X-planes: Are they needed in the new era of drones?

ByMichael Dempsey

Technology Reporter

There's a weird and wonderful jet flying over the US. It has the nose of anteater, parts cannibalised from other planes and a cockpit so far back the pilot depends on a camera to see where he's going.

This contraption, the X-59, might just be the future of air travel.

The X-59's owes its eccentric design to the problem of sonic booms. The shockwave created by a jet breaking the sound barrier restricted Concorde to flights over the sea and barred it from lucrative routes across the US.

Now Nasa is working around that problem using the X-59's elongated snout to flatten supersonic booms into tolerable bumps in the background.

On top of its bizarre appearance the X-59 boasts a remarkable lineage. It's the latest in a series of experimental Nasa aircraft dating back to 1947 and the first plane to break the sound barrier, the Bell X-1.

Peter Coen, a 43-year Nasa veteran who manages the programme, explains the thinking behind 80 years of X-planes. "Our approach is to pick small goals we aim to prove with flight data and we construct an airframe for that one task."

The X-plane philosophy is to "minimise goals, the more goals you have the more expensive it gets." For the X-59 it's about suppressing sonic booms on a budget and nothing else.

In the case of the X-1, flown through the sound barrier in 1947 by the legendary test pilot Chuck Yeager, Nasa knew a .50 calibre bullet travelled faster than the speed of sound. So the stumpy little aircraft was shaped like a bullet with wings added.

A mere 20 years later the X-15 rocket plane, a cylinder with tiny wings dropped from a B-52 bomber, flew to 6.7 times the speed of sound (4,520 mph) and the edge of space, paving the way for heat-resistant materials vital to the Space Shuttle.

Nasa is flying the X-59 in conjunction with community surveys to assess what people think when a supersonic boom is bent by the planes stretched nose and hushed up.

"We want to figure out what level of boom is acceptable to people on a regular basis," says Coen, who reckons his machine will sound "like a car door being closed across the street" when it flies past Mach 1, around 660mph at airline cruising altitude.

With its cockpit and ejector seat taken from a T-38 training jet, its landing gear from an F-16 fighter and engine courtesy of the F-18 this jigsaw of an aircraft was assembled by Lockheed Martin for Nasa.

A camera feeding a screen in front of the pilot relies on instantaneous computer processing to get round the lack of forward vision. It first flew in 2025 and is now breaking the sound barrier over chosen US towns.

But is there still a place for X-plane projects in a world where relatively cheap drones are being rapidly developed - not least in Ukraine's war against Russia.

Even Nasa considered an uncrewed X-59. But drones are not always a cheaper option.

Removing the pilot would have added the cost and complication of certifying a robot jet to fly fast over urban areas.

Plus the X-59 had to be big enough to resemble an airliner punching through the sound barrier, which in turn allowed space for a cockpit.

Nasa is no stranger to drone X-planes. The X-48, a scaled down model of an airliner that blends wing and fuselage to create a single lifting body, flew in 2007.

Small was beautiful for the tiny X-48 with its 20ft wingspan as this kept the programme within budget.

"It's likely that future X-planes will be uncrewed," says Coen, before adding the vital caveats "unless the technology we're researching relates to piloting or if crewing it is more cost-effective".

Guy Gratton, professor of Aircraft Test and Evaluation at Cranfield University, gets frustrated at the suggestion crewed test planes have had their day.

"There's a belief in certain quarters that drones can do everything. In Ukraine they've done amazing things with drones, but if you want to carry people you can't take short-cuts."

Gratton has tested light aircraft and stresses the importance of a human in the loop. "You lose a huge amount without pilots, you miss lessons a pilot would identify, plus it can take four times as many people on the ground to test a drone."

Staff monitoring signals from a drone are an indirect cost that keeps some piloted X-planes relatively affordable.

The UK has flown its own technology testbeds and Chris Yeo was in the pilot's seat of one. The Experimental Aircraft Programme (EAP) flew from Lancashire in 1986 and tried out core systems for the Typhoon fighter.

Yeo acknowledges the EAP's shared heritage with X-planes. "They all research some facet of flight, and demonstrate the design is working correctly. A lot of people say they can do something, but you only know it works when the design has been tested and certified."

Forty years on from Yeo's EAP flights a new UK technology demonstrator is taking shape. It is, says Tony Godbold who runs the project for BAE Systems, "the X-plane of our generation".

This BAE Systems initiative pulls together 100 UK suppliers including Rolls-Royce to test out ideas that might make it into the Global Combat Air Programme (GCAP), a fighter due to fly in the 2030s. The technology demonstrator will borrow engines from the existing Typhoon and fly sometime in 2028.

This has triggered great excitement in the UK's small community of qualified fast jet test pilots. Almost every one, around 14 of them says Godbold, has already tried out this plane on a flight simulator.

For many in the aerospace industry, the human element still matters as much as it did in Yeager's day. "You can model a lot on computers and simulators, but the experience of test pilots is when stuff gets real, we only really learn things when we get their feedback," Godbold admits.

There's a political dimension to such jets too. Godbold says his plane underlines the UK's commitment to GCAP, a joint effort with Italy and Japan. "This proves we are serious in this space."