The future of mobility is electric. Electric cars and electric ships are no longer a vision of the future, but reality. But aviation is lagging behind: despite being responsible for millions of tons of CO2 emissions. The International Aviation Organization (ICAO) is calling for air traffic to grow in a climate-neutral way from 2020 and for emissions to be halved by 2050.

We are developing the ELFIN - the world's first hybrid-electric, series-produced sports aircraft - and are thus ushering in a new era in aviation.

Our innovative drives, optimized aerodynamics and carbon manufacturing technologies enable purely electric flights of up to a sensational five hours – CO₂ - free and extremely quiet.

Based on our technology, we are developing the unique “two-in-one” light aircraft elfin.20 as well as the two-seater remote sensing aircraft for civil use (RS.120/130, e.g. environmental and climate monitoring, disaster protection and research).

Our team brings 40 years of experience in aviation - shaped by Dr. Reiner Stemme, the pioneer of the legendary STEMME S10 aircraft . The high-performance motor glider revolutionized the industry in 1990 by closing the gap between motor and gliding for the first time. It set new standards with world records such as gliding distances of up to 2400 km and overflights of Mount Everest. Today, over 300 of these aircraft from Reiner Stemme's former company are in use worldwide.

technology carrier and innovation pioneer ELFIN

Now we are revolutionizing aviation once again. With our technology carrier ELFIN, we are defining a new class of aircraft (electrically powered hybrid motor gliders) and paving the way for sustainable and future-oriented aviation.

We have already started building the prototype. The first flight of the elfin.20 will take place in the fourth quarter of this year, followed by certification and delivery of the first aircraft in 2026. We have already received the first binding orders from international customers, some of which have already received a down payment.

Picture left: Stemme S10 from 1990 – still in production, > 300 aircraft currently in service worldwide

Picture right: elfin.20 prototype

Prototype production in our production hall in Schönhagen near Berlin

Product 1 – elfin.20: The two-in-one aircraft

A unique product for gliding and motor flight: the first with electric-hybrid propulsion, closing the gap between these two markets.

The elfin.20 is a high-performance, electro-hybrid side-by-side motor glider in the FAI 20m class for touring and sport flying. The first flight is planned for 2025, with delivery starting in 2026.

elfin.20: Autonomous in the air and on the ground. Freedom. Enjoy as a couple

The unique selling point of elfin.20 is a propeller system, developed by Reiner Stemme and integrated into the aircraft's contours. It can be activated by the pilot within three seconds to achieve full thrust. This allows the aircraft to take off with 65 kW of electrical power and reach a cruising speed of up to 200 km/h.

During flight, the system can be switched to gliding mode. The propeller is folded in just three seconds. Glider pilots can then fly distances of over 1,000 km and reach an average speed of more than 200 km/h.

When the weather deteriorates, the unique selling point of our elfin.20 comes into its own: it can switch to full engine power in three seconds and there is no need to forego further flight. The old dream of autonomous gliding and touring thus becomes reality: power when needed - gliding whenever possible.

With electric propulsion, we will achieve a pure flight time of two hours in 2025 and 4-5 hours in the next few years at a cruising speed of 130 km/h.

For longer ranges, we can retrofit a 30 kW Range Extender, consisting of a Wankel engine and generator. This consumes just five liters of diesel per 100 km compared to conventional 15 to 20 liters of aviation fuel.

Autonomous flying also requires autonomous handling on the ground: a two-track, electrically retractable landing gear makes take-off and landing independent, even at commercial airports. The wings with a span of 20 meters can be folded down to a hangar width of 10 meters by just one person in less than five minutes , or swung completely over the fuselage.

Safety is our top priority – both for our customers and for us. As the first company to do so, we offer an EASA CS22-certified "Ballistic Rescue System" for this aircraft class. This safety system can save the elfin.20 along with its occupants in emergencies.

Product 2 – RS.120/130 remote sensing aircraft

The light remote sensing aircraft RS.120 for manned operation and RS130 for unmanned operation are derivatives of our technology carrier ELFIN. As an aircraft platform, they can be upgraded for remote sensing tasks with up to 250 kg of sensor and communication equipment to a maximum take-off weight of 1200 kg.

