teach us about the Saturn V because he has seen one launch and worked on the instrument unit that had to touch every single component of the rocket. He is hyper-intelligent and knows the facts and numbers, so we’re going to start at the first stage, then move to the second stage, then the third stage and talk about the launch escape system. We’ll also learn that the four outer engines are gimballed and each one produces 1.5 million pounds of thrust, and burns a ton of kerosene and two tons of liquid oxygen every second. We had to measure and program the computer system so that we knew not to move the center engine, which is fixed. Each of the four outer engines can move, and they have actuators which are hydraulic servo mechanisms controlled by the computer in the instrument unit. The hydraulic fluid is kerosene, which saves weight and complexity. In order to ensure reliability, there are 5 million parts in the system, so each part needs to have a 99.99% chance of making the mission. The engine also has a jet turbine of about 50,000 horsepower, and the thrust chamber has a temperature of 5900 degrees. To cool the engine, kerosene is routed down fine tubes in the thrust chamber, and liquid oxygen is squirted through an injector plate with 6000 holes. The four outer engines are gimballed with the help of a guidance platform in the instrument unit, which reads the platform 25 times a second and calculates which engines need to be gimballed in order to steer in the right direction. You know, they have the x-ray.And they check it out and they make sure it’s all good.
Do I need pitch, yaw, and roll? Do I need all of the above? That’s amazing. In order to keep the heat away from the center engine, they have insulating blankets on the engine, base, and other parts. Interesting! In South Alabama, you can get a $2 pistol? Yeah, I like that song too. That’s amazing. So, the first stage burns two and a half minutes and takes the rocket up to 40 miles high and 5000 miles an hour. At that altitude, the rocket still keeps climbing until it reaches 70 miles high. When it hits the Atlantic, it pieces just go everywhere. Yeah, kablooie! To get rid of the extra mass, the rocket separates from the second stage and tilts down. The fuel tank is made out of aluminum plate, which is inch by inch and two inch and three quarter thickness. They form a flat plate, mill the inner surface for strength and some slosh baffling, and then put it in a giant press and bend it. The plate is then welded together with an automated welder, which takes 20 to 30 passes. The welds are then checked out with a microscope and x-ray to make sure it’s all good. They said you’d be hard pressed in most cases to tell the Virgin Aluminum from the weld, indicating that they were very, very precise craftsmen. The forces from the engines are transmitted out through the structure and all the forces are transmitted upward through the skin, with no internal beams or anything like that. This means that the tank must withstand the upward force, plus the pressure in the tank called hoop stress. The inner tank areas are made with a corrugated material, allowing for a lighter weight material because it only has to withstand the upward force, not the inside pressure. The corrugated material has a bigger cross section so that it can withstand more axial, and it’s not going to buckle. The liquid oxygen lines actually run through the fuel tank, which is 18 inches in diameter. This is because bringing them out around the tank would mess up the streamlining on the rocket. The tank is insulated like a thermos bottle, with an inner wall, outer wall, and a low pressure gas in between. The oxygen tank is on top and has a 2 to 1 ratio of oxygen to kerosene, with both having the same density. The injector plate down in the throat of the engine has 5000 holes, with some spraying kerosene and some spraying liquid oxygen. Originally, this engine was developed by the Air Force for a heavy lift rocket, but the technology got ahead of them and it was transferred to NASA to be used on the Saturn. The baffles were added because the gas started circulating in a circular motion at 2000 R.P.M.. Problem with that is sometimes the injectors don’t mix well, resulting in too much oxygen in an area and not enough kerosene, leading to an engine that acts like a car running rough on the road. To solve this, baffles are used to break the swirling motion into much smaller areas, which helps with complete mixing. Several injector designs have been tested, such as the LOX dispersion injector, baffled, divergent ring injector, low fuel delta injector 21 compartment baffled injector, and the divergent ring injector. These baffles are enough to solve the problem.
The exhaust from the turbine is cooled by routing it around a nozzle extension made of high strength stainless steel, which is injected into the walls of the nozzle extension. This way, the exhaust temperature is only about 1200 degrees, which produces 18-20,000 lbs of thrust.
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Okay, now we’ll get to the top of this stage. We were talking about ground handling equipment. You see this big yellow structure on the top of it. This is how you lift this thing off of the transporter and pick it up and put it on the launch pad. Then you would remove this yellow structure up here and then there’s a piece missing that would go from the base of the stage at about where I’m standing, I think it’s 12 or 15 feet, something like that.
