John Connolly - Similarities between the altair and apollo lunar landers.

bjbjD this sort of sizes up the two vehicles. I tried to make these pictures about the right scale relative to one another. The Apollo Lunar Module weighed about 16 tons. Our Altair Lunar Lander fully fueled weighs 45 tons. Um, the Apollo Lunar Module had an overall height of about 23 feet to the top of the antenna. So, you know, it was pretty tall. But the height to the deck actually wasn't too bad. It was maybe about 12 feet. Our lander, to the deck, is about 6 and a half meters. So it's about 20 feet to where you step off the porch and come down to the surface. And I'll talk a little bit about configuration studies here in a little bit. But this is a much taller machine than, uh, than the lunar lander we flew in Apollo and, um, it's much bigger around, too. It's 8.8 meters. It's basically an octagon that inscribes itself within an 8.8 meter diameter circle. A few other intersting factoids, though, I told you already about Altair being our, our eagle. Um, when we look back at the Apollo Lunar Module the folks who designed it, basically had nothing to go from. There was nothing else of this sort that existed. So they basically developed a whole lot of engineering on the fly, and they did it in about 7 years from the point that we started designing the vehicle to when we landed the first one with humans on the Moon. We have a little bit more leisurely pace. We have about 12 years between well, about 11 years now between now and when we have to fly this vehicle. And we have the benefit of all those, all that experience that came before us. The biggest difference, is in the Apollo missions, schedule was everything. We had to land on the Moon before the end of the decade, right? "I believe this nation should commit itself before this decade is out..." you know. [crowd laughter] So we had to land on the Moon before the decade was out. Um, and cost seemed almost tertiary in those constraints. Now, of course, cost is primary along with risk and things like schedule and some of those other constraints tend to be the secondary constraints. Um, but some things do stay the same. In the current configuration, both vehicles have four legs Um, both of 'em are two stages. You use one stage to land; another to come up off the surface. And, uh, and the crew stands during the flight. Uh, we...In a lunar gravity environment, one sixth G, even as you're decelerating on your way down to the Moon you're pulling at most one half Earth gravity. and so you're, you know, you're not really undergoing any heavy excelerations and so, uh as long as you're supported, you know, so you don't tip over sideways, uh, you can easily sustain your weight on the way down. Okay, so the question I get most often is "why does your lunar lander look so much like the Apollo" "Lunar Module? Why can't you be more creative?" And I have to explain why physics is basically the driver of this vehicle. Um, we're designing a vehicle that is basically a physics machine. It has to accomplish these big velocity changes and that means it's got big, big tanks of some kind of propellant Hydrogen and Oxygen in our case in the descent stage. Hypergols in the ascent stage. If you have big, big tanks of propellant, you need some kind of structure to contain those tanks in. So now you have to build a structure around big tanks, and you get something that looks like propulsive stage. It's gotta land, so you gotta put legs on it or something so it can settle down on the surface. The crew has to go in another part of it, so you have to build another stage. You probably don't want to carry the whole thing back to orbit, so it's a two-stage vehicle. Uh, and all of sudden, you start stacking all of these things up and you have to line everything down the center line, so the center of gravity remains in line. And you get something that looks like the lunar module. Maybe not quite as ugly but, you know, essentially the same thing. And so I have to explain to people why, through the design process, a lander ends up looking like a lander. The other thing I end up explaining is it's not surprising that it looks this way. When you look at how we designed the Apollo lander, we had certain technologies we had to use. We had certain propulsion technologies. We had certain structural efficiencies Um, we, um, and those things haven't really changed very much between Apollo and today. And propulsion and structure are the two things that are 90% of the mass of this lander. Now, the things that have changed like computer horsepower and avionics and things like that make up about one half of one percent of the mass of this lander. Those have gotten really good. So what we've done is we've gone from, you know, being eight tenths of a percent of the lander mass to being four tenths of a percent of the lander mass. So those have helped a little bit, but it's the, it's those big things you know, those, the heavy industy, propulsion and structure where we haven't really seen the technology improvements to put us into a new realm of design solutions. So because technology has only improved incrementally over the last four decades, and because the physics of getting to the Moon and getting back hasn't changed at all Uh, you would only expect the solutions to change incrementally. And so that's essentially why the vehicle looks like it does. That doesn't mean we're trying, not trying to be creative but it does say that it kinda puts you in a little box and limits how creative you can be. It also says the guys who designed the lunar module were pretty smart. I think I heard that from Fred before that the guys who designed the Apollo Command service module were pretty smart. Pretty amazing job they did given how little they had to start with. this sort of sizes up the two vehicles hstephenson Normal.dot hstephenson Microsoft Office Word VALADOR this sort of sizes up the two vehicles Title Microsoft Office Word Document MSWordDoc Word.Document.8