Development of Technology Demonstrators

A Note To The Reader

This section describes how Saab invested in technology research both of its own accord and in partnership with various companies, research institutes and academia in Sweden and internationally.

In order to advance aerospace research in an effective manner, initiatives were taken to, among other things, implement various programmes aimed at developing technology demonstrators.

These initiatives were implemented both of Saab's own accord and through participation in a variety of research programmes in Sweden and abroad, and this has strengthened competence development.

The Gripen Demo technology demonstrator was a flying test platform for the next generation of Gripen and for the further development of existing versions. The Neuron project brought knowledge on unmanned aerial combat vehicles and provided extensive experience of employing new ways of working within Model Based Definition (MBD). The work with SHARC formed the foundation for successful autonomous take-off and landing. The MIDCAS programme demonstrated how unmanned aircraft would safely be able to fly in the same airspace as piloted aircraft.

Background

Technology demonstrators are invaluable when showing new potential capabilities to politicians, customers and government agencies. An example of such a technology demonstrator is Gripen Demo which very successfully demonstrated Saab's ability to develop a modern fighter aircraft to deter future military threats.

Another important reason for using technology demonstrators is that work can be conducted with different types of product concepts, which define and show the most important properties for the products to be developed. Technology demonstrators are a good way to develop expertise and strategic partnerships, and to be able to conduct practical tests of new product concepts together with different customers.

It has also been necessary to continually provide the development organisation with new, challenging projects in order to retain skills. This also allowed for the retention of a high level of expertise in advance of major development orders.

Recommended reading

The author recommends the following texts that relate to this story: In chapter Having a low life cycle cost under the heading Systems Engineering in chapter Keeping unique development skills under the heading Technical capability development of control systems and in chapter Ensuring long-term operations capabilities under the heading Capability Development in an International Environment.

This section concerns the marked areas in A Journey of Change in the Aircraft Industry

Summary

Since the beginning of the 2000s, Saab has invested heavily in international expansion. This should be viewed against the backdrop of changes in Swedish defence policy. At this time, there was no indication that the Swedish state intended to invest in major defence orders or development assignments. These new conditions entailed significant opportunities as well as challenges, as the defence materiel market had traditionally been a national interest. However, the leap from national interest to export business for defence materiel required major investment.

Saab therefore invested heavily in business deals at a high system level in the civil and military markets alike. In order to continuously work in this manner, well-established technological research has existed within Saab for quite some time.

The work involved with product management has been important for Saab. When selecting the right areas for future R&D investments, it is necessary to possess a clear understanding of one's own capabilities, market demand, prospective technological development and one's own future product portfolio.

To effectuate R&D initiatives a "Technology Roadmap" must consistently be utilised for Saab's entire product portfolio.

One of the most important strategies for Saab's "Technology Roadmap" over the last 15 years has been to develop technology demonstrators and key technologies. This has been realised through participation in the Neuron Project and through the development of the Gripen Demo technology demonstrator.

The Gripen Demo technology demonstrator was a flying test platform for the next generation of Gripen and for the further development of existing versions. Gripen Demo was developed with new features such as a new engine with increased thrust, an AESA radar, increased range, new landing gear, expanded weapons capacity and improved aircraft electronics structures.

The purpose of developing Gripen Demo was to be able to contribute to increased export sales and to demonstrate Saab's long-term commitment to the Gripen programme. The demonstrator programme would provide experience and consequently risk reduction, shorter development times and lower costs in subsequent development programmes.

Description of content

  • One of the most important strategies for Saab's "Technology Roadmap" over the last 15 years was to develop technology demonstrators and key technologies.
  • Through investing in the development of proprietary technology demonstrators and through participation in various research programmes, Saab was able to strengthen its competence development.
  • The Gripen Demo technology demonstrator was a flying test platform for the next generation of Gripen and for the further development of existing versions.
  • Requirements pertaining to unmanned aircraft can be considerably more varied than for piloted aircraft.
  • To successfully accomplish completely autonomous flights without a pilot has been an important step in Saab's development of autonomous UAVs.
  • Flights with SHARC demonstrated the possibilities offered by autonomous flight.

Technological Research

Since the beginning of the 2000s, Saab has invested heavily in international expansion owing to changed conditions for defence orders as a result of Swedish defence policy. This entailed significant opportunities as well as challenges, as the defence materiel market had traditionally been a national interest. However, the leap from national interest to export business for defence materiel requires major investment.

Work is thus necessary with a number of key technologies; such that are critical or include new technology that provides important product characteristics.

Within these key technologies it is possible to identify aircraft-specific basic technologies as an essential foundation.

Aircraft-specific basic technology is often developed within research institutes and universities. In addition to this, more "generic technology" and industrial technology is also needed, i.e. basic technology that has applications in society, such as in computers and communications systems.

“Technology roadmap”

The work involved with product management has been important for Saab. When selecting the right areas for future R&D investments, it is necessary to possess a clear understanding of one's own capabilities, market demand, prospective technological development and potentially one's own future product portfolio.

