AirShaper

Parts in the NASA interview series:
- Part 1 - New aerodynamic concepts: https://youtu.be/m4rysu8LlLM
- Part 2 - Propeller design: https://youtu.be/UDZBqDQGU8o
- Part 3 - Battery and component cooling: https://youtu.be/ieB541felas
- Part 4 - Electric flight experience: https://youtu.be/pGn07UTVKBg

In this third part of our video interview series with NASA on the X-57 Maxwell Electric Aircraft, we dive into the details of cooling.

The X-57 requires around 90-100 kW in cruise versus 250 kW during take-off. This variation in loading strongly determines the sizing, the cells, the layout etc. of the battery.

Everything is directly air cooled on the airplane. The battery is passively cooled. The cooling of the inverters and motors poses quite a big challenge. They reach their operating temperature within seconds, so it's important to minimize the amount of rejected heat as well as understanding the cooling requirements across the flight envelope.


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The AirShaper videos cover the basics of aerodynamics (aerodynamic drag, drag & lift coefficients, boundary layer theory, flow separation, reynolds number...), simulation aspects (computational fluid dynamics, CFD meshing, ...) and aerodynamic testing (wind tunnel testing, flow visualization, ...).

We then use those basics to explain the aerodynamics of (race) cars (aerodynamic efficiency of electric vehicles, aerodynamic drag, downforce, aero maps, formula one aerodynamics, ...), drones and airplanes (propellers, airfoils, electric aviation, eVTOLS, ...), motorcycles (wind buffeting, motogp aerodynamics, ...) and more!

For more information, visit www.airshaper.com

Electric Aviation - NASA interview on Maxwell X57 - Part 3: Battery and Component Cooling Design

Parts in the NASA interview series:
- Part 1 - New aerodynamic concepts: https://youtu.be/m4rysu8LlLM
- Part 2 - Propeller design: https://youtu.be/UDZBqDQGU8o
- Part 3 - Battery and component cooling: https://youtu.be/ieB541felas
- Part 4 - Electric flight experience: https://youtu.be/pGn07UTVKBg

In this second video in our series with NASA, we dive into the details of the propellers and how they compare to other propellers seen on e-VTOLs for example.

The X57 features two very distinct propellers:
- High lift propellers: these increase the local airflow speed around the wing, providing it with more lift. They aim for a uniform flow velocity to create a predictable and reliable increase in lift.
- Cruise propellers: these are aimed at maximum efficiency and feature a higher axial flow speed at the tips of the propellers


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The AirShaper videos cover the basics of aerodynamics (aerodynamic drag, drag & lift coefficients, boundary layer theory, flow separation, reynolds number...), simulation aspects (computational fluid dynamics, CFD meshing, ...) and aerodynamic testing (wind tunnel testing, flow visualization, ...).

We then use those basics to explain the aerodynamics of (race) cars (aerodynamic efficiency of electric vehicles, aerodynamic drag, downforce, aero maps, formula one aerodynamics, ...), drones and airplanes (propellers, airfoils, electric aviation, eVTOLS, ...), motorcycles (wind buffeting, motogp aerodynamics, ...) and more!

For more information, visit www.airshaper.com

Electric Aviation - NASA interview on Maxwell X57 - Part 2: Propeller Design

Learn more about the design of the Lightyear One:
https://youtu.be/TKHjyC_L0OM

In this video, we walk around the Lightyear One solar car to analyze its aerodynamic features (it has a drag coefficient below 0.20!).

We also interview Tom Selten, the Chief Business Development Officer of Lightyear. He was the team manager of the winning Eindhoven solar race team in 2015. They raced Stella Lux, which was a family car for 4 people which triggered the Lightyear adventure.

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The AirShaper videos cover the basics of aerodynamics (aerodynamic drag, drag & lift coefficients, boundary layer theory, flow separation, reynolds number...), simulation aspects (computational fluid dynamics, CFD meshing, ...) and aerodynamic testing (wind tunnel testing, flow visualization, ...).

