Danny Aldridge Explains Why Ducati's Aero Fairing Is Legal

The Brno round of MotoGP turned out to be a veritable bonanza of aerodynamic developments. Honda turned up with their previously homologated fairing, and Yamaha debuted a new fairing with a modified upper half at the test on Monday.

But it was Ducati who stole the show, with a radical new design featuring a large side pod that looked remarkably like a set of wings with a cover connecting them.

That fairing triggered howls of outrage from fans. How, they asked, was this legal? The fairing appeared to have two ducts that came out at the top at right angles, then return to the fairing at right angles.

That turned out not to be the full shape of the fairing, when Danilo Petrucci sported one where the bottom half of the side duct extended lower. It seemed to be a blatant breach of the rules.

The problem, MotoGP Technical Director Danny Aldridge explained, lay in part with framing of the rules.

When Dorna demanded a ban of the original winglets, they sat with the manufacturers to draw up a set of regulations that would limit aerodynamics and eliminate the risks, yet at the same time would allow some amount of development.

That proved impossible to do with the manufacturers so split among themselves, and so Dorna had to try to come up with a set themselves.

Factory rules

“To go back to the beginning, we requested to the manufacturers, ‘you give us some rules’. And they couldn’t,” Aldridge told us when we spoke to him about it at Brno. “Maybe the rules are too open at the moment,” he said, acknowledging the difficulties the ban on winglets has created.

Aldridge contrasted Yamaha’s aerodynamic package with the fairing Ducati debuted at Brno. “If you take the Yamaha design, it has a bulge on each side like this,” Aldridge said, making a smooth curved shape with his hands.

“Then if you take the Ducati design, it also has the bulge on each side but like this,” this time, making a much more squared off shape emulating the Ducati fairing. “If we say the Yamaha is correct, at which point does it go from correct to not correct?”

“This is the problem,” Aldridge continued. “You would need to start defining acceptable curvature and we don’t have that in the rule book now.”

“I will speak to the manufacturers about the present rules, if they feel they are not working or they are not happy. They have not come to me about it, but that would be my general opinion if they did; we would start to look at defining curvature and angles.”

Meeting of Minds

Yet there is already a dividing line between what is legal and what is not. At the moment, that dividing line is drawn up by Danny Aldridge based on the wording of the regulations. Aldridge does not do this alone, however.

“With all of these aero packages, the rule book states the final say is mine, but I understand that it’s such an important decision, so I also speak to other people such as [Race Director] Mike Webb and [MotoGP Director of Technology] Corrado Cecchinelli.”

“We sit down as a kind of mini-committee. I get their opinion and input until we get to a point where we all agree it’s within the rules. That’s when I allow it.”

The defining principle behind such calls is still safety. “The most important factor is safety,” Aldridge told us. “No sharp edges or something that could be dangerous to themselves, other riders or track marshals. And it must still be within the rules as far as the use of aerodynamic devices.”

“You obviously can’t take parts or material off so that it turns into a wing.” He was aware of Dani Pedrosa’s comments on the new fairing, but had not received a formal complaint.

“If we received a concern from the riders through the Safety Commission, or Race Direction, we would definitely look at it. One option might be to limit the opening of any ducts. Most riders don’t seem too concerned.”

Aldridge does not take the responsibility for ruling on the legality or otherwise of aerodynamic packages lightly. “It has given me sleepless nights for sure,” he admitted.

“Because the rules have both helped and hindered us. I’m trying to be fair to everyone and every decision sets a precedent. You’re always thinking, ‘how might this evolve?’ So it really helps talking everything through with Mike and Corrado. Three heads are better than one in some respects.”

Iterative Design

That process of consultation was one of the reasons the new Ducati fairing took such a long time to actually be used on track. The first version of the fairing was a long way from being legal.

“The design and homologation process has been going on for a few months. The first design they submitted, we said ‘no, you need to change this’. So it’s not a case they got everything they wanted,” Aldridge said.

It took an iterative process for Ducati to come up with a fairing that the Technical Director was willing to accept as legal, with Ducati returning with a new design four or five times before Aldridge was willing to give his blessing.

The process involved Ducati submitting a design, and Aldridge rejecting it and stating the reasons why it wasn’t legal. That is just the way that the rules work, Aldridge says. Once the rules have been drawn up, engineers start looking for the loopholes left by the letter of the law.

“Their job is to get to the limit and my job is to keep them within the limit,” Aldridge says. “So it’s finding a compromise. So what happens with the first design – and this has happened with other manufacturers as well obviously – is they say ‘is this allowed?’ And I say, ‘no, what you need to do is adjust this, this and this’ and so they come back with a version two, version three, version four.”

The Final Word

That the legality of a particular design is a matter of interpretation is a fact of life, Aldridge says. “The rules say it is down to the Technical Director’s interpretation and of course everyone has a different interpretation.”

“Some people say ‘it’s a wing, it shouldn’t be allowed’, others say they like it and understand why it was allowed. 20 people will give 20 different views.”

Adding more and more detail to the rule book would not prevent the arguments, though. “In F1 the aerodynamic rules are very strict, but they still have arguments every week about the developments,” Aldridge pointed out.

Perhaps the main reason fans objected to the Ducati aerodynamic fairing shown at Brno is because the first version the public saw was the version with just the upper duct, which features a sizable loop, rather than the full version which extends much lower down the fairing and seems slightly more reasonable.

That image of the short fairing sporting what appeared to be a set of wings was a shock to the system. Is Ducati’s fairing the absolute limit of what is allowed under the rules? “Definitely,” Aldridge emphatically replies.

“Honestly, we’ve been going to meetings with them for the last four or five races so there is not much more [that would be allowed]. A lot of people don’t like it, and I understand, but I think if you see the full version it is not as bad as if you only see the half version.”

He also explained why the two different versions of the fairing count as just a single update. “They have two versions [of the fairing],” Aldridge told us.

“They have the horizontal piece in the middle and, within the rules, you are allowed to remove material. So what they did was make it as one solid piece, it’s not hollow, and then they can cut off [the bottom part], smooth off the cut and paint it. Very clever.”

Hacking the Rules

There is a difference between the Honda, Yamaha, and Ducati fairings, however. Ducati’s new fairing is an update, and can only be used with either the upper, or both the upper and lower ducts fitted.

Honda and Yamaha homologated their fairings including side ducts at the beginning of the year, but the side ducts were detachable, allowing them to either fit them or remove them at particular tracks, depending on need.

“As the rules are written, they need to be an integrated part of the fairing,” Aldridge explained. “The Yamaha and Honda are bolted or riveted on, but the top part on the Ducati is molded into the fairing.”

Yamaha’s removable duct meant that it was able to introduce its update in Austria, after testing it at Brno. That fairing update featured a more wedge-like upper nose section, a little like the KTM, and including the side ducts used previously.

That the Yamaha upper fairing should resemble that of KTM is unsurprising. Factories are forever copying each other’s designs, or if not exactly copying them, then taking what they see and trying to refine it. As a result, the designs tend to converge in the end.

“There will be a lot of evolution,” Aldridge said. “As always in motorcycle racing, development goes off in different directions at first and then they all move closer together again.”

“The nose of the Ducati for example is the extreme of the KTM and the lower fairing is the extreme of the Suzuki. So they’ve gone to the limits. So this year we’ll probably see some way out stuff and then you might find next year all of the bikes start to merge towards a similar design.”