As eVTOL projects move from the drawing board and simulation to physical components and flight, they need to be appropriately certified for commercial operation. Certification is a long and rigorous process, overseen by engineers like David Solar, Head of General Aviation and Vertical Take-Off and Landing at the <ExternalLink href="https://www.easa.europa.eu/en/regulations">European Union Aviation Safety Agency (EASA)</ExternalLink>. 

AirShaper was lucky enough to speak with David and discuss the challenges of certifying this new eVTOL breed of aircraft.

- ###### [What is an eVTOL?](#whatisanevtol)
- ###### [eVTOL certification](#evtolcertification)
- ###### [Certifying the powertrain](#certifyingthepowertrain)
- ###### [Certification differences between cargo and passenger](#certificationdifferences)
- ###### [Regulating vertiports](#regulatingvertiports)
- ###### [The future of eVTOLs](#futureevtols)

---

## What is an eVTOL? <a name="whatisanevtol"></a>

Urban air mobility is a developing concept that sees personal transportation take to the skies above our cities. Electric vertical take-off and landing (eVTOL) aircraft are the machines that will allow this to happen. 

- <ExternalLink href="https://verticalmag.com/news/airshaper-takes-fresh-approach-to-complex-field-of-computational-fluid-dynamics/">How AirShaper takes a fresh approach on eVTOL aerodynamics</ExternalLink>

An eVTOL essentially combines vertical and horizontal flight. They typically utilise propellors in the vertical position for take-off and landing, similar to a helicopter. Whereas for forward flight, some use the same propellors to generate lift and forward thrust, while others use horziontal propellors in combination with a wing. The simplest eVTOLs are small, light passenger aircraft that utilise electric motors to power the propellers with on board batteries to store energy. While the more complex eVTOL designs feature innovative propellor mechanisms and electric jet engines integrated into fixed wings. 

<ImageWithCaption
 src="/assets/images/archer-aviation-evtol-side-2.png"
 alt="Front view of a grey eVTOL that features vertical propellors and fixed wings"
 caption={
 
 The Midnight eVTOL from Archer Aviation combines propellors with fixed wings and is capable of flying up to 100 miles. CREDIT:{' '}
 <ExternalLink href="https://www.archer.com/midnight">
 Archer Aviation
 </ExternalLink>
 
 }
 width="700"
 height="378"
 positionCenter={true}
/>

---

## eVTOL certification <a name="evtolcertification"></a>

To certify an aircraft, governing bodies such as EASA, CAA (Civil Aviation Authority) and FAA (Federal Aviation Administration) work with manufacturers to establish a set of regulations that ensure the safety and airworthiness of an aircraft during design, manufacture and modification. The manufacturers then have to conduct comprehensive testing programmes to prove that their aircraft complies with these standards. 

- <Link href="/blog/cfd-in-passing-aircraft-easa-regulations#certifyingtodaysaircraft">How are today’s aircraft certified?</Link>

However, eVTOLs are a new type of aircraft with technologies and concepts that have never been certified before. Consequently, authorities are collaborating with manufacturers to write the rulebook on eVTOL certification.

<ImageWithCaption
 src="/assets/images/joby-aviation-evtol.png"
 alt="Side view of a stationery grey eVTOL from Joby Aviation"
 caption={
 
 Joby Aviation were the first eVTOL company to reach the second stage of FAA certification. CREDIT:{' '}
 <ExternalLink href="https://www.jobyaviation.com/news/joby-completes-second-stage-certification-process/">
 Joby Aviation
 </ExternalLink>
 
 }
 width="700"
 height="437"
 positionCenter={true}
/>

Although as David Solar explains, some standards can be carried over. “The certification of an eVTOL propeller is fairly similar to that of a conventional aircraft. But with eVTOLs you also have to consider the no single failure criteria and the application of the aircraft as the aerodynamic design is very much dependent on the aircraft’s objectives.” 

“For example, when transitioning from vertical to horizontal flight, depending on if it is a tilt or not a tilt, the propeller may stay in the airflow fixed at some point, so each propeller design is adapted to a specific aircraft configuration. Right now, there is no magic formula, manufacturers have to find the best compromise between performance, noise and aerodynamics.” 

However, with some of the latest eVTOL concepts utilising propellors for both vertical and forward flight, is the certification process different for a propellor used for take-off and landing vs a propellor providing horizontal thrust? 

“Yes, they each have different loading conditions which leads to different ways to not only design, but also to demonstrate that the propeller is fit for flight. There is not a 'one size fits all' solution, we evaluate the loading conditions as well as the fatigue tests and understand how these are used on the aircraft to arrive at the final certification," says David.

<ImageWithCaption
 src="/assets/images/joby-tilt-rotor-patent.png"
 alt="Diagram showing the mechanism of the Joby tilt rotor transitioning from vertical to horizontal"
 caption={
 
 Detail from the Joby tilt rotor patent shows a unique mechanism that requires bespoke certification. CREDIT:{' '}
 <ExternalLink href="https://www.atec-amt.org/uploads/1/0/7/5/10756256/atec_journal-fall20_112920.pdf">
 Aviation Technician Education Council
 </ExternalLink>
 
 }
 width="250"
 height="452"
 positionCenter={true}
/>

With urban air mobility such a novel industry, manufactures are constantly iterating their concepts to achieve the best performing designs. This has led to a huge variety of concepts, which make defining a set of standards that are suitable for all designs a real challenge. Furthermore, is there the danger that governing bodies could actually dictate the design direction through implementing certification standards? 

“Right now, everybody is coming with new ideas and at the end of the day the market will probably choose the ones that are most fit for purpose,” says David. “I think we will see some different designs according to the specific missions, but it won’t be hundreds of designs. Once we have visibility on the most popular concepts, we can then write specific guidelines for each type of eVTOL.” 

“We try to be as neutral as possible and not favour one design over another. That's why we have high level objective requirements that don’t consider whether a concept is a hovercraft or a plane because this prevents us introducing bias into the system. We don't know which eVTOL concept is going to be the best yet so we don't want to penalise a design by imposing requirements that may prevent some concepts achieving certification.”

---

## Certifying the powertrain <a name="certifyingthepowertrain"></a>

The eVTOL world has only ignited recently due to the capabilities of modern electric powertrains. High voltage batteries supply electrical energy to motors which power the rotors. However, vertical flight is an energy intensive process which requires a battery with a high energy density and therefore a high weight. This presents a conundrum for manufacturers: larger batteries provide the energy necessary to increase the range of an aircraft, but this additional weight requires more propulsion to keep in the air, requiring even larger batteries.