We then use those basics to explain the aerodynamics of (race) cars (aerodynamic efficiency of electric vehicles, aerodynamic drag, downforce, aero maps, formula one aerodynamics, ...), drones and airplanes (propellers, airfoils, electric aviation, eVTOLS, ...), motorcycles (wind buffeting, motogp aerodynamics, ...) and more!

For more information, visit www.airshaper.com

Lightyear One - Solar Electric Vehicle - Walkaround & interview

Parts in the NASA interview series:
- Part 1 - New aerodynamic concepts: https://youtu.be/m4rysu8LlLM
- Part 2 - Propeller design: https://youtu.be/UDZBqDQGU8o
- Part 3 - Battery and component cooling: https://youtu.be/ieB541felas
- Part 4 - Electric flight experience: https://youtu.be/pGn07UTVKBg

In this first out of 4 videos on our interview with NASA, we discuss the basic layout of this novel electric aircraft.

The X-57 is the latest in the famous series of X-planes developed by NASA - their experimental aircraft like the X15.

Sean Clarke and Nick Borer give their take on the design of this aircraft. We discuss the benefits if distributed electric propulsion, especially in terms of new aerodynamic concepts that are being made possible.

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The AirShaper videos cover the basics of aerodynamics (aerodynamic drag, drag & lift coefficients, boundary layer theory, flow separation, reynolds number...), simulation aspects (computational fluid dynamics, CFD meshing, ...) and aerodynamic testing (wind tunnel testing, flow visualization, ...).

We then use those basics to explain the aerodynamics of (race) cars (aerodynamic efficiency of electric vehicles, aerodynamic drag, downforce, aero maps, formula one aerodynamics, ...), drones and airplanes (propellers, airfoils, electric aviation, eVTOLS, ...), motorcycles (wind buffeting, motogp aerodynamics, ...) and more!

For more information, visit www.airshaper.com

Electric Aviation - NASA interview on Maxwell X57 - Part 1: New Aerodynamic Concepts

To learn more about CFD simulations: https://youtu.be/dyiREvdc4Gg

F1 in schools STEM challenge is a global competition in which students can design miniature F1 cars to race in straight lines. The cars are propelled by CO2 cartridges.

In this video, the Redline Racing team of the Parramatta Marist High School in Sydney explains how the competition works and how they used AirShaper to optimize their design.

To apply for the "AirShaper F1 In Schools" package and improve your F1 in schools car design, please visit:
https://airshaper.com/f1-in-schools


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The AirShaper videos cover the basics of aerodynamics (aerodynamic drag, drag & lift coefficients, boundary layer theory, flow separation, reynolds number...), simulation aspects (computational fluid dynamics, CFD meshing, ...) and aerodynamic testing (wind tunnel testing, flow visualization, ...).

We then use those basics to explain the aerodynamics of (race) cars (aerodynamic efficiency of electric vehicles, aerodynamic drag, downforce, aero maps, formula one aerodynamics, ...), drones and airplanes (propellers, airfoils, electric aviation, eVTOLS, ...), motorcycles (wind buffeting, motogp aerodynamics, ...) and more!

For more information, visit www.airshaper.com

F1 in schools  - Aerodynamics

To learn more about CFD simulations: https://youtu.be/dyiREvdc4Gg

Rotating Wall Boundary Condition
The simplest form is the rotating wall boundary condition. Without rotation, the velocity of the airflow is always zero at the surface because of the no slip condition. The rotating wall boundary condition simply enforces a tangential velocity onto the surface of the rotating object. This velocity is equal to the distance from the center multiplied by the rotational velocity. The further you move away from the center, the higher the velocity.
This technique is very simple and doesn’t significantly change the cost of computation, as no extra equations are introduced and the flow can be solved in a steady state manner. It’s very suitable on surfaces that are tangential to the local direction of rotation.
At AirShaper, we chose this technique to take the rotating wheels of cars into account, as it’s a very robust solution. When you click a tire, the axis of rotation will be detected automatically, the components inside will be selected as well and the rotational velocity is automatically linked to the driving speed of the vehicle

