The Clean Pad
The Clean Pad
Pete Portanova, principal engineer/scientist, Launch, has worked at The Aerospace Corporation for more than 47 years. He was the first principal director for EELV. The following is an excerpt from an oral history interview conducted with Portanova on October 1, 2009, at the Aerospace offices in El Segundo, California.
“The clean concept design gives flexibility when you don’t have a lot of territory that you can build facilities on, like at Vandenberg. Maybe at the Cape it’s a little bit more plentiful. So every time you want to go from one configuration to another you can do it. In the past we basically designed the pad to one configuration, and there was no flexibility. But the big part here, the big tenet of this, the clean pad, is that the vehicle goes to the pad only when you’re ready to launch. When you go to the pad, you check the interfaces, you load up with the propellant, and you launch it. You don’t spend days or weeks. You initially may have to spend a few days, but you can probably get it down to one.
On SLC 41—I think it was the second flight—we got down to the pad, and there was a malfunction in one of the boxes. This particular box was a removable box, LRU, which meant you can remove and replace it, which was fortunate. There were no propellants onboard. We took the vehicle, the Atlas V, dragged it back to the vertical integration facility and removed and replaced the particular box, and brought it back down to the pad and checked everything—loaded it up with the propellant, and launched it all within 24 hours. Now, when there are propellants onboard, you have to detank, and of course, put it into safety, so it takes a little bit more time. But the point is that you don’t spend time on the pad. With a high launch rate, a clean pad could really pay off.
The pad is more or less like a runway. The aircraft goes out to the runway, revs up, and may hold for 5 or 10 minutes because of the traffic, but generally speaking, it takes off. You’re not going out there to sit there for two days, or two weeks, or two months to check it out, or change a tire, or whatever. It doesn’t go out there and do maintenance or repairs, or become part of the factory.
Unfortunately, with the Titans, the launchpads became the factory, the end of the factory, which may be OK if you have a very low launch rate. The pad should not be the end of the factory. The vertical integration facility is x number of feet away from the pad—it’s a check-out cell. OK. That one cell has a certain time line. We’ve done a lot of analysis on certain time lines. Let’s say just for the purpose of discussion, you can completely checkout one vehicle per month. That means you can have a launch rate of about 11 to 12 per year. If you need to go to a high launch rate—if you need to launch 20 times a year, or something like that, you have to build another check-out cell.
That’s not really saving anything. The only thing you’re saving is that you’ve got the same pad—it comes down to the same pad. What that does is you don’t have the pad as a choke point—the pad is the choke point if you’re not careful. For example, the other scenario is you go down to the pad and you’re sitting there like we’ve already done for months and months. What if you had a requirement to launch another vehicle, what are you going to have to do? Probably take it off the pad or miss that launch, you slip that launch. If you want to get rid of the choke point, and if you don’t want the pad to be the end of the factory, the clean pad is your answer.”
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