“It’s all dependent on the evolution of battery technology, but for now there is a trade-off between the payload and the range performance an eVTOL can achieve. This means that advances in the battery weight to power ratio will give the biggest increases in performance, although improvements in aerodynamic efficiency will still provide some gains, but these will be of much smaller magnitude," concludes David.

<ImageWithCaption
 src="/assets/images/lilium-evtol-battery-testing.jpeg"
 alt="Factory showing several battery testing machines at Lilium's headquarters"
 caption={
 
 eVTOL manufacturers are putting a lot of effort into researching suitable battery and cell technology. CREDIT:{' '}
 <ExternalLink href="https://lilium.com/newsroom-detail/liliums-battery-strategy">
 Lilium
 </ExternalLink>
 
 }
 width="700"
 height="394"
 positionCenter={true}
/>

---

## Certification differences between cargo and passenger <a name="certificationdifferences"></a>

The battery energy density vs payload question also depends on whether the aircraft is intended for transporting passengers or cargo, as each scenario demands very different energy requirements and thus affects the achievable range. 

“One of the big cost drivers at the moment is when manufacturers will change the battery,” says David. “The likes of Volocopter are willing to swap the battery, recharging them in a very low, steady controlled environment so that the battery is in perfect condition for charging. While others are looking at solid-state batteries that could have less of an impact on ageing.”

The different flight paths of cargo and passenger aircraft also means different certification requirements, as David explains. “If you are operating your cargo not over cities, then you can have lower security using the battery basic category that we have defined in our special condition window. There are differences in some of the redundancies especially if you go to the very low end of the basic category where you also have differences in terms of software development. It may be that you can have only an emergency landing requirement in the basic category because we consider that you will be flying over some non-congested, hostile environment so you could find a spot within a reasonable amount of time to land.”

“However, if you are operating passenger commercial flights, the level of safety in Europe, means manufacturers have to comply with an 'enhanced category' which is the highest of safety level we have today. This also applies to cargo if you are operating over what we call congested sites, over cities or environments. In these cases, we are requesting that you are carrying on the flight even with a failure to an alternate destination. These differences have a lot of design implications behind them.”

<ImageWithCaption
 src="/assets/images/charging-evtol.jpg"
 alt="Side view of a white eVTOL plugged in and charging on the runway"
 caption={
 
 Fast charging is good for aircraft turnaround times, but damaging for battery ageing. CREDIT:{' '}
 <ExternalLink href="https://aviationweek.com/business-aviation/beta-outlines-evtol-charging-considerations">
 Aviation Week
 </ExternalLink>
 
 }
 width="700"
 height="467"
 positionCenter={true}
/>

---

## Regulating vertiports <a name="regulatingvertiports"></a>

Flying across the skies of our cities does not only cause safety concerns, but EASA also have to consider the operational noise of busy vertiports or landing sites and the impact this will have on the people living there. With no eVTOL certified to fly commercially yet, EASA have had to conduct comprehensive research to understand the challenges of certifying vertiports. 

<ImageWithCaption
 src="/assets/images/evtol-melbourne-skyline.jpeg"
 alt="Graphic showing several eVTOL aircraft flying over the Melbourne city in Australia"
 caption={
 
 Busy airspace above cities will be a contentious issue for inhabitants. CREDIT:{' '}
 <ExternalLink href="https://www.aviationtoday.com/2022/09/06/experts-discuss-investment-opportunities-advanced-air-mobility-australia/">
 Avionics International
 </ExternalLink>
 
 }
 width="700"
 height="350"
 positionCenter={true}
/>

“There is no noise level which has been defined so far, but we are taking measurements. It's not like a helicopter or aircraft where you have ideal noise limits which are already set up. It is so new and we don't yet know in detail the noise profile of these machines, so we are learning by doing,” highlights David. 

“For sure they will be quieter than a helicopter and also companies know that noise is critical for public acceptance. I think the quieter the aircraft, the more successful it will be with the public. So there is a strong incentive for companies to minimise the noise footprint. We'll see later down the road if we have to put in some limits, maybe in cities or other environments, but so far, we are gathering data and taking the time to think about it.”

---

## The future of eVTOLs <a name="futureevtols"></a>

There are very few knowns about the way the urban air mobility concept will evolve over the next decade but organisations like EASA are at the forefront of defining how eVTOLs will become a part of our daily lives, safely. 

“It will depend on how the industry is adopted by consumers. It will be expensive at the beginning, so unlikely to be used by most individuals. The price of eVTOLs will likely exceed that of cars, because of the high battery costs and also the pilot will need to be trained as well as licenced. Longer term, costs may reduce if production can be scaled up and the operational requirements are lowered so you don’t need a pilot to fly the aircraft. I still think it will be challenging to reach the current automotive industry levels of production and cost.” 

<ImageWithCaption
 src="/assets/images/evtol-concepts-diagram.jpg"
 alt="Diagram showing the multirotor, lift and cruise, tilt rotor and ducted vector thrust eVTOL concepts"
 caption={
 
 Not all of the different eVTOL concepts will survive, but nobody knows which will succeed. CREDIT:{' '}
 <ExternalLink href="https://lilium.com/newsroom-detail/lilium-architecture-design-principles">
 Lilium
 </ExternalLink>
 
 }
 width="750"
 height="391"
 positionCenter={true}
/>

So when can we expect to take our first flight in an eVTOL? “That’s a difficult question!” smiles David. “It will ultimately depend on the first real flight tests of the final configurations as only then will we have a clear view on any problems that need to be addressed before certification. What I can say is that there is at least one OEM targeting the Paris Olympic games. After that, eVTOLs will still be in limited operation as there is still a lot of work to be done on the certification side. But I expect that the eVTOL industry will continue to progress from 2024 onwards.”

---

### Interesting links:

- <ExternalLink href="https://aviationweek.com/air-transport/faa-releases-first-evtol-certification-basis-comment">FAA Releases First eVTOL Certification Basis For Comment</ExternalLink>

- <ExternalLink href="https://verticalmag.com/news/airshaper-takes-fresh-approach-to-complex-field-of-computational-fluid-dynamics/">AirShaper takes fresh approach to complex field of computational fluid dynamics</ExternalLink>

- <ExternalLink href="https://www.easa.europa.eu/en/light/topics/vertical-take-and-landing-vtol">Vertical Take-off and Landing (VTOL)</ExternalLink>

- <Link href="/blog/airspeeder">Airspeeder - The Electric Flying Car Racing Series</Link>

---

eVTOL certification interview with EASA

How does aerodynamics affect speed?

