By Michael Kahn, Supantha Mukherjee and Tom Balmforth
PRAGUE/STOCKHOLM/LONDON, April 7 (Reuters) - Specialist mini jet engine makers across Europe are ramping up production and investment to head off a looming supply shortage that threatens to hold back Ukraine's rapid deep-strike drone programme at a critical stage of the war with Russia.
Mini turbojet drones are faster than propeller-driven models and far cheaper than cruise missiles, allowing Ukraine to strike deep inside Russian-held territory while competing with more advanced Russian systems such as the Geran-5.
But a shortage of the mini engines is raising concerns about a potential supply crunch for deep-strike drones, more than a dozen arms experts, companies and government officials told Reuters.
"Europe has a massive bottleneck in mini-jet engine production," said Fabian Hoffmann, senior research fellow at the Norwegian Defence University College, adding the sector was also key to helping reduce Europe's reliance on the United States.
A Ukrainian defence industry source, speaking on condition of anonymity, said the mini-engine shortage was "probably the main factor limiting the number of missile drones produced," describing it as a "big problem for our missile programme".
Maria Popova, COO of the Ukrainian Council of Defence Industry, the biggest association of private weapons manufacturers, agreed there was a bottleneck of turbojets for drones as well as the materials needed to build them.
"Supply remains constrained both globally and, more acutely, within Ukraine," she said.
Oleksandr Kamyshin, Ukrainian President Volodymyr Zelenskiy's arms expert and defence industry adviser, declined to comment on whether the shortage was having an impact.
'STRETCHED TO THE LIMITS'
Deep-strike drones have delivered morale-boosting results for Kyiv at a time when allies are distracted by war in the Middle East and Russia is grinding out gains on the ground.
As well as long-range strike drones, mini jet engines power loitering munitions and missile interceptors. With few European manufacturers producing them at scale before Russia's 2022 invasion of Ukraine, ramping up output has proved difficult.
Czech-based PBS Group, one of the few established producers at the start of the war, has increased production five-fold since 2023 and expects that figure to reach eight-fold by the end of this year as Ukrainian demand surges.
"Our capacities are stretched to the limits," PBS Chief Global Officer Stanislav Lisner told Reuters. "We're investing heavily to expand production," he said, without giving a figure.
PBS has signed an agreement to develop a new engine through a joint venture with Ukraine's Ivchenko-Progress, as part of talks that could include co-production.
PBS's turbojet engines power deep-strike drones such as the Palianytsia, which can reach speeds of up to 900 kilometres per hour (559 miles per hour). That compares with about 185 kph for propeller-driven Shahed drones used by Russia, at a cost military experts say is far below the $1 million-plus price tag for Western cruise missiles.
They compete with Russia's jet-powered Geran-5 drones, which can fly close to 1,000 km (621 miles) at speeds of up to 600 kph and carry payloads of about 90 kilograms (198 pounds).
TINY ENGINES, BIG IMPACT
Mini turbojet engines, typically less than 30 centimetres in diameter, are built from lightweight materials such as titanium alloys, often using 3D-printed components, and generate enough thrust to carry explosive payloads over long distances.
While Russia sources some engines from China, according to European security officials and documents, Ukraine relies on a small group of European suppliers, including PBS, Germany's JetCat and Netherlands-based Destinus.
"We see increasing demands for these weapons from Ukraine," said Adam Vysocky, head of Czech-based turbojet engine maker ZofiTech, which develops advanced systems including the deep-strike Narwhal drone and Nightray platform.
ZofiTech delivers nearly all the roughly 200 engines it produces each month to Ukraine, and expects demand "to reach thousands in the coming months".
Large aerospace engine manufacturers such as GE Aerospace and Rolls-Royce have largely stayed out of the segment, focusing instead on more profitable fighter-jet engines.
"There are only a few companies that are developing these jet engines, and because they are expensive to make the companies will not really start manufacturing them until there's a large government order," said Dominic Surano, director of special projects at defence tech firm Nordic Air Defence.
"That constrains the supply chain."
Some Ukrainian drone makers are working on in-house engine development to reduce dependence on suppliers, but production remains limited. Ukrainian engineers are also testing a low-cost pulsejet engine, unveiled in December and known as Hrim-17, aimed at interceptor drones.
"It is peanuts compared to what Ukraine needs," said Estonian defence investor Ragnar Sass.
DRONE JET ENGINE MARKET 'VERY FAST, VERY HECTIC'
PBS plans to double output at its Czech facility over the next two years as manufacturers expand production lines, hire workers and form partnerships to meet demand, Lisner said. About 25% of PBS deliveries go to Ukraine.
New players are also entering the market.
In February, German drone maker Quantum Systems unveiled a new jet-powered drone developed with Airbus. Nordic Air Defence said it is looking to partner with a stealth startup developing drone motors from scratch.
Czech defence group CSG, which went public in January at a valuation of about $35 billion, is expanding into these jet engines after acquiring Serbian manufacturer Must Solutions in November.
Pavel Cechal, who leads CSG's jet-engine division, said the company aims to produce about 1,000 turbojet engines in 2026, mainly for deep-strike drones with ranges of 400 to 600 km. About 35% of output is expected to go to Ukraine.
"This market is at the moment very fast and very hectic," Cechal said. "Because all the defence companies see a huge potential in that segment."