The aircraft is equipped with an extremely quiet 5-blade constant-speed propeller and is almost inaudible at an altitude of 300 m. There are no infrared emissions during electrical operation (an advantage for critical areas of operation) and no CO2 emissions are generated . The new range extender technology offers a service life of eight hours with two crew members (RS.120) or 25 hours unmanned (RS.130). The procurement costs and operating costs are a fraction of those of comparable helicopters.

Our market target is the replacement of light helicopters that do not require landing outside an airfield during their mission.

Examples of applications include sports observation, area reconnaissance or long-range observation.

Product 1 – elfin.20: The two-in-one aircraft

A unique product for gliding and motor flight: the first with electric-hybrid propulsion, closing the gap between these two markets.

The elfin.20 is a high-performance, electro-hybrid side-by-side motor glider in the FAI 20m class for touring and sport flying. The first flight is planned for 2025, with delivery starting in 2026.

elfin.20: Autonomous in the air and on the ground. Freedom. Enjoy as a couple

The unique selling point of elfin.20 is a propeller system, developed by Reiner Stemme and integrated into the aircraft's contours. It can be activated by the pilot within three seconds to achieve full thrust. This allows the aircraft to take off with 65 kW of electrical power and reach a cruising speed of up to 200 km/h.

During flight, the system can be switched to gliding mode. The propeller is folded in just three seconds. Glider pilots can then fly distances of over 1,000 km and reach an average speed of more than 200 km/h.

When the weather deteriorates, the unique selling point of our elfin.20 comes into its own: it can switch to full engine power in three seconds and there is no need to forego further flight. The old dream of autonomous gliding and touring thus becomes reality: power when needed - gliding whenever possible.

With electric propulsion, we will achieve a pure flight time of two hours in 2025 and 4-5 hours in the next few years at a cruising speed of 130 km/h.

For longer ranges, we can retrofit a 30 kW Range Extender, consisting of a Wankel engine and generator. This consumes just five liters of diesel per 100 km compared to conventional 15 to 20 liters of aviation fuel.

Autonomous flying also requires autonomous handling on the ground: a two-track, electrically retractable landing gear makes take-off and landing independent, even at commercial airports. The wings with a span of 20 meters can be folded down to a hangar width of 10 meters by just one person in less than five minutes , or swung completely over the fuselage.

Safety is our top priority – both for our customers and for us. As the first company to do so, we offer an EASA CS22-certified "Ballistic Rescue System" for this aircraft class. This safety system can save the elfin.20 along with its occupants in emergencies.

Product 2 – RS.120/130 remote sensing aircraft

The light remote sensing aircraft RS.120 for manned operation and RS130 for unmanned operation are derivatives of our technology carrier ELFIN. As an aircraft platform, they can be upgraded for remote sensing tasks with up to 250 kg of sensor and communication equipment to a maximum take-off weight of 1200 kg.

The aircraft is equipped with an extremely quiet 5-blade constant-speed propeller and is almost inaudible at an altitude of 300 m. There are no infrared emissions during electrical operation (an advantage for critical areas of operation) and no CO2 emissions are generated . The new range extender technology offers a service life of eight hours with two crew members (RS.120) or 25 hours unmanned (RS.130). The procurement costs and operating costs are a fraction of those of comparable helicopters.

Our market target is the replacement of light helicopters that do not require landing outside an airfield during their mission.

Examples of applications include sports observation, area reconnaissance or long-range observation.

RS.120/130 remote sensing system

The basis of our innovation is the ELFIN technology carrier , which incorporates our know-how from years of experience - from the first visionary idea to certification. ELFIN combines several groundbreaking technologies that make this aircraft type unique:

• Cell made of carbon OoA prepreg technology: This new construction reduces the mass by 25%, with the same or even higher strength values and comparatively low production costs.
• Reiner Stemme Foldable propeller: Unique concept that allows seamless transition between motor and glider flight.
• Aerodynamic design: Extremely low-drag fuselage and high-stretched wings for significantly more energy-efficient flight compared to conventional aircraft
• Total rescue system: Ensures maximum safety and is implemented for the first time in this aircraft class.
• Modular high-performance batteries: The batteries are of the latest design and can be easily replaced.
• Electric hybrid drive: A state-of-the-art and lightweight Wankel engine offers optional extreme range and long flight time.
• Folding-rotating wing: Enables space-saving and uncomplicated handling on the ground, saves a lot of hangar space.