To effectuate R&D initiatives a "Technology Roadmap" must consistently be utilised for Saab's entire product portfolio. An array of assessments are conducted in a Technology Roadmap. Examples of such assessments include:

  • Market trends.
  • Product properties.
  • Direction of defence capabilities.
  • Operational capacity and capability in different forms of conflict.
  • Industrial collaboration within Sweden along with international industrial collaboration.
  • Economic prerequisites for future technological development based on domestic and international development programmes.
  • Future industry cooperation and different ways to industrialise products moving forward.
  • Possibility to develop new, or improve existing, product concepts.
  • Different factors affecting competitiveness such as competitor analyses.
  • Future development within various technology areas.
  • The capabilities that must be developed for each technology area.
  • Technological trends in general concerning Saab's products.
  • The impact of technical and technological development on Saab's product portfolio.
  • How synergies can be utilised in development within the product portfolio.
  • The capabilities that can be developed in Saab's products over time from a 5, 10 and 20 year perspective.

Technology areas judged as of particular importance for a proprietary product portfolio would need to be substantiated and oriented based on "Technology Roadmap" assessments. The most essential aspects of technological and product development from a 5-10 year perspective must be analysed. The results establish guidelines for practical projects for long-term business, product and operational development.

One of the most important strategies within Saab's "Technology Roadmap" over the last 15 years was to develop technology demonstrators and key technologies. This has been realised by participating in the Neuron Project and by furthering the Gripen Demo technology demonstrator.

The Neuron project has brought knowledge on unmanned fighter aircraft and has provided extensive experience on employing new working procedures within MBD. The Avionics Demo project in Gripen Demo proved the most ground-breaking for future system architecture. Major work involving systems integration has been carried out effectively within the project.

Both projects jointly provided the justification needed for the creation of a comprehensive capability for future development projects. The comprehensive capability concerns product, technological, market and operational capabilities. An interesting outcome of these technology demonstrators was to see how the number of requirements and amount of research regarding technological solutions can impact the risk outcome during the design of technological solutions.

The long-term participation efforts in various research projects has been incredibly important; participation in NFFP is an example of this. Particular market perspectives are interesting to follow. It is also imperative to possess good control over which technology areas will be developed and which will be important for the development of new capabilities in future projects. Research projects also afford opportunities to ascertain which prospective partnerships can prove rewarding if developed further.

It is crucial to carry out research projects on different TRL levels, regardless of whether these projects are run totally of own accord or in concert with other companies, research institutes or academia.

Important research areas pertaining to the aerospace industry exist within autonomy, avionics, integration, signatures, survival, decision support, computer science development, communications, HMI, etc.

It is of primary importance to understand how maturity can be achieved for different systems according to the "TRL scale" when undertaking new system and product development projects.

Which studies exist at low TRL levels? Which technology demonstrators exist at levels 5-6? Which system development projects are at TRL levels 7-8?

Interesting questions to consider during research planning include:

  • Assessments of the technology available at a given time.
  • Is there anything indicating that a possible technological leap is under way?
  • Can major performance increases be expected with a certain new technology?
  • What form will cost development take in the future?

One of the most factors for well-functioning research work is to define the research programmes in a roadmap that provide longevity and sustainability. A good example of this is to constantly implement different types of technology demonstrators which can then gradually develop different capabilities. Working on a wide front and taking part in numerous international projects is valuable, motivating and generates interest.

Technical planning has evolved into an excellent working procedure. It absorbs technological trends and competency requirements and is linked to needs and changes in working procedures. It applies to methodology, changing needs and development environments for systems development and IT. Furthermore, technical planning serves as a foundation for various research studies into future techniques and technologies.

There is a clear reason to interconnect technical planning and product planning more intimately, as technological development in certain areas is very robust and many new technological solutions can be transferred to products more rapidly. An example of this is 3D printers which offer possibilities for entirely new lightweight designs within the aerospace industry.

Cooperation within Technology Research

To make this possible, an array of research programmes were constantly carried out, either of own accord or in partnership with other industries and research institutes like the Swedish Defence Research Agency (FOI), which is one of Europe's leading research institutes within defence and security.

A national aeronautics research programme, NFFP, has existed since 1994. The aim of the programme is to further develop research capabilities in Sweden within industry, research institutes, universities and colleges. The utilisation of this will also be coordinated. As a part of aeronautical research in the country, the NFFP will also contribute to strengthening the competitiveness of Swedish industry.

The programme has seen several doctoral and licentiate degrees within important areas in industry over the years. Numerous scientific papers have been adopted by and published in renowned scientific journals and have roused international attention.

The NFFP programme has carved out a strong position for Sweden in Europe, where national Swedish collaboration is seen as a shining example of cooperation between the research sector and industry. This cooperation has made it easy for Swedish educational institutions to access the European research projects in which Swedish industry participates.

An excellent case in point regarding collaboration between industry and research is NRA Flyg 2010, which is an example of an aerospace research agenda and a unique collaborative project between parties within Swedish aerospace research and participants from companies, institutes and academia.

Participants in the programme were VINNOVA, FMV, FM, FOI, Saab, Volvo Aero, LiU, KTH, Chalmers, LTU, SAI and Teknikföretagen (the Association of Swedish Engineering Industries). This programme covered strategic questions in the following areas: Structures for aerospace strategy, research programmes, funding questions and aeronautical expertise.

In order to practically effectuate the research, various types of technology demonstrators must be developed and produced. Technology demonstrators are an important component in the testing of new techniques and new technologies, but also for testing future and progressive working procedures. The technology demonstrators implemented over the last 15 years have also made it possible to develop effective working procedures.

Several technology demonstrators have been developed in partnership with research institutes, universities, colleges, FMV and the Swedish Armed Forces. Moreover, many initiatives have been undertaken together with international partners within industry as well as with research institutes and universities.

