Torsten Broesigke job is stressful. However before you shed a tear, you should know that ‘stress’ is his job.
His job is to predict and calculate how various forces affect materials and structures used in aeronautics,
balancing weight reduction and stability. We met up with Torsten to find out more about his role.
Mr. Torsten Broesigke
What is the most stressful part of being a stress engineer?
It is making sure the calculations required for the construction phase are ready in time.
Adhering to deadlines in order for the airplane to safely manoeuvre through the air is our
main assignment. This includes a vast array of both mathematics and physics calculations.
Usually this is achieved with the help of the Finite Element Method (FE) by which a computer programme simulates
a structure. All forces (expansion, tension, etc.) are calculated by the programme. Of course, all Airbus
aircraft are physically tested in all parts, as certification requires, but at this stage of the process,
we use virtual tests, which take a lot of time and cost out of the development process. Each part to be
constructed is subjected to the computer programme before manufacture. The aim is to minimise weight and
maximise stability. My job is largely about calculating the structure of an aircraft’s tail unit impacted
by air loads.
What are the three most important prerequisites for your job?
An important prerequisite is a good command of spoken English, as well as a very good knowledge of Mathematics!
And – needless to say – you need a degree in engineering. I am a civil engineer by discipline, with a strong
personal background in statistics, mathematics and physics with an emphasis on mechanics. Another very
important point is the desire (and ability) to document your work properly.
This is actually very important, as other colleagues need to be able to interpret your findings accurately in
order to complete their work. Flexibility is paramount as you often need to cooperate with other departments
including load simulation, finance, construction and many more. It is often necessary, to push the material
to the extreme limit. These limits have to be quantified which is achieved via computer simulation. The details
are very complex and you need to be able to keep an eye on the whole process. Additionally to that, it is an
advantage to have a strong knowledge in material technology (such as carbon fibre) and how they react under
various conditions such as heat, frost, damage impact, torsion and so forth.
Which aspects of your daily work will gain importance over the next five years? And which will decline?
What will decline: The work we will have to put into the development of the A400M will certainly decrease as
we are nearing the end of the development phase. The next five years, however, will see a strong need for
documentation of the work we have done over the past few years. A number of additional calculations will
probably be required for the empennage along the way to make sure we have done everything right.
What will increase in importance: After we have completed the pre-production phase and all measures
have been signed off, stepping into serial production comes into sight. Before this particular gateway
we only use pre-serial parts. From here on it is important to achieve serial production maturity for the
What is the most obvious difference when working in cross-culturally assembled teams?
The people coming from different cultural backgrounds usually have different ways of solving problems.
It is actually quite interesting to observe how it develops during the daily work day after day.
I tend to believe that a typical German like myself thinks more in terms of limitations, whereas
Spanish, French or Italian colleagues think in terms of opportunities. I am always amazed by their
communicational skills. As English is our common language and the command of the language is very
high throughout the team, we can usually achieve outstanding results. An interesting difference in
the procedure is: Germans tend to write e-mails, whereas colleagues from other countries prefer to
pick up the phone and talk things over.
What typical software products do you use most?
Microsoft Office, especially Excel und Visual Basic (for smaller routines) as well as MSC Patran Nastran
(FE Programmes). The most common programming language is Fortran. Candidates wanting to pursue a
career in aeronautical engineering usually master this kind of software with ease.
Do you have a preference for either the analysis of mechanical systems (like a rotor) or do you prefer the more intimate examination of an aircraft’s ‘skeleton’?
Both aspects are very rewarding. Right now, my work is mainly geared towards the structure, the skeleton of
an aircraft if you will. In my position I am specifically responsible for the structure of the VTP
(vertical tail plane). That doesn’t mean I have no contact with the team working on the mechanical
and electrical systems, but it is not my area of responsibility.
What is the most exciting phase of an aircraft development programme for you and does the size of an aircraft have a direct impact on the stress parameters or is this merely a linear function?