Market 1 – Touring & Sport

Our two-in-one aircraft elfin.20 is aimed equally at private motor and glider pilots:

• Owner communities and clubs with glider pilots and/or motor pilots.
• Flight schools with advanced training: Advantages are low maintenance and operating costs, simple and safe operation and sustainability.
• Individual, demanding glider pilots who are looking for the high gliding performance of the FAI 20m class combined with the independence and safety of electric start.
• Motor pilots who are tired of flying from A to B and for whom gliding has previously been associated with too much inconvenience and even risk.
• Athletes who started with paragliding or ultralight aircraft and can reach new horizons with elfin.
• American pilots are allowed to fly elfin.20 - unlike motor aircraft - without a medical examination. A big market!
• European sport pilots are facing massive environmental protection-related restrictions – the elfin.20 offers the alternative.

There are more than 100.000 two-seater, conventionally powered aircraft in various classes in use worldwide - powered by everything from vintage engines to modern combustion engines . Around 2.300 aircraft are produced for general aviation every year worldwide. The market is growing steadily and electrically powered models are on the rise.

20.000 single and two-seater gliders in use worldwide - from vintage to modern. Currently, around 200 new gliders are delivered every year , the majority of which are produced by German manufacturers.

This is where we come in: In the luxury class, we offer the elfin.20 Two-in-One, a product for both segments that offers top performance without compromise in both disciplines and comes with new features such as a safety rescue system. As a pioneer of emission-free aviation, we are also actively contributing to climate protection.

We will sell 1.000 elfin.20 aircraft over the next 20 years, with total sales of €500 million, including at least 50 per year from 2029, starting in 2026.

The starting price is €295.000 net, plus €20-30.000 for the battery. With additional options, the purchase price reaches an average of €360.000.

Market 2 - Remote Sensing

The RS.120 and RS.130 are the first remote sensing aircraft with electric hybrid propulsion, specifically designed for airborne remote sensing, opening up new market segments. They are an ideal complement to light helicopters and fixed-wing aircraft. There are currently more than 10.000 regional remote sensing systems in operation, based on fixed-wing aircraft (up to 3 tonnes) and helicopters.

They are an ideal complement to light helicopters:

• Almost no pollutant and noise emissions in electric operation.
• Flight times and ranges can be more than doubled compared to light helicopters with the help of the range extender.
• The direct operating costs of electric flight are only a fraction of the costs of competing products.

Artificial Intelligence (AI) plays a central role in the development and system integration of Optional Piloted Aerial Vehicles (OPVs). It enables flexible control and makes OPVs efficient and safe for use both with and without a pilot. The main applications of AI in this area are:

• Autonomous control and navigation
• decision-making for planning and mission execution
• Human/Machine Communication and Collaboration and Mission Coordination
• data analysis
• security and cybersecurity

By integrating AI, our remote sensing aircraft will also become safer, more effective and expand their range of applications.

Areas of application for the RS.120 and RS.130:

• Environmental protection: Pollution of air, land and sea - Illegal waste disposal - Urban sprawl - Renaturation
• Natural Resources: Agriculture - Forestry - Fisheries - Mining - Oil/Gas/Other
• Geography - Research & Science: GIS applications (Geographic Information Systems) - Specific sensor technology, e.g. detection of underground structures
• Disaster management: forest fires - floods - earthquakes - infrastructure and industrial accidents - search and rescue operations
• Security/Sovereign Tasks: Monitoring of mass events - Special operations - Land, coastal and sea patrols - Infrastructure and industrial complex surveillance - Smuggling and piracy

There are different procurement and operating organizations behind this:

• NGOs such as Greenpeace, Wildlife, UN organizations/projects, government organizations
• Commercial remote sensing for pipeline, mining, infrastructure monitoring
• research institutes, universities (e.g. ARA Airborne Research Australia)

We maintain ongoing contact with authorities and organizations. We have carried out environmental research with Greenpeace and we have carried out measurements in the Mount Everest region with the German Aerospace Center (DLR).

