Is Ducati’s Aerodynamic Swingarm MotoGP Legal? Factories Protest

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Andrea Dovizioso’s victory in the opening race of the 2019 MotoGP season at Qatar is currently subject to appeal. Dovizioso raced in Qatar using the aerodynamic components previously debuted by factory Ducati teammate Danilo Petrucci at the Qatar test, and used by Petrucci and Pramac Ducati’s Jack Miller during practice at the Qatar MotoGP round.

After Dovizioso won a thrilling, close race by a margin of 0.023 seconds from Marc Márquez, the top five finishing with six tenths of a second, but the race was the first time Dovizioso had used the new aero parts.

That prompted four factories – Aprilia, Honda, KTM, and Suzuki – to lodge a protest with the FIM Stewards, claiming that the aerodynamic device attached to the swingarm (see the tweet from contributor Tom Morsellino below) is illegal.

After conferring with the Technical Director Danny Aldridge, the FIM Stewards rejected the protest by the four factories, on the grounds that the aerodynamic devices used did not contravene the regulations.

The four factories then immediately lodged a protest, which they had prepared previously. According to Manuel Pecino, writing in the Spanish daily Mundo Deportivo, the parties involved had signaled in advance that they would be protesting Ducati’s use of the devices, if they were used in the race.

The appeal will now go forward to the MotoGP Court of Appeals, which will meet in Geneva, where they will consider the case. A judgment is expected to take a couple of weeks, and may not be ready before the next round of MotoGP at Termas de Rio Hondo in Argentina.

The results of the Qatar round of MotoGP will stand unless they are overturned by the Court of Appeal, although if they are overturned, and Ducati’s aero devices ruled illegal, Ducati are certain to appeal to the Court of Arbitration for Sport (CAS).

If the Court of Appeal upholds the ruling of the FIM Stewards, then that will settle the matter once and for all. No right of further appeal exists in that case.

The Letter of the Law

Speaking on Sunday night, Ducati Corse Sporting Director Paolo Ciabatti explained why Ducati believed the aero devices are legal. “It should be clear to everyone, because all manufacturers received a document from Danny [Aldridge] on the 2nd of March, which was guidelines for aerodynamics in general, mainly due to the bodywork,” he said.

“But it had a specific article related to that, saying that you can use [such parts] under certain limits: it has to be attached to the swing arm, it has to move with the swing arm, it has to be used for cooling, protecting from water, protecting the rear wheel from debris. We use it for cooling,” Ciabatti said.

This directly contradicted Danilo Petrucci, who told us on Friday, “We saw on television that it was for cooling down the rear tire but it is not like this. But I can’t tell you what it is for, because Gigi will get angry.”

Ciabatti said that Ducati had not wanted anyone to know that the purpose of the aero device was cooling, for the same reason they don’t tell anyone about what any of the rest of the bike does.

“We didn’t like to say this, because we don’t like to tell people what we are doing,” Ducati’s Sporting Director said. “But that’s the main purpose. Its purpose is not to create an aerodynamic force to the ground, which is what they say. And ours is not for that.”

Why So Late?

What Ciabatti objected to was the fact that the other factories had had eight days to either object, or to ask for clarification from Technical Director Danny Aldridge, but had waited until the race to do so.

“So everybody has had this for eight days, since Saturday last week. I think in principle, at least, my idea is that if you receive something from the Technical Director of the championship, and you don’t agree or you have doubts, you write back, saying ‘this is not good, this is not clear, we don’t agree, we think it’s not specifying enough because people might be cheating, and so on’. Nobody did that. And I hope everybody read it. So what can I say more?”

There were avenues which the other factories could have explored, Ciabatti pointed out. “I think everybody read [the directive]. But when you read it, why don’t you do the normal thing? We have the MSMA on one side, we have Danny, who is always available to answer. Just having eight days and then waiting to answer, is questionable.”

Ciabatti pointed out that that Dovizioso’s winning margin was still very tight, and with Danilo Petrucci finishing sixth, the difference these aero devices were making was very small. “Dovi won by 23 thousandths of a second,” he said. “When you are competing at this level, and you are competing against Honda, and against Márquez, who as we know is an exceptional rider, every fraction of second, every fraction of a hundredth of a second counts.”

“So, if we have something that is legal, and can give – obviously, for riders who are wearing more the rear tires like Danilo and Jack, it’s probably more useful in general – but if you think it is a fraction of a fraction of a millisecond advantage to Andrea on saving the tire for the last part of the race, why not, if it’s legal?”

But is it legal?

The question, of course, is whether it is legal or not. I spoke to Danny Aldridge on Friday, and he told me that the parts did not contravene the regulations. Reading the MotoGP regulations published on the FIM website (PDF), the rules on aerodynamics do not cover devices attached to the swingarm, or to the bottom of the front wheel, where the carbon covers are located.

Here is what the relevant part of the rules say:

The MotoGP Aero Body is defined as the portion of the motorcycle bodywork that is directly impacted by the airflow while the motorcycle is moving forward, and is not in the wake (i.e. aerodynamic “shadow”) of the rider’s body or any other motorcycle body parts. Therefore the Aero Body consists of the two separate components Front Fairing and Front Fender (Mudguard), as per the diagrams the Appendix, General:Fig.5, Fig.6.

