Breakthrough: Invisible surveillance of airspace

The passive TwInvis radar by Hensoldt in use

Radar devices have been working in the same way for decades: The radar emits electromagnetic waves. Objects such as airplanes reflect these waves as echoes, which in turn are detected by the radar. This allows the position and direction of an aircraft, for example, to be precisely determined. At airports, during major events or at political summits requiring high security, radar technology is the central instrument for controlling traffic and monitoring airspace.

It's possible without radar waves

The passive radar newly developed by Hensoldt under the name TwInvis fundamentally changes the way radar works. Instead of emitting its own signals, it uses the signal echoes of existing third-party transmitters. These can be radio or television transmitters whose waves are also reflected by aircraft. TwInvis detects these reflected signals and locates the aircraft accordingly. In the process, the passive radar processes signal echoes that are billions of times weaker than the original signals. A single TwInvis unit can thus monitor up to 200 aircraft in 3D within a radius of 250 kilometers.

Many possibilities for use

The new passive radar is significantly smaller than previous radar systems and can be easily integrated into an off-road vehicle or a van. Since it does not emit its own signals, it can also be used in urban areas – unlike active radars. And it can also be used more quickly, because there is no need for coordination with the authorities. TwInvis is therefore perfect for monitoring major events such as football matches or critical infrastructures – even at short notice.

Passive radar can also be used at airports to supplement the sensors used in air traffic control, for example as a backup. TwInvis can be used as a new instrument for monitoring the airspace at small and medium-sized airports that are not yet equipped with primary radar. And it also provides support in areas with severe restrictions, such as areas where mountain slopes or other obstacles impede normal radar waves.

However, TwInvis also opens up new possibilities in the military sector. In areas with a low transmitter density, for example, several separately placed devices can work together. Since the lack of its own radar waves makes the radar practically invisible, it can neither be detected nor jammed by the enemy.

World-leading technology made in Germany

The technology underlying TwInvis has been researched worldwide for more than 15 years. Hensoldt has now achieved a breakthrough with TwInvis. A passive radar demonstrator was presented to the public for the first time at the ILA Berlin in April 2018 and shown in operation. The company has invested several million euros of its own funds in its development and carried out studies in cooperation with the Federal Ministry for Economic Affairs and Energy, among others. This innovation is further impressive proof of the global breakthroughs that aviation research in Germany can achieve.

Optical tomography from industrial 3D printers

Heat distribution during the build process (source: EOS)

Even the smallest deviations in components, such as undesirable cavities or pores, can pose a risk to aviation safety in an emergency. Every component must therefore be thoroughly checked. To avoid having to destroy the parts, the inspection is carried out using ultrasound or X-ray methods.

Complete documentation

Components from industrial 3D printers cannot be inspected as thoroughly using these processes. One example is selective laser melting: In the 3D printing process, metal powder is melted and applied in wafer-thin layers until the desired component is finished. MTU Aero Engines has been manufacturing borescope eyepieces for the A320neo geared turbofan engines in this way for more than five years. The part, a few centimeters in size, which is located on the housing of a low-pressure turbine and allows the insertion of a borescope, is made applying more than 1,000 layers. The problem: due to the layered structure produced with selective laser melting, any deviations are usually very small or extremely flat. The geometry of additively manufactured components is sometimes considerably more complex than that of cast or milled components. Conventional inspection techniques such as ultrasound or X-rays are often not sufficient to detect deviations.

The layer-by-layer buildup principle of additive manufacturing processes requires a completely new solution for quality assurance. MTU Aero Engines has developed a new inspection procedure for the particularities of this manufacturing process: The system, called EOSTATE Exposure OT, is distributed by EOS and works on the basis of optical tomography (OT) – an imaging method used in medicine, for example, to examine tissues. During the manufacturing process, a high-resolution camera documents the entire manufacturing process from the first to the last layer – a completely new quality inspection offering maximum efficiency.

Unique control

The inspection during the manufacturing process eliminates the need for subsequent quality controls for volume testing. This reduces time and costs considerably. In addition, the system collects valuable data that can be used for later optimization of components and manufacturing processes.

During development, MTU collaborated with EOS, the world's leading technology provider for industrial 3D printing of metals and polymers. EOS has been distributing the joint development since June, so that OT can also be used by other companies. The development work is also continuing. The aim is to provide a monitoring system that can also be used for sequential control of the welding process. In the final stage, the monitoring system is to be further developed into a fully automated quality assurance and control system to eliminate defects while having it approved as an inspection procedure at the same time.

Radio direction finders ensure safety

The complete technology of the direction finder system DF-ATC-S is integrated in a box on the mast.

