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Technology: DESCENT Modeling Technology
Agency: Army Research Laboratory
The Army Research Laboratory (ARL) has created software designed to determine the worst case scenario when it comes to rotary aircraft (see: helicopters) in order to improve sustainability and help pilots to live through crashes. So how does it work? So glad you asked.
What is it?
“Descent is ARL’s code for modeling the flight and the landing or impact of the helicopter that loses some or all of its main rotor power, either through the pilot’s choice, in order to correct an uncontrollable flight, or because of system damage that causes the rotor to lose power,” explains Andrew Drysdale, an aerospace engineer at Army Research Laboratory.
He and his colleague, Dr. Matthew Floros, worked directly on this technology in order to improve military operations.
“What descent is meant to do is basically find the conditions where it’s safe to do that type of landing and then what conditions it’s not,” Dr. Floros explains.
In order to do that, they have to put the helicopters to the ultimate test.
What does that mean?
So basically, this is an emergency-land-and-not-kill-us-all hypothetical scenario generator. Using computer software and technology, researchers are able to figure out the most likely case for vehicle – and occupant – survivability when the worst should happen. And by the worst, I mean crash landing.
“We’re trying to see whether or not a safe landing is possible for, you know, whatever the mission requirements are,” Andrew explains. That means finding out what would not be a safe landing. Going through the list of “what we don’t want to have happen” is no small task.
This is where DESCENT comes in.
What does it do?
DESCENT results dictate how fast, and at what angle, the helicopter crashes. Then they run that simulation and the software measures the forces experienced by the ocupants in the vehicle (the demonstration I saw had two occupants). The final step is to use that information to predict injury levels, and decide if we can try to improve the outcome by altering how DESCENT evaluates solutions.
It uses a simple aerodynamics model and 2D rigid body dynamics, Andrew tells me. The optimization algorithm that’s part of the code will iteratively score the solution – which is the maneuver – and it tries to find a better one based on conditions and priorities or goals set by the user.
“So what you end up with is the best or nearly the best possible outcome for landing a helicopter that has severe power loss,” Andrew says.
This technology has the room to grow as well. “Right now we’re in a big program where they’re trying to replace all of the joint services rotorcraft over the next 10 to 20 years,” Dr. Floros says. “As new rotorcraft are being developed, they [will] need some way to assess survivability of those. So [DESECENT] can be used to improve future ones.”
How can this help?
Look, nobody wants to be in a crashing helicopter. It’s what you call a less than ideal circumstance. But it does happen. Stuff breaks. Aircraft gets attacked. Sometimes things go wrong.
And when it does, knowing the best outcome during a worst-case-scenario can be a huge benefit. Life saving, even.
It’s also easy to use. DESCENT is a desktop tool that can evaluate the worst of scenarios before they happen with surprising simplicity. A single person with a relatively small amount of input can produce these somewhat complex survivability calculations with fairly minimal effort. The best part is that the software was designed that way. They didn’t want it to be too complicated. They just wanted it to work.
And it does.
“One thing that happens is that we get a good view of say, what the envelope of possible outcomes might be, so we’re at least aware of them,” Andrew explains. “In order to make the more positive outcomes more likely, or at least to be able to address the negative ones, you have to be aware of what’s possible.”
While this technology doesn’t help the pilot directly, Dr. Floros points out, it does help the military in their assessment activities.
“They can determine what the risks are for various missions, and then that scales up into overall operations and mission planning.”
“We have a lot of flexibility to investigate not just the optimal outcome, but various types of sub-optimal outcomes,” Andrew points out, “either due to piloting technique error or further limitations on the helicopter, such as a jammed control rod or say some rotor damage.”
They’re also working on developing an ability to look at occupant loading, he says. “We can coax the model to find impact conditions that are most conducive to occupant survivability and not just vehicle survivability.”
Okay, so it’s not the Kobayashi Maru, but that’s a good thing. When it comes to military research, knowing what you’re possibly (or probably) up against can be a huge game changer.
“It fills a very specific need,” Dr. Floros points out. “Only the military has a need for such a thing. Nobody really needs to know what the effects of ballistic impacts are, except people who get shot at. You know, it’s a specific tool to address a very specific need.”
I think the most impressive thing about this can be summed up by something Andrew Drysdale said to me.
“It’s the applicability of the code to kind of touch a wide range of questions that people might have about rotor craft and how they’re operated. How they might crash-land most safely I think. I think there’s going to be a lot of questions in the near future that DESCENT will be able to have input. To me, that is the most impressive part of it.”
I asked Andrew if he owned any rotary aircraft of his own (more of the remote-controlled variety). Humorously, he said that he didn’t because he can’t keep from crashing them.
Looks like DESCENT is something that can be used in more than one capacity, eh?
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Jessica L. Tozer is a blogger for DoDLive and Armed With Science. She is an Army veteran and an avid science fiction fan, both of which contribute to her enthusiasm for technology in the military.
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