MRF – Multiple Reference Frame
For more complex geometries with a lot of non-tangential surfaces, the more advanced MRF technique can be used. It stands for multiple reference frames. In essence, you create a separate region around the rotating object. Inside this region, for each point, you calculate the relative velocity, which is a combination of the absolute velocity and the rotational velocity.
The Navier-Stokes flow equations are then built on top of this relative velocity, which results in extra terms that take the Coriolis and centrifugal forces into account. So, you end up with a set of equations for the stationary region and another set for the rotating region.
This method is a bit more expensive in terms of computational cost, but still allows for steady-state calculations and it’s able to accurately capture the “instantaneous” flow pattern around a propeller for example.
At AirShaper, we chose to use this technique when adding rotating propellers to a simulation. When selecting a propeller, the central axis will automatically be detected. The direction of rotation can be flipped and the RPM can be set by the user. And it is possible to add multiple propellers to a single simulation 

AMI – Arbitrary Mesh Interface
This instantaneous flow, however, can depend heavily on the relative position of the rotating part versus the static part, like a propeller versus a strut. So, for very advanced simulations, there’s also the AMI technique, which stands for arbitrary mesh interface. In this technique, the mesh around the rotating object is actually cut and then made to rotate. This can only be done using transient simulations, as the rotation of the mesh is now linked to the actual time step. At the sliding mesh interface, the cells of the stationary and rotating mesh exchange information on the flow.

This technique is usually the most accurate, but also very demanding in terms of computational effort. It can also be challenging in terms of stability, as the mesh interface needs to be defined very well. This type of simulation usually requires a manual approach.


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The AirShaper videos cover the basics of aerodynamics (aerodynamic drag, drag & lift coefficients, boundary layer theory, flow separation, reynolds number...), simulation aspects (computational fluid dynamics, CFD meshing, ...) and aerodynamic testing (wind tunnel testing, flow visualization, ...).

We then use those basics to explain the aerodynamics of (race) cars (aerodynamic efficiency of electric vehicles, aerodynamic drag, downforce, aero maps, formula one aerodynamics, ...), drones and airplanes (propellers, airfoils, electric aviation, eVTOLS, ...), motorcycles (wind buffeting, motogp aerodynamics, ...) and more!

For more information, visit www.airshaper.com

How to model Rotating Elements in CFD (computational fluid dynamics) using MRF, AMI and more

Check out Fluid Mechanics 101:
https://www.youtube.com/channel/UCcqQi9LT0ETkRoUu8eYaEkg

On Aidan's channel, you can also find the uncut, full length video of this interview:
https://youtu.be/Ntl15C2KXCQ
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For this video, we interviewed Aidan Wimshurst, who did his PhD at Oxford University (United Kingdom) on Tital Power Generation.

Concept
Tidal currents originate because of the tides: as water levels change, water flows from one area to another. When the water needs to fit through a narrow channel or move around certain coastlines, flow speeds can be quite high. These streams are very predictable, which makes it much easier to integrate the energy they produce into the grid.

The general idea is to take a typical 3-bladed wind turbine and put it under water. But there are a number of key differences to wind turbines that make tidal turbines unique.

Wing tip vortex
On an airplane, the air at the high pressure location below the wing wants to move to the low pressure location at the top of the wing via the side (the wing tip). This creates a curling motion called wing tip vortex.

On a turbine, this vortex also exists but it leaves a spiral trace instead of a linear one. And this increased vorticity & turbulence can impact turbines further downstream. It also represents efficiency losses for the turbine itself, which is why some (wind turbine) blades are equipped with winglets.

Cavitation
If pressure is reduced below the vapor pressure, you will start getting bubbles. When these implode, they can cause serious damage to the blades, structure, and so on. The risk of cavitation is reduced when the hydrostatic pressure is high, close to the sea bed. But close to the surface, this hydrostatic pressure is much lower, increasing the risk of cavitation. So the risk of cavitation varies along a single revolution.

Farm layouts
For a given plot of land, the goal is to maximize energy and thus put as many turbines as possible in place. But if you put them too close to each other, the turbulent wake of one turbine will lower the efficiency and lifetime expectancy of other turbines, so there is an optimum to be found.