Radio direction finders support air traffic control at airports and checkpoints. They detect the direction to a calling aircraft and display it on the radar image. If several direction finders are used, even the position of aircraft can be determined by taking cross bearings. On the radar screen, the calling aircraft is then displayed with a marker. This makes it easy and quick to identify the calling aircraft and avoid confusions and misunderstandings. At small airports without radar, direction finders are often the only source of direction information. Here the bearings are not displayed on the radar screen, but on a supplied panel.

The evolution of direction finder technology

The first radio direction finders were installed at airports in the 1950s. Rohde & Schwarz was there from the outset and is one of the world's leading manufacturers. With the latest R&S DF-ATC-S model, the company has now launched a completely new generation of direction finders on the market. From 2- to 32-channel systems, the new family of direction finders offers suitable configurations and options for every airport and application. This also includes a mast with extensive accessories which facilitates professional installation. Open interfaces provide the bearing data in real time and optionally allow remote control of the system.

Everything in one box

The compactness and outdoor capability of the direction finder is also unique. Digital signal processing and the miniaturization of the components allow the complete system – receiver unit, DF server, air conditioning, GPS receiver and IP switch – to fit in a box on the antenna mast. There is no need to install the system in a building or shelter, as was the case with previous models. The entire system can therefore be installed and be ready for operation in just a few hours and only requires a data and power connection.

The system family offers two different DF antennas. If equipped with the compact antenna, the DF system is easy to carry and therefore well suited for transport. Thanks to its quick installation, the direction finder can also be used at temporary airfields, for example when the Bundeswehr (German Armed Forces) are setting up a landing field for a few months abroad.

Rohde & Schwarz developed the new generation of direction finders completely in-house in just two years – and was able to build on decades of experience. In doing so, the company implemented the system family in accordance with the guidelines of the ICAO and the Federal Supervisory Authority for Air Navigation Services.

Helicopter generation of the future

The Racer by Airbus Helicopters

New design for new records

The new high-speed helicopter is meant to bring passengers to their destination 50 percent faster. The Racer achieves this speed record thanks to a new design. It has one main and two rear-facing side rotors mounted on so-called boxwings. The side rotors allow a fast increase and decrease of the airspeed. This makes the Racer much more agile and maneuverable than conventional helicopters and allow it to fly steeper trajectories. The main rotor rotates more slowly, thus reducing vibrations.

This design alone will allow the Racer to fly much more quietly. Above all, it is the shape of the rotor blades and the skillful combination of the various rotors that are supposed to make this possible. Furthermore, other than classic helicopters, the interaction of the wingbox and the main and side rotors also allow the Racer use trajectories that significantly reduce the noise perceived on the ground. Due to its steeper approach path, it is heard much later from the ground.

The Safran engine also ensures significantly lower fuel consumption. Compared to conventional helicopters, the Racer will fly around 100 km/h faster with 30 percent lower fuel consumption. Overall, the costs per passenger and kilometer are 20 percent lower compared to current models.

European research at its peak

A total of 37 partners in twelve European countries are involved in the project. The airframe is assembled at Airbus Helicopters in Donauwörth while the final assembly of all components and the flight tests take place in Marignane, France. The project partners include the German Aerospace Center (DLR) and its French counterpart ONERA. In Europe, several hundred people are working on the Racer project – more than 100 at Airbus Helicopters alone. The aircraft was developed under the umbrella of the European aviation research program Clean Sky 2 – which once again shows what groundbreaking developments European aviation is capable of.

A demonstrator of the Racer was presented at the Paris Air Show in June 2017. The first flight of the demonstrator is planned for 2020.

Bloodhound for drones

Security forces see all identified drones on a screen

There are an estimated 400,000 privately used drones in Germany at this time. They are available on every free market and practically anyone can purchase them; it is difficult to rule out misuse. The possible threat scenarios are manifold: from provocations in public space to the spying out of secret and sensitive information to terrorist acts.

If major events are to be protected, authorities and organizations tasked with security (BOS) are faced with the question: how can flying objects, some of them only a few centimeters in size, be detected in a huge, sometimes unmanageable area before it's too late? And how can they be targeted and immediately rendered harmless in an emergency?


Answers to these questions come from Fürstenfeldbruck in Bavaria. ESG Elektroniksystem- und Logistik-GmbH has developed a modular drone defense system (GUARDION) together with partners from Germany and Europe. Within a radius of 1,000 meters, the system detects unmanned aerial vehicles and the associated controllers – a task similar to the famous search for a needle in a haystack.

Several mechanisms lead to success. First, the drone and remote control are communicating with each other. While the radio signals are not visible, they can still be detected by special sensors. This is how a drone can be clearly matched to a pilot. Second, a radar system detects all moving objects in the area and can automatically identify drones and distinguish them from birds, for example. No drone can move undetected. And third: microphones and cameras determine the movements of the drone even more precisely.

The responsible security forces receive a clear presentation of the collected information on a screen – and thus always know where drones and their pilots are located. In an emergency, they can initiate organizational security measures or, for example, cut the radio link between the flying object and the remote control – which makes the drone land automatically or fly back to its launch point.

