B-52 model brought to life by machine programmers

  • Published
  • By Patrick Ary & Shawn Jacobs
  • AEDC/PA
ARNOLD AIR FORCE BASE, Tenn. --  To hear Paul Denton and Joel Gregory talk about it, the most important aspect of building a one-tenth scale model of a B-52H was patience, not their skill. That's the way they consider most of what they do.

"Sometimes it can get real involved," Gregory said. "But basically we get a model, we make a tool path, we'll send it to the shop and the guys will cut it. That's the simplified version of it."

Denton and Gregory, numerical control (NC) programmers at the AEDC Model Shop, spent months programming the shop's machines to cut massive pieces of metal into the parts that became the B-52H model used for store separation testing in the Propulsion Wind Tunnel Facility's (PWT) 16-foot transonic wind tunnel.

The model is one of the largest ever built at AEDC for use in testing and, even though the schedule for completing the model was tight, it was a welcome break from the normal routine.

"It has been fun," Gregory said. "It's one of those jobs that's interesting, because a lot of times all we see are ducts and hardware that go in all our facilities. It's neat to work on models. Those are the fun jobs."

While it may have been fun, that doesn't mean the work was simple. Because of the tight schedule, designers sent Gregory and Denton 3-D models of each part as they finished it.

"It's not totally unheard of," said model designer Scott Wieland. "We have done this kind of thing before but to a lesser extent. If we need parts quickly, we will send them to the Model Shop and have them proceed before a completed drawing is done. It's outside the normal process, and it takes a buy-in from management. They have to be willing to accept the risks when we do this."

Once they received the computer file from designers, Denton and Gregory consulted with Model Shop machinists to determine the best position to start cutting the blocks of metal into the final product. After developing a game plan, Denton and Gregory started generating programs that would trace the path a tool would take. Those were eventually loaded onto the various machines to make rough initial cuts of the metal and eventually the finishing cuts.

Denton and Gregory's programs generate coordinates on a three-dimensional plane. Those coordinates tell the cutting tools what paths to take in cutting the metal.

"It'll generate a bunch of numbers ... millions of numbers," Gregory said. "And I will feed that to the machine and I'll tell (the machinist) where the origin is. We have a numbering system that we set up for these programs, and we'll say OK, run such-and-such number program with the part set up this way. They'll do it and hopefully, at the end of the day, it'll be something that looks kind of like what we have on the screen."

Piece by piece, Denton and Gregory generated programs for the individual parts sent to them by designers. The major parts consisted of the B-52's wings, engine pods and segmented sections that were later bolted together to form the plane's body. Programs for some of the parts were large files, consisting of numbers that in at least one case was more than five times the length of Leo Tolstoy's "War and Peace" - a book that is about 1,400 pages long, depending on the version.

In addition to the hours spent generating the programs, Denton and Gregory checked all of the programs to ensure they weren't making any errant cuts that could destroy the part and require the work to be started over again.

Denton and Gregory worked about 58 hours a week to try and get all the programs ready at the right time. They say they weren't worried about getting the project finished on time, but they had enough to keep them busy.

"The fact that they wanted it so early was going to push us a lot because there are only two programmers, and we have to supply the programs for the machine tools," Denton said. "And there are quite a few of them."

Machine Shop Planner Jeff Harvey became involved in the B-52H project even before Denton and Gregory. He had to determine if the Model Shop would have the capability of doing the job to begin with, especially in such a short time period.

"I felt like we could do it and committed to it and then just basically tried to work out the schedule to make everything work out right," Harvey said. "The guys did a great job in making that happen. I was relatively optimistic about it the whole way."

"I was glad that we got this [because] this is the Model Shop. This is a model, so we want to do it here. I believed that if we were able to get this model and were successful, it's something the base could be proud of."

Harvey said the sheer size of the model is impressive, and the fact that it's made mainly of aluminum was helpful to the model builders and to meeting the schedule.

"It's big, but there aren't a lot of small complexities with it, so that helped out a lot, too," he said. "The job was enormous and to shove it into that short of a time frame and have everything come together correctly took a lot of work."

And the fact that the model is a legacy aircraft like the B-52? Well, that just made the project more exciting.

"You know everybody's impressed by a B-52," Harvey said. "I think there's even more excitement than maybe even the F-22. We're proud of it, and we hope to get a lot of testing time from this model."

ATA Model Shop manager Walt Bishop said everyone involved with the project went above and beyond on a job that could have suffered serious setbacks in the program schedule if any part of the system had broken down. He says the NC programming was a key part of the process.

"They're kind of the unsung heroes," Bishop said. "The work that they did, taking what came from Scott Wieland, making those programs, coming down, putting them in, checking them out, keeping the guys busy ... if they had gotten sick at any point in time, if they had not done their jobs as efficiently as they had done and as professionally as they had done, we would have had problems."

Both programmers say they enjoyed the work despite the hectic schedule, and they would be willing and ready to take on another model.

"It's been an interesting job to work on," Gregory said. "It's also been highly visible. I've worked here almost 25 years and I have never seen the people come in to see a job that we were working in the shop as much as this one. We have had countless tours come through, from the AFMC commander on down."