Research through NFFP has played a very important role. And partnerships with academia are of particular importance. Examples of important and productive research programmes include ETAP, NRA 2010, NRIA 2013 and FMV's aerospace research programme. These types of programme were carried out between 2000 and 2009, 2010 and 2012, and 2014 and 2016.

Examples of interesting questions to consider include:

  • The future apportionment between piloted and unmanned aircraft.
  • The form conflicts will take in the future.
  • Decisive factors for air combat forces.

When participating in international research partnerships, it is necessary to define the roles one is prepared to assume in order to influence the formulation of a research package. To benefit from the results produced in the entire research package requires one to serve in a managerial and coordinating role in such a programme.

Technology Demonstrators

A technology demonstrator is a prototype allowing for the demonstration - with various limitations - of a potential technological or operational capability. A technology demonstrator is often created to test new boundaries in technical solutions and to forge a position as a prospective supplier and partner.

Other motives include recognising market and customer reactions to technical solutions for operational needs. For Saab, technology demonstrators are invaluable for developing technical capabilities and for developing new operational capabilities for more streamlined and rational working procedures.

Developing functional demonstrators also serves to successively reduce risks in a project. Technological capability is measured in part by the ability to cover technical solution requirements and in part by the technology's practicability.

Adapting to the altered circumstances resulting from the Swedish state's actions as regards its emphasis on operational defence has brought a number of areas into focus for Saab. Strategic choices have been made such as increased and altered cooperation with partners, investments in technical and technology development, operational streamlining, and investments in various technology demonstrator programmes.

Technology demonstrators are a good way to develop expertise and strategic partnerships and to be able to implement practical tests of new product concepts in order to gain greater understanding of the needs of the Swedish Armed Forces and the most important international customers.

 

Through initiatives to develop proprietary technology demonstrators and by participating in various research programmes, Saab was able to strengthen its competence development. The recruitment of personnel from other sectors has also provided new perspectives which have contributed to increased capability development. The fact that Saab has expanded its participation in international technical studies and research programmes over the last 15 years has also contributed to capability development.

The work with technology demonstrators is a way to "mature" technologies judged as practicable in future products. By investing in model-based development, Saab has also established a partnership with academia to study new aircraft concepts, e.g. the study of aerodynamics, autonomy, etc.

Participation in the international technology demonstrator Neuron strengthened the ability to develop expertise with regard to aircraft design. MIDCAS is another technology demonstrator that demonstrated the potential to effectuate a system able to automatically detect and avoid other aircraft in a similar manner to that of piloted aircraft.

The most important success factor that contributed to working procedure changes has been the implementation of technology demonstrators, which in turn have contributed to new innovations and new working procedures, which have enabled significant skills to be transferred to forthcoming product development projects.

The most important success factor that contributed to working procedure changes has been the implementation of technology demonstrators, which in turn have contributed to new innovations and new working procedures, which have enabled significant skills to be transferred to forthcoming product development projects.

Strategic decisions regarding technology demonstrators

In order to test new technology and new products with new properties, Saab has taken strategic decisions, as mentioned before, to begin developing technology demonstrators. A desire exists to continuously develop new technologies and new aircraft with capabilities that can be utilised in technology development and skills development, and to demonstrate Saab's capabilities to the market. The decision to develop technology demonstrators was a very progressive one, as it allowed existing and prospective customers to see the company's innovative abilities.

Technology demonstrator initiatives were initially viewed from a technical perspective. The orientation of technology demonstrators later also came to include market demonstrators and the development of operational capabilities, i.e. to create effective development environments and tools for the development of technologies and products.

Technology demonstrators are invaluable when showing new potential capabilities to politicians, customers and government agencies. An example of such a technology demonstrator is Gripen Demo which very successfully demonstrated Saab's ability to develop a modern fighter aircraft to deter future military threats.

Another important reason for using technology demonstrators is that work can be conducted with different types of product concepts, which define and show the most important properties for the products to be developed. Technology demonstrators are a valuable way of developing expertise and fostering strategic partnerships. Practical tests can be conducted for new product concepts in concert with different customers.

It has also been necessary to continually provide the development organisation with new, challenging projects in order to retain skills in anticipation of major development orders.

Saab has therefore pursued a focused initiative in a number of technology demonstrators. Various advanced capabilities have been developed to test techniques and technology.

In conjunction with the development of certain technology demonstrators, the streamlining of development processes was also facilitated.

This has resulted in the advancement and improvement of development methodologies and development environments. Furthermore, the methods and different frameworks used to efficiently govern complex processes have also been improved, such as the development of advanced software products and open source codes.

Funding has taken myriad forms depending on the stakeholders involved. Some funding has been provided of own accord while major funding has entailed collaboration with other industries in Sweden and internationally. Substantial funding has come from FMV.

Strategies to develop business and markets have changed over time. By the end of the 1990s, interest had started being directed towards unmanned aircraft, as this was a new market area for Saab. This meant that knowledge needed to be amassed in this area, which was realised by implementing a number of technology demonstrators.

Examples of technology demonstrators

This section briefly describes the purposes of the various technology demonstrators and the impact these had on capability development.

Gripen Demo demonstrated new capabilities in the Gripen system such as increased range and operational capabilities. In addition, advanced technological and capability development occurred in the work on this technology demonstrator. Experiences from development of the Gripen Demo technology demonstrator would also come to be used as input for developing future working procedures, development environments and IT tools.