Modular drone defense system GUARDION (Foto: ESG Elektroniksystem- und Logistik-GmbH)


"The requirements for the protection of major events are extremely complex," says Christian Jaeger of ESG. "Our modular drone defense system offers the necessary technologies and can be adapted to the specific needs of our customers." This allows the system to protect buildings and conference hotels just as efficiently and effectively as outdoor areas or entire stadiums. The effect is as big as the system is small: the technology fits into a minibus and can therefore be quickly moved to another location at short notice.

Christian Jaeger adds: "When the American president visits Germany or tens of thousands of soccer fans are celebrating in the fan zone, these major events are accompanied by complex security measures. Drone-defense is an integral part of this and must work reliably when interacting with other technologies. Our system ensures this and can be easily integrated into existing security concepts." Among other occasions, GUARDION, the modular drone defense system of ESG and its partners, was used by the Federal Criminal Police Office at the G7 summit in Elmau 2015, during the visit of US president Barack Obama at the Hanover Fair 2016 as well as at the G20 summit 2017 or the ILA Berlin 2018.


Next leap towards lighter aircraft

Premium AEROTEC presents the world's first CFRP pressure bulkhead demonstrator

We are talking about the so-called pressure bulkhead. In an aircraft, this circular disk provides an airtight seal that seals off the passenger area from the tail. Only then can the correct air pressure be generated on board.

First demonstrator worldwide
Premium AEROTEC now takes thermoplastic CFRP a step further. In just four months, teams in Bremen and Augsburg have developed the world's first pressure bulkhead demonstrator fully fabricated from thermoplastic for the A320. The full scale demonstrator was unveiled to the public for the first time at the ILA Berlin in April 2018. The demonstrator consists of eight equally sized segments – their shape being reminiscent of pieces of a pie. The segments are joined together using state-of-the-art welding technology.

In partnership for less weight
Several partners were involved in the development and production of the demonstrator. Premium AEROTEC was responsible for development work and design. The individual segments were manufactured at the Institute for Composite Materials (IVW) in Kaiserslautern, and the welding was done in close cooperation with the DLR Center for Lightweight Production Technology in Augsburg.

With the demonstrator, Premium AEROTEC shows that it is possible to produce even large components with lightweight thermoplastic CFRP materials. The potential is enormous: the innovative lightweight version of the A320 pressure bulkhead enables a reduction in weight of around 25 percent compared to today's standard design – without reducing the strength of the component.

In the coming months, the company will gather further insights into what is technologically sensible and economically efficient in designing such large components made of thermoplastic CFRP and drive forward the necessary production processes.

Cybercrime: Security for satellites

Caption: © Thales / BlackSky Next-Generation Satellites

To ensure that a satellite can fulfill its mission, it is usually equipped with several computers and corresponding software. For example, an application operates sensors in order to input and process weather data. Another controls robot arms, and still another navigates the satellite through space.

Like any other software, such applications can potentially be vulnerable to security gaps that are exploited by malicious hackers (crackers) to take over the satellite. This danger is still relatively new: until about 20 years ago, the number of satellites was low and the possibilities for external takeovers were limited. Security was a marginal issue. Today, satellites without protection against such attacks are no longer conceivable, because the knowledge and technologies needed to carry out these takeovers are easily available on the market. One consequence is that such attacks may increasingly become a part of modern warfare due to their devastating effects.

The possible dangers are manifold. Unauthorized persons could hack into the communication software, manipulate it and thus force a failure. Nevertheless, they could also take control of the navigation and cause the orbital body to crash. The increasing networking of several satellites or even swarms of satellites are also of particular importance. One must therefore prevent unauthorized persons from gaining access to a satellite and manipulating the entire swarm. It is also vital to protect the data processed on satellites.

The satellite operating system

This is where SYSGO AG comes in. The company has been developing an operating system for security-critical applications since 1999: PikeOS. One could simply think of it as a "normal" operating system like Linux but specially developed for the extremely high requirements in space, for example with regard to security and certification. Even before the first line of code was created, PikeOS was designed to meet the exceptional requirements of the aerospace industry. Moreover, as part of the OBC-SA project, PikeOS will be made operational on the computer system of the same name, which is being developed in a collaboration between Airbus and Fraunhofer FOKUS.

The core idea: all applications of the satellite run on one computer, but are strictly separated from each other. Apart from protecting the various applications themselves, this also prevents third parties from hacking into the weather-observation software, for example, and from there, without much effort, getting into the navigation software of the satellite and causing it to crash. Especially in times of increasing networking, this is a major issue. In order to achieve a similar degree of protection, until now the applications have had to run on several physically separate computers. Since the SYSGO project requires only one computer, it saves costs and weight in addition to the gains in security.

