Development Motor 1 Test Firing
- Deborah Crane
- Gordon Russell
- Amy Baesler
- Chris Rosson
Development Motor Tests are always visually spectacular, but what are engineers really trying to learn during the 2 minute molten blast? NASA EDGE talked to several engineers working on the DM-1 Test at ATK in Promontory, UT to get answers to that question and a few more. Download NE@Fahrenheit 6000 and find out everything Chris and Blair learned… all from a safe distance. If you pay careful attention, you may just discover yet another advantage of the brilliantly designed engineering smocks.
CHRIS: Welcome to NASA EDGE.
BLAIR: An inside and outside look at all things NASA.
CHRIS: We’re at ATK in…
BLAIR: … Promontory, Utah.
CHRIS: Behind us is a development motor or DM-1.
BLAIR: Yes, for the Ares I first stage rocket.
CHRIS: A lot of the ATK guys are getting ready for this first test firing.
BLAIR: To understand what’s going on for this test, we had an opportunity yesterday to talk to some NASA engineers and some ATK engineers.
CHRIS: How do we go about doing a test like this?
BLAIR: I want to know.
CHRIS: Especially this structure, why is it a horizontal test as opposed to a vertical test? What kind of propulsion systems are we using here?
BLAIR: Is this a pass-fail thing?
CHRIS: What kind of data are they going to be collecting?
BLAIR: These guys really know their stuff, so stick around and you’ll get the answers to those questions.
CHRIS: We’ll come back right after the test.
BLAIR: Yes, from a safe distance.
BLAIR: We’re here at what I consider to be a very safe distance from the test tomorrow for the Ares I five stage motor. We’re here with Deborah. Deborah, what can you tell us about what we’re going to experience tomorrow?
DEBORAH: What you’re going to see tomorrow is a lot of fire and smoke because they ignite this 150-foot motor that has 1½ million lbs. of solid rocket fuel that burns a little over 2 minutes. We will get to see this entire motor go through its whole burning operational phase.
CHRIS: It’s like a big roman candle.
DEBORAH: It’s a huge roman candle.
CHRIS: What do we have behind us?
GORDON: We have the first static test motor for the Ares program at NASA.
CHRIS: You’re feeling kind of stiff. Are you okay?
GORDON: I’m all right. I’m nervous a little bit.
BLAIR: Who wouldn’t be nervous when you’re standing behind a nozzle of SRB of massive proportion?
CHRIS: Are we safe right here? Are we okay?
GORDON: I’m assured that we’re safe but I get a little nervous sometimes too.
CHRIS: Do you? All right.
GORDON: Not as bad as when you crawl inside that thing and are surrounded by 1.5 million lbs. of propellant.
CHRIS: Whoa, wait a second. You actually crawl inside that with the propellant?
GORDON: People do. I’ve been up there a few times.
BLAIR: Did you loose an inner office bet or something?
GORDON: One of the times I did lose a bet. We all draw straws on who has to be the one to crawl in there.
CHRIS: I’m looking at this mirror. We have this mirror in front of us. What’s that silver structure in the back of the solid rocket motor?
AMY: We have this new structure called the skirt side load fixture. Pre-test and post-test we’re going to apply side force, plus or minus 200,000 lbs, then we get a better idea of what the static test is doing.
CHRIS: The purpose of that is when Ares I eventually takes off that vehicle will be rolling.
AMY: Right. Since there’s only one stick on the Ares vehicle, roll is a concern. We need to know how much roll and be able to design for that.
CHRIS: This is a five-segment SRB that’s a derivative of the shuttle SRB. What are some of the improvements that you’ve made on this particular motor compared to the other?
GORDON: We’ve made the nozzle a little bigger, opened the hole or throat that you see there. We’re trying to control the propellant or thrust, pressure inside the motor. The propellant burns a little hotter. You thought it was hot enough before but now you stand here it’s going to get a little hotter.
GORDON: It gives us more power, more thrust.
CHRIS: Is the propellant geometry the same as the shuttle SRB?
GORDON: There are some changes to it.
GORDON: Minor changes.
BLAIR: Geometry questions are always compelling for the program.
DEBORAH: The formulation is a little bit different to get a different burn rate.
BLAIR: What is the formula?
DEBORAH: I cannot tell you.
BLAIR: I gave it a shot.
DEBORAH: There are a few things that are known. There is ammonium perchlorate. There’s aluminum. There’s iron oxide. When you mix all this together with other things it feels very much like an eraser at the end of an actual lead pencil eraser?
CHRIS ROSSON: I’m the Insulation Subsystem Manager for the Ares First Stage for Marshall Space Flight Center.