Examples of technology areas given a great deal of focus include sensor technology, presentation systems for pilots, navigation, autonomous control, simulation and modelling. New working procedures have been used in the form of model-based systems development, as well as model-based development within design and production.

The Neuron programme demonstrated a number of technologies for a UCAV system (Unmanned Combat Aerial Vehicle) and was designed as a combat aircraft. Neuron also constituted the development of an unmanned aircraft with a low radar signature. Neuron was developed for unmanned, autonomous flight. Among other things, advanced avionics (flight electronics) were developed in Neuron. Also demonstrated was a tactical and, not least, effective way to accomplish weapon intervention against ground targets in a modern command and decision support environment.

The programme has provided important skills within aeronautical and systems technologies. But, above all else, the work in Neuron further strengthened Saab's competitiveness with respect to high-tech and cost-effective development and production methodologies.

The work in Neuron has allowed Saab to develop the ability to utilise model-based development, which is now used consummately in all product projects.

Neuron was a joint venture with France, Sweden, Italy, Spain, Greece and Switzerland. The participating aviation industries consisted of Dassault (who led the programme), Saab, Alenia, EADS-CASA, HAI, RUAG and Thales.

The FILUR programme aimed to develop expertise in low radar signature/stealth technology. The technology demonstrator also intended to demonstrate the tactical need for stealth technology in aircraft applications. Implementation of the FILUR programme also served to lay the groundwork for stealth technology requirements in future aviation systems and airborne surveillance systems. Another objective was for Saab and Sweden to advance in the field. It would also afford more opportunities for cooperation with other European nations and defence industries.

The SHARC programme aimed to show that Saab could rapidly and cost-effectively demonstrate autonomous flight. It was hoped that components could be tested in network-based defence. Furthermore, experience in the development of technology demonstrators and work involving airworthiness was also anticipated in order to obtain a Flight Testing Permit (FUT) from the relevant authority. The SHARC is described in more detail later on in this document.

It took approximately a year and half from the commencement of the project until the maiden flight was made. This has proven that Saab is able to develop a flying demonstrator with considerable technological content in a very short time.

The MIDCAS programme (Mid Air Collision Avoidance System) demonstrated how unmanned aircraft would safely be able to fly in the same airspace as piloted aircraft. Systems were tested in order to prevent collisions between aircraft. The MIDCAS programme is described in more detail later on in this document.

Gripen Demo

The Gripen Demo technology demonstrator was a flying test platform for the next generation of Gripen and for the further development of existing versions. Gripen Demo had been developed with new features such as a new engine with increased thrust, an AESA radar, increased range, new landing gear, expanded weapons capacity and improved aircraft electronics structures.

The purpose of developing Gripen Demo was to contribute to increased export sales and to demonstrate long-term commitment in Saab and for the Gripen programme. The demonstrator programme would provide experience which contributed to risk reduction, shorter development times and lower costs in subsequent development programmes. One criterion was to safeguard expertise and resources for the maintenance of Gripen and for further development within various technology areas.

Another important criterion for Gripen Demo was to be able to demonstrate critical improvements with regard to operational characteristics. Gripen Demo demonstrated how to increase performance and flight characteristics, including take-off and landing. Also demonstrated was how to expand the range of Gripen by substantially increasing the amount of internal fuel, and the potential to carry two fuselage pylons for the supersonic condensation of fuel tanks. The new and more powerful engine installed in Gripen Demo enabled it to carry heavier loads.

 Gripen DEMO

Coordinated Demonstrator Programme

Gripen Demo constituted a coordinated demonstrator programme with several smaller sub-demonstrators. The various sub-programmes comprised realisation in virtual simulators, in functioning ground demonstrations and in the air.

The project was instrumental in streamlining improvements development considerably for the Gripen system. The demonstrator programme was an important part of the long-term development plan for Gripen.

The different aspects of the demonstrator programme were as follows:

  1. Demonstrate the increased range for JAS 39 Gripen.
  2. Demonstrate the upgraded structure of avionics systems.
  3. Demonstrate a new radar in the form of an AESA (Active Electronically Scanned Array).
  4. Demonstrate a system with sensors for increased self-protection, including sensors for signal tracking, the detection, positioning, classification and identification of targets and threats, and countermeasures for protecting the aircraft.
  5. Demonstrate Gripen Demo to customers so they could see the development capabilities possessed by the Gripen system.

The Gripen demonstrator programme was effectuated in collaboration with several of the world's leading companies in the aviation industry such as General Electric, Thales, Rockwell Collins, Honeywell, APPH, Terma, Martin-Baker and Meggitt.

Avionics systems

New avionics were also developed. An upgraded avionics system structure includes a completely new computer system for the Gripen, which is integrated with one of the existing system simulators. The intention was to transfer a complete Gripen system into a new system structure with new computers and to demonstrate the intended functionality in the simulator. It was proven that a significant increase of computing power and data-bus capacity was possible, thereby enabling functional further development of the Gripen system. International cooperation, the applicability to UAVs and civil utilisation were taken in to account.

The project also demonstrated the possibility of considerably more efficient development through modularity, software critical structures and more natural "physical" interfaces. In addition, criteria were also devised to deal with problems relating to component obsolescence, etc.

Described below are examples of functions worked in in Gripen Demo's sub-project AvionikDemo.

Surveillance function

The current surveillance function, SPK39, was developed. This was partly accomplished by modelling the function in the Simulink/Stateflow development tool. In order to test the function, a simple model of the surveillance function capsule was built. This model was developed by means of modelling in the Simulink and Rhapsody development tools.

