Issue 3 Weather Summer 2001
Chasing Storms in Rapid City: An Interview with Charlie Summers
Brian Conley, Sina Najafi and Charlie Summers
Charlie Summers is a research scientist and pilot for the Institute of Atmospheric Sciences [IAS] at the South Dakota School of Mines and Technology. He pilots the only airplane in the world capable of flying through thunderstorms to gather data for scientific research. Brian Conley and Sina Najafi talked to him about his career choice.What is the primary kind of research that you do at the Institute with your airplane?
The IAS does all kinds of research but the people associated with the T-28 have strictly been studying thunderstorms. Basically the airplane was built and is funded to do the one job that no other aircraft in the world can do, and that's to fly through a thunderstorm.
Can you talk about how the aircraft is constructed and what is unusual about it?
It's modified, of course, because an airplane couldn't go repeatedly through thunderstorms. About 23 years ago the school took a basic North American T-28 trainer built in 1949 for the US Air Force and then had it modified specifically for this job. This includes armor-plating the wings and tail. We have about 0.060 inch aluminum plating over the leading edges. The plating is wrapped over the wings, glued on and riveted. We also have to protect the half section—the horizontal stabilizers and the vertical stabilizers. The canopy has very thick Lexan glass so the hail won't break in. And then we've had to modify the engine a little bit. It's a reciprocating engine, which is a nine-cylinder radial engine that burns gas. It's not a jet. We had to armor plate some of the equipment on the engine also so that it wouldn't get damaged. All this adds an extra 600-700 pounds to the weight of the plane.
Was there precedence for this kind of modification?
No. Basically the idea developed from Paul Mcreedy who was one of the early weather engineers and researchers. He did a lot of work with gliders around thunderstorms out in California. He designed the modifications and then a firm implemented them. They then tested by shooting hail at it from the ground with a two-inch hail cannon. Initially it was trial and error to see how to operate it. They had an 800-horse power engine at first but it wouldn't fly very well. So now we have a 1,430-horsepower engine. With this bigger engine, we can go up to as high as 25-26,000 feet.
At what range is the heart of the thunderstorm?
Well, we go in all the way from 10-12,000 feet up to 20,000.
Were you trained by the plane's old pilots?
It's been a succession where each pilot trains the next. The first pilot had to be a pilot and a meteorologist. And then he trained the next pilot. I started about 8 years ago. We went to two pilots about five years ago because we found that with the longer projects it's pretty tough on one pilot.
How long is your average flight?
They're not very long because of fuel. We can normally fly about two hours, which is long enough if you spend about an hour of that inside a thunderstorm. We're only in the storm maybe five or six minutes at a time. Then we turn around and go right back through again. I've gone through some thunderstorms twenty times.
We have levels that we know we can survive. Then there are levels in some thunderstorms where we're not sure. So we sneak up on it, if you will. Imagine a round loaf of bread with the most intense part of the storm in the middle. We take a slice with the controller moving us over a little bit closer to the center every time. Once you're in the middle slice, your instruments have no idea which way you're going. We have no radar inside of the airplane. So you have no idea whether you're in the most intense part except by the feel. You can feel the turbulence and the amount of hail and lightning. But the controller will always give us a ninety-degree break-out point to escape the storm.
How do you actually stay inside the storm?
It's kind of unique. I have a controller on the ground. We never go to a project unless we have ground radar. Sometimes, like last summer, we had two ground radars. The Global Positioning System that we have in the airplane is down-linked into a computer on the ground which feeds it into the screen on the radar. We're using a weather research radar, not an air-traffic control radar. So the radar is optimized to watch the storm. And so we take our GPS track and superimpose it on that screen, so the controller on the ground can see where we're going. Because once you get into the storm you can't really see where you're going. We need somebody to control us.
What kind of measurements are you taking up there?
We measure the moisture content of the air. We can carry a maximum of three laser sensors. One of them counts small particles, and another one counts up to almost an inch-and-a-half size. The laser beam on the large one is almost a foot wide. We count anything between there. The sensor counts hail, rain drops, ice particles, and snow. It also sizes it and gives you the density. We can get moisture down to small droplets. We have a small droplet laser that can count down to very small-sized particles. We take the temperature in the cloud with two different thermometers. Everything is under the wings, because we want to keep it out in the clear air so it's not contaminated by exhaust or anything.
We can also measure the electrical intensity of the storm. For that we have field mills, which are FM generators that run on the wing tips, the belly, and the top of the airplane. I think we have about seven or eight of them on the airplane. We carry a computer on board, because all of the collecting sensors go to the computer. We down-link probably 50 percent of the data to the ground so we can get an almost instant read-out. Then we store everything that goes into the computer so that when we get on the ground we can play back everything we've collected. The field mills will tell us whether the electrical particles are building or subsiding. We can almost tell when we're going to get a lightning strike close by how the field mills build. We can tell the temperature in the cloud, the moisture level, the hail level, and how it is electrified.
What do you do when you know a lightning strike is about to happen?
You just fly though it. This summer I got hit. We get hit roughly every summer. Right now there's some twenty-plus hits on the airplane. When it hits the airplane, it goes out the tail, which is normally the exit point, and burns a hole. So we can tell when we have a little hole back there.
How big is an average thunderstorm?
This summer was the first summer that we went in what they call "super cells." To be a super cell, normally the bottoms could be 2-3000 feet above ground, and the tops are at 45,000 feet. You have to have hail, lightning, turbulence, and a hook cloud or a tornado in the bottom. We went into three of those last summer. One of them actually had a tornado.
Can you talk a little about the experience of flying through one of these storms? What do you see?
One of our enemies inside of the thunderstorm is ice because of the moisture level. There are some relatively dry thunderstorms, but some have a lot of moisture. We have relatively no capability to keep ice off of the airplane. So you can ice the canopy completely to the point where you can't see out at all. That doesn't matter because you're using instruments, but it does concern you. You want to keep an eye on the wings to see how much ice you're getting there.
What do you see when you look through the actual windshield? Is anything visible?
Not really, but you can hear the hail. It gets pretty loud. It sounds like a hammer pounding on the windscreen. You can hear that, you can see lightning…. The Super Cells were interesting because it was pretty much like a strobe light. We had lightning striking around us probably every two to three seconds.
We get thrown around. But of course we have a four-point suspension harness system and we wear a helmet. And we have a parachute in case we have structural damage and need to get out of the aircraft.
Have you ever parachuted?
Yes, but never from the T-28! You'd have to open the canopy and physically crawl over the side and miss the tail. In the book, there's a drawing by somebody trying to imagine how it would work!
Is it true that IMAX is making a movie about you?
They had talked to us. The one film that they already have about people flying into storms is probably a hurricane. Hurricanes are pretty easy to fly in.
A sound recording of one of Charlie Summers's flights is on the CD included in this issue.
Charlie Summer is a research scientist and pilot for the Institute of Atmospheric Sciences at the South Dakota School of Mines and Technology.
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