BLAIR: That’s an impressive title.
ROSSON: It is. It’s much too long though. I need a shorter one.
BLAIR: I say, just go with Inspector 12.
BLAIR: You heard it here first.
BLAIR: Where do you get insulation that can handle that kind of thing? Lowe’s?
ROSSON: We thought about going with Lowe’s but they didn’t have enough capacity to help us. We actually get it from our contractor in California, which is Kirkhill Rubber Company.
CHRIS: Why does it burn from top of the rocket down as opposed from the bottom to the top?
DEBORAH: You have your igniter. A lot of it is the pressure drop as it goes down the core of the cylinder. So your igniter is always at the head. Because you’re pushing the gases out you have to start somewhere, of course. You have to ignite it from there. It starts to burn and erode through all the propellant and your gas gets propelled out the backside of the nozzle.
BLAIR: Is this like a standard igniter that you have on a gas grill or is this much more?
DEBORAH: It’s similar but a lot bigger and a lot more powerful.
BLAIR: That makes sense considering the scope of this test.
BLAIR: Is it a graded test or a pass-fail? What makes this a successful test?
GORDON: It depends on the objective. But yes, a lot of it is pass-fail but do we meet the ranges of gauges and temperatures that we’re looking for and pressure measurements? Pressure is a big one.
CHRIS: When you have this long solid rocket motor, what kind of structure do you need in place to hold it? It has to be a pretty strong structure?
AMY: Yes, it does. We have a forward test stand, which the primary roll of the forward test stand is to measure the axial thrust. That supports the forward end. Then we have an aft test stand that measures primarily the lateral or side force that the nozzle vectoring causes. That supports the back end.
CHRIS: Why is this test a horizontal static test as opposed to the rocket being vertical?
DEBORAH: It would be hard to put it vertically because it has a lot of instrumentation. We’re getting data, temperature data, pressure data, strain gauge data, accelerometer data, load data…
CHRIS: Got all that?
BLAIR: That’s a lot of data.
DEBORAH: There’s a lot of data and in order to do that, it’s much easier to put it horizontal and also you need to have it so it doesn’t go anywhere. You want it to stay in one place when you fire this thing. This support system is very strong in order to keep it so wherever you are you’re still at a safe distance.
BLAIR: Plus you don’t get the cool mountain carvings that you get after one of these cool tests.
DEBORAH: That’s very true. They actually fire it into the back of this mountain. As you can see, there’s a firebreak there as well. You’ll get a huge plume that will goes out and a lot of smoke that comes out. It’s a great show. It’s a very interesting test.
CHRIS: How much thrust are we looking at for this test?
AMY: We’re looking at 3.6 million lbs. of thrust.
AMY: That’s a lot.
CHRIS: What kind of temperatures are we looking at?
AMY: Plume temperature is about 6,000 degrees Fahrenheit.
CHRIS: 6,000 degrees Fahrenheit.
BLAIR: That’s pretty intense heat.
DEBORAH: It is. It’s intense.
CHRIS: It’s a lot of magnetospherence.
BLAIR: Yeah. The sun’s solar flares create magnetospherence. If this burns at approximately two-thirds of the temperature of the surface of the sun, are we going to get any solar flare type experiences from this test?
DEBORAH: I don’t think you will have to worry about that. That’s internal combustion.
BLAIR: I’ve noticed I have some safety concerns. What happens with this massive blast that takes place. It looks like you’ve created quite a mess for yourselves over here. Is there any shot for s’mores or cook out materials being used during the test?
GORDON: We’ve always wanted to take a picture of someone roasting a hot dog next to it. No, we don’t have anybody that close.
CHRIS: He has volunteered for the good of the cause to go out there with a marshmallow and see how he’s going to react to it.
BLAIR: I hear this is very flame retardant.
GORDON: You’re smock is flame retardant.
CHRIS: Nomex material, just like the astronauts have.
GORDON: I have come out here after a test. It’s kind of interesting. The flames are going to go out at an angle. There was a bush here once. It was a nice, big, green bush. Half of it was black and burnt away and the other half was just fine.
BLAIR: So very clean, precise burn from the rocket.
CHRIS: So we have to put you at the right angle for the marshmallow.
GORDON: Yeah, the right spot. You have to cook the marshmallow and keep the smock.
DEBORAH: Safety first.
BLAIR: Safety first.
CHRIS: You heard it from the rocket guru.
BLAIR: Yes, and you’re watching NASA EDGE, an inside and outside, safe look at…
CHRIS: …all things NASA.
Page Editor: Blair Allen