The system functions were then partitioned. The control function and the capsule were each allotted their own partition. Pilot interaction was relocated to one of the partitions. Function testing was carried out via simulations in Simulink.

Test coverage was analysed during module testing, as this allowed for the generation of documents as well as a graphical view of the model. The code that was generated could be integrated into the surveillance function and can be run directly in thin clients or in a demo rig.

Model-based systems development for Emergency Flight Data Display

It was also intended to evaluate methods and tools for model-based systems development, MBSE, in the Avionics Demonstrator An example of this was to develop a new Emergency Flight Data Display Because the Emergency Flight Data Display was a well-known and relatively complete function consisting of sensor data readings, data monitoring, calculations and data display, it was a suitable candidate for the project's purpose.

Gripen possesses an Emergency Flight Data Display which is activated when the system computer, display computer PP-12 or the bus traffic between them stops working for any reason.

The purpose of the Emergency Flight Data Display is to provide the pilot with rudimentary information regarding altitude, speed, course and engine status in order to "get home" and land the aircraft. The Emergency Flight Data Display is implemented as a redundancy directly in the cockpit indicators.

The tools used in the project to develop the Emergency Flight Data Display function were Rhapsody, Simulink and VAPS. Functions were modelled in Rhapsody via UML (Unified Modelling Language), which describes the overall system design and the interface between the system components.

Interface descriptions (header files in C) were generated from this model which were utilised in Simulink and VAPS to provide the function with consistent interfaces. Numerous models were created in Simulink for sensor data unpacking, data quality control, and data display calculations for altitude, speed, course, engine temperature, etc. Graphical elements constituting the pilot interface were modelled in the VAPS tool. The tool generated C codes which were integrated into a PC application for desktop simulations on a regular PC, as well as an application for the targeting system which is a real display from the Rockwell Collins Company.

Unmanned Aircraft

In the last half of the 1990s, after the testing and introduction of autonomous flight in the aircraft JA37 (Automatic Sight) and in Gripen, Saab began studying unmanned aircraft.

Considerable investments in technical studies have been made on a continual basis in various research programmes. Many of these studies have been combined within the framework for different technology demonstrators in the field of unmanned aerial vehicles (UAVs).

The requirements for unmanned aircraft can be considerably more varied than those for piloted aircraft. In piloted aircraft, the pilot and ancillary equipment places a limit on the minimum size.

The sizes of unmanned aircraft can vary from something that can be used in the surrounding area, e.g. to see over the next hill or around the next corner, to something equal in size to a piloted aircraft. The system safety requirements for small aircraft can be somewhat moderate as the aircraft has a limited range and cannot cause any significant damage if it fails in the wrong area.

The requirements for larger unmanned aircraft can be similar to those for piloted one-seater aircraft in order to operate outside of designated airspace or over land.

However, the systems normally monitored by a pilot become critical in an unmanned aircraft, e.g. navigation, attitude and communication. Furthermore, monitoring of the airspace in front of the aircraft by the pilot (to reduce the risk of collision), must be substituted when flying in airspace with other air traffic.

Depending on the mission, an unmanned aircraft must be able to e.g. send information from the aircraft's sensors for assessment. This can apply to aircraft with small operating radii from control stations, but it can also apply to greater distances involving reconnaissance where information is required directly from the aircraft.

Requirements for operating radii and operating times affect the aircraft's capabilities, which in turn affect the aircraft's size and communications solutions. Establishing a direct link with the control station can be a simple solution over shorter distances. But over greater distances, satellite communication or the use of relay stations is required to obtain sensor data with sufficient bandwidth.

The types of sensors to be used have an impact on the size as well as the structural design, so to do the avionics systems used to process and forward data for analysis.

The environmental requirements for equipment are affected both by where the aircraft will operate as regards temperature, humidity, etc. and how the aircraft will fly as regards speed, altitude, etc.

Numerous comprehensive studies of unmanned aircraft have been carried out in which a number of fundamental questions were posed. A few examples of these questions include:

  • Which missions are suitable for unmanned aircraft?
  • Which requirements are relevant for the qualification of an unmanned aircraft?
  • Regulations exist for piloted aircraft, how can these regulations be adapted to unmanned aircraft?
  • How will the internal system architecture for control and missions be designed in order to satisfy airworthiness and mission requirements?
  • How will the aircraft be designed from an aerodynamic standpoint?

Using existing aircraft as unmanned aircraft

Numerous studies have been carried out to develop well-functioning unmanned aircraft.

These studies covered both the theoretical and more applied aspects. This was done in order to more quickly reach the goal of flying an unmanned aircraft. In addition, it was also a way to gain experience prior to future new developments.

Applied studies were conducted both for the aircraft Saab 35 Draken and Saab JA 37 Viggen.

J35 Draken Study

Because the aircraft J35 Draken had a low radar signature and was not used operationally, it could have resulted in an operational UAV. Possibilities were explored to place an avionics system including autopilot in the back seat of a two-seater J35C Draken. Surplus SA10 autopilots from Gripen subseries 1 were used.

The idea was to incorporate all critical computing into this device e.g. navigation. A few modifications were required to the servo steering and for a processor with greater computing capacity. The fundamental part with high systems safety using three channels was to remain unchanged.

An important question during the study was how the automatic commands could be satisfactorily coordinated with a pilot in the front seat.