Drones are everywhere these days. As with many technologies, the advancements made in energy storage with lithium-ion batteries has been a game changer. The drone industry is estimated to be worth $43 billion in 2025. They are no longer toys for hobbyists, but serious pieces of hardware used throughout the world and have even flown on <ExternalLink href="https://mars.nasa.gov/news/8923/nasas-ingenuity-mars-helicopter-succeeds-in-historic-first-flight/">Mars!</ExternalLink>

<ImageWithCaption
 src="/assets/images/quadcopter-drone.jpeg"
 alt="Quadcopter drones are used for everything from filming movies to supporting search and rescue operations. CREDIT: www.london-fire.gov.uk"
 caption={
 
 Quadcopter drones are used for everything from filming movies to
 supporting search and rescue operations. CREDIT:{' '}
 <ExternalLink href="http://www.london-fire.gov.uk">
 www.london-fire.gov.uk
 </ExternalLink>
 
 }
 width="700"
 height="341"
 positionCenter={true}
/>

---

## Quadcopters

The first type of drone that comes to mind are quadcopters, which use multiple rotors to provide lift and propulsion. These are small and easy to use and therefore perfect to replace helicopters in a range of tasks where hovering is a key element.

<ImageWithCaption
 src="/assets/images/drone-thermal-camera.jpg"
 alt="Emergency services use drones equipped with infra-red cameras to capture thermal images. CREDIT: www.dronedj.com"
 width="700"
 height="350"
 positionCenter={true}
/>

However, as the applications for drones has increased in areas such as agriculture, mining, defence, mapping and surveying, the range and flight time of quadcopters makes them less ideal for these types of tasks. For example, if you want to map a vast area of agricultural land using advances in drone automation, battery life becomes a major issue. A quick look at a typical manufacturer’s website shows that flying time and range are among the first things that need to be considered.

<ImageWithCaption
 src="/assets/images/drone-field-survey.jpeg"
 alt="Field surveys for agriculture can be automated with drone technology. CREDIT: www.pix4d.com"
 width="700"
 height="394"
 positionCenter={true}
/>

---

## Fixed wing VTOL drones

This has given rise to fixed wing VTOL drones. These are hybrid aircraft with lift producing bodies and wings that also have the ability to hover using rotors. Once airborne, the wings are able to support the drone and the only power requirement is for horizontal motion. This is especially important for drones with heavy camera payloads which are very energy hungry. They also give operational benefits where there isn’t space to land a standard winged drone.

<ImageWithCaption
 src="/assets/images/vtol-drone-example.jpeg"
 alt="VTOL drones combine wings and vertical rotors for short and vertical take-offs. CREDIT: www.deltaquad.com"
 width="700"
 height="266"
 positionCenter={true}
/>

---

## Optimizing fixed wing VTOL drones

The combination of aerodynamics and rotor dynamics makes a fixed wing VTOL drone a more complicated vehicle to design than a quadcopter. From a purely aerodynamic perspective, the basic design of the body can be taken as a standard 3D modelling and CFD problem. AirShaper has a number of tools to make this design process as simple as possible.

We have created a video which explains some of the <Link href="/videos/airfoil-design-for-a-drone/kAXN3MlQxxc">design considerations for drone airfoils</Link> and another video which shows a <Link href="/videos/drone-design-2-3d-flow-analysis/FZHYcqRcDJM">3D flow analysis of blended bodies</Link> using AirShaper. The capability of our software was fully tested during our project with <ExternalLink href="https://www.neuralconcept.com/post/sensefly-airshaper-and-neural-concept-designing-the-ultimate-drone">Sensefly and Neural Concept</ExternalLink>. Using our cloud simulation capabilities as their CFD engine, they optimised the design of a blended wing drone.

- <Link href="/research/deep-learning-automated-drone-design">
 Check out our technical paper on using Neural Networks to optimize a
 fixed-wing drone
 </Link>

<ImageWithCaption
 src="/assets/images/blended-body-drone-optimization_2.png"
 alt="The blended body of the original design (left) was optimized (right) using AirShaper and neural networks to increase overall lift"
 width="800"
 height="298"
 positionCenter={true}
/>

---

## Propulsion is important to all aircraft

Once there is an optimized basic vehicle that meets the various design requirements, the next stage is to integrate the power source. That requires aerodynamic design input in two areas: the propeller itself and the way it interacts with the rest of the design.

In isolation, propeller designs are a complicated field of aerodynamic study in their own right. Studies of propeller thrust and efficiency have been carried out from the original Wright Flyer to the current day. Drones share many similarities with full size aircraft and so their propulsion systems have been researched for a surprisingly long time.

---

## Integrating propellers into aircraft design

Putting the intricacies of rotor design aside, adding one or more to an aircraft design can be seen as a problem. The complex flows can dramatically affect an otherwise well-designed shape. This doesn’t have to be the case with careful design and modern CFD.

In the world of full-size aircraft, <Link href="/videos/electric-aviation-nasa-interview-on-maxwell-x57-part-2-propeller-design/UDZBqDQGU8o">NASA’s X-57 Maxwell aircraft</Link> studies have shown how electric propulsion can be used to revolutionise wing design. We covered this in a series of videos where we interviewed NASA engineers and discussed that there is minimal difference between a drone and a full-size aircraft.

“They are all going to have to deal with some of these trade-offs,' highlights Nick Borer, Performance and sizing lead at Armstrong and Langley. "How does the flow interact with the wing, are you using it for efficient thrust production or are you using it to efficiently generate lift in edgewise flight?”. These are just some of the challenges that face drone designers when integrating propellers.

- <ExternalLink href="https://ntrs.nasa.gov/api/citations/20170005883/downloads/20170005883.pdf">
 Find out more about the NASA X-57 high lift wing propeller system{' '}
 </ExternalLink>

---

## Adding rotating elements to an AirShaper CFD project

To understand all the airflow interactions caused by the propellers, modelling the effect of the propellers and rotating elements in CFD is essential. We have recently introduced this to the AirShaper platform and explain how it works in this <Link href="/videos/how-to-model-rotating-elements-in-cfd-computational-fluid-dynamics-using-mrf-ami-and-more/zFSXtRGk_H8">rotating elements video</Link>.

