NTB: You recently designed and developed a unique aircraft jacking system that allows an aircraft to “float” during ground vibration testing. Please explain for us, if you will, how that system works and how you came up with the idea.
Ginn: Every time we do a ground vibration test, we always want to come up with a way to isolate the vehicle from the ground so we can get the most pure data when we excite the vehicle, and it’s the easiest for the analytical modelers to update their models with the information. So, there are different techniques for doing that. You can use bungee cords…
NTB: That’s not very sophisticated, is it?
Ginn: No, it’s not very sophisticated. Some of the things you do just always work, and sometimes you just need to do them even though they’re not sophisticated. But then people started trying to figure out how to put test articles on air bearings. Right before I started with the branch we actually had a company design this air bearing for us, and it’s big, and it’s heavy, and you have to get it underneath an airplane under the jacking points, and to do that it’s a very hazardous situation. You have a big crane that’s suspending an entire F-18, and you have to retract the gear, and then you have three people move these huge air bearings underneath the vehicle. It takes three people to move each one into place, so you had a lot of people spending a lot of time under suspended aircraft. It’s not ideal, so it was just one of those things that you see a couple of times and people in our group started to say, “We’ve got to come up with a way to incorporate these air bearings in some sort of aircraft jacking mechanism.”
Even after I knew I was going to work at Dryden, I decided not to do aerospace as my background; I was much more mechanical-minded. Any kind of opportunity that comes with trying to figure out how to fix something or make something work better, sparks my interest, so as soon as somebody mentioned that, I said, “Put me on the job. I’ll figure something out.”
It was one of those things where it was not on the front burner of any of Dryden’s projects so they could say, “Yeah, let’s put a bunch of funding into this idea,” so it really took a lot of my own resourcefulness. After I’d get all my project work done, I’d be spending time working on designs, vetting it with some other engineers, making sure it all looked kosher. It actually took several summers. I’d have co-ops or interns helping me, just so that I could still get my day-to-day work done. But it was definitely worth the effort.
What's great about this system is, you have an airplane now that’s sitting on its gear, and you just roll the system right underneath at the jacking points, like you would an aircraft jack. It’s electrically activated, so I have electric motors driving these actuators that then pick up the vehicle, and while the vehicle is resting on the soft support we’re able to retract the gear, because that’s a critical testing consideration. We need to be in “gear-up,” because that’s how the airplane is most of the time. Then we just inflate the system. It takes all of a half-hour, which before, we had to have meeting after meeting after meeting to coordinate such a hazardous task. It would take a whole day just to get an airplane on the isolators, so it saved a lot of time, and it saved a lot of money in terms of not having anything fall that’s one-of-a-kind.
We've now had three opportunities to use it. We’ve used it on our G3 airplane; we used it on our F-15 airplane; and I just got done using it on the Orion Pad Abort Crew Module.
NTB: That’s the new crew vehicle, right?
Ginn: That’s correct. That’s the new crew vehicle.
NTB: How long did it take you to get this system in place and operational?
Ginn: Once we started cutting metal, it was probably, I guess, about a year-and-a-half to get all the parts and get it assembled. I had to build up manuals for it. I mean, it’s a very formal system. It had its own task analysis; it has its own maintenance book. Then I had to set up the whole proof testing for it. We put 108,000 pounds on the entire system to proof test it. So I designed all the fixturing that it took to do the proof test. As soon as that test was done, within a month, we were actually using it. I actually completed it in December 2005 and it was used for the first time in January 2006.
The whole idea started in 2002, just to give you an idea of how long it took to come up with the money. It’s a system that, throughout the years, has added up to at least $200,000 of materials and off-the-shelf parts, so part of the money resourcefulness was, each year, kind of going around and trying to get people’s end-of-year money, or find little scraps of money or people who were interested in investing in it, and it took a couple of years to build up all the parts we needed.