With tidal energy, the orientation of the flow is always the same, only changing direction between tides. So these are typically placed in an array. The flow around a turbine is accelerated, meaning that a turbine placed in this accelerated flow will yield more power, ánd the original turbine will also perform better. This is called constructive interference. This will be analyzed in the MeyGen project.

Size trends
Compared to wind turbines, the constraints are different for tidal energy. The water depth is typically between 20 and 50 meter, so that limits the rotor size. Also, the velocity shear (difference between the velocity at the bottom and free water surface) poses strong bending loads on the rotor.

Suitable sites
Tidal energy will never be able to provide the full energy demand of a country, but it can provide a valuable contribution. And it's also very useful for remote sites, which are typically islands, as they have difficult access to other sources of energy.


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The AirShaper videos cover the basics of aerodynamics (aerodynamic drag, drag & lift coefficients, boundary layer theory, flow separation, reynolds number...), simulation aspects (computational fluid dynamics, CFD meshing, ...) and aerodynamic testing (wind tunnel testing, flow visualization, ...).

We then use those basics to explain the aerodynamics of (race) cars (aerodynamic efficiency of electric vehicles, aerodynamic drag, downforce, aero maps, formula one aerodynamics, ...), drones and airplanes (propellers, airfoils, electric aviation, eVTOLS, ...), motorcycles (wind buffeting, motogp aerodynamics, ...) and more!

For more information, visit www.airshaper.com

Tidal Stream Turbines - Renewable Energy from the Tides

- MV Agusta MotoGP - part 1: https://youtu.be/BUkaejkHRn8
- MV Agusta MotoGP - part 2: https://youtu.be/fGNdMaVft_w
- Motorbike wheelies: https://youtu.be/M2Z_GuLHmHs
- AMA superbikes: https://youtu.be/qrH_QBOrqbw
- Damon motorcycles - electric motorbikes: https://youtu.be/asYdvFfzHTs

For this video, we interviewed Derek Dorresteyn, CTO at Damon Motorcycles (https://www.damon.com).

Hyperdrive platform
The case of the battery is the main stressed component of the motorcycle, which means they got rid of the traditional motorcycle frame. It has reduced mass, the stiffness can be tuned and it provided more room.
Higher top speed, faster acceleration and far less rotating mass compared to an ICE motorcycle. It’s a really simple motor-gear reduction and this reduction in rotating mass significantly reduces the apparent mass, which otherwise adds forces that resist the vehicle leaning over and changing direction. Without the added forces, the bike feels much lighter in corner transitions.

Cooling
The electric drive train is far more efficient: 85% efficiency for the electric drivetrain versus 30% efficiency for the internal combustion engine. But the threshold temperature of a battery pack is much lower than that of a combustion engine, which again increases the required size of the radiator. Both more or less cancel each other out, meaning you end up with more or less the same radiator size.

Range
There is a lot of variability in the shape and size of the people that will be on the motorcycle, but also the way they interact with the bike can be different. For the optimization work in terms of drag, they have used a standard rider in terms of height and mass combined with the SAE J2982 drive cycle.

Aerodynamics
If they made a vehicle with the lowest possible drag coefficient, it likely would not be very commercial. So they have this tension between current design trends, consumer taste and the desire to improve aerodynamic performance.
The aerodynamics are extremely important: if they wouldn’t care at all, the range would just be half of the claimed 200 miles.

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The AirShaper videos cover the basics of aerodynamics (aerodynamic drag, drag & lift coefficients, boundary layer theory, flow separation, reynolds number...), simulation aspects (computational fluid dynamics, CFD meshing, ...) and aerodynamic testing (wind tunnel testing, flow visualization, ...).

We then use those basics to explain the aerodynamics of (race) cars (aerodynamic efficiency of electric vehicles, aerodynamic drag, downforce, aero maps, formula one aerodynamics, ...), drones and airplanes (propellers, airfoils, electric aviation, eVTOLS, ...), motorcycles (wind buffeting, motogp aerodynamics, ...) and more!

