SOLO 2625-02i NEO Silent: Self-Launch Engine Without The Shake

The Problem with Sailplane Engines

Sailplanes are different from regular airplanes. They float on warm air currents for hours without power. When sailplanes need an engine, it has to be light enough not to slow them down, small enough to hide away, and quiet enough not to ruin the flying experience. For a long time, the SOLO 2625-02i engine worked fine for this job. But when Jonker Sailplanes installed it in their newest high-performance sailplanes, something unexpected happened. The engine vibrated too much. Pilots felt this shaking during long flights. The vibrations also caused parts to wear out faster than they should. The company tried the normal fixes - better mounts and padding around the engine. Nothing worked. The real problem was inside the engine design itself, not outside. So instead of giving up, Jonker and SOLO decided to rebuild the engine from scratch. They worked together for three years to get it right.

The result is the SOLO 2625-02i NEO Silent. The key idea is simple but clever - add a special part inside the engine called a balancing shaft that stops vibrations before they even start.

How It Actually Works

Most two-stroke engines shake more than four-stroke engines. When the engine's piston moves up and down thousands of times per minute, it creates vibrations. These vibrations spread through the whole airplane. The solution is to add a balancing shaft that spins in the opposite direction at just the right speed. Think of it like two hands clapping against each other - when they're perfectly timed, the motion cancels out. That's what happens with the engine vibrations. An opposite force fights back against the natural shaking.

The hard part was fitting this new balancing shaft into the tight space inside the SOLO engine without making it heavier or less reliable. The companies spent almost two years getting the gear system right. They tested it many times and found problems they had to fix. By mid-2025, after lots of changes and improvements, the design finally worked perfectly. Then production could start.

Making Engines Now

In mid-2025, the design was complete and ready for real production. SOLO started making engines in March 2026. Today, they build four engines every single week. Jonker Sailplanes ordered 50 engines right away and paid a lot of money in advance. This shows they truly believe in the product and want to supply their customers without delays.

The engine goes into two types of sailplanes right now - the JS2 Revenant and the JS5 Rey. In the future, more sailplane models will use it. The engine produces 50 kilowatts of power (that's 64 horsepower). It can run for about one and a half hours straight. This gives pilots enough time to climb to safe altitudes and find thermal air currents. They don't need another plane to tow them anymore.

Better Flying Experience

The engine performs very well. It climbs at about three meters per second, even when the plane is fully loaded. It uses fuel efficiently because it has electronic fuel injection - a modern fuel system. Water cooling keeps the engine running smoothly at any altitude. The design has two spark plugs for extra safety and reliability.

Pilots notice the real difference immediately. The new engine shakes much less and makes way less noise than the old one. Mechanics and ground crew appreciate it too. Engine parts wear down more slowly, which means less maintenance and fewer repairs. The plane stays in better condition for longer.

Why This Matters

Designing special engines for sailplanes is difficult. Only a few companies in the world buy these engines, so making them doesn't make much money. Getting government approval for a new aircraft engine takes a very long time and has many strict rules. The three-year project shows serious dedication to solving a real problem that affected many pilots and planes. Most other engine manufacturers either ignored the vibration issue or just tried to fix it with better mounting systems. Jonker and SOLO went much further - they redesigned the engine itself to eliminate the problem at the source. It was harder work, but it created a much better solution.