One proposal was an electrical servo in the back seat connected to the control column so that the pilot could sense the movement similarly to a back-seated pilot. After detailed study of the actual aircraft, it was determined that there was space in the wing for the hydraulic servo as a servo had previously been placed there. By constructing a sufficiently safe aircraft, flight without a pilot could be practicable.

However, a UAV based on J35C was never realised, likely owing to the cost involved.

JA37 Viggen Study

In order to use the aircraft JA37 Viggen as an unmanned aircraft, studies were planned to explore the possibility of autonomous landing based on image processing. Autonomous flight had been developed earlier and had been introduced into production aircraft during the introduction of automatic sighting.

Autonomous landing, however, had never been tested. A tactical optic sensor had been tested in JA37 Viggen and the goal was to utilise the images produced to calculate how approach and landing could be executed independently of help from the ground.

The project proceeded to define the changes to the aircraft and equipment but was cancelled due to insufficient funding.

General avionics systems design in UAVs

According to a study on the safety of unmanned aircraft from 2000, it was decided that similar requirements should apply to system safety in an unmanned aircraft exceeding a certain size to those for piloted aircraft. An unmanned aircraft only poses risks to third parties as there is no pilot on-board.

The same regulations as those used in aircraft weighing less than 6,000 kg have therefore been used for unmanned aircraft. The regulation is known as EASA CS-23 Normal, Utility, Aerobatic and Commuter Aeroplanes.

There are a number of general views on the design of aerial vehicles, not least for unmanned aircraft, where links and safe navigation are additional requirements supplementary to those applicable for piloted aircraft. Described below are several determining factors that must be considered during the development of unmanned Aircraft.

  • System safety
  • Secrecy levels
  • Accessibility
  • Limitations on weight, volume and power consumption
  • The number of units to be manufactured
  • The lifespan of the system
  • Capacity reserves and development potential

System Safety

The requirements can be allayed for demonstrators flying in a designated airspace over a sparsely populated area. Even if the aircraft fails it is unlikely to cause any significant damage.

Handling critical system safety functions in an unmanned aircraft is very reminiscent of the control system in a piloted aircraft handling input signals. There are more critical flight safety functions in an unmanned aircraft than in a piloted aircraft. Attitude angles and navigation become critical if there is no pilot controlling the aircraft. If, for example, the attitude angle in a roll becomes totally askew, the unmanned aircraft will fail immediately, while a pilot is able to detect this directly if some form of external reference or attitude indicator exists. If navigation becomes inaccurate, there are many ways for a pilot to determine position.

The redundancies for critical flight safety information should be of the same magnitude as a control system in an aircraft of the same size in order to satisfy requirements for low failure rates. For the tactical system it is more a question of which probability can be allowed for an aborted mission.

Corresponding requirements for system safety and accessibility must also apply for a control station and for communication with the aircraft. This can be implemented by using e.g. two independent ground stations, with one acting as a reserve.

Secrecy Level

The requirements for a test aircraft that does not contain any classified sensors can be very moderate. The critical part is understandably the command link which prevents anyone from assuming control of the aircraft. The interpretation of telemetry to the ground can be very complex but with trivial content from a secrecy standpoint.

A more classified aircraft should be separated so that a tactical component handling confidential information is separate from the rest of the critical flight safety data. Separation can be achieved by means of a secure firewall between the systems and information encryption when required. Links for controlling the aircraft and transmitting sensor information to the ground are of paramount importance.

Accessibility

Accessibility requirements for a demonstrator can be considerably lower than for operational systems. SHARC was a single system in which several errors could have resulted in the loss of the aircraft. For this reason, two identical aircraft were built. Many problems existed that could lead to aircraft failure, notwithstanding internal system errors. Environment during flight and incidents on the ground.

During the construction of the aircraft, factors such as electrical environment, temperature, humidity and vibrations were taken into account. SHARC consisted of some self-produced devices and purchased equipment for which the electrical environment requirements were not stipulated pursuant to normal rules for aerial equipment. The electrical environment sensitivity was therefore tested by irradiating the entire aircraft with the type of radar to be used for in-flight monitoring and other transmitters, e.g. flight radios and mobile phones placed near the aircraft.

A qualified assessment was carried out for humidity and temperature requirements, which ascertained the lowest temperature requirement (-10 ˚C) for controlling the aircraft without gloves. The requirements for air-cooling over the uncoated computer circuit board were shown to correspond well with the requirements for low humidity in order to observe and control the aircraft.

Limitations on weight, volume and power consumption

It was not possible to utilise regular devices built for flight in a small aircraft such as SHARC. Limiting factors included weight, volume, power consumption, lack of air-cooling and cost. Devices were sought from other applications, e.g. radio communication, where devices designed for buses were utilised. If nothing suitable could be found, they had to be built. This was the case for the computer in the aircraft.

Number of units to be manufactured

If only one or a few aircraft were to be built, ready-for-use approved devices were to be identified. Ready-for-use devices that could be purchased were preferable, in the form of COTS (Commercial off the Shelf) or COTS with minor modifications. If the number of aircraft to be produced increases, an even greater proportion of suitable devices will need to be developed. A good alternative would be to identify devices which could be used without having to be modified. The modification of existing airworthy equipment can become expensive even if the alterations are minor.

Lifespan of the system

The number of years a system can be used and produced is a crucial parameter when designing devices as well as entire aircraft. During the design of aircraft in great numbers over a long time, it is important to select suppliers and components which can be expected to still exist on the market throughout the production period. If it is judged that it may be difficult to acquire components in the future, it may be necessary to purchase components for the entire estimated manufacture volume.