With the RS.120/130, we have an exciting market ahead of us in which we already have a lot of experience. In our business planning, we have set a turnover of 30 million euros for 2029 and the following years. We will start marketing with the presentation of a prototype at the end of 2026 and the launch at the Paris Airshow in 2027.

STEMME S10VTX remote sensing on Mount Everest

Competition - Touring & Sports Observation

Our competitors:

Arcus (left): Tandem glider 20m FAI class, auxiliary drive, single main wheel undercarriage, type approval, 400 units delivered since 2009. Net retail price 250k€ + options.

Aquila 211 (right): Two-seater light motor aircraft, LSA certification, 300 units delivered since 2002. Net retail price 260k€ + options.

These two products are typical of the competition. They can only be used in their respective market segments and represent a high-quality development of earlier versions - the classic model update.

However, they are not a direct competitor to the innovation of the two-in-one elfin.20. The elfin.20 achieves or exceeds the performance of both models. The higher procurement costs of the elfin.20 are more than compensated by its unique features (USPs). We are currently not aware of any development projects comparable to the elfin.20.

Competition - Remote Sensing

The remote sensing market is currently dominated by military developments from the USA and Israel as well as intensive activities from Turkey, China and Russia.

The PATROLLER from SAFRAN with the STEMME Airframe is the only relevant development in Europe in our class.

Our focus is on safety, environmental protection and climate research. Typical sensor platforms are aircraft in use today such as the Cessna 206 or mid-range helicopters. None of these systems have been developed for the specific tasks of remote sensing; the costs are correspondingly high and the results poor.

Cessna 206 | Mid-range helicopter

With the RS.120Whisper/130 we offer better and more cost-effective platforms and are also climate neutral.

Currently and in the coming years, we do not see any direct competition for our products - electrically powered aircraft with range extenders. This is because the focus of the major players is on the military market.

Aircraft construction is multidisciplinary. We concentrate on system competence from market and technology to production and service. In production, the focus is on final assembly, supported by proven, competent suppliers for the components. This approach guarantees flexibility and low fixed costs.

The aircraft of elfin.aero GmbH are designed for the international market and receive the corresponding approvals from the aviation authorities EASA (Europe) and FAA (USA).

The elfin.20 marketing strategy is based on the worldwide recognition of the “ STEMME ” brand with more than 300 sales of the STEMME S10.

Our customers come from all over the world to our company location at Schönhagen airfield for test flights, conclude purchase contracts here and receive their instructions.

In the initial phase, we are concentrating on digital advertising (web, social media) and publications in relevant specialist magazines. The elfin.aero website offers a digital configurator with which interested parties can pre-configure their elfin.20.

The announcement of the first flight will trigger a wave of requests for test flights. We expect orders for over 50 units by the end of 2026.

From 2027, we will also deploy demonstrators on roadshows in Europe and the USA.

Relevant trade fairs for elfin.20 are the AERO in Friedrichshafen for Europe and Oskosh in the USA. For the remote sensing aircraft RS.120/130, it is the ILA in Berlin, the Paris Airshow with its global reach and the Dubai Airshow for the Middle East.

The US market is a special case, where we expect 50% of sales. Elfin.aero will set up a branch here for sales and service.

For the RS.120/130 remote sensing aircraft, elfin.aero GmbH produces the platform, which is then sold to selected system providers. They implement the sensors and sell the complete system to their end customers. The marketing and sales strategy here therefore focuses on expanding close cooperation with system providers, such as the sister company ReinerStemme.aero GmbH.

From 2026, we will increase production to 50 aircraft per year (from 2028/29). An additional business area will be service, including training, support, transfers, maintenance and repairs.

Reiner Stemme decided over 40 years ago to develop a unique glider-motor aircraft. The STEMME S10 has since become a legend. A network of experts, made up of young engineers at the time , formed around Reiner Stemme, who are still connected to him today and are the key to the success story. Together they can look back on numerous world records with their aircraft and international awards.

1984, Reiner Stemme's first company, STEMME GmbH , developed and launched the S10 - over 300 units have been delivered so far. Further developments such as the S12 are still in production. The airframe for the SAFRAN surveillance aircraft PATROLLER was also developed from this, also in production. Other derivatives for remote sensing were developed and put into flight, such as the Q01 for Qatar Airforce.