<ImageWithCaption
 src="/assets/images/airshaper-propeller-cfd.png"
 alt="Drone rotor simulation in AirShaper allows the use of multiple propellers"
 width="700"
 height="343"
 positionCenter={true}
/>

Simulations can now be run with and without a rotor implementation to establish the effects on the design. For a VTOL drone design, it may also be important to look at the effect of rotating and non-rotating propellers to ensure flight characteristics remain unchanged if they are not in use. Drones have come a long way in the last 10 years and we look forward to continuing developing the capabilities of AirShaper to help simulate these fascinating types of aircraft!

---

##### Interesting links:

 

<ExternalLink href="https://airshaper.com/cases/sense-fly-increasing-drone-flight-time">
 Increasing flight time of drones
</ExternalLink>

 

<ExternalLink href="https://airshaper.com/videos/how-to-model-rotating-elements-in-cfd-computational-fluid-dynamics-using-mrf-ami-and-more/zFSXtRGk_H8">
 Learn more about modelling rotating elements in CFD using MRF, AMI and more
</ExternalLink>

---

How CFD can optimize VTOL drone design

The Audi TT concept was first unveiled at the 1995 Frankfurt Motor Show. This two door coupe featured four wheel drive and was powered by a 1.8 litre inline four cylinder turbocharged engine. The clean lines of the <ExternalLink href="https://www.tate.org.uk/art/art-terms/b/bauhaus">Bauhaus-inspired styling</ExternalLink> wowed the Frankfurt audience and the wider media and was deemed a revelation for the previously conservative Audi brand.

The production car sold well initially, but some high-profile incidents in Germany made it clear that the car had some problems with high-speed stability. Audi had to solve these issues fast and developed a new version which incorporated a small rear spoiler and revised suspension settings.

<ImageWithCaption
 src="/assets/images/audi-tt-spoiler-side.jpeg"
 alt="Audi TT rear spoiler side view"
 caption={
 
 The comparatively small rear spoiler was rejected by stylists initially
 but made a huge difference to the high-speed handling of the revised car.
 CREDIT:{' '}
 <ExternalLink href="https://www.caranddriver.com/reviews/a15140613/we-take-audis-tamed-tt-for-a-spin-first-drive-review/">
 Car And Driver
 </ExternalLink>
 
 }
 width="700"
 height="283"
 positionCenter={true}
/>

---

## Modelling the Audi TT in CFD

The changes Audi made to the TT were a success and the car has now become something of a classic. But how much difference did that rear spoiler actually make to the aerodynamics and overall performance of the Audi TT? To find out, we decided to use AirShaper software to conduct an aerodynamic study which compared the original version of the Audi TT without the spoiler against a revised version with the spoiler.

This was fairly easy to do: we purchased a public 3D model of the Audi TT with a spoiler, and then created a copy without spoiler. Further detail could be added by automatically incorporating a rotating wheel simulation. This identifies the wheels from the base geometry and is a valuable tool when investigating automotive aerodynamics.

- <Link href="/videos/how-to-model-rotating-elements-in-cfd-computational-fluid-dynamics-using-mrf-ami-and-more/zFSXtRGk_H8">
 Learn more about modelling rotating elements in CFD using MRF, AMI and more
 </Link>

---

## CFD results

AirShaper allows simulations to run in the cloud and produces a number of different ways to visualise the results, all of which are detailed in an automatically generated PDF report. However, one of the simplest methods to compare results is to look at key numbers. The drag and lift coefficients for both the front and rear are shown in the table below.

| | Without spoiler | With spoiler |
| --------------------------------------- | --------------- | ------------ |
| Drag Coefficient, Cd | 0.305 | 0.265 |
| Total Lift Coefficient, Cl | 0.098 | -0.018 |
| Front Lift Coefficient, Cl,f | -0.063 | -0.072 |
| Rear Lift Coefficient, Cl,r | 0.161 | 0.053 |

As this is a public 3D model, don't focus on the absolute numbers, but rather on the relative differences. The most important change for the Audi TT is the reduction in rear lift coefficient from 0.161 to 0.053. This clearly indicates how a small feature like a spoiler can have a strong impact on the rear lift of the car.

---

## Correlating results with reality

Fortunately for us, after the Audi TT had been revised, the changes were covered in various automotive magazines. <ExternalLink href="https://www.caranddriver.com/reviews/a15140613/we-take-audis-tamed-tt-for-a-spin-first-drive-review/">Car And Driver</ExternalLink> in the US conducted a correlation study between the original Audi TT, the revised version with the spoiler and several competitors at 125mph. The rear lift values of this study are detailed in the table below.

| | Original TT | Revised TT | BMW Z3 | Mercedes SLK | Porsche Boxster |
| --------------- | ----------- | ---------- | ------ | ------------ | --------------- |
| Rear Lift (Ibf) | 148 | 53 | 64 | 104 | 68 |

Although absolute values cannot be compared (due to the lack of detail on the 3D model), both simulation and test feature a comparable 65% drop in lift.

---

## Visualising the results

The power of CFD is that it gives detailed visualisations of the results. For example, surface pressure and surface friction can be displayed as coloured maps, while velocity streamlines show how the air behaves as it flows over a vehicle. These visualisations help us to really understand the interactions between airflows and the differences between the two configurations with and without a spoiler.

---

## Streamlines

<ImageWithCaption
 src="/assets/images/audi-tt-spoiler-comparison-top-view.png"
 alt="CFD streamlines of the wake with and without the spoiler on the Audi TT"
 caption={
 
 Streamlines show the wake with the spoiler (top) vs the wake without the
 spoiler (bottom) in{' '}
 <ExternalLink href="https://airshaper.com/">AirShaper</ExternalLink>
 
 }
 width="800"
 height="596"
 positionCenter={true}
/>

In its original form, the Audi TT acted similar to an aircraft wing. The flow over the top surface has to speed up to meet the under-car flow at the rear of the car. As Bernoulli’s equation sets out, this higher velocity means the static pressure is lower above the car than below, otherwise known as lift. The air follows the body shape all the way to the rear bumper, creating a strong downwash to the wake.

The spoiler works by disrupting this flow and slowing it down. A pocket of recirculating air is created ahead of the spoiler. This slow-moving air means a higher static pressure, eliminating the lift. The flow also separates from the rear window much earlier, creating a recirculation behind the car and a much larger wake that no longer downwashes.

