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Interview: Kimberly Slater of Draper Laboratory Discusses the Challenges of Hypersonic Flight

By Doug Messier
Parabolic Arc
May 20, 2022
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Kimberly Slater (Credit: Draper Laboratory)

by David Bullock
Staff Writer

Parabolic Arc conducted a Q&A with Kimberly Slater, the Commercial and Science Space Lead at Draper Laboratory, about the guidance, navigational and control software she has worked on for Stratolaunch’s Talon-A hypersonic test vehicle.

Tell me a little about yourself, your engineer and career background and how you got to work for Draper.

Right now I currently lead our civil commercial science space work at Draper, but my history before Draper was all in human space flight. My engineering degree is in man machine interface design. And everything I did before Draper was building, developing, testing, and flying scientific experiments on the space shuttle and space station. So, I did everything from design and build to writing software, writing the interface training manuals to the software—the procedure that the astronauts use on orbit—and then I did crew training for both the American and Russian crew for both space station and shuttle and then mission support and then mission control centers in both Moscow and Houston to support the mission. You know that whole ‘Houston we have a problem’ question when things on orbit and any anomaly has happened during that real time fast paced mission support. 

So everything I did back then was looking at how the scientific research we do on space station supports life on Earth. A lot of people are looking out towards the universe to look at other questions, but most of the work I did was Earth focus and human focused. So I came to Draper to look at that perspective of Earth from a variety of standpoints. So one of the first programs I did was a small satellite program. So if you could take whatever research you’re looking at from one-billionth standpoint from space station and move it out to hundreds and now thousands of small satellites what does that look like in terms of our impact on Earth. It means that we could do a whole lot more. So from there I’ve expanded a role in science to commercial programs—Mostly in space but also in suborbital work, much like the Stratolaunch program we are talking about today.

Talon A hypersonic vehicle (Credit: Stratolaunch)

What is the Talon-A Hypersonic Test Vehicle?

So Talon-A is one of three hypersonic test vehicles developed by the private company Stratolaunch. Statolaunch is building a test bed to test for other customers to test their own payloads at hypersonic speed.

So how is it different from other test vehicle?

So it rocket powered. It’s agile. It’s reusable. It also uses the rocket carrier vehicle to get it to altitude before it launches, so it’s a lot lighter and more reusable. And it approaches speeds above Mach-5. Right now the future test vehicles will increase the speed, but it is really intended to be a reusable, persistent, frequently flying test vehicle for customers payloads.

Talon A hypersonic test bed. (Credit: Stratolaunch)

What is the guidance software you are working on for the vehicle?

Draper has a long history developing guidance, navigation and control software. We’ve sort of created the field of it years ago, when we did all the work for Apollo. Since then, Draper’s been a guidance, navigation and control partner on every major NASA mission and a number of major commercial missions, as well. We do work with much of the major space primes. For Stratolaunch in particular, its a perfect Draper program, because Draper is a non-for-profit and the work we do needs to be new, exciting and pushing the boundaries on these new technologies. We don’t do work to do the same things a thousand times and do it well. We do it to do a new thing better. So we’re always looking for new engineering challenges and Talon-A is one of those. So we’ve got a history of doing guidance, navigation and control for hypersonic vehicles for the government, what we’re doing here is taking a new exciting, slender. fast paced vehicle with really challenging requirements.

At hypersonic speeds you’ve got fuel sloshing, you’ve got thermal constraints, you’ve got drag, you’ve got controllability of the vehicle. So it takes the decades of experience we have in guidance, navigation and control and in this case the controls are probably the most exciting part of it and applying it to something new and more challenging. So for Draper it’s not just looking at a vehicle and helping them drive it, it’s building on all the experience we have and applying to another exciting new vehicle and being able to support that customer in their own mission.

Stratolaunch completed its fifth test flight of Roc, on May 4, 2022. The flight debuted a new pylon that was integrated to the aircraft center wing. The pylon will be used to carry and release Talon hypersonic vehicles.

