Unlike commercial aircraft manufacturers who, safe in the knowledge that passenger capacity and fuel economy will always be key, can spend hundreds of millions bringing a new product to market without a confirmed customer at the outset, prime contractors in the defence sector can only push self-funded research and development so far before needing a customer and some neatly defined requirements.

“Do we have to get it to the five-yard line, or the 10-yard-line or the 50-yard line? Because we are not making it [informed by] customer requirements, we are making a concept,” says Richard Sullivan, head of future programs at Northrop Grumman.

401 UAV_2021_0821a

Source: Northrop Grumman

Model 437 is pitched at ‘loyal wingman’-type initiatives

In this instance he is referring to the Model 437, an unmanned concept aircraft built by Northrop’s rapid prototyping business Scaled Composites, but it is a theme he touches on several times throughout the course of our interview.

In the case of the Model 437 – revealed last year – the design is being shaped to meet mission needs for not only the USA, but with an eye also on other international ‘loyal wingman’-type efforts. The latest renderings of the aircraft released by Nothrop show a more streamlined nose over the previous version as the company “optimises the form factor”.

Sullivan sees strong customer interest in a similar design, which marries low cost with “fantastic payload capabilities and fantastic range”, despite a maximum take-off weight of only around 3,850kg (8,500lb). Northrop continues to fly the related Model 401 manned aircraft, but it is clear that, as noted, development can only be taken so far without a customer. (The company’s now-retired Model 355 Firebird is arguably a case in point.)

“We have to be careful to not get too far with any of our designs because if [customers] want it to carry more payload or fly longer, or slower [than the prototype] that changes the wing aspect ratio, the wing area, it changes the propulsion system you pick,” he says.

That guidance can also apply when considering a possible successor to an aircraft that has already been successfully fielded. Take, for instance, the RQ-4 Global Hawk. Originally developed by Ryan Aeronautical, which was acquired by Northrop in 1999, it had its first flight in 1998, and has been in service since 2001. Designed for persistent, wide-area surveillance missions, the jet-powered high-altitude, long-endurance unmanned air vehicle (UAV) has also spawned a maritime variant, the MQ-4C Triton, which arrived in 2018 after a five-year development.

Sullivan thinks both will remain relevant for years to come (in fact, he argues the Triton has the potential to “revolutionise” naval operations), but inevitably Northrop is giving some thought to a successor.

“We are always looking at what the next high-altitude system might look like,” he says. “I think we’ll continue to evaluate high-altitude capability, looking at other potential variants – maybe it doesn’t look exactly like the Global Hawk does today. And we might be working on some new configurations, just to be ready.”

Underpinning any studies are the basic premise that there continues to be “value to endurance and altitude”. But given that the basic design is over two decades old, Northrop is asking, says Sullivan “What would we do today given what we know now? What would we bring forward if the customer asked us tomorrow?”

Aside from the twin building blocks of altitude and endurance, other considerations include payloads, and the power necessary to both run and cool them. While Northrop is watching with interest the development of solar-powered surveillance platforms – “we think they are really neat”, says Sullivan – that appears to be with a degree of skepticism about their utility versus a Global Hawk-type aircraft.

Triton second-c-US Navy

Source: US Navy

MQ-4C Triton is operated by the US Navy

“As we all know, solar power is really limited in how much power you can provide to payloads and other systems. You want to balance that endurance but also having mission-relevant capability,” he says. While he thinks there will be a place for such systems, he questions whether they will be as versatile as more traditional UAVs that operate at a similar altitude.

But Sullivan points out that the “interesting thing” about solar power is that it offers “a clean or carbon-neutral aspect”. Northrop is looking at other powertrain solutions such as hydrogen or hybrid-electric for possible future applications: “All of that’s being evaluated,” he says. Even batteries could offer potential, albeit that Sullivan says they “still have a ways to go” in terms of their energy density.

However, the pursuit of low- or zero-emission technologies raises an interesting question: do environmental concerns matter for a military operator? In that instance, the most important criteria when assessing a system’s effectiveness is surely whether it accomplishes the mission in the most efficient way possible, not how many grams of CO2 it produces.

But Sullivan contends the answer is more nuanced: provided the technology is “mission effective” he sees no reason why it cannot be deployed. And while emission reduction may be one benefit, the fact that such systems are likely to also cut operating costs may be the bigger driver for their adoption, especially in the current climate where the price of jet fuel is at a record high.

“What does that [high fuel price] mean in terms of what operators originally planned in their budgets to complete their annual flight hours? Either they are going to override [their budget] or they are not going to fly as much – which means they are either not training or not doing missions,” points out Sullivan.

Meanwhile, Northrop continues to refine its approach to the rotary-wing segment following the partnership agreement it signed with Leonardo Helicopters last year. “There’s a number of things we are looking at from a cargo and ISR [intelligence, surveillance and reconnaissance] perspective that could leverage that relationship and our increasing knowledge of the AWHero [platform],” says Sullivan. “It helps us guide what the next aircraft may need to look like based on a demand signal from the customer.”

Sullivan says the company is analsying how to approach a future US Navy requirement for a maritime strike helicopter – a replacement for both the Northrop MQ-8C Fire Scout UAV and Sikorsky MH-60R Seahawk manned helicopter – alongside the US Air Force’s future vertical lift ambitions.

Whether anything for the USAF resembles a more traditional rotorcraft – for instance, a derivative of the AW609 tiltrotor – or some other encapsulation of vertical-lift technology remains to be seen and will be guided by – you guessed it – whatever the requirements dictate.

“We’re not trying to bring a platform and say ‘I have a vehicle, tell me what the requirement is’,” he says.

“I think as the requirements mature we’ll start [refining] our assessment of what is the best solution because we want to be prudent with what we are looking at going after. Can we compete? Can we be affordable? And then we’ll make a decision on that.”