<ImageWithCaption
 src="/assets/images/audi-tt-spoiler-comparison-side-view.png"
 alt="Streamlines showing that with the spoiler the flow seperates earlier creating a large wake. Without the spoiler, the flow remains attached and creates a strong downwash"
 caption={
 
 The results from{' '}
 <ExternalLink href="https://airshaper.com/">AirShaper</ExternalLink> show
 that with the spoiler (top) the flow seperates much earlier creating a
 large wake. Without the spoiler (bottom) the flow follows the shape of the
 rear bumper and creates a strong downwash
 
 }
 width="800"
 height="374"
 positionCenter={true}
/>

---

## Pressure maps

The effect of this is illustrated in the pressure maps shown below. The increased pressure on the spoiler affects the surrounding areas of the car as well. Hot colours show where pressure rises on the rear window, the top of the boot and even on the areas downstream of the spoiler. Lift is decreased by the higher pressures on horizontal surfaces and drag reduced by the increases on rearward-facing areas of the car.

<ImageWithCaption
 src="/assets/images/audi-tt-spoiler-comparison-pressure-3d-view-2.png"
 alt="Two pressure maps showing that the spoiler increases the surface pressure on the rear window and boot compared to without the spoiler"
 caption={
 
 Comparing the two pressure maps in{' '}
 <ExternalLink href="https://airshaper.com/">AirShaper</ExternalLink>, we
 can see that the spoiler (right) increases the surface pressure on the
 rear window and boot compared to the original version without the spoiler
 (left)
 
 }
 width="600"
 height="341"
 positionCenter={true}
/>

---

## A simple solution to a big problem

The Audi TT demonstrates how a big problem can be solved with a relatively small solution. The spoiler added here is not a rear wing element generating downforce in its own right. It is simply a trip to interrupt the airflow, which changes the aerodynamic behaviour of the whole car. Audi made changes to the rear suspension too, but it is likely that the spoiler had the most significant effect on improving high-speed handling.

It is interesting to see how a problem like this caught out a large automotive company like Audi in 1998. Now, modern computing power and tools like AirShaper allow us to carry out analysis like this from a home PC.

---

##### Interesting links:

 

- <ExternalLink href="https://www.tate.org.uk/art/art-terms/b/bauhaus">
 Learn about some design history whilst studying aerodynamics
 </ExternalLink>

 

- <ExternalLink href="https://www.caranddriver.com/reviews/a15140613/we-take-audis-tamed-tt-for-a-spin-first-drive-review/">
 Read the Car And Driver road test review of the revised Audi TT
 </ExternalLink>

---

A CFD analysis of the Audi TT spoiler

Few road cars are capable of achieving top speeds above 250mph (402kph) - the realm of the hypercar. Cars like the multi-million-dollar Bugatti Chiron Super Sport 300+ or the McLaren Speedtail are a couple of examples. But what if you had a supercar and wanted to achieve this hypercar level of performance?

This was the goal of <ExternalLink href="https://7x.design/gallery-1">7X Design</ExternalLink>, who converted a Lamborghini Huracan from a 600bhp, 200mph (320kph) production supercar into a 2000bhp, 300mph (480kph) coach-built Lamborghini Rayo hypercar.

---

## 21st century coachbuilding

Coachbuilding is the engineering art of taking a base vehicle chassis and making it into something unique. In the 1920s, companies like HJ Mulliner created one-off Rolls Royce bodies for their customers. More recently, Pininfarina developed the Ferrari Enzo-based P4/5, also known as the 'Glickenhaus', which generated more downforce and less drag than the original Enzo. This year, 7X Design took a Lamborghini Huracan and created the Lamborghini Rayo, which featured a bespoke carbon fibre body as well as extreme engine tuning.

---

## The Lamborghini Rayo brief

The project was instigated by David Gomez, founder of 7X Design and the owner of a tuned Huracan. He approached <ExternalLink href="https://www.adrianoraeli.com/7x-rayo">Adriano Raeli Design</ExternalLink> to see what was possible. 'The brief was pretty straightforward,' reveals Adriano Raeli, Design Specialist at Adriano Raeli Design. 'We had to re-engineer the aerodynamics of a car with around triple its original horsepower to create a matching aero body that would allow it to achieve its best top speed.'

'There were some practical limitations as we wanted to maintain the original road-going capabilities of the car,' continues Raeli. 'For example, the McLaren Speedtail is a special vehicle with an elegant shape, but it is compromised on the road in terms of ramp angles and overall length. We wanted to avoid this. We also couldn't change the roof and wide windshield because they were part of the structure. The A-pillar in particular generated problematic drag-inducing vortices.'

<ImageWithCaption
 src="/assets/images/7x-design-lamborghini-rayo-rear.jpeg"
 alt="The starting point: a 1,900bhp twin-turbo modified Lamborghini Huracan. CREDIT: www.undergroundracing.com"
 width="700"
 height="390"
 positionCenter={true}
/>

---

## Inspiration to reality

Automotive styling is a unique mixture of engineering and design. The most elegant of lines often create unworkable aerodynamics. Despite the different aerodynamic requirements and <Link href="/videos/the-relation-between-turbulence-reynolds-and-wind-tunnel-testing/sV8l8xd4MEQ">Reynolds numbers</Link>, the project was specifically inspired by figher aircraft.

<ImageWithCaption
 src="/assets/images/f35-fighter-jet.jpg"
 alt="Fighter aircraft provide some of the inspiration for Adriano Raeli's high performance automoitve projects. CREDIT: www.lockheedmartin.com"
 width="800"
 height="294"
 positionCenter={true}
/>

'They are one of the fastest and highly technological vehicles on the planet, short of spacecraft,' observes Raeli. 'When David saw the initial sketch he said, 'this is it!' That was the starting point of the design process. We then went from those quick couple of lines to a 3D model and then evolved the aerodynamic design of that model in simulation.'

<ImageWithCaption
 src="/assets/images/7x-design-lamborghini-rayo-initial-sketch.png"
 alt="The elegant original napkin sketch required engineering input to turn into a workable package. CREDIT: www.adrianoraeli.com"
 width="800"
 height="209"
 positionCenter={true}
/>

---

## CFD simulation with AirShaper

There were three aerodynamic aims for the CFD programme:

1. Reduce the drag to allow the car to achieve the 300mph (480kph) target

2. Create balanced downforce to ensure the car remains stable at speed

3. Limit the total amount of downforce so the car doesn't get squashed at high speeds

To help achieve this, Raeli experimented with the design of the rear wing and in the end replaced it with two winglets. 'For some projects, a rear wing is a must, there's no other way to achieve that kind of downforce without a wing,' explains Raeli. 'To reduce drag, we opted for winglets instead, which are located in cleaner air. So I designed a general aerofoil profile and tested it in CFD. There was no specific math behind it initially, just general design and aerodynamic principles. AirShaper’s morphing tool was instrumental to evolving the design and it's helped us achieve better speeds and downforce without a rear wing.'