Reserves and development potential

It is imperative to determine the software capacity required in the final aircraft early on, both with regard to memory and computing. Estimates can be improved considerably by executing portions of the final code or other previous and similar code. This is done in a similar computer to the one that will be used. Differences to the final code can then be estimated. Using general estimates based on computing performance does not produce good results.

It is imperative to estimate early on which time delays can be accepted along with the frequency of updates required for the system's various functions.

It is crucial to consider these requirements even when manufacturing a single aircraft. Otherwise the risk becomes too great of having to carry out major software modifications. A reserve must exist for operational aircraft for supplementary future functions. Upgrading memory or computing capacity often becomes complicated when done later.

When producing a larger number of units, the physical development potential must be taken into consideration, e.g. the possibility of adding new functions by introducing new devices.

Development potential is also essential for the development tools used in systems development and for software development. It is important to select suppliers - to the greatest extent possible - who will continue to exist in the market and who are able to further develop tools.

Costs can be reduced through a flexible and scalable system. This can be accomplished by employing general accepted standards for all areas. Particularly important are those for methodology, development and upgrading of systems, communication with and within the aircraft, implementation in software and the utilisation of previously developed software and devices.

Communication

Communication with the control station in an unmanned aircraft is essential from a flight safety standpoint in an entirely different way than for piloted aircraft. For larger aircraft, there must be double command links to the aircraft, designed so that no external party can assume control.

Direct communication with the aircraft can be used when it is nearby. The return requirements for command link bandwidth and status information can be very moderate. Therefore, lower frequencies and omnidirectional antennas can be used. Frequencies around 500 MHz were used in SHARC for commands and telemetry with omnidirectional antennas on the ground as well as in the aircraft.

The transmission of sensor data requires larger bandwidth and therefore higher frequencies in general, which require directional antennas. A directional antenna was used in SHARC connected to a camera which was used to film the flights. Without the antenna, reflections on the ground caused disruptions. Superior systems usually have command link possibilities, this also applies to sensor data links.

Sharc Technology Demonstrator

SHARC was a technology demonstrator that Saab began developing in 2001. The maiden flight took place in February 2002. Several test campaigns were carried out over the years. The earlier tests included autonomous flight both within and outside of visual range. On Wednesday, 25 August 2004, Saab performed the first fully independent SHARC flight.

The work with SHARC laid the groundwork for successful autonomous take-off and a landing. Successfully completing fully autonomous flights - which meant flights without a pilot - was an important step in Saab's development of autonomous UAVs.

There are several advantages to being able to perform autonomous take-off and landing, as these constitute a large proportion of the errors occurring in UAVs. Automating these aspects of the flight results in dramatically reduced risks. Both tactical and operational advantages are attained with the capability to land at twilight or in the dark.

The use of image processing as a landing aid was studied further in conjunction with the final SHARC campaign. Image data processing was performed on the ground during landing but no feedback to the aircraft controls was ever provided. However, this would have been possible by calculating pilot commands on the ground and transmitting this to the aircraft. Image processing was based on video transmitted to the ground from the forward camera.

By performing flights with autonomous take-off and landing, Saab demonstrated it was a company that could be counted on in future international UAV collaborations. The flights took place during a test campaign at the test grounds of the Swedish Armed Forces in Vidsel.

The project comprised building a physical aircraft with the subsystems required to achieve the objective. This included developing configuration-dependent avionics systems including autopilot for autonomous flight with small UAV demonstrators.

Simple electrical servos were used. It was also shown that images could be transmitted to the ground and forwarded to networks with the simplest possible equipment.

Without any assistance from the pilot, SHARC completed a fully autonomous mission prior to landing on its own, by means of differential GPS and a radar altimeter.

Various avionics and control system architectures were also studied during the development of the SHARC technology demonstrator. Experience was utilised from, among other things, the work on JA37 Viggen and Gripen, as well as from a number of UAV studies.

Studies were being done parallel to this on aerodynamic aircraft design optimised for flying at high subsonic speeds. Different designs were studied and wind-tunnel tests were conducted. The aircraft design tested in the wind-tunnel was later utilised as a framework during the design of SHARC.

SHARC was a technology demonstrator designed to fly on only a few occasions in very sparsely populated areas in designated airspace. The requirements for system safety could therefore be significantly reduced in comparison to aircraft flying outside of a designated airspace. The requirements for functional testing could be simplified in the same way. Inspection of the software and the integration thereof was carried out in a rig containing the actual devices.

The requirements for device qualification in the avionics system could also be simplified along with the system's architecture. SHARC could be permitted to fail owing to single errors, which places it apart from e.g. Gripen or similar aircraft. Several errors can occur in advanced aircraft - including in the control system - without making it impossible to continue flying and then landing.

Autopilot in Gripen, for example, has three independent channels to provide satisfactory safety through redundancy.

In unmanned systems, pilots on the ground must have the same prospect of affecting the flight as in piloted aircraft. Even when the aircraft is flying autonomously, the operator must be able to direct changes if something happens, e.g. another aircraft enters the vicinity. This requires a multitude of links.

The figure depicts the different types of communications links existing between the aircraft and the ground station.

The avionics system contains the same basic components found in other aircraft, but in much more simplified designs. There was very limited redundancy in SHARC. The central computer consisted of control systems, primary data, navigation and task management. Input signals were made up of, among other things, air pressure, acceleration, angular velocity, GPS and radar altitude, in addition to commands via links from the ground.

