With the advancing development of UAVs, muffler systems are moving increasingly into the focus of engine development. It doesn’t matter here whether they are being used to increase performance or purely for sound-volume minimization. 3W-International GmbH recognized this development early on and began developing a series of in-house mufflers.

‘We view ourselves not as a pure engine manufacturer but as a solution provider. That’s why it was important to have the matching muffler in the portfolio for each engine in order to be able to offer a perfectly functioning, complete system to the end customer’, explains Karsten Schudt, managing partner of 3W-International GmbH. Due to close co-operation with leading UAV manufacturers, it was clear early on that muffler systems would meet with a leading role in future.

3W therefore began in 2000 with the development of in-house muffler systems. The first systems were ready for serial production in 2002 and received both the German as well as the patent from the US. 3W mufflers use a type of turbine wheels that are installed permanently in a cylinder. The individual fins mounted on the wheels are queued up in defined angles. In this connection they are arranged in opposed directions depending on the angle. This arrangement smooths the exhaust gas’s sound wave thereby reducing the exhaust-gas sound.

‘Due to in-house development opportunities, we have matched each muffler with the associated engines. That means we offer a broad portfolio of mufflers whereby we can adjust the engines to the customer’s needs’, says Schudt. Special attention should be paid here to the muffler’s volume for the engine. ‘Otherwise the muffler diminishes the engine’s performance. This shows up especially when the muffler is too small, because in these cases excessive pressure from the exhaust gases builds up in front of the actual muffler’, explains Schudt further.

That’s why engine-muffler combinations for each engine are sought that optimally exploit the muffler’s efficiency without having to worry about the engine’s performance diminishing in the process. The calculation here is based on the fact that the muffler’s volume must be 10 to 15 times greater than the cylinders’ stroke volume in order to achieve an optimum muffler effect.

Once the right engine-muffler combination for the customer has been determined, the muffler must be adjusted to the specified spatial dimensions. ‘This can often be a greater challenge than evaluation of the right muffler’, says Schudt, who knows. For this reason, 3W-International GmbH is also offering to produce mufflers according to customer desire. In these cases, the mufflers are adjusted to the specified dimensions and spaces, with efficiency remaining the same.

Each year, 3W-International GmbH sells a variety of muffler systems from in-house production. ‘Our experience enables us to very quickly offer our customers a very functional engine-muffler combination. For the customer, this means saving time and money in his development projects because he receives a finished solution from a single source’, Schudt clarifies. 3W-International therefore assumes that demand for such combinations will increase further in future. Thus the company is preparing itself for continued and new development of muffler systems.


With more than 30 years of experience in designing, manufacturing and testing 2-stroke engines, 3W-International GmbH has developed and patented the newest generation of Heavy Fuel (HF) engines for the Unmanned Aerial Vehicle (UAV) industry.

The quality of 3W-engines consists of several factors. Technical expertise, long-term experience, tradition, and state-of-the-art production are the reasons for one of the highest qualities in the industry. 3W disclaims manufacturing abroad so customers can be sure every engine is German quality.

From R&D, prototyping, purchasing, manufacturing, and calibration to on-time delivery, 3W guarantees constant, permanent quality control. Every manufacturing step is traceable. The employees are personally responsible for fulfilling 3W-quality standards. Component suppliers and partners share those standards and guarantee these quality requirements.

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