<ImageWithCaption
 src="/assets/images/7x-design-lamborghini-rayo-rear-winglets.png"
 alt="Rear winglets replace the full width spoiler and are key aerodynamic elements of the design. CREDIT: www.adrianoraeli.com"
 width="800"
 height="302"
 positionCenter={true}
/>

AirShaper's aerodynamic shape optimization tool also helped with the design of the underbody and the rear diffuser, which are essential as they generate significant downforce with minimal drag. The software showed that instead of a fairly square cross section, a more rounded and larger central tunnel with smaller side tunnels performed better.

A lot of effort went into the front splitter, to optimize the way the air is accelerated underneath the car. Additionally, large air curtains were added to shield the front wheels and reduce their drag. Other areas of improvement included the height and length of the tail, the rear window cover, side air intakes, front wheel well ventilation and more.

---

## The benefits of CFD

AirShaper is not just designed for aerodynamicists, but also designers as well. The intuitive and easy to use software allows designers to make CFD a key element in their design process. 'You are able to test your design changes and see how they affect the aerodynamic performance of the car,' highlights Raeli. 'If we test a specific detail or a volume change in the nose for example, within a few simulations we can understand how it is affected, positively or negatively. We can then adjust the design for the next round of optimizations whilst keeping in mind the proportions we wanted to maintain.'

---

## The results

Through the rounds of development, the drag coefficient was reduced by 28.5% to a Cd of just 0.279 whilst doubling the downforce (thanks to the optimized underfloor aerodynamics and top winglets).

<ImageWithCaption
 src="/assets/images/7x-design-lamborghini-rayo-pressure-clouds.png"
 alt="The pressure clouds of the final design show a signifcant drag reduction which is vital for the top speed attempt"
 width="800"
 height="315"
 positionCenter={true}
/>

The car was taken to the <ExternalLink href="https://www.applusidiada.com/global/en/what-we-do/services/spain-proving-ground">IDIADA test track</ExternalLink> in Spain for initial testing of the new body, rendered in carbon fibre. The results were better than the team had hoped for, despite the limitations on the available straights. The car achieved 278mph (447kph) with more to come from further powertrain and aerodynamic development. Later this year, the car will be taken to a more suitable location to try to reach the 300mph (480kph) target.

<ImageWithCaption
 src="/assets/images/7x-design-lamborghini-rayo-testing-2.png"
 alt="The finished car was tested at the banked turns and long straights of IDIADA's proving ground. CREDIT: img1.wsimg.com"
 width="800"
 height="448"
 positionCenter={true}
/>

'What we have here is a great achievement because, if you think about it, how many companies attempt something like this?' questions Raeli. 'They usually have to invest millions of dollars in R&D and a lot of time. Whereas our small team, together with AirShaper's expertise and the knowledge of the people who built the car, allowed us to upgrade the Lamborghini Huracan to achieve those ambitious speeds. I think that's a pretty big accomplishment.'

---

##### Interesting links:

 

<ExternalLink href="https://www.instagram.com/7xdesign/">
 Check out 7x Design's Instagram
</ExternalLink>

 

<ExternalLink href="https://www.applusidiada.com/global/en/what-we-do/services/spain-proving-ground">
 The IDIADA proving ground
</ExternalLink>

From supercar to hypercar - the Lamborghini Rayo

The world is very lucky to have NASA, a publicly funded body with a requirement to openly share all of its research. As we discovered in our <Link href="/blog/best-aerodynamic-resources">guide to the best aerodynamic resources</Link>, the NASA report database is a goldmine of freely available data for aerodynamicists and engineers. It also contains a huge archive of photographs and publications chronicling their history.

That’s where we came across <ExternalLink href="https://ntrs.nasa.gov/citations/20205009237">'The World’s Largest Wind Tunnels'</ExternalLink> book by Kenneth W. Mort. This publication covers the history of the 40 x 80ft closed loop and 80 x 120ft open loop tunnels at NASA Ames in California, known as the National Full Scale Aerodynamics Complex (NFAC). It provides the perfect starting point to delve into the world of full size wind tunnel testing.

<YouTubeEmbed
 videoId="m4rysu8LlLM"
 title="Electric Aviation - NASA interview on Maxwell X57"
/>

---

## Why full size?

A lot of wind tunnel testing is done at model scale for obvious reasons. The test facility can be much smaller, fans less powerful and it is much easier to produce models and test parts. If you want to take an Airbus A380 and put it into a wind tunnel, its 80m wingspan is only the start of the problems that need to be solved.

If that is the case, why do engineers and aerodynamicists still want to try to test in very large wind tunnels? NASA’s 80 x 120ft tunnel (roughly 24m by 36m) will take an actual example of full size fighter aircraft. The key word here is actual.

<ImageWithCaption
 src="/assets/images/fighter-jet-wind-tunnel-testing.jpeg"
 alt="An F/A-18 Hornet fighter jet undergoing high angle of attack testing in a wind tunnel. CREDIT: www.nasa.gov"
 width="600"
 height="579"
 positionCenter={true}
/>

The main reason for wanting to investigate a production aircraft is to establish its real-world performance. A typical problem when using wind tunnel models is that they can be too good a representation of the vehicle. For example, on a real aircraft, rivet heads, panel gaps, antenna and actuators all create drag and prevent aerodynamic surfaces working in the same way that they would do on a scale model. This is particularly vital for low-speed scenarios like take-off and landing where lift is at a premium.

The same applies for ground vehicles. A scale model Formula 1 car is very clean and stiff, so wind tunnel measurements are very accurate. A real Formula 1 car though, has gaps in the bodywork and lightweight carbon structures that deflect, giving quite different results on some occasions. Investigating these details led Williams, Toyota and Sauber to build their own full size wind tunnels in the early 2000s, which are unfortunately now banned by the regulations.

- <ExternalLink href="http://www.icas.org/ICAS_ARCHIVE/ICAS2002/PAPERS/3103.PDF">
 Check out this paper which summarises a wind tunnel test of the Dash 8 Q400
 airliner in the NASA tunnel
 </ExternalLink>

---

## Tunnel interactions

As we saw in our <Link href="/videos/scale-model-wind-tunnel-testing/qqYiz1eo-F4">scale model wind tunnel testing video</Link>, a large wind tunnel section also helps achieve more accurate results with scale model testing. Keeping the section large with a small model allows you to minimise blockage effects and interactions with the floors and walls. A lot of work carried out in the NASA tunnels centres around low speed/high angles of attack scenarios and rotorcraft where there are high downwashing effects which are very sensitive to these things.