For more information, visit www.airshaper.com

How to Design Electric Motorbikes - Interview with Damon Motorcycles

For more information about:
- F150 coastdown testing: https://youtu.be/Gip3iG2A2zE

In this video, we’re going to improve the aerodynamics of America’s favorite pickup truck, the Ford F150. As a starting point, we used a highly detailed 3D scan of the latest version of the 2021 Ford F150, here in its hybrid version, provided by our partner A2MAC1. We uploaded this 3D scan directly to AirShaper, set the speed to 30 meters per second, added rotating wheels and launched a Regular Simulation.
A few hours later, we could immediately spot a number of problem areas in terms of aerodynamics:
- Right after the cabin, the flow separates and turns into a turbulent wake. Some of the flow tumbles down into the cargo bed and then hits the tail gate on the way out, again creating a wake.
- The huge mirrors are without a doubt very practical and safe, but they also generate a lot of drag.
- The underbody features many exposed components. That’s very practical for easy access and quick repairs, but it strongly obstructs the flow underneath the car, which creates resistance.
- The wheels look nice, but with their sharp edges and large openings, they create what is called ventilation drag – it’s the energy lost on mixing the air, which translates into extra drag. Also, they create dirty air which affects the aerodynamics of the car further downstream.
- The ride height of the car is quite high – great for off-roading, but usually not so good for the aerodynamics of a car, as more air is now travelling through the channel between the underfloor and the ground. And with the underfloor being so exposed, this can also create extra drag.
The verdict: a drag coefficient of 0.463. Not very impressive compared to for example the 0.21 of the Lucid Air.

So, the guys at A2MAC1 went to work, drew inspiration from the Tesla Cybertruck and came up with a number of improvements – let’s check them out and see how much they each reduce drag!
- First, the rear cover: by closing the cargo bed, the flow across and around the cabin now stays largely attached to the rear cover. The air is prevented from hitting the tailgate and now nicely slides downward to help reduce the wake behind the car. This solution alone lowers the aerodynamic drag by a staggering 14.82%! Optimizing this global shape of the car helps to improve what is called the pressure recovery: at the front of the car, the air hits the nose and creates a high pressure, pushing the car backwards. Once it has crossed the mid-point of the car, the flow starts to contract again. If you support the airflow in the right way, this helps to create a forward push, compensating for some of the drag at the front. The base shape of the Tesla Cybertruck offers a lot of potential in this regard, although the sharp edges might need to be tuned a little.
- Secondly, the F150 was given a smooth underfloor. This is something we also saw when we analyzed the Porsche Taycan and which applies to many electric vehicles: because of the electric drivetrain, it’s possible to create an almost entirely flat underfloor. This facilitates a much smoother and less turbulent airflow which strongly lowers the drag. In this case, a very crude underfloor design already lowered drag by 3.4%!
- Then, the aerodynamic wheel covers of the Tesla model 3 were pulled from A2MAC1’s database and, after some stretching and scaling, applied to the Ford’s wheels. Without any optimization, these cut drag by 2.23%.
- Another tweak meant taking off the side view mirrors altogether. Yes, in reality you’d have to put camera’s instead, if regulations allow it at all. But just to show the potential, we ran a simulation and noted a 5.5% drop in aerodynamic drag!
- Last but not least, the truck was lowered by 2 inches – this is a trick some other cars already apply to lower drag at cruising speeds. In this case, it lowered drag by another 2%. 

When adding all of these modifications at the same time, we observed a total reduction in drag of 25.05% - that is a massive difference! If we assume that aerodynamics are responsible for roughly half of the energy or fuel consumption of a car, then this means a 12.5 reduction in fuel consumption, or roughly 12.5% more range!


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The AirShaper videos cover the basics of aerodynamics (aerodynamic drag, drag & lift coefficients, boundary layer theory, flow separation, reynolds number...), simulation aspects (computational fluid dynamics, CFD meshing, ...) and aerodynamic testing (wind tunnel testing, flow visualization, ...).

We then use those basics to explain the aerodynamics of (race) cars (aerodynamic efficiency of electric vehicles, aerodynamic drag, downforce, aero maps, formula one aerodynamics, ...), drones and airplanes (propellers, airfoils, electric aviation, eVTOLS, ...), motorcycles (wind buffeting, motogp aerodynamics, ...) and more!

For more information, visit www.airshaper.com

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