Used in the structuring of the SHARC avionics system were e.g. pressure sensors, radio links and video cameras for ground use, which were judged capable of handling the environmental requirements. Saab constructed a computer and interface for communication with rudder servos and the engine. The limit on temperature range was set to -10˚C, owing to the pilot's potential for fine control, which simplified the electronics. Electronics cooling using the surrounding air occurred directly over the circuit board. The requirements for pilot visibility corresponded to the permitted moisture content of the air-cooling.

A table was used to define the mission, for which each branch was associated with alternative flight paths. In the event of an error occurring, the shortest flight path back to the base would be implemented automatically. Or alternatively, if a failure occurred in a vital component, e.g. if the engine stalled, the aircraft would itself be able to find a suitable landing area. This method has been patented.

Despite the simple system design and the risk of failure due to many single errors, both aircraft used were certified airworthy upon completion of the test flights. A number of unexpected incidents had occurred but nothing serious enough that could not be remedied. The detailed function was determined by parameters that could be changed between flights, which proved adequate. It was easier to introduce and qualify changes in this manner than through a new software version.

The development of software functions was simplified radically by utilising the system development environment for model-based development, which was developed for the Gripen control system.

Avionics and control systems were defined by means of the system development environment, and "high level" models were used. It was also possible to generate code completely automatically.

Auto-generated code was used in the same way for the Gripen control system in simulators and for checking manually coded flight software. Auto-generated code was also used in SHARC during flights, which expedited development considerably.

Testing the system on the ground

The total system must be inspected prior to the maiden flight as part of the process for qualifying the system for flight. This must include inspections of the entire system by checking that all devices functioned simultaneously. An interoperability test must be carried out. Even if all devices are approved from an electrical environment standpoint, tests must be carried out in a complete system. This also means that the various communication equipment must not be permitted to disrupt each other or any other aircraft.

A very effective way to test whether the entire system is functional is to connect the aircraft to a simulator in order to simulate the flight. This takes much longer and costs more, but it is crucial for a new aircraft or after major changes that may affect flight safety. This method has been employed for, among other things, the maiden flight with ESS01 in aircraft 37 -21 Viggen, target sighting tests in aircraft 37.301 Viggen, and was also employed prior to SHARC testing.

It is important to check between flights if any errors have occurred that may affect flight safety, either through automatic or manual tests. Manual inspection is a good alternative for aircraft that are only to be used a handful of times. A comprehensive manual inspection of the interaction between the aircraft and the ground station was carried out prior to each SHARC flight.

Function inspection prior to maiden flight

The developed functions were first tested separately in SHARC, and then later in more complex simulations with e.g. aerodata. By utilising the general real-time simulator developed for Gripen's control systems, the full flight could be simulated at an early stage. Among other things, manoeuvrability tests and manual landing could be performed by utilising the same display used to assess the properties of Gripen's control systems. In order to test the total functionality, tests needed to be performed with the "flight software" in current hardware. Range testing of links were both carried out on the ground and in flights with piloted aircraft.

The complete system was tested via interoperability with ground stations and fully functional aircraft, and during take-off. Furthermore, a full inspection of the system was conducted with the aircraft in the loop by means of a simulator computer calculating signals for e.g. GPS, attitude angles, angular velocity, acceleration and air pressure. Input signals to this computer were the measured rudder angles from the aircraft. Owing to there not being a lot of redundancy in the system and functions for error handling, many of the system's total integration tests were carried out via simulations with the aircraft in the loop.

Things discovered included problems with play and friction in the controls from the rudder servo to the rudder, which was difficult to model.

Among the last things discovered was that flight paths were skewed when simulating testing sites in the north. The effects were not noticed during simulator flights in the Linköping area, and were only noticed when simulating in areas around the testing sites in Vidsel. This was due to the fact that meridian convergence is more pronounced further north and an inappropriate conversion between the two coordinate systems - WGS84 and RT90.

Testing equipment was transported to the test site in order to verify a new software version if the need arose. The need to develop a new software version was avoided owing to the possibility afforded by changeable parameter files. The possibility provided by Flight Test Function proved sufficient.

Midcas Technology Demonstrator

Flights with SHARC demonstrated the potential for autonomous flights. By building a system for critical avionics with requirements similar to Gripen's control systems would make it possible to construct safe aircraft that satisfied the corresponding flight safety requirements.

It still remained to be shown how these types of aircraft would be able to fly in the same airspace as piloted aircraft. For this reason, a pan-European programme was initiated under Saab's leadership to define how unmanned aircraft could be introduced in a safe manner. This was the beginning of project MIDCAS (Mid Air Collision Avoidance System).

In order to demonstrate the possibility of realising a system able to autonomously detect and avoid other aircraft in the same way as piloted aircraft, a system was defined, built and flight tested.

Requirements were collated and simulations carried out in the MIDCAS project to demonstrate that the simulations and algorithms created were able to test interaction with existing control of civilian airspace, ATC. The final simulations to demonstrate a safe function such as this primarily covered automatic batch simulations (type "Monte Carlo").

ADS-B was used to detect interacting aircraft along with a query function via IFF, similar to other aircraft. In order to detect aircraft in the same way as pilots, electro-optical sensors, infrared sensors, and radar were used.

MIDCAS concluded with successful test flights in May 2015.

The author´s reflections