Off-the-shelf software

The aim of the project is to have a computer including software that users can buy "off the shelf" and then assemble and use for a variety of purposes. The security solution is also suitable for manned space travel and even for use on the ISS, where significantly higher security requirements apply than for a satellite.

OBC-SA is a joint project with partners Airbus and the Fraunhofer Institute for Open Communication Systems. These partners develop the hardware—i.e., the actual computer—which has to be particularly resistant to radiation, for example, due to its use in space. The systems are currently being integrated, and environmental tests are planned for the remainder of the year. The project will run until the end of 2018.

A different kind of hybrid

Conventional manufacturing methods can be optimally combined with additive manufacturing processes (Foto: PFW Aerospace)

Expectations for 3D printing are high: some components can be manufactured faster and much more individually, while some of the processes allow for new geometric shapes and promise weight reductions. However: not every component in an aircraft is geometrically complex and benefits from the laborious and expensive additive manufacturing processes – just think of pipes, sheets or panels. These parts can be produced more efficiently and cost-effectively by conventional means.

The best of both worlds

PFW Aerospace wants to combine both worlds. In a current project, the company is investigating how complex functional components such as suspension elements can be directly attached to a simple product, for example a welded intermediate product, by means of laser deposition welding. In laser deposition welding, powder or wire is melted as a filler material through a nozzle using a laser. The goal is a process combination of cost-effective, conventional manufacturing technology and additive manufacturing that combines the advantages of both processes and leads to a high-quality and economical component. This makes it possible to do without all component-specific fixtures and tools that are necessary for welding, for example – a digital machine program is sufficient for additive production.

The hybrid manufacturing approach is particularly interesting for materials such as titanium alloys. Depending on the alloy, these are difficult or even impossible to form at room temperature and require more machining effort than aluminum, for example. This makes the processing complex and costly. Additive manufacturing processes offer an alternative here.

Research funding makes it possible

The project is funded until 2020 by the Aviation Research Program of the Federal Ministry for Economic Affairs and Energy. Depending on the research results, the first components produced with this process could be used as early as 2021.

Lightweight pipes for the aviation industry

Pipes made of high-performance thermoplastics by PFW Aerospace

The demands on pipes in airplanes are high: the space is tight, some of the pipes are bent over 180 degrees. The temperatures fluctuate between minus 65 °C and plus 250 °C. In hydraulic applications, they must also be able to withstand extreme pressures of over 17,400 psi. So far, it has been possible to withstand these stresses almost exclusively with some heavy metallic materials such as steel, aluminum and titanium.

Lightweight construction of piping systems

PFW Aerospace is no longer satisfied with this situation. In a research project lasting several years, the company, together with partners, has developed new processing methods for extremely resilient plastic pipes to be able to replace metallic pipes in many places. So-called high-performance thermoplastics are used here. These materials are not only significantly more heat-resistant than previous plastics, but are also resistant to aggressive liquids such as kerosene or hydraulic fluid.

But most importantly, the plastic pipes are up to 40% lighter than metallic pipes. An enormous savings potential that also benefits the environment, because every gram of weight saves fuel and reduces CO2 emissions – another example that ecological and economic goals in the aviation industry are congruent.

Joint investment

The new processing methods for high-performance thermoplastics were developed as part of a project funded by the Federal Aviation Research Program. In addition to PFW, other industry partners and research institutions of the TU Kaiserslautern were also involved. PFW has since invested a seven-figure sum in new production facilities.

The first lightweight pipes have been in use in the A350 since 2014. There they remove liquids from the cargo hold – for example when snow melts on the cargo. But this is only the beginning. PFW is currently working to ensure that fresh and waste water pipes made of high-performance thermoplastics will soon go into series production. In the long term, these plastics will be able to replace almost all pipes in aircraft with additional modifications.

3D navigation

The new Surround View 3D assistance system (Photo: AKKA)

As in vehicles, the so-called Surround View 3D enables a three-dimensional all-round view of the aircraft to be generated from any angle in real time. The system's computer graphics algorithm uses images from the externally-mounted cameras to create a three-dimensional image of the aircraft environment. Using a 3D mouse or touch control, the pilot can adjust the perspective dynamically and continuously.

More security and more entertainment

The system in this way supports safety when navigating on the ground and during take-off and landing. In addition, the 3D images can be transferred to the entertainment screens in the cabin, creating an exciting experience for passengers who can follow the aircraft in real time and in 3D while maneuvering.

Transferring the concept from the automotive sector to the aviation world was a major challenge: The developers at AKKA had to rethink all processes and components – from graphic algorithms, hardware porting and camera calibration through to the operating concept. They also had to meet new requirements in terms of high data volumes and real-time data processing.

The new Surround View 3D assistance system was presented to the public for the first time at the Interior Expo in Hamburg in April 2018.

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