The dimensioning phase is the most interesting phase. This is where it all comes together. We
usually receive the outer shape of the vertical tail and then fill it with all the necessary details
so the part can be produced. This is actually my favourite phase of the construction process as there
is an immense amount of detail to be taken into account. And obviously the sheer size of an aircraft
does have an enormous impact on the forces being calculated.
Are you involved in the test-flight routines as well?
Not directly. The stress analyst is like a customer of the real life testing routines.
Usually the test aircraft executes manoeuvres that would be very difficult to compute
(for example the impact of wake turbulence).
What parameters are used to determine real testing versus computer simulation?
Most loads are created and calculated with the help of wind tunnel models. At present,
wake turbulence is still quite difficult to simulate. As a result these forces are often
tested in test flights. Strain gauges are used to measure the effects that the various
forces have on the structure. In military aircraft programs this kind of routine is quite
common, but in the civilian sector it is relatively new. We scrutinize results predicted
via computer with the actual results measured in the aircraft when performing the test
programme. The basic effects of such in-flight manoeuvres can be calculated in computer
simulations, but not all the data we require. So real testing is the only way to acquire
When looking at the various dimensions of analysis (static, dynamic, fatigue, damage tolerance,
fluid mechanics or thermal) what is the most demanding factor or dimension?
Damage tolerance is the least predictable task. There are numerous parameters influencing
the way in which damage occurs. Heat, moisture, the position of the part in question,
materials adjacent to the part, air pressure, and age can all be influential. It helps
to be an experienced engineer, but you can’t relinquish life testing. It is mandatory.
Is linear analysis always less complex than non-linear?
Yes. But that does not mean they are not complicated at all. Calculating non-linear processes
requires scrutiny of damaged material and changes in stiffness. That is much more complex than
calculating the forces impacting materials in linear processes. Environmental conditions like
heat or moisture can alter the way in which a certain material will react to loads. All these
parameters change the outcome (i.e. deformation) of parts in question. This is why the task in
linear processes is slightly less complicated than in non-linear. Non-linearity just multiplies
the options of the material to react.
What advice would you give students who want to become stress engineers?
If you want to start working with EADS you should be one of the best in your class. And always
keep the following in mind: Whatever you develop and plan to do, it has to be feasible.
That means someone has to be able to physically build it.
Which technology, methodology or material do you consider world-class in your field of work?
Clearly that is composite material. Airbus is a world leader in this area. The numerous innovations
we have been able to bring to market in the past and continue to do so today are the result
of a broad and deep knowledge base. This knowledge helps us to precisely predict how
advanced materials behave under loads and environmental conditions.
What is special about your job on the A400M programme (complexity, innovation, military, leading-edge product)?
Besides certain flight-manoeuvres in testing of military aircraft that are uncommon for civil aircraft, -
so they were new to me and to the team - the particular specialty of the assignment we currently are working on
is the fact that this shape (the T-Tail) is a novelty for Airbus. This might seem unusual, as T-shaped tails have
been in use for quite some time in other EADS divisions, but it was the first time for Airbus to use this particular
tail unit shape.
The building, testing and documentation to develop our knowledge base were both very challenging and very rewarding.
Why does the A400M have a top-positioned horizontal tailplane and which impact
does it have on the overall VTP development, engineering and manufacturing process?
Airflow and inertial forces apply to the tail unit. The T-shape enables a more stable flight attitude and it is easier for
loading and unloading, including air drops and keeps the HTP (horizontal tail plane) outside the
airflow produced by engines and wing. The use of composites in aeronautics is truly innovative
and cutting edge technology. The parts are manufactured from several layers and then cured together.
It is quite different from the technology used in the automotive industry. The biggest advantage
is the increase in potential payloads. Everyone working with composites enjoys being involved in
cutting edge technology that will ultimately benefit millions of people around the globe – be it on earth,
in the sky or in space.