How is the guidance software integrated into the rest of the vehicle?

So in general, this a very traditional Draper role. We design the guidance, navigation, and control software and it’s akin to be it a self driving car. You build the car. The software is not developed independent of the car. It is developed in concert with it, during the entire design process. So we work very closely with our customers. As they’re designing, building, testing their vehicle, we are designing, building and testing the guidance, navigation and control software in parallel. During that process we have touch points. We’ll deliver preliminary versions of the software and do integrated testing to make sure that their development and ours are heading in the same direction.

Talon A hypersonic aircraft flight profile. (Credit: Stratolaunch)

For example, we create really well defined simulation environments so that as we’re building and testing, we doing constant and frequent and multiple simulations to make sure that it will integrate well into the vehicle. So by the time that we do integrated testing with the customer software and ours, there are very few surprises. It usually runs real smoothly once we start doing the integrated testing that because we put so much effort in the simulation part in the earlier stages. So, as we are going through their development and we are developing things like their fuel tank and we’re looking at their continued development of the fuel tank and what that slosh looks like, we’ll keep building those parameters into our own simulations and running and rerunning them as we develop. So by the time we are ready for a flight test we’re really really ready. 

How would Stratolaunch use this software?

We built this customized for Stratolaunch. It empowers Stratolaunch to go fly this vehicle. We’ll be here in full force in the beginning during the development. We’ll be a partner during the test and flight, but our role becomes less and less over time. As they go through their first and second test flight, our role becomes tweaking parameters and making sure everything’s performing well, and then watching them [fly.] If they fly that vehicle a thousand times again without us, we’ll have accomplished our job.

What we’re looking for next is as they’ve built the next vehicle we’ll take what we’ve done on this mission and tweak it for the next one. So, the next vehicle is going to be different, but there will be a lot of similarities. They be things we’ve learn in the development of this software that will put us farther ahead. So by the time they’re developing the next vehicle we’re ready to support them on that. And I think from the customer standpoint, what that looks like is even for Talon-A, Stratolaunch was able to get through their entire design development, build and test process faster with Draper as a partner—faster and more safely with robust software that is more reliable.

For the next vehicle, this would also be true. And we’re starting out even closer with the work we’ve done on Talon-A. The very long answer is the software isn’t something you can take and just back fit into a new vehicle. The learning from it would allow us to develop software for newer vehicles, but it is really customized for this specific solution. 

Why is this work important for hypersonic weapons development? In relation to China and Russia?

It is allowing customers and a lot of government customers to test payloads and solutions on a reusable, reliable test vehicle. So a customer can go and develop whatever hypersonic solution they want and Talon-A gives them the ability to test it frequently and robustly. 

What work would you like to do in the future?

For me personally, I really enjoy using the technology solutions we have for Earth-focused climate work. That is one of my main areas of focus. 

If there is one common thread among everybody at Draper, and I mean management, engineers, accountants, is that we’re all excited by doing something meaningful and new. So Talon-A is one of the things that we’re most excited things we’re doing and we’re thrilled and we can’t wait to watch their flight later this year. But what we want to do next is whatever’s is coming next—whatever new thing we have never yet imagined.

In Stratolaunch’s case it will be a newer, faster, better vehicle, because the next one they build will be an improvement upon Talon-A. That’s just human nature—to innovate to make something more faster more exciting, more reliable. Maybe bigger. I’m not sure of what their next vehicle requirements are. But for Draper, what we’re looking for is what hasn’t been accomplished yet—what is the next big challenge. And certainly China and Russia are foremost in those in how we’re protecting our national security, by developing the most important technology to support our own country. To support the United States.

Is there anything you’d like to add?

Hypersonics is intimidating. Hypersonic the word itself is intimidating and equally exciting, but because of the environmental challenges I think it’s that much more important that you get an existing new, talented team that Stratolaunch has an get it coupled with the deep experience Draper has to do new and exciting things. 

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