A large air volume and working section is particularly useful for quite bluff bodies that displace a lot of air. This was demonstrated in the NASA wind tunnel during a <ExternalLink href="https://www.llnl.gov/news/lawrence-livermore-national-lab-navistar-work-increase-semi-truck-fuel-efficiency-full-scale">fuel efficiency test of a road going truck and trailer rig</ExternalLink>. The NASA 120 x 80ft tunnel is actually very well suited for this type of testing because it can only achieve 100mph in its large configuration.

<ImageWithCaption
 src="/assets/images/truck-fuel-efficiency-test.jpeg"
 alt="A full semi-trailer under test in the 80 x 120ft section of the NASA wind tunnel. CREDIT www.llnl.gov"
 width="700"
 height="483"
 positionCenter={true}
/>

These tests are desirable to help bridge the gap between CFD and the real world. CFD can model a vehicle without the constraints of a working section, but correlating the results is often difficult. Testing a truck on the road is too uncontrolled and instrumentation limited to do this effectively.

- <Link href="/videos/cutting-truck-bus-emissions-the-vecto-airdrag-tool/s2QyP6n4Zxs">
 Find out how to apply the Vecto Air Drag tool to truck and bus aerodynamics
 </Link>

---

## Large scale engineering and lots of power

NASA’s 80 x 120ft tunnel is the largest in the world and is an engineering marvel in its own right. The basis for the building complex was a closed loop 40 x 80ft tunnel conceived in the 1940s. It was converted to add the 80 x 120ft open loop section in the 1980s, powered by the same fans.

<ImageWithCaption
 src="/assets/images/external-view-of-nfac.jpg"
 alt="An aerial view of the complete NFAC. CREDIT: www.nasa.gov"
 width="700"
 height="516"
 positionCenter={true}
/>

The six fans are 40ft in diameter and each is rated at 22,500hp which generate 115mph flow in the 80 x 120ft tunnel and 345mph in the 40 x 80ft closed loop.

<ImageWithCaption
 src="/assets/images/main-nfac-fans.jpeg"
 alt="The bank of fans powering the NFAC. CREDIT: www.nasa.gov"
 width="700"
 height="560"
 positionCenter={true}
/>

Whilst the headline working section numbers for the NASA tunnels are large, the nature of a wind tunnel means that other aspects of the air circuit are much larger. Upstream of the 40 x 80ft section, before the contraction, the tunnel is 132 x 173ft (40 x 52m).

<ImageWithCaption
 src="/assets/images/1947-nasa-wind-tunnel-working-section.jpeg"
 alt="View of the 40 x 80ft working section from 1947. CREDIT: www.nasa.gov"
 width="700"
 height="467"
 positionCenter={true}
/>

The engineering challenges don’t stop once the wind tunnel itself has been built. Such large test items each come with their own logistical problems during installation and removal. The tunnel working section has a hinged roof to allow access.

All-in-all, the facility is as much a wonder of engineering as the different vehicles that have been tested in it over the last eighty years.

<YouTubeEmbed
 videoId="4PabZAx-4Yw"
 title="Testing a Boeing aircraft tail in the world's largest wind tunnel"
/>

---

##### Interesting links:

 

<ExternalLink href="https://airshaper.com/videos/wind-tunnel-test-section/L1AYo9Mk1EI">
 The wind tunnel test section explained
</ExternalLink>

The largest full size wind tunnel in the world - NASA

## Introduction

We are designing a versatile all-electric amphibious aircraft to transport people and goods. The amphibious aircraft concept we are developing is a flying boat type and it uses a hull-based fuselage to meet the hydrodynamic requirements for the aircraft to take-off and land on the water bodies. Operation from land airports is achieved through the retractable landing gear system onboard the aircraft.

<YouTubeEmbed
 videoId="ZPjjg4_UDlA"
 imgSize="hqdefault"
 title="1/5th scale model testing"
/>

We want people to travel emission-free from city centre to city centre at a fraction of the time. Small and flexible sea terminals will facilitate the onboarding and offboarding of our passengers, which is especially useful in mountainous areas along the coast.

## Efficiency is key for electric aviation

For electric aviation to be technically & economically viable, improving efficiency is key, especially when it comes ot aerodynamics. A low drag coefficient and a higher lift-to-drag ratio have a direct impact on the aircraft performance and eventually on the range and endurance of the plane. Some of the ways we have tried to achieve this include:

- the use of natural laminar flow airfoils
- optimised high lift devices
- a streamlined hull design without compromising on the hydrodynamic requirements
- the use of a push-pull electric propulsion setup to further reduce drag.

Overall, we are currently involved in multidisciplinary optimisations and expect to freeze the design in a year from now.

## Hydrodynamics

Hydrodynamic design is crucial for amphibious operations. For the past 12 months, we have been conducting intense hydrodynamic testing of various hull designs for the plane. In order to evaluate the hull designs for the plane in terms of stability and hydrodynamic resistance, we have performed multiple open water tests and also testing in a towing tank in collaboration with SINTEF Norway.

<YouTubeEmbed
 videoId="Et8UBTX7xDo"
 imgSize="hqdefault"
 title="Byfly Towing Tank test at Sintef Norway (video credit: El-Fly)"
/>

How simulations have helped, which parameters are important (lift and drag, roll pitch yaw) Which insights you had, which improvements you'll make based on the results.

## Analysis & optimization through simulations

With the online CFD simulation platform AirShaper, we were able to verify the feasibility of particular flight conditions. Getting the angle of attack of the wing right is crucial towards for economical cruise conditions. Using the lift & drag values from the simulations, for different angles of attack, allows us to optimize further for efficiency. Furthermore, by analysing surface pressure & surface friction, 3D streamlines, flow structures in the wake and other simulation results, we’re able to spot areas for further improvements to the aerodynamics of the plane.

<YouTubeEmbed videoId="62QS4M6M_9Q" title="Full scale model CFD in AirShaper" />

## Experimental testing

We are currently in the R&D phase involving experimental testing. Our goal is to first launch the commercial service in Norway by 2030, where it is highly suitable for the challenging terrain. We will operate from city centre to city centre, and then expand operations to other parts of the world.

Interesting links:

<ExternalLink href="https://el-fly.no/">El-Fly</ExternalLink>

Electric Aviation - The Byfly Seaplane

Tim Barber runs a prep shop and race team, <ExternalLink href="http://www.tfbperformance.com/go-racing/">TFB Performance</ExternalLink>, out of Sonoma Raceway in California. TFB Performance provides vehicle preparation, track support and driver coaching to its customers who race in Trans-Am, endurance prototypes, Spec Miata, SRO World Challenge and many more.