We already have the first international customer orders (some with advance payments) and purchase options for the elfin.20. We are planning the first deliveries for 2026.

The proceeds from the current financing round will be used for the construction of the elfin.20 prototype and the planned first flight as well as the type certification. We are planning a budget of 2 million euros. This includes personnel costs, external engineering services, materials and operating costs.

Further round of financing is planned for 2025. It is intended to cover the phase up to the start of production in 2026 and will again exceed 2 million euros. We assume that part of the amount will be covered by funding from the state of Brandenburg or KfW funds.

Unique technology with strong unique selling points: Our aircraft are unique in their range of applications and their characteristics – we have developed the world's first light aircraft with electric hybrid propulsion

It is a sustainable investment for climate-friendly aviation, which is currently responsible for many millions of tons of  CO₂

An experienced founder and management team with in-depth market knowledge stands behind elfin.aero GmbH

The name “STEMME” is a globally recognized and successful brand (over 300 aircraft sold) behind the elfin.20

Due to the current politically driven decarbonization of aviation and technological developments (batteries), today is a very good time for an investment

EASA certification

All technical tasks in the research phase have been solved. Even for the type approval of the batteries currently in use, which has been viewed with some skepticism, there are now clear guidelines from the EASA aviation authority that we can meet. There are already successful approvals, such as the Antares gliders.

The timetable for EASA and US FAA approval is generally subject to scheduling risks on the part of the authorities. The aim is to receive approval by mid-2026 at the latest. However, we can realize a limited delivery quantity with provisional or experimental approval (requested by US customers).

Batteries

The timing for the future generation of batteries, which will enable an electric flight time of more than the current two hours, is difficult to predict, but does not pose a risk to the start of production, as the first models are primarily intended for "gliders", for whom two hours of motor time is more than sufficient and exceeds anything usual on the market.

Components

The suppliers for the essential components are well-known business partners. The expensive prepreg carbon fabric from the USA used for the airframe can be replaced by alternatives. Risks in development and production could arise from delivery delays. As a measure, a stockpile will be set up.

In recent years there has been a lot of positive reporting in German and international trade journals, and the elfin project has been followed with great interest by the professional world. Thanks to this media attention, we were able to win a number of orders even before the public rollout.

Recently, we have deliberately held back in the media in order to send a signal to potential customers in the professional world with the first flight in 2025 and to trigger an expected flood of inquiries. This reticence was also due to the wait for secure access to the next generation of batteries, which now opens up the possibility of enabling the transition to electric motor flight with electric flight times far beyond the performance of high-performance gliders.

Articles describing the ELFIN project in detail have been published in the following international journals and portals:

Aerokurier (D), Fliegerrevue (D), Wikipedia (INT), flieger.news (CH), Gliding Magazine (CH/DE), segelflug.ch (CH), Aerobuzz (DE/INT), Cockpit.aero (CH), EAA-Sports Aviation (USA), Flyer (UK), Samolotypolskie (PL), Cafe Foundation (USA), Airframer (UK)

elfin.aero GmbH was founded in 2023 by Dr. Reiner Stemme and Dr. Wolfgang Stemme. It has a sister company , RS.aero GmbH, which has started with the development of the technology carrier ELFIN, but will in future focus on the development and marketing of aircraft and systems for commercial aviation and security forces.

Based on an exclusive and globally valid license agreement with RS.aero GmbH, elfin.aero GmbH is responsible for the further development and worldwide marketing of the ELFIN technology platform in private aviation. The ELFIN platform also serves us for innovative further developments that are expected to lead to patent applications as early as 2025.

Due to more than 40 years of experience in aviation, Dr. Reiner Stemme and his team have a high-quality network of international manufacturers and research institutions.

Elfin.aero GmbH has currently rented an 800 m2 production hall at Schönhagen Airport. The construction of its own 4,000 m2 production hall on a leasehold plot at Schönhagen Airport is being planned. Completion is planned for 2027 at the latest.

The company is based at Schönhagen EDAZ airport, one of the busiest GA airports in Germany with a high proportion of business flights. Our airport is about an hour's drive from the center of Berlin.