Aerospace engineers, chemical engineers, computer engineers, electrical engineers, materials engineers, systems engineers, what have you – all aim to make things work according to a set of requirements and under a set of constraints.
And while what they design is often fascinating, how they got there can be just as interesting – particularly at a company like Raytheon Technologies, where engineers work every day to push the limits of aerospace and defense technology.
Here, engineers from Raytheon Technologies’ four businesses walk through some of the hard problems they’ve solved, and how they solved them.
Building a high-performance computer inside a missile interceptor
It’s a problem as old as computers themselves: Heat management – how to handle the thermal energy created when electricity passes through a hard-working circuit.
Computer engineers have come up with all kinds of techniques through the years. But not many that would work inside a missile interceptor.
“If you look at your PC, it has fans, and some of them are liquid-cooled. We don’t have room for that,” said Gary Schott, mission area chief engineer for strategic missiles and defense at Raytheon Missiles & Defense, a Raytheon Technologies business.
Keeping the circuits from overheating was among the big engineering challenges for the team behind the SM-3 Block IIA interceptor, the newest version of a defensive weapon used to defeat short- and intermediate-range ballistic missiles.
The team certainly couldn’t sacrifice processing power or scale back on the sophistication of the software. If anything, they had to cram in more power to process sensor data faster and help the interceptor stay on course and locked onto its target.
So how did they solve the problem? Heat sinks – pieces of metal whose only job is to soak up as much thermal energy as they can. The concept itself is pretty simple, but the twist here was that the engineers had to figure out precisely how many they needed, where to put them and which materials struck the right balance of size, weight and heat capacity.
The process reflected some of the core rules of engineering, Schott said: "No unnecessary parts, everything working as efficiently as possible."
“These missiles are Swiss watches. There’s an incredible amount that’s going on, and all of it has to happen,” said Schott, a systems engineer and software engineer by training. “Whatever we do, it’s only on that missile because it has to be. It’s there for a reason, and it must do its job.”
A fully optimized factory
A space telescope is not an easy thing to build.
It’s an intricate system of sensors and mirrors whose parts have to be placed with nanometer precision. Handling requires extreme caution: Even a small mishap like a cart rolling over a bump can foul things up and set production back.
So when Raytheon Intelligence & Space received a contract from Maxar Technologies for new payloads, engineers saw it as an opportunity to design a fully optimized manufacturing facility. To do that, they turned to what’s known as the “digital twin” methodology.
Using a 3-D scanner, they created a detailed digital replica of the assembly room – right down to the drawers on the tool chest. Then, using modeling and simulation software and the actual specs of the pieces they would assemble, they began configuring the room and designing custom tooling.
“Usually with manufacturing processes, you would do a little trial and error – let’s put this here and hopefully it works. We were able to do all that digitally,” said Madison Dye, a systems engineer who led the “digital twin” effort. “It allowed us to make extremely quick changes and get simulated results to know if that was a path to continue with or not.”
“Normally, manufacturing has to wait until they get the product to take dimensions and build tooling and production aids,” Dye said. “When you have that communication from manufacturing to design, everything improves and everybody has a much larger picture of the product overall, and how we can do the best for our customers.”
A seat that saves lives
The ejection seats on fighter jets are incredibly complex systems.
They control a near-instantaneous sequence of events that includes securing the pilot’s head and limbs, removing the canopy, cueing the catapult, sensing conditions such as velocity, firing the rocket motors and parachuting to the ground.
To engineer all that is a feat in itself. Now try designing one that’s as safe for a 103-pound pilot as it is for a 240-pound pilot.
That’s exactly what the U.S. Air Force wanted, and that is what Collins Aerospace, a business of Raytheon Technologies, has produced. The ACES 5 ejection seat accommodates pilots of many body types – a significant variable in an already complicated equation.
“The range requirements for pilot height and weight are huge, and there are so many safety precautions for the entire flying and ejection sequence that revolve around the seat,” said Kayla Goodrich, a design engineer at Collins Aerospace. “You have to make sure that all of the safety precautions will work for the shortest and tallest person. Like, will the seat eject far enough away for the heaviest person to clear the aircraft?”
One of the biggest obstacles: making it so the ejection force was safe for the smallest pilot but powerful enough to get the largest pilot far enough away from the plane.
The seat’s CKU-5C rocket accomplishes this by adjusting the thrust of the ejection phase based on the pilot’s weight. It also uses a two-stage propulsion system; the first stage propels the seat out of the cockpit, and the second propels the pilot away from the aircraft until it’s safe for the parachute to deploy.
For pilots, the benefits are clear: ACES 5 reduces ejection-related spinal injuries to less than 1 percent. It also reduces overall ejection-related major injuries to less than 5 percent.
A time-saver in designing jet engines
It’s an essential step in designing a jet engine, and, even for experts, a single attempt can take hours.
Estimating an engine design’s real-world weight is an important part of cycle selection – the process of determining how hot an engine should run, how much pressure it produces, and how fast the internal parts should spin to achieve the desired performance.
If the weight estimate is off, everything else could be, too: a heavier-than-actual prediction might lead engineers to believe the aircraft will miss its fuel-efficiency target (and then it’s back to the drawing board), while a lighter-than-actual weight prediction could lead to other challenges.
But if the weight estimate is accurate, it gives engineers a pretty good footing to find what’s known as the “optimal cycle.”
“Thrust, size, weight, cost, maintainability, durability – you want to turn all those metrics green,” said Brian Merry, a system designer in the advanced military group at Pratt & Whitney, a Raytheon Technologies business. “The optimal cycle does that.”
Finding that optimal cycle often takes trial and error – and many recalculations of engine weight, and, in turn, many, many hours.
Merry has written a series of weight-calculating algorithms that allow computers to do the math far faster than a person ever could. They take all the variables into account – the parts, the performance targets – and use a coefficient that determines each factor’s influence on the final answer.
The result: What once took a whole morning or afternoon now happens in a fraction of a second.
“We run tens of thousands of cycles now in the computer, where you wouldn’t be able to do it by hand. You’d spend years and years,” Merry said.
After successful adoption in his group, Merry said, there’s interest in using the method across the company. It would bring a significant savings of time – and a better way to build optimized engines for airframers.
“I’ve always loved a good puzzle with lots of variables. That’s always interesting to me – figuring out what makes it tick,” he said. “This is why I enjoy working on advanced programs. The more advanced it is means there are all kinds of variables and nothing is locked down. You get to change everything and come up with a more optimal solution.”