Member Spotlight: Prismatic Elevates Innovation to the Stratosphere

Tell us about Prismatic.

Prismatic is a subsidiary of BAE Systems and part of their FalconWorks center for advanced air industry research and development. Right now we are principally focused on the design, development and entry to market of the HAPS UAS PHASA-35 platform. The PHASA-35 is a stratospheric, fixed-wing aircraft that’s 35 meters (115 feet) wide and a payload of up to 15 kg (33 pounds). We have been conducting flights since the maiden flight in 2020 and then completing stratospheric flight trials in 2023 and 2024 of our experimental prototype which has effectively proven the concept and the aircraft design. Towards the end of 2024, we completed the build of our next-generation platform, the Block 20 FM3 and we’re aiming to fly that in 2025.

We’re a small company — around 100 people — but we’re able to draw from BAE Systems to access some unique skillsets across aerodynamics, engineering, and beyond. So it really helps that we’re part of a much larger aviation company.

Why is it important for Prismatic to be a HAPS Alliance member?

We’ve been a member for quite some time, and for me it’s important to be a part of the HAPS Alliance. In a cutting-edge market like HAPS, it’s good for everyone that we have a community to talk through the issues such as certification, launch and recovery, and different technological developments. I believe the market will be significant so there’s room for lots of different platform and service providers, so we’re much stronger together as a group and we can support each other’s success. With that — I’d like to highlight the success Aalto had with their Zephyr HAPS vehicle which completed a 13 day flight above Kenya in January – this really extends as a success to the wider HAPS market in proving this is a valid market.   

We support a number of the HAPS Alliance working groups, particularly in areas that we’re interested in. Hopefully we’ll be bringing some real-world use cases and examples where PHASA-35 is doing well in the market and driving the industry forward.

I definitely think that it’s needed now more than ever. We’re coming out of a period where most of the emerging platforms have been stuck in development and not moving into meaningful operational use. Now we’re starting to see stratosphere platforms that can provide a service entering the market, so we need the HAPS Alliance because the pace of technology maturation is going to start accelerating.

Going forward, I’d like to challenge my fellow members of the HAPS Alliance to look at some of the areas which I think have been overlooked in HAPS — in particular, stable launch and recovery sites around the world. We need to have locations that we can launch and recover from — and that could benefit many different platform and service providers. That’s what I’d like to see the HAPS Alliance look at.

What does your newest test flight of the HAPS UAS PHASA-35 mean for the HAPS industry?

In October 2024, we conducted a stratospheric flight and prepared the aircraft for a second mission in just three shifts — a turnaround of only a few days. That’s a significant step forward in the industry — that proven repeatability — in that it can be launched, recovered, overhauled, and relaunched efficiently. This capability aligns closely with military use cases requiring rapid overhauls, payload swaps, and mission reorientation, one of PHASA-35’s unique attributes.

One of the other milestones of the 2024 flight is that we managed to carry a 10 kg (22 lb) payload that was point-loaded — towards the front of the aircraft. That’s a significant step forward for fixed-wing HAPS. We all know that balloons can carry significant weights, and they have great use cases, but the advantage of fixed-wing HAPS is the freedom of navigation that it offers in combination with the 10 kg payload. That’s new.

The flights in 2024 with our prototype platform were only capable of hitting the stratosphere and then coming down again because of the energy storage on the platform. We’ve now developed a new Block 20 platform that can sustain multi-day stratospheric flight. So what that means is that we can offer that 10kg-15kg payload swap but have multi-day operations — and that’s what we’re really aiming for in 2025.

Can you estimate how long the next iteration of the PHASA-35 will be able to fly?

The next platform can sustain itself for a  repeatable 24 hour stratospheric cycles, effectively surviving the night in the stratosphere and then completely recharge its batteries the following day. The duration of the flight for the platform is only a matter of crewing — in other words, how many crews you can put on it, not what the aircraft can do. PHASA-35 has been designed to and has the potential to fly for several months at a time.

One of the other great areas we’re striving for is to use automation so fewer people can crew more platforms. This will bring the overall endurance up on these aircraft.

It could fly higher, but it then becomes a physics trade off because there’s even less air up there, and you have to fly faster to generate enough lift. So the higher you go, the more energy you end up using to maintain that altitude  in the stratosphere. Ensuring the aircraft can sustain a safe operating floor above the troposphere and the adverse weather conditions is the key, rather than simply flying higher.

Is there an approximate target date for the test of the next version?

The typical flying window in the U.S., where we’re operating, is between June and November, so we’re hoping to conduct flights in that window. 

What do you see as the future of the PHASA-35?

I can see from 2026 to start operating limited services for military customers and providing meaningful operational capabilities, with the potential for full entry into service in 2027. Our initial market is military, but we’re also talking to commercial service providers as well.