So you and your team, whoever controlled the firing and the timing sequences and things like that. So we’ve lit off the engines, we’ve burned all of our fuel, and it comes time to do separation. So you have to shut the Main Engine Cut Off (MECO). And then there are four fins on the base. There’s a fairing that flares out so that your engine you can gimlet without the atmosphere streaking by and holding you keep you from gimballing. All right and then in that fairing there is a fin, all right there’s four of them around it. Well at the base of that fin pointing in this direction, there are two big solid rocket motors. So there are eight of them around that thing.
So this thing is connected to this inner stage with a set of ordnance. Okay. So your computer says, all right, time to shut it down. Main engine cut off fires this ordnance. This ordnance now separates the stages are strapped together with tension straps. Around the interior of those straps is the ordnance. The computer fires the ordnance severs these at the same time fires those retro rockets to slow this thing down, doesn’t back it up, just slows it a little bit. This piece that is missing up here, the inner stage, there are eight more solid rocket motors around it and they’re fired at the same time to put thrust on the upper….on the second stage to keep the propellant seated in the tanks so I can get these engines started. Because of slosh.
That’s right. You got to get that stuff down in the tank. Otherwise, when you shut off, it just kind of wants to float forward, okay. So you have to have a little bit of thrust to pull that stuff back and get these engines going, once you get these engines going. Then you jettison this inner stage and that’s to get rid of excess weight.
So there’s a lot more going on in stage separation. Oh Yeah! Okay, so check me here. So engines cut off. Yeah. And then we blow the tension straps here. Yep. And then we have those retro rockets, Yep. On the fins? That’s right. Free, those to slow this down. Right. And then we have a kick right here. And we have these, these are called ullage rockets. Oh, okay. So we have a little… Push forward a little bit.. Yeah, a little kick in the pants seat my tanks. Fuel and propellant in the tanks. And then start these engines. Now, these engines first stage one and a half million pounds of thrust. F-1’s, these are J-2 engines. Now the fuel here is liquid hydrogen, which gives a lot more efficiency than kerosene. However, it is much harder to handle, since it has to be kept at a temperature of 426 degrees below zero. Each of these engines produces 230,000 pounds of thrust with only 600 pounds of propellant per second, which is much more efficient than the three tons of propellant needed for the first stage engine to produce one half million pounds of thrust. The pumps for the liquid hydrogen have to work hard, since it has a low density of 7/10ths of a pound per gallon, compared to the 9 pounds per gallon for liquid oxygen. These pumps spin at a rate of 37,000 revolutions per minute, much faster than the 5000 revolutions per minute of the first stage engine. All of these engines are controlled by the Instrument Unit on top of the third stage. The stages are connected through the interstage with 20-30 cables and a back up explosive blade to ensure that the stages are cut free. The second and third stages use a common bulkhead between the two tanks to save length and weight. A lot of people have spent their entire lives working on just one part of the J2 engine, which is used on the second and third stages. What’s a common bulkhead? The bulkhead that is shared between the oxygen and hydrogen tanks is a common bulkhead. The second stage of the rocket is insulated on the outside with a phenolic honeycomb grid filled with foam to protect it from the extreme cold of the hydrogen tank. The third stage is insulated on the inside of the tank and has an auxiliary propulsion system (APS) with hypergolic Nitrogen tetroxide and hydrazine to give roll control while the engines are burning. The first stage shuts down at 40 miles high and falls into the Atlantic Ocean about 450 miles from the Cape. The second stage shuts down at 115 miles high and breaks up at an altitude of about 2000-2500 miles from the Cape. The third stage burns for 2 minutes and takes the rocket to 117 miles high and 17,500 miles an hour, putting it in orbit. Now, the problem we have here is that we are going to the moon, but we launch from the Cape. You can only launch in certain directions from the Cape, so what you do is you launch and you wind up in an orbit about the earth, but the orbit plane is in a different plane from the plane of the moon. That’s also orbiting the earth. We go into orbit, we shut this thing down, usually coast an orbit and a half. We could have coasted as much as 6 hours before batteries ran out, usually only coast an hour and a half or so, 2 hours. And what we do is, we come around in our orbit and it intersects the plane of the moon’s orbit, we restart this engine again. So this one burns twice and will burn for about 6 minutes, taking them out of their orbit plane and into the moon’s orbit plane, and up to 24,500 miles an hour. Now they’re on their way to the moon, and after that, the crew’s got to get separated and do all their magic.