To make the rules clear, the rule book also has a diagram:

If you compare this with Tom Morsellino’s photo included above, you can clearly see that Ducati have looked at the diagram and seen where the loophole was. They applied the covers to the bottom of the front wheel, and attached a spoiler to the bottom of the swingarm.

For the latter part, they may have been inspired by Yamaha’s rain deflector which made its debut last year (shown below, again in a photo by Tom Morsellino).

As these parts are not attached to what the rules call the Aero Body (the fairing and front fender), Ducati are free to attach and remove them as they see fit. This is why they do not fall under the ban on detachable aerodynamic parts, as set out in the rules.

Publish the Guidelines

Although the parts are legal under the FIM regulations as published, there is one key piece of information missing. The additional guidelines sent to the factories on March 2nd, and before that in February, are not available on the FIM website.

But, Paolo Ciabatti told us that it included a section explicitly allowing attachments to the swingarm, as long as such an attachment did not create downforce, but was used for either cooling or for deflecting water or debris.

The other manufacturers are claiming that this is where Ducati is breaking the rules. They do not believe that the rear spoiler – which is the part they are protesting against – is being used for cooling.

According to Aprilia CEO Massimo Rivola, speaking to Italian website, the CFD (computational fluid dynamics) simulations they had run showed that the rear spoiler was generating downforce on the rear wheel, something which is explicitly banned, according to the guidelines issued by Danny Aldridge. They showed Aldridge the simulation data, which showed the airflow over the rear spoiler.

But even then, Rivola doesn’t believe that it should be up to Aprilia or rival manufacturers to prove that the Ducati spoilers are not legal, but up to Ducati to prove with data that their parts are not violating the rules. “There are three wings on the inside of the spoiler, the classic tri-plane configuration. Why did they need three wings?” Rivola asked rhetorically.

Is Cooling Necessary?

Rivola was skeptical of Ducati’s claims that the spoiler is for cooling the tire. Sure, he told, it made sense if the device was only fitted to the bikes of Danilo Petrucci and Jack Miller, both of whom are known to be very heavy on tire consumption, not least because Petrucci is one of the heaviest riders on the grid.

But temperatures at Qatar were very low this year, and Andrea Dovizioso is 11 kg lighter than his teammate. Why would Ducati fit the spoilers to Dovizioso’s bike? What’s more, Dovizioso elected to use the medium rear tire, which theoretically should have less risk of overheating.

On the other hand, Ducati and Gigi Dall’Igna have made no secret of their focus on tire management as a way of using the excessive horsepower which the Desmosedici engine produces, without chewing up the rear tire halfway through the race.


That the rear spoiler has some form of aerodynamic effect is obvious, if only for the fact that it is only ever used in conjunction with the front wheel covers. However, whether the rear spoiler creates downforce or not is hard to see without seeing a simulation, or the bike in a wind tunnel.

Ex-Moto2 crew chief Peter Bom believes the parts work together to reduce turbulence and smooth the airflow. The front wheel covers smooth the air going onto the bottom half of the fairing.

The big question is what happens to that smooth (or laminar) airflow when it hits the rear spoiler. It is possible that the flow is more efficient in cooling the rear tire. It is also possible that it is generating more downforce on the rear wheel through the swingarm.

Or, as reader and engineer Andrew Gregory suggested to me by email, it could be acting as a venturi, to prevent the laminar flow on the underside of the fairing from slamming into the wall of turbulent air caused by the rotation of the rear wheel, thereby reducing drag.

Would that be a violation of the rules? Without being able to see the guidelines issued to the factories, it is impossible to say. If the guidelines specify that only devices creating downforce are banned, and the Ducati spoiler would be legal if it cooled the tire or reduced turbulence. If the guidelines say that devices may not create an aerodynamic effect, then Ducati’s spoiler would contravene the rules.

Money Pit

The real reason for the complaints is to try to rein in Ducati’s creativity with the aerodynamic regulations, something which Gigi Dall’Igna complained about at the Ducati launch. Aerodynamics is an area, like electronics, where factories can find incremental gains by throwing more resources at a project. That can quickly allow costs to spiral out of control.

The protest of the four factories was not aimed at Andrea Dovizioso, KTM’s Pit Beirer told German-language website Speedweek. “Hopefully Dovi won’t have this victory taken away from him,” Beirer said.

“He deserved this win. And so did Ducati, with the technical achievements. But we want clarity for the future, otherwise we will have wings sprouting everywhere. We want to make sure that these kinds of aerodynamic excesses are limited in the future.”

Ducati opened a Pandora’s box when they reintroduced wings after the adoption of the spec software, as an ingenious solution to countering wheelies using airflow instead of ECU software algorithms. Once the engineers were given that avenue to explore, they have found all sorts of fresh innovations and advantages.

The current MotoGP regulations were not written with aerodynamics in mind. As usual, the engineers have spotted a loophole, and driven a coach and horses – or rather, a fleet of race trucks – through it.

Photos: Ducati Corse