Customers who run racecars with aerodynamic packages typically rely on Tim’s team to optimise aero performance. The convenience and affordability of <ExternalLink href="https://www.rapidscan3d.com/software/polyworks/modeler">RapidScan</ExternalLink> and <Link href="/videos/how-to-run-an-aerodynamic-simulation/O_DNDxCtI_I">AirShaper</Link> allowed Tim to not only access aero data, but analyse the effect of set-up changes quickly and accurately, without investing in wind tunnels or complicated CFD software. Making aerodynamics accessible to a much broader range of racer than ever before.

---

## Establishing an aeromap

The amount of downforce of a racecar varies significantly with ride height and rake. So it is vital to fully understand this relationship if you want to have any chance of establishing an effective set-up over the weekend.

The best way to achieve this is to create an <Link href="/videos/how-aero-maps-can-improve-race-car-performance/u-GyTRblNmc">aeromap</Link>. This maps aerodynamic properties such as downforce and drag as a function of car set-up such as ride height and rake. These plots help to understand the sensitivities between aero coefficients and car set-up, which is an important tool to utilise to adjust the car.

- <Link href="/videos/how-aero-maps-can-improve-race-car-performance/u-GyTRblNmc">
 How aero maps can improve racecar performance
 </Link>

<ImageWithCaption
 src="/assets/images/trans-am-ta2-mustang-surface-pressure.png"
 alt="Surface pressure plot of a Trans-Am TA2 Mustang"
 width="800"
 height="469"
 positionCenter={true}
/>

OEM’s obtain these sensitivities through wind tunnel testing, but this is far too expensive for most small teams and typically requires aerodynamic specialists. Furthermore, the rules in most race categories prevent the use of wind tunnels.

Track testing is the next best option. However, varying weather and track conditions along with other cars on track, make it difficult to run representative comparison tests. Track testing also requires a lot of time from the drivers and as most of our clients have full-time jobs, this is simply not possible.

Consequently, our small team cannot afford the luxury of aerodynamic data, but our customers still rely on our expertise to optimise the aero performance of their cars. Typically, this means spending a lot of time analysing onboard data and combining it with driver feedback. However, the short race weekend formats and lack of testing makes it incredibly difficult to gain an accurate picture of how set-up changes affect the aerodynamics.

To help solve this problem, we decided to partner with RapidScan and AirShaper for our Trans-Am TA2 program. This is a road race stock car that has simple aero adjustments available. However, getting the set-up right is essential as qualifying and the 100-mile race are run on the same set of tires. So an unbalanced car will unnecessarily wear the tires that already degrade heavily throughout the race.

<ImageWithCaption
 src="/assets/images/trans-am-ta2-mustang.jpg"
 alt="Trans-Am TA2 Mustang"
 width="700"
 height="444"
 positionCenter={true}
/>

---

## 3D scanning

The first stage was to create a 3D model that could be imported into AirShaper, which involved 3D scanning one of our TA2 cars. This required no preparation from our side, and within a day Richard Feijoo, 3D solutions specialist from RapidScan, scanned the entire car from top to bottom. This scan was then converted into a 3D surface model, ready for simulating in AirShaper.

<ImageWithCaption
 src="/assets/images/raw-3d-scan-ta2-mustang.png"
 alt="The raw 3D scan of the Trans-Am TA2 Mustang"
 width="700"
 height="383"
 positionCenter={true}
/>

---

## Simulating in AirShaper

Within minutes, I had imported the 3D model into AirShaper and adjusted the set-up parameters of the simulation. I modelled a range of different car configurations with two main objectives. One was to understand how much ride height affected straight line drag, and the other was to quantify how much rake affected downforce.

Being able to quantify the aerodynamic performance from a given ride height or wing change is invaluable. This was the first time that we were able to achieve this with reliable data rather than using educated guesses. The results from AirShaper also benefitted our drivers, as we could explain what to expect instead of them having to rely on feeling the changes themselves.

<ImageWithCaption
 src="/assets/images/trans-am-ta2-increased-rake.png"
 alt="Velocity slice illustrating the aerodynamic effect of increased rake on the Trans-Am TA2 racecar"
 width="700"
 height="543"
 positionCenter={true}
/>

To understand the results in more detail, I was able to connect with AirShaper online where a specialist walked me through the data and the various models they created for our car. The PDF report provided, was also really useful. It presented the results in an understandable way and included a wide variety of colour maps illustrating surface pressure, surface friction, velocity streamlines, pressure clouds and even noise analysis. Within a few simulations we had quantitive values of the aero effect of set-up changes, without the need for wind tunnel or track tests.

---

## Beyond lap time

Drivers and teams typically prioritize speed and lap time first, but the AirShaper data can also be used to improve cooling and reliability. For example, in Trans-Am TA2, there are a number of different options for radiator and brake duct openings. By using the simulation results, we were able to adjust these openings to the optimum position that allowed enough air flow for cooling, whilst maintaining maximum downforce and minimising drag.

Furthermore, the regulations specify that the overall surface of our TA2 car has to meet body templates, but we are allowed to design and manufacture our own airbox and ducting. Again, using the data from RapidScan and AirShaper we simplified our build process and can now quantitatively say that we have the best aerodynamic option available. I'm looking forward to running some more cars through this process so that we can optimise the aerodynamic performance of those too!

<ImageWithCaption
 src="/assets/images/trans-am-ta2-isosurfaces-2.png"
 alt="3D pressure surfaces on the Trans-Am TA2 reference model"
 width="700"
 height="213"
 positionCenter={true}
/>

---

##### Interesting links:

 

<ExternalLink href="https://www.racecar-engineering.com/tech-explained/what-is-an-aero-map/">
 What is an aeromap?
</ExternalLink>

 

<ExternalLink href="https://www.rapidscan3d.com">RapidScan</ExternalLink>

AirShaper BlogPassion for aerodynamics

eVTOL certification interview with EASA

Wouter Remmerie

How does aerodynamics affect speed?

Geoff Dymott

How CFD can optimize VTOL drone design

Wouter Remmerie

A CFD analysis of the Audi TT spoiler

Geoff Dymott

From supercar to hypercar - the Lamborghini Rayo

Geoff Dymott

The largest full size wind tunnel in the world - NASA

Geoff Dymott

Electric Aviation - The Byfly Seaplane

Sathvik Sathyanarayana Rao

Helping teams understand the aero of a Trans-Am TA2 Mustang

Tim Barber

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