Yeah, just sum it up, but Barid did it very well right now.

My 15 first years of career were between the following two intricate lines of LTA design and LTA operations.

It started as a hot air balloon which opened me to the experience of being a blimp, a 5,000 cubic meters machine made 50 years back.

And to the design and test flights of the small solar powered prototype which incidentally brings me here today by the interest of Christophe.

And I spent long years at Flyingways addressing the issues you raised earlier, raising and addressing them.

I trust they have done much more work since I left the company up to my current position as a testing engineer for different kind of aerostats from the stratosphere to the aerostats.

I'll be speaking about testing not in a detailed methodology but rather an open perspective and a purpose and hints of testing strategy.

To start with, the words of one of the French aviation pioneer which summed up quite well.

Designing a flying machine is nothing, did he say, building it is not much but flying it is everything.

This was the times where they were inventing what an airplane is. So to put some perspective.

This brings me to a first definition of testing that would be that you have to verify that the aircraft behaves as expected to complete the flight in terms of stability, in terms of controllability and in terms of safety.

Which is basically the very beginning of the process of certification.

Even if it did not have this word yet at that time which helps you to ensure that you have what it takes to bring yourself down safely and minimizing harm to others if something bad happens.

This is summed up in this synoptic diagram of the forces of light which is I think quite common between heavier than air with lighter than air.

Certification is today easily perceived as a break because it takes work, it takes cost, it takes attention and it makes things not as easy as expected.

But I'd like to focus on two other forces which are related.

How do you get a loft? You need money.

And to get money you need a purpose, you need a mission, you need a job to do to pay for that.

And this brings me to another aspect of testing which is that you have to verify that the aircraft meets the requirement to complete your mission.

That's where we are speaking of performance, we are speaking of speed, of payload, of consumption, of range and of whatever is specific to your mission, to your model.

And you have to reach that in the expected range of costs because that can be a killer.

So I would just add a line to the saying of Captain Ferber, designing is nothing, building is not much, flying is everything but achieving the job is the essence of it all.

Let me talk about testing strategy and make a step back on what is a relevant test.

Any test by principle, by definition, can lead to a redesign, to a reproduction, to retesting, to repaying.

So an early test is a cost-effective test.

But on the other end, validation has to be on a representative system in representative conditions to be relevant.

So a design-efficient test is a late test.

Building a testing strategy is addressing this compromise.

And I focus on three hints to help on that.

The first hint is the designer's mindset.

We are speaking of quite new concepts, quite adaptations of an old idea to a new environment, industrial environment, economic environment.

So the testing strategy must drive the whole development from the very beginning in the mindset of the design team.

Having in mind, you all know Murphy's load, what can go wrong will go wrong.

So having this little voice in head constantly in terms of risk and uncertainty management.

So I wrote down a few questions that were in my mind when I was a design engineer.

What is new in my concept? How do I expect it to work?

How could it not work as I expect? What could go wrong in the environment, in the design, in the way of using it?

And that's the last thing is the very reason why I like lighter than air.

Building a balloon, we are building a part of the atmosphere.

When we take the air, we become a little bubble of atmosphere.

So we are giving Mother Nature a toy. She will have fun with it.

How? What will happen? What in the environment, in the sun, in the cloud, in the wind, in the turbulence?

What will affect my business? What will affect my operations? What will affect my business plan?

So this is a mindset of questions that have to be always present when thinking about a new LTA project.

The second hint, I feel a little bit like Captain of Views saying so, but it will be decomposition.

We have new things. We have a new concept. We have a new system.

If I have to redesign it all, this is a high impact, high financial impact and high expenses according to the outcomes.

Decomposing the complex new situation in elemental uncertainties in the environment, in a new concept of a part of the system,

in the way of using a part of the system as well.

So decomposing this uncertainty and defining ways of de-risking it at a lower impact scale.