If you want to know about the little thing that went to the moon, like the actual landing part, go to Johnson Space Center. This model here shows the third stage, the instrument unit and the lunar module is inside what’s called a spacecraft lunar module adapter, the SLA, and then the service module atop that. And atop that is the command module, where the three astronauts are located. There’s also an emergency detection system in the instrument unit, which is triple redundant and wired. If two engines were lost on the first stage, this system would automatically fire a rocket motor that’s in the launch escape tower, pulling the command module with the crew wherever the abort occurred, taking them 30 to 40,000 feet higher and then they would jettison and come down on their parachutes. During second stage burn, the launch escape system has a cover that is over the top of the spacecraft, and the astronauts can only see out of a little window down at the side. When the launch escape tower separates, it pulls that conical section with it as part of the so, and it fires just after second stage burn starts. It has a little motor at the front of it that will pull it away and pitch it up out of the flight path. We’ll fire the thrusters.We’ll slow it down and then it will eventually fall into the moon.
D - So there’s a little motor on top? L - Yeah, there’s a couple of little extra auxiliary motors inside that thing. D - Is it a pretty dumb rocket up there? It’s solid right? Yesh it’s solid. So that that thing has as much thrust as is a redstone rocket just doesn’t burn as long. It’ll snatch them away there real quick. They will pull some G’s.
D - Really…L - Probably slower if that ever happened. Luckily we never had that happen. D - It’s amazing. I did not realize that you jettisoned that is the word jettison? L - Mm-Hmm I didn’t realize you jettisoned that while the second stage was burning. Yeah, just after second stage gets up burning. Then you get rid of it. Now the the instrument unit, we talked about it. This is where it’s located on top of the third stage. Okay. Now, when the when we get to this point, we will just the lunar module is inside the tapered section up here. We’ve jettisoned that launch escape tower so it’s no longer there. The command module and the service module are gonna stay together until just before they reenter the Earth’s atmosphere coming home.
So at this point now they’re heading toward the moon where, you know, we’re probably 6 or 800 miles above the earth, not very far YET. Still got about three days to get to the moon. So the crew now, the command module, service module’s together they will separate from this ,the SLA, the spacecraft lunar module adapter. They will separate and move away from the space, from the rocket, and then it’ll turn around. Okay. As they’re turning around, we’ll jettison four panels on this SLA here, which is part of the instrument unit control stuff again. Then the command will jettison these four panels. That leaves the lunar module still attached to this lower part of the floor. With the top end of the lunar module pointing forward, the command module goes out, turns around, comes back and docks with the top part of the lunar module. They dock, and then they will set a hook up some cables and some latches, and they throw a switch in the command module and that releases the lunar module from the rocket.
Now they’re going on their way to the moon. Now the moon’s up here. They’re down here three days away almost. They, they the spacecraft. Moon’s moving like so, they will follow a trajectory and go around the LEADING Edge of the moon. Fire that service module engine, slow ’em down. Put them in orbit, do their thing, and then they use the service module to get away. When we shut down the stage, we’re going 24,500 miles an hour. We’re only a few hundred miles above the earth, so earth’s gravity is slowing them down very quick. By the time the crew separates, this thing is probably everything is probably slowed down to maybe 12, 14,000 miles an hour because you’re still very close to the earth. Earth’s gravity and come on back home guys.
So this thing now when they separate. They will slow. This would slow this stage down maybe seven miles an hour, eight miles an hour. They would speed up the spacecraft a few miles an hour. And the reason is so much momentum with this. If we did not slow this stage down, there was a very high probability that BEFORE they reach the moon, The S-IVB stage would run into the spacecraft.
D- Oh! Okay, so this was a safety. D - So their flight…they may be flying in formation. And you don’t want that. And they’re right there. Well, you’re going you know, you’re going to the same place if you don’t do something. So we would make that was a safety measure.
D - How would you fire where were the rockets at? L - That’s that auxiliary propulsion system back there. D - The little black thing right there. Okay. Once we had done that maneuver and everything was okay. Now, depending on the mission, the early missions, what we would do then is we would actually reorient the stage, pump some propellant out the back of it that’s left A little bit of propellant left Don’t fire the engine. Just pump it out of it. Fire some thrusters and the moon’s up here. So we’ll slow it. We’ll fire the thrusters. We’ll slow it down and then it will eventually fall into the moon. D - Really!? L - We get within 2000 miles of the moon, the moon’s gravity. Now, throw this in orbit around the sun. So we got five of these orbiting the sun. D - Right now? L - Right now. Now, beginning with Apollo 12, the astronauts would leave the instrument packages on the moon called Apollo Lunar Surface Experiment Package, “ALSEP”. ONE of the science objectives of Apollo was to determine what the interior of the moon..what’s the consistency..Do we have, does it have a molten core like the earth? Is it sort of like a consistent density? Or does it have mass concentrations? Which it turns out it does….So beginning with Apollo 13 after 12. And every time they land, they leave an ALSEP package. So Apollo 13, instead of slowing it 85 miles an hour we slow it 45 and slam it into the moon. This thing hitting the moon is about somewhere around 10 to 11 tons of TNT. D- {Gasps} What!? It would create about a two and a half to three hour moon quake. It rattle it pretty good. All the green men are running around. Oh…the Americans are back! {both laugh} It would be a moonquake. It’s not an earthquake. That’s right, a moonquake. And so so the computers that you controlled to fire that package, the APS right there. So this computer would control that APS. Right. And instead of 85 miles an hour deceleration, you’d give it, what did you say 45? Just how many seconds do I burn. D- And so there was a conversation, “Hey, computer team” “we need you to fire this much so we can slam this into the moon.” L - These were all preprogrammed and preplanned. So this is a little loud because the air conditioning unit back there. But this is what you worked on. L - Yes. L- It’s the Instrument Unit it sits on top of the third stage. Basically, the thing is set up like this so that you can distribute your weight around the outside of the thing and control your center of gravity and so forth you know. The hope was that we would go on with an Apollo application program and with this layout like this, with a different thermal conducting panels, we could move equipment around and, you know, do different experiments. D - So this thing set on top of the third stage, L- Top of the third stage. D - And controlled the whole rocket. L - That’s right. Those lines up at the top up there, you see going down, those were the lines that went down, connect to the other stages to allow us to communicate with them. D.-That’s awesome. And there were methods in the system for separation to disconnect the cable. D - And we made another video about the the computer over there. That’s a whole different thing idn’t it? Yeah. So I guess, I guess if you want to learn more about the computer for Saturn 5, you should just go watch that video, I guess. So when you look at this thing right here, so this is the computer, the instrumentation ring, right? L - Yeah D - What do you FEEL when you see this? What do I feel? Yeah…Nothing? [Long Pause] Yeah I’ve been there before. Yeah, yeah. Well, it’s, it’s. You know, it brings back a lot of good memories. I know that because this was, uh so many of us that were came in work on this program were right out of college. So this is something that nobody had ever done before. And it was a great learning experience because there were there’s so many different aspects to it. You know, technology goes from, you know, the RF technology to transmit the data to the ground, the telemetry systems and so forth, the environmental control system. So did you feel like a pioneer? I just felt like somebody who didn’t know what the heck was going on. I got out…I finished college in 1965. Okay. I had had zero computer courses of any kind, no digital anything. It was all analog. In fact, all my stuff was like TVA power, you know, having big power stuff. So I came here and had to learn a whole nother world. It’s kind of sad that the Apollo Program hasn’t been promoted more, considering it had 300,000 contractors and 47,000 NASA employees working on it at its peak. Many of the contractors had come straight out of college, and after the program phased down, they moved into other fields. One of these contractors, who had worked on the computer control system for Skylab, went on to work on a Patriot missile program, before eventually being sent back to school to get a computer science degree. His last job was writing software to read handwritten amounts off personal checks - one of the first widespread commercial applications of machine learning. After 31 years at IBM, he retired and moved back to Huntsville, where he worked on Patriot again for 19 years.
One of the most impressive feats of the Apollo Program was the mission of Apollo 12. They aimed to send the spacecraft 2000 miles past the trailing edge of the moon in order to throw it into a solar orbit. However, the tracking system had overestimated the speed, and the spacecraft missed the moon by several thousand miles. As a result, the spacecraft ended up in a very high orbit around the Earth, with the gravity of the moon and the sun equalizing at the Lagrange L1 point. After several years, the orbit stretched out and the spacecraft was pulled into an orbit around the sun - something that nobody had predicted. In 2002, an amateur astronomer spotted the white dot, and JPL and MIT started looking into it. It was eventually discovered to be the spacecraft from the Apollo 12 mission. And I want to thank her for allowing him to do this with me.
Destin was amazed by what Luke had to say about the Apollo 12 mission and the resulting Lagrange point that followed the Earth around the sun. He was also impressed by the fact that JPL predicted that the S-IVB would come back into orbit around the Earth every 40 years for the next thousand or 2000 years. When Destin heard about the impact of a small module firing at 25 miles per hour, he couldn’t help but laugh. He was also amazed that his grandkids might see the same thing in the future. Finally, Destin was grateful to Luke for talking about his amazing wife, Kitty, and thanked her for allowing him to do this with him. We are deeply saddened to announce the passing of Kitty Talley, a driving force and enabling force behind Luke’s successes, just as Tara is to me. We owe a huge thank you to Kitty, who was not able to watch this video, but was a very special person in Luke’s life, as well as the 350,000 people who made the Apollo program happen. Luke wanted to make sure to emphasize that he was not the only one involved in the Apollo program, but his humility is admirable.
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