How to Build An Aircraft? | Grazia Vittadini | The Revamped Founder

You have the lift produced by the wings. That lift, if you're flying nice and steady, is balancing the weight of your aircraft. And as you're flying forward, it means you have enough thrust coming from the engine to at least be equal to the drag your aircraft is experiencing. The lift effect is linked to the role of aerodynamics. First of all, even if you're talking about rotorcrafts or typically helicopters, their blades have exactly the effect of a wing, creating that marvelous vertical-oriented force which is called lift.

Hey, hi. Yes, I'm very, very happy to be here today. Thanks for having me on your podcast.

Yes, indeed. My mother told me that the first word – I was born in Italy – so my first word was 'mama', which means mother. My second word was 'papa', which in Italian can be both father and food. And the third word apparently was 'aeroplano'. So I was very attracted to things that fly since a very, very tender age.

Nobody really knows. I have always been very attracted by objects in the sky. My father used to read me stories before I would go to sleep about great explorers, adventures, and also aviators. Being born in Milano, the city where Leonardo da Vinci spent a lot of time, we would go every year to the Museum of Science and Technology and see all his wonderful machines and the collection of airplanes. So it was something I always had a curiosity for. At some point, I even wanted to be a fighter pilot, but at that time in Italy, it was not allowed for women to fly in the Italian Air Force. So I decided: if I cannot fly these airplanes, I will build them. That prompted me to go to engineering school. I am an aerospace engineer specialized in aerodynamics, but I have worked most of my years on the structure side of aircraft and also worked on satellites in space for a short period. The majority of my professional journey has been in building airplanes, and since two years I moved to Rolls-Royce, where it's no longer the airplane but the engine that is the most fundamental system on board an aircraft.

There are different categories of vehicles. Airplanes, rotorcraft – helicopters – gliders, lighter-than-air like balloons or airships. The major ones are airplanes and rotorcraft. Interestingly, satellites also fly. In engineering jargon, when a satellite is launched and goes into orbit around the Earth, we say it is flying, even though the air is so thin there is virtually no lift. An aircraft can float in the air only by constantly moving forward, so that the wings generate lift. As altitude increases, air becomes thinner, so the airplane needs to go faster. At very high speed, a centrifugal force contributes to staying afloat, which is the virtual force that keeps satellites in circular orbit. When the altitude increases, the speed to generate lift increases until the centrifugal force dominates, and the aircraft becomes an orbiting spacecraft. There is a theoretical line called the Kármán line, 100 km above Earth, considered the boundary of space.

Typically above the edge of space, you have to have a speed enough to keep you afloat – you are basically orbiting. As a rule of thumb, airplanes fly in the troposphere up to about 20 km. Weather balloons can go to the stratosphere up to 50 km. Then up to 85 km is the mesosphere, and at about 100 km is the Kármán line. Above that, in the thermosphere, the International Space Station orbits at around 400 km. So that's the structure of the layers between outer space and Earth's atmosphere, which is quite difficult to escape.

Very different design principles. I came from building airplanes and went to working on satellites. One thing that surprised me is that satellites need to be first-time right, first-time perfect. They must resist incredible vibrations and accelerations during launch, then deploy solar arrays and antennas, and everything must work impeccably. Then the satellite stays in orbit and needs to work for decades with no maintenance. In contrast, airplanes can land and be adjusted. Satellites sustain strong vibrations during launch and extreme temperature excursions – from very hot on the sun side to very cold in the dark. It's a unique set of challenges. For airplanes, it's not a walk in the park either. Requirements depend on the mission: transport, utility, aerobatics. You need to have the mission in mind and derive requirements from it.

Space debris is a big topic because debris orbiting Earth has speeds much higher than a bullet. It's extremely dangerous for the International Space Station, satellites, or exoplanetary missions to be hit. Currently, space is still pretty empty, and debris about 10 cm in size is monitored. If a satellite is on a collision course, it can perform an avoidance maneuver. But sometimes satellites explode or collide, creating clouds of debris. With more satellite constellations, the level of debris will increase. So it's a mission that will become more and more relevant – not only to avoid debris but also to collect it so it doesn't become a hazard.

For airplanes, there is one fundamental principle: airworthiness, strongly linked to safety. Airworthiness is the aptitude of an aircraft to fly safely in all conditions for which it was designed. You can't just build an aircraft and supply it without permission. There are aviation authorities – FAA, EASA, etc. – with certification rules you must comply with. If you want to build something that doesn't exist yet, you work with the authorities to demonstrate safety. Then you do market analysis and requirements, many iterations and trade-off studies to decide technologies, structural concepts, system architecture. You simulate rather than build and test wrong. After preliminary sizing, you go into detail design, define parts and interfaces. Then production and assembly. The first aircraft are used for testing – structures, loads, flying cycles. Testing is a big part of qualifying. Then first flight, and you check that the aircraft behaves as predicted. If not, you iterate. You also test scary stuff: shooting birds with a bird cannon to show you can still land safely, testing in extreme cold and heat, even getting hit by lightning. It's a very extensive testing program, taking up to 10 years from first pencil to entry into service.

The thing in common across all aircraft are the laws of physics. Specifically, the lift effect, linked to aerodynamics. It's important to understand the difference between the role of an engine and a wing. The engines produce thrust to move the aircraft forward, making air flow over the wings. The wings deflect air downward, generating an upward force called lift, overcoming weight. In steady flight, there is a balance of forces: lift balances weight, thrust balances drag. The wing shape – the airfoil – is fundamental. Airflow attaches to the curved upper surface, creating low pressure above and high pressure below, giving lift. Engines themselves are incredibly complex. They have a fan that sucks in air, most of which bypasses the core. The core compresses air, burns fuel, and drives turbines that spin the fan. The bypass air provides most of the thrust. Engines can be enormous – the fan diameter over 10 feet, sucking in almost 4,000 pounds of air per second. The temperature in the combustor is higher than molten lava, requiring cooling channels in turbine blades. Engines are the most expensive part of an aircraft; sometimes planes are cannibalized just for the engines.

It all depends on the rating of the engine. For example, the Rolls-Royce Trent XWB powering the A350-900 has a variant producing 84,000 pounds of takeoff thrust, and for the A350-1000, a variant producing 97,000 pounds. You size the engine based on the maximum takeoff weight of the aircraft.

Teleportation. Once we will be able to – the problem is the proton, mass transporting virtually mass is complicated. But maybe one day teleportation will become a reality, and then we will make ourselves as engine and airplane manufacturers redundant.

Well, thank you very much for the chat this week. I'm looking forward to listening to other super interesting podcasts